US3314406A - Liquid fuel pumping apparatus for internal combustion engines - Google Patents

Description

April 18, 1967 K. A. w. KEMP ETAL. 3,314,406

LIQUID FUEL PUMPING APPARATUS FOR INTERNAL COMBUSTION ENGINES Filed Jan. 7, 1965 5 Sheets-Sheet l 11:/ lf l S mmm N 4,

APrl 18, i967 K. A. w. KEMP ETAL. 3,314,406

LIQUID FUEL PUMPING APPARATUS FORINTERNAL COMBUSTION ENGINES Filed Jan. '7, 1965 5 Sheets-Sheet 2 April 1s, 1967 K. A. W. KEMP ETAL LIQUID FUEL PUMPING APPARATUS FOR INTERNAL COMBUSTION ENGINES Filed Jan. 7, 1965 3 Sheets-Sheet 5 United States Patent O 3,314,406 LIQUID FUEL PUMPING APPARATUS FOR INTERNAL COMBUSTION ENGINES Kenneth Albert Walters Kemp, Ealing, London, and Kenneth Frederick Gubb, Greenford, Middlesex, England, assignors to C.A.V. Limited, London, England Filed Jan. 7, 1965, Ser. No. 423,926 Claims priority, application Great Britain, lIan. 9, 1964,

10 Claims. (Cl. 12S-139;)

This invention relates to liquid fuel pumping apparatus of the kind used for supplying fuel to internal combustion engines and comprising a body, an injection pumpmounted in the body and arranged to be actuated in timed relationship with the engine with which the pump is associated and which, during a delivery stroke, delivers fuel to the engine, a feed pump for feeding fuel from a source to the injection pump at a pressure dependent upon the speed of lthe engine, and means for varying the quantity offuel fed by the feed pump to the injection pump.

The object of this invention is to provide such a pump in a simple and convenient form.

According to the invention a liquid fuel pumping apparatus of the kind specified comprises, in combination, a by-pass passage through which fuel in excess of the normal maximum can be fed from the feed pump to the injection pump, and a valve resiliently loaded towards a position to open said by-pass passage and movable against the resilient loading, to a position to close the by-pass passage, by the pressure of fuel delivered by the feed pump when the delivery pressure of the latter exceeds a predetermined value.

In the accompanying drawings:

FIGURE 1 is a sectional side elevation of one example of an apparatus in accordance with the invention,

FIGURE 2 is a sectional plan view on the line 2-2 of FIGURE 1,

FIGURE 3 is a sectional plan view on the line 3 3 of FIGURE l,

FIGURE 4 is a sectional plan view on the line 4-4 of FIGURE 1,

FIGURE 5 is a side elevation of part of the apparatus shown in FIGURE 1 with parts removed for the sake of clarity,

FIGURE 6 is a diagrammatic view showing the apparatus mounted on an engine and FIGURE 7 is a sectional view to an enlarged scale of part of the pump shown in FIGURE 1.

The drawings illustrate one example of an apparatus for supplying fuel to a six cylinder compression ignition engine indicated at 11 on FIGURE 6. Referring to the drawings there is provided a body part 12 in which is mounted a rotary cylindrical distributor member 13. The distributor lis arranged -to be driven in timed relationship with the engine by a drive shaft 14 which is at one end connected to the distributor and at its other end is adapted for connection to a rotary part of the engine.

In the distributor is formed a transverse bore 15 in which are mounted a pair of reciprocable plungers 16 which are arranged to be moved inwardly, as the distributor rotates, by rollers 16a which coact with a plurality of Vequi-angular spaced cam lobes 17 formed on the internal periphery of an angularly movable ring 18 surrounding the distributor. The transverse bore communicates with a longitudinal passage 19in the distributor and this communicates at one point with a radially disposed delivery passage 20 which is adapted to register in turn as the distributor rotates with a plurality of delivery ports 21. The aforesaid registration takes place at least during the whole time the plungers 16 are being moved inwardly by the cam lobes and the delivery ports communicate respectively rice with a plurality of injection nozzles 22 mounted so as to direct fuel into the combustion spaces of the engine respectively.

At another point the longitudinal passage 19 communicates with a plurality of equi-angularly spaced inlet passages 23 and these are arranged to communicate with a transfer port 24 defined in the body part during the time when the plungers -16 are free to move outwardly. The transfer port communicates with the inner end of a radially disposed cylinder 25 in the body part and in which is mounted a slidable shuttle 26 and the outward movement of the shuttle is limited by an adjustable stop 27. The outer end of the cylinder 25 is in communication with an annular groove 28 on the distributor, by way of a passage not shown, and extending from the groove are a plurality of equi-angularly spaced longitudinally extending grooves 29 each of which registers alternately and in turn with a drain port 3i) and a supply port 31. The drain port and supply port are angularly spaced from each other and the communication of the supply port 31 with a groove 29 is arranged to take place whilst an inlet passage 23 is in communication with the transfer port 24. Furthermore the communication of a groove 29 with the drain port 30 is arranged to take place during part of the time the transfer port 24 is out of communication with an inlet passage 23.

The supply port 31 communicates with the outlet 32 of a vane type feed pump 33 having an inlet 34 communicating with an inlet port 35 defined in a relief valve housing 36 secured to the body part. Within the housing is mounted a spring loaded relief valve 37 against which the pressure of fuel delivered by the feed pump acts. In use the valve moves to vary the effective size of spill orifice 38, the spill orifice being in communication with the inlet port 35 so that the pressure developed at the outlet of the feed pump is controlled and varies in a manner dependent upon the speed of rotation of the feed pump.

Also provided on the distributor is a circumferential groove 39 which communicates with the outlet 32 of the feed pump by way of an adjustable throttle member 40, the latter having a `groove 41 formed therein which registers with a port 42 defined in the body part and the -arrangement being that the angular setting of the throttle member determines the rate at which fuel can ow to the groove 39. Extending from the groove 39 are a plurality of equi-angularly spaced longitudinally extending grooves 40a, which lie inter-mediate the inlet passages 23 and which can communicate with the transfer port 24 as the distributor rotates.

The pump so far described operates as follows, when t-he transfer port 24 registers with one of the inlet passages 23 `the supply port 31 registers with one of the grooves 29 so that fuel is delivered to the outer end of the cylinder 25 and the shuttle 26 is moved inwardly causing fuel in the inner end ofthe cylinder to be displaced through an inlet passage, and the longitudinal passage to the bore 15, thereby causing the plungers 16 to be moved outwardly. During this time the delivery passage 2t) is out of register with a delivery port 21 but later as the distributor rotates the delivery passage communicates with a delivery port and at this time the plungers are moved inwardly by the cam lobes and fuel is delivered to an injection nozzle 22. At this time the transfer port 24 registers with one of the grooves 40a and one of the grooves 29 registers with the drain port 30 so ythat a quantity of fuel is fed to the inner end of t-he cylinder 25 and the shuttle 26 is moved outwardly by an amount depending upon the setting of the throttle member. As the distributor further rotates the cycle is repeated and fuel is supplied to the nozzles 22 in turn. The maximum amount of fuel which can be supplied to the engine is controlled by the setting of the stop 27 and this will occur when the load on the engine :is high. At other times thequantity of fuel supplied is determined by the setting of the throttle member which is controlled by a mechanical speed governor.

The speed governor includes a plurality of flyweights 41a which are supported in a cage 42 mounted on and rotatable with the drive shaft 14. As the weights move outwardly under t-he action of centrifugal force a collar 43 mounted about the shaft is moved in a direction towards the distributor. This movement is transmitted to one end of `a lever 44 which is pivotally mounted about a pivot 45 defined by a plate 416 secured to the body 12. The other end of the lever is pivotally connected to a rod 47 which is pivotally connected to a radius arm 48 extending from the throttle member. Furthermore said other end of the lever 44 -is connected to one end of a governor spring 49 the other end of which is connected to a manually operable throttle lever 50 and the arrangement is such that, 'for a given setting of the throttle lever 50, as the speed of the engine increases the setting of the throttle member will be varied to reduce the amount of fuel supplied to the engine until the force exerted by the spring 49 will be balanced by the centrifugal force acting on the weights. If the setting of the throttle lever 50 is altered then the throttle member will be moved accordingly until a fresh equilibrium is established.

For starting purposes it is necessary to provide an extra quantity of fuel and for this purpose there is provided in the body part fby a 4by-pass passage 5d which at one end communicates with a point downstream of the throttle member 40 and at its other end terminates in an excess fuel port 5,2 positioned so as to be exposed to one of the inlet passages at the same time as another of the inlet passages is in communication with the aforesaid transfer port 24. The flow of fuel through the by-pass passage is controlled by a spool 53 which -is slidably mounted in a chamber disposed substantially at right angles to the bypass passage. The spool is loaded by a spring 54 mounted in one end of the chamber towardsa position in which a groove S on the spool permits the iiow of fuel through the bypass passage. The other end of the chamber is in constant communication with the outlet olf the feed pump and the arrangement is such that when the engine is at rest the spool will be in the aforesaid position so f allowing fuel to dow directly from the throttle member to the transverse bore 15 as the engine is started, and thereby allowing the apparatus to supply an excess quantity of fuel. When the engine starts the pressure of fuel delivered by the feed pump .will increase until a point is reached when the force produced by the pressure of fuel acting on the end of the spool 53 remote from the spring 54 will be sufficient to move the spool to another position as shown in FIGURE l in which the by-pass port 52 is closed by a land on the spool. For retaining the spool in this position a latching device 55a is provided and this is shown to an enlarged scale in FIGURE 7.

The latching device comprises a hollow cylindrical latch body 56 which is engaged in a threaded bore formed in the body 12 and mounted within the latch body, in the manner of a piston, is a cylindrical member 57 which is provided with a blind bore'extending from its inner end and which is shaped at its outer end to define a push piece 58. Within the bore is slidably mounted a stepped cylindrical catch piece 60 which extends into the chamber containing the spool 53 at a position to engage within the lgroove 55 on the spool. The catch piece is spring loaded into engagement with the spool by a coiled spring 61 and the cylindrical member 57 is spring loaded outwardly and its outward movement is limited by the abutment of the push piece 58 with the end of a mushroom shaped head 62 which is -angularly movable in the latch body. The space defined between the inner end of the cylindrical member and the inner end of the bore accommodating the latch body is maintained full of fuel by way of a 4 restricted passage, defined by the screw threads which secure the latch body within the pump body and which communicates with an annular space defined by anon threaded portion of the latch body this latter` space being in communication with the feed pump inlet by a passage 63.

The arrangement is such 'that when the engine is at rest after having previously been in operation the latch will hold the spool in the position in fwhich the by-pass passage is closed; When au operator wants to start the engine he moves the head 62 by 'any convenient means to depress the push piece 58 quickly and the sudden rise in fuel pressure in the space surrounding the catch 60 acts on the inner end thereof and moves it against its spring to disengage the spool which then moves under'the action of its spring 54 to open the by-pass passage'. When the engine starts the spool moves as previously described and the catch piece re-engages therewitht As is usual with pumping apparatus of this kind the timing of injection of fuel to the engine can be adjusted in accordance with the speed of the engine and for this purpose the ring 13 is angularly movable .in the body part. The ring is connected by a peg 64 to a duid pressure operable piston 65 which is contained Within a tangentially disposed cylinder secured to the body part. The

vpiston is loaded by coil springs towards one end of the cylinder and fuel is supplied to the other end of the cylin` der by way of a passage 66 which is partly defined in a bolt serving to secure the cylinder to the body part and partly within the lbody part itself. The passage 66 contains a ball valve 67 which acts to prevent .the ring being moved angularly by the reaction of the rollers 16a with the cam lobes. Moreover fuel Ycan leak at a restricted rate between the piston and cylinder so that when the pressure at the feed pump outlet is fallin-g the piston can be moved by its spring to vary the timing of the injection of fuel. As an additional feature the spool 53 also controls the supply of fuel to the passage 66 this being arranged by a port 68 whichV opens into the chamber iu which thespool is mounted at a position so that when the spool is in a position to allow excess fuel to be supplied the port 68 will be closed. Thus until the engine has started fuel under pressure is not admitted to the cylinder containing the piston 65 so that the timing of injection of fuel during the starting sequence is retarded.

The latching device 55a incorporates the additional feature inrthat even if the push piece is held depressed the fluid pressure in the space surrounding the catch piece is moved inwardly by its spring. This feature together with the movement of the spool by the pressure of fuel supplied by the supply pump makes it quite impossible for an operator to make the apparatus supply excess fuel once the engine has started to run.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

1. A liquid fuel pumping apparatus comprising in combination a body part, an injection Vpump mounted in the body part and arranged to partake of alternate filling and delivery stro-kes,'a feed pump for feeding fuel to the injection pump during a filling stroke thereof at a pressure dependant upon the rate at which the apparatus is driven, means for controlling the quantity of fuel delivered to the injection pump during the filling stroke, a by-pass passage through which fuel in excess of the normal maximum quantity can be fed from the feed pump to the injection pump, a valve controlling said by-pass passage, resilient means loading said valve to a first position in which the by-.pass passage is open, said valve being exposed to the pressure of fuel delivered by said feed pump and arranged to move against the action of the resilient means when the pressure of fuel delivered by the feed pump exceeds a predetermined value, to a second position in which the by-pass passage is closed.

2. Apparatus as claimed in claim 1 including latch means for retaining the valve in said second position, and

manually operable means for releasing said latch means to allow the valve to move to said irst position when the pressure of fuel delivered by the feed pump is below said predetermined value.

3. Apparatus as claimed in claim 2 in which said latch means comprises a hollow latch body, a member slidably mounted within the latch body, resilient means urging the member in an outward direction, a bore extending from the inner end of said member, a catch piece slidably mounted within said bore, further resilient means urging said catch piece in a direction out of the bore, the exposed end of said catch piece bein-g arranged to engage with said vala/e to retain same in said second position, said manually operable means when operated, serving to move said member inwardly thereby to create a iiuid pressure which acts to move said catch piece inwardly and to permit the valve to move to said first position.

4. Apparatus as claimed in claim 3 in which the bore in the member is a blind bore, and there is provided passage means serving to place said blind end of the bore in communication with a source of liquid fuel, and restricted passage means serving to place the space at the end of the member in communication with the blind end of said bore whereby if the member is held depressed said fluid pressure will be dissipated through said restricted passage means.

5. Apparatus as claimed in claim 4 including timing means operable by the output pressure of the feed pump for varying the timing of said injection pump, and extra passage means through which said pressure is applied to said timing means, said valve also controlling said extra passage means.

6. Liquid fuel pumping apparatus for supplying fuel to a multi-cylinder internal combuston engine and cornprising in combination a body part, an injection pump mounted within the body part, a distributor rotatably mounted within the body p-art, the injection pump and distributor being arranged to be driven in timed relationship to the engine with which the apparatus is associated, passages in the distributor and cooperating ports in the body part for distributing fuel to the combustion spaces of the engine in turn, a shuttle mounted within a cylinder in the tbody part, a feed pump the output pressure of which varies in accordance with the speed at which the apparatus is driven, further passages in the distributor and body part whereby fuel can be fed from the feed pump to opposite ends of the cylinder containing the shuttle in turn and whereby fuel displaced from one end of the cylinder will be delivered to the injection pump, a throttle member for controlling the quantity of fuel delivered to said one end of the cylinder, a stop for limiting the movement of the shuttle so that the maximum amount of fuel which can be fed to the engine during the normal running thereof is limited, a bypass passage through which fuel in excess of the normal maximum quantity can be fed from the feed pump to the injection pump, a valve controlling said lby-pass passage, a resilient means loading said valve to a first position in which the by-pass passage is open, said valve being exposed to the pressure of fuel delivered by said feed pump and arranged to move against the action of the resilient means when the pressure of fuel delivered by the feed pump exceeds a predetermined value, to a second position in which the by-pass passage is closed.

7. Apparatus as claimed in claim 6 including latch means for retaining the valve in said second position, and manually operable means for releasing said latch means to allow the valve to move to said first position when the pressure of fuel delivered by the feed pump is below said predetermined value.

8. Apparatus as claimed in claim 7 in which said latch means comprises a hollow latch body, a member slidably mounted within the latch body, resilient means urging the member in an outward direction, a bore extending from the inner end of said member, a catch piece slidably mounted within said bore, further resilient means urging said catch piece in a direction out of the bore, the exposed end of said catch piece being arranged to engage with said valve to retain same in said second position, said manually operable means when operated, serving to move said member inwardly thereby to create a uid pressure which acts to move said catch piece inwardly and to permit the valfve to move to said iirst position.

9. Apparatus as claimed in claim 8 in which the bore in the member is a -blind bore, and there is provided passage means placing said blind end of the bore in communication with a source of liquid fuel, and restricted passage means serving to place the space at the end of the member in communication with the blind end of said bore whereby if the member is held depressed said fluid pressure will be dissipated through said restricted passage means.

10. Apparatus as claimed in claim 9 including timing means operable by the output pressure of the feed pump for varying the timing of said injection pump, and extra passage means through which said pressure is applied to said timing means, said valve also controlling said extra passage means.

References Cited by the Examiner UNITED STATES PATENTS 5/11958 Evans 103-37 3/196'2 Hutcheon 123--139

Claims (1)

1. A LIQUID FUEL PUMPING APPARATUS COMPRISING IN COMBINATION A BODY PART, AN INJECTION PUMP MOUNTED IN THE BODY PART AND ARRANGED TO PARTAKE OF ALTERNATE FILLING AND DELIVERY STROKES, A FEED PUMP FOR FEEDING FUEL TO THE INJECTION PUMP DURING A FILLING STROKE THEREOF AT A PRESSURE DEPENDANT UPON THE RATE AT WHICH THE APPARATUS IS DRIVEN, MEANS FOR CONTROLLING THE QUANTITY OF FUEL DELIVERED TO THE INJECTION PUMP DURING THE FILLING STROKE, A BY-PASS PASSAGE THROUGH WHICH FUEL IN EXCESS OF THE NORMAL MAXIMUM QUANTITY CAN BE FED FROM THE FEED PUMP TO THE INJECTION PUMP, A VALVE CONTROLLING SAID BY-PASS PASSAGE, RESILIENT MEANS LOADING SAID VALVE TO A FIRST POSI-

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