US2214364A - Valve for fuel injection pumps - Google Patents

Description

Sept 10. 1940. vH. C. EDWARDS 2,214,364

VALVE FOR FUEL INJECTION PUMPS Filed Dec. 1s. 193:1 2 sheets-sheet 2 Parenteel Sept. 1o, 194e UNITED STATESv PATENT OFFICE 2,214,364 VALVE Foa FUEL mmcnon Puurs Application December 16, 1937,*Serial No 180,122

6Claims.

This invention relates to a valve for pumps l for the fuel injection systems of compression ignition engines, particularly pumps of the type that terminate the delivery of fuel to the injection nozzle by relieving the pressure in the pump chamber during the pressure stroke'of the piston. The principal object of the present invention is to devise a delivery valve for the above type of pump which upon relief of the pressure in the pump chamber, will permit a return flow thereto of fuel in the conduit leading to the injection nozzle, thereby relieving the pressure in said conduit and thus preventing leakage or dribble of fuel from said nozzle. Other objects are simplicity and cheapness of construction and compactness of design. `'I'he invention consists in the construction, combinations and arrangements of parts hereinafter described and claimed.

In the accompanying drawings, which form part of this specification, and wherein like symbols refer to like parts wherever they occur,

Fig. 1 is a central longitudinal section through a fuel injection pump provided with a delivery valve embodying my invention,

Fig. 2 is an enlarged central longitudinal section through said pump in the region of the discharge valve;

Fig. 3 is a section similar to Fig. 2 illustrating a modification of the invention; and Figs. 4 and 5 are views similarto Figs. 1 and 2, respectively, illustrating a further modication of the invention.

In. the accompanying drawings, my invention is shown in connection with a pump of the kind used for supplying .fuel to the injection nozzle of' aninternal combustion engine of thev comxpression ignition type. 'l'.he upper portion of the pump body or housing l has a vertical bore therein in which is mounted a cylinder 2 having a head portion 3 supported on an annular seat 4 provided therefor in said bore. The pump cylinder 2 is held down on its seat in the pump housing bore by an outlet fitting 5 that is threaded into the upper end of said bore and has its upper end threaded for connection with a suitable conduit or pipe (not shown) which leads to a hydraulically operated fuel injection nozzle (not shown) for delivering fuel to the combustion chamber of the engine.' 'l'.'he outlet fitting 5 is provided near its lower end with a peripheral groove 6 adapted to receive and support a com'- pressible gasket 1 that is held under compression between said groove and the wall of the housing bore and prevents leakage of primary fuel past said fitting.

Mounted for 'reciprocating .movement in the pump cylinder or barrel 2 is a piston 8 which cooperates with said cylinder to form a pressure space or chamber 3 therein at the upper end thereof. vThe pump cylinder y2 has a radial fuel I l port l therein adapted to establish communica- V tion between the pressure space 9 and ar fuel chamber or passageway I I in the pump housing; and the piston 8 is provided with an annular groove I2 which communicates with said presl0 sure space through a longitudinal peripheral groove i3 in said'piston.

Clamped between the outer marginal portions of the opposing end faces ofthe pump cylinder 2 and the outlet fitting 5 is an annular spacer Il or washer I4. Located in the opening in the washer Il is a discharge .valve l preferably in the form of a exible or resilient disk of metal or other suitable material, which is of smaller diameter than said opening so as to provide an annular space or passageway i6 for fuelbetween said washer and said disk. This disk has a relatively thick rim or marginal portion I1, which seats on the upper end of the cylinder 2, and a relatively thin middle or body portion I8' that 25 covers the upper end of the piston receiving bore in the cylinder 2 and forms the top wall of the pressure space l and is provided with a central circular fuel opening or port I9 adapted to be closed by the adjacent end of the outlet tting 5. so

The valve opposing end of the outlet fitting 5 has an annular groove therein which limits the contact between said end of said fitting and the valve l5 to the ported central portion of the latter and also forms an annular fuel passageway or chamber 2l above said valve that communi-A cates at its outer margin'with the annular fuel passageway It between said valve and the spacing washer I4. The outlet fitting 5 is also provided with a fuel passageway 2l which leads from 40 the annular chamber 20 to the outer end of said fitting and communicates with and constitutes a part of the supply pipe or conduit for the injection nozzle of the fuel injection system. The

spacing washer IA is preferably made slightly thinner than the rim portion I1 of the disch:- :ge

valve, whereby the ported-central portion a of said valve is dished or bowed downwardly by the middle portion of the outlet fitting I and is placed under tension sumcient to remain in contact with said tting and keep the port I9 closed during thesuction stroke of the piston.

The modified construction shown in Fig. 3 is similar to that shown in Fig. 2, except that the resilient discharge valve of Fig. 3 is made up of a plurality of superimposed disks I5a of resilient metal and is supported clear of the upper stroke'of the plunger, the central portion I8 of the discharge valve I5 is pressed tightly against the outlet fitting 5, thereby preventing escape of fuel through the port I9 in said valve, while the rim portion I1 of said valve is lifted olf its seat on the upper end of the cylinder, thereby permitting the fuel to pass through the annular space I6 between said rim and the spacing washer Il and thence into the annular chamber 20 above said valve and thence through the longitudinal passageway 2l leading to the fuel injection nozzie. At a. predetermined point in the pressure stroke of the piston, the annular groove I2 therein is placed in communication with the port I in the cylinder, thereby relieving the pressure in the pump chamber and on the rim portion I'I of the valve, which portion is then forced down on its seat on said cylinder by the greater pressure in the annular chamber 20. This higher pressure of the fuel in the annular chamber and the conduit leading to the closed injection nozzle then operates to force the resilient middle portion I8 of the discharge valve downwardly oiI its seat on the inner end of the outlet fitting, thereby permitting a return flow of fuel from said conduit through the central port I9 in said valve into the pressure space of the cylinder. 'I'his return flow of the fuel reduces the pressure of the fuel in the delivery conduit to a pressure that will enable the injection nozzle to close quickly and tightly and thus prevent dripping or dribbling of fuel therefrom and thereby elimi-l nate preignition or after burning of the fuel in the combustion chamber of the engine.

In the modification shown in Figs. 4 and 5, the outlet fitting 5a has an axial fuel passageway 2Ia, threads that terminate Yshort of the outer end of the housing bore and a peripheral groove 6a located outwardly of its threads and adapted to receive a compressible gasket 1a. This location of the gasket 1a. outwardly of the threaded portion of the housing bore makes it unnecessary to force the gasket through the threaded portion o'f the bore and thus prevents the gasket from being torn or frayed by said threads.

The discharge valve I5c shown in Figs. 4 and 5 is supported in an annular casing located in I the housing bore between the pumpv cylinder 2 and the outlet fitting 5a. 'I'his casing comprises a rim portion 22, which is clamped between the outlet fitting and the cylinder, and a hub portion 23, which is connected to said rim portion 'by a radial web having openings 2l therein.- The valve I5c, which is preferably made up of a series of superimposed disks of resilient metal, has its central portion seated on the upper or outer end of the hub portion 23 of the annular valve casing and provided with a central port I9a of smaller diameter than the diameterof said hub portion.v

The valve Ais loosely secured to the valve casing by means of a headed pin 25, which extends through the port I9a with an annular clearance space therebetween and is threaded or otherwise setion 23. The valve is of smaller diameter than the inner diameter of the rim portion 22 of the valve casing so as to provide an annular space therebetween; and the marginal portion of said valve is adapted to seat flatwise against the lower or inner end of the outlet'fitting 5a around the adjacent epd of the fuel passageway 2Ia` therein.

The operation of the modified valve construction shown in Figs. 4 and 5 is as follows: 'Ihe fuel drawn into thevpressure space or chamber 9 during the suction stroke of the piston 8 is placed under pressure when said piston during its pressure stroke passes the port I0. During this pressure stroke of the plunger, the pressure of the fuel against the underside of the valve lifts the ported central portion thereof oil' its seat on the upper end of the hub .portion 23 of the valve casing, thereby permitting the fuel to pass through the axial port IBa in said valve and thence into the axial fuel passageway 2Ia in the outlet tting. When the annular groove I2 in the piston registers -with the port III in the cylinder, the pressure of the fuel on the underside of the valve is relieved and the higher pressure of the fuel in the fuel passageway 2 Ia on the upper surface of the valve then operates to force the marginal portion of said valve off its seat at the inner end of the outlet fitting, thereby permitting a return flow of fuel from said yfuel passageway into the pressure chamber of the cylinder. This return flow of the fuel reduces the pressure of the fuel in the delivery conduit, thereby enabling the hydraulically opened injection nozzle supplied thereby to close quickly and tightly and thus prevent dripping or dribbling of fuel therefrom.

Obviously, the hereinbefore described construction admits of considerable modification without departing from the invention. Therefore, -I do not wish to be limited to the precise constructions shown and described.

What I claim is:

[1. A valve construction comprising an inlet chamber, an outlet chamber, valve seats associated with the adjacent ends of said chambers, the inlet chamber valve seat facing the outlet chamber and the outlet chamber valve seat facing the inlet chamber, and a disk valve interposed between said endsof said chambers and having a central ported portion, `the marginal portion of one face of said valve and the central ported portion of the opposite face thereof being adapted to seat simultaneously on said inlet and outlet chamber, respectively, to cut olf communication therebetween, said valve beingy flexible whereby one of said marginal and central ported portions of said valve is adapted to be forced off its seat by a pressure in said inlet chamber, in excess of that in said outlet chamber, and

the other of said portions is adapted to be forced:A

pff its seat by a. pressure in said outlet chamber greater than the pressure in said inlet chamber.

2. A valve construction comprising an inlet chamber, an outlet chamber, valve seats associated withthe adjacent ends of said chambers, the inlet chamber valve seat facing the outlet chamber and the outlet chamber valve seat facingthe inlet chamber, and a. disk valve interposed between said ends of said chambers and havingA a central ported portion', the marginal portion of one face of said valve and the central ported portion of the opposite face thereof being adapted to seat simultaneously one on said inlet chamber and the other on said outlet chamber to cut olI communication therebetween, said valve cured to the upper or outer end of the hub por being flexible whereby one of said marginal and u ciated with the adjacent ends ofv said chambers,

the inlet chamber valve seat facing the outlet chamber and the outlet chamber valve seat facing the inlet chamber, and a disk valve interposed between said ends of said chambers and having a central ported portion, the marginal' portion of one face of said valve and the central ported portion of the opposite face thereof being adapted to seat simultaneously one on said inlet chamber and the other on said outlet chamber to cut olf communication therebetween, said valve being flexible whereby said marginal portion of said valve is adapted to be forcedoi its seat by a pressure in said inlet chamber in excess of that in said outlet chamber, and said centra-l ported portion is adapted to be forced oi its seat by a pressure in said outlet chamber greater than .the pressure in said inlet chamber.

4. A valve construction comprising an inlet chamber, an outlet chamber, valve seats associated with the adjacent ends of said chambers, the inlet chamber valve seat facing the outlet chamber and the outlet chamber valve seat facing the inlet chamber, and a disk valve interposed between said ends of said chambers and having'a central ported portion, the marginal portion of one face of said valve and the central ported portion of the opposite face thereof being adapted to seat simultaneously one. on said inlet chamber and the other on said outlet chamber to cut off communication therebetween, said valve being flexible whereby said central ported portion of said valve is adapted to be forced .o its seat by a pressure in said inlet chamber in excess of that in said outlet chamber, and said marginal portion is adapted to be forced off its seat by a pressure in said outlet chamber greater than the pressure in said inlet chamber.

5. A valve construction comprising an inlet 'posed between said ends of said chambers and having a central ported portion, the marginal portion of one face Vof said valve and the central ported portion of the opposite face thereof being adapted to seat simultaneously one on said inlet chamber and the other on said outlet chamber to cut off communication therebetween, said valve comprising a plurality of superimposed disks having registering openings forming said central ported portion of said valve, said disks being flexible whereby one of said marginal and central ported portions of said valve is adapted to be` forced oi its seat by a pressure in said inlet chamber in excess of that in said outlet chamber, and the other of said portions is adapted to be forced off its seat by a pressure in said outlet chamber greater than the pressure in said inlet chamber. p

-6. A valve construction comprising an inlet chamber, an outlet chamber, valve seats associated with the adjacent ends of said chambers, the inlet chamber valve seat facing the outlet chamber and the outlet chamber valve seat facing the inlet chamber, a disk valve interposed between said ends of said chambers and having a central ported portion, the marginal portion of' 'one face of said valve and the central ported portion of the opposite face thereof being adapted to seat simultaneously on said 'outlet and inlet chamber, respectively, to cut oi ycommunication therebetween and means for loosely securing said central ported'portion o! said valve to the valve seat for said central ported portion, said valve being flexible whereby the loosely secured central ported portion of said'- valve is adapted yto be forced off its seat by a pressure invsaid inlet chamber in excess of that in said outlet chamber, and said marginal portion of said valve is adapted to be forced oi! its seat by a pressure in said outlet chamber greater than the pressure in said inlet chamber.

HERBERT C. EDWARDS.

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