US3289590A

US3289590A - Liquid fuel pumping apparatus for internal combustion engines

Info

Publication number: US3289590A
Application number: US396076A
Authority: US
Inventors: Hutcheon Keith Finer
Original assignee: CAV Ltd
Current assignee: CAV Ltd
Priority date: 1963-09-14
Filing date: 1964-09-14
Publication date: 1966-12-06
Anticipated expiration: 1983-12-06
Also published as: DE1273258B; GB1078402A; DE1273258C2

Description

6, 166 K. F. HUTCHEON 3.289590 LIQUID FUEL PUMPING APPARATUS FOR INTERNAL COMBUSTION ENGINES Filed Sept. 14, 1964 4 Sheets-Sheet l K. F. HuTcHEoN 3,289,590

LIQUID FUEL I UMPING APPARATUS FOR INTERNAL OMBUSTI NBS 0 ON ENGI Filed Sept. 14, 1964 4 Sheets-Sham 2 Dec. 6, 1966 K F. HUTCHEON 3,239,590

LIQUID FUEL PUMPING APPARATUS FOR INTERNAL COMBUSTION ENGINES Filed Sept. 14, 1964 4 Sheets-Sheet 3 Dec. 6, 1966 K. Fl HUTCHEON 3,289,590

LIQUID FUEL PING APPARATUS FOR INTERNAL BUSTION ENGINES Filed Sept. 14, 1964 4 Sheets-Sheet 4 United States Patent C 3,289,590 LIQUID FUEL PUMPING APPARATUS FOR INTERNAL COMBUSTION ENGINES Keith Finer Hutcheon, Gerrards Cross, England, assignor to C.A.V. Limited, London, England Filed Sept. 14, 1964, Ser. No. 396,076 Claims priority, applicatlion G121; Britain, Sept. 14, 1963,

6 Claims. (Cl. 103-2) This invention relates to liquid fuel pumping apparatus for use with internal combustion engines, and of the kind including an injection pump for supplying fuel to the engine in timed relationship thereto, a feed pump for supplying fuel to the injection pump, and an hydraulic governor for controlling the quantity of fuel supplied by the injection pump, the setting of said governor being determined by the output pressure of the feed pump.

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

According to the invention a pump of the kind specified is characterized by the provision of a centrifugally operable relief valve for controlling the output pressure of the feed pump.

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 view on the line 22 of FIGURE 1.

FIGURE 3 is a sectional View on the line 3-3 of FIGURE 1.

FIGURE 4 is a sectional view on the line 44 of FIGURE 1.

FIGURE 5 is an enlarged sectional side elevation of a portion of the apparatus shown in FIGURE 1.

FIGURE 6 is a sectional end view of the portion of the apparatus shown in FIGURE 5.

FIGURE 7 is a sectional end view similar to FIG- URE 6 showing a modification.

FIGURE 8 is a view similar to FIGURE 5 showing a further modification.

FIGURE 9 is a view taken on the line 9-9 of FIG- URE 8 and FIGURE 10 is a view taken on the line 10-10 of FIGURE 8.

Referring to the drawings there is provided a body part 11 in which is mounted a rotary cylindrical distributor 12. The distributor is arranged to be driven in timed relationship with the engine 13 with which the apparatus is associated. Near one end of the distributor is formed a transverse bore 14 in which is mounted a pair of reciprocable plungers 15, and the latter are arranged to be urged inwardly, as the distributor rotates, by cam lobes 16 which project inwardly from, and are equiangularly spaced about, the internal periphery of an annular ring 17, there being provided a pair of guided rollers 18 intermediate the plungers and ring respectively.

Formed in the distributor is a longitudinal bore 19 which communicates at one end with the transverse bore and which at one point is in communication with a plurality of equi-angularly spaced radial inlet passages 20. At another point the bore 19 is in communication with a 3,289,590 Patented Dec. 6, 1966 delivery passage 21 which is arranged to register with a plurality of equi-angularly spaced delivery ports 22, in turn, as the distributor rotates. The delivery ports are in communication respectively with injection nozzles 23 mounted to direct fuel into the combustion spaces of the engine respectively. It will be seen that the number of injector nozzles is the same as the number of engine cylinders and consequently the same as the number of inlet passages and cam lobes. In the particular example the number of engine cylinders is four, furthermore the delivery passage is disposed so as to be in register with a delivery port during the time when the plungers are being moved inwardly so that fuel contained within the transverse bore will be delivered to the engine.

At the other end of the distributor 12 is a feed pump the rotor 24 of which is connected to the distributor and is arranged to be driven thereby. The feed pump has an inlet port 25 which is connected through a filter 26 with a fuel tank (not shown). The feed pump also has an outlet port 27 through which fuel passes to a chamber 28 located in the body part.

Furthermore formed in the body part is a radially disposed cylindrical bore 29 in which is mounted a valve member 30. The latter is loaded by a governor spring 31 in a direction towards the distributor and is urged in the opposite direction, against the action of the spring by the pressure of fuel acting on its end remote from the spring. Fuel under pressure is delivered for this purpose from the chamber 28 through a passage 32 in the body, and a circumferential groove 33 in the distributor. The valve member 30 is provided with a reduced portion intermediate its ends which defines a control edge 34. The edge 34 controls the effective size of an inlet port 35 formed in the body part and disposed to register, in turn, with the inlet passages 20 at least during a portion of the time when the plungers are not being moved inwardly by the cam lobes. The annular spaces defined by the reduced portion of the valve member is in constant communication with a supply port 36 in the body part and the latter is in constant communication with a supply passage 37 formed in the distributor.

Also provided in the distributor is a stepped transverse bore 38 in which is mounted a two part relief valve generally indicated at 39 in FIGURE 1. In the narrower end of the bore 38 is mounted a slidable part 39 having a peripheral flange which can abut against the step in the bore to prevent the part falling out of the bore. In the wider end of the bore is mounted a further slidable part 40 having a sector shaped head 41. Within the part 40 is formed a blind bore 42 and this can communicate, by a way of a port 43 with the aforesaid supply passage 37. Furthermore also formed in the further part is a further port 44 and this co-operates with a spill port 45, formed in the disrtibutor, to control the amount of fuel spilled from the chamber 28 to the pump inlet 25, there being provided passages in the rotor of the feed pump and the body part for this purpose. Moreover located intermediate the two parts is a coiled compression spring 46, the purpose of which will be described, and the space between the parts is in communication with the inlet 25 of the feed pump by way of a passage 47.

In describing the operation of the apparatus it will be assumed that the engine is running at a constant speed. Starting with the distributor in the position shown in FIGURE 1, fuel is flowing to the transverse bore 14 from the feed pump via the supply passage 37, the supply port 36, the inlet port 35, one of the inlet passages and the longitudinal passage ll). Fuel flowing into the transverse bore causes the plungers to be moved outwardly and the amount of fuel flowing into the bore depends upon the setting of the valve member and the speed of rotation of the distributor. As the distributor further rotates from the position shown the inlet passage 20 moves out of register with the inlet port and the delivery of fuel to the bore ceases. As the distributor further rotates the delivery passage 21 registers with one of the delivery ports 22 and as soon as this occurs the plungers are moved inwardly by the effect of the cam lobes and fuel is expelled from the transverse bore and flows via the longitudinal passage, the delivery passage, and the one delivery port to one of the injection nozzles 23 of the engine, and from the nozzle to one of the combustion spaces of the engine. Further rotation of the distributor moves the delivery passage out of register with the delivery port and the cycle as described is repeated with fuel being delivered to the combustion spaces of the engine in turn. As previously mentioned the amount of fuel delivered can be adjusted by altering the setting of the valve member and if it is desired to increase the quantity of fuel delivered to the engine the strength of the governor spring is increased. This is achieved by moving an abutment 31a so as to compress the spring.

The valve member also acts as a governor and for this purpose the pressure of fuel acting on the end of the valve member in opposition to the spring is arranged to be dependent upon the speed of rotation of the engine. This is achieved by the relief valve the operation of which will be described. If, in use, the speed of the engine rises for a given setting of the abutment then the valve member will be moved against the action of its spring to reduce the effective size of the delivery port and so the rise in the speed of the engine will be minimised. Conversely if the engine speed falls for the same setting of the abutment the valve member will move to increase the effective size of the delivery port and consequently more fuel will be delivered to the engine to minimise the reduction in speed.

As has been described the output pressure of the feed pump is applied directly to the valve member 30 from the chamber 28, and the supply of fuel to the engine is controlled by the port 43. This port is always fully open during normal operation of the pump. Moreover the port 44 and spill port are always partly in register with each other when the pump is operating normally, and these two ports form a spill passage, the eflective size of which, and hence'the quantity of fuel spilled from the chamber 28 to the inlet of the feed pump, is dependent upon the setting of the part 40. The setting of the part 40 is dependent upon the fuel pressure acting on the part and the speed of rotation of the distributor. As the speed of rotation of the distributor increases so the centrifugal force acting on the head 41 increases and the part will be urged to close the spill passage constituted by the

ports

44 and 45. Acting in the opposite direction to the centrifugal force is a force produced by the pressure of fuel. Considering the case when the engine is running at an appreciable speed, so that the fuel pressure acting on the outer ends of the parts urges them into contact with each other against the action of the spring 46, the difference of the forces acting on the individual parts urges the parts as a single body, in a direction to oppose the centrifugal force. This is because the part 40 is of larger diameter than the part 39, and the parts assume an equilibrium position such that the force exerted by the fuel pressure just balances the centrifugal force. If the speed changes then the parts move to increase or decrease the size of the spill passage to change the fuel ressure to produce a new equilibrium position. By this means the fuel pressure is made dependent upon the square of the speed. The purpose of the spring 46 is to modify the speed pressure characteristic at low speeds since, until the fuel pressure is sufficient to move the parts into contact with each other the spill passage remains virtually closed.

In a modification shown in FIGURE 7 the parts are joined together and constitute a stepped part 50 the spring 46 being omitted and replaced by a pair of springs 51 mounted to act between the head of the part and the distributor. The effect of this is to modify the speed pressure characteristic by making the fuel pressure higher over the whole speed range.

As previously stated the feed pump inlet 25 is connected to a fuel supply tank through a filter 26 and if for any reason the supply to the feed pump is restricted then the output pressure of the feed pump will decrease. This has an effect on the setting of the valve member 30 and the latter will move to increase the quantity of fuel supplied to the engine with a resultant increase in the speed of the engine. This increase of engine speed may result in a slight rise in the output pressure of the feed pump but,

it has been found that this is insufficient to cause the valve member to regain control of the engine speed. The position is worsened by the fact that at high speeds the plungers 15 tend to act as a pump and themselves draw in fuel from the passages and spaces within the body part. Although the quantity of fuel within the body part is fairly small the associated engine may accelerate very quickly particularly if it is not loaded, and a dangerous speed may be attained before the fuel is consumed. The purpose of the port 43 is to prevent this happening. Should the output pressure of the feed pump start to fall the centrifugal force will move the part 40 in a direc tion to reduce the size of the spill passage, constituted by the

ports

44, 45, in an attempt to increase the output pressure of the feed pump however, should the pressure continue to fall the part will move further to close the port 43 and so prevent further fuel being delivered to the transverse bore. It should be noted that the value member 30 is always exposed to the output pressure of the feed pump.

In a modified form of the relief valve, as illustrated in FIGURES 8, 9 and 10, there is provided a stepped transversely disposed bore 54. Moreover formed in the distributor is a passage 55 which is tangentially disposed with respect to the bore and which cuts into the wider portion thereof, the passage extends through the distributor and communicates with the chamber 28. Near the opposite end of the bore is formed an annular recess 56 which is also in communication with the chamber 28 through passages 57. Furthermore intermediate the recess 56 and the passage 55 is formed a further recess 58 which communicates with the feed pump inlet through a passage 59.

Located in the bore is a part 60 which is formed integrally with a sector shaped head 61. The part is provided with a first land 62 having a diameter equal to that of the narrower portion of the bore and a second land 63 having a diameter equal to that of the wider portion of the bore. Moreover, a third land 64 is provided to close the wider end of the bore. Furthermore diametrically opposite the point of entry of the passage 55 into the bore is formed a chamber 65 from which extends the supply passage 37. As in the modification of the previous example a pair of springs 65 is provided to modify the pressure/ speed characteristicof the relief valve.

The operation of the relief valve is substantially as was described for the first example and in this case the amount of fuel spilled is controlled by the size of the gap between the inner edge of the land 62 and the adjacent edge of the recess 56. As in the previous example in the event of the output pressure of the feed pump falling owing to an interruption in the supply thereto the part will be moved by the centrifugal force so that the land 63 isolates the chamber 65 from the passage 55 and so prevents fuel being drawn from the chamber 28 by the plungers 15.

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

1. Liquid fuel pumping apparatus for supplying fuel to an internal combustion engine, and comprising in combination, an injection pump which is arranged to be driven in timed relationship to an engine for supplying fuel thereto, a feed pump for supplying fuel to the injection pump, passage means connecting said feed pump to said injection pump, governor means in said passage means for controlling the amount of fuel fed by the feed pump to the injection pump, said governor means being in part, responsive to the output pressure of the feed pump, a valve for controlling communication between the feed pump and said passage means, centrifugal biasing means acting to close said valve as the engine speed increases, fluid pressure biasing means acting to open said valve with a force dependent upon the output pressure of the feed pump, said centrifugal biasing means being such that at any given speed, the valve will be moved to its closed position to shut off the supply of fuel to the injection pump when the force of said centrifugal biasing means exceeds the force dependent upon the output pressure of the feed pump.

2. Liquid fuel pumping apparatus for supplying fuel to an internal combustion engine, and comprising an injection pump which is arranged to be driven in timed relationship to the engine for supplying fuel thereto, a feed pump for supplying fuel to the injection pump, governor means for controlling the amount of fuel fed by the feed pump to the injection pump, said governor means being in part responsive to the output pressure of the feed pump, a rotary part which is arranged to be driven at a speed dependent upon the speed at which the engine is operating, a radial bore defined in said part, a valve member slidable within said bore, and arranged to be subjected to the output pressure of the feed pump, passage means defined in said valve member through which fuel is fed from the feed pump to the injection pump, said valve member being arranged to control the flow of fuel through said passage means, a head mounted upon said valve member, whereby as the part rotates, a force will be applied to the valve member to move the valve member in a direction to prevent the flow of fuel through said passage means, the movement of the valve member in this direction being resisted by the force developed on the valve member by the pressure of fuel acting thereon.

3. Liquid fuel pumping apparatus as claimed in claim 2 in which said feed pump takes suction from a source of fuel at a lower pressure including further passage means in said valve member through which fuel under pressure from the feed pump can fiow to said source of fuel at a lower pressure, the flow of fuel through said further passage means being controlled by movement of said valve member, whereby the pressure of fuel delivered by the feed pump will vary as the square of the speed at which the part rotates.

4. Liquid fuel pumping apparatus for use with internal combustion engines, and of the kind comprising in combination a body part, a rotary distributor mounted in the body part, and adapted to be driven in timed relationship to the engine with which the apparatus is associated, a bore formed in the distributor, a reciprocable plunger slidably mounted in the bore, a cam for imparting inward movement to the plunger as the distributor rotates, a delivery passage in communication with said bore, a delivery port in the body part, and disposed so that the delivery passage can register therewith during the time the plunger is moved inwardly by the cam, said delivery port being adapted for connection to a combustion space of the engine, an inlet passage in the distributor in communication with said bore, and an inlet port in the body part and with which the inlet passage registers at least during part of the time when the delivery port is out of register with the delivery passage, a feed pump mounted in the body part, said feed pump having an inlet and an outlet, a hydraulic governor mounted in the body part and connected intermediate the outlet of the feed pump and the inlet port for controlling the quantity of fuel delivered to the bore, the setting of said governor being in part, dependent upon the pressure of fuel delivered by said feed pump, a transversely disposed drilling in the distributor, a valve member including a port slidably mounted in said drilling, said valve member having a head formed on one end thereof, and arranged so that when the distributor is rotated, the centrifugal force acting on the head of said valve member will bias the valve member in one direction, a surface being provided on the valve member against which the output pressure of the feed pump acts to produce a force to oppose said centrifugal force, passage means defined in the distributor through which fuel from the outlet of the feed pump flows to the governor, said port being positioned with respect to said passage means to control the flow of fuel through said passage means, the arrangement being such that in the event of the force produced by the fuel pressure acting against said surface being insufficient to balance the centrifugal force, the valve member will move to close said port, to prevent further fuel being supplied to the engine.

5. Liquid fuel pumping apparatus as claimed in claim 4 including further passage means in the distributor and body part, and through which the outlet of the feed pump is in communication with the inlet thereof, a further port in said valve member located with respect to said further passage means in such a position that as the output pressure of the feed pump increases, more fuel will flow through said further passage means whereby the output pressure of the feed pump will vary as a function of the square of the speed at which the distributor is driven.

6. A liquid fuel pumping apparatus for use with internal combustion engines, and of the kind comprising in combination a body part, a rotary distributor mounted in the body part and adapted to be driven in timed relationship to the engine with which the apparatus is associated, a bore formed in the distributor, a reciprocalble plunger slidably mounted in the bore, a cam for imparting inward movement to the plunger as the distributor rotates, a delivery passage in communication with said bore, a delivery port in the body part, and disposed so that the delivery passage can register therewith during the time the plunger is moved inwardly by the cam, said delivery port being adapted for connection to a combustion space of the engine, an inlet passage in the distributor in communication with said bore, an inlet port in the body part and with which the inlet passage registers at least during a part of the time when the delivery port is out of register with a delivery passage, a feed pump mounted in the body part, said feed pump having an inlet and an outlet, a hydraulic governor mounted within the body part for controlling the quantity of fuel delivered to the bore, the setting of said governor being in part dependent upon the pressure of fuel delivered by said feed pump, a transversely disposed drilling formed in the distributor, a valve member slidably mounted in said drilling, a head connected to one end of the valve member, said head projecting from the distributor and rotatable therewith within an annular chamber defined by said distributor and said body part, said chamber being in communication with the outlet of the feed pump, a surface being provided on the valve member against which the output pressure of the feed pump can act to produce a force to oppose the centrifugal force resulting from rotation of the head, first and second ports in the wall of said transversely disposed drilling, passage means in the distributor and body part through which said first port is in communication with the governor, further passage means in the distributor and body 7 part through which said second port is in communication with the inlet of the feed pump, first and second grooves formed on the periphery of the valve member for registration with said first and second ports respectively, said first and second grooves being in communication with said annular chamber, the axial position of the ports and groove being such that in the event of the output pressure of the feed pump rising for a given speed of the distributor, said second port Will be uncovered to a greater extent to allow fuel from the chamber to be spilled to the inlet of the feed pump, and whereby in the event that the output pressure of the feed pump falls, the second port will be covered to a greater extent to reduce the spillage of fuel, and in the event that the fuel pressures falls further, the

bore.

References Cited by the Examiner UNITED STATES PATENTS Roosa 10'3-2.1

Seaver 1032.1

Hess 1032.1

Liardet 1 10-32.1 Evans 1032.1

Volossevich 103-2.1

Hutcheon 1032.1

Knudson 1032.1

Hutcheon 103-2.1

MARK NEWMAN, Primary Examiner.

first port will be closed to cut off the flow of fuel to the 15 MARTIN SCHWADRON, Examiner- W. I. KRAUSS, Assistant Examiner.