GB1594461A

GB1594461A - Fuel injection pumping apparatus

Info

Publication number: GB1594461A
Application number: GB4811/77A
Authority: GB
Original assignee: CAV Ltd
Current assignee: CAV Ltd
Priority date: 1977-02-05
Filing date: 1977-02-05
Publication date: 1981-07-30
Also published as: ES466635A2; AR214663A1; FR2379700B2; IN149750B; IT7847906A0; JPS5397122A; AU3295478A; ZA78615B; AU518283B2; DE2804773A1; FR2379700A2

Description

(54) FUEL INJECTION PUMPING APPARATUS (71) We, CAV LIMITED, a British Company of Well Street, Birmingham, B19 2XF England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: This invention relates to fuel injection pumping apparatus for supplying fuel to an internal combustion engine and comprising an injection pump having an axially movable control rod for determining the amount of fuel delivered by the injection pump at each injection stroke, governor means comprising a first pivotal link mounted about a fixed axis, a second pivotal link pivotally connected at one end to the first link at a position removed from said fixed axis, a slot defined in said second link, pivot means located in said slot, operator adjustable means for adjusting the position of said pivot means within said slot, said second link being coupled at its other end to said control rod, a spring biased weight mechanism responsive to the speed of the associated engine, a servo-mechanism for effecting movement of said first link about said fixed axis, an operating member for the servo-mechanism, said operating member being coupled to said weight mechanism whereby movement of the weight mechanism with increasing speed, will effect through the servo-mechanism, movement of said first link in a direction to reduce the fuel supply to the engine and vice versa, said servo-mechanism acting to isolate the weight mechanism from forces acting on the control rod.

Such an apparatus as indicated above is described and claimed in the Specification of British Patent 1,469,119. There is also described in the above specification, means which is adjustable in accordance with the speed at which the apparatus is driven for varying the maximum amount of fuel which can be supplied by the injection pump.

As descfibed in the above mentioned specification the aforesaid means is coupled directly to the weight mechanism so as to be movable thereby. This means that the weight mechanism is subjected to any force which is required to move the aforesaid means or any force which is applied to the means. These forces can upset the operation of the weight mechanism and the object of the present invention is to provide an apparatus of the kind specified in an improved form.

According to the invention, an apparatus of the kind specified includes means adjustable in accordance with the speed at which the apparatus is driven for varying the maximum amount of fuel which can be delivered by the injection pump said means including a linkage which is coupled to and movable by said first link.

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 side elevation with parts removed for the sake of clarity looking in the direction of the arrow "B" of Figure 2, Figure 2 is a sectional end elevation, Figure 3 is a view in the direction of the arrow "A" of Figure 2 and again with parts removed for the sake of clarity, Figure 4 is a sectional view of a portion of the apparatus not seen in the remaining Figures and, Figure 5 is a scrap view of a portion of the apparatus looking in the direction of the arrow "A" of Figure 2.

With reference to the drawings, the apparatus comprises a pump housing (not shown), which houses a plurality of injection pumps collectively indicated at 10. The injection pumps are operated by means of cams which are mounted on a shaft 11 which extends into a housing 12 which in practice is secured to the pump housing. The housing 12 is provided with an end closure 13 and this together with the housing 12 defines a chamber 14 in which is located the governor mechanism. Also extending into the chamber is an axially movable fuel control rod 15, the axial setting of which determines the amount of fuel which is delivered by the injection pumps.

The shaft 11 carries a speed responsive means generally indicated at 16 and which includes a cup-shaped member 17 secured to the shaft, the cup-shaped member housing a plurality of governor weights 18. As the shaft rotates, the weights move outwardly and in so doing impart axial movement to a sleeve 19.

The sleeve 19 in turn imparts axial movement to a further sleeve 20 through the intermediary of a thrust bearing and formed in the sleeve 20 is a circumferential groove 21. Interposed between the sleeve 20 and a further sleeve 23 is a light coiled compression spring 22. The sleeve 23 engages a non-rotatable plate 24 which is accommodated within a recess which is defined in a hollow projection formed on the end closure. The plate 24 can move axially but it is restrained against angular movement.

Moreover, it is engaged by the end of a leaf spring 25. The extent of movement of the plate 24 by the leaf spring is determined by a circlip which is located within the wall of the recess and the force which can be imparted to the plate 24 by the leaf spring is determined by means of an adjustor 26 which in practice, is preset. It will be noted that the adjustor 26 can be adjusted from exterior of the housing. The opposite end of the leaf spring is engaged about a fixed pin 27.

In operation, as the speed at which the shaft rotator increases, the weights move outwardly and the sleeve 20 moves towards the sleeve 23 against the action of the spring 22.

The extent of movement however is limited by the abutment of the two sleeves. Such movement as described takes place at a relatively low speed and it will be understood that the spring 22 constitutes the governor spring when the engine is idling. Further movement of the sleeves is against the action of the spring 25 and the position of the sleeves depends upon the speed of rotation of the shaft.

Referring now to Figure 2 there is provided a rockable member 30 which is pivotally mounted about a pin 31 secured within the housing 12. The upper portion of the member 30 constitutes the aforesaid first link and it carries a pivot pin 32 about which is mounted one end of a link 33 forming the aforesaid second link. The other end of the link 33 as shown in Figure 1, is coupled to the control rod 15 by way of a lost motion connection 34. This comprises a pair of members 35, 36 which are movable axially in either direction relative to each other. Whichever the direction of axial movement, the movement is opposed by a coiled compression spring 37 which is preloaded. Therefore, until the preload of the spring 37 is overcome, movement of the member 36 will result in similar movement of the member 35. As described, the latter is coupled to the control rod 15.

The link 33 is provided intermediate its ends, with a longitudinal slot 38 this being clearly shown in Figure 1. slideable within the slot 38 is a block 39 which is carried by a pivotal link 40 the latter being coupled to an operator controlled lever 41. The lever 41 is secured to an angularly movable shaft 42 which extends to the exterior of the housing and which in use, is coupled to the throttle pedal of the vehicle of which the associated engine forms part. The block 39 constitutes an adjustable pivot for the link 33. When the shaft 42 is moved angularly the block 39 moves within the slot 38 but the path of movement of the block 39 is defined by a ramp surface 43 against which bears a roller 44 carried by the block 39.As the shaft 42 is moved angularly the block 39 moves parallel to the ramp surface and as previously mentioned, alters the pivot point of the link 33. It will be noted that the lever 41 is connected to the coiled tension spring 45 located within the housing and furthermore, exterior of the housing and as shown in Figure 3 the shaft 42 mounts an abutment member 46 defining a pair of limbs engageable with a pair of stops 47 respectively. These act to limit the extent of angular movement of the shaft 42. It must be emphasised that the spring 45 plays no part in the governing action.

The member 3(Y on lots nmb opposite to the limb constituting the aforesaid first link, carries a pivot pin 48 and pivotally mounted on this pin is a pivotal member 49. The member 49 carries on the opposite side of the pivot axis 31, a pin 50 which extends into an enlarged aperture 51 formed in the member 30 and the pin 50 has a head which defines a slipper 52 which is located in the circumferential groove 21. It will be noted that the pivot axis 31 is offset relative to the axis of rotation of the shaft 11 and that the axis of the pin 50 extends at right angles to the axis of rotation of the shaft. The pin 50 is provided to ensure that governing of the engine speed takes place even if a servo-mechanism to be described, should fail.When the sleeve 20 is moved by the weight mechanism, movement will be imparted to the slipper 52 and also the pivotal member 49. Such movement will occur until the pin 50 engages the surface of the aperture 51 and further movement of the pivotal member 49 will be transmitted to the member 30 which will move angularly about the axis 31.

Such angular movement will effect movement of the second link in the direction about the block 39, to reduce the amount of fuel supplied to the engine.

As has been mentioned a servo-mechanism is provided which effects angular movement of the member 30 about the axis 31. Any force which is required to move the member 30 is derived from the servo-mechanism so that the weight mechanism is not loaded by the aforesaid forces. As shown in Figure 3, the opposite ends of the member 30 are engageable by a pair of pistons 53, 54 which are housed within respective cylinders 55, 56. The diameter of the cylinder 55 is greater than that of the cylinder 56 and the axes of the two cylinders are substantially parallel to each other. The respective pistons bear against shaped portions on the member 30.The cylinder 56 is in constant communication with a source of liquid under pressure and the admission of this liquid under pressure to or the release of liquid from the cylinder 55 is controlled by a servo-valve generally indicated at 57 in Figure 4. The valve 57 comprises a fixed sleeve 58 in which is formed a bore 59. Opening into the bore are a pair of ports 60, 61 and the port 60 communicates with the source of fluid under pressure. The port 61 communicates with the cylinder 55 by way of a passage 62. Slidable within the bore is a valve element 63 having formed therein a longitudinally extending bore 64 open to the chamber 14.The valve element 63 is coupled by means of a link 65 to the pivotal member 49, the pivotal connection being intermediate the pins 48 and 50.

Formed in the periphery of the valve element 63 are a pair of grooves between which is defined a land 66. The axial width of the land 66 is sufficient to cover the port 61. One of the aforesaid- grooves is in constant communication with the port 60 whilst the other groove communicates with the passage 64 by way of a transverse drilling.

In operation, when the valve element is moved towards the left as seen in Figure 4, the port 61 is placed in communication with the groove which is in constant communication with the source of liquid under pressure. As a result this liquid under pressure is admitted to the cylinder 55 and the piston effects clockwise movement of the member 30 as seen in Figure 3. Conversely if the valve element is moved towards the right then the groove which is in constant communication with the chamber, is brought into register with the port 61 and the cylinder 55 is therefore placed in communication with the chamber thus reducing liquid pressure in cylinder 55. This allows the piston 54 to move the member 30 in the anti-clockwise direction as seen in Figure 3.

The movement of the valve element is controlled by the pivotal member 49 and movement of this member is effected by the sleeve 20. Thus when the sleeve 20 moves in either direction, movement of the member 49 will occur and this will effect movement of the valve element. However, since the member 49 is pivotally mounted upon the member 30 which is moved by the pistons, only limited movement of the member 30 will occur until the port 61 is covered by the land 66. It will be appreciated that the servo-mechanism described is a follow up servo-mechanism and the member 30 will pivot about the axis 31 by an amount determined by the movement of the slipper 52 by the sleeve 20.In the event that the supply of liquid under pressure fails then as has been described, the member 49 can be coupled to the member 30 by means of the pin 50 so that the weight mechanism can in an emergency, effect a reduction in the amount of fuel supplied to the engine sufficient to protect the engine against overspeeding.

In order to provide what is termed in the art "torque control" an adjustable maximum fuel stop is provided. The adjustment of the maximum fuel stop is effected indirectly by the weight mechanism as will be described.

The maximum fuel stop is constituted by the shaped surface of an angularly movable cam 70 with which is engageable a roller 71 mounted upon a pin extending laterally from a part 15a secured to the control rod 15. The cam 70 is angularly movable and for this purpose it is mounted about a pivot pin not shown which is journalled within a housing 72. This housing is mounted on an angularly adjustable plate 73 freely mounted about a shaft 74 extending across the chamber. The plate is in fact carried on a boss 75 and has a projecting portion which is engageable with an abutment 76 adjustable from exterior of the housing.The pivot which carries the cam 70 is secured to a lever 77 seen in Figure 5 and this in turn is coupled to one end of a link 78 which extends downwardly within the chamber and is coupled to a further lever 79 secured to one end of a boss 80 angularly movable about a pin 81. The pin 81 is secured within the housing and it is co-axial with the pivot 31. Also provided is a generally U shaped link member 82. One limb 83 of the link member is pivotally mounted about the pin 81 whilst the other limb is supported by the pins 32 and 48 carried by the rockable member 30.

The limb 83 carries a pin 84 and this is engaged with one end of a coiled torsion spring 85 which is located about the boss 80 The other end of the torsion spring is coupled to the boss. The arrangement is such that when the member 30 moves about the pivot 31, the link member is also moved and the movement of the link member is transmitted to the further lever 79 by way of the spring 85 which is pre-loaded. The relative angular position of the limb 83 and the further lever 79 is determined by an adjuster 87. Movement of the further lever will effect movement of the lever 77 through the intermediary of the link 78 and movement of the lever 77 will effect movement of the cam 70.In this manner the maximum amount of fuel which can be supplied by the apparatus is determined by the abutment of the roller with the cam and since the position of the cam is dependent upon the speed at which the apparatus is driven, so will the maximum fuel which can be supplied to the engine vary in accordance with the speed of the engine.

The apparatus also includes means whereby the supply of fuel to the engine can be stopped when so required. This is effected by a stop control which effects angular movement of the shaft 74. Coupled to the shaft 74 is a lever 86 engageable with the part 15a secured to the control rod and operable to move the control rod to the zero fuel position.

The link 34 is provided to minimise strain on the governor mechanism in the event that for example the stop control is operated whilst the throttle pedal is fully depressed. The spring 85 which constitutes a yieldable connection between the further lever 79 and the limb 83 is provided for the purpose of ensuring that when the control rod is in the excess fuel position in which position the roller 71 is clear of the cam surface of the cam 70, then when the engine speed increases, the movement of the governor linkage will not be prevented by abutment of the side wall of the cam 70 with the roller 71. The roller 71 can therefore be moved by the governor mechanism and when it is clear of the side wall of the cam, the cam can return to its correct position to thereafter limit the maximum amount of fuel which can be supplied to the engine.The supply of excess fuel to the engine can be obtained when the engine is at rest, by depression of the throttle pedal. The cam 70 is shaped so that in the rest position it does not constitute a maximum fuel stop and therefore the control rod can be moved to an excess fuel position for starting purposes.

WHAT WE CLAIM IS:- 1. A fuel injection pumping apparatus for supplying fuel to an internal combustion engine and comprising an injection pump having an axially movable control rod for determining the amount of fuel delivered by the injection pump at each injection stroke, governor means comprising a first pivotal link mounted about a fixed axis, a second pivotal link pivotally connected at one end to the first link at a position removed from said fixed axis, a slot defined in said second link, pivot means located in said slot, operator adjustable means for adjusting the position of said pivot mean' within said slot, said second link being coupled at its other end to said control rod, a spring biased weight mechanism responsive to the speed of the associated engine, a servomechanism for effecting movement of said first link about said fixed axis, an operating member for the servo-mechanism, said operating member being coupled to said weight mechanism whereby movement of the weight mechanism with increasing speed, will effect through the servo-mechanism movement of said first link in a direction to reduce the fuel supply to the engine and vice versa, said servomechanism acting to isolate the weight mechanism from forces acting on the control rod, and means adjustable in accordance with the speed at which the apparatus is driven for varying the maximum amount of fuel which can be delivered by the injection pump, said means including a linkage which is coupled to and movable by said first link.

2. An apparatus according to Claim 1 in which the means adjustable in accordance with the speed includes a cam having a surface engageable by roller means carried by the control rod, the position of said cam being adjustable through said linkage, by said servo-mechanism. 3. An apparatus according to Claim 2 in which said cam is angularly movable by said linkage, said cam being mdunted upon a shaft carried within a housing, and operator controlled movable means supporting said housing, whereby the surface of said cam can be moved out of the path of said roller when an excess of fuel is required to be supplied by the apparatus for starting purposes.

4. An apparatus according to Claim 3 including a pre-loaded spring in said linkage and through which the movement of the servomechanism is transmitted to said cam.

5. A fuel injection pumping apparatus for supplying fuel to an internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

86 engageable with the part 15a secured to the control rod and operable to move the control rod to the zero fuel position.

The link 34 is provided to minimise strain on the governor mechanism in the event that for example the stop control is operated whilst the throttle pedal is fully depressed. The spring 85 which constitutes a yieldable connection between the further lever 79 and the limb 83 is provided for the purpose of ensuring that when the control rod is in the excess fuel position in which position the roller 71 is clear of the cam surface of the cam 70, then when the engine speed increases, the movement of the governor linkage will not be prevented by abutment of the side wall of the cam 70 with the roller 71. The roller 71 can therefore be moved by the governor mechanism and when it is clear of the side wall of the cam, the cam can return to its correct position to thereafter limit the maximum amount of fuel which can be supplied to the engine.The supply of excess fuel to the engine can be obtained when the engine is at rest, by depression of the throttle pedal. The cam 70 is shaped so that in the rest position it does not constitute a maximum fuel stop and therefore the control rod can be moved to an excess fuel position for starting purposes.

WHAT WE CLAIM IS:- 1. A fuel injection pumping apparatus for supplying fuel to an internal combustion engine and comprising an injection pump having an axially movable control rod for determining the amount of fuel delivered by the injection pump at each injection stroke, governor means comprising a first pivotal link mounted about a fixed axis, a second pivotal link pivotally connected at one end to the first link at a position removed from said fixed axis, a slot defined in said second link, pivot means located in said slot, operator adjustable means for adjusting the position of said pivot mean' within said slot, said second link being coupled at its other end to said control rod, a spring biased weight mechanism responsive to the speed of the associated engine, a servomechanism for effecting movement of said first link about said fixed axis, an operating member for the servo-mechanism, said operating member being coupled to said weight mechanism whereby movement of the weight mechanism with increasing speed, will effect through the servo-mechanism movement of said first link in a direction to reduce the fuel supply to the engine and vice versa, said servomechanism acting to isolate the weight mechanism from forces acting on the control rod, and means adjustable in accordance with the speed at which the apparatus is driven for varying the maximum amount of fuel which can be delivered by the injection pump, said means including a linkage which is coupled to and movable by said first link.
2. An apparatus according to Claim 1 in which the means adjustable in accordance with the speed includes a cam having a surface engageable by roller means carried by the control rod, the position of said cam being adjustable through said linkage, by said servo-mechanism.
3. An apparatus according to Claim 2 in which said cam is angularly movable by said linkage, said cam being mdunted upon a shaft carried within a housing, and operator controlled movable means supporting said housing, whereby the surface of said cam can be moved out of the path of said roller when an excess of fuel is required to be supplied by the apparatus for starting purposes.
4. An apparatus according to Claim 3 including a pre-loaded spring in said linkage and through which the movement of the servomechanism is transmitted to said cam.
5. A fuel injection pumping apparatus for supplying fuel to an internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with reference to and as shown in the accompanying drawings.