GB2036864A

GB2036864A - Automatic Control of Engine Idling Speed

Info

Publication number: GB2036864A
Application number: GB7941342A
Authority: GB
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1978-11-30
Filing date: 1979-11-30
Publication date: 1980-07-02
Also published as: FR2442969A1; DE2948151A1; GB2036864B; JPS5575547A

Abstract

The engine intake air flow is increased by opening a by-pass valve 12 or a carburettor throttle valve (16), Fig. 2 (not shown), when the engine speed falls below a predetermined valve. The signal processor may be a micro computer. <IMAGE>

Description

SPECIFICATION An Antistalling Device for an Engine The present invention relates to an antistalling device for an engine to prevent it from stalling.

An engine for an automobile often stalls when its rotating speed rapidly lowers as at the moment of connecting of a clutch in starting of the engine.

Such an engine stall can be prevented by increasing intake air flow just as an engine is about to stall. In order to avoid an engine stall, therefore, a driver has trodden an accelerator pedal to increase the intake air flow when the engine idling becomes unstable. The prevention of the engine stall has been effected by an operation of the accelerator pedal relying upon his sense in this manner, so that the driving operation has become complicated and a quick operation for preventing the engine stall has been very difficult for an unskilled driver.

The ISC (idle speed control) device employing a feed back system has been proposed wherein an idling speed of an engine is detected and intake air flow is controlled or increased when the detected idling speed becomes equal to or lower than a determined speed. With such a control device employing the feed back system, if the control device is adjusted so as to become higher in gain for the purpose of obtaining a higher responsibility, there is a tendency of the control device to be unstable resulting in hunting, so that it cannot be excepted for such a control device to improve its responsibility. Accordingly, this device is unsatisfactory to prevent an engine stall resulting from a rapid lowering of engine rotating speed.

It is an object of the invention to provide an improved antistalling device for an engine which overcomes all the problems above described.

It is another object of the invention to provide an antistalling device for an engine which automatically increases its intake air flow to prevent the engine from stalling when its rotating speed lowers less than a determined speed.

The invention will be more fully understood by referring to the following detailed specification and claims taken in connection with the appended drawings.

Fig. 1 illustrates one embodiment of the invention; Fig. 2 shows another embodiment of the invention; and Fig. 3 illustrates one example of arithmetic flow chart which may be used in the device according to the invention.

Referring to Fig. 1 illustrating one embodiment of the present invention, a rotating speed sensor 1 produces signals corresponding to rotating speeds of an engine, which are shaped in a wave form shaping circuit 2 from which the shaped signals S, are supplied to a counter 4 which counts the signals S1 and is reset each time when a clock signal is supplied to the counter 4 from a clock signal generator 3 at a determined interval.

Outputs of the counter 4 are, therefore, digital signals S2 corresponding to the rotating speeds of the engine. An arithmetic unit 5 converts the signals S2 into signals indicating the rotating speeds of the engine and the outputs of the unit 5 are supplied to a comparator 6.

On the other hand, a memory 7 stores a determined rotating speed of the engine (which tends to stall at a rotating speed slower than the determined speed). The comparator 6 compares the signal S2 converted to indicate the engine speed with a signal read from the memory 7 and produces a driving signal S3, if the signal S2 is less than the signal from the memory. The driving signal S3 is supplied through an output circuit to a solenoid valve 9. In case of using micro computer, the arithmetic unit 5 and comparator 6 may be incorporated in one processor.

Upstream and downstream portions of a throttle valve 11 provided in an inlet channel 10 of the engine are connected by a bypass 14 including a negative pressure responsive valve 12. As the solenoid valve 9 is normally closed, an intake negative pressure is applied to the negative pressure responsive valve 12 connected between a negative pressure tube 13 and solenoid valve 9, so that the negative pressure responsive valve 12 is normally closed.

When the solenoid valve 9 is opened by the driving signal S3 supplied thereto, the intake negative pressure escapes into the atmosphere to open the negative pressure responsive valve 12 whereby air is supplied through the bypass 14 to the engine. As the result, the suction air is increased to raise the engine rotating speed thereby preventing the engine from stalling.

The embodiment shown in Fig. 1 is preferable for an engine equipped with a fuel injection system.

Fig. 2 illustrates another embodiment of the invention, wherein like components have been designated by the same reference numerals.

Referring to fig. 2, an inlet channel 1 5 of an engine is provided with a throttle valve 1 6 having a shaft 1 7 to which is connected a rod 19 of a negative pressure responsive open and close device 20 through an arm 1 8.

As a negative pressure is supplied to the device 20 through a negative pressure tube 22, when the solenoid valve 9 is closed, a diaphragm 21 of the device 20 is attracted to the right as viewed in Fig. 2 and the rod is thus attracted in the same direction to close the throttle valve 1 6.

However, when the solenoid valve 9 is opened by supplying the drive signal S3 from the output circuit 8, the intake negative pressure escapes into the atmosphere, so that the diaphragm 21 and rod 19 are pushed by a spring toward the left as viewed in Fig. 2, with the result that the throttle valve 1 6 is opened to increase the intake air. In case of a fuel injection system when the intake air is increased, fuel is also increased through a fuel injection valve by an amount calculated corresponding to the increased air. In case of a carburetor system, fuel is increased by suction corresponding to the increased air. In any case, the fuel mixture is increased.

The embodiment shown in fig. 2 is preferable for an engine equipped with a carburetor.

Fig. 3 is an arithmetic flow chart in case of the arithmetic unit 5 and the comparator 6 constucted by a micro computer.

As can be seen from the above description, when the rotating speed of an engine lowers to a valve less than a determined speed, the intake air is automatically increased to prevent the engine stalling, thereby enabling a driver to disregard an engine stalling and avoiding it in the event of an unskilled driver.

Moreover, the device according to the invention permits rotating speeds of an engine in excess of a normal idling speed when the intake air is increased to prevent an engine stalling, so that it does not cause any hunting in a rapid control which would occur in the ISC device in feed back system maintaining an idling speed constant.

Accordingly, the device according to the present invention can effectively prevent the engine stalling. Furthermore, the function of the present invention can be given to an existing engine equipped with an ISC device using computers only by changing its program (to temporarily increase the intake air only when the rotating speed becomes less than a determined value).

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in from and details can be made therein without departing from the spirit and scope of the invention.

Claims

1. An antistalling device for an engine comprising first means detecting rotating speeds of the engine, second means producing signals when said rotating speeds become less than a predetermined value and third means increasing intake air flow for the engine when the third means receives said signals from said second means.

2. An antistalling device as set forth in claim 1, wherein said third means comprises a negative pressure responsive valve in a bypass connecting upstream and downstream portions of a throttle valve provided in an inlet channel and a solenoid valve for supplying and shutting off intake negative pressure to said negative pressure responsive valve.

3. An antistalling device as set forth in claim 1, wherein said third means comprises a negative pressure responsive open and close device connected to a shaft of a throttle valve and a solenoid valve for supplying and shutting off intake negative pressure to said negative pressure responsive open and close device.

4. An antistalling device as set forth in claim 1, wherein said first means comprises a rotating speed sensor for producing signals corresponding to rotating speeds of the engine, a clock signal generator for generating clock signals at a determined interval, a wave form shaping circuit for shaping said signals corresponding to rotating speeds to facilitate processing them, a counter for counting said signals from said waveform shaping circuit and being reset each time when receiving said clock signal from said clock signal generator and an arithmetic unit for converting said signals from said counter into signals indicating the rotating speeds of the engine, said second means comprises a memory for storing a predetermined rotating speed of the engine and a comparator for comparing said signals from said arithmetic unit with signals read from said memory and producing a driving signal if the signal from the arithmetic unit is less than the signal from said memory, and said third means comprises a negative pressure responsive valve in a bypass connecting upstream and downstream portions of a throttle valve provided in an inlet channel and a solenoid valve for supplying and shutting off intake negative pressure to said negative pressure responsive valve.

5. An antistalling device as set forth in claim 1, wherein said first means comprises a rotating speed sensor for producing signals corresponding to rotating speeds of the engine, a clock signal generator for generating clock signals at a determined interval, a wave form shaping circuit for shaping said signals corresponding to rotating speeds to facilitate processing them, a counter for counting said signals from said wave form shaping circuit and being reset each time when receiving said clock signal from said clock signal generator and an arithmetic unit for converting said signals from said counter into signals indicating the rotating speeds of the engine, and said second means comprises a memory for storing a predetermined rotating speed of the engine and a comparator for comparing said signals from said arithmetic unit with signals read from said memory and producing a driving signal if the signal from the arithmetic unit is less than the signal from said memory, and said third means comprises a negative pressure responsive open and close device connected to a shaft of a throttle valve and a solenoid valve for supplying and shutting off intake negative pressure to said negative pressure responsive open and close device.

6. An antistalling device as set forth in claim 4 or 5, wherein said arithmetic unit and said comparator are constructed by a micro computer.

7. An antistalling device for an engine substantially as hereinbefore described with reference to the accompanying drawings.