US2265613A - Automatic variable delivery fuel pump - Google Patents

Description

Dec. 9, 1941. A. J. RICHARDS AUTOMTIC VARIABLE DELIVRY FUEL ,PUMP

Filed Sept. 9, 1940 2 Sheets-Shea?I l l. mm. ma NGN.

Dec. 9, 1941. A. J. RICHARDS AUTOMATIC VARIABLE DELIVERY FUEL PUMI? Filed Sept. 9, 1940 2 ShemEs-Sheeil 2 E nventor Patented Dec. 9, 1941 Arthur nichel-ds, Lansing, Mich.

Application September 9, 1940, Serial No. 355,927`

10 Claims.

This invention relates to pumps and in particular to variable-delivery constant-pressure pumps.

One object of this invention is to provide a .variable-delivery pump having means associated therewith for maintaining a substantially constant pressure in the output circuit of the pump regardless of the speed at which the pump is driven.

Another `object is .to provide avariable-delivery constant-pressure pump employing a bellows mechanism for pumping the fluids and having means responsive to the increase of pressure in the output circuit of the pump for varying the stroke of the pump, thereby maintaining a substantially constant pressure in the output circuit thereof.

Another object is to provide a variable-delivery constant-pressure pump having an automatically-adjustable lostmotion connection between the actuating mechanism and the pumping mechanism, this lost motion connection being automatically adjustable in response to an increase in pressure in the output circuit of the pump so that the pump stroke is automatically reduced with an increase in output pressure while the actuating stroke remains the same.,

Another object is to providea variable-deliv ery constant-pressure pump as set forth in the Ypreceding objects wherein a thermostatic element. is interposed for automatically increasing the stroke-varying pressure in order to overcome the vapor lock condition sometimes occurring when the motor is operated under higher than normal temperatures, so that the pump will continue to operate at full stroke until the output pressure rises to a higher level than the normal level at which the stroke-reducing mechanismA becomes operative at normal temperature.

In the drawings:

Figure 1 is a central vertical section through a preferred embodiment `of the pump of this invention.

Figure 2 is a horizontal section approximately along the line 2-2 in Figure 1 showing the lost motion connection which -is automatically adjustable to provide a variable str oke for the pump. 1 I

Figure 3 is a vertical section taken along the line 3-3 in Figure 1 and comprising a longitudinal section through the lost motion connection.

Figure 4 is a horizontal section through the upper bellows of the pump taken along the line 4 4 in Figure 1. l

Figure is a fragmentary vertical section'of the upper part of Figure 1, but showing the thermostatic mechanism after it has operated in response to a predetermined' rise in temperature to increase the pressure level at which the stroke reduction becomes effective.

Figure 6 is a fragmentary view of a modification of Figure 1 employing a dome-like diaphragm instead of a bellows.

General arrangement y In general, the variable-delivery .constantpressure pump of this invention consists of a. pumping device, such as a bellows, which is actuated from a cani shaft through a` lost motion connection. This-lost motion connection determines the stroke which shall be applied to the pumping mechanism independently of the stroke applied by the cam shaft.

The lost motion connection is varied automatically in its adjustment in response to the rise of pressure in the output circuit of the pump. When the pressure increases4 to a predetermined level, a cam mechanism permits the lost motion device to open more or less, according t'o the output pressure attained. As the lost motion device opens, the stroke actually applied to the pumping mechanism is automatically' reduced even though the stroke of the cam shaft remains constant.

As a further feature, the pump is equipped with a thermostatic device which automatically increases the stroke-reducing pressure toa higher level in response to a rise in temperature. This featurel is especially important in fuel pumps, where high operating temperatures often create vapor locks and consequently prevent the pump from delivering the proper amount of fuel to the engine. With the thermostatic ldevice of this invention. the operating level of the pump is automaticallystepped up to a higher pressure level when the temperature reachesa predetery mined height.

The variable-delivery constant-pressure pump of this invention is particularly valuable in use as a fuel pump for internal combustion engines,

4especially gasoline engines. In s'uch engines, it

is very important that a reasonably constant output pressure shall be maintained, so that the engine will always be supplied with fuel throughout y a wide range of operating conditions from slow designated 33 (Figure 3),.

invention, however, the static pressure in thev output circuit remains substantially constant regardless of thepower input variation over a wide range of speeds.

and' contraction of the upper bellows and has also been veried by actual experimental tests.

vMoreoverI an outlet pressure adjusting screw is additionally provided to enable outlet pressure of the pump to be adjusted to suit individual car-4 buretor requirements, and also to` adjust the Y thermostatic device.

Pump construction Referring to the drawings in detail, Figure 1 shows a preferred embodiment of the pump of this invention as consisting of a casing having an intake connection and an intake passage duced diameter portion 25 of a pin 26, the enlarged portion of which enters a. bore 21 in an internal tubular projection 23 of the pump casing |0. -The tubular projection 23 extends downwardly from the partition member'23 forming an internal bulkhead in the pump casing i0, and serves as a guide for the reciprocation of the pin y26. The opposite end of the pin 26 is enlarged as at 30 to clamp a and 23.

The yoke 3| is provided with ears 32 carrying a shaft 33 which in turn engages the driven arm yoke 3| against the disks 22 '34 by passing through a bore 35 therein (Figure 2). The driven arm 34 at its opposite end'is provided with an eye 36 which is slipped over a sleeve-like projection 31 within the driven cam member 33 of the lost motion device generally The end of the sleeve portion 31 is upset as at 40 to secure the arm 34 tightly to the driven cam member 33.

'I'he driven cam member 33 is provided with triangular tongues 4| (Figure 2) engaging corresponding triangular notches 42 in a driving cam member 43. The latter is provided with an internal sleeve portion 44 carrying the intermediate portion 45 (Figure 3) of a driving arm 43. The inner end of the driving arm 46 is bent as at 41 and has a coil spring 43 connected thereto as at 43 (Figure 1), the opposite end of the 'spring` being anchored as at l0 to the lug 5| on 1 the inside of the casing cover plate 52. The latter is secured by the screws 53 to the rim-54 of the casing l0, thus serving as aclosure for the latter. 'I'he outer endv of the driving arm 46 is arched as at 35 (Figure 1) and y mounted upon the cam shaft 51.

engages a cam 53 The driving and driven cam portions 43 and 33 (Figure 3) are providedwith bores 53 and 33 y respectively. which receive a shaft 30 secured within the casing bores 6| and 32 by the pins 63 1 extending through the end holes 34 in the shaft 33.' A washer 6l is interposed between the driving cam member 43 and the Yinterior of the pump i casing I0. A coil spring 33 within the driving This results from the variation' of the pump strokein response to the expansion upon which is mounted an arm secured there-v and driven cam members 43 and 33 serves to i urge these members apart, thus tending to cause the triangular tongues 4| in the driven cam 33 to withdraw from the notches 42 in the driven cam member 43. When this occurs. only a portion of the stroke imparted to the driving cam member by the cam 56 and driving arm 46 will be transmitted to the driven cam 33 and driven arm 34, and thence to the pumping diaphragm I1. 1

'I'he driven cam 33 is provided with a conical end surface 61 which is engagedby the conical end 63 of an axially'reciprocable cam rod 63 which is reciprocable in the aligned bores 10 and 1| of the tubular guide portions 12 and 13 extending in opposite directions from the partition member 23 (Figure 1). The upper en d of the cam rod 63 has a reduced diameter portion 14 to by the enlargement 16.

The arm 15 `extends radially inward and at its inner end is provided with a bore 11 which surrounds the sleeve portion 13 of the spring cap 13,v

the latter` in turn surrounding the reduced dif ameter portion 30 of the pin 3i. Also mounted on the reduced diameter portion 30 and held thereon in a similar way are the twin disks 32 and 83, between which is clamped the end 34 of the upper bellows 35. The opposite end of the upper bellows 35 is clamped against thev partition member 23 by an annular member 36 also held in position by the screws 2|. The screws 2| also serve to retain in position a cover cap 81 for covering the upper bellows 35.and its associated mechanism.

The cover cap 31 is provided with a threaded plug 33 secured thereto as at 33. Threaded into the bore 30 of the plug 33 is an adjusting screw 3| equipped with a lock nut 32 for holding it in any adjusting position. The lower end ofthe adjusting screw 3| is provided with a reduced diameter portion 33 terminating in an enlarged head 34 which serves as a retaining flange for a disk 35 having an aperture 31 therein. A bimetallic thermostatic disk 36 is secured as at 33 .to the adjusting screw 3|. Extending between the disk 35 and the spring cap 13 is a'compression coil spring 33 which serves to urge the bellows 35 toward its collapsed position. At the same time, the spring 33 also urges the cam rod 63 downward in a direction causing the lost motion connection 38 to close and take up its lost motion.

The bimetallic disk 36 is composed of two metallic disks |00 and |0I held together at their edges as at I||2 and composed of materials of different coeicients of expansion. As a consequence.- with a rise in temperature, one disk expands more rapidly than the other, causing the assembly to assume a bowed or. cupped condition, as explained below.

The passage of iiuid from the lower bellows I1 to the upper bellows 35 isregulated by the valve disk |03-mounted in the valve body |04, the latter being provided with a port |03 aligned with,

the port |03 in the partition member 23 (Figure 1). Accordingly, the valve member |03 opens upon the compression stroke -of the bellows 1, the valve member I5 thereof opening upon the suction stroke.

The partition member 23 (Figure 4) is provided with an outlet port |01 opening into an outlet passageway |03 terminating in an outlet connection |03. The outlet conduit thus formed conducts the fluid from the interior of the bellows 35 to the pipe leading to the carburetor or other point of utilization of the .iiuid pumped by the pump. l In the modication shown'in Figure 6, one or both of the bellows '|1 or 35 is replaced by a diaphragm ||0. The latter is Vsecured at its outer of the construction is the same as shown in Flg` ure 1 and corresponding parts bear similarreference numerals.

Operation In the operation of the pump shown in yFigure 1, the starting of the engine causes the cam .f

shaft 51 and cam 56 to rotate, moving the driving arm 46 up and down and consequently moving the driven arm 84 and the bellows |'1 up and down, provided the lost motion connection 39 is closed, as shown in Figures Zand 3. This condition will occur when the engine is first started and there is very little pressure Within the upper bellows 85, permitting the cam rod 69 to be pushed downward by the coil spring 99, closing the lost motion device 39.

As the bellows I1 expands on the downward stroke of the pin 26, the valve member |5'moves downward oil its seat and permits fluid to be drawn through the connection and the passageway I2 through the port I3 intothe chamber I6 within the bellows l1. When the pin 26 moves upward, however, and the bellows I1 is thereby collapsed, the fluid within the bellows |1 is forced through the ports |06 and |05 into the interior of the upper bellows 85, lifting the Y valve member |03 to open this communication. l Due to the pressure of the fluid forced into the interior of the upper bellows 85, the pressure thereon is eventually sufficient to overcome the thrust of the coil spring 99 and expand the bellows 85. This lifts the arm 15 and cam rod 69 when the pressure reaches a predetermined amount. Such an increase in pressure occurs when the. amount of fluid being pumped into the bellows 85 is greater than the amount of fluid being taken out through .the passageway |08, such as when the .pump is` pumping more fuel than the engine is capable of using up at an idling speed.

When the cam rod 69 rises in response to an increase in pressure within the upper bellows 85, the elements 38 and 43 ofthe lost motion device 39 are caused to separate under the urge of the coil spring 86 (Figure 3), moving the triangular tongues 4| out of their notches 42.

When this occurs, the arm 46 and member 48 move for a certain distance before the edge of the notch 42 encounters the edge of the tongue 4|. As a consequence, only a part of the stroke of the driving arm 46 is transmitted to the driven arm 34, and the bellows |1 executes only a part of its full stroke.

As a result, the volume of fluid pumped into the upper bellows 85 during a given time interval is considerably reduced, so that the expansion of the bellows 85 is retarded,'provided that fluid is lbeing withdrawn from its interior through the port |01 and passageway |08y (Figure 4). Y v

In the event that the engine isidling and the fuel is being pumped into the interior of the bellows 85 much more rapidly than it is being used pp by the engine, the bellows 85 will be greatly expanded. causing the cam rod 69 to rise through a substantial distance and permit the elements 38 and 43 of the lost motion device 39 to separate to an extent where no motion whatever is transmitted from the driving arm 46 to the 4 driven arm 34.

kment yagain resumes its upwardly concave condition When, however, enough fuel has been used up by the engine to reduce the pressure within the upper bellows 85, the coil spring` 99 forces` the latter downward, and with it, 'the arm 15 and cam rod 69. This action urges the element 38 toward the A element 43, thus causing the tongues 4| to enter the notches 42. When the tongues 4| fully enter the notches 42 (Figure 2), the lost motion is entirely taken up by the lost motion device 39, and the full stroke of the driving arm 46 is transmitted to the driven army 34,

causing the bellows |1 to execute its full stroke. i During very hot weather, the high temperature frequently vaporizes the fuel being pumped, so that the bellows 85 contains a gaseous vapor instead of liquid fuel. This gaseous vapor would serve as a vapor lock and soon bring the engine to a halt,'because'although the pressure of the vapor within the bellows 85 is still sufficient to expand the latter and raise the cam rod 69, only gas` and not liquid fuel would be supplied to the outlet port |01 and passageway |08.. Under these conditions.. the engine` would halt `by its lack of sufllcient fuel.

Toovercome this .vapor lock condition, the engine provides the thermostatic disk mechanism shown in the upper part of Figure l. At ordinary temperatures, the bimetallic disks |00 and |0| will assume the upwardly concave condition shown in Figure l. When a high rise in temperature occurs, however, the vmetallic ele-l ment` |00, with the greater coefiicient of expansion, will expand more rapidly than the metallic velement |0|, causing the unit 96 to become convex upwardly (Figure 5). Thus the edges ofthe unit 96 press the disk 95 Adownward and this adsnap action results in a quick and abrupt shift.

from one pressure level to the other as the temperature changes.

The eiect of this additional compression of the coil spring 99 results in the necessity for the bellows I1. to pump more fluid into the upper bellowsA 85 to raise the arm 15 and cam rod 69.

and open the lost'motion device 39. The additional fluid thus pumped relieves the vapor lock condition and supplies the necessary fluid for the engine.

vWhen ythe temperature returns to normal, the greater contraction of 'the upper element |00 causes it to contract more rapidly than the ele- |00, whereupon the, bimetallic `unit 96 (Figure l) and the pump is automatically adjusted to .operate the losty motion device 39 at the lower pressure level.

The operation of themodification shown in Figure 6 is similar to that of the main vform of the invention shown invFigure l.` `ThisA form of the invention, however, is useful where onlya short stroke is required and the expansion of a bellows `is not needed. l

With either form of the invention, the delivery of the pump is automatically altered by the closing or opening of the lost motion device 39,

, thereby causing the output pressure to remain substantially constant regardless of the increaseincrease in the number of pulsations per minute of the bellows I1.

, While I have shown and described my invention in detail, it is to be understood that the same is to be limited only by the appended claims for many changes 'may be made without departing from the spirit and scope of my invention. j

What I claim is: 1 1. In a variable-delivery pump, a reciprocable pumping device, a driven element connected pumping device, a driven element connected thereto, a driving element, a separable strokeing an expansible device responsive to the attainpressure in said outlet circuit for urging said projection into said recess whereby to close said separable connection and increase the stroke of said pumping member. l

6. In a variable-delivery pump, a casing, a reciprocable pumping means associated therewith having an inlet circuit and an outlet circuit,

a driven arm connected tosaid pumping means, a` power-operable driving arm, and an interengaging tapered tongue and notch connection interposed between said arms.

7. In a variable-delivery pump, a casing, reciprocable pumping means associated therewith having an inlet circuit and an outlet circuit, a driven arm'connected to saidl pumping means, a power-operable driving arm, an interengageable tapered tongue and notch connection interposed between said arms, andmeans includment of a predetermined pressure in said outlet circuit for moving said tongue out of said notch whereby to reduce the stroke of said driven varying device connected between said elements and including a`pair of separable wedge portions having engageable surfaces inclined relatively to their direction of separation, an outlet circuit connected to said pumping device, and means responsive to the attainment of a predetermined pressure in said outlet circuit for separating said stroke-varying device whereby to reduce the stroke of said driven element.

3. In a variable-delivery pump, a reciprocable pumping device, a drivenv element connected thereto, a driving element, a separablestrokevarying device connected between said elements and including interengaging projections and recesses having mutually engageable surfaces inclined relatively to their direction of separation, an outlet circuit connected to said pumping device, and means responsive to the attainment of a predetermined pressure in said outlet circuit for separating said stroke-varying device whereby to reduce the stroke of said driven element.

4. In a variable-delivery pump, a reciprocable pumping device, a driven element connected thereto, a driving element, a separable strokevarying device connected between said elements and including interengaging projections and recesses having edges angled relatively to their longitudinal axes, an outlet circuit connected to said pumping device, and means responsive to the attainment of a predetermined pressure in said outlet circuit for separating said strokevarying device whereby to reduce the stroke of said driven element.

arm relatively to the stroke of saidA driving arm..

8.` In a variable-delivery pump, a reciprocable pumping device, means for reciprocating said pumping device, an outlet circuit connected i to said pumping device, means responsive to the.

' attainment of a predetermined pressure in said outlet circuit for reducing the stroke of said pumping device, and means including snap-action mechanism responsive to the attainment of -a predetermined temperature for abruptly raising said predetermined pressure to a higher pres sure level.

9. In a variable-delivery pump, a reciprocable pumping device, a driven element connected thereto, a driving element, a lost motion device connected between said elements, an outlet circuit connected to said pumping device, means responsive to the attainment of a predetermined pressure in sai'd outlet circuit for reducing the stroke of said pumping device. resilient means for controlling said;s predetermined pressure,v and means including snap-action mechanism connected to said resilient means and responsive to the attainment of a predetermined temperature for abruptly altering the thrust thereof whereby to abruptly raise said predetermined pressure to a higher pressure level.

10. In a variable-delivery pump, a casing. a reciprocable pumping member therein having an inlet circuit and an outlet circuit, a driving element connected to said Vpumping member, a

5.v In a variable-delivery pump, a casing, a

reciprocable pumping member therein having an. inlet circuit and an outlet circuit. a driving element connected to said pumping member, a driven element adapted to be connectedto a power source, a separable connection having a' tapered interlocking projection and recess interposed between said driving and driven elements,

means for urging said projection out of said recess to separate said connection, and means responsive to a decline below a predetermined driven element .adapted to be" connected to a` power source. a separable connection having a tapered interlocking projection and recess interposed between said driving and driven elements, means i'or urging vrsaid projection out ofsaid recess to separate said connection, means responsive to a decline below a predetermined l pressure in said outlet circuit for urging said projection into said recessl whereby to close said separable connection and increase the stroke of said pumping member, and means reponsive to .v

the attainment oi'-l a predetermined temperaa higher pressure level.

ture for raising said predetermined pressure to J. RICHARDS.

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