US2731917A

US2731917A - evans

Info

Publication number: US2731917A
Authority: US
Publication date: 1956-01-24
Anticipated expiration: 1973-01-24

Description

Jan. 24. 1956 F- M. EVANS LIQUID FUEL PUMPS 2 Sheets-Sheet 1 Filed Jan. 21, 1955 Ire/ u ezzfol Jan. 24, 1956 EVANS 2,731,917

LIQUID FUEL PUMPS Filed Jan. 21, 1953 2 Sheets-Sheet 2 United States mnto LIQUID FUEL PUMPS Fraser Mackie Evans, Acton, London, England, assignor to C. A. V. Limited, Acton, London, England Application January 21, 1953, Serial No. 332,302 Claims priority, application Great Britain January 25, 1952 4 Claims. (Cl. 103-41) This invention relates to variable-delivery liquid fuel pumps for internal combustion engines, of the kind in which a reciprocatory plunger has mounted on it a slidably adjustable sleeve for controlling a spill passage in the plunger.

According to the present invention there is provided in association with the plunger, a spill chamber, a sleeve slidable on the plunger for controlling communication between the spill passage in the plunger and the spill chamber, and a spring-loaded axially movable and rotatable control member, axial movement of this member in response to the pressure of the liquid in the spill chamber serving to move the sleeve relatively to the plunger, and angular movement of the said member by manuallyoperable means, serving to vary the elfective area of the outlet from the spill chamber.

In the accompanying drawings:

Figure 1 is a sectional side elevation of a pump embodying the invention, and Figure 2 is a cross section on the line 2.2, Figure 1.

Figure 3 is a perspective view of the control member, this being drawn to a larger scale than in Figure 1.

Figure 4 is a fragmentary sectional side elevation illustrating a modification of .the construction shown in Figure 1.

Referring to Figures 1-3, there is provided in the body a of the pump, a spill chamber b through which extends the pump plunger 0. On the part of the plunger in the spill chamber is slidably mounted a sleeve d adapted to control the spill passage 2 in the plunger, movement of the sleeve relatively to the plunger serving to determine the instant in the wor 'ng stroke of the plunger at which the working chamber 1 at one end of the plunger is put into communication with the spill chamber for limiting the quantity of liquid fuel discharged to the engine. If desired the sleeve may be provided with a valve g loaded by a spring h, through which liquid from the plunger bore e can pass to the spill chamber.

Liquid fuel is supplied to the working chamber 7 through ports i communicating with an annular feed chamber j, the latter being supplied by a feed pipe k. Discharge of the fuel to the engine is effected through a valve in loaded by a spring n.

In one side of the sleeve d is formed a cylindrical hole the axis of which is inclined to the axis of the plunger, and in this hole is contained a spherically formed end part p of a slidable and rotatable control member q which is loaded by a spring r, the axis of this member being at right angles to the plunger c. The control member serves both as a sleeve-actuator and as a throttle, its axial movement serving to slide the sleeve along the plunger, and its angular movement serving to vary the effective area of the outlet from the spill chamber.

The portion q of the control member remote from the sleeve d is of cylindrical form and is accommodated in a cylindrical guide s in the body part. One end of this portion of the control member is exposed to the spill chamber,

so that the control member can be moved against the action of the associated spring by the pressure of the liquid in the spill chamber for advancing the instant of opening of the spill passage e, movement in the opposite direction being effected by the spring. In the guide s is formed a channel 2 which serves as the outlet of the spill chamber,

and in the adjacent part of the control member is formed a recess 11 (Figures 2 and 3) such that by rotation of the control member the effective area of the entrance to the channel 2. can be varied. If desired one edge v of the said recess u may be shaped as, for example, shown in Figure 3, so that axial movement of the control member can also serve to vary the effective area of the entrance to the channel I.

The desired angular movement to the control member is effected by a coaxially arranged hollow and angularly movable cylindrical member w to which the control member is connected by a pin x engaging a slot y in the member w. The said member w (hereinafter referred to as the actuating member) is movable both axially and angularly, and is contained in a housing 2 formed on or secured to the body a of the pump. At its outer end it is provided with a manually operable lever 3 which is movable between appropriately arranged stops 4. The actuating member contains the spring r of the control member, and is itself held in endwise contact with an adjustable stop 5 by a spring 6 arranged around the actuating member, this stop serving to determine the normal maximum fuelsupply position of the control member. To enable a temporary increase of fuel supply to be obtained in excess of the normal maximum when starting the engine that actuating member is moved axially. The effect of this movement enables the spring r to move the control member to the left of the position shown in Figure 1, and so cause an upward movement to be given to the sleeve d, thereby increasing the distance of the outlet end of the spill passage 2 from the valve g.

The plunger 0 of the pump is reciprocated in the usual manner by the alternate actions thereon of a rotary cam 7 and a spring 8. For providing the normal maximum supply of fuel, the sleeve d occupies the position shown in Figure 1. Towards the end of the discharge stroke of the plunger, the outlet end of the spill passage e in the plunger, coincides with the position of the valve g in the sleeve d, and so allows the remainder of the fuel in the working chamber of the pump to be discharged to the spill chamber b. The fuel accumulated in this chamber passes to a drain pipe 9 attached to the part 2 at a rate determined by the setting of the control member q. So long as the pump is operating at a relatively moderate rate the pressure of the fuel in the spill chamber has no effect on the control member. But when the rate of working of the pump exceeds a predetermined amount for a given setting of the control member (which is manually variable by the lever 3), the fuel pressure in the spill chamber rises sufliciently to overcome the action of the spring r, and the control member is moved to the right by the fuel pressure in the spill chamber, thereby causing the end part p of the control member to impart a downward movement to the sleeve d. This results in the spillage from the working chamber to occur at an earlier instant during the discharge stroke of the plunger c and reduces by the desired amount the quantity of fuel discharged to the engine.

In Figure 4 there is illustrated a modification of the con struction shown in Figure 1, for enabling the extra fuel temporarily required when starting the engine, to be obtained automatically. In the right hand of the control member q is formed a transverse slot 10 across which extends a pin 11. The pin is loaded by a light spring 12 carried by the control member, and the outer ends of the pin engage slots y in the actuating member w. Also the said ends are loaded by the spring 13. When the pump is at rest the various parts occupy the relative positions shown in Figure 4, and this condition remains so long as the fuel pressure in the spill chamber is zero, or remains sufficiently low to have .no eifect on'the spring 12. In this condition the sleeve d occupies its uppermost position, wherein it allows a temporary excess of fuel to be supplied to the engine. But with increasing speed the pressure in the spill chamber overcomes the .action of the spring .12 and moves the control member-until the closed end of the slot 10 abuts against the pin 11, so causing the sleeve :1 to be moved to its normal maximum supply position. Thereafter the control member operates in the manner abovedescribed.

In the arrangement shown in Figure 4, the stop 5 shown in Figure l is :not used. Instead the outer end of the actuating member w has a .slida'ble connection with the lever 3, and the normal maximum supply position is determined by an vadjustable nut '14 mounted on the outer end of the said member and arranged to abut against the outer .faceofthe lever under the action of the spring 6.

Whilst in the foregoing there is described an application of the invention .to a pump in which the plunger operates only with a reciprocatory motion, the invention is applicable in like manner to a pump in which the plunger receives both a reciprocatory and a rotary motion, the reciprocatory motion serving to-effect the required pumping action, and the rotary motion serving to connect a delivery passage in the plunger with each in turn of a number of delivery passages in the pump body, the latter being connected to the dilferent cylinders of a multi-cylinder engine.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A liquid fuel pump of the kind specified, comprising in combination a body having therein a spill chamber provided with an outlet, a reciprocatory plunger extending through said spill chamber and having a spill passage therein, a sleeve slidable on said plunger for controlling communication between said spill passage and chamber,

and a spring-loaded axially movable and rotatable control member engaging said sleeve and cooperating with said outlet so that axial movement of said control member serves to move said sleeve relatively to said plunger, and angular movement of said control member serves to vary the effective area of said outlet.

2. A liquid fuel pump according to claim 1, in which the axis of the control member is at right angles to the axis of the plunger, and in which the sleeve is formed with an inclined hole, one end of said control member being situated in :said hole, and serving to co-operate therewith for imparting axial movement to said sleeve in response to axial movement of said control member.

3. A liquid fuel pump according to claim 1, and having in combination with the sleeve-actuating control member which is movable axially by fuel pressure in the spill chamber, a guide provided with the spill-chamber outlet, and a manually operable angularly and axially movable actuating member operatively connected to said control member sothat the latter is capable of a limited amount of axial movement relatively to said actuating member.

4. A liquid fuel pump according to claim 1, having in combination with the sleeve-actuating control member which is movable axially by fuel pressure in the spill chamber, a guide provided with the spill-chamber outlet, and a manually operable angularly and axially movable actuating member having a spring-loaded connection with the control member so that the latter is capable of a limited amount of axial movement relatively to said actuating member which serves also, through the medium of said connection, to determine normal and temporary maximum fuel supply positions of the sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 966,046 Noonan Aug. 2, 1910 1,877,803 Brown et al Sept. 20, 1932 2,282,562 Cole May 12, 1942