US1893216A - Linkage for fuel pumps - Google Patents

Description

Jan. 3, 1933. A; M. BABITCH LINKAGE FOR FUEL PUMPS Filed March 15, 1928 Patented Jan. 3, 1933 UNITED STATES ABRAHAM M. BAIBITGH, OF-FLIN'1,, MICHIGAN LINKAGE FOB FUEL PUMPS Application filed March 15, 1928. Serial No. 261,916.

This invention relates to improvements in variable stroke pumps and has been designed more particularly as an improvement in a variablestroke fuel pump for use in connection with the fuel supply system of an internal combustion engine, the present application constituting a continuation in part of my application Ser. No. 123,370, filed July 19,1926. a

An object of' the invention is to provide an improvement to positively prevent a continuous pumping action. As a further and more specific object, the invention employs a pair of articulated links having associated therewith means to assure their collapse after they transmit the suction stroke, and so con-- structs the linkage as to positively prevent alignment of links. As a related object, the invention aims to secure the action of such linkage without undue noise. Other objects including simplicity in construction and economy in manufacture will be understood from a reading of the following description and an examination of the accompanying drawing. The invention might be embodied in several forms, a few of which are illustrated in the drawing.

section. of the form illustrated by Figure 2.

Referring by reference characters to the drawing, numeral 5 represents as an entirety a fuel pump for use with an internal combustion engine, the pump serving to draw fuel from the gas tank carried by the vehicle and delivering the fuel to the carburetor. The pump is to be operated by suitable means associated with the engine.

The pump comprises a pump body 7 and a cover member 9. Clamped between the body and cover is a flexible diaphragm 11. The

space above the diaphragm 11 and beneath the cover constitutes the variable volume chamber ofthe pump. The space within the body 7 and beneath the diaphragm is preferably open to the air as at 13 so that this space may be always subject to atmospheric pressure. Within this body space and centered by a boss 15 is a spring 17, this spring being in abutment at its lower end with the base of the body portion and engaging at its upper end a disc 19 beneath the diaphragm 11. A disc 21 is located above the diaphragm. These discs, together with nut 23, clamp the diaphragm to a reciprocating rod 25 slidably movable through the boss 15. The cover is preferably extended at one side of the body and this extension supports by means of a bail 27 a filter cup 29, the bail being hooked into the cover at its ends as shown at 31. At the bottom of the bail beneath the cup is a screw eye, the eye surrounding the bail as at 33. On the stem of the screw eye is threaded a nut- 35 exerting upward 'pressure against a member 37, which fuel supply tank will be understood to be so the reservoir, usually carried'at the rear end of the vehicle and at a level below that of the carburetor. The cover also is provided with a passage from the pipe line 39 to the filter cup, a passage from the filter cup to the pump chamber, and an outlet for connecting the pump chamber by means of a. pipe to the carburetor float chamber. The cup also has an inlet valve or an outlet valve. This cover construction is only partly illustrated as the plug 43 which may be removed to give'access to the outlet valve and a similar plug 43 which may be removed to give access to the inlet valve if such is provided in the cover 9.

The pump body is formed with an opening and pivoted near the opening on pivot pin 47 is a lever 49 extending outwardly from the pump. The pump body is to besecured to the motor block and the lever 49 projects into the motor block where it is engaged by a cam 51 carried by a camshaft 53. It will be seen that the cam rocks the lever in one direction of rotation only. A spring '55 is seated against cap 57suitably carried by the pump body. The spring engages the lever 49 within the pump body and tends to rotate the lever in a direction opposite to the rotation given the lever by the cam. The spring of course holds the lever at all times in contact with the cam. A link connection is made between the inner end of the lever and the reciprocating rod 25 whereby the action of this spring will be against the compression of the fluid in the pump chamber. Itwill be seen, therefore, that the discharge stroke is never positive and. that no fuel will be discharged from the pump unless the spring 17 is able to overcome the fluid pressure in the pump chamber. It will also be seen that the suction stroke, when such a stroke occurs, is always positive, there being no resilient element in the linkage.

This invention is concerned primarily with the linkage between the pump plunger 25 and the lever 49. The novel linkage is designed to positively prevent the pos ibility of the cam 51 or the spring acting to give a discharge stroke to the diaphragm. To that end, as shown in Figure 1. the linkage comprises an upper link 61 recessed to straddle a reduced lower end 63 of the plunger 25. The reduction of the plunger end and the dimension of the recess in link 61 is such as to permit free and unrestricted relative swinging of link 61 about its pivot 62 with the plunger through any angle within the range of action required. The lower end of link 61 is cutaway on its sides to form an end portion 65 of reduced thickness. which end portion is straddled by forks 67 formed by a recess in the upper end of link 69. Pivot pin 71 connects links 61 and 69. Particular attention should be given the construction of means. associated with said links. to insure the collapse thereof under thrust. such means being shown at the adjacent ends of links 61 and 69. The end of link 61 has its curved extremity on an arc struck from the link 61 to a point substantially in that center line. The shoulder then continues on an are about pin 71 as a center and having the same radius as that of the rounded end of link 69. The curved shoulder continues beyond a line at right angles to the center line through pin 71. As a result of this construction. links 61 and 69 may collapse in one direction to an extent in excess of any range of such movement which may be required. The extension of the curved end 72.0f the shoulder port-ion beyond the normal to the center line through the pins 62 and '71 prevents link 69 reaching alignment with link 61. As such alignment is approached, the side wall of link 69 is engaged by the extended part 72 of the link 61. The lower end of link 69 is reduced in thickness to an extent indicated by line 73 and this reduced end. is received within the forked end of lever 49, numeral 74 being applied to the pivot pin between lever 49 and link 69. The extent of the recess between the forks of the lever and the extent of reduction in thickness of link 69 are sufiicient to give all the relative motion required between the lever 49 and the link 69.

In operation. assuming the parts to be in the position shown in Figure 1, as the cam rotates it swings lever 49 in a counterclockwise direction and straightens or tends to straighten links 69 and 61 until the shoulder projection 7:2 of link 61 engages the side edge of link 69, which engagement occurs without the links attaining alignment as explained above. The continued movement of the lever pulls down upon the plunger 25 and the diaphragm 11 and draws fuel into the variable volume chamber of the pump.

After the suction stroke is completed. spring 55 gives to lever 49 a clockwise rotation to hold the lever upon the cam. Such movement of the lever under the influence of spring 55 cannot push plunger 25 upwardly since the links are out of alignment and merely tend tocollapse. If the fuel drawn in by the suction stroke is insufiicient to overcome spring 17. which has of course been compressed as the diaphragm was pulled down, that spring will execute a discharge stroke and deliver fuel through the exhaust valve 41 to the carburetor. If the pressure is sufficient to overcome spring 17 (as when the carburetor requires but little fuel) no discharge may occur. Under these circumstances. no diaphragm movement occurs. the

action of lever-49 being accommodated. by the relative movements of the links 61 and 69.

lapsing direction, as far as is required to accommodate the cam movement, diaphragm flexing does not occur unless needed to producea suction or discharge stroke. Since the linkage can never reach alignment, the clockwise movement of lever 49 cannot act upon the diaphragm to make a dischargestroke, such movement merely collapsing or tending to collapse the-linkage, actually collapsing the linkage when the pump chamber pressure is high and tending to do so when the pump chamber pressure is low. The compression stroke of the pump effected by spring 17 tends to wholly or partly prevent the collapse of the linkage under the influence of the clockwiserotation of lever 49.

The construction described therefore insures a pumpaction wholly resilient in its discharge stroke and wholly positive. in its suction stroke, the suction and discharge strokes only occurring when the fuel de- V nations 87. This is a convenient and eco-' mands require pump action. No positive action of discharge can possibly occur through the reverse motion of the parts giving the suction stroke. 1

In Figures 2 and 5 is a second form in which the invention may be embodied. In this form, the plunger 25 has its lower end reduced as before, as shown by reference character 81. The end 81 is received and pivoted by means of pivot pin 85 between a. pair of links 83, which are alike in construction. Preferably these links 83 are made of laminomical form of construction and serves as a substitute for link 61 in the form already. described. A pin 89 at the lower end of links 83 pivotally connects these links with a link 91. Link 91 is pivoted for free and unrestricted movement in the recessed end of lever 49 on pin 93. Intermediately positioned on links 83 is a pin 95 located substan tially in the center line a- -a between pins 85 and 89. Retaining means 97 are shown associated with each of the pins. Pin 95 is in the nature of a stop and serves to limit the movement of link 91 as it approaches alignment with 'links 83. The upper end of link 91 on its edge adjacent pin 95 is cut away permitting link 91 to enter to a limited extent between links 83 before the said link 91 engages the pin 95. The cutaway surface is curved on an are about pin 89 as a center with a radial length, such as tohave a minimum clearance with pin 95 as the links straighten. The curved surface, best shown in Figure 5, ends in a flat surface substanshown tially parallel withthe edge of the link. As a result, when the links swing about pivot pin 89 the surface of pin 95 and of the curved end of link 91 lie closely adjacent up to the relative positio where the end surface of the link positive y engages the pin and stops the movement. The operation of the linkage in this form of the invention is substan tially the same as that in the form already described.

In Figure 3 is another form of the inven-' tion. The plunger 25 is the same as in the forms already described. The link .83 may also be the same except for the location of the pin 95' which corresponds in'general to the pin 95 shown in Figure 2. In Figure 3, this pin 95' is positoned off the center line of pins 85 and 89 slightly to the right. as by the line BB. The drawing shows the offset somewhat exaggerated for the purpose of better illustration. Link 91 corresponds to link 91 of the other form but is of somewhat modified construction. Its upper end is, as in the case of link 91. curved on an are about pin 89 and with a radial distance such as to give a minimum clearance with pin 95'. At the end of the arc. instead of being shaped in parallelism with the edge of the link as in Figure 2 and Figure 5. the curved surface merges into a tangent to the curved portion. It is this tangential end which engages pin 95 to prevent alignment of links. Since atthe region of contact the end is tangent to the curved part, the contacting end very gradually. instead of suddenly, engages the stop pin. By this means the tendency to click associated with the act of contact between the stop pin and the link is avoided, or greatly'lessened.

It will be understood that the provision for stopping the relative movement by contact of the pin 95 with the tangential surface of 1 the link will be effective in preventing noise to an extent depending upon the point or line of contact of the tangential surface engaging the pin." If the radius of curvature of the end of link 91 is such as to give minimum clearance with pin 95. the contact with the tangential surface must be just at the point Where the curve merges into the tangent. This results in a sort of wedging engagement with a reduction of the noise to a minimum. If, under 'these circumstances. the pin were in the center line of pins 85 and 89, such wedging engagement might so effectively tend to lock the links together that the reverse rotation of lever 49 acting upon the linkage might be incapable of overcoming the wedging action. To avoid such a result, the pin 95' is offset slightly, as shown in the drawing, from the center line of the pins 85 and 89 so that the wedging force is out of the line of centers and the force exerted through the line of centers is capable of overcoming the resistance of the wedging action at the stop pin 95.

In Figure 1 is still another form of the invention. In this form, the plunger rod 25 is the same as also is lever 19. Link 101 is unlike its counterpart. It is forkedas at 103 to engage the reduced end of rod 25 for free pivotal movement about pivot pin 85. Its lower end is curved and forked as shown at 105. It has a pivot pin 109 within the forked end and a terminal stop pin 110. Link 111 is freely pivoted to the forked end of lever -l9 as in the other forms of the invention. The upper end of link 111 is rounded, its end being in the form of an arc about 109 as a center. Link 111 may swing freely for the collapse-movement of the links. In doing so. the radial length of itscurved end is such that it has a minimum clearance with stop pin 110. This pin 110 will engage the edge of link 111 at the point where its curved end merges into the tangential edge. The relative positions of the pin and link are such as to stop the relative movement before alignment of links mav occur. and the wedging tangential action avoids the noise in a manner similar to that described in connection with the construction shown in Figure 3. Moreover. this wedging action occurs at a. point. out of the line of centers through pins 85 and 109 with the result'that the wedging force is incapable of preventing the collapsing of the links under the clockwise rotation of lever -19. I

I claim:

1. In a fuel pump including a reciprocable pumping member. a cam-actuated lever for conditionally moving said member in one direction b v means of a lost motion connection; said connect-ion comprising jointed links. one of said links being pivoted to said pumping member and the other of said links being pivoted to said lever. and means adjacent the common pivot between said links to prevent their alignment comprising a stop pin on one of said links and a cooperating stop surface on the other of said links.

. 2. The elements set forth in claim 1, in which said stop pin is carried by the link pivoted to the pumping member and is located out of the line of centers of the two pivots of said link.

3. The elements set forth in claim 1, in which said stop pin is carried by the link pivoted to the pumping member and is intermediate such pivot and the common pivot between the links.

4. The elements set forth in claim 1, in which said stop pin is carried adjacent the end of one of the links with the common pivot intermediate the ends of such link.

5. In a fuel pump comprising a reciprocable pumping member, resilient means to move said member in one direction and means to move said member in the opposite direction my signature. ABRAHAAI M.

BABITCH.

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