GB2051406A

GB2051406A - Speed governor for diesel engines

Info

Publication number: GB2051406A
Application number: GB8014980A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-05-04
Filing date: 1980-05-06
Publication date: 1981-01-14
Also published as: DE3016219A1; AT374890B; GB2051406B; FR2455679A1; ATA335379A

Abstract

The invention provides a speed governor which adjusts the quantity of fuel supplied by the injection pump for all engine speeds and comprises a sleeve (2) axially displaceable in accordance with engine speed which includes a driver member (6) preloaded by an extension spring (7) urging it towards a stop (8) on the sleeve (2). When engine speed drops below a pre-set idling speed the sleeve (2) moves in one direction and drives one end (14) of a cranked lever (10), pivotally connected to the throttle lever (12), so that control linkage (15, 19) of the injection pump increases fuel delivery. When engine speed rises above idling the sleeve (2) moves in the opposite direction and the linkage (15, 19) moves accordingly to reduce the quantity of fuel injected. The governor includes a cam plate (22) which is connected to the sleeve (2) by a driver (21) and which functions to control the fuel supply and thus the engine speed outside the idling range. This is achieved through a compensation lever (24) and a roller (26) mounted thereon which is applied to compensation (31) and maximum (30) speed profile of the cam (22) by a spring (28). In supercharged engines the compensation lever (24) may be adjusted by a pressure sensitive device (39) or a second cam plate (40) and lever (36) may be provided. <IMAGE>

Description

SPECIFICATION Speed governor for compression ignition engines This invention relates to a speed governor for compression ignition engines, particularly as applied to engines used in motor vehicles, of the kind comprising an output member movable in accordance with engine speed and which transmits adjusting movements through a lever system to a control rod on the fuel injection pump to regulate fuel delivery from the injection pump in accordance with the engine speed.

Compression ignition engines having fuel injection systems, particularly as applied to motor vehicles, require a speed governor which maintains at least the idling and maximum speeds at predetermined limit values.

These governors influence the quantity of fuel injected only in the idling speed range between the lowest speed and the maximum idling speed and in the range between a nominal maximum governed speed and an even higher no-load speed. Throughout the rest of the total speed range the speed governor is totally ineffective and injection pump adjustment is made directly through the accelerator pedal as the means of controlling fuel supply. In other words, the vehicle driver is free to choose the quantity of fuel injected, and thus engine torque, to suit prevailing driving and road conditions.

A modern compression ignition engine requires, in addition to engine speed regulation in the upper and lower speed ranges, a device which controls the amount of fuel injected under full-load at every speed. Since it is no longer possible, in view of stringent exhaustgas emission regulations in force in some countries, at least partially to influence the fuel delivery characteristic by hydraulic means, a way must be found of applying positive and negative, that is plus and minus corrections of the quantity of fuel injected over the full engine speed range. Frequently certain provisions aimed at reducing exhaust gas emission which are customarily applied to the fuel injection system actually tend to aggravate the problem of compensation which is extremely hard to control, particularly with turbo-charged engines.

Speed governors are conceivable in which throughout the speed range any necessary adjustment of fuel delivery could be afforded by a measuring device provided specifically for compensation. Such a measuring device would then effect, in known manner, any compensation desired, for example by means of a separate slide valve control system. However, the numerous separate parts needed for this purpose inevitably add to the weight, size and cost of the speed governor.

It is the aim of the present invention to provide an idling to maximum speed governor which not only governs idling and maximum speeds but throughout the entire speed range enables the quantity of fuel injected to be adapted to the engine speed in a very simple manner.

This invention consists in a speed governor for compression ignition engines of the kind comprising an output member movable in accordance with engine speed and which transmits adjusting movements through a lever system to a control rod on the injection pump to regulate fuel delivery from the injector pump, wherein control means is provided for regulating the fuel delivery quantity over the whole speed range of the engine, said control means comprising an idler mechanism and a cam device co-operable with an engine speed adjusting lever of the lever system, the idler mechanism controlling the delivery quantity in the idling speed range and the cam device controlling the delivery quantity at higher than idling speds, and the arrangement being such that in operation when the idler mechanism is operative the cam device is inoperative and when the cam device is operative the idler mechanism is inoperative.

The invention also comprises a speed governor for compression ignition engines of the kind comprising a governor sleeve which is axially displacable in accordance with engine speed and which, jointly with an adjusting lever which is adjustable to the desired speed of engine rotation, adjusts a control lever, the control lever being operative by means of a control rod connected to the regulating sleeve of a fuel injection pump, together with a cam plate pivotally mounted on the governor housing and co-acting with slide means, to affect adjustments of the control rod in accordance with engine speed; in which the governor sleeve is connected to a driver member movable relative to the sleeve which is pre-loaded by an extension spring urging it towards a stop on the sleeve and which in operation coacts with the control lever and with an adjustable fixed stop, the control lever being pivotally connected adjacent to one end of the adjusting lever, the governor further including drive means carried by the sleeve which serves to rotate the cam plate as the sleeve moves in accordance with engine speed, and a fuel supply compensation lever urged by spring means towards the cam plate and which has one of its ends pivotally mounted on the governor housing whilst its other end serves in one mode of operation to drive the control rod in a direction which effects a reduction in fuel delivery and in another mode serves as a stop for the control rod, the cam plate comprising a fuel supply compensation profile in addition to a maximum speed control profile for regulating fuel delivery from the injector pump.

In this last mentioned arrangement the reg ulation of idling speed, which is adjustable in known manner by means of an end stop for the adjusting lever, is obtained by means of the governor sleeve which is directly actuated by the revolution counter device. The control lever which adjusts the control rod for the control sleeve of the fuel injection pump is actuated by a driver member, movable relative to the governor sleeve, which is spring-loaded into engagment with an end stop on the governor sleeve. However, this applies only to the idling speed range. When engine speed rises above this range the adjustable end stop has the effect of disengaging the transmission of drive from the governor sleeve to the driver member. Upwards of this speed, which can be preset by means of the adjustable end stop, idling speed regulation and control has terminated.In the next following speed range the quantity of fuel injected is primarily controlled by means of the adjusting lever. The cam plate which is rotatably mounted on the governor housing and rotationally displaced in accordance with engine speed by means of a further driver member which is rigidly connected to the governor sleeve, is provided with a fuel delivery compensation profile, as well as with a maximum speed profile and by rotating the lever which is pivoted to the governor housing affords a simple and easy method of fuel delivery-compensation throughout the full speed range and/or limiting maximum speed of the engine.

In the case of supercharged engines the pivot point of one lever end may be slidably adjustable in accordance with boost pressure.

This affords a simple method of achieving engine-speed as well as boost-pressure-controlled compensation of the quantity of fuel injected in supercharged engines. To this end, according to a further development of this invention, a second cam plate may be provided which would be driven by the governor sleeve in the same manner as the first cam plate, a second lever, having one end pivoted on the governor housing, co-acting with said second cam plate in such a way that the other end of the lever provides an end stop for the control rod so that it limits the maximum quantity of fuel injected at every engine speed in accordance with the configuration of the cam plate. Thus the well known inaccuracies in regulating the delivery quantity according to variations in boost pressure under full load conditions are avoided or at least reduced.

According to a further improvement of this invention the end of the second lever which is pivotally mounted on the governor housing is adjustable in accordance with ambient atmospheric pressure thus preventing engine overheating or overspeeding of the turbo-charger.

An embodiment of the invention will now be more particularly described, by way of example, with reference to the accompanying schematic drawings in which: Figure 1 shows a speed governor according to this invention in simplified illustration, and Figures 2 and 3 illustrate schematically conventional methods of obtaining a speed-proportional control signal for the speed governor.

In Fig. la a sleeve 2 constituting an output member of the speed governor is slidably displacable in the axial direction by a specified distance s on variation of engine speed n. The function s(n), that is to say the extent of the axial displacement of the sleeve 2 for a given variation of engine speed n will depend on the characteristic of the revolution counter device provided in a given case.

Fig. 2 illustrates the conventional method of providing a centrifugal force measuring device 1, driven mechanically by the engine, and using this to displace a sleeve 2 in the axial direction in relation with engine speed.

With increasing engine speed n the axial travel s of the sleeve 2 is controlled in accordance with the function s(n) which is determined by the design of the centrifugal force measuring device 1.

Another conventional method of controlling the sleeve 2 is illustrated in Fig. 3. An hydraulic slave unit 5 is actuated through a spool valve 4 by a revolution counter device 3 in such a way that the sleeve 2 is displaced in relation to engine speed. The measuring device 3 may also be a centrifugal device or any other suitable servo-unit, for example, a lifting magnet. In all these examples of arrangements for converting engine speed n into axial travel sof sleeve 2 the function s(n) may be arbitrarily chosen in accordance with requirements.

With further reference to Fig. 1, housed within the sleeve 2 which is axially displacable in accordance with engine speed there is a driver member 6, movable relative to the sleeve 2, which is pre-loaded by an extension spring 7 urging it towards an end stop 8 on the sleeve. Regulation of engine idling speed which is set by means of an adjustable end stop 1 3 for an adjusting lever 1 2 is obtained in the following way. When engine speed drops below the pre-set idling speed the sleeve 2 travels to the left, as viewed in Fig.

1, carrying with it the driver member 6 which is held against the end stop 8 by the spring 7. In the case of a vehicle engine the adjusting lever 1 2 is the accelerator pedal.

The driver member 6 has a recess 6' formed therein in which the spherical end 14 on one arm of a two-armed cranked control lever 10 is a working fit. The control lever 10 is pivotally mounted adjacent to the end 11 of the adjusting lever 1 2. Thus, since during idling of the engine the adjusting lever 1 2 abuts the end stop 13, the bearing in the end 11 of the adjusting lever 1 2 represents a fixed point for the control lever 10 so that when the engine speed falls below the required idler speed the end 1 4 of the control lever 10 is displaced to the left, as seen in Fig. 1, by the sleeve 2 and the control lever 10 rotates about point 11 in the direction of arrow 32.A driver pin 1 7 on the control lever 10 is slidable in an upper eye 1 6 of an intermediate rod 1 5 and together they constitute a lost motion linkage. The intermediate rod 15, together with the control rod 1 9 of an injection pump, not shown, which control rod 1 9 is connected to a driver pin 1 8 rigidly secured on the end of a hinge bar 18' on the intermedate rod 1 5 move in unison. When engine speed falls below the required idler speed the rod 1 5 is driven in the direction of increased pump delivery that is to say in the direction indicated by a + sign.

In the opposite case, that is to say when engine speed rises above the idling speed which has been preset by means of the end stop 1 3 on the adjusting lever 12, the sleeve 2 travels to the right, as viewed in Fig. 1, which, by virtue of the previously described connections now causes the control lever 10 to pivot about point 11 in the arrow direction 33 and the control rod 1 9 to be driven in the direction of decreasing pump delivery indicated by the - sign thereby reducing the fuel delivery quantity which had been set by the control sleeve on the injection pump, that is to say, reducing engine speed.

A compensation lever 24 which has one end thereof connected to a lower eye 29 of the intermediate rod 1 5 by means of the driver pin 34 constituting a further lost motion linkage cannot impede the above described regulating operations during idling because, as will be more specifically described below, the cam plate 22 which actuates the compensation lever 24 is not engaged at idling speed. The control lever 10, adjusting lever 12, intermediate rod 1 5 and the compensation lever 24 comprise a lever system for transmitting adjusting movements to the control rod 19.

The position of the end stop for the driver member 6 of sleeve 2 and thus the length of stroke 51 is adjustable by means of a set screw 9 so that when the engine speed which corresponds to the position of this end stop, and which must be higher than the maximum controlled idling speed, is reached the driver member 6, and therefore also the end 14 of control lever 10, are no longer driven by the sleeve 2. Consequently, as soon as the engine speed has been reached which was pre-set by means of set screw 9, the control lever 10 pivots about that end 1 4 thereof which is now fixed relative to the governor housing. This is the intermediate range of fuel supply regulation in which speed control is directly applied through the adjusting lever 1 2 according to the driver's selection.For increasing engine torque the adjusting lever 1 2 is displaced in the direction indicated by the "+" sign causing the control lever 10, pivoted to end 11 of lever 12, to turn about its end 14 in the direction of arrow 32 with the result that the quantity of fuel injected is increased as already decribed.

Throughout the entire speed range of the engine the movement of the sleeve 2 is transmitted by a driver member 21 rigidly connected therewith to the cam plate 22 which is pivotally mounted at point 23 on the governor housing. The driver member 21 comprises an arm having a headed portion which engages the sides of a continuous slot formed in the cam plate. The compensation lever 24, which has its other end pivotally mounted at a point 25 on the governor housing, carries a roller 26, mounted at a point 27 thereon and is urged towards the cam plate 22 by means of a tension spring 28 secured to the end 14' adjacent to the driver pin 1 7 on the control lever 10, this is effected by the interaction of the hinge bar 18', the lower eye 29 of the intermediate rod 15, the driver pin 1 8 and lever 24.By an appropriate choice of contour configuation for the cam plate in that region thereof which is engaged by roller 26 it is thus possible to control the fuel injection quantity curve correctly through the entire speed range of the engine.

In the illustrated example the cam plate 22 has two distinct contour regions. A compensation profile 31 which limits the quantity of fuel injected in the intermediate speed range starting from nominal idling speed up to a nominal maximum governor speed. Above this intermediate speed range an over-speed profile 30 on the other hand controls the required decrease of fuel delivery down to zero delivery, which is necessary to prevent overspeeding of the engine. If therefore, the cam plate 22 has been so far rotated by the speedcontrolled sleeve 2 that the starting point 32' of the maximum speed profile 30 co-acts with roller 26 on the lever 24, any further speed increase will rotate the cam plate 22 further in the direction of arrow 33' and the maximum speed profile 30 pushes the roller 26 with the lever 24 downwards. The lower eye 29 of the intermediate rod 1 5 is also forced downwardly by the driver pin 34 thus causing the control rod 1 9 to be displaced in direction "-", as already described, with the result that the injection delivery of the fuel pump is reduced.

If engine speed increases still further, for example in a vehicle travelling downhill, fuel delivery will be progressively reduced by the maximum speed profile 30 and eventually reach zero delivery.

From the foregoing decription it will be appreciated that the idling speed range is that delimited by the stops 1 3 and 9. The intermeiate speed range is that in which the fuel injection quantity is under the control of the cam profile 31 according to the point of contact of the periphery of the roller 26 with the profile 31. The overspeed range is that starting from the point 32' on the cam plate 22 and under the control of the cam profile 30 when the injection quantity is gradually reduced as the roller 26 moves towards the outer extremity of that profile.

Thus the engine regulating or governor characteristic can be readily influenced by the configuration of the cam plate 22, or rather of its contours in the region of the two profiles 30 and 31. For example, by an appropriate configuration of the maximum speed profile 30 it is possible to provide a shallow starting slope for the downward control curve in order to prevent a sudden drop in torque and/or to arrange for a steeper control curve with increasing engine speed in order to keep the maximum engine speed as low as possible In super-charged engines the pivot point 25 of compensation lever 24 is adjustable in relation to boost pressure by means of a suitable pressure sensing device 39, shown in dotted lines in Fig. 1. This applies an additional adjustment of the quantity of fuel delivered by the injection pump at every speed.

A further additional device provided in conjunction with the above-mentioned means for adjusting the quantity of fuel delivered in a super-charged engine is indicated in dotted lines in Fig. 1. This device comprises a second lever 36 having one of its ends 37 likewise pivotally mounted on the governor housing. The other end 38 of this lever 36 is arranged in the eye 29 as a lost motion linkage and acts as a movable stop for the end 34 of the lever 24 to limit the maximum possible quantity of fuel delivered in relation to engine speed in accordance with the contour configuration of a second cam plate 40, through a roller 41 mounted, on the second lever 36. In a similar manner to the modifying influence of boost pressure by providing a movable pivot point 25 it is also possible to use ambient atmospheric pressure at a point 37 applied by a suitable pressure sensing device.

Claims

1. A speed governor for compression ignition engines of the kind comprising an output member movable in accordance with engine speed and which transmits adjusting movements through a lever system to a control rod on the injection pump to regulate fuel delivery from the injection pump, wherein control means is provided for regulating the fuel delivery quantity over the whole speed range of the engine, said control means comprising an idler mechanism and a cam device cooperable with an engine speed adjusting lever of the lever system, the idle mechanism controlling the delivery quantity in the idling speed range and the cam device controlling the delivery quantity at higher than idling speeds, and the arrangement being such that in operation when the idler mechanism is operative the cam device is in-operative and when the cam device is operative the idler mechanism is in-operative.

2. A speed governor according to Claim 1 in which the output member is displaceable axially in accordance with engine speed.

3. A speed governor according to Claim 2 in which the output member is a regulating sleeve and the idler mechanism comprises the regulating sleeve and a drive member housed in and movable with respect to the sleeve and urged by spring means towards a stop on the sleeve, the drive member being drivingly connected with the lever system and adapted to co-act with an end stop which limits the idling speed control range.

4. A speed governor according to Claim 3 in which the lever system comprises a cranked control lever having one end thereof in driving connection with the drive member, the other end thereof connected to the control rod through a lost motion linkage and the cranked part of the control lever being pivotally connected to the adjusting lever.

5. A speed governor according to any one of the preceding Claims in which the cam device comprises a profiled body rotatably mounted on the governor housing and drivingly connected to the output member.

6. A speed governor according to Claim 5 in which the profiled cam body comprises a compensating profile for operation of the engine over an intermediate speed range and an over-speed profile effective above the intermediate speed range, each of said profiles being engageable by a roller mounted on a compenation lever of the lever system and connected to the control rod through a further lost motion linkage.

7. A speed governor according to any one of the preceding claims adapted for use with a turbo-supercharged engine in which the lever system comprises means for augmenting the injected fuel quantity according to boost pressure or ambient pressure.

8. A speed governor for compression ignition engines of the kind comprising a governor sleeve which is axially displaceable in accordance with engine speed and which, jointly with an adjusting lever which is adjustable to the desired speed of engine rotation, adjusts a control lever, the control lever being operative by means of a control rod connected to the regulating sleeve of a fuel injection pump, together with a cam plate pivotally mounted on the governor housing and coacting with slide means, to effect adjustments of the control rod in accordance with engine speed, in which the governor sleeve is connected to a driver member movable relative to the sleeve which is pre-loaded by an extension spring urging it towards a stop on the sleeve and which in operation co-acts with the control lever and with an adjustable fixed stop, the control lever being pivotally connected adjacent to one end of the adjusting lever, the governor further including drive means carried by the sleeve which serves to rotate the cam plate as the sleeve moves in accordance with engine speed, and a fuel supply compensation lever urged by spring means towards the cam plate and which has one of its ends pivotally mounted on the governor housing whilst its other end serves in one mode of operation to drive the control rod in a direction which effects a reduction in fuel delivery and in another mode serves as a stop for the control rod, the cam plate comprising a fuel supply compensation profile in addition to a maximum speed control profile for regulating fuel delivery from the injector pump.

9. A speed governor according to claim 8, for application to turbo-supercharged engines, in which the pivot point of the one end of the compensation lever is displaced in accordance with changes in boost pressure.

1 0. A speed governor according to claim 9, in which a second cam plate is provided which is driven by the sleeve in the same manner as the first cam plate and a second compensation lever having one end pivotally connected to the governor housing and which co-acts with said second cam plate in such a way that the other end of the said second compensation lever provides an end stop for the control rod thereby limiting maximum fuel delivery at any engine speed in accordance with the configuration of the cam plate.

11. A speed governor according to claim 10, in which that end of the second lever which is pivotally connected to the governor housing is adjustable in accordance with ambient atmospheric pressure.

1 2. A speed governor according to any one of Claims 7 to 10 in which the slide means for rotating the cam plate comprises a slot formed in the cam plate and the drive means carried by the sleeve comprises an arm having a headed portion which co-acts with the sides of the slot.

1 3. A speed governor for compression ignition engines substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.