US3489093A

US3489093A - Liquid fuel pumping apparatus

Info

Publication number: US3489093A
Application number: US759078A
Authority: US
Inventors: John Charles Powell Thornber
Original assignee: CAV Ltd
Current assignee: CAV Ltd
Priority date: 1968-09-11
Filing date: 1968-09-11
Publication date: 1970-01-13
Anticipated expiration: 1987-01-13

Description

Jan. 13, 1970 J. c. P.- THQRNBER 3,489,093

LIQUID FUEL PUMPING APPARATUS Filed Sept. 11, 1968 2 Sheets-Sheet 1 lNVENT R filfmlm "M2 ORNEYS Jan. 13, 1970 P, THORNBER 3,489,093

LIQUID FUEL PUMPING APPARATUS Filed Sept. 11, 1968 r 2 Sheets-Sheet 2 INV NT R fa 91W JUN/261% ATTORNEY$ United States Patent 3,489,093 LIQUID FUEL PUMPING APPARATUS John Charles Powell Thornber, Peterborough, England,

assignor to C.V.A., Limited, London, England, a British company Filed Sept. 11, 1968, Ser. No. 759,078

Int. Cl. F0411 13/02, 23/04; F02d 1/04 US. Cl. 103-2 Claims ABSTRACT OF THE DISCLOSURE A liquid fuel pumping apparatus for supplying fuel to an internal combustion engine and including a bore in which is mounted at least one reciprocable pumping plunger an outlet from a pumping chamber and through which fuel flows to an associated internal combustion engine, and a spill path from said pumping chamber, the spill path being arranged to be opened when the plunger attains a predetermined position during its pumping stroke. Valve means is provided to control the pressure within the pumping chamber when said spill path has been opened.

This invention relates to liquid fuel pumping apparatus for supplying fuel to an internal combustion engine and of the kind comprising in combination, a bore, a reciprocable pumping plunger mounted within said bore, and an outlet from the pumping chamber as defined by the bore and plunger.

The object of the invention is to provide such an apparatus in a simple and convenient form. 1

In the accompanying drawings:

FIGURE 1 is a sectional side elevation of one example of a liquid fuel pumping apparatus in accordance with the invention.

FIGURE 2 is a diagrammatic view of part of the apparatus of FIGURE 1 and FIGURE 3 is a view similar to FIGURE 1 showing part of a modified form of the apparatus.

As shown in FIGURE 1 the apparatus comprises a distributor member 10 which is mounted for rotation within a surrounding body 11 which also includes a sleeve 12. The distributor member is arranged to be driven in timed relationship with the engine with which the apparatus is associated. At one end of the distributor member 'is formed a transversely extending bore 13 in which is mounted a pair of reciprocable pumping plungers 14. Each plunger has associated therewith a shoe which mounts a roller 16 which bears upon the internal periphcry of a surrounding annular cam ring 17. The annular cam ring 17 is provided with a plurality of inwardly extending cam lobes the profile of which is seen in FIG- URE 2.

The transverse bore 13 is in communication with a longitudinally extending passage 18 formed in the distributor member and which opens into a delivery chamber 19. The delivery chamber accommodates a fluted delivery valve element 20 which is slidable in the delivery chamber 19 and which is loaded in a direction towards the transverse bore 13 by means of a coiled compression spring 21. Furthermore, the extent of movement of the delivery valve element against the action of the spring 21 is limited by a stop 22.

The delivery valve element 20 comprises a fluted portion and a collar portion 23, the collar portion being a close sliding fit within the delivery chamber 19. The end portion of the delivery chamber remote from the transverse bore is of enlarged form and extendingv fromthis portion of the chamber is a delivery passage 24 which is arranged to register in turn and as the distributor rotates with a plurality of outlet ports 24a formed in the body.

Patented Jan. 13, 1970 The outlet ports are in use, connected to the injection nozzles 50 respectively of the associated engine. Extending from intermediate the ends of the narrower portion of the delivery chamber 19 is a pair of inlet passages 26. The outer ends of the inlet passages are in constant communication with an inlet port 25 formed in the body part and in communication with a source of fuel under pressure. This source of fuel comprises a vane type feed pump 51 the rotary part of which is mounted at the end of the distributor member 10. Moreover, the outlet pressure of the feed pump is controlled by a valve 52 such that it varies in accordance with the speed at which the distributor member is driven. The feed pump 51 has an inlet 53 and an outlet connected to a supply passage 54 formed in the body part. For controlling the quantity of fuel which flows through the inlet port 25 and the inlet passages there is provided an adjustable throttle member 55 the setting of which is controlled by an operator or by a speed sensitive governor (not shown).

The inlet passages 26 each incorporate non-return valves 56 of the plate variety and these valves are arranged to permit the flow of fuel from the inlet port 25 to the chamber 19 as will be explained.

The operation of the apparatus so far described is as follows. At the start of the inward movement of the pumping plungers 14 the delivery valve element 20 will be in its extreme left hand position under the action of the spring 21. Moreover, the delivery passage 24 will be in register with one of the outlet ports 24a. As the plungers move inwardly fuel will be transferred from the transverse bore 13 and will flow along the longitudinal passage 18 into the delivery chamber 19. The effect of this is to move the delivery valve element against the action of the spring 21 and during this process fuel will flow to the appropriate outlet port. During this movement of the delivery valve element the collar portion 23 will lie within the wider portion of the delivery chamber. At the end of the injection period which will be more fully described later in the specification, the delivery valve element moves to the left under the influence of its spring and in so doing a predetermined quantity of fuel flows from the outlet port into the wider portion of the delivery chamber. During further rotation of the distributor member the delivery passage 24 is moved out of register with the outlet port and as soon as the plungers are permitted outward movement by the cam fuel flows through the inlet passages 26 past the valves 56, to the transverse bore 13 thereby moving the plungers outwardly ready for the next injection stroke. The rate at which fuel can flow through the inlet ports is controlled by the setting of the throttle member 55 so that the final quantity of fuel which flows to the transverse bore 13 can be controlled.

In order to accurately determine the end of injection fuel is spilled through a spill port, from the transverse bore 13. The spill port comprises drillings 30 in one of the plungers which communicates with a groove 31 formed in the periphery of the plunger. The groove 31 co-operates With a further groove 32 which is formed in the transverse bore 13. This groove is in constant communication with a spill port 33 which is normally closed by a spring loaded valve element 34. Towards the end of the inward movement of the plungers the groove 31 registers with the groove 32 and fuel within the transverse bore which is under extremely high pressure, flows to the spill port 33 and moves the valve element 34 against the action of its spring. After a predetermined movement the valve element exposes a spill passage 35 and through which the remaining quantity of fuel displaced from the transverse bore 13 passes. The pressure of fuel within the transverse bore 13 is therefore suddenly lowered to a valve which is determined by the strength of the spring which loads the valve element 34 and also the area of the valve element. The lowered pressure is low enough to allow the delivery valve 20 element to move to the left as has been described.

Referring to FIGURE 2 the point on the cam lobe at which the grooves 31 and 32 are brought into register is indicated at B and the point A indicates the position at which inward movement of the plunger occurs. The position of the point A is of course variable and depends on the quantity of fuel admitted to the transverse bore during the filling stroke of the apparatus.

In order to provide an excess of fuel for starting purposes the spill port 33 is closed by means of :a manually operable valve 36, so that no fuel is spilled from the transverse bore and fuel continues to be supplied to the engine until the crest of the cam lobe is reached. The valve 36 is shown in FIGURE 3 and also shown is a modification in which the spring loading of the valve element 34 is adjusted in accordance with the speed at which the apparatus is driven. For this purpose a piston 37 is provided which is acted upon by the output pressure of the feed pump. The piston 37 serves as an abutment for the spring of the valve element 34 so that as the speed at whichthe apparatus is driven increases the force exerted by the spring on the valve element will also increase. The action of this is to increase the residual pressure in the transverse bore 13 in accordance with the speed and this results in an increased quantity of fuel being supplied to the engine.

If desired the spring which loads the valve element 34 may be omitted and a peg 38 provided on the piston 37 for contact with the element 34. In this manner the piston 37 acts as a biasing member for the valve element.

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

1. A liquid fuel pumping apparatus for supplying fuel to an internal combustion engine and comprising in combination: a body having a bore; at least one reciprocable pumping plunger mounted within the bore; an outlet from the pumping chamber as defined by the bore and plunger; a spill path from said pumping chamber, said spill path being opened by the plunger at a predetermined point during its discharge stroke, and a control valve for controlling the outflow of fuel from said pumping chamber after said spill path has opened, and while the plunger is in its discharge stroke.

2. A liquid fuel pumping apparatus for supplying fuel to a multi cylinder internal combustion engine and comprising in combination: a body part; a rotary distributor member mounted in the body part and adapted to be driven in timed relationship with an engine with which the apparatus is associated; an injection pump having at least one pumping plunger; cam means for effecting inward movement of the plunger in timed relationship with the engine; a longitudinal passage in the distributor member in communication with the pumping chamber of the injection pump; a delivery passage extending from said longitudinal passage; a plurality of outlet ports formed 15. in the body part and withwhich the delivery passage registers in turn as the distributor member rotates during successive pumping strokes of the injection pump; a spill path from said pumping chamber, said spill path being opened by the plunger at a predetermined point during the inward movement thereof; and a control valve associated with said spill passage forcontrolling. the outflow of fuel from saidpumping chamber after said spill path has been opened and during the remaining inward movement of the plunger."

3. An apparatus as claimed in claim 2 in which said spill path is formed at least in part, in said plunger.

4. An apparatus as claimed in claim 3 including valve controlled passage means for admitting fuel to the pumping chamber during a filling stroke of the injection pump.

5. An apparatus as claimed in claim 4 including a feed pump for supplying fuel to the injection pump during the filling strokes thereof, throttle means for controlling the flow of fuel and further valve means for controlling the outlet pressure of the feed pump so that it varies in accordance with the speed at which the apparatus is driven.

6. An apparatus as claimed in claim 5 in which said control valve comprises a loaded relief valve including a valve element slidable in a bore, the valve element being acted upon by the pressure of fuel in the pumping chamber whensaid spill path is opened by said plunger, against the action of its loading to open a port formed in the wall of the bore in which said valve element is mounted.

7. An apparatus as claimed in claim 6 in which said valve element is loaded by a coiled compression spring.

8. An apparatus as claimed in claim 7 in which the abutment for the spring comprises a fluid pressure operable piston acted upon by the output pressure of the feed pump in a direction to increase the force acting to close the valve element.

9. An apparatus as claimed in claim 6 in which the valve element is loaded by a force created by the output pressure of the feed pump acting upon a surface.

10. An apparaus as claimed in claim 6 including manually operable valve means operable to prevent the flow of fuel through said spill path.

References Cited UNITED STATES PATENTS 3,179,100 4/1965 Glikin 103-2 3,196,796 7/1965 Channing et al 103-2 3,228,339 1/1966 Evans et a1 103-2 3,263,614 8/1966 Kemp 103-2 3,292,546 12/1966 Evans 103-2 3,416,505 12/1968 Barber 103-2 HENRY F. RADUAZO, Primary Examiner U.S. 01. x12. 103-5; 123-139,