US 3416505 A
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Description (OCR text may contain errors)
Dec. 17, 1968 s. F. BARBER 3,416,505
' FLUID CONTROL VALVES Filed Oct. 5, 1966 2 Sheets-Sheet 1 Dec. 17, 1958 v s, BARBER 4 3,416,505
FLUID CONTROL VALVES 2 Sheets-Sheet 2 Filed Oct. 1966 19% V 7 "\bw United States Patent 3,416,505 FLUID CONTROL VALVES Stanley Frederick Barber, Pinner, England, assignor to C.A.V. Limited, London, England, a company of Great Britain Filed Oct. 3, 1966, Ser. No. 583,856 Claims priority, application Great Britain, Oct. 5, 1965,
3 Claims. cl. 123-139 ABSTRACT OF THE DISCLOSURE A fuel pump for delivering fuel in timed relationship with the engine having a fluid source whose pressure can vary in dependence on the engine speed and means responsive to the fluid pressure for varying the timed relationship of the pump with the engine during engine operation. A valve between the fluid source and the pressure responsive means serves to prevent fluid pressure application to the responsive means until the pressure has risen to a predetermined value and thereafter allow pressure application to the responsive means at any value of the pressure above second predetermined value lower than the first predetermined value.
This invention relates to liquid fuel pumps and has for its object to provide such a pump in a simple and convenient form.
In the accompanying drawings:
FIGURE 1 is a sectional side elevation of one example of a liquid fuel pump in accordance with the invention,
FIGURE 2 is a section on the line 22 of FIGURE 1 and FIGURE 3 is a sectional side view of part of the pump shown in full in FIGURES 1 and 2.
Referring to FIGURE 3 there is provided a fluid control valve A which comprises a valve body 1 in which is formed a stepped bore 2. Intermediate the ends of the bore is defined a seating ,3 with which co-operates a valve closure member in the form of a ball 4. Slidably mounted in the wider portion of the bore is an abutment 5 which is loaded in a direction towards the seating by a coiled compression spring 6 and in the abutment bears upon the ball to urge same onto the seating. The spring bears at its end remote from the abutment upon a plug 7 engaged in the wider end of the bore. Moreover, the abutment at its end adjacent the ball is of stepped form and defines with the all of the bore a chamber from which extends an outlet passage 8. Furthermore, the space between the abutment 5 and the plug 7 is vented to a low pressure, by way of a passage 7a.
In use, when fluid at a predetermined pressure is applied to the narrower end of the bore the ball 4 will be moved from the seating to allow fluid to flow into the chamber and through the outlet passage 8. Moreover, when this occurs the pressure of fuel within the chamber will act upon the abutment which has a larger area presented to the pressure than the ball so that until the pressure of fluid falls a predetermined amount below the aforesaid predetermined pressure the ball will not be closed onto the seating.
One example of the pump incorporating the valve is shown in FIGURES 1 and 2 and includes a pair of pumping plungers 10 which are mounted in a part 11 rotatable in synch-ronism with the engine, and a cam 12 for moving the plungers inwardly to discharge fuel to 3,416,505 Patented Dec. 17, 1968 'ice the engine as the part rotates. In order to vary the timing of fuel injection the cam 12 is movable about the axis of rotation of the part 11 and this is effected by a fluid pressure operable and spring loaded piston 13 which is supplied with fuel under pressure from a feed pump 14 mounted within the body of the pump and arranged to deliver fuel at a pressure which varies in a manner dependent upon the speed of the engine. Usually as the engine speed increases the output pressure of the feed pump increases and the cam is moved to advance the timing of injection. For starting purposes it is desirable to have the timing of injection retarded and to maintain this until the engine has accelerated above the normal idling speed but it is desirable that once the engine is running the timing of injection should be advanced even at idling speeds. By locating the valve A described above intermediate the feed pump outlet and the cylinder containing the fluid pressure operable piston 13 the desired result is achieved. When the engine is at rest the fuel pressure is zero and the ball 4 is held against the seating 3 and is not moved therefrom until the engine speed is above the desired idling speed.
The ball 4 serves a further purpose and this is to prevent the reaction of the plungers 10 against the lobe or lobes of the cam moving the cam angularly. When the plungers strikes the lobes the pressure of fuel within the cylinder containing the fluid pressure operable piston increases to a value which is higher than the output pressure of the feed pump with the result that the ball 4 is urged onto the seating 3 thereby preventing fuel leaving the cylinder and thereby locking the cam against move ment. As soon as the plungers are free of the lobes the pressure in the cylinder decreases and the ball is pushed off the seating to permit re-adjustment of the cam if the output pressure of the feed pump has varied.
Conveniently the valve body 1 is screw threaded at its end remote from the plug whereby it can serve to secure parts of the pump together.
Having thus described my invention what I claim as new and desire to secure by Letters Patent is:
l. A liquid fuel pump for supplyingfuel to an internal combustion engine and comprising a-plunger part and a cam part, one of said parts being driven relative to the other part to effect movement of the plunger part to deliver fuel to the engine, a cylinder, a resiliently loaded fluid pressure operable piston for moving the other part to effect variation in the timing of delivery of fuel to the engine mounted in the cylinder, a feed pump having an outlet arranged so that its output pressure varies in accordance with the speed at which the engine is driven, and -valve means interposed between the outlet of the feed pump and the cylinder, the valve means being arranged to prevent the application of fluid pressure to the piston until the engine has accelerated from rest to a predetermined speed above its normal idling speed, but to allow the application of fluid pressure from the feed pump to the piston thereafter at all speeds down to idling speed, said valve means comprising a body having a stepped bore, a seating defined within the bore, a resiliently loaded abutment slidable within the wider portion of the bore and arranged to be urged towards said seating a valve closure member interposed between the seating and the abutment, the narrower portion of the bore being in communication with the outlet of the feed pump, and the wider portion of the bore being in communication with said cylinder, with the area of the closure member exposed to the pressure in the narrower portion of the bore when the valve is closed being less than the 3 4 area of the abutment which is exposed to the pressure in References Cited the bOrC When the valve is Open. P
2. The liquid fuel pump as claimed in claim 1 in which the closure member is in the form of a ball which 2,660,992 12/1953 Roosa 123' 139'13 i urged upon the seating when the fluid pressure in the 5 2,910,975 11/1959 Evans 123139'13 wider end of the bore exceeds the pressure in the nar- 3051154 8/1962 Kemp 123139l3 3,116,728 1/1964 Evans l23l39.13
rower end of the bore.
3. The liquid fuel pump as claimed in claim 2 in which the wider end of the bore is closed by a plug and the LAURENCE GOODRIDGE Pnmmy Exammer' resilient loading of the abutments is provided by a coiled 10 US. Cl, X.R, compression spring which is disposed between the plug 1032 and the abutment.