GB2092779A

GB2092779A - Device for controlling the engine revolutions of an i.c. engine

Info

Publication number: GB2092779A
Application number: GB8200039A
Authority: GB
Original assignee: Mannesmann VDO AG
Current assignee: Mannesmann VDO AG
Priority date: 1981-02-05
Filing date: 1982-01-04
Publication date: 1982-08-18
Also published as: FR2499155A1; FR2499155B1; DE3103928A1; DE3103928C3; DE3103928C2; GB2092779B

Abstract

A desired value transmitter (1) coupled to an accelerator pedal (2) supplies a comparator (3) with a desired signal corresponding to an engine speed. A speed transmitter (4) supplies the comparator (3) with an actual signal corresponding to the instantaneous actual engine speed. An electronic control system (6) receives a signal representative of the difference of desired and actual signals. A driver circuit (7) is controlled from the control system such that in the event of the desired signal being equal to the actual signal a throttle valve (8) is retained in a position proportional to the desired signal. In the event of a higher desired signal than actual signal, the throttle valve (8) is opened further. In the event of a higher actual signal than the desired signal, the comparator (3) supplies a closure signal to magnetically operated valves (9) in the fuel supply lines (11) to injection nozzles (10) associated with respective cylinders of the internal combustion engine. <IMAGE>

Description

SPECIFICATION Device for controlling the engine revolutions of an internal combustion engine The present invention relates to a device for controlling the engine revolutions (R.P.M.) of an internal combustion engine. One known type of device has: a desired value transmitter from which there is fed to a comparator a desired signal corresponding to an engine speed; a speed transmitter from which there is fed to the comparator an actual value corresponding to the particular actual engine speed; a control system tc which is fed a differential signal formed by the comparator from the difference of desired signal and actual signal; an actuator element controlled by the control system.In such a system, when the magnitude of desired signal and actual signal are equal, a throttle valve is retained in a position proportional to the desired signal and, when the desired signal is larger than the actual signal, the throttle valve is opened in order to increase the engine revolutions and thus equate the two signals. With the aid of such a device for controlling the engine revolutions it is possible to keep the speed of the vehicle constant independent of the particular travel parameters.

However, such devices have the disadvantage thai control is effected only with reference to a desired value which is preset for a particular set of conditions.

It is an object of the present invention to overcome the above disadvantage in the known devices for controlling the engine revolutions.

According to the present invention there is provided a device for controlling the engine revolutions of an internal combustion engine including: a desired value transmitter coupled to the accelerator pedal of the engine, said transmitter supplying a desired signal corresponding to the engine speed; a speed transmitter supplying an actual signal corresponding to the instantaneous engine revolutions; a comparator for comparing the desired signal with the actual signal; an electronic control circuit fed with the differential signal output from the comparator, said differential signal being the difference between the desired signal and the actual signal; a driver circuit controllable by the control circuit for adjusting the position of the throttle valve of the engine; and means also operable from the output from the comparator for shutting off the fuel supply to the engine; whereby in the event that the values of the desired signal and the actual signal are equal, the throttle valve is maintained in a position proportional to the desired signal; in the case where the desired signal is higher than the actual signal, the throttle valve is adjusted in the open direction; and in the event where the actual signal is higher than the desired signal, a closure signal is supplied by the comparator to shut off the fuel supply to the engine.

In this manner, in each optional position of the accelerator pedal between no-load running and full acceleration, an engine speed increased by thrust operation relative to the momentarily adjusted desired value is controlled-down by simple means through the required desired speed, which control results in the saving of fuel.

Since a part of the components of the device are already available in the case of so-called electrical accelerator pedals, no great additional expenditure is necessary.

If, in the case where the actual signal is higher than the desired signal, the driver circuit adjusts the throttle valve in the opening direction, in which case preferably the throttle valve is adjustable to the maximum opening position. This has the advantage that the suction process or the engine takes place unthrottled, thus, leading to a thrust-phase prolongation and therewith to a further fuel saving.

Preferably, the signals are electrical analog signals, so that no complicated mechanical adjusting devices are required. In this manner, the individual element of the device can be fitted at any optional position in the motor vehicle, this being advantageous in the case of the known installation space problems in motor vehicles.

If the engine is a fuel-injection engine, the fuel supply shutting off means is arranged in each fuel line extending to an injection nozzle associated with a cylinder of the engine.

The fuel supply shutting off means may be a magnetically-operated valve, which is energized in the case of a higher or equal desired signal relative to the actual signal.

The present invention will now be described in greater detail by way of example with reference to the accompanying drawing, wherein the sole figure is a block diagram of one preferred device for controlling the engine revolutions of an internal combustion engine.

The device for controlling the engine revolutions of an internal combustion engine includes a desired value transmitter 1 comprising a potentiometer which is adjustable by means of a control element in the form of an accelerator pedal 2.

The electrical signal output from the desired value transmitter 1 is transmitted as desired signal to a comparator 3.

The actual signal is fed to the comparator 3 from a speed transmitter 4 which outputs an electrical signal proportional to the actual speed of the engine as obtained from a rotating part 5 thereof. The comparator 3 compares the difference between the desired signal and actual signal and outputs a differential signal which is fed to an electronic control system 6. The control system 6 outputs a corresponding control command signal which is applied to a driver circuit 7 by which a throttle valve 8 is adjustable. The position of the throttle valve 8 is fed back to the electronic control system 6.

The comparator 3 also outputs a signal depending on the difference between the desired signal and actual signal which is supplied to magnetically-controlled valves 9 arranged in the fuel supply lines 11 leading to injection nozzles 10 of the internal combustion engine. The magnetically controlled valves 9 are arranged to shut off the supply of fuel to the injection nozzles 10, each one of which is associated with a cylinder of the engine.

The operation of the device is as follows. By means of the accelerator pedal 2 the desired value transmitter 1 is adjusted to a pre-determined value which is proportional to a pre-determined engine speed orto a pre-determined travel velocity. An electrical desired signal corresponding -to this desired pre-determined engine speed is transmitted by the desired value transmitter 1 to the comparator 3.

By means of the speed transmitter 4, an actual value signal corresponding to the instantaneous engine speed or the instantaneous travel velocity, is transmitted to the comparator 3. The comparator 3 compares these two signals and outputs an electrical differential signal which is transmitted to the electronic control system 6.

If the desired signal is greater than the actual signal, the driver circuit 7 is controlled by the electronic control system 6 so that the throttle valve 8 opens to such an extent that the engine speed increases in order that the desired signal and actual signal become equal to one another.

Under these conditions, no electrical closure signal is transmitted by the comparator 3 to the magnetically-operated valves 9, so that the valves 9 keep the fuel lines 11 open.

If now the accelerator pedal 2 is released either partially or wholly from the position at which it was set to give the pre-determined value, or if for any other reason the actual value signal exceeds the desired value signal, for example due to the vehicle travelling downhill, the comparator 3 outputs a signal to the electronic control system 6 so as to control the driver circuit 7 to open the throttle valve 8 to a maximum opening position.

At the same time the comparator 3 outputs a closure signal to the magnetically controlled valve 9 in order to shut off the supply of fuel to the injection nozzles 1 0.

This condition continues untii the engine speed and therewith the actual signal drops to a value which corresponds to the desired signal. As soon as this happens i.e. the difference between the desired signal and the actual signal is zero, the driver circuit 7 is controlled by the electronic control system 6 so that the throttle valve 8 is opened to a position proportional to the desired signal.

In the case of the above described device for controlling the engine revolutions of an internal combustion engine it is especially advantageous if, below a pre-determined engine speed of for example be 800 R.P.M., no closure signal is supplied to the magnetically operated valves 9, so that fuel continues to be supplied to the injection nozzles 1 0. Determination of this speed zone or range is preferably made with the comparator 3. In this manner, when the travel speed is slow or when the engine is idling in stationary traffic, the engine runs-down, the engine does not stall or become incapable of being easily controlled in heavy traffic conditions.

In a modified form (not disclosed) the device includes a display (for example a lamp) which then responds when the speed variation per time unit is located below or above a pre-determined value.

As a result of the provision of this lamp, the driver receives an indication that on applying acceleration he is either in an excessively high gear and should change down to a lower gear, or is in an excessively low gear and should change up to a higher gear. Thus, in both cases optimum utilization of the fuel is achieved and this results in a reduction of the fuel consumption.

Claims

1. A device for controlling the engine revolutions of an internal combustion engine including: a desired value transmitter coupled to the accelerator pedal of the engine, said transmitter supplying a desired signal corresponding to the engine speed; a speed transmitter supplying an actual signal corresponding to the instantaneous engine revolutions; a comparator for comparing the desired signal with the actual signal; an electronic control circuit fed with the differential signal output from the comparator, said differential signal being the difference between the desired signal and the actual signal; a driver circuit controllable by the control circuit for adjusting the position of the throttle valve of the engine; and means also operable from the output from the comparator for shutting off the fuel supply to the engine; whereby in the event that the values of the desired signal and the actual signal are equal, the throttle valve is maintained in a position proportional to the desired signal; in the case where the desired signal is higher than the actual signal, the throttle valve is adjusted in the open direction; and in the event where the actual signal is higher than the desired signal, a closure signal is supplied by the comparator to shut off the fuel supply to the engine.

2. A device according to Claim 1, wherein in the event of the actual signal is higher than the desired signal, the throttle valve is adjusted in the opening direction.

3. A device according to Claim 2, wherein the throttle valve is adjusted to the maximum opening position.

4. A device according to any one of the preceding claims, wherein the signals are electrical analog signals.

5. A device according to any one of the preceding claims, wherein the fuel supply shutting off means is arranged in each fuel line extending to an injection nozzle of a cylinder of the engine.

6. A device according to Claim 5, wherein the fuel supply shutting off means is a magneticallyoperated valve.

7. A device according to Claim 6, wherein the magnetically-operated valve is energized in the case of a higher or identical desired signal relative to the actual signal, so as to maintain the supply of fuel to the injection nozzles of the engine.

8. A device for controlling the engine revolutions of an internal combustion engine constructed and arranged to operate substantially as herein described with reference to and as illustrated in the accompanying drawing.