US3577963A

US3577963A - Control for internal combustion engines

Info

Publication number: US3577963A
Application number: US730053A
Authority: US
Inventors: Rudolf Bechmann
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 1967-05-27
Filing date: 1968-05-17
Publication date: 1971-05-11
Anticipated expiration: 1988-05-11

Abstract

A distributor for internal combustion engines having a centrifugally operated and a vacuum operated spark timing control with a switch in the primary circuit of an ignition coil operated by a throttle valve and the switch connected to a circuit breaker system controlled by centrifugal operation and a further circuit breaker system connected and influenced by a vacuum operated control.

Description

United States Patent References Cited UNITED STATES PATENTS 7/1929 Bohlman......................

71 l MW 31 1,897,704 2/1933 Mallory 1,992,383 2/1935 Mal1ory 2,103,348 12/1937 Boyce......

Primary Examiner-Laurence M. Goodri e Attorney-Watson, Cole, Grindle and Watson o. 6 n mu mm y [54] CONTROL FOR INTERNAL COMBUSTION ABSTRACT: A distributor for internal combustion engines having a centrifugally operated and a vacuum operated spark n m m mn m NC 5 .m ElUF HUM HUB

coNTRol, so: mmrtnAL-coMBusTroN ssc'mss This invention relates to a distributor for the engines of motor vehicles with a centrifugally operated and a vacuum operated spark control.

Known distributors of this type have only one circuit breaker upon which the centrifugally operated and the vacuum operated spark controls both act together. For reasons which are to .be found in the type of construction of the two control elements, it is not possible in the case of this arrangement to achieve delayed firing during idling, of the motor which is desirable for the purpose for good combustion, and at the same time to achieve an irregular or sudden adjustment to a spontaneous ignition during acceleration. Since preference is given to good acceleration above all in the case of opening of the throttle valve from the idling position, a relatively high advance sparking is selected as the basic setting. Thus, one must consider in the case of idling of the motor with an advance sparking that is somewhat too high and which in turn results in too high an idling speed. ln order to lower the idling speed, the throttle valve therefore is set to an almost complete closing position. The consequence of this is that the engine in the idling state, but above all under thrust, will obtain, because the air supply now is much too small with simultaneously too little content, a super rich mixture, which, being burned incompletely, reaches the open air through the exhaust.

An object of the invention resides in making an ignition adjustment for the purpose of decontamination of the exhaust gas in such a manner that during idling and under thrust, one will obtain a good combustion and complete burning of the fuel without adversely affecting the running behavior as a result thereof.

According to the invention, the solution of the problem consists in that a switch operated by the throttle valve or its rod system, isprovided in the primary circuit of the ignition coil, by which switch, with the throttle valve closed up to the idling position, only the circuit breaker system influenced by the centrifugally operated control, is switched on and in every open position of the throttle valve another circuit breaker system influenced only by the vacuum operated control is switched in.

Appropriately, the area of adjustment of the centrifugally operated adjustment amounts to after to 30 before the upper dead center of the crankshaft and the range of the vacuum operated control amounts to 10 before to 35 before the upper dead center of the crankshaft. As a further object of the invention, both circuit breaker systems have been arranged one above the other in the distributor housing and they have one common driving shaft carrying the two cams.

As a result of this invention, it will be possible to make the basic setting of the two spark controls independent of one another and staggered in relation to one another, as desired. The firing point in idling therefore can be set to late," so that the throttle valve can be opened further, without increasing the idling speed as against an idling speed in the case of spontaneous ignition. As a result thereof, in the case of all operating states while traveling with an idling position of the throttle valve, an improved filling of the cylinders with an increased share of air in the mixture will be achieved. In connection with the centrifugally operated control which becomes effective at higher speeds,'one will achieve good combustion not only during idling but also under thrust and the omission of exhaust gases will be decreased to tolerable values. On the other hand, the vacuum operated control can be set to an optimum spontaneous ignition independently of what has been stated so that in the case of a transition from idling to acceleration and uniform travel, the ignition will switch over spontaneously from "late to early," and especially good values of acceleration, which cannot be achieved otherwise, and transitions will be achieved. 1

Further objects will be apparent from the following description when considered in connection with the accompanying drawing which shows the structure as a perspective view with wiring connections.

The distributor shown schematically in FIG. I, with its conprising two cams driven in timed tacts 1,2, 3 and 4 in the distributor head, leading to the spark plugs, has two circuit breakers 5 and'6 arranged one above the other, which are operated by

cams

7 and 8 respectively seated on the distributor shaft. For each of the circuit breakers 5 and 6 a separate ignition control of the design used in the trade, has beenprovided and to be sure, a centrifugally operated control 9 for the upper breaker 5 and for the lower breaker 6 a vacuum operated control 10. in the case of the centrifugally operated control 9, the adjustment takes place in a known manner by two centrifugal weights 1], which adjust, upon increasing speed, a driver 12 in the direction of rotation, by means of cam 7 which is rotatable on the distributor shaft. The vacuum box of the vacuum operated control 10, has been attached as is customary by a pipe connection 13 to the intake pipe 14 of the carburetor; Upon opening the throttle 15, the vacuum in the suction pipe of the engine will act on the membrane or diaphragm 16 of the control 10, which membrane will rotate a plate 17 with the circuit breaker 6 located thereon counter to the rotational direction of the cam 8 by means of a pull rod attached to said membrane and, as a result thereof, will increase the advance sparking.

The cables of the two circuit breakers 5 and 6, which have been switched in parallel, lead to a switch 21 located in the primary circuit of the ignition coil 20, which switch is operated by the lever of the throttle valve 15 and has two positions. In the case that the throttle valve 15 is closed, only the circuit breaker 5 with the centrifugally operated control 9, has been switched on and in the case of an opened throttle 15 only the circuit breaker 6 with the vacuum-operated control 10 has been switched on.

in the diagram according to FIG. 2, the adjusting curve F of the centrifugally operated control 9 (basic setting 10 after upper dead center, adjusting range up to 30 before upper dead center of the crankshaft) and the full load adjusting curve U of the vacuum-operated control 10 (basic setting 10 before upper dead center, adjusting range up to 35 before upper dead center of the crankshaft) have been plotted above the engine speed or motor revolutions n. The idling speed has been designated with n,, r.p.m. In the case of opening of the throttle 15, the ignition is spontaneously switched over from the basic setting of 10 after the upper dead center of the centrifugally operated control 9 to the basic setting of 10 before upper dead center of the'vacuum-operated control 10. The ignition setting will then, in the case of further acceleration and in the case of level travel, and as long as the throttle valve 15 remains opened, follow the course of the curve U of the vacuum-operated control 9. By decreasing the gas and up to closing of the throttle 15, one shifts back to the centrifugally operated control 9. The ignition setting will then change in the case of thrusts of the vehicle (delay or else acceleration in the case of downhill travel) in correspondence with the course of the adjusting curve F.

lclaim:

1. An ignition distributor for a spark ignition engine comrelation with the engine, a pair of circuit breakers operated independently each of them by one of said cams, engine speed responsive means connected with one of said cams to retard the timed opening of the first of said circuit breakers with decreases in engine speed, a vacuum-operated control connected to said distributor and operated by pressures sensed in the induction system of said engine to adjust the timed opening of the second of said circuit breakers according to engine load and speed throughout a range of throttle open positions in which timed opening of the second of said circuit breakers is advanced with respect to the timing of the first when the engine is idling with the throttle closed, parallel circuits connecting each circuit breaker with the primary of the ignition coil, switch means in each of said parallel circuits, and means for operating said switch means to close one of said parallel connected circuits to the first said circuit breaker and open the other with the throttle closed to idle positions and to close the other of said parallel connected circuits to the second said circuit breakerand open the other with the throttle in the said range of open positions.

Claims

1. An ignition distributor for a spark ignition engine comprising two cams driven in timed relation with the engine, a pair of circuit breakers operated independently each of them by one of said cams, engine speed responsive means connected with one of said cams to retard the timed opening of the first of said circuit breakers with decreases in engine speed, a vacuumoperated control connected to said distributor and operated by pressures sensed in the induction system of said engine to adjust the timed opening of the second of said circuit breakers according to engine load and speed throughout a range of throttle open positions in which timed opening of the second of said circuit breakers is advanced with respect to the timing of the first when the engine is idling with the throttle closed, parallel circuits connecting each circuit breaker with the primary of the ignition coil, switch means in each of said parallel circuits, and means for operating said switch means to close one of said parallel connected circuits to the first said circuit breaker and open the other with the throttle closed to idle positions and to close the other of said parallel connected circuits to the second said circuit breaker and open the other with the throttle in the said range of open positions.