US3340860A

US3340860A - Fuel injection pump valves

Info

Publication number: US3340860A
Application number: US449138A
Authority: US
Inventors: Ernest R Groschel; Watson Harry
Original assignee: Ruston and Hornsby Ltd
Current assignee: Ruston and Hornsby Ltd
Priority date: 1964-04-25
Filing date: 1965-04-19
Publication date: 1967-09-12
Anticipated expiration: 1984-09-12
Also published as: DK111547B; GB1056337A; DE1297934B; NL6505133A; SE302542B

Description

p 1967 E. R. GROSCHEL ETAL 3,340,860

FUEL INJECTION PUMP VALVES Filed April 19, 1965 3 Sheets-Sheet 1 Sept 1967 E. R. GROSCHEL ETAL 3,340,860

FUEL INJECTION PUMP VALVES Filed Aprii 19, 1965 5 Sheets-Sheet 2 E- R. GROSCHEL ETAL Sept. 12, 1967 Filed April 19. 1965 FUEL INJECTION PUMP VALVES 5 Sheets-Sheet 3 United States Patent 3,340,860 FUEL INJECTION PUMP VALVES Ernest R. Groschel and Harry Watson, Lincoln, England,

assignors to Ruston & Hornsby Limited, Lincoln, England, a company of Great Britain Filed Apr. 19, 1965, Ser. No. 449,138 Claims priority, application Great Britain, Apr. 25, 1964,

17,228/64 6 Claims. (Cl. 123-139) ABSTRACT OF THE DISCLOSURE A fuel injector control valve assembly connected between the pump and the injector of a compression ignition internal combustion engine has a unitary valve body with a pair of fluid passageways therethrough, one serving to admit fuel to the injector and the other to bleed fuel back from the injector to a spill space. These passageways are normally closed by a pair of interconnected oppositely facing fluid actuated valves so that fuel under pressure is first admitted through one valve to the injector and following injection excess fuel is bled back to a spill space through the other valve.

This invention relates to fuel injection pumps for diesel or dual fuel engines, and particularly to pump delivery and pressure unloading valves.

At the termination of fuel delivery from the pump to the injector, it is desirable to relieve rapidly the pressure of the fuel trapped between the pump delivery valve and the injector in order to facilitate rapid injector needle closure and prevent the formation of pressure waves which may cause secondary injection into the engine cylinder. Various valves are known to achieve such unloading, but they do not attain all the following desiderata:

(1) Suppress secondary fuel injection over the whole engine load and speed range.

(2) Deal with the various flow requirements resulting from (1).

(3) Respond rapidly.

(4) Unload larger amounts at high line pressures and smaller amounts at lower line pressures to leave a substantially constant residual line pressure. This ensures that no voids are formed in the fuel at light operating loads, and thus prevents cavitation erosion in pipes and passages.

(5) Be of simple and cheap design.

(6) Be easily serviceable.

(7) Be removable and replaceable as a sub-assembly.

By the use of the present invention, the main features of which are set out severally in the claims that end this specification, it is possible to attain many or indeed all of these desiderata.

The following description relates to the drawing accompanying the provisional specification, now for convenience referred to as FIGURE 1, and to the drawings accompanying this specification, for convenience referred to as FIGURES 2 and 3; showing in all, three embodiments of the invention, all being by way of example only.

In FIGURE '1, the fuel pump 1 is a conventional diesel engine fuel pump delivering pressurized fuel to a delivery valve upon closure of its inlet port by its plunger and terminating delivery upon opening of its spill port; therefore only the novel combined delivery and unloading valve is shown, in part-sectioned detail.

The pump 1 delivers pressurised fuel through passages 2 to lift a preferably disc-type delivery valve 3 against the action of a spring 4 from whence the fuel charge passes by conventional means to an injector (not shown).

3,349586fi Patented Sept. 12, 1967 The lift of the delivery valve 3 is limited by an adjustv able stop means which may be a nut 5 with a locknut 8 screwed on a threaded portion of the stem 6 of an unloading valve, preferably a poppet valve 7 having a seat and fiow area of smaller dimensions than has the delivery valve 3, since it has to deal with comparatively small flows. The stem 6 acts as a guide for the delivery valve 3. One end of the spring 4 presses against the nut 5, and the other end presses on the back of the valve 3. It will be appreciated that the amount of lift is the same for both valves, being that indicated by the dimension 10 as being the play possible between valve 3 and nut 5; and that any adjustment of the nut 5 and its locknut 8 is effective for both valves equally.

The amount of lift is very small, facilitating extremely rapid opening, and this is one factor in determining the magnitude of the residual pressure which it is desired to leave in the system between the delivery valve and the injector. The other factor is the strength of the spring 4, which is also common to both valves.

Return flow passages 9 by-pass the delivery valve, and lead to an annulus around the stem of the unloading valve 7. When the valve 7 is open, the return flow passes to the spill port (not shown) of pump 1.

It will be observed that the seating of the unloading valve 7 is part of the main body of the valve and that it is therefore comparatively rigid; also, that the seating for the delivery valve 3 is similarly a part of the main body. There are advantages in such an arrangement and these are referred to below. In a particular arrangement shown, the whole valve assembly is mounted on a single block that can be rigidly fixed to the pump and the valves can be readily jpre-adjusted as a unit.

Describing now a cycle of operation: both of the valves are closed by the spring 4. A fuel charge from the pump 1 lifts the delivery valve 3 as already described, the valve 7 being kept on its seat both by spring pressure and by the pressure of the body of the valve 3 against the nut 5. When pump spill occurs, the delivery valve 3 closes rapidly under the influence of the spring 4 and the high pressure on the injector side; the very small amount of valve lift also contributes to the rapidity of closure. The unloading valve 7 will open almost instantaneously after closure of the valve 3, overcoming the force of the spring 4, and relieving the pressure on the injector side through the passages 9; the flow passing the seat of the valve 7 to the spill port of pump 1.

Pressure unloading will continue until the spring force overcomes the fuel pressure in the system on the injector side, when the unloading valve 7 closes, leaving a predetermined residual pressure on the injector side of the system.

The embodiment of the invention shown in FIGURE 1 has among its salient features that the delivery valve is disc-shaped and that the unloading valve has a mitre seating and has a stem concentric with the disc-shaped delivery valve and serving as a guide therefor. Both valves share a common spring and have a common lift dimension. From a study of that form of the invention it has come to be realised that the last-mentioned feature puts some limitation on a designer and that if the spring force is correct and the lift is correct as regards the unloading valve, then the spring force in some embodiments may be too great and the lift too small as regards the delivery valve. The discrepancy can cause an excessive pressure drop across the delivery valve seat, and at the same time cause a higher pressure to obtain in the pump space than in the fuel pipe. On the other hand, if the designer measures the correctness of the spring force and the lift by reference to the delivery valve, choosing a weaker spring and a larger valve lift, then over-unloading can occur with its attendant faults of void formation, and loss of pump output. Accordingly, the embodiments of the invention shown in FIGURES 2 and 3 have been evolved, seeking to avoid those design limitations while retraining the advantages that pertain to the embodiment of FIG- URE 1.

In FIGURE 2, the

elements

2, 3, 4, 5, 6, 7, 8 and 9 are given the same reference as are used for the recognizably corresponding elements in FIGURE 1.

On coming to compare the two constructions, that of FIGURE 2 with that of FIGURE 1, we see that as before, the two valves, the delivery valve and the unloading valve, have a common spring 4 in both embodiments. On the other hand, the main difference between FIGURES 1 and 2 is that whereas in FIGURE 1 there is the common valve lift 10, in FIGURE 2 the delivery valve lift 11 is that provided by the play between elements 3 and as before, while the unloading valve lift 12 is that provided between valve 7 and a fixed part 13. Thus the lift dimension of the unloading valve is small while that of the delivery valve is large.

FIGURE 3 shows an embodiment of the invention in which not only are the valve lifts distinct as in FIGURE 2, but each of the valves has its own spring. Although, of course, there are similarities between the construction in FIGURE 3 and those in FIGURES 1 and 2, the convenience of identity of referencing applies only to

elements

3, 5, 6 and 8.

In FIGURE 3, the delivery fiow is through passages 14 and 15 and past the delivery valve 16 itself to the upper space as indicated by arrow 17. This delivery valve 16 has its individual spring 18. Again the spill flow is downwardly as indicated by arrow 19, through passages 20 and 21, past the unloading valve 22, and back through passage 14. The unloading valve 22 has its individual spring 23.

Thus the construction shown in FIGURE 3 differs from that of FIGURE 1 (but is like that of FIGURE 2) in that in FIGURE 3 the delivery valve 16 has its individual lift 24, and the unloading valve 22 has its lift 25 determined by fixed part 26; and it differs from both FIGURE 1 and FIGURE 2 in that each valve 16 and 22 has its own spring 18 and 23. Thus the designer will be able to fit a weak spring for the delivery valve and a strong spring for the unloading valve, having a full freedom of choice.

It will thus be seen that in all three embodiments of the invention that have been illustrated, the unloading valve seats in a fixed part of the assembly and has a stem 6 whereon slides the part 3 which constitutes the closure member of the delivery valve. Also it will be noted as common to all three embodiments, that the seating for both valves is in a fixed part of the assembly: although the design in all cases shows one valve within the other in the sense that one closure member slides on the stem of the other closure member, it does not adopt as in known arrangements the obvious expedient of having one seating on the other, an expedient which is disadvantageous in that, should one valve be returned to its seat smartly, the other valve may be dynamically affected, even to the extent of a partial opening. Furthermore, in all three embodiments, the valves are of a firmly shut-off type not liable to dribble; and moreover, they have their seatings on the same, common, solid part.

In the description of FIGURE 1 it was said that the lift was adjustable, the lift being common to both valves; and this same adjustability (of element 5) appears in FIGURES 2 and 3. In those FIGURES 2 and 3 one may also readily provide for adjustability of lift for the unloading valve-the

elements

13 and 26 described as fixed parts being in the form of plugs screwed or otherwise adjustably fixed into the valve housing. The embodiments of the invention shown in FIGURES 2 and 3 show this interesting and valuable feature in respect of the lift stops, namely that a Violent impact of one valve upon its stop will not cause an opening of the other valve, indeed in the case of the FIGURE 1 embodiment as well as the others,

if the valve impinges violently on its stop the only effect can be to force the unloading valve more firmly onto its seating.

What We claim is:

1. A fuel injection control valve assembly for connection between the pump and the injector of a compression ignition internal combustion engine comprising in combination:

a unitary valve body including at least two fluid passageways therethrough, said passageways terminating in a pair of axially spaced oppositely facing coaxial valve seats;

a first fluid pressure actuated valve member for controlling the admission of fuel from the pump to the injector, said valve member being normally biased to sealing engagement with one of said seats;

a second fluid pressure actuated valve member for controlling the flow of fuel back from the injector to a spill space, said second valve member being normally biased into sealing engagement with the other of said seats;

said second valve member including an elongated stem portion and said first valve member being slidably mounted on said stem.

2. A control valve assembly as defined by claim 1 including a single spring means surrounding said elongated stem and biasing both said valve members toward their respective seats.

3. A control valve assembly as defined by claim 1 including a first spring means surrounding said elongated stem and biasing both said valve members toward their respective seats and a second spring means spaced axially from said first spring means and biasing said second valve member toward its seat.

4. A control valve assembly as defined by claim 3 including means for individually adjusting the lift of said valve members.

5. A control valve assembly as defined by claim 1 in which said valves have a common lift dimension.

6. A fuel injection control valve assembly for connection between the pump and the injector of a compression ignition internal combustion engine comprising in combination:

an extension on the pump barrel at the end of the pump cylinder;

pump delivery passage means through said extension and opening in the upper and lower faces thereof;

bypass passage means through said extension and opening in the upper and lower faces thereof;

valve guide means defined by a bore through the extension;

a first valve member normally closing said bypass passage and having a stem slidably engaged in said bore;

a second valve member normally closing said delivery passage and being slidably mounted on said stem;

means limiting relative movement between said valve members; and

spring means surrounding said stern for urging said valve members in opposite directions to close said passages.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 11/ 1936 Sweden.

LAURENCE M. GOODRIDGE, Primary Examiner.

Claims

1. A FUEL INJECTION CONTROL VALVE ASSEMBLY FOR CONNECTION BETWEEN THE PUMP AND THE INJECTOR OF A COMPRESSION IGNITION INTERNAL COMBUSTION ENGINE COMPRISING IN COMBUSTION: A UNITARY VALVE BODY INCLUDING AT LEAST TWO FLUID PASSAGEWAYS THERETHROUGH, SAID PASSAGEWAYS TERMINATING IN A PAIR OF AXIALLY SPACED OPPOSITELY FACING COAXIAL VALVE SEATS; A FIRST FLUID PRESSURE ACTUATED VALVE MEMBER FOR CONTROLLING THE ADMISSION OF FUEL FROM THE PUMP TO THE INJECTOR, SAID VALVE MEMBER BEING NORMALLY BIASED TO SEALING ENGAGEMENT WITH ONE OF SAID SEATS;