GB2063513A

GB2063513A - A speed governor with fuel injection pumping apparatus

Info

Publication number: GB2063513A
Application number: GB8034476A
Authority: GB
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1979-11-13
Filing date: 1980-10-27
Publication date: 1981-06-03
Also published as: GB2063513B

Abstract

A pump control member 12 as axially movable to determine the fuel quantity supplied. The control member 12 must be positioned for starting and should be maintained at a predetermined position until a servo mechanism 28 is operative. A first spring 47 acts on the control member to it in a fuel reducing direction and a second spring 50 in the opposite direction. A stop surface 49 is engageable by a collar 48 and a head 46 on the control member is urged towards the collar 48 by the first spring. Spring 50 exerts the greater force so that in the absence of any force exerted from the speed responsive means the collar will be held against the stop. A servo valve 37 in a piston 33 and cylinder 29 is operated by a centrifugal speed sensor 15 via a bell crank 24. The piston receives oil pressure via a port 31 and moves a bell crank 36, 26 in accordance with the valve position. The effect of a manually adjusted loading spring 19 is varied by movement of a roller 20 via a lever 22. <IMAGE>

Description

SPECIFICATION Fuel injection pumping apparatus This invention relates to fuel injection pumping apparatus for supplying fuel to an internal combustion engine and of the type comprising an injection pump including a control member movable to vary the amount of fuel supplied by the apparatus, a governor mechanism including a speed responsive device which in use is responsive to the speed of the associated engine and which effects movement of an output member against the action of resilient means the force exerted by which can be varied by an operator adjustable member, and a servo mechanism for moving the control member, said servo mechanism including an inpute member which is connected to said output member.

In known forms of such apparaus the fluid under pressure for operating the servo mechanism is derived from the lubrication system of the associated engine. As a result there can be a short period after the engine has started during which the servo mechanism is inoperative due to the lack of oil under pressure. It has therefore been the practice to provide a lost motion connection between the aforesaid output member and the control member to try to provide some sort of governing action during this period. The benefit derived from the use of a servo mechanism is that the speed responsive device which for example may include centrifugal weights, does not have to develop any appreciable force and hence it can be made small. Because it is small and because of the lost motion connection its ability to govern the engine is poor although it can act to limit the maximum speed of the engine.The effect is such that during the period when the servo mechanism is inoperative the engine speed can fluctuate over a wide range.

The object of the present invention is to provide an apparatus of the kind specified in a simple and convenient form.

According to the invention an apparatus of the kind specified comprises a clamping means operable when the servo mechanism is inoperative, to move and retain the control member in a predetermined position, said clamping means including resilient means the force exerted by which can be overcome by the servo mechanism and also by said speed responsive means in the event that the engine speed exceeds a predetermined value.

An example of an apparatus in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a diagrammatic sectional side elevation of a portion of the apparatus, Figures 2, 3 and 4 show portions of the apparatus not seen in Figure 1 in different settings, and Figures 5, 6 and 7 show a modification of the portion of the apparatus seen in Figure 2 again in different settings.

Referring to Figure 1 of the drawings the apparatus includes a governor casing 10 which in practice, is bolted to the casting of a fuel injection pump housing part of which is indicated at 11.

The fuel injection pump is provided with a control member 12 in the form of an axially movable member and the injection pump also includes a drive shaft 13 which extends into the governor casing. A cam 14 is shown on the drive shaft, the cam operafing one of a plurality of injection pumps which are located in the housing.

The portion of the shaft within the governor casing mounts a speed responsive device generally indicated at 1 5 and this in the particular example, comprises a plurality of weights 1 6 which are mounted in a cage 1 7 driven by the shaft. The weights engage a flange formed on an axially movable sleeve 18 on the shaft 13 and engaging with a further flange on the sleeve is a leaf spring 1 9 the other end of which is secured within the governor casing 10. The spring is engageable by a roller 20 the position of which on a ramp surface 21, is determined by an operator adjustable lever 22. When the lever is moved in a clockwise direction as shown in Figure 1 , the force exerted by the spring 1 9 on the sleeve 1 8 is increased.The sleeve mounts an output member 23 and this is coupled to one arm of a bellcrank lever 24 mounted about a pivot 25. Also mounted about the pivot 25 is a lever 26 which has a projection which is held in engagement by a coiled tension spring 27, with the end of the control member 12.

A servo mechanism generally indicated at 28 is provided and this comprises a stepped cylinder 29 the narrower end of which communicates with a drain by way of a passage 30. The wider end of the cylinder communicates by way of a passage 31, with the output of the oil pump 32 of the engine with which the apparatus is associated.

Slidable within the wider end of the cylinder is a piston 33. Integrally formed with the piston are cylindrical guide portions one of which is slidable within the narrower portion of the cylinder and the other of which extends through an aperture formed in the end wall defining the wider portion of the cylinder. This guide portion which is referenced 35, is coupled to an arm 36 integrally formed with the lever 26.

Formed within the piston and guide portions is a bore 34 and in this bore is located a servo valve 37. The servo valve has a head 38 movable towards and away from the end of the guide portion which is slidable within the narrower portion of the cylinder so as to form an adjustable valve. The servo valve member 37 is also provided with a land 39 and it is coupled to the other arm of the bell-crank lever 24.

The guide portion which extends through the aperture in the end wall of the cylinder has a larger diameter than the guide portion which is slidable within the narrower portion of the cylinder. Two annular spaces are defined on the opposite sides of the piston 33 and the one space is in constant communication by way of the port 31, with the outlet of the pump 32. The other space can be brought into communication with the outlet of the pump by way of ports 40 the flow through which is controlled by the land 39. Moreover, the other annular space communicates with the bore 34 by way of ports 41. In operation, if the valve member is moved downwardly as shown in Figure 1, the head 38 of the valve member moves towards the end of the guide and the ports 40 will be opened by the land to allow oil to flow into the other annular space.The pressure in the other annular space will increase and since the surface of the piston exposed to the pressure in the other annular space has a larger area than the other surface, the piston will move downwardly and it will assume a new equilibrium position.

Conversely as the valve member is moved upwardly the head 38 moves away from the guide and the ports 40 are closed by the land to reduce the pressure in the other annular space so that the pressure acting on the lower surface of the piston will effect upward movement thereof. Since the piston is connected to the lever 26, movement thereof will effect movement of the control member 12 and if the piston moves upwardly, the control member will be moved to reduce the amount of fuel supplied by the pump to the associated engine. Considering the mechanism as a whole therefore, as the weights 16 move outwardly, the sleeve 18 will move towards the right and the valve member will be moved upwardly. The piston will follow such movement and the quantity of fuel supplied to the engine will be reduced.

The lever 26 carries a pin 42 which can be engaged by a portion of the bellcrank lever 24 in the event that the servo fails to operate and the engine speed exceeds a predetermined value. In this case movement of the control member 12 towards the minimum fuel position will occur. It will be noted that the control member 12 carries a projection 43 which is engageable with a stop 44 carried on the casing. The stop 44 constitutes the maximum fuel stop.

When it is required to start the engine it is of course necessary that the pump should supply fuel and therefore for starting purposes the control member 12 cannot be in the minimum or zero fuel position. Clamping means which will now be explained, is therefore provided which in the absence of any forces from the speed responsive mechanism i.e. the weights 1 6 or the servo mechanism, moves the control member 12 to a predetermined position at which position sufficient fuel will be provided by the pump to enable the associated engine to be started. It should be pointed out that this type of pump is associated with an engine which does not require an excess of fuel for starting purposes.

The clamping means is seen generally at 45 in Figures 2, 3 and 4. It should be remembered that these figures are diagrammatic and if necessary, the clamping means can be housed within the governor housing. The control member 12 extends into a bore and is provided with a head 46 against which bears a coiled compression spring 47. The spring 47 urges the control member to the zero fuel position. The control member also has slidably mounted thereon a collar 48 and the collar 48 is urged into engagement with a step 49 defined in the bore by means of a coiled compression spring 50.In the rest position of the associated engine the spring 50 is sufficiently strong to maintain the collar in engagement with the step, against the action of the spring 47 and the control member 12 is maintained in a predetermined position which is nevertheless sufficient to ensure a supply of fuel to the associated engine for starting purposes. Neither of the springs 47, 50 is sufficiently strong to oppose the action of the servo mechanism and in the event that the servo mechanism 28 calls for more fuel, the control member 1 2 is moved against the action of the spring 47 towards the maximum fuel position. The position of the various components of the clamping means in this situation is seen in Figure 3.If on the other hand the servo mechanism or the weights, move the control rherriber 12 stop to the zer fuei positin, the spring~47 assists such movement and the force exerted by the spring 50 is overcome. This situation is shown in Figure 4. When the engine is stopped therefore the control member 12 will be moved to the position shown in Figure 2 by the action of one or the other of the springs 47, 50.

In order to stop the engine the control member 12 must be positively moved to the zero fuel position and this can be achieved using a manually operable stop lever.

Conveniently the predetermined position to which the member 12 is moved by the action of the clamping means is a low fuel position which will allow the engine to operate at just below its normal idling speed. The predetermined position may however be such as to allow the engine to operate at about or slightly above its normal idling speed.

The apparatus described does not permit the supply of excess fuel to the associated engine for starting purposes. The supply of such an excess is necessary for the starting of a large number of engines since the provision of engine air intake manifold heaters is less common.

The modifications illustrated in Figures 5, 6 and 7 does enable an excess of fuel to be supplied.

With reference to these figures the control member is again indicated at 12 but in this example it is moved to the right to decrease the fuel flow to the engine. The control member passes into a sleeve 51 which has formed in it a pair of slots 52 within which is mounted a pin 53 extending through the control member. The pin is engaged by a spring abutment 54 between which and a flange at the left hand end of the sleeve is a coiled compression spring 55.

Engageable with the end of the control member 12 is the head of a pin 56 which extends through an aperture at the remote end of the sleeve. The pin is biassed towards the control member by a coiled compression spring 57 and the extent of such movement is limited by an adjustable abutment 58 carried by the rod and engageable with the end wall of the sleeve. The spring 57 corresponds to the spring 50 of the first example whilst the spring 55 corresponds to the spring 47 of the first example.

The sleeve 51 is provided with a flange 59 which is engaged by a coiled compression spring 60 which is positioned between the flanges 59 and an abutment plate 61 the thickness of which can be selected. The extent of compression of the spring 60 is determined by a tubular member 62 engaging the plate 61 and engageable by the flange 59.

On the other side the flange 59 is engaged by a further coiled compression spring 63 the remote end of which engages a step defined in the internal wall of a further tubular member 64 which is fixed within the housing as also is the aforesaid plate 61. The extent of compression of the spring 63 is limited by contact of the flange with the end of the tubular member 64. The spring 63 is a special spring which when the spring is hot functions as a normal coiled compression spring but when cold it of its own volition, becomes close coiled as seen in Figure 6. One example of such a spring is known as a "Delta Memory Spring." In operation, when the engine is hot but is not in operation so that the servo is inoperative, the control member assumes the position shown in Figure 5.The flange 59 is urged by the spring 63 into engagement with the tubular member 62 and the control member 12 assumes a position determined by the springs 55, 57. This may be the predetermined position described with reference to the previous example, i.e. a low fuel position such that the engine when started operates at around the normal idling speed. If the engine is cold then with the engine at rest the control member 12 assumes the position shown in Figure 6 with the spring 63 in a collapsed state.

In this position the maximum fuel stop 44 is engaged by the projection 43 and the spring 57 is compressed so that the abutment 58 is out of contact with the sleeve 51. If excess fuel is required then the projection 43 is moved out of contact with the stop 44. This can be achieved by lateral movement of part of the projection 43. The control member 12 then moves under the action of the spring 57 to the position shown in Figure 7.

In this position the abutment 58 once again engages the sleeve 51 and excess fuel will be supplied to the engine when it is cranked for starting purposes.

When the engine starts since it is being supplied with excess fuel it will accelerate until the speed responsive device and/or the servo mechanism effects movement of the control member and limits the engine speed. As soon as the control member is moved away from the excess fuel position by the speed responsive device and/or the servo mechanism, the part of the projection 43 moves into a position to engage the maximum fuel stop so that thereafter no more than the normal maximum quantity of fuel as determined by the stop 44 can be supplied.

As the engine runs the spring 63 is heated and expands to urge the flange 59 into contact with the tubular member 62 so that in the event that the servo mechanism fails the control member will be returned to the position shown in Figure 5.

In practice it is found that the delay in the supply of oil under pressure to the servo mechanism is at its greatest when the engine is hot and that when the engine is cold there is substantially no delay and that the servo mechanism effects movement of the control rod before the engine speed reaches such a value that the engine speed responsive means starts to move the control member. It is nevertheless capable of doing this if for some reason the oil pressure does not rise to cause operation of the servo mechanism.

Claims

1. A fuel injection pumping apparatus for supplying fuel to an internal combustion engine and of the kind comprising an injection pump including a control member movable to vary the amount of fuel supplied by the apparatus, a governor mechanism including a speed responsive device which in use is responsive to the speed of the associated engine and which effects movement of an output member against the action of resilient means the force exerted by which can be varied by an operator adjustable member, a servo mechanism for moving the control member, said servo mechanism including an input member which is connected to said output member, clamping means operable when the servo mechanism is inoperative, to move and retain the control member in a predetermined position, said clamping means including resilient means the force exerted by which can be overcome by the servo mechanism and also by said speed responsive means in the event that the engine speed exceeds a predetermined value.

2. An apparatus according to claim 1 in which said resilient means includes a first spring acting on the control member in a direction to move the control member to a minimum fuel position, a second spring, a member biassed by said second spring in a direction opposite to that in which the control member is biassed by said first spring, a stop surface towards which said member is urged by said second spring and means on said control member for engagement with said member, said second spring in the absence of any force developed by said speed responsive means and/or said servo mechanism acting to maintain said member in contact with said stop surface and acting to position said control member in said predetermined position.

3. An apparatus according to claim 2 in which said member comprises a coffer mounted about and slideable relative to the control member.

4. An apparatus according to claim 1 including a sleeve mounted about and slidable relative to the control member, temperature responsive means for determining the axial position of said sleeve, said temperature responsive means when the associated engine is cold causing said sleeve to occupy a first position which is removed from a second position which it adopts when the engine is cold, in the direction of movement of the control member to increase the supply of fuel delivered by the injection pump, a first spring acting between said sleeve and the control member and acting to urge the control member in a direction to decrease the amount of fuel supplied by the injection pump, a second spring acting between the sleeve and the control member in opposition to the first spring and means for limiting the extension of said second spring.

5. An apparatus according to claim 4 in which said sleeve is provided with a longitudinal slot, a pin carried by said control member and slidable in said slot and spring abutment against which bears said first spring to urge the abutment against said pin.

6. An apparatus according to claim 4 or claim 5 in which said temperature responsive means comprises a temperature responsive spring, said temperature responsive spring acting against one side of a flange on said sleeve and a coiled compression spring acting against the other side of said flange.

7. An apparatus as claimed in claims 4, 5 or 6 including a stop engageable witha projection carried by the control member to determine the maximum amount of fuel which can be supplied by the apparatus, said stop and projection being relatively movable to permit the control member when the associated engine is cold, to move to a position in which an excess of fuel is supplied for starting purposes.

8. A liquid fuel injection pumping apparatus for supplying fuel to an internal combustion engine and comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figure 1 as modified by Figures 2, 3 and 4 of the accompanying drawings.

9. A liquid fuel injection pumping apparatus for supplying fuel to an internal combustion engine and comprising the combination and arrangement of parts substantially as hereinbefoce described with reference to Figure 1 as modified by Figures 5, 6 and 7 of the accompanying drawings.