A simple circuit for an ignition timing corrector. Digital ignition timing regulator Microprocessor ignition control system
This article is devoted to further improvement of the octane corrector design, popular among car enthusiasts. The proposed additional device significantly increases the efficiency of its use.
V. Sidorchuk's electronic octane corrector, modified by E. Adigamov, is certainly simple, reliable in operation and has excellent compatibility with various ignition systems. Unfortunately, like other similar devices, the delay time of the ignition pulses depends only on the position of the ignition timing adjustment knob. This means that the set angle is optimal, strictly speaking, only for one value of the crankshaft speed (or the vehicle speed in a particular gear).
It is known that a car engine is equipped with centrifugal and vacuum automatic machines that correct the SOP depending on the crankshaft speed and engine load, as well as a mechanical adjustment octane corrector. The actual SOP at each moment is determined by the total effect of all these devices, and when using an electronic octane corrector, another significant term is added to the result obtained.
UOS provided by an electronic octane corrector, oz.ok=6Nt, where N is the engine crankshaft speed, min -1; t is the ignition timing delay introduced by the electronic octane corrector, s. Let's assume that the initial setting of the mechanical octane corrector corresponds to +15 degrees. and at N = 1500 min -1 the optimal ignition timing delay set by the electronic octane corrector is 1 ms, which corresponds to 9 degrees. crankshaft rotation angle.
At N = 750 min -1 the delay time will correspond to 4.5 degrees, and at 3000 min -1 - 18 degrees. crankshaft rotation angle. At 750 min -1 the resulting SOP is +10.5 degrees, at 1500 min -1 - +6 degrees, and at 3000 min -1 - minus 3 degrees. Moreover, at the moment the ignition delay switch-off unit is activated (N = 3000 min -1), the SOP will suddenly change immediately by 18 degrees.
This example is illustrated in Fig. 1 is a graph of the dependence of OZ () on the engine crankshaft speed. Dashed line 1 shows the required dependence, and solid broken line 2 shows the actually obtained one. Obviously, this octane corrector is capable of optimizing engine operation in terms of ignition timing only when the car is moving for a long time at a constant speed.
At the same time, it is possible, through simple modification, to eliminate this drawback and turn the octane corrector into a device that allows you to maintain the required SOP within a wide range of crankshaft rotation speed. In Fig. Figure 2 shows a schematic diagram of the unit that needs to be supplemented with an octane corrector.
The node works as follows. Low-level pulses taken from the output of the inverter DD1.1 are fed through the differentiating circuit C1R1VD1 to the input of the timer DA1, connected according to the one-shot circuit. The output rectangular pulses of the single-vibrator have constant duration and amplitude, and the frequency is proportional to the engine crankshaft speed.
From the voltage divider R3, these pulses are sent to the integrating circuit R4C4, which converts them into a constant voltage, which is directly proportional to the crankshaft speed. This voltage charges the timing capacitor C2 of the octane corrector.
Thus, with an increase in the crankshaft rotation speed, the charging time of the timing capacitor to the switching voltage of the logical element DD1.4 is proportionally reduced and, accordingly, the delay time introduced by the electronic octane corrector is reduced. The required dependence of the change in charging voltage on frequency is ensured by setting the initial voltage on capacitor C4, which is removed from the slider by resistor R3, as well as by adjusting the duration of the monovibrator output pulses with resistor R2.
In addition, in the octane corrector, the resistance of resistor R4 must be increased from 6.8 to 22 kOhm, and the capacitance of capacitor C2 must be reduced from 0.05 to 0.033 μF. The left terminal of resistor R6 (X1) in the diagram is disconnected from the positive wire and connected to the common point of capacitor C4 and resistor R4 of the added node. The supply voltage to the octane corrector is supplied from the parametric stabilizer R5VD2 of the additional unit.
The octane corrector with the specified modifications provides adjustment of the ignition timing delay, equivalent to a change in SOP within the range of 0...-10 degrees. relative to the value set by the mechanical octane corrector. The operating characteristics of the device under the same initial conditions as in the example above are shown in Fig. 1 curve 3.
At the maximum ignition timing delay time, the error in maintaining the SOP in the crankshaft speed range of 1200...3000 min -1 is practically absent, at 900 min -1 it does not exceed 0.5 degrees, and in idle mode - no more than 1.5 ...2 deg. The delay does not depend on changes in the voltage of the vehicle’s on-board network within 9...15 V.
The modified octane corrector retains the ability to provide sparking when the supply voltage is reduced to 6 V. If it is necessary to expand the control range of the SPD, it is recommended to increase the resistance of the variable resistor R6.
The proposed device differs from similar ones described in circuit simplicity, reliable operation, and the ability to interface with almost any ignition system.
The additional unit uses permanent resistors MLT, tuning resistors R2, R3 - SP5-2, capacitors C1-C3 - KM-5, KM-6, C4 - K52-1B. Zener diode VD2 must be selected with a stabilization voltage of 7.5...7.7 V.
The assembly parts are placed on a printed circuit board made of foil fiberglass laminate with a thickness of 1...1.5 mm. The board drawing is shown in Fig. 3.
The node board is attached to the octane corrector board. It is best to mount the entire device assembly in a separate durable casing, secured near the ignition unit. Care must be taken to protect the octane corrector from moisture and dust. It can be made in the form of an easily removable block installed in the car interior, for example, on the side wall below, to the left of the driver’s seat. In this case, with the octane corrector removed, the electrical ignition circuit will be open, which will at least make it very difficult for an unauthorized person to start the engine. Thus, the octane corrector will additionally serve as an anti-theft device. For the same purpose, it is advisable to use an adjustable variable resistor SP3-30 (R6) with a switch that opens the electrical circuit of this resistor.
To set up the device, you will need a power source with a voltage of 12...15 V, any low-frequency oscilloscope, a voltmeter and a pulse generator, which can be done as indicated in. First, the input circuit of the timer DA1 is temporarily turned off, and the resistor R3 slider is set to the lower (according to the diagram) position.
Pulses with a frequency of 40 Hz are supplied to the input of the octane corrector and, by connecting the oscilloscope to its output, resistor R3 gradually increases the voltage on capacitor C4 until output pulses appear. Then the input circuit of the timer is restored, the oscilloscope is connected to its pin 3 and the duration of the monostable output pulses is set with resistor R2 to 7.5...8 ms.
The oscilloscope is connected again, switched to external synchronization mode with a standby sweep triggered by input pulses (it is best to use a simple two-channel switch), the output pulse delay time is set to 1 ms with resistor R6. Increase the generator frequency to 80 Hz and use resistor R2 to set the delay time to 0.5 ms.
After checking the delay duration of the pulses at a frequency of 40 Hz, the adjustment is repeated, if necessary, until the duration at a frequency of 80 Hz is exactly half that at a frequency of 40 Hz. It should be borne in mind that in order to ensure stable operation of the one-shot device up to the operating frequency of the ignition delay switch-off unit (100 Hz), the duration of its output pulses should not exceed 9.5 ms. In fact, in an adjusted device it does not exceed 8 ms.
Then the generator frequency is reduced to 20 Hz and the input pulse delay obtained at this frequency is measured. If it is at least 1.6...1.7 ms, then the adjustment is completed, the adjusting screws of the trimming resistors are fixed with paint, and the board, on the side of the printed conductors, is covered with nitro varnish. Otherwise, resistor R3 slightly reduces the initial voltage on capacitor C4, increasing the delay time to the specified value, after which it is checked and, if necessary, adjusted again at a frequency of 40 and 80 Hz.
You should not strive for strict linearity of the frequency dependence of the delay time in the area below 40...30 Hz, since this requires a significant reduction in the initial voltage on capacitor C4, which can lead to loss of ignition pulses at the lowest crankshaft speeds or unstable operation of the ignition system at starting the engine.
A small residual error, expressed in a slight decrease in the ignition delay time at the initial stage (see curve 3 in Fig. 1), has a positive rather than a negative effect, since (car enthusiasts know this well) at low speeds the engine operates more stable at a slightly earlier ignition.
You can adjust the device with quite acceptable accuracy without an oscilloscope. They do it like this. First, check the functionality of the additional node. To do this, set the resistor motors R2 and R3 to the middle position, connect a voltmeter to capacitor C4, turn on the power to the device and apply pulses with a frequency of 20...80 Hz to the input of the octane corrector. By rotating the slider of resistor R2, make sure that the voltmeter readings change.
Then the slider of resistor R2 is returned to the middle position, and resistor R6 of the octane corrector is moved to the position of maximum resistance. The pulse generator is turned off, and resistor R3 sets the voltage on capacitor C4 to 3.7 V. Pulses with a frequency of 80 Hz are applied to the input of the octane corrector and resistor R2 sets the voltage on this capacitor to 5.7 V.
Finally, voltmeter readings are taken at three frequency values - 0, 20 and 40 Hz. They should be 3.7, 4.2 and 4.7 V, respectively. If necessary, repeat the adjustment.
Connecting the modified octane corrector to the on-board system of cars of various brands has no special features compared to what is described in.
After installing the octane corrector on the car, starting and warming up the engine, move the resistor R6 slider to the middle position and use the mechanical octane corrector to set the optimal OZ, as indicated in the car’s operating instructions, i.e., achieve slight, short-term detonation of the engine when pressed sharply on the accelerator pedal while the car is moving in direct gear at a speed of 30...40 km/h. This completes all adjustments.
Literature
Generally speaking, changing the set ignition timing should be considered as a temporary and forced measure, in particular, if it is necessary to use gasoline with an octane number that does not correspond to the passport characteristics of the car engine. Nowadays, when the quality of the fuel that we fill into the tank of our car has become, to put it mildly, unpredictable, a device such as an electronic octane corrector is simply necessary.
As quite rightly noted in the article by K. Kupriyanov, when introducing the octane corrector described in. There is a constant time delay of the ignition timing, proportional in angular terms to the increase in the engine crankshaft rotation speed, followed by a sudden increase in the OC angle. Although in practice this phenomenon is almost imperceptible, the internal reserves of the original device make it possible to partially eliminate the mentioned delay. To do this, it is enough to insert transistor VT3 and resistors R8 into the device. R9 and capacitor C6 (see diagram in Fig. 1).
(click to enlarge)
The operating algorithm of the octane corrector is qualitatively illustrated by the graphs shown in Fig. 2. The moments of opening of the breaker contacts correspond to positive voltage drops - from low to high levels - at the input of the octane corrector (diagram 1). At these moments, capacitor C1 is quickly discharged almost to zero through the opening transistor VT1 (diagram 3). The capacitor charges relatively slowly through resistor R3.
As soon as the voltage on the charging capacitor C1 reaches the switching threshold of the logical element DD1.2. it goes from a single state to a zero state (diagram 4), and DD1.3 - to a single state. Transistor VT2, which opens at this moment, quickly discharges capacitor C2 (diagram 5) to a level practically determined by the voltage at the base of transistor VT3. Since the switching delay of element DD1.2 does not depend on the rotational speed, the average voltage at its output increases with increasing frequency. Capacitor C6 averages this voltage.
Subsequent charging of capacitor C2 through resistor R6 begins precisely from the specified level at the moment the transistor VT2 closes. The lower the initial level, the longer the capacitor will charge until the element DD1.4 switches, which means the longer the spark formation delay (diagram 6).
The resulting characteristic of the OZ angle is shown in Fig. 3, similar to Fig. 1 in the article by K. Kupriyanov, in the form of curve 4. Under the same initial conditions (tset = 1 ms at N = 1500 min-1), the control error in the engine crankshaft speed range most often used when driving is from 1200 to 3000 min-1 1 does not exceed 3 degrees.
It should be noted that the operation of this version of the octane corrector significantly depends on the duty cycle of the input pulses. Therefore, to set it up, it is recommended to assemble a pulse shaper according to the diagram in Fig. 4. As is known, pulses from the Hall sensor of the VAZ-2108 car and its modifications have a duty cycle of 3, and the closed state angle of the contacts φзс of the contact breaker of VAZ cars is equal to 55 degrees, i.e., the duty cycle of pulses from the “six” breaker Q = 90/55= 1.63.
In order to be able to use the same pulse shaper to set up octane correctors for different car models with only a small adjustment of the duty cycle, for a contact ignition system the duty cycle is recalculated taking into account inversion: Qinv = 90/(90 - φзс). or for VAZ-2106 Qinv = 90/(90 - 55) = 2.57. By selecting the number of diodes of the shaper and the sinusoidal voltage of the signal generator, the required duty cycle of the pulses at the input of the octane corrector is obtained. In my practical version, to obtain a duty cycle of 3, four diodes were needed with a generator signal amplitude of 5.7 V.
In addition to those indicated, diodes of the D220 series are suitable for the driver. D223, KD521, KD522 and transistor KT315 with any letter index. You can use a pulse shaper of a given duty cycle according to another scheme.
The corrector for the VAZ-2108 car (jumper X2.3 is inserted in Fig. 1) is adjusted as follows. Instead of the divider R8R9, any variable resistor of group A with a resistance of 22 kOhm is temporarily connected (with the slider to the base of the transistor VT3). First, the resistor slider is set to the extreme position in which the base of the transistor is “grounded.” A shaper is connected to the input of the corrector, and an oscilloscope is connected to the output.
Turn on the power to the corrector and set the generator frequency to 120 Hz with the duty cycle of the output pulses of the shaper equal to 3. Select resistor R3, ensuring that the delay is turned off at this frequency. Then the generator frequency is reduced to 50 Hz and, by moving the resistor R6 slider alternately to both extreme positions, the maximum ignition timing delay time introduced by the octane corrector is determined (in our case, 1 ms). Increase the generator frequency to 100 Hz and find the position of the temporary variable resistor engine in which the maximum ignition timing delay, set by resistor R6, is found. equal to half the maximum - 0.5 ms.
Now it is advisable to take a graph of the dependence of the ignition timing delay time on the generator frequency at the found position of the temporary variable resistor engine. Recalculate the engine shaft rotation speed in min-1: N = 30f. where f is the generator frequency. Hz Angle of protection φoz = 6N·t, where t is the delay time, ms. The resulting angle φrez oz = 15 - φoz (see table) is plotted on the graph in Fig. 3.
The shape of the resulting graph should not differ much from curve 4, although the numerical values may be different depending on the maximum delay time. If necessary, repeat the adjustment operation.
Upon completion of the installation, turn off the temporary variable resistor and, having measured the resistance of its arms, solder in permanent resistors with values closest to the measured ones. It should be noted that the control characteristic can be significantly changed by varying the values of resistor R3 (delay cut-off frequency), divider R8R9 and capacitor C6. The initial conditions of the described adjustment were chosen for comparison with the option chosen by K. Kupriyanov: N = 1500 min-1, t = 1 ms, φmok = +15 deg. (φmok is the angle set by the mechanical octane corrector).
For use on a VAZ-2106 car, the octane corrector is set up in a similar way (with jumper X2.3), but the pulses from the driver must have a duty cycle of 2.57. Before installing the corrector on the car, jumper X2.3 is changed to X2.2.
To modify the octane corrector, its board is removed from the switch 3620.3734 and the transistor VT3 and capacitor C6 are soldered in such a way that the board can be installed in its old place. Selected resistors R8 and R9 are soldered onto the board. Transistor V13 and capacitor C6 should be fixed with Moment glue or the like.
Instead of KT3102B, any transistor of this series will do. Capacitor C6 - K53-4 or any tantalum or oxide semiconductor, suitable in size and rating.
Literature
V. Petik, V. Chemeris, Energodar, Zaporozhye region.
Currently, many car enthusiasts are showing increased interest in devices for electronic control of the ignition timing (IAC) or octane correctors (OC), which allow fuel savings of 5-10% and adapt the engine to fuel of different qualities, increase maximum power and reduce exhaust toxicity . Existing circuit solutions have some disadvantages:
– the SPD delay is carried out for a fixed period of time, which at different engine shaft speeds corresponds to different SPD;
– when constructing delay circuits for a fixed SPD, their complexity increases significantly.
Taking into account the above, the authors have developed a simple and effective OK, in which the SOP remains constant at any engine shaft speed. The OK block diagram is shown in Fig. 1. The principle of its operation is based on the proportionality of the SPD delay to the period of shaft rotation. Pulse sequence, in
which, within certain limits, it is necessary to delay the positive edge, is generated by a chopper and is supplied to the input of the circuit. In this case, the duration of the pause is used as a reference value, which is fixed by the reference frequency generator G1 and the reverse counter CT operating in stack mode, i.e. when the level at input ±1 is low, it works to increase the count (accumulation of information), and if there is a high level at the same input, it works to decrease it (reading accumulated information). In the first case, generator G1 operates, and in the second, generator G2 operates, and G1 is blocked,
the frequency of which can be changed. If the frequencies of G1 and G2 are equal, the SPD delay will be 90 degrees, therefore, to ensure a delay of up to 30 degrees. it is necessary that the frequency of G2 be 3 or more times higher than the frequency of G1. At the end of the counting, when the counter has given all the accumulated information, a signal is generated at its output P, which sets the output of the RS trigger to a high level, blocks the operation of the counter and is a delayed output signal. The circuit returns to its original state when a low level arrives at its input, which resets the RS flip-flop, and the cycle repeats.
The OK circuit diagram and diagrams of its operation are shown in Fig. 2 and Fig. 3, respectively. A low-frequency filter R3-C3 is installed at the input of the circuit, which, together with cells DD1.1, DD1.4, containing Schmitt triggers at the input, eliminates the influence of breaker contact bounce on the operation of the circuit. Generator G1 is assembled on DD1.3, DD1.2, R7, C2 and to prevent overflow of counters DD2, DD3 at low engine speeds it is set to a frequency of 1 kHz. Generator G2 is assembled on DD1.1, DD1.2, R4, R5, C1. With variable resistor R4 you can change its frequency from 3 to 90 kHz, which ensures adjustment of U03 from 30 to 1 degree. respectively. Counters DD2, DD3 are cascoded, which allows increasing their total capacity to 256 bits. The counters first accumulate information about the duration of the closed state of the breaker contacts, and after they open, they read it. When the accumulated information is fully read, a short-term negative pulse appears at pin 7 of the DD3 counter, which, through cell D04.3, switches the RS trigger assembled on cells DD4.2 and DD4.4, from the inverse output of which a blocking signal for the counter DD2 is generated and through DD4. 1, R6, VT - output delayed signal.
Details. The K561TL1 microcircuit can be replaced with a K561LA7, but after the low-pass filter it is necessary to install a Schmitt trigger assembled according to any known circuit. Any Zener diode VD for a voltage of 5-9 V. The KT972 transistor can be replaced with a pair of KT3102, KT815 (KT817). Capacitors C1 and C2 must be selected of the same type or with the same TKE, as far as possible
closer to zero. The same applies to resistors R5, R7. It is advisable to install a 0.1 µF ceramic capacitor parallel to each microcircuit along the power buses, and a tantalum electrolytic capacitor parallel to VD.
Setup. To configure the generators, you need to install the frequency meter probe on pin 4 of the DD1.2 microcircuit, then apply a low logic level to the circuit input and select resistor R7 so that the generator frequency is 1 kHz. Next, set the slider of resistor R4 to the lower position according to the diagram, apply a high logical level to the input and select resistor R5 current so that the frequency meter readings are equal to 90 kHz, which will correspond to a delay of U03 of 1 degree.
In the upper position of the R5 slider, the generator frequency should be about 3 kHz, which corresponds to a U03 delay of 30 degrees. If desired, this value can be changed up or down by changing the value of R4, which is set on the control panel. It is advisable to shield the wires. Literature
1. Kovalsky A., Fropol A. Octane-corrector attachment // Radio.-1989.-No. 6.-P.31.
2. Sidorchuk V. Electronic octane corrector // Radio. -1991.-No.11.-C.25.
3. Bespaloe V. OZ angle corrector // Radio.- 1988.-No. 5.-p.17.
4. Arkhipov Yu. Digital ignition timing regulator // Radio Yearbook.-1991.-P.129.
5. Romanchuk A. Octane corrector on CMOS microcircuits // Radio Yearbook.-1994. -I5.-S.25.
When operating a car, sometimes, depending on the quality of the fuel being filled, it becomes necessary to adjust the ignition timing.
Octane corrector device:
- frame;
- octane corrector;
- screw
How to adjust the ignition timing?
The ignition timing is adjusted by octane corrector 2 of the ignition distributor, which allows you to reduce or increase the ignition timing. The signs “+” (advance) and “–” (lag) marked on the octane corrector scale indicate the direction of its rotation.
Adjust the ignition timing on a warm engine. Before making adjustments, mark the position of the middle mark of the octane corrector on the cylinder block.
Adjusting the angle for detonation
When driving on a flat road in direct gear at a speed of 50 km/h, sharply press the accelerator pedal. If a slight and short-term detonation occurs, then the ignition timing is set correctly. In case of strong detonation (early ignition), loosen nut 3 and turn housing 1 0.5–1 division clockwise (to “–”).
If there is no detonation (late ignition), turn housing 1 0.5–1 division counterclockwise (to “+”).
Fixing the adjusted position
After adjustment, tighten nut 3 and check again for correct ignition timing when driving.
Yu. Arkhipov
It is known that an optimally specified and reproducible dependence of the ignition timing angle (IAF) in the entire range of conditions and operating modes of an internal combustion engine contributes not only to the most efficient combustion of the working mixture, obtaining maximum engine power and throttle response, increasing its efficiency and reducing toxicity, but also achieving uniformity of operation (smooth running) and, as a result, an increase in engine life. In modern automotive practice, the OC angle on a specific type of engine most often depends on the following five factors:
octane characteristics of gasoline;
engine crankshaft speed N;
vacuum in the rear throttle space of the carburetor, which characterizes the load on the engine;
coolant temperature;
humidity of the air entering the carburetor.
The sequence of their listing fully reflects the history of improving ignition systems, and in fact, the degree of influence of these factors on the quality level of engine building. The exception is the last two, which should be swapped. However, taking into account the influence of air humidity still remains a technically intractable problem and therefore is rarely implemented in practice. The reason is the lack of compact, cheap sensors with acceptable characteristics. And the attentive motorist notes that this is desirable every time, comparing the “soft” rhythmic operation of the engine in wet weather with the “ringing” uneven operation in dry weather.
The listed factors can be divided into rapidly changing ones, depending on the engine operating mode (rotation speed and load) and relatively long-term ones (all others). Therefore, the first of them must be taken into account automatically, which on domestic automobile engines is carried out separately by a centrifugal automatic machine and a vacuum corrector (if there is one). The latter, if they are not taken into account automatically, due to their inertia, could be adjusted manually, especially since it is necessary to correct (shift or modify) the entire curve “OZ angle - crankshaft rotation speed”, i.e. f(N) (in in the text this is the letter phi (N) approx. P.V. Krylov), which is a characteristic of a centrifugal machine.
The vast majority of motorists, remembering this automatic machine, usually ask two questions: what should be the most advantageous adjustment curve of “his” engine copy and to what extent does it correspond to what is actually reproduced. The answer to the first question is given in, on p. 39: “Each type of engine has its own optimal characteristics for changing the ignition timing depending on the rotation speed and load. When using the fuel recommended by the instructions, they practically do not change from one copy to another.” Further on p. 40: “...the characteristics of centrifugal governors of most modern engines at low crankshaft speeds are significantly lower than optimal, which naturally entails a loss of power in this mode (sometimes up to 5... 10%).”
In confirmation of this, on p. 42 shows three graphs of detonation dependencies and one of maximum power related to the VAZ engine, which are presented in Fig. 1 unchanged.
Rice. 1. Adjusting the ignition timing along the detonation limit (using the example of a VAZ engine)
As in the original source, in Fig. 1 also shows the “factory” characteristics of the ignition distributor of type 30.3706 at the initial (installation) angle of OP = 7°. As you can see, it is far from the closest graph 2 not only and not so much at N - 500... 1500 rpm, but in the range 2700... 4700, i.e. exactly in the region of the most common rotation speed, corresponding to the maximum torques. Theoretically, such a mismatch can be easily corrected to a large extent if the bracket of the second (hard) spring of the centrifugal machine is bent so that it comes into operation after N = 3300 rpm, thereby extending the operating interval of the first (weak) spring to the same limit and, In addition, replace the second spring with a stiffer one. However, even after this, in the area of 2700...3200 rpm, the deviation will be about 5°, and at low rotation speeds it remains the same.
In practice, although this is a simple, but very labor-intensive job, which requires at least a strobe light and a specially made sector with angular markings. But the main thing is that during the adjustment process, due to the instability of the centrifugal machine, random errors when opening the breaker contacts, and due to inaccurate setting of the rotation speed, errors can be up to ±5...7°. Within the same limits, the strobe mark flickers (at N more than 2500 rpm), characterizing the spread of reproducible angles of view. At the service station, at best, they will set a “factory” curve (or say that they did) with the same factory tolerance limits.
The described digital angle controller OZ (TsifRUOZ) is a synthesizer of the function φ(N) based on PROM and an auxiliary corrector. The regulator is intended for use instead of a centrifugal (mechanical) machine in conjunction with an automated electronic ignition unit (ABEZ) or any other electronic ignition system, provided that its control input is matched with the synthesizer output in phase, voltage amplitude and pulse power.
The error in the presentation of the initial characteristics of the OZ is determined by stepwise digitization of their values, and at N more than 615 rpm does not exceed ±0.3°. At a lower rotation speed, the angle of rotation is set equal to the initial one. The maximum number of characteristics recorded in memory and the accuracy of their approximation are limited only by the capacity of the EEPROM. The applied IC K556RT7 (or K556RT18) allows you to record two or four characteristics with deviations from the original ones, respectively, up to ±0.3° and ±0.5°, and for example, IC K556RT5 - only one and with the largest of these deviations. It is possible to “switch” the recorded dependencies manually according to the octane characteristics of the used brands of gasoline and smoothly shift each of them along the engine speed axis, and with the help of a corrector, in addition, adjust the slope and change the initial angle of the OZ.
The synthesizer is designed to work mainly with a contactless ignition signal sensor. Moreover, for the programs recorded in the memory, it is assumed that at each half-turn of the crankshaft (four-stroke four-cylinder engine) the sensor gives a signal/pause ratio of 135°/45°. If it is different, you will have to change the EPROM programming table. The choice of this ratio is due only to the higher accuracy of approximation of the original characteristics. The synthesizer can also be used with a chopper, for which the controller contains a control signal converter to signal/pause type 135°/45°. At the same time, it also performs the functions of the mentioned proofreader.
The schematic diagram of the regulator is shown in Fig. 2, and the time diagrams of operation are in Fig. 3.
The synthesizer includes a clock pulse generator (TI) of constant frequency, a pulse counter, the number of which characterizes the period of rotation of the crankshaft (T) (otherwise known as a period counter (PcT), a pulse counter for generating a control signal (otherwise known as a control counter (CCU), EPROM, a comparison device and a trigger for fixing the coincidence of codes, a pulse generator for resetting counters, an output stage for generating an ignition signal. In addition, the synthesizer has an indicator of its proper operation and a pulse power supply device IC PROM. The corrector (aka signal converter) consists of an RS trigger, a differential type integrator and a Schmitt trigger on operational amplifiers (op-amps), their bipolar power source.
The TI generator is assembled on two logic elements DD7.3 and DD7.4 (the first is switched on by a repeater, the second by an inverter) according to a circuit with high frequency thermal stability - 0.05...0.07% per °C. To improve it another 2-3 times, a temperature-compensating capacitor is used as C2. And since the real temperature range of the regulator’s operation does not exceed 60°, the maximum frequency shift of the TI generator causes a shift in the angle 03 of no more than 0.5°. Moreover, as the frequency increases, the angle decreases, which should be considered a favorable circumstance, since a regulator installed, for example, under the hood will respond to an increase in engine temperature in the desired direction. The duration of the TI is determined by the timing circuit R7C2 and is equal to 1.8...2.2 μs, and the frequency is determined by the circuit R5R6R8C2, which, depending on the details of recording the characteristics in memory, can be equal to 28 or 14 kHz (respectively R5 - 39 k and 75 k ). The exact frequency value is set by resistor R6, and its operational change in order to shift the characteristics along the axis is carried out by resistor R8.
The period duration counter is 10-bit, and the control counter is 8-bit. The first is made on ICs DD1 and DD2.1, and the second is made on ICs DD3. The output code of the period counter is the address code of the PROM (DD4).
The applied IC (2048X8 resolution) allows you to record, as noted, two or four characteristics of the OZ. Shown in Fig. Option 2 corresponds to two characteristics that can be switched using SA1 by applying the 21st significant bit of the log address to the input. "0" or "1". In the case of recording four characteristics, it is also necessary to switch the output of the 22nd 10th bit of the address, disconnecting it from the period counter.
The comparison device consists of eight “exclusive OR” elements - DD5 and DD6. The outputs of the EEPROM and the control unit are connected to their inputs in bit pairs, and the diode assembly VD3 - VD10 with load resistor R9 is connected to the outputs. A trigger for fixing a code match is connected to the output of the assembly, for which a DD2.2 counter is used. It controls the operation of the output stage, assembled on the DD7.2 element and the VT1 transistor. Diode VD12 and resistor R12 ensure reliable closing of the transistor at log. “0” at the output DD7.2, which corresponds to a voltage of 0.3...0.5 V. When operating the synthesizer together with ABEZ, they are not needed, but the emitter of the transistor should be connected to point Upit 2. The need for a trigger for fixing the coincidence of codes is due to the task of obtaining on the VT1 collector the same signal shape as on the VT5 ABEZ collector. Without it, the code matching signal would only exist during the TI, since the EPROM has pulse power.
With the beginning of a positive pulse in the signal of the contactless sensor (PD) F, i.e. the measuring interval, which corresponds to the 135° sector of rotation of the crankshaft (Fig. 3, a), using the differentiating circuit R1C1 and the Schmitt trigger on the DD7 element. 1, a positive pulse with a duration of 3...5 μs is generated to reset all counters, including DD2.2.
At the same time, the log level is set at the inputs of CN DD3 (pins 1 and 9). “1”, excluding the influence of TI on the CP inputs (pins 2 and 10). Using the inverted signal of the sensor F (Fig. 3, b), the log level is set at the CN DD1 and DD2.1 inputs. “0”, allowing pulse counting (Fig. 3d). By the way, both sensor signals, direct and inverted, are the voltages on the collectors of VT5 and VT4 ABEZ, respectively. The triggers of the counters used in the synthesizer are switched at the moments of decline of positive pulses at the CP inputs. The first TI, which occurs simultaneously with the zeroing pulse (Fig. 3, c), is not taken into account by the counter, since the input R is the predominant one.
At the end of the measuring interval, the logical levels at the CN inputs are reversed, the counter is stopped, and the counter begins counting clock pulses. When its output code becomes the same as the output code of the PROM, all outputs of the comparison circuit will be set to “0”, and resistor R9 will experience a positive pulse drop (Fig. 3d), which will transfer the low-order output bit of DD2.2 to “1” ( Fig. 3, f). After this, a log will be set at the output of element DD7.2. “0” (Fig. 3,g), since at both its inputs there is a log. “1”, transistor VT1 will close and a positive pulse will appear on the collector, which is an ignition signal (Fig. 3,h). When working with ABEZ, you need to connect capacitor C6 to the synthesizer output, disconnecting it from the collector VT5 (ABEZ). It is most convenient to connect it to a connector pin with two sockets: connect the VT5 ABEZ collector to one, and connect the VT1 synthesizer collector to the other.
Using diodes VD1, VD11, positive potentials are applied to the GTI, causing generation to fail (GTI stop).
This is necessary when the meter overflows, which is possible at low speeds, as well as when the comparison device is triggered. In the first case, if the GTI had not stopped, after the SchT counter overflowed, the PROM address code, and with it the output code, would begin to repeat. After the end of the measuring interval, the operation of the control unit would inevitably lead to false, i.e., not corresponding to the control law, operation of the comparison circuit and output stage. Moreover, the value of the angle OZ could be any, from the initial to the maximum, but should be exactly equal to the initial one. To eliminate this, a positive pulse that occurs when the counter is overflowed at pin 5 of DD2.1 forcibly sets the GTI level to a log level at pin 8 of DD7.3 (“output 1”). "1". In this case, the log level remains at pin 11 of DD2.2. “0” and the output stage is triggered by the decline of the positive pulse in the inverted DB signal, which means that the reproduced angle 03 is equal only to the initial fn, which is determined by the DB setting. This technique (stopping the GTI) is preferable to all others because with the beginning of each new measuring interval, the generation of clock pulses begins with the same phase. This advantage is also important in the second case, especially at rotational speeds of 2500...3200 rpm, for which two addresses that differ by one correspond to the maximum change in the OC angle.
The synthesizer uses pulsed power supply of the EEPROM, because with the existing high duty cycle of the TI (15...40) it is simpler in circuit design and design, more economical and more favorable in terms of the thermal regime of the IC. The device is a two-stage power amplifier using transistors VT2, VT3. Control signals are supplied to it from “output 2” of the GTI (pin 11 of DD7.4), which are antiphase to the TI. Since the switching delay of the counters (100...200 ns) is significantly longer than the output time of the PROM after switching on to the operating mode (30...60 ns), it actually works with address codes as well as with a constant supply voltage, which eliminates false operation of the device comparisons based on transient codes at the output of the EEPROM.
The synthesizer includes a failure indicator, which includes VT4, VT5, R17 - R20, C3 and the HL1 LED. Transistor VT4 and integrating circuit R18C3 make up the peak detector, and VT5 is the power amplifier. The controlled signals are positive pulses at the output of DD2.2. With a decrease in their duty cycle, which corresponds to an increase in the rotation speed and (or) angle of reference, the brightness of the LED increases.
To compile a programming table based on those shown in Fig. 1 graphs can be used in many ways. It turned out to be most rational to replace the characteristics of the OZ with sets of polynomials of low order, the easiest way is with quadratic parabolas of the form
Therefore, it should be the minimum of all VA characteristics recorded in memory at N=Nmin (in the synthesizer fn=6°). Examples and the procedure for recording the results of calculations using formulas (1) - (4) for a number of characteristic points of the dependence f(N), compiled from graphs 2 (for AI-93 gasoline) and 4, are given in table. 1. It also contains relevant data for the case of writing f(N) with a nine-bit PROM address.
In table 1:
The shift of the graph f(N) is shown in Fig. 4.
As you can see, when the GTI frequency changes, the appearance of the graph also changes, but the predominant trend is a shift. By the way, the modification turns out to be favorable: when the OZ characteristic shifts to the right (with an increase in frequency), the slope of its detonation in graph 2 becomes smaller, and when shifted to the left, it becomes larger. The upper part (graph 4) remains virtually unchanged.
When operating a synthesizer with a non-contact sensor, there is no practical need for other adjustments. Having 2-4 “switchable” dependences f(N) and the ability to change the GTI frequency by ±7...5%, it is possible, with the above accuracy, to cover the entire range of detonation characteristics corresponding to the brands of gasoline AI-98 (95), AI-93 , A-76 and their surrogates. The EEPROM selected when compiling the programming table and the initial OC angle set once during engine operation obviously will not need to be adjusted, because usually the databases do not contain wearing parts that affect the fnl. The maximum accuracy of the synthesizer (with a 10-bit EPROM address) can only be realized with a sensor that is controlled directly from the crankshaft (structurally, most often from the flywheel). The traditional drive of the sensor from the ignition distributor shaft introduces a random error in the OC angle of up to 0.5... 1°. In this case, it would be rational to limit ourselves to a 9-bit address, which will reduce the required amount of memory or double the number of recorded RAM characteristics.
The synthesizer can also be used with a conventional chopper, if it is supplemented with a converter of control signals to the required type (see Fig. 3, a). The schematic diagram and timing diagrams of the operation of such a device are presented in Fig. 5 and 6.
It works like this.
When the breaker contacts open (Fig. 6, a), the Q-output of the RS trigger, assembled on logic elements DD8.1 and DD8.2, is set to level “1” (Fig. 6, b). The corresponding voltage acts on the non-inverting input of the integrator DA1.1, and on the inverting input - “0” from the Q-output of this trigger. The integrator output voltage is
Therefore, following the switching of the RS trigger, the voltage at the input of the Schmitt trigger - the non-inverting input of the op-amp DA1.2 - will increase linearly (Fig. 6c). When it reaches the trigger switching threshold, a positive voltage drop will occur at the cathode of diode VD4, i.e., a log level. "1", which will switch the RS flip-flop to the opposite state. After this, Uout1 will begin to decrease linearly until the next opening of the breaker contacts or to the minimum possible voltage at the output of op-amp DA1.1, if the opening frequency corresponds to 400...500 rpm. At the beginning of the descending branch of the Uout1 graph, the Schmitt trigger will return to its original state. Thus, during switching, short positive pulses are formed at its output (Fig. 6d), the duration of which is determined by the ratio of the resistances of resistors R8, R9 and the value of t1. With the values indicated in the diagram, it is approximately 0.5 ms, and the width of the hysteresis loop of the Schmitt trigger is about 0.3 V. The trigger threshold is equal to the voltage on the zener diode VD3, and the thermal stability of the threshold is determined by the total TKN of this zener diode and diode VD4.
Obviously, the duration of the positive pulse at the Q-output of the RS trigger corresponds to the measuring interval in the contactless sensor signal, and the pause corresponds to the control interval. The relationship between them within the limits of device stability and the limits of the integrator output voltage does not depend on the breaker opening frequency. Using resistor R3, it can be set equal to 135°/45° according to the program recorded in the PROM. It is characteristic that a decrease (or increase) in this ratio is equivalent to an increase (or decrease) in the initial angle of the OZ with a simultaneous slight change in the slope of the dependence φ(N), as follows from formula (4).
If, for example, the signal/pause ratio is made equal to 130°/50°, then the programmed dependence will be reproduced by the synthesizer as f(N) with an initial angle of 11° rather than 6° and an increased slope, as in the case of a decrease in the GTI frequency by (135 ° - 130°)/135°=3.7%, because the PROM address code will decrease by the same amount. If the signal/pause ratio is greater than normal, say 140°/40°, then everything will move in the other direction. In comparison with the above example, for a 10% increase in frequency, to which the graphs in Fig. 4, here the change in slope is hardly noticeable.
For example, at the inflection point of the characteristic (at 2820 rpm), the OZ angle will decrease not by 4.2°, which was the maximum value, but only by 1.5°, while by reducing the initial angle the entire characteristic will shift by 5 °. This feature of the described signal converter creates a beneficial opportunity to electronically (using resistor R3) adjust the initial angle of the OZ in the case of operation of the synthesizer from a chopper by at least ±5...7° with an almost unchanged form of the dependence φ(N).
In addition to correcting the angle of the vision, this device allows you to adjust the slope of the characteristics of the vision, but only in the direction of decreasing steepness. The integrating circuit R2C1 is designed for this purpose, providing a time delay for switching the RS trigger relative to the moment of opening the breaker contacts, independent of the value of N. The delay time range is tз=0...0.7*R2*C1, and the delay angle phz = 180°tзN/30. With the indicated values of R2, C1, this amounts to up to 1.1° at 800 rpm, up to 3.9° at 2820 rpm and up to 8.2° at 6000 rpm. The possibility of introducing fz along with adjusting fn with a slight change in the steepness of the OZ characteristics leads to the conclusion that when working with a breaker, it is preferable to set the initial angle of less than 6° by turning the ignition distributor than vice versa. Then adjusting the fn using R3 towards an increase will lead to an increase in the steepness of the characteristic, and it can be reduced by introducing a delay. If unnecessary, the time delay circuit can be removed by connecting R1 directly to pin 6 of element DD8.2
An inevitable unpleasant consequence of using an op-amp is the need for a bipolar power supply. An example of a diagram of such an autonomous device is shown in Fig. 7.
Rice. 8. Schematic diagram of the common power supply of the automated electronic ignition unit (AEBZ) and the digital ignition timing regulator
An RC square-wave pulse generator with a frequency of 20...40 kHz is assembled on elements DD8.3, DD8.4. It controls transistor switches VT1, VT2, to the emitters of which two-link voltage multipliers are connected for each polarity. Voltage stabilization is carried out using resistors R16, R17 and zener diodes VD9, VD10.
If TsifRUOZ is intended to be used in conjunction with ABEZ, then it is advisable to manufacture a common power supply according to the circuit shown in Fig. 8.
The designations of elements found in the ABEZ are indicated in parentheses, and those underlined are those found in the synthesizer. Its advantages are based on overcompensated stabilization of the output voltages of the blocking generator, which includes transformer T1 (ABEZ) with additional windings V and V1. Thanks to overcompensation, there is even no need to stabilize the voltages of U4 and U5. All indicated voltage ratings are provided when the vehicle's on-board network voltage Ea changes from 6 to 18 V (in reality, this range is even wider in both directions).
It is characteristic that when Ea is less than 8...9 V, the current enters the coils L1 and (L3) through the diode VD25 (VD24 is closed), since the amplitude of the pulses (reverse stroke of the blocking generator) on the V winding is higher than this value, and with more voltage Ea - through diode VD24 (VD25 is closed). At the same time, the VD24 diode cuts off potential interference voltage pulses of negative polarity in the on-board network. When using a common power source in the ABEZ, you can remove the diode VD21 and resistor R38 by connecting the emitter VT12 to Upit 2 (+0.7 V). In addition, it is advisable to connect the common points of resistors R11 with R12 and the emitter VT5 with capacitor C3 of the synthesizer to Upit1. In this case, the consumption currents will be as follows:
along the Upit1 circuit (+ 7.7 V) less than 10 mA (without taking into account the current consumption of the synthesizer LED, which can be 0...12 mA);
along the Upit2 circuit (+0.7 V) less than 3 mA;
in circuit U3 (+ 6.2 V) less than 10 mA;
via circuit U4 (-15 V) up to 5 mA;
along circuit U5 (+15 V) 13...15 mA.
The digital regulator is structurally combined with an automated electronic ignition unit. All its parts are located on a separate printed circuit board (Fig. 9)
Made of foiled fiberglass laminate 1.5 mm thick, having the same dimensions as the boards of the mentioned block. It is installed on the supporting plate of the unit body along with two other boards edgewise and is also secured with screws using angle brackets. The microcircuit cases are glued to the board through fabric pads about 1 mm thick with the leads outward, i.e., from the surface of the board. The connections are made with PEL-1 0.12 wire directly “from leg to leg,” and diodes with their wire leads are also used as connecting elements. Only the power and ground buses are made of foil conductors. The corresponding IC pins are soldered to them using wire stands with a diameter of 0.5...0.7 mm. For other parts - transistors, diodes, capacitors and resistors - printed wiring is normal.
Load resistors PPZU (DD4) Rн1-Rн8 (15 k each) are installed on the foil side. To isolate it from it, pieces of whatman paper were used; the resistor leads were passed in pairs into four holes with a diameter of 1.5 mm, which were drilled between the housings DD2 and DD4. If pin 9 of the DD2.2 IC is connected to pin 10 of DD7, then the comparison of the output codes of the control unit and the PROM and the operation of DD2.2 will be gated by clock pulses.
Capacitors C1 - C3, C5 any type K10-7V, KLS, KM. All resistors are MLT or MT. As transistors VT1, VT2, VT4 you can use any KT315, KT342, KT3102 and the like, VT5 - KT361, KT209, KT3107 and similar with any letter indices. In place of VT3, a mid- or high-frequency transistor with a permissible pulse collector current of at least 200 mA is required. In addition to any KT209, KT208 (the best option), KT502, KT3107, etc. are suitable. Diodes are any of the KD520, KD521, KD522 series, but KD503, KD509 can also be used.
Coil L1, as in the ignition unit, should have an inductance of 5 ... 15 mH and a resistance of 40 ... 80 Ohms. If the synthesizer is supposed to work together with ABEZ, then it would be better to install the HL1 LED with a green glow, since the ignition unit already has yellow, orange and red.
The most desirable microcircuits for a synthesizer are the K564 series ICs, because in all electrical and operational parameters they are superior to the K561 series ICs, and in terms of the permissible temperature range (-60...+125 ° C) they are the most suitable (for the K561 series ICs only -45 ... + 85 °C). True, the use of ICs of the K564 series will add difficulties in installation - they have very thin soft leads, and the interval between them is half that of the ICs of the K561 series.
Programmable ROM ICs can be taken from any of the KR556 series, including those with a 4-bit output, selecting their composition so that there are 512 words X 8 bits (or 1024X8) to record one RAM characteristic. However, it makes no sense to create a memory capacity for more than 4 characteristics, taking into account the possibility of their shift along the N axis, and in the presence of a converter-corrector (see Fig. 5) - also along the angular axis OZ. Instead of these ROMs, you can also use reprogrammable LISMOS types, for example, K573RF2 (2048X8), which are better consistent with the CMOS structures of the K564 and K561 series ICs.
But with them there is a danger that due to self-erasing of information, unpredictable changes will appear in the recorded program in 3-5 years.
In the converter-corrector, instead of the specified dual operational amplifier K140UD20, it is even better to use the more heat-resistant microcircuit KM551UD2A (B) or the K140UD1, which has proven itself well in the ignition system of the VAZ-2108 (-09). However, many other options are also acceptable, for example two K140UD7 op-amps and even KR140UD1. An RS trigger and an RS generator (see Fig. 5 and 7) can, of course, be assembled not only using elements with “2 OR-NOT” logic. “2 AND-NOT” and a number of others are suitable. But in the proposed version, all the minimum necessary elements make up one body, which is not possible in the other version.
It should be especially noted that when installing ICs of the K561 or K564 series, it is imperative to strictly comply with the prescribed technical specifications in order to exclude the possibility of breakdown of their input circuits by electrostatic voltage.
In the synthesizer, you only need to adjust the GTI frequency. This is done by variable resistor R6 with the potentiometer R8 in the middle position. Everything else will certainly work normally if the elements are in good working order and properly wired. However, after assembling and checking the installation, it is necessary to check the supply voltage ratings and the performance of the transistors according to the “open-closed” principle. The operation of the counters (zeroing, counting), the compliance of the EEPROM output codes with the programming table and all other switchings, although it takes a long time, are simply checked using the step-by-step counting method. To do this, you need to shunt the signal buses F, F and “output 1” of the GTI to ground through resistors with a resistance of 10...30 k. After this, disconnect the first two from the ABEZ transistors, and the third from pin 10 of the DD7.3. Then, using one two-position toggle switch, connect the voltage U3 to either bus F or F, and through a button (or another toggle switch) apply the same voltage to the “output 1” bus.
Next, by setting the voltage U3 on bus F, which will correspond to the measuring interval, when turning the button on and off, you can check the operation of the counter, and by switching the toggle switch to the opposite state, the operation of the counter. Having thus established any codes at the counter outputs, you can check the operation of the PROM and the recorded program by simulating pulse power supply of the DD4 IC by briefly (up to 1 s) shorting the VT2 collector to ground. You can control the coincidence of the output codes of the PROM and the control unit by the voltage on resistor R9, on pin 11 of DD2.2 and on the collector VT1.
“Characteristics switch” OZ SA1 and potentiometer R8 are mounted together with SA1 and SA2 ABEZ on the steering column. To make it easy to estimate by touch the position of the potentiometer slide, i.e. the approximate value of the GTI frequency and, therefore, the shift of the OZ characteristic, a “beak” handle is mounted on its axis. The adjusting elements of the corrector - R3 and R2 - are located under the block casing, and the axes of these resistors are located “under the slot”. Balancing potentiometers are actually replaced by pairs of fixed resistors, in which one is selected during tuning.
By selecting the R18C3 circuit, the LED service indicator TsifRUOZ is adjusted to a rare but clearly visible flashing at 1500...2000 rpm.
To help a radio amateur, 1991
Literature
1. Tyufyakov A. Ignition system without secrets: Sat. Avtomobilist-86.- M.: DOSAAF, 1986.
2. Alekseev S. Shapers and generators on CMOS microcircuits. - Radio, 1985, No. 8, p. 31.
3. Alekseev S. Application of the K561 series microcircuit. - Radio, 1986, No. 11, p. 3. No. 12, p. 42.
4. Vorobyova N. One-time programmable ROMs of the KR556 series. Microprocessor tools and systems.-M.: GKVTI, 1987, No. 1, 2, 3.
5. Shcherbakov V., Grezdov G. Electronic circuits on operational amplifiers. Directory. - Kyiv, “Technology”, 1983.
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The economic, power and operational parameters of a car engine largely depend on the correct setting the ignition timing. Factory setting ignition timing is not suitable for all cases, and therefore it has to be adjusted by finding a more accurate value in the zone between the appearance of detonation and a noticeable decrease in engine power.
It is known that when deviating from the optimal ignition timing at 10 degrees, fuel consumption can increase by 10%. It is often necessary to significantly change the initial ignition timing depending on the octane number of gasoline, the composition of the combustible mixture and actual road conditions. The disadvantage of centrifugal and vacuum regulators used on cars is the impossibility of adjustment ignition timing from the driver's workplace while driving. The device described below allows such adjustment.
From devices similar in purpose electronic corrector characterized by simplicity of the circuit and a wide range of remote installation of the initial ignition timing. The corrector works in conjunction with centrifugal and vacuum regulators. It is protected from the influence of bouncing contacts of the breaker and from interference from the vehicle’s on-board network. In addition to correction ignition timing, the device allows you to measure the engine crankshaft speed. The described one differs from the digital corrector in that it provides smooth adjustment of the correction angle, contains fewer parts and is somewhat easier to manufacture.
Main technical characteristics Supply voltage. V 6...17 Current consumption when the engine is not running. And, with closed breaker contacts 0.18 with open breaker contacts 0.04 Frequency of triggering pulses. Hz... 3.3...200 Setting initial angle of OZ on the distributor, deg.... "20 Limits of remote correction of the angle of OZ. deg........ 13...17 Duration of delay pulse, ms : maximum.... 100 minimum.... 0.1 Duration of the output commutation pulse, ms...... 2.3 Maximum value of the output switched current... A... 0.22 Engine operation at installation angles specified by the corrector, possible if the pulse from the breaker is delayed for a while
T3=(Fr-Fk)/6n=(Fr-Fk)/180*Fn
where Фр, Фк - initial ignition timing, set by the distributor and corrector respectively; n - crankshaft rotation speed; Fn=n/30 sparking frequency.
Puc.1
Figure 1 shows, on a logarithmic scale, the dependence of the spark delay time on the crankshaft speed, calculated for different values of the initial ignition timing, set by the proofreader. This graph is convenient to use when setting up and calibrating the device.
Puc.2
In Fig. 2 shows the characteristics and limits of change of the current value ignition timing depending on the engine speed. Curve 1 is shown for comparison and illustrates this dependence for a centrifugal regulator with an initial setting ignition timing, equal to 20 degrees. Curves 2, 3, 4 are the resulting ones. They were obtained through the joint operation of a centrifugal regulator and electronic proofreader at installation angles of 17, 0 and -13 degrees.
The corrector (Fig. 3) consists of a trigger unit on transistor VT1, two standby multivibrators on transistors VT2, VT3 and VT4, VT5, and an output switch on transistor VT6. The first multivibrator generates a spark delay pulse, and the second controls the transistor switch.
Puc.3()
Let us assume that in the initial state the contacts of the breaker are closed, then the transistor VT1 of the starting unit is closed. The forming capacitor C5 in the first multivibrator is charged with current through the emitter junction of transistor VT2, resistors R11, R12 and transistor VT3 (the charging time of capacitor C5 can be adjusted by resistor R12). The forming capacitor C8 of the second multivibrator will also be charged. Since transistors VT4 and VT5 are open, VT6 will also be open and close the “Breaker” terminal of the ignition unit through resistor R23 to the housing.
When the breaker contacts open, transistor VT1 opens, and VT2 and VT3 close. The forming capacitor C5 begins to recharge through the circuit R7R8R14VD5R13. The parameters of this circuit are selected so that the recharging of the capacitor occurs much faster than its charging. The recharging speed is controlled by resistor R8.
When the voltage on capacitor C5 reaches the level at which transistor VT2 opens, the multivibrator returns to its original state. The more often the breaker contacts open, the lower the voltage capacitor C5 is charged and the shorter the duration of the pulse generated by the first multivibrator. This achieves an inversely proportional relationship between the spark delay time and the engine crankshaft speed.
The decay of the pulse generated by the first multivibrator triggers the second multivibrator through capacitor C7. It generates a pulse with a duration of about 2.3 ms. This pulse closes the transistor switch VT6 and disconnects the “Breaker” clamp from the housing and thereby simulates the opening of the breaker contacts, but with a delay of time t, determined by the duration of the pulse generated by the first multivibrator.
The HL1 LED informs about the passage of a pulse from the breaker sensor through the electronic corrector to the ignition unit. Resistor R23 protects transistor VT6 if its collector is accidentally connected to the positive wire of the vehicle’s on-board network.
The device is protected from bouncing of the breaker contacts by capacitor C1, which creates a time delay (about 1 ms) in the closing of the transistor VT1 after the breaker contacts are closed. Diodes VD1 and VD2 prevent the discharge of capacitor C) through the breaker and compensate for the voltage drop that occurs on the conductor connecting the engine to the car body when the starter is turned on, which increases operational reliability electronic proofreader while starting the engine. The device protects circuit VD8C9, zener diodes VD6, VD7, resistors R2, R6, R15 and capacitors C2, SZ, Sat from interference arising from the on-board network.
The crankshaft rotation speed is measured by the VD9VD10R25R26PA1 chain. The scale of this tachometer is linear, since the voltage pulses on the collector of transistor VT5 have a constant duration and amplitude provided by the zener diode V07. Diodes VD9, VD10 eliminate the influence of residual voltage on transistors VT5, VT6 on tachometer readings. The rotational speed is measured on the scale of a PA1 milliammeter with a full needle deflection current of 1...3 mA.
The corrector uses capacitors K73-17 - C1, C8, C9; K53-14-S2, S5; K10-7 - NW, C6; KLS - C4. C7. Resistor R8 - SPZ-12a, R12 - SPZ-6, R23 - made up of two MLT-0.125 resistors with a resistance of 10 Ohms. Diodes KD102B, KD209A can be replaced with any of the KD209 or KD105 series; KD521A - to KD522. KD503, KD102, KD103, D223 - with any letter index. Zener diodes KS168A, D818E can be replaced with others with the appropriate stabilization voltage. Transistors KT315G can be replaced with KT315B, KT315V, KT342A, KT342B; KT361 G - on KT361B, KT361V, KT203B, KT203G; KT815V - on KT608A, KT608B.
The device parts are mounted on a printed circuit board made of foil-coated fiberglass laminate 1 mm thick. The drawing of the printed circuit board and the arrangement of parts on it are shown in Fig. 4.
Figure 4
To set up the device, you need a power supply with a voltage of 12...14 V, designed for a load current of 250...300 mA. Between the conductor from resistor R23 and the positive terminal of the power source, a resistor with a resistance of 150...300 Ohms with a power dissipation of 1-2 W is connected for the setup period. A breaker simulator - an electromagnetic relay - is connected to the input of the device. Use an open pair of contacts; one of them is connected to the common point of resistors R1, R2, and the second to the common wire. The relay winding is connected to a generator that provides relay switching with a frequency of 50 Hz. In the absence of a generator, the relay can be powered from a step-down transformer connected to the network.
After turning on the device, check the voltage on the zener diode VD6 - it should be 6.8 V. If the corrector is assembled correctly, then the HL1 LED should light up when the breaker simulator is operating.
A DC voltmeter with a voltage scale of 2...5 V is connected in parallel to transistor VT3, with a current of total needle deflection of no more than 100 μA. The resistor R8 is brought to the extreme right position. When the chopper simulator is running, the trimmer resistor R12 is used to set the voltage on the voltmeter scale to 1.45 V. At this voltage, the duration of the delay pulse should be equal to 3.7 ms, and the initial angle 03 should be -13 degrees. In the middle position of the resistor R8 slider, the voltmeter should show a voltage of 1 V, which corresponds to the zero initial angle of the OZ, and in the leftmost position 0.39 V - 17 degrees (see table).
The most simple (but not entirely accurate) corrector can be set up as follows. The resistor motor R12 is set to the middle position, and the resistor motor R8 is rotated by a third of the full angle of rotation from the position of minimum resistance. By turning the ignition distributor housing 10 degrees in the direction of earlier ignition (against the movement of the shaft), start the engine and use resistor R12 to achieve stable idle operation. To calibrate the initial angle regulator scale, you need a car strobe light.
The tachometer is calibrated by adjusting resistor R26 (at a trigger pulse frequency of 50 Hz, the microammeter needle should show 1500 min"). If the tachometer is not needed, its elements do not need to be mounted.
To connect the corrector, a five-pin socket (ONTs-VG-4-5/16-r) is installed in a place convenient for the driver, the contacts of which lead to conductors from the on-board network, breaker, ignition unit, housing and tachometer (if provided). The corrector, mounted in a casing, is installed inside the car, for example, near the ignition switch.
The corrector can be used in conjunction with the electronic ignition unit described in. It can work with other SCR ignition systems with both pulsed and continuous energy storage on a capacitor. In this case, as a rule, no modifications to the ignition units associated with the installation of the corrector are required.
Literature:
1. Saving fuel. Ed. E.. P. Seregina. - M.: Military Mat.
2. Sinelnikov A. EK-1 device. - Behind the wheel. 1987, No. 1, p. thirty.
3 Kondratyev E. Ignition timing regulator. - Radio, 1981, No. 11. p. 13-15.
4. Moiseevich A. Electronics against detonation. Behind the wheel, 198В No. 8. p. 26.
5. Biryukov A. Digital octane corrector. - Radio. 1987, No. 10, p. 34-37.
6. Bespalov V. Electronic ignition unit. - Radio. 1987, No. 1, p. 25-27.
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