US2548640A - Fuel pump - Google Patents

Description

April 10, 1951 H, J, WEL H 2,548,640

FUEL PUMP Filed March 31, 1947 7 3 Sheets-Sheet 1 V INVENTOR.

HARRY J WELCA/ BY 55 5a 57 ATTO/P/WFYS April 10, 1951 J w c 2,548,640

v FUEL PUMP Filed March 3]., 1947 3 Sheets-Sheet 2 H. "I 33 Ilia-i=4 l |3 I 54% 34 i 35 l5 z I as 23 INVENTOR. 1444mm (fWa-zcx-r ATTORNEYS April 10, 1951 WEL 2,548,640

FUEL PUMP Filed March 51, 1947' s Sheets-Sheet s INVENTOR. IZ/A 4w Y J W54 CH Q aiZ/AMJ/W 1 ATTOAIV Y5 Patented Apr. 10, 1951 FUEL PUMP Harry J. Welch, Walled Lake, Mich., assignor to pany, Novi, Mich, a cor- Novi Equipment Com poration of Michigan Application March 31, 1947, Serial No. 738,417 Claims. (01. 10s 154) This invention relates generally to pumps and refers more particularly to improvements in fuel pumps for use in connection with the induction system of internal combustion engines.

In many types of internal combustion engines, it is the practice to draw fuel from a suitable source of supply and to force it into the float chamber of the carburetor by a pump. Pumps employed in the past for the above purpose are usually of the diaphragm type and are operated from the cam shaft of the engine. Although such pumps are used extensively to transfer fuel from the Source to the induction system of an internal combustion engine, they nevertheless, possess numerous shortcomings. In the first place the pump diaphragms are inherently not very durable and failure of the pump may be frequently traced to defective diaphragm performance. In the second place, diaphragm pumps are usualli of fixed capacity and must be replaced by larger or smaller pumps to suit different pressure requirements. Thus in instances where engines having different fuel pump pressure requirements are manufactured or serviced, it is necessary to provide a large inventory of fuel pumps.

One of the objects of this invention is to overcome the above objections by providing a piston type fuel pump wherein the piston is moved on its suction stroke by power means such for example as the cam shaft of an internal combustion engine and wherein a spring is provided for moving the piston on .its pressure stroke. The spring is calibrated in accordance with the pressure requirements at the delivery side of the pump and is readily interchangeable with springs having different strength characteristics. Thus one pump model may be employed to produce different delivery pressures by merely interchanging the springs. Moreover, piston type pumps are inherently more durable than diaphragm operated pumps and, as a result, assure continued service over long periods without attention.

Another feature of this invention is to provide a pump assembly wherein the spring for moving the piston on its pressure stroke is interposed between the piston and a cap readily removably clamped to one end of the pump cylinder for closing the latter end. Thus the spring may be quickly removed and exchanged for another spring by merely detaching the cap from the cylinder.

A further feature of the present invention is to provide a pump assembly having inlet and outlet passages communicating'with the cylinder at one end of the piston and respectively controlled by check valves alternatively movable to their open positions upon movement of the piston in opposite directions in the cylinder.

Still another feature of this invention is to provide a pump assembly having a cup-shaped piston and having a valve carrying body forming with the inner wall of the cylinder .an annular space for slidably receiving the skirt portion of the piston. Actually the opposite sides of the piston skirt respectively slidably engage the inner Wall of the cylinder and the outer wall of the valve carrying body with the result that the piston is effectively supported during operation thereof.

A still further object of this invention is to provide a pump assembly of the type previously set forth composed of a relatively few simple parts capable of being inexpensively manufactured and assembled to form a compact structure.

The foregoing as well as other objects will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein:

Figure 1 is an elevational view of a pump assembly embodying the features of this invention;

Figure 2 is a top plan view of the'pump assembly shown in Figure 1;

Figure 3 is a sectional View taken substantially on the line 3-3 of Figure .2;

Figure 4 is a sectional view taken on the line 4 l of Figure 2;

Figure 5 is a sectional view taken on the line 5-5 of Figure 2;

Figure 6 is a sectional view taken on the line 66 of Figure 2;

Figure '7 is a cross sectional view taken on the line 11 of Figure 3; and

Figure 8 is a sectional view taken on the line 8-8 of Figure 5.

The pump assembl shown in the drawings for the purpose of illustrating this invention comprises a casing Ill, .a body .member II and a .piston I 2. In the interests of manufacture on a production basis, both-the casing and body member may be die cast, although any other suitable method of manufacture may be resorted to without departing from the spirit and scope of this invention.

The casing H3 is formed with a cylinder l3 at the upper end and. is provided with a reduced attaching portion 14 at the lower end. The upper end of the cylinder I3 is open and the lower end is closed by a wall I5 of the reduced portion. The reduced portion I4 is formed with circumferentially spaced bosses l6 and H, respectively, having inlet and outlet ports l8 and i9 therein. The ports respectively communicate with vertical passages 29 and 2i extending upwardly through the wall I5. The wall 15 is cored out between the passages in the manner indicated by the reference character 22 in Figures 3 and 4 of the drawings to reduce the weight of the part to a minimum. It will also be noted from the above figures of the drawings that the portion I4 is provided with diametrically opposed attaching flanges 23 and is centrally bored to enable extending a piston operating rod 24 therethrough. Actually the bore is enlarged in diameter for a substantial distance from the upper end to accommodate a sleeve 25 of wear resisting material and the rod 24 is slidably supported in the sleeve.

The casing i is formed with a radially outwardly extending annular flange 26 at the top of the cylinder l3 and a cap 21 is clamped to the flange 26 to close the open end of the cylinder. As shown in Figure 4 of the drawings, the cap 2'! is frustro-conical in shape having a radially outwardly extending annular flange 23 at the lower end adapted to seat on the flange 2S and having a flat top wall 29. The cap 2'! is removably clamped in place on the cylinder 23 by a bracket comprising a strap 38 extending over the cap 21 and having lugs 3| at the outer ends adapted to engage the underside of the flange 23 at diametrically opposite points. The central portion of the strap is located directly above the flat wall 29 of the cap 2'! and a nut 32 is secured thereto for threadably receiving a thumb screw 33. The lower end of the screw 33 abuts the wall 29 at the center thereof and serves to clamp the flange 28 on the cap against the flange 26. In practice an annular sealing gasket is positioned between the flange 26 on the casing and the flange 23 on the cap to prevent the escape of fluid out of the top of the cylinder.

The body member I l is cylindrical and is seated on the wall I of the casing in concentric relation to the cylinder l3. The diameter of the body II is somewhat less than the internal diameter of the cylinder and cooperates with the latter to provide an annular space 3 3. The central portion of the body is bored in axial alignment with the bore in the casing to permit extending t -e rod 24 therethrough into the cylinder 13. diameter of the bore through the body H is greater than the diameter of the bore through the casing to receive a sleeve 35 of wear resisting material and the inside diameter of the sleeve is such as to telescopically engage the upper end i of the sleeve 25. The sleeve 35 extends upwardly beyond the corresponding end of the sleeve 2'5, and a fitting 36 is brazed or otherwise secured to the upper end of the sleeve 35. The fitting 36 is secured to the piston 12, so that the latter, fitting 36 and sleeve 35 form an. assembly. The top of the sleeve 25 forms a seat for engagement with a head 31 at the top of the piston rod 24 to locate the piston K2 in its lowermost position in the cylinder i3 and the fitting 36 acts as an abutment for engagement with the head 31 to move the piston assembly upwardly in the cylinder.

Referring again to Figure 4 of the drawings, the body member H is detachably secured to the wall I 5 of the casing by studs 38 having the head portions accessible through the cored out openings 22 in the portion IQ of the casing. In this connection it will be noted from both Fi u 3 and 4 of the drawings that the body memb r ll The is also cored out wherever it is possible, to reduce the weight of the assembly to a minimum. The body is also formed with a pair of vertically extending passages 39 and All respectively forming continuations of the passages and 2!. The upper end of the passage 39 is counterbored to receive a check valve assembly M movable to its open position in response to movement of the piston [22 on its suction stroke in an upward direction in the cylinder 13 and movable to its closed position upon movement of the piston on its pressure stroke in a downward direction in the cylinder.

The valve assembly a l comprises an inverted cup-shaped casing 42 threadably engaging internal threads on the inner wall of the counterbore at the upper end or" the passage 39 and having laterally spaced openings 23 in the base portion. The lower or open end of the casing 42 is closed by a plate 65 suitably secured in the open end of the casing and having a central opening therethrough registering with the upper end of the passage 39. A flat polygonally shaped disc type valve member 45 is positioned within the casing 42 for vertical movement between the plate 44 and the base of the casing.

When the piston 12 is on its pressure stroke, the valve member 46 seats on the plate 44 and closes the opening 45 or passage 35. On the other hand, when the piston I2 is on its suction stroke, the valve member 46 is moved upwardly against the base of the casing 42. Due to the flats on the valve member 46 and due to the size of the openings 33, clearance is provided to en able fluid to flow from the upper end of the passage 39 past the valve assembly ll and into the space below the piston head.

A similar check valve assembly 48 is provided at the top of the outlet passage 40 and corresponding parts of the assembly 68 are indicated by the same reference numerals. It will be noted from Figure 6, however, that the check valve assembly 18 is inverted with respect, to the check! valve assembly H, so that the disc valve in the check valve assembly 48 opens in response to movement of the piston l2 on its pressure stroke.

The piston 12 is of inverted cup-shaped configuration having a head 53 and a skirt 54. The skirt 5d projects into the annular space 34 with the inner and outer surfaces respectively slidably engaging the body H and adjacent wall of the cylinder i3. Thus the piston is eflectively guided throughout its travel in the cylinder and leakage of fluid past the piston is minimized. In this connection it will be noted that any fluid leaking past the piston escapes into the inlet passage 18 through passages l8 formed in the reduced portion Id of the casing. These passages also serve as bleed openings to prevent trapping air into the space 34 below the piston skirt 54.

The head 53 of the piston is formed with an annular groove 55 forming a seat for the lower end of a coil spring 56 having the upper end abutting the top wall 29 of the cap 21. The spring 56 is the power means for moving the piston 56 downwardly on its pressure stroke, and is calibrated to suit the pressure required at the delivery side of the pump. This spring is positioned to be readily accessible upon removing the cap 2? and may be quickly replaced by a spring having different strength characteristics by merely removing the cap 21.

It has previously been stated that the piston I2 is moved upwardly in the cylinder [3 on its suction stroke by the push rod 2'4. Any suitable means may be provided for operating the rod 24, and accordingly, this disclosure is not complicated by a detailed illustration of such means. It will suiiice to point out that the rod 2 3 is moved upwardly by a push 'rod 5! having the upper end engaging the lower end of the rod 24 and having the lower end engaging a cam (not shown) operated by the internal combustion engine in accordance with conventional practice. Actually the upper end of the push rod El slidably engages within a fitting 58 suitably secured to the lower end of the piston rod '2 and having a portion forming a shoulder 59 for the lower end of a coil spring 60. The upper end of the coil spring 60 abuts a washer 6| engaged with the bottom of the casing ll} with the result that the spring 6!] tends to hold the head 3'! on the piston rod in engagement with the seat provided at the top of the sleeve 25. Thus the spring 6!! acts as a return spring for the piston rod 2 3 and maintains the lower end of the latter in operative relationship to the push rod '51.

Operation In the event the pump is employed for the purpose of supplying fuel to the carburetor of an internal combustion engine, the inlet port I8 is connected to a source of fuel supply and the outlet port I9 is connected to the carburetor. With this in view, it will be noted that each time the rod 24 is moved upwardly from the position shown in Figure 3 of the drawings, the piston I2 is also moved upwardly in the cylinder l3. Upward movement of the piston in the cylinder eiTects a reduction in pressure in the cylinder below the head 53 of the piston l2, and the resulting suction not only opens the check valve 4|, but also draws fuel into the cylinder below the piston head through the inlet passage El], 39.

When the piston l2 reaches the end of its suction stroke, the rod 2G is moved downwardly by the coil spring '66, and the piston is moved on its pressure stroke by the coil spring 53. As a result a pressure is created in the cylinder 53 below the piston head 53 proportionate to the strength of the coil spring 56, and the check valve 48 is opened. During this cycle or operation the check valve M is, of course, closed, and fuel previously admitted by the check valve i! is forced out of the outlet port l9 through the outlet passages What I claim as my invention is:

1. A pump comprising a casing having a 071- inder, a body member supported within the cylinder in concentric relation to the inner wall of the cylinder and cooperating with said inner cylinder wall to form an annular space, inlet and outlet passages formed in the body and communicating with the interior of the cylinder, a piston having a cylindrical skirt slidably supported in the annular space aforesaid and in slidable engagement with both the inner and outer walls of said space, said piston having a head portion located between said body and one end of the cylinder, means for reciprocating said piston, and check valves supported by the body member in positions to alternatively open and close the passages upon movement of the piston in opposite directions in the cylinder.

2. A pump comprising a casing having a cylinder open at one end, a body member supported within the cylinder in concentric relation to the inner wall of the cylinder and cooperating with said inner cylinder wall to form an annular space, inlet and outlet passages formed in said body member and communicating with the interi'or of the c'ylinder a piston having a cylindrical skirt in slidable engagement with both the inner and outer walls of said annular space and having a head portion positioned between the body member and open end of the cylinder, check valves supported by the body member in positions to alternatively open and close the passages upon movement of the piston in opposite directions in the cylinder, positive acting means for moving said piston on its suction stroke, a cap readily removably secured to the open end or" the cylinder, and a spring calibrated in accordance with the pressure requirements at the delivery side of the outlet passage and located between the cap and piston for moving the latter on its pressure stroke in a direction toward the body member.

3. A pump comprising a casing having a cylinder, a body member supported within the cylinder in concentric relation to the inner wall of the cylinder and cooperating with said inner cylinder wall to form an annular space, inlet and outlet passages formed in the body and communieating with the interior of the cylinder, a piston having a cylindrical skirt slidably engaging both the inner and outer walls of the annular space aforesaid and having a head portion located between said body and one end of the cylinder, means for reciprocating said piston, check valves supported by the body member in positions to alternatively open and close the passages upon movement of the piston in opposite directions in the cylinder, the engagement between said skirt and said walls constituting a seal which permits some leakage, and a bleed passage connecting said annular space below the piston skirt to the inlet passage.

4. A pump comprising a cylinder having a closed end, a cylindrical body in said cylinder defining an annular space therewith and having an end wall spaced from the closed end of said cylinder, a piston reciprocable in said cylinder between said body and the closed end of said cylinder and having a skirt slidably engaging both the inner and outer walls of the annular space, inlet and outlet check valves controlling fluid flow into the space between the end wall of said body and said skirted piston, said body having an axially extending opening therethrough, and a piston rod acting against the inside of said skirted piston recipr'o'cable therein.

5. A pump comprising a cylinder having a closed end, a cylindrical body in said cylinder defining an annular space therewithand having an end wall spaced from the closed end of said cylinder, a piston reciprocable in said cylinder between said body and the closed end of said cylinder and having a skirt slidably engaging both the inner and outer walls of the annular space, inlet and outlet check valves controlling fluid flow into the space between the end wall of said body and said skirted piston, said body having an axially extending opening therethrough, and a piston rod acting against the inside of said skirted piston reciprocable therein, said piston rod having one way engagement with said piston to move said piston away from said body, and spring means between the closed end of said cylinder and said piston for returning said piston toward said body.

6. A pump comprising a cylinder having a closed end, a cylindrical body in said cylinder defining an annular space therewith and having an end wall spaced from the closed end of said cylinder, a piston reciprocable in said cylinder between said body and the closed end of said cylinder and having a skirt slidably engaging both the inner and outer walls of the annular space, inlet and outlet check valves controlling fluid flow into the space between the-end wall of said body and said skirted piston, said body having an axially extending opening therethrough, and a piston rod acting against the inside of said skirted piston reciprocable therein, said piston rod having one way engagement with said piston to move said piston away from said body, and spring means between the closed end of said cylinder and said piston for returning said piston toward said body, said body having an annular sleeve extending in the opening in said body toward said piston and slidably engaged by said piston rod, and an annular sleeve extending outwardly from the inside of said piston and slidably engaging the outer surface of said first sleeve and the inner surface of said opening.

7. A pump comprising a cylinder having a closed end, a cylindrical body in said cylinder'defining an annular space therewith and having an end wall spaced from the closed endof said cylinder, a piston reciprocable in said cylinder between said body and the closed end of said cylinder and having a skirt slidably engaging both the inner and outer walls of the annular space, inlet and outlet check valves controlling fluid flow into the space between the end wall of said body and said skirted piston, and means for reciprocating said piston, the closed end of said cylinder being constituted by a removable cap, a strap having its ends shaped to engage with the outer surface of said cylinder, and a single clamping screw carried by said strap and engageable with said cap to press said cap on said cylinder in closing relation to an end thereof.

8. A pump comprising a cylinder having a closed end, a cylindrical body in said cylinder defining an annular space therewith and having an end wall spaced from the closed end of said cylinder, a piston reciprocable in said cylinder between said body and the closed end of said cylinder and having a skirt slidably engaging both the inner and outer walls of the annular space, inlet and outlet check valves controlling fluid flow into the space between the end wall of said body and said skirted piston, and means for reciprocating said piston, said valves being located r in the end wall of said body.

9. A pump comprising a skirted piston having an annular skirt and an annular sleeve concentrio with said skirt, a piston rod for reciprocating said piston concentric with and spaced inwardly from said sleeve, a cylinder within which said piston is reciprocable, a cylindrical body fixed within said cylinder and having its outer wall in sliding contact with the inner wall of said skirt, said body having a cylindrical opening therein, the wall of which is in sliding contact with the outer surface of said sleeve, a tubular guide fixed in said opening and having its outer surface in sliding contact with the inner surface of said sleeve, said piston rod being reciprocable within said guide sleeve, check valve controlled inlet and outlet passages for the flow of fluid through the space defined between said body and said piston, and means for reciprocating said piston.

10. A pump comprising a skirted piston having an annular skirt and an annular sleeve concentric with said skirt, a piston rod for reciprocating said piston concentric with and spaced inwardly from said sleeve, a cylinder within which said piston is reciprocable, a cylindrical body fixed within said cylinder and having its outer wall in sliding contact with the inner wall of said skirt, said body having a cylindrical opening therein, the wall of which is in sliding contact with the outer surface of said sleeve, a tubular guide fixed in said opening and having its outer surface in sliding contact with the inner surface of said sleeve, said piston rod being reciprocable within said guide sleeve, check valve controlled inlet'and outlet passages for the flow of fluid through the space defined between said body and said piston,

bleed passages connecting the annular spaces within which said skirt and sleeve are slidabl-e to the inlet passage, and means for reciprocating said piston.

HARRY J. WELCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Germany Sept. 10, 1925

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