Internal-combustion engines – High tension ignition system – Power supply – ignition coil primary – and interrupter element...
Utility Patent
1999-09-07
2001-01-02
Kwon, John (Department: 3747)
Internal-combustion engines
High tension ignition system
Power supply, ignition coil primary, and interrupter element...
C315S2090SC
Utility Patent
active
06167876
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a circuit arrangement for an ignition output stage, in particular for an ignition circuit of a motor vehicle.
BACKGROUND INFORMATION
Low-side ignition circuits and high-side ignition circuits are conventional driving circuit arrangements for an ignition circuit. Multiple Darlington transistor stages (referred to below as Darlingtons) which drive a primary winding of an ignition coil are normally used as power switching elements for the ignition circuits. A distinction is made between low-side ignition and high-side ignition, depending on whether the primary winding is driven by the Darlington collector (low side) or the Darlington emitter (high side).
An ignition circuit which uses a p-n-p Darlington whose collector is connected to ground is described in German Patent No. 37 35 631.3. The emitter is connected to the positive terminal of a voltage source via the primary winding. Because the Darlington base is known to go to negative reverse voltage (blocking voltage) at turn-off, the driving circuit must be isolated from this voltage. The use of an n-p-n driving transistor for this purpose is described in German Patent 37 35 631.3.
SUMMARY OF THE INVENTION
The driving circuit according to the present invention having includes an advantage that the driving circuit can be isolated from a negative reverse voltage present at the base of the Darlington when the latter is turned off, at the same time enabling the decoupling element to be integrated into the Darlington. The provision of an n-p-n Darlington whose collector is connected to the positive terminal of a voltage source and whose emitter is connected to a first terminal of the primary winding of the ignition coil, with the second terminal of the primary winding being connected to ground and the Darlington being driven by a decoupling element, makes it possible to assemble the entire ignition output stage cost-effectively and with simple manufacturing techniques, in particular due to the ability inherent in the circuit arrangement to integrate the Darlington, the decoupling element, and the entire driving circuit into a monolithically integrated component. The driving circuit according to the present invention is further has a highly reliable ignition output stage when exposed to thermal stresses which occur under extreme operating conditions.
An especially advantageous of the present invention is the fact that the ability to integrate the decoupling element into an n-p-n Darlington considerably simplifies the electrical and thermal coupling of the ignition output stage with a heat sink connected to ground. The negative blocking voltage of around 300 to 400 V, which arises upon turning off of the Darlington, thus no longer needs to be insulated against a ground heat sink. It can therefore be advantageous to place the ignition output stages, a suitable number of which is provided, depending on the number of cylinders in the internal combustion engine to be driven, in a compact ignition system, since complicated measures to provide insulation between the collectors of the individual Darlingtons and against the ground heat sink are no longer necessary. Because all of the Darlington collectors can be connected together to a voltage bus attached to the positive terminal of the voltage source, this voltage bus alone has to be insulated against ground. This can be done with little effort, due to the relatively low voltage that is present, on the order of 14 V.
REFERENCES:
patent: 4124009 (1978-11-01), Hill et al.
patent: 4462356 (1984-07-01), Hirt
patent: 4515118 (1985-05-01), Haubner et al.
patent: 4738239 (1988-04-01), Haines et al.
patent: 5529046 (1996-06-01), Werner et al.
patent: 5634453 (1997-06-01), Taruya et al.
patent: 5970965 (1999-10-01), Bentel et al.
patent: 3 735 631 (1989-05-01), None
Meinders Horst
Qu Ning
Uebele Manfred
Kenyon & Kenyon
Kwon John
Robert & Bosch GmbH
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