DE3341014A1 - IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES - Google Patents

Description

R- 19055

3.11.19Ö3 Li / Wl

ROBERT BOSCH GMBH, TOOO Stuttgart 1

Ignition system for internal combustion engines
State of the art

The invention is based on an ignition system according to the preamble of the main claim. It is (according to DE-OS 32 08 2β2) an ignition system located in this direction is already known, but in which the means for compensating for the self-adjustment are relatively complex in terms of circuitry. Here is to be understood under self-adjustment that - under Relation to a certain switching threshold of the threshold value switch - the angle of rotation section by which the crankshaft moves of the internal combustion engine between a fixed angle mark and the switch-on time of the threshold switch turns, turns changes with speed. This sometimes ensures that the ignition energy is stored and that the '. Cattle process (ignition point) has a disruptive effect.

Advantages of the invention

The measure according to the invention can be relatively easily compensate for the Sigen adjustment. Included is not only the switching threshold of the threshold switch shifted over the speed in the sense of compensation,

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but also at the same time a glitch suppression is achieved.

In the subclaims are advantageous measures for indicated the implementation of the invention.

drawing

An exemplary embodiment of the invention is shown in circuit form in the drawing and in the description below explained in more detail.

Description of the embodiment

The ignition system shown in the drawing is intended for an internal combustion engine, not shown, of a motor vehicle, also not shown. This ignition system is fed from a direct current source 1, which can be the battery of the motor vehicle. At the power source 1, a line 2 connected to ground extends from the negative pole and a supply line h containing an operating switch (ignition switch) 3 extends from the positive pole. The supply line 4 is the starting point for a circuit branch which initially leads via the primary winding 5 of an ignition coil β and then via an electronic interrupter T to the ground line 2. The electronic interrupter 7 is formed by the emitter-collector path of an (npn) end transistor 8, the emitter facing the ground line 2. The secondary winding 9 belonging to the ignition coil 6 is connected with its one winding end to the connection between the primary winding 5 and the electronic interrupter 7 and with its other winding end via at least one ignition

33410H

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Plug 10 connected to the ground line 2.

The base of the output transistor 8 is connected to the collector of an (npn) driver transistor 11 and to the supply line U via a resistor 12. The driver transistor 11 has its emitter connected to the ground line 2 and its base connected to the output 13 of a threshold switch \ h. In the preferred case, the threshold switch 1 k, which operates in the manner of a Schmitt trigger, is to be formed by an operational amplifier 15. The operational amplifier 15 receives its supply voltage via the connections 16, 17. The inverting input (-) belonging to the operational amplifier 15 is connected to a reference voltage Ub ₅ which is tapped at the common connection point i8 of two resistors 19s 20. These two resistors 19 ₅ 20 form a voltage divider located between the supply line h and the ground line 2. A connection originates from the non-inverting input (+) of the operational amplifier 15, which first leads to the ground line 2 via a resistor 21 and then via a signal generator 22 operating in the manner of an alternating current generator.

A positive feedback branch 23 provided is connected on the one hand to the non-inverting input (+) of the operational amplifier 15 and on the other hand to the output 13 of the operational amplifier 15. This positive feedback branch 23 has a capacitive component 2k .

In the preferred case, there are at least 23 in the positive feedback branch an ohmic resistor 25 and at least one ohmic resistor 26 and a capacitor 27 existing series circuit connected in parallel to each other .

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With a decoupling resistor is referred to.

The ignition system just described has the following mode of operation :

As soon as the operating switch 3 is closed, the system is ready for use. It is now assumed that the control signal provided by the signal generator 22 has reached the lower switching threshold of the threshold value switch formed by the operational amplifier I5 and has switched off this threshold value switch. Thereupon the output 13 should at least almost assume the potential of the ground line 2 and bring the emitter-collector path of the driver transistor 11 into the blocking state. This has the consequence that the electronic interrupter 7 formed by the emitter-collector path of the end transistor 8 assumes the current conducting state and allows current to flow through the primary winding 5 of the ignition coil 6. Energy for the next ignition process is now stored in the ignition coil 6. After the control signal supplied by the signal generator 22 has exceeded its negative peak value, the switch-on threshold of the threshold value switch \ k is finally reached in the subsequent positive half-cycle. When the threshold switch 1U is switched on, the output 13 at least almost again assumes the potential of the supply line h , whereupon the emitter-collector path of the driver transistor 11 is current-permeable and the electronic interrupter 7 formed by the emitter-collector path of the end transistor 8 is blocked, As a result, the current conducted through the primary winding 5 is interrupted and a high-voltage pulse is induced in the secondary winding 9, which causes an electrical flashover (ignition spark) on the spark plug 10.

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The value of the resistors 19, 20 thresholds for the location of the switching is essential. and the ratio of the values of the positive feedback resistor 25 and the resistor 21 for the static switching hysteresis. With the help of the series circuit consisting of the resistor 26 and the capacitor 27, the dynamic positive feedback ensures that the angle of rotation that the crankshaft of the internal combustion engine passes through between a fixed angle mark and the switching on of the threshold value switch 1 k , when the speed changes, at least almost remains constant. At the same time, by using the series circuit consisting of the resistor 26 and the capacitor 27, increased insensitivity to interference is achieved in the control of the ignition system.

Claims (1)

R. 19055 November 3, 1983 Li / Wl ROBERT "BOSCH GMBH, TOOO Stuttgart 1 Expectations M J Ignition system intended for internal combustion engines, which can be controlled by an inductive signal transmitter and a threshold value switch connected downstream of this signal transmitter, means for compensating for the self-adjustment being used, characterized in that the threshold value switch (1U) has a positive feedback branch (23) with a capacitive component (2k) having. 2. Ignition system according to claim 1, characterized in that in the positive feedback branch (23) at least one ohmic Resistor (25) and consisting of at least one ohmic resistor (26) and a capacitor (27) Series connection are connected in parallel to each other. 3. Ignition system according to claim 1 and 2, characterized in that the threshold switch (1 k ) is formed by an operational amplifier (15) which has its inverting input (-) at a fixed reference voltage (Ub), which is also not at his inverting input (- ") receives the control signals of the signal generator (22) and finally connected to the non-inverting input (+) on the one hand and the output (13) on the other hand, the positive feedback branch (23)