GB2190711A

GB2190711A - Liquid fuel pumping apparatus

Info

Publication number: GB2190711A
Application number: GB08709884A
Authority: GB
Inventors: Ian Roy Thornthwaite; Paul Raymond Smith
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1986-05-23
Filing date: 1987-04-27
Publication date: 1987-11-25
Also published as: JPS62288363A; GB8612622D0; DE3717361A1; ES2005584A6; GB8709884D0; GB2190711B; FR2599089A1; IT8720341A0; US4759694A; IT1203982B

Description

G132 19071 1A 1 SPECIFICATION tributor member or said part, said sleeve

con trolling the flow of liquid through said port Liquid fuel pumping apparatus from said chamber and the relative position of the sleeve and port being such that axial This invention relates to liquid fuel pumping 70 movement of the distributor member due to apparatus of the kind comprising a rotatable the interaction of said stop surfaces will cause and axially movable distributor member closure of said port, a liquid supply path to housed within a body, a reciprocable pump said chamber and valve means in said supply plunger housed within a bore formed in the path, said valve means being arranged to pre distributor member, cam means mounted in 75 vent flow of liquid along said supply path the body for effecting inward movement of from the chamber.

the plunger as the distributor member rotates, Examples of fuel pumping apparatus in ac passage means in the distributor member and cordance with the invention will now be de body through which fuel can flow to the bore scribed with reference to the accompanying to effect outward movement of the plunger 80 drawings in which:

and through which fuel can flow to an outlet Figure 1 is a sectional side elevation of a during inward movement of the plunger by the portion of the apparatus in accordance with cam means, inclined stop surfaces defined on the invention, and a part carried by the distributor member and a Figures 2-5 show modifications to the part housed within the body, said stop sur85 example seen in Figure 1.

faces co-operating to limit the extent of out- Referring to Figure 1 of the drawings the ward movement of the plunger and thereby apparatus comprises a body 10 in which is the quantity of fuel supplied through the outlet fixed a sleeve 11, the sleeve mounting a ro in accordance with the axial position of the tary distributor member 12 which projects distributor member, resilient means biasing the 90 from the sleeve and which has an enlarged distributor member in the direction to increase portion 13.

the amount of fuel flow through the outlet, a Surrounding the enlarged portion 13 is an chamber defined in the body, said distributor annular member 14 which is integral with a member or a part coupled thereto, extending drive shaft 15 adapted in use to be driven in into the chamber and being subject to the 95 timed relationship with the associated engine.

pressure in said chamber whereby an increase The part 14 is provided with a pair of axially in the pressure in the chamber will cause extending slots 16 in which is located a pair movement of the distributor member against of drive plates 17 coupled to the distributor the action of the resilient means in a direction member on opposite sides of the enlarged to reduce the amount of fuel delivered through 100 portion 13 thereof.

said outlet and means for controlling the pres- Formed in the enlarged portion 13 of the sure of liquid in said chamber. distributor member is a transversely extending A known method of controlling the pressure bore 18 in which is mounted a pair of pump in the chamber is to provide a sleeve on the ing plungers 19. At their outer ends the plun distributor member or said part, the sleeve 105 gers engage shoes 20 respectively which form being axially movable and controlling the part of a pair of cam followers, the cam fol opening of a port which is connected to the lowers further including rollers 21 which are chamber and through which liquid can escape located within grooves formed in the outer from the chamber. Providing the port is cor- surfaces of the shoes. The shoes and rollers rectly positioned relative to the sleeve it can 110 are located against axial movement by reason be arranged that the initial axial movement im- of the fact that they are located between the parted to the distributor as a result of engage- drive plates 17. Moreover, the rollers 21 pro ment of said stop surfaces, will cause closure ject through the slots 16 into engagement of said port and therefore prevent the escape with the internal peripheral surface of a cam of liquid from said chamber through the port. 115 ring not shown, the cam ring defining a plural It is however necessary to supply liquid to ity of cam lobes which as the distributor said chamber through a flow path from a member rotates, will engage the rollers to im source of liquid and in order to achieve a hy- part inward movement to the plungers 19.

draulic lock in the chamber so as to minimise The internal surface 22 of the part 14 is movement of the distributor member it is 120 flared outwardly to define a stop surface for necessary to prevent liquid flow along said co-operation with stop surfaces 23 formed on flow path. the shoes 20. The distributor member is bi The object of the present invention is to ased towards the right as seen in the drawing provide an apparatus of the kind specified in a by means of a coiled compression spring 24.

simple and convenient form. 125 Communicating with the bore 18 is a longi According to the invention a liquid fuel tudinal drilling 25 which communicates with a pumping apparatus of the kind specified com- first longitudinal groove 26 formed on the prises a port formed on the periphery of the periphery of the distributor member and a fur distributor member or on a part connected ther longitudinal groove 27 also formed on the thereto, an axially movable sleeve on the dis- 130 periphery of the distributor member at an axi- 2 GB 2 190 711 A 2 ally spaced position. The groove 26 can regis- tending to reclose the port 32. Fuel is sup ter in turn with a plurality of inlet ports 28 plied to the chamber through the flow path 34 which are connected to a source of fuel under the fuel flow causing the valve member of the pressure conveniently a low pressure pump check valve to be lifted from its seating. The driven by the drive shaft 15. The groove 27 70 flow through the flow path is at a restricted can register in turn with outlet ports 29, only rate so that in practice the distributor member one of which is shown, formed in the sleeve will assume an equilibrium position with the and connected to outlets on the body to port 32 slightly open. When, during the oper which, in use, the injection nozzles respec- ation of the apparatus, the stop surfaces 23 tively of the associated engine are connected. 75 engage the stop surface 22 a reaction force is The communication of the groove 27 with an applied to the distributor member which tends outlet 29 is arranged to take place just before to urge it towards the right. Such movement the plungers 19 are moved inwardly by the will cause closure of the port 32 and also cam lobes and during such inward movement closure of the valve 35 so that an hydraulic fuel will be displaced through one of the out- 80 lock will be created in the chamber 30 which lets to a combustion chamber of the associ- will prevent further movement of the distribu ated engine. As the distributor member con- tor member.

tinues to rotate the groove 26 will be brought Referring now to Figure 2, the general de into register with a port 28, the groove 27 tails of the apparatus are as with the example moving out of register with a port 29. Fuel 85 of Figure 1 and the escape of fuel from the can now flow to the bore 18 to effect out- chamber 30 takes place by way of the pas ward movement of the plungers 19 and the sage 33 and the port 36 as in the previous cam followers. The extent of outward move- example. The flow path of fuel to the chamber ment is limited by the engagement of the stop does however include the port 36 and the surfaces 23 with the stop surface 22. As the 90 passage 33 and as will be seen from Figure 2 distributor member continues to rotate the the sleeve 31 is provided with two circumfer groove 26 will move out of register with the ential grooves 37, 38 on the internal surface port 28 and the groove 27 will move into of the sleeve. The groove 38 is in permanent register with the next outlet 29. Thereafter the communication by way of a passage 39 in the cycle of operations as described is repeated 95 distributor member, with a supply passage 40 with fuel being supplied to the combustion in the body. The grooves 37 and 38 are inter chambers of the engine in turn. connected through a non-return valve 41 The extent of outward movement of the which is disposed to allow flow of fuel from plungers determines the amount of fuel which the groove 38 to the groove 37 but to pre is supplied to the engine and by moving the 100 vent flow in the opposite direction.

distributor so the quantity of fuel can be In operation, as the sleeve is moved to varied. wards the right as seen in Figure 2, the port As described above the distributor member 36 will be uncovered to a space in the body is biased towards the right by the action of and fuel will escape from the chamber 30 al- the spring 24 in other words, the distributor 105 lowing the distributor member to move to member will move in a direction to increase wards the right until the port 36 is again cov the amount of fuel supplied to the engine. ered. If the sleeve is moved towards the left This movement of the distributor member is as seen in Figure 1, the port 36 is opened to opposed by the fuel pressure within a cham- the groove 37 and fuel can flow past the ber 30 defined in the body and into which the 110 valve 41 to the groove 37 and hence through end of the distributor member remote from the port 36 into the chamber 30. As a result the spring projects. the distributor member will also move towards The escape of fuel from the chamber 30 is the left until the port 36 is again covered. The controlled by means of a sleeve 31 which is width of the land defined by the sleeve and mounted about the distributor member and is 115 which controls the port is only slightly wider axially movable relative thereto. The sleeve in than the diameter of the port and when the use will be connected to a speed governor distributor member has the aforesaid force ap mechanism. The sleeve controls the opening plied to it when the stop surfaces engage of a port 32 formed in the distributor member with each other, the port will tend to be unco- and connected by means of a passage 33 120 vered to the groove 37. In this situation how with the chamber 30. Fuel is supplied to the ever the flow of fuel from the chamber is chamber from a source of liquid conveniently prevented by the action of the valve 41.

the aforesaid low pressure pump, by way of a The arrangement shown in Figure 3 is sub supply path 34 and located in the supply path stantially identical to the arrangement shown is a spring loaded check valve 35. In use, as 125 in Figure 2 with the exception that the non the sleeve is moved towards the right, the return valve indicated at 42, is located in the port 32 will be uncovered and this will allow body 10 of the apparatus and the two fuel to escape from the chamber 30 causing a grooves 37, 38 are replaced by a single reduction of pressure therein. The distributor groove 43.

member will therefore move towards the right 130 Turning now to Figure 4, the function of the 3 GB 2 190 711 A 3 valve 42 is replaced by a groove 44 on the of liquid in said chamber, a port formed on periphery of the distributor member and which the periphery of the distributor member or on is connected to the passage 39. The groove a part connected thereto, an axially movable 44 is positioned to register with a series of sleeve on the distributor member or said part, supply ports 45 formed in the sleeve 11 and 70 said sleeve controlling the flow of liquid which are connected to the aforesaid low through said port from said chamber and the pressure pump. It is arranged that the groove relative position of the sleeve and port being 44 can communicate with a port 45 for a such that axial movement of the distributor limited period following delivery of fuel and member due to the interaction of said stop before there is any chance of the stop faces 75 surfaces will cause closure of said port, a 23 and 22 moving into engagement with each liquid supply path to said chamber and valve other whatever the axial setting of the distri- means in said supply path, said valve means butor member. Thus a hydraulic lock will be being arranged to prevent flow of liquid along created in the chamber 30 as with the said supply path from the chamber.

Claims

example of Figure 3. 80
2. An apparatus according to Claim 1 in

In the example of Figure 5 the groove 44 is which said supply path comprises a passage omitted and is replaced by a circumferential in the body communicating directly with said groove 46 which is in constant communication chamber, said valve means being positioned in with the fuel supply. In this example the port said passage.

36 is prevented from communicating with the 85
3. An apparatus according to Claim 1 in chamber 30 except immediately following de- which said supply path includes said port, said livery of fuel and before there is a chance of sleeve having a circumferential groove formed the stop surfaces engaging with each other. on its internal peripheral surface, the groove For this purpose the circumferential groove 47 defining a land with an end surface of the formed on the internal surface of the sleeve is 90 sleeve, said land being positioned to obturate provided with a plurality of grooves 48 which said port, and the groove forming part of the will be exposed to the port 36 in turn when liquid supply path to said chamber.

the sleeve is moved towards the left to re-
4. An apparatus according to Claim 3 in duce the amount of fuel supplied to the asso- which said supply path includes a further ciated engine. Again an hydraulic lock is 95 groove on the internal peripheral surface of created at the instant when the stop surfaces said sleeve, the valve means being located in engage with each other. a passage in the sleeve connecting the two grooves, and passage means in the distributor CLAIMS member and body for connecting said further 1. A liquid fuel pumping apparatus compris- 100 groove to a source of liquid.

ing a rotatable and axially movable distributor
5. An apparatus according to Claim 3 in member housed within a body, a reciprocable cluding passage means in the distributor mem pump plunger housed within a bore formed in ber and body for connecting said groove with the distributor member, cam means mounted a source of liquid, said valve means being lo- in the body for effecting inward movement of 105 cated in the body.

the plunger as the distributor member rotates,
6. An apparatus according to any one of passage means in the distributor member and the preceding claims in which said valve body through which fuel can flow to the bore means comprises a spring loaded check valve.

Of to effect outward movement of the plunger
7. An apparatus according to Claim 3 in- and through which fuel can flow to an outlet 110 cluding a passage formed on the distributor during inward movement of the plunger by the member, the passage extending to a groove cam means, inclined stop surfaces defined on on the periphery of the distributor member, a part carried by the distributor member and a and ports in the body opening onto the peri part housed within the body, said stop sur- phery of the distributor member, said groove faces co-operating to limit the extent of out- 115 being positoned to register with said ports in ward movement of the plunger and thereby turn for a limited period following delivery of the quantity of fuel supplied through the outlet fuel and before engagement of said stop sur in accordance with the axial position of the faces.

distributor member, resilient means biasing the
8. An apparatus according to Claim 3 in distributor member in the direction to increase 120 which the valve means comprises a plurality the amount of fuel flow through the outlet, a of axial grooves extending from said circum chamber defined in the body, said distributor ferential grooves towards said end surface, member or a part coupled thereto, extending said axial grooves being positioned to register into the chamber and being subject to the with said port in turn for a limited period fol pressure in said chamber whereby an increase 125 lowing delivery of fuel and before engagement in the pressure in the chamber will cause of said stop surfaces and when the sleeve has movement of the distributor member against been moved to increase the pressure in said the action of the resilient means in a direction chamber.

to reduce the amount of fuel delivered through
9. A liquid fuel pumping apparatus compris said outlet, means for controlling the pressure 130 ing the combination and arrangement of parts 4 GB219071 1A 4 substantially as hereinbefore described with reference to Figure 1 of the drawings.
10. A liquid fuel pumping apparatus comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figure 1 as modified by Figure 2 of the drawings.
11. A liquid fuel pumping apparatus comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figure 1 as modified by Figure 3 of the drawings.
12. A liquid fuel pumping apparatus comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figure 1 as modified by Figure 4 of the drawings.
13. A liquid fuel pumping apparatus comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figure 1 as modified by Figure 5 of the drawings.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987. Published at The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.