US2818027A - Fuel pump - Google Patents

Description

Dec. 3l, 1957 w, E. BARNES -Er AL 2,818,027

FUEL PUMPl original Filed Nw:y 14, 1952 INVENTORS FUEL PUMP Witliam E. Barnes and Gordon W. Harry, Flint, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Continuation of application Serial No. 320,458, November 14, 1952. yThis application April 19, 1956, Serial No. 579,204 f 4 Claims. (Cl. 103-150) This invention relates generally to fuel pumps of the type commonly employed for supplying fuel to the engine of a motor vehicle from a fuel tank or reservoir, and is a continuation of abandoned application Serial No. 320,458'

filed November 14, 1952.

The invention aims generally toward the improvement of fuel pump mechanisms from the standpoint 4of reliability, maintenance and service and has among its specific objects to prevent binding and non-uniform wear of the parts of the pump operating mechanism and to eliminate leakage of pump lubricant from the pump casing.

The invention is especially suited for use in a pump of the type which employs for the movable element thereof a iiexible diaphragm which forms a movable wall for a pump chamber definedy within the pump casing. The pump casing has an integrally formed flanged portion for detachable mounting to the engine crank case and includes an operating linkage mechanism which is mounted in and extends through the said flanged portion into the pump casing. The pump operating mechanism is connected with the diaphragm for actuation thereof and comprises a pump operating link in operative engagement with an actuating lever or rocker arm, which projects from the flanged portion of the pump casing into the engine Crank case to engage a special cam on the engine camshaft driven by the engine. The link and rocker arm are pivotally mounted in the pump casing on a pivot or link pin which is pressed into a pin bore provided in the casing at or near the outer end of the flanged portion thereof. To secure the pivot pin in the bore and to seal the ends of the latter against leakage therethrough of lubricant for the pump operating mechanism supplied from within the engine crank case, it has been the practice, heretofore, to stake the pin in the bore, whereby both rotary and endwise movement thereof was supposed to have been prevented. l

It has been found, however, under actual conditions of operation, that the rocker arm tends to bind on the pivot pin during theA pumping process by reason of the motion thereof, and in addition to preventing reliable pump operation, ultimately results in loosening of the staked pivot pin, thereby causing substantial leakage of the pump lubricant without the casing through the pin bore and necessitating excessive maintenance and repair or replacement thereof.

For the elimination of these difficulties, the present invention provides, in a pump of this general character, a floating pivot pin which is journaled in the pump casing and is rotatable therein with the parts of the pump operating mechanism, thereby reducing or substantially eliminating the load of the rocker arm and the operating link on the pivot pin so as to prevent binding and to promote more reliable pump operation. The two-piece link and rocker operating mechanism also provides a ratcheting action which advances the rotative position of the freely rotatable pivot pin and provides uniform wear of the pin. In order to prevent endwise movement of the floating pivot pin and to seal the ends of the bore thereof, the

2,818,027 Patented Dec. 31, 1957 invention further contemplates the provision of retaining and sealing means in the form of cup-shaped plugs which are pressed into the pivot pin bore and are expanded or suitably locked therein.

The above and other objects, features and advantages attending the invention will appear more fully from the following detailed description and drawings; wherein:

Fig. l is a vertical section of a fuel pump structure which embodies the present invention;

Fig. 2 is a transverse sectional view taken in the plane f motive vehicles and which comprises, in general, a pumpl body or housing 10, a flexible diaphragm 12 and a pump operating or actuating mechanism 14. The pump body is a generally two-piece die-cast structure constituted by an upper casing 16 and a lower casing 18 which are detachably secured together by fastening means, such as screws, extending through the mating llanges 19 and 20, respectively formed thereon and between which flanges is clamped the diaphragm 12, substantially as shown. The upper casing 16 has secured to the upper surface thereof an inverted glass sediment bowl 22 held against a gasket 23, which is seated in an axially flanged upper wall 24 of the casing 16, by a bail or bowl retainer 26. The bail carries or bears against a screw 27 upon which is threaded a nut 28, the latter engaging a cup-shaped stamping 29 in contact with the bowl 22 to hold the latter in position.

Within the bowl and integrally formed with the upper casing 16 are an axially extending closed air dome 32 of generally cylindrical section, an arcuate wall 33, rwhich merges with the air dome to form a substantially crescentshaped space or region 34, and another arcuate wall 35, which extends from the Wall 24 and merges with the adjacent arcuate wall 33 to form a crescent-shaped pump inlet space or passage 36 therewith. The particular internal configuration of the pump casing, however, is not necessary to the understanding of and forms no part of the present invention.

The bottom of the upper casing 16 is recessed so as to form a pump chamber 38 between the diaphragm 12 and a wall 40 integrally formed in the upper casing. The pump chamber 38 has mounted over a pair of apertures formed in the wall 40 thereof a pair of pressure actuated Valve assemblies 42 and 44, which control the fluid low through the pump the inlet and outlet ports of which are shown as threaded passages 46 and 43, respectively. Detachably secured to and disposed around the upper end of the air dome 32 and the adjacent merging arcuate wall 33 is a wire strainer or screen 49 that filters any foreign matter in the fuel passing through the pump. The inlet port 46, which is connected by a fuel line to the fuel tank or reservoir, communicates with the pump chamber 38 through the passage 36, the interior of the bowl 22, the passage 34 and the inlet valve 42. From the pump chamber the fluid then flows through the outlet valve 44, the air dome 32, which functions to maintain the regularity of fluid discharge, and the outlet port 48, which is conneeted through a suitable line to the engine carburetor.

The lower casing 18 is a generally bowl-shaped structure with a wall 50, which has integrally formed therewith and axially extending on both sides thereof, a central stem portion 52, the bottom of which is closed, as shown. The generally cylindrical side wall of the stem tion integrally formed therewithand extending approximately normal thereto. The boss 54 has a rectangular passage 56 therein, which communicates with the interior of the stem 52, and is provided with a mounting ange 58 on the outer end thereof to permit the pump` casing to be detachably mounted to the engine crank case.

The diaphragm 12, which constitutes the movable element of the pump, may be composed of several layers of specially treated cloth, impervious to gasoline, benzol and the like, held together by a pair of metal disks or platesy 59, 60 and an actuator or pull rod 62, which is suitably secured to the disks :'59 and 60 and extends axially downwardly into the cylindrical stem 52. The upper end of the stem 52 has an oil seal 64 which is seated in a shoulder therein, and is maintained in position by an oil spring 66 between the oil seal 64 and diaphragm disk 60, as shown. The diaphragm spring 68 is shown surrounding` the spring 66 and seated between the wall 50 and the diaphragm disk 60 and serves to exert an upward force on the actuator rod 62.

The pump operating or actuating mechanism 14 comprises a pump actuating link or lever 70 and a rocker arm or lever 72 and extends through the passage 56. The pump operating link 70 is a one-piece stamping and has a latch or hook 74 formed on the end thereof that extends into the interior of the stern 52 and is received in an elongated aperture or eye provided in the adjacent end of the diaphragm actuator rod 62. The rocker arm 72 is of fabricated construction and is comprised of a pair of generally L-shaped members 72a between which is disposed a spacer member 72b, all of which members may be of stamped construction and are suitably secured together, as by rivets 75. The ends of the L-shaped rocker arm members 72b, within the passage 56, extend beyond the rocker arm spacer member 72a so as to provide a yoke or clevis which receives the adjacent shouldered end 76 of the operating link 70. The link and arm are secured together by and are pivotally mounted on a shaft or pivot pin 78, which is journaled in a bore 80 (Figures 2 and 3) extending substantially transversely through the walls of the passage 56 near the flanged end 58 of the boss portion 54 of the lower casing 18.

The rocker arm 72 emerges from the passage 56 in the lower casing and projects `into the engine crank case through an opening in the latter to engage an eccentric cam 79 on the engine cam shaft 81 and works against a rocker arm spring 82 seated on protuberances 84 and 83, which are formed on the pump casing and on the rocker arm spacer member 72b, respectively, as shown. The spring 82 serves to maintain constant contact of the outer end of the rocker arm 72 with the cam 79. The end 76 of the link 70 forms a cam shoulder which engages a complementary abutting camming shoulder 86 formed on a part of the end of the rocker arm spacer member 72b, whereby under the action of the cam the rocker arm and link may swing as a unit and pull the actuator rod 62 and make a suction pump stroke. The discharge pump stroke is made by the diaphragm spring 68.

In accordance with the present invention, the pivot pin 78 is of such diameter relative to the bore 80 thereof so as to be tloating therein, thereby to eliminate binding of the parts of the operating mechanism encountered in prior art constructions, as explained hereinabove. The pin is thus rotatable with the elements of the pump operating mechanism.

In order to prevent endwise movement of the pivot pin 78 and to seal the ends of the pin bore 80 so as to prevent leakage of the pump lubricant splashed onto the pump operating mechanism from within the interior of the engine crank case, there is provided a pair of retaining means, preferably in the form of cup-shaped plug members 88, which are pressed into each end of the bore. The cup members are constructed, preferably, from brass stampings and are held in the bore by frictional engagement with the walls thereof.

Figure 3 illustrates a slightly different embodiment of` the invention wherein an annular groove 89 is formed within the pin bore 50 near each of the outer ends thereof, whereby the cup-members 88 may be expanded upon in sertion in the bore so as to be positively locked therein.

It is apparent that other forms of seal and retaining means could be employed in addition to the specific ar rangements 88 shown and described herein, which are simply illustrative of the application of the principles of the invention.

lt also should be noted that the use of a two-piece pump actuating mechanism in combination witha floating pivot pin results in the provision of a ratcheting action of the pivot pin so as to provide uniform wear around the surface thereof and to prolong the service life of `the pin. When the rocker arm 72 is moved upwardly or in a counterclockwise direction, its camming shoulder 86 engages the upper portion of the end 76 of the link 70 and exerts a pressure or load thereon which is opposed by the force of the spring 66 applied through the rod 62 and link 70. Since the point of engagement of the link and rocker arm is displaced from the center of the pivot pin, a heavy side load will be applied to the pin as the rocker arm is further rotated counterclockwise to overcome the force of the spring. The rocker arm and link thus will be frctionally bound on the pin and rotate the pin in its bore on the down stroke of the pump. The walls of the bore provide the bearing surface for the pin, rocker arm and link during this stroke.

On `the up or return stroke of the pump, the side loading of the pin is relieved and the rocker arm follows the upward movement of the link under the influence of the spring 66. The connecting link and rocker arm rotate on the pivot pin 78 which remains stationary in the bore, and itself provides a bearing surface for the connecting link and the operating arm. Thus, uniform wear of the pivot pin is assured and less stressing and wearing of the bearing surface of the pin bore are encountered.

What is claimed is:

l. In combination, a pump comprising a walled casing including a pump chamber, a diaphragm forming a movable wall for said chamber, said casing having a bore extending through the walls thereof, a pump operating lever extending into said casing and coupled to said diaphragm, a floating pivot pin for said lever journaled in said casing bore and extending transversely through said lever and expandable cup-shaped sealing means within said casing bore and bottomed against the ends of said pivot pin,

2. In apump having a walled casing defining a pump chamber therein, a diaphragm forming a movable wall for said chamber, pump operating means in said casing coupled to said diaphragm, a oating pivot pin journaled in a bore in the walls of said casing and forming a rotatable pivot for said pump operating means, and a pair of thin-walled cup-shaped plug members expanded in said bore and bottomed against the ends of said pin therein, each of said cups having a circumferential outer rib thereon registering with a complementary groove in the wall and near the end of said bore.

3. In combination, a pump comprising a walled casing including a pump chamber therein, a diaphragm forming a movable wall for said chamber, said casing having a bore extending through the walls thereof, pump operating means in said casing and including an actuator rod connected to said diaphragm, an operating link coupled to said actuator rod and a rocker arm operatively engaging said operating link, a floating pivot pin rotatable in said casing bore and providing a pvot for said operating link and said rocker arm, and retaining means for said pin positioned in the ends of said bore, said operating link and said rocker arm being locked on said pin and being rotatable therewith during one stroke of said pump and belng free to rotate thereon during the other stroke of the pump;

4. ln combination, a pump comprising a walled casing including a pump chamber, a diaphragm forming a movable wall for said chamber, said casing having a bore eX- tending through the walls thereof, a pivot pin freely rotatable in said bore, an actuating lever pivotally mounted on said pin and connected to said diaphragm, a rocker lever pivotally mounted on said pin, said levers including engageable abutment surfaces extending transversely of said pin in the vicinity thereof whereby rotative motion may be transmitted from the rocker lever to the actuating lever, a first spring interposed between the diaphragm and the casing operative to oppose rotation of the actuating lever in one direction, a cam engaging said rocker lever for rotating the rocker lever and actuating lever in said one direction about said pin for displacing the diaphragm, whereby opposed forces cause said levers to seize said pin therebetween and rotation of the pin therewith, said first spring being also operative to rotate the actuating lever and to displace the diaphragm in the other direction, a second spring interposed between the rocker lever and said casing urging rotation of the rocker lever in the said other direction, whereby said levers are rotated independently in the said other direction relieving the seizure of said pin to release the same in its rotated position, and retaining means for said pin positioned in the ends of said bore.

References Cited in the le of this patent UNITED STATES PATENTS 2,036,452 Babitch Apr. 7, 1936 2,057,624 Burkhart Oct. 13, 1936 2,426,965 Coffey Sept. 2, 1947

Images