US1579458A - Relief mechanism for fuel pumps - Google Patents

Description

Patented Apr. 6, 1926. I UNITED STATES PATENT OFFICE;

PHILIP LANE SCOTT, OF SYRACUSE NEW YORK, ASSIGNOR TO SUPER-DIESEL TRACTOR CORPORATION, OF LA PORTE, INDIANA, 'A CORPORATION OF NEW YORK. I

' RELIEF MECHANISM FOR FUEL PUMPS.

Application filed June18, 1918. Serial No. 240,707.

. To all whom it may concern: vention will appear more clearly from a desame.

Be it known that I, PHILIP LANE Soorr, scription of certainpreferred embodiments a citizen of the United States, residing at thereof as shown in the accompanying draw- Syracuse, in the county of Onondaga and ings in'which Figure 1 represents, chiefly State of New York, have invented certain in section, a fuel pump provided with one 60 new anzl useful Improvements in Relief form of relief valve; Fig. 2 is a portion Mechanism for Fuel Pumps; and I do herof the fuel pump of Fig. 1 showing a modiby declare'the following to be a full, clear, tied form of relief mechanism, and Fig. 3 and exact description of the invention, such 18 a sectional view ofa somewhat different as will enable others skilled in the art to arrangement of the elements of the pump 55 which it appertains to make and 'usethe and a-diiferent form of relief valve.

J ;Referring tothe drawings-and particu- This invention relates to improvements in larly Fig. 1, the body of the pump is pumps adapted particularly for injecting provided with recesses on oppositesidesto li id f l at high pressure into the workrece1ve the usual valves. The suction valve ing cylinder of an internal combustion enthrough whlch fuel is drawn into th u p gine, where the fuel is vaporized and then comprises a plug 11 having a valve seat at ignited by the high temperature of a charge 12, and belng held 1n place by an outer plug of air which has previously been admitted 13 which is threaded as at 14 for attachto the cylinder and compressed to a high ment to a pipe leading to the source of fuel 75 degree during the compression stroke of the supply. A W sh r 15 e ween the W0 plugs engine. The liquid fuel is ordinarily supmsures a tlght joint. The valve 16 is li d th h a Spray valve, d ith th normally held against the seat 12 by a spring provide a pump usual types of pumps at present in use, th 17 hearing against a shoulder in the inside rate of injection of the fuel decreases rapidffllc pump casing. 1y toward, the end of the pump stroke, and The discharge valve 18 through which the amount of fuel delivered-is then so small fuel 1s supplied to the cylinder is held that there is a tendency for drops to form against lts seat by a spring 19, the upper i th f l Spray d t th in f th end of which bears against aplug 20 screwed spray valve i t th b ti h mb into the side of the pump casing, and threadf th h d ed as at 21 for attachment. to a pipe lead- It is an object of the present invention to ug o the combustion chamber of. the ensystem h i means f "me. A washer 22 prevents any leakage suddenly relieving the pressure before .too gh t e threads of the plug 20. 00

l t f pumping i r ch d, that Between the two valves is the pump chamthe spray valve shall quickly close and out, ber'23 Within which a plunger 24 is adaptoii any dripping of fuel that might otherd to pr te. The plunger 24 passes i occur t d th d f th p through a bore 1n the'pump casing 10, "and at its outer end carries a roller 25 pressed stroke. 1

In accordance with the present invenagainst aitcam 26 by a Spring 27. The cam ti th i id d on th hi h pree- 26 1s mounted on a shaft 28 which is actusure side of the fuel pump, a relief valve flie om the moving parts of the engine or equivalent ve' nt controlled byand achrough suitable gearing.

'tuated in timed relation to the other mov- The construction thus far described is one ing'parts of the pump, so that as the pump of the usual forms of pumps adapted to plunger eh th df its king supply liquid .fuel at high pressure to the,

stroke the valve will be quickly opened to cylinder of an internal combustion engine, cause a sudden decrease in the pressure of but n 7 n i the p n invention the oil in the passage leading to the spray there s provided on the hi'ghpressure side 05 valve, with the result that the latter will 9f the pump, a relief valve which in Fig. 1 1 be quickly closed and, the supply of fuel is shown as avalve stem 30 slidably mountto the combustion chamber of the engine ined in a borein the pump casing, and 'prostantly cut off to prevent any excess-fuel VldBd with a pomted mner end which fits from dripping through the spray valve. within a conical passageway between the no The particular nature of the pres nt inbore'and the ch ber of the discharge valve 18. The valve stem is slotted as at 31 to permit the passage of liquid through the relief valve. The outer end of the valve stem 30 is provided with a shoulder 32 fitting within a cavity in the pump casing. A spring'33 engages the shoulder 32, and at its other end bears against a block 34 which is slidably mounted in the bore, but prevented from turning therein by a screw 35 having its inner end fitted within a slot on the side of the block. The outer end of the slidable block is engaged by a cam 36 on a shaft 37 which by means of gears 38, 39 and 40 is driven by and in timed relation with the shaft 28, carrying the cam 26 which controls the operation of the pumping plunger 24 In the operation of the mechanism described above, the plunger 24 is operated to draw liquid fuel, through the suction valve 16 on the outward stroke of the plunger, and force it througlr'the discharge valve 18 on the inward stroke of the plunger, it being understood that ,the cam 26 is driven in timed relation from the moving parts of the engine to cause the working stroke of the plunger to be performed at the right instant to force the fuel through a spray valve into the combustion chamber of the engine. I The shaft 37 carrying the cam 36 which controls the slidable block 34 is 'so driven with rela tion to the cam 26 that as the plunger 24 approaches the end of its pumping stroke, the nose of cam 36 will pass 0d of the end of block 34 and thus relieve the force exerted upon the spring 33 so that the force of the latter upon val e stem 30 will not be suf- .ficient to hold the latter against the pressure that exists in the discharge chamber at this time. The relief valve will thus open and relieve the pressure on the discharge side of the pump. In connectiom with a pump of the character described, there is at the cylinder, a spray valve through which liquid fuel is injected into the combustion chamber, and the release of pressure between this valve and the discharge valve 18 will cause the spray valve to be quickly closed, cutting 011 any dripping of fuel into the cylinder. The relief valve 30 will remain open until the nose of cam 36 again engages the end of sliding block 34 to again putthe spring 33 under compression suflicient to hold the relief valve closed against the pressure produced i the chamber of the discharge valve 18 0 next working stroke of the pump plunger. A fuel supply puinpof the general type shown in Fig. 1. may be operated without the discharge valve 18, the spray which controls the admission of fuel into the combustion chamber being used as an equivalent of the discharge valve. In this case the r lief valve may be located atany point beyond the suction valve 16, because it is-then only necessary to relieve the pressure in the systhe.

tem between the suction valve 16 and the spray valve to cause the latter to close quickly to prevent leakage into the combustion chamber. a

Figure 2 shows a modification of the invention in which a plunger 45 is substituted for the valve stem 30 of Figure 1. The plunger 45 is slidably mounted in a bore in the pump casing, but has an oil-tight fit .therein. The outer end of this plunger is its pumping stroke, the nose'of cam 47 passes out of engagement with the head 46, thus permitting the fluid pressure acting upon the inner end of plunger 45 to force the latter outwardly against the compression of spring 50, it being understood that this spring is so adjusted that it will yield under-the pressure existing on the discharge side of the pump, as the pump plunger approaches the limit of its pumping stroke.

Outward motion of plunger 45 will tend to create a vacuum on the discharge side of the pump, which will cause a sudden decrease of pressure in the liquid on this side of the pump, with the result that the spray valve will be closed quickly to prevent any leakage therethrough.

If the plunger shown in Fig. 2 is used instead of the valve 30 of Fig. 1, it is necessary that the discharge valve 18 be eliminated, or if it is retained, means should be provided for holding it open at the beginning of the suction stroke of the pump plunger. If the discharge valve should be left in the pump, the plunger 45, as it is returned to its original p sition by cam 47, would in itself act as a pump and tend to force liquid through the spray valve. If the discharge valve 18 is removed, then the pump chamber 23 and the chamber with which the plunger 45 is associated, are in ated directly-with the pump chamber instead of with a chamber communicating wit lthe latter as 1H the case of Figs. 1 and 2. in Fig. 3 the pump plunger, the inlet valve and the discharge valve are substantially the same as the corresponding parts of Ifig. 1, except that the pump plunger 24 has a tapered end as at 55, and the stem of the discharge valve 18' is provided with a ,screw 56 adapted to be engaged by the plunger 24' as the latter approaches the end of the pumping stroke. In this figure, the relief mechanism comprises a valve-stem 57 slidably mounted in a tubular member 58 inserted in a bore in the pump casing and communicating with the pump chamber'23. The inner end of the valve stem is tapered to fit a correspondingly formed valve seat at the inner end of the tubular member 58. This tubular member is held in place against avwasher, 59 by a plug 60 provided with a bore to receive the enlarged .end 61 of the valve stem, and a spring 62 whic1 bears against this enlarged end, and at its other end is held in place by an adjustable plug 63. The valve stem 57 is provided with one or more longitudinal -,grooves 6 1 to permit the discharge of liquid from the pump chamber-When the valve stem is forced outwardly by engagement of the pump plunger 245 with a screw 65 adjustably mounted in the inner end of valve stem 57.

The force of the spring 62 is such that it holds the valve 57 upon its seat at the inner end of the tubular member 58 against the pressure that exists during the pumping stroke, but when the pump plunger 24: approaches the end (if this stroke, it engages the screw 65 and forces the valve stem 57 outwardly against the-efl'ect of spring 62, thus causing the pressure in the pump chamber to be instantly relievedi At the same time that the inner end of the pump plunger engages the screw 65, the cylindrical part of the plunger will pass under the screw 56 of the discharge valve 18' and hold this valve open while the pressure is being relieved by the opening of the ,relief valve. Were it not for this arrangement, the discharge valve 18 would close as soon as the pressure in the pump chamber was relieved, and leakage of liquid might not be avoided; As soon as the pump plunger begins its suction stroke, it moves out ofengagement with the screws 56 and 65, thus permitting the discharge valve and i the relief valve to close.

I claim:

1. In a fuel injecting system for internal combustion engines having a pump supplying liquid fuel under high pressure to an injection valve to open the valve and force the fuel into the combustion chamber, the combination of a vent between the pump and the injection valve, means for closing said vent during the injection stroke of the pump, and means for releasing said closing means near the end of the injection stroke to permit said vent to be opened to abruptly combination of a vent between through the spray valve the opening into the combustion chamber and cause a sudden closing of the injection valve to prevent dripping of the fuel.

2. In a fuel injecting system for internal combustion engines having a pump supplying liquid "fuel under high pressure to an injection valve to open the valve and force the fuel into the combustion chamber, the the pump and the injectionvalve, a closure for said vent, means for holding said closure in vent-closing position during substantially the entire and means for injection stroke of the pump, releasing said holding means near the end of the injection stroke to permit said closure to open the vent to abruptly diminish the pressureof the liquid fuel'at the opening into the combustion chamber and cause a sudden closing of the injection valve to prevent dripping of the fuel.

3. In a fuel injecting system for internal combustion engines having a pump supplying liquid fuel under high pressure to an injection valve to open the valve and force the fuel into and said injection valve, said vent, means for holding said closing means in vent closing position against the pressure of the fluid between said pum and said injection valve during 'substantialiy' the entire injection stroke of the pump, and means for releasing said holding means to permit the pressure of the fluid to open the vent near the end of the injection stroke to cause an abrupt diminution'vof pressure at the opening into the combustion chamber and produce a sudden closing of the injection valveto prevent dripping of the" fuel.

4. In a fuel injecting system for internal the combustion chamber, the. combination of a vent between said pump means for closing combustion engines having a pump supply ing liquid fuel under high pressure to an injectionvalve to open the valve and force the fuel into the combustion chamber, the combination of a vent on the high pressure side of the pump, means for closing said vent against the fluid pressure produced by said pump, during its injection stroke, and means under the control of said pump for actuatingrsaid vent closing means to open the vent near the end of the injection stroke of said pump to abruptly diminish the pressure of the liquid fuel at the opening into the combustion chamber and cause a sudden closing of the injection valve to prevent dripping of the fue j 5. In a fuel injecting system for internal combustion engines having a pump supplying liquid fuel under high pressure to an injection valve to open thevalve and force the fuel into the combustion chamber, the combination of a vent on the high pressure side of the pump, vent against the fluid pressure produced by said pump during its injection stroke, and means adjustably associated with said closing means and adapted to be engaged by the plunger of the pump for actuating said vent closin means as the plunger approaches the end 0 its injection stroke to abruptly diminish the pressure f the liquid fuel at the opening into the co bustion chamber and of the engine,' the combination of a vent communicating with the conduit, means for closing the vent during the injection stroke of the pump, and means for releasing the closing means near the end of the injection stroke to ermit said vent to be open to abruptly dlminish the pressure of the fuel in the conduit! to cause a sudden closing of the injection valve to prevent dripping of the fuel.

7 In a fuel injection system for internal combustion engines, havin a pump supplying liquid fuel under hig pressure to an injection valve to open the valve and force the fuel into the combustion chamber, the

combination of a vent on the high pressure side of the pump, a closure for said vent a spring for holdin said closure in ventclosing position against the fluid pressure produced by the pump during its injection stroke, and means operable in timed relation with ,thepump for relieving the tension of the spring near the end of themjection stroke of the pump to permit the pressure of the fuel to'act upon the closure to open the vent to cause an abrupt diminution of pressure at the opening into the combustion chamber and produce a sudden closing of 'the injection valve to prevent dripping of the fuel.

In testimony whereof I affix my sign".

ture.

PHILIP LANE SCOTT