US2319566A - Fuel pump - Google Patents

Description

May' `18,"1943 A F. Rf SUNDEMAN ETAL. `25319566 FUEL PUMP Filed May 2, 1941 @m4/ym www@ ATTORNEYS Patented May 18, 1943 FUEL PUMP Frederick R. Sunderman,

New York, and

James McAuley, Bronx, N. Y., assignors to F. S. McLachlan Co. Inc., a corporation of New York Application May 2, 1941, serial No. 391,532

(o1. 12a-14o) 2 Claims.

This invention relates to fuel pumps for internal combustion engines and the like and has for its object the provision of an improved fuel pump of this character. The invention aims to provide a double-acting fuel pump having at least one pair of interconnected reciprocating pistons driven by a suitable crank means, each'piston being arranged to inject a measured quantity of fuel oil from its cylinder into one engine cylinder. It is an Object of the invention to provide a fuel pump having valve means in cooperation with the pump pistons for accurately measuring the amount of oil injected during each stroke of the piston which is simple in construction and positive in operation.

The pistons of the fuel pump of the invention draw in a uniform quantity of oil on each intake stroke, and the amount is ordinarily more than is required for each injection. The amount of oil over that required forthe injection is referred to herein as the excess oil. The pump pistons of the invention have passage means for returning the excess oil in the pump cylinders back into the oil storage system. The excess oil is returned to the oil storage system without in any way interfering with, or altering the action of the pump pistons. The pump pistons reciprocate as a unitary structure and require no adjustments in varying the amount of oil injected during each stroke.

In a preferred and advantageous construction of the invention, each piston is provided with passage means arranged to connect with one of a plurality of ducts in the cylinder through which the excess oil may be returned to the oil storage system. The invention comprises a separate valve means for each pump cylinder having a by-pass for selectively connecting any one of the said ducts to the oil storage system whereby the excess of oil in the pump cylinder is returned to the oil storage system and the amount of oil for each injection is accurately measured.

Each pump cylinder and piston is constructed and arranged to permit a carefully measured quantity of oil which enters the pump cylinder from the oil storage system to be injected into the engine cylinder in a continuous and strong stream. The pump piston travels under such speed and positive action that a strong stream is delivered from the injection nozzle up to the very instant when the stream is out off.

The valve means preferably comprises an oscillatable member having a by-pass in the form of a small hole therethrough in continuous contact with a conduit leading to the cil storage sysem and in adjustable Contact with any selasted one of the ducts. The by-pass in the valve may be placed in coincident engagement with any oneof the ducts which, during each piston stroke, connect with the passageway in the pump piston. The oscillatable valve member may be provided with any suitable means for setting it to place the by-pass in coincident engagement with any selected duct, especially when it is desired to control the pump manually. The fuel pump may also be provided with any suitable governor responsive to the speed of the engine for actuating the oscillatable valve member of each pump simultaneously and automatically.

The pump pistons are arranged in their cylinders so that, at the end of the injection stroke, there is a small quantity of oil left in the cylinder.V In using a crank to reciprocate the pistons,

I' prefer to use a Scottish-yoke and to arrange the crank therewith so that the piston, at the endof its injection stroke, returns relatively very rapidly and thereby cuts oi the oil injection very sharply and prevents oil dribble from the injection valve into the engine cylinder.

One of the important features of the invention is the arrangement of the oil inlet port in the cylinder in such a position with respect to the stroke of the piston that air in the cylinder is forced into the oil storage system, thereby eliminating the necessity of bleeding out the air whenever parts of the pump nozzle or pipes have been repaired or replaced.

These and other novel features of the invention will be better understood after a consideration of the following discussion taken in conjunction with the accompanying drawing, in which:

Fig. 1 is a sectional side view of a fuel pump embodying the invention;

Fig. 2 is a sectional view along the line 2-2 of Fig. 1, and

Fig. 3 is a sectional view along the line 3 3 of Fig. 1.

The fuel pump illustrated in the drawing comprises a pump frame I having two diametrically opposite pump cylinders 2 and 3 in which are reciprocably mounted the pump pistons 4 and 5 respectively. The pistons connect to the Scottish-yoke comprising the yoke member 6 having a slot ,'I in which the crank 8 rotates. As shown in the drawing, the pistons and yoke member are a unitary element. The pistons have passageways IIJ and II extending from the face to the side and the cylinders are provided with a plurality of spaced ducts I2, I3 and I4, and I5, I6 and I'I which connect the cylinders 2 and 3 with the cylindrical openings of the control valves 2|) and 2| respectively.

The control valves have oscillatable valve members 22 and 23 preferably in the form of cylinders having the by- passes 24 and 25 respectively. The valves have oil conduits 26, 2l extending along the sides of the valve members which also extend from an oi1 storage system (not shown) and also connect with the intake ports 28 and 29 of the cylinders.

'I he valve members are connected by eccentrically attached couplings 30 and 3i to an adjustment member 32. The adjustment member has a manually operated lever which slides in contact with an arcuate dial 34 provided with a position-setting lock 35. By swinging the lever 32, the valve members 22 and 23 are each moved the same extent but in opposite directions. By moving the lever to the proper positions, the by-pass may be placed in communicating engagement with any 'one of the ducts.

The pump cylinders have discharge passages 40 and 4| leading to the valves 42 and 43 which are normally held closed by the springs 44 and 45 respectively. The valves control the flow of oil int-o the chambers 45 and 41 and the passages 48 and 49 in the coupling members 50 and 5i which connect to the pipes (not shown) leading to the injection nozzles of the engine. The areas of the valves subjected to oil pressure, and the elasticity of the springs are selected so that a high oil pressure is required to lif-t the valve for each injection. An oil pressure of around 1750 pounds per square inch is ordinarily satisfactory. However, it is obvious that any suitable pressure may be used. The injected oil passes up through the central passages 52 and 53 and is discharged through radial ports 54 and 54a when the valves are raised.

As is best shown in Fig. 3, the shaft 55 which drives the crank 8 is connected to the gear 56 which is connected to and driven by the engine. One end of the shaft carries the centrifugal governor 51 which comprises the weights 58 and 59, and sliding sleeve 60. 'I'he sliding sleeve 60 has an annular groove 6l in which one end of the bell crank 62 is engaged. The other end of the bell crank engages a slot 63 (Fig. 1) in the adjustment member 32. When the adjustment member 32 is locked in position to the dial member 34, the governor is held in an inoperative position, and when the adjustment member is unlocked and free to oscillate, the adjustment member and valves 2li and 2| are under the ccntrol of the governor.

In operating the pump of the invention, the adjustment member 32 may be set in any desired position and secured in that position by locking it to the arcuate member 3Q by the lock 35. The adjustment member is set in such a position that the by- passes 24 and 25 are placed in coincident engagement with one of the ducts, for example ducts I4 and I1. In this -position the pump is set to discharge the minimum quantity of fuel during each injection. As one of the pistons, for example piston 5, moves to the left, the cylinder 3 fills with fuel oil. The piston strokes are such that, at the end of the intake strokes, there is a considerable space between lthe ends of the pistons and the ports 28 and 29. This clearance permits any air which may be in the cylinder to be forced back into the oil storage system.

When the piston 5 starts to move towards the right from the position shown in Fig. 1, a part of the oil and any air which maybe present is forced back through port 2,9 and conduit 21 into the oil storage system. After the piston passes beyond port 29, it then puts such pressure on the oil that the valve 43 is raised against the action of the spring 45 and the oil commences to ow to the injection nozzle of the engine. When the passage II in the piston is coincident with the duct I1, the oil flows through the passage Il, duct I1, the by-pass 25 and into the conduit 21. This is the excess of oil over that required for the injection and the remaining oil in the cylinder 3 is charged through valve 43 and into the injection nozzle.

When it is desired to operate the pump under the control of the speed governor 51, the lock 35 is disengaged leaving Ithe adjustment member 32 to be actuated entirely by the governor. As the speed of the engine increases and the centrifugal weights 58 and 59 are thrown outwardly, the sleeve 60 moves to the left, thus turning the bell crank 62 and moving the valve members 22 and 23 to such positions that their by-passes will con nect with one of the ducts returning a portion of the oil in the cylinders to the oil storage system. When the pump is under the control of the governor, the regulation may be effected entirely by slightly oscillating the valve members to cause the by-ipass and the duct with which it is connectedto act as a throttling orifice. The return of oil is, accordingly, varied by varying the size of the opening under the action of the governor.

The pump unit illustrated in the drawings having one pair of double-acting pistons is a unit suitable for supplying oil to two engine cylinders, the nozzle of each .cylinder being connected by suitable tubing to the couplings 50 and 5I. Any suitable number of such units may be provided and each pair of pistons is preferably driven by the same shaft.

We claim:

l. A fuel pump for internal combustion engines which comprises at least one pair of opposed pistons each reciprocable in its own cylinder, a crank means for driving each piston, an oil passage in each piston, a valve for each piston having an oscillatable valve member, a by-pass in the valve member, a conduit connecting an oil storage system, the valve and the pump cylinder, a plurality of ducts connecting each cylinder with each valve, and means for adjusting the position of the valve member to connect the by-pass with any one of the ducts and with the conduit, whereby the excess of oil over that required for each injection is returned from the cylinder through the passage, duct and the by-pass back to the conduit.

2. A fuel pump for internal combustion engines which comprises at least one pair of opposed pisn tons each reciprocable in its own cylinder, a crank means for driving each piston, an oil passage in each piston. a valve for each piston having an oscillatable valve member, a by-pass in the valve member; a conduit connecting an oil storage system, the valve and the pump cylinder; a plurality of ducts connecting each cylinder with each valve at spaced intervals in the longitudinal direction of the cylinder, said ducts being arranged to effect selective and coincident engagement with the by-ipass by adjustment of the valve member to vary the quantity of oil in each injection, means responsive to the speed of the engine operatively connected to the valve member whereby the valve member is adjusted in accordance with the speed of the engine to throttle the passageway between the duct and the by-pass and thereby varying the supply of fuel to control the speed of the engine.

FREDERICK R. SUNDERMAN. JAMES MCAULEY.

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