GB2184486A - Accelerator mechanism for a motor vehicle i.c. engine - Google Patents

Abstract

The transmission between the accelerator pedal 1 and the power output control, e.g. an injection pump control rod 8, includes a preloaded spring 10 and means for providing a varying resistance to transmission movement on pedal depression. The varying resistance may be provided by a damper 12 which provides different degrees of damping dependant on its deflection or by a cam (14, Figure 1 or 17, Figure 6) which varies the degree of transmission movement transmitted to a damper or to a compression spring (13) dependant upon the stage of transmission movement. The force of the resistance spring (13) may be removed in specific engine speed ranges or dependant on accelerator pedal position. <IMAGE>

Description

SPECIFICATION Device for regulating an internal combustion engine in a motor vehicle The invention relates to a device for regulating a particularly air-compression type of internal com bus- tion engine in a motorvehicle comprising means of transmitting a regulating movement between an accelerator pedal and a power output stage, such as a control rod of an injection pump, a spring element which is fitted in the transmitting means and an elementwhich engages on a transmitting mean between the spring element and the power output stage and which exerts a resistance to counteract an actuating movement of the device in the full-load direction.

A device of this type is known because of its use in standard-type vehicles ofthe applicant company.

With this known device the movement of the power actuator is no longer directly determined by the movement ofthe accelerator pedal, but the regulating speed of the power actuator can, despite the arrangement ofthe resistance generating element, for example a damper, be so high that longitudinal oscillations are triggered in the moving motorvehicle as a result of this speed because, to ensure sufficient response back to the vehicle driver, the resili ence of the spring element should not fall below a specific value.

The longitudinal oscillations occur during driving because, when switching from propulsive to tractive operation even in the case of small adjustments of the power actuator in free acceleration which is made possible by backlash and elasticity in the drive train, the internal combustion engine reaches such high speeds that, when tractive operation commences, it is considerably delayed in such a manner that the resulting surge causes abrupt longitudinal oscillations in the motorvehicle which are unpleasantforthe passengers and harmful to the vehicle.

The problem underlying the invention is to developthe device in such a mannerthatthe long itudinal oscillations occasioned in this way are pre- vented or at least considerably reduced.

According to the invention, there is provided a device for regulating an internal combustion engine in a motor vehicle comprising a means oftransmitting a regulating movement between an accelerator pedal and a power output stage, such as a control rod of an injection pump, a spring element which is inserted in the transmitting means and an element which engages the transmitting means between the spring element and the power output stage and which exerts a resistance to counteract an actuating movement of the device in the full-load direction, wherein the pretensioned spring element can be overridden by operation ofthe accelerator pedal and a control device is provided on or in the element, or between the element and the transmitting means, the control device acting to vary, depending on time, the degree of resistance after the actuating movement is initiated.

In one aspect of the invention, the resistance reaches a maximum after a rise and then falls substantially, if necessary to zero, while in accordance with another aspect of the invention, the rise in resistance is preceded by a time period without any or with slight resistance.

In one embodiment ofthe invention, the control device is in the form of a cam; in an alternativeembodiment of the invention, the control device is in the form of a link member.

In a further embodiment of the invention, the elemend is afluid damper having at leastonethrottling port and having a damping powerwhich can be varied in a path-depending manner, particularly by a throttling cross-section which is variable in a pathdependent manner and/or by a path-dependent connection or disconnection of a throttling port.

According to anotherembodimentoftheinven- tion, the control device, when speed and/or loadcontrolled, can be rendered inoperative.

The regulating device constructed in accordance with the invention makes it possible, despite the relatively high resilience in the spring element, to keep the regulating movement of the power actuator so small fora limited time that the internal combustion engine is accelerated so little only a slight excess torque and speed relative to the vehicle. This causes the prevention of, or at least a considerable reduction of longitudinal oscillations during travel from the beginning.

As a result ofensuring that the resistance rises to a maximum and then falls back, if necessary to zero, not only is the required torque and speed adjustment ofthe internal combustion engine in the propulsive/ tractive transition area achieved, butalsothesubse- quentadaptation of the position ofthe poweractuator to the preset accelerator position is made possible within a very shorttime so that the delays occurring with the device according to the invention between the actuation of the accelerator pedal and the response ofthe internal combustion engine are kept within a restricted time limit.

By preceding the increase in resistance by a time delay which is free of resistance or has only a limited resistance, the response delay of the powerouput stage is further reduced, because any existing idling distances in the transmitting means and power output stage are covered rapidly.

Control devices which are in the forms of either a cam ora link member provide in a very simple and effective manner, for modulating the force generated by the element precisely within the required time variation.

It is possible to provide a different type of control device in which this device is integrated in the force generating element.

The possibility of rendering the speed and/or load controlled control device inoperative enables a resistance-free and thus rigid connection between the accelerator pedal and power actuator so that the delayed adjustment of the latter remains limited to operating conditions in which there is a dangeroflong- itudinal oscillations during travel.

Embodiments ofthe invention will now be described in more detail below byway of examples and with reference to the accompanying drawing; in which: Figure 1 shows a device comprising a damper as theforce-generating element and a linkmemberas the control device.

Figure2 shows a devicesimilarto that in Figure 1, with a spring acting as the force-generating element and a cam as the control element, Figure3showsa device in a governerofan injection pump with a damper acting astheforcegenerating element, Figure 4shows the damper of Figure 3 with a pathdependent control device, Figure5showsa diagramofthedependenceofthe regulating distance of the power output stage and regulating distance of the accelerator on time, and Figure 6shows a device corresponding to Figure 2 in which the control device can be rendered inoperative depending on speed.

As shown in Figures 1 to3,afloating lever 4 of a fuel injection pump 5, which is rigidly connected to an internal combustion engine (not shown in further detail), is actuated by an accelerator pedal 1 via rods 2,3. A return spring 6 engages on the floating lever 4.

As can be seen in Figure 3, a control lever7 is actuated via the floating lever4 and a control rod 8 acting as the power output stage is actuated via this control lever, the position of this control rod determining the quantity of fuel injected.

Fitted between the rods 2 and 3 (Figures 1 and 2) or betweenthefloating lever 4 and control lever7 (Figure 3) is a spring element 9 in which a pretensioned helical spring 10 is set in a housing 11. The housing 11 is rigidly connected to the transmitting means (rod 2 or floating lever4) at the accelerator pedal end and the spring 10 is rigidly connected to the transmitting means (rod 3 or control lever 7) on the end of the control rod 8.The spring 10, including its pretensioning, is so dimensioned that upon sudden operation ofthe accelerator pedal 1, it is overridden or compressed depending on a resistance which is exerted on the transmitting means between the spring element 9 and the control rod 8 and only in the following period oftime causes adjustment ofthe control rod 8 so that the position of the control rod 8 within this time is largely independent of the position ofthe accelerator 1.

On the other hand, when the accelerator pedal 1 is operated slowly, the spring element 9 acts as a rigid transmitting means.

The resistance mentioned above is generated by an element which can beintheform of a damper 12 (Figures 1,3 and 4) or in the form of a spring 13 (Figure 2). Between this element and thetransmitting means there is provided a control device which mod ifiestheforcegenerated by the element in such a mannerthatthe resistance exerted on thetransmitting means varieswith time.

In Figure 1 the control device is shown in the form of a link member 14which, on one side, is mounted on a joint 15 and, on the other side, is connected to the plunger 16 ofthe damper 12. The extended floating lever4 is guided in the link member 14. The connecting link is S-shaped so thatthree sections A,B,C are formed, of which the two outer sections A and C run essentially parallel to the pivoting movement of the floating lever 4, and the central section B extends obliquelythereto.Upon rapid movement of the ac- celerator pedal 1 the floating lever 4 is firstly adjusted rapidly against a slight resistance until it moves on to section Boftheconnecting link. Inthefollowing periodthefloating lever4 is adjusted even more slowly by the actuating force applied by the compressed spring 10 because the pivoting of the link member 14 and the associated movement ofthe plunger 16 generate a high damping force on the lever 4. In section Cthefloating iever4 is then adjusted rapidly again until the spring 10 reaches its pretensioned position and the position of the floating lever4 corresponds to the position of the accelerator 1.

In Figure 2 the control device is shown in the form of a cam 17 connected directly to the floating lever 4.

The cam path in turn consists of three sections A,B,C.

When the spring 13 acts on section A, the regulating movement of the floating lever4 is checked only slightly, and on section Cthe resistance generated by the spring 13 increases considerably, whereas in section Cthe spring 13 only generates a slight resistance or, if necessary, no resistance at all. In this embodimentthere is also a damper 18which acts on the transmitting means in the known manner.

In the embodiment shown in Figures 3 and 4the damper 12, which is connected directly to the control rod 8 by a bell-crank lever 19, is integrated in the governer housing 20 ofthe injection pump 5 and the con trol device in the damper 12. As shown in Figure 4, a pin 24 connected to the damper housing 23 extends intothethrottling port 21 of the damper plunger 22 when the latter is in its central position, and diminishesthethrottling cross-section considerably thus increasing the damping force, whereas with the throttling port 21 open the damping force is relatively small.

Figure 5 shows the regulating distances s of the accelerator pedal 1 and control rod 8 as a function of time t,with the continuous line corresponding to the embodiment according to the invention and the dotdash line corresponding to the embodiment without a control device. After a rapid adjustment of the accelerator pedal 1 the control rod 8 is adjusted rapidly within the periods a and c if the sectionsAand C of the connecting linkorcam path are operative orthe throttling port 21 is open, whereas the control rod 8 is adjusted only very slowly in period 6 if the sections B of the connecting link or cam path are operative or the cross-section of the throttling port 21 is reduced bythe pin 24. In this period of time b the internal combustion engine increases its speed only slowly and with a low torquf so that it can switch from propulsive to tractive operation with a slight excess of speed and surge of torque. The total period oftime until the position of the control rod 8 again corresponds to the position ofthe accelerator pedal 1, i.e., the periods a, band c combined, should be ofthe order of approximately half a second.

If there is no danger of longitudinal oscillations during travel, particularly in specific speed ranges of the internal combustion engine, a rigid connection between the accelerator 1 and control rod 8 is desirable. In this case, as shown in Figure 6, the spring 13 can be lifted from the cam 17 by a lifting device 25 depending on speed n so that the resistance generated bythe spring 13 ceases and the spring 10 can no longer be compressed excessively. Similar removal of resistance is also possible with the other embodiments of the invention, or also depending on the load, for example on the position ofthe accelerator pedal 1.

Claims (7)

1. A device for regulating an internal combustion engine in a motorvehicle comprising a means for transmitting a regulating movement between an accelerator pedal and a power output stage, such as a control rod of an injection pump, a spring element which is inserted in the transmitting means and an element which engages the transmitting means between the spring element and the power output stage and which exerts a resistance to counteract an actuating movement of the device in the full-load direction, wherein the pretensioned spring element can be overridden by operation of the accelerator pedal and a control device is provided on or in the element, or between the element and the transmitting means, the control device acting to vary, depending on time, the degree of resistance after the actuating movement is initiated.

2. A device according to claim 1, wherein the re sistance reaches a maximum after a rise and then falls substantially, if necessary to zero.

3. A device according to claim 2, wherein the rise in resistance is preceded by a time period without any or with slight resistance.

4. A device according to any one of claims 1 to 3, wherein the control is intheform of a cam ora link member.

5. A device according to any one of claims 1 to 3, wherein the element is a fluid damper having at least one throttling port and having a damping power which can be varied in a path-depending manner, particularly by a throttling cross-section which is variable in a path-dependent manner and/or by a pathdependent connection or disconnection of a throttling port.

6. A device according to any one of claims 1 to 5, wherein the control device, when speed and/or loadcontrolled, can be rendered inoperative.

7. A device for regulating an internal combustion engine in a motorvehicle,substantiallyashere- it before described and with reference to the accompanying drawings.