US2350502A - Hydraulic pump - Google Patents

Description

L. J. GARDAY HYDRAULIC PUMP June 6, 1944.

Filed Jan. 30, 1943 m ga 1.... 63944:

U ITED STATES PATENT orrlcs HYDRAULIC PUMP Application lanula'ry so, 194:, No. 474,065

4Claim8.

This invention relates to hydraulic pumps of the type having normally-closed spring-pressed suction and discharge valves adapted to open in response to pressure difl'erentials produced by the reciprocating piston or plunger of'the pump. More particularly, the invention relates to handoperated pumps for producing high pressures for testing purposes, and the inventiomhaa foran object theprovision or-improved priming means.

for pumps of this character.

Hand-operated hydraulic pumps have of course been provided heretofore for use in testing by draulic devices, such as fuel injectors and fuel injection pumps for Diesel engines, hydraulic transmission, brakes, presses, etc. Because it is often desirable to test the apparatus in its installed and operating condition, it is imperative that the test pump be compact, rugged, and as lightweight as possible, while at the same time permitting the production of high pressures. Pumps intended for the above purposes have heretofore been constructed with normally-closed spring-pressed suction and discharge valves adapted to open in response to pressure differentials produced by the piston movement and requiring no valve cams or similar valve-operating mechanisms.

Difliculties have been encountered, however, in pumps of this type due to the fact that the pump may lose its prime in various ways, or in fact the hydraulic medium may be emptied out of the pump when the pump is packed in a service kit or tool box for transportation to the job. Accordingly, when a pumping operation is attempted, alternate compression and expansion of a body of air trapped in the cylinder may occur without effecting operation of either the suction or discharge valves. Various priming expedients have been proposed, but something is yet to be desired in this connection, and accordingly it is a further object of this invention to provide a hydraulic hand pump of this character having a priming means which is inexpensive to construct,

which is highly reliable in its operation, and which does not complicate the pump construction or interfere with the normal operation of the pump after the priming has been accomplished.

In carrying out the invention in one form, a hydraulic pump of the type having a cylinder, a piston reciprocable therein, and normally-closed spring-pressed suction and discharge valves, is provided with priming means comprising a manually operable member having a portion normally spaced from the suction valve and movable theretoward to engage and positively open the suction as suitable stop pin or lug 2i which extends into the valve, so that hydraulic medium may flow therethrough and prime the pump. Spring means are provided for normally maintaining the member in spaced relation to the suction valve to insure 5 that it does not interferewith the normal pump versaw More "specifically. a pump of this character is provided with a filter unit, the interior of which communicates with the suction valve, the filter unit being surrounded bya suitable reservoirfor the-hydraulie.lmediuin. The movable member, whichnnaybe in the form of a priming rod, is slidably supported by the filter unit, with one end projecting therefrom for manual manipulation and with the other end normally spaced from the suction valve. so that when the accessible end of the priming rod is depressed the suction valve will be opened positively.

For a more complete understanding of the invention, reference should now be had to the drawing in which:

Fig. l is a perspective view of a hand-operated hydraulic testing pump em ying the present invention, the pump being shown connected for testing a fuel injector supported on a suitable test rack; and

Fig. 2 is an enlarged sectional view taken on a plane extending through or substantially parallel to the operating lever of the pump shown in 30 Fig. 1.

Referring now to the drawing, the invention is shown as embodied in a hand-operated hydraulic pump comprising a pump body ill having a base portion II, and having a central vertically ex- 35 tending bore I: which is enlarged at the lower portion of the body ill to provide a chamber l3.

Disposed within the bore I2 is a cylinder body II,

the lower end of which projects into the chamber l3, the cylinder body being provided adjacent 0 its upper end with an annular shoulder l6 adapted to rest on a corresponding inwardly extending shoulder in the bore II. A plunger or piston H is disposed in the cylinder body it, as shown, for reciprocating movement therein, and is provided at its lower extending end with a head It adapted to engage the operating lever of the pump. The piston I1 is normally maintained in its lowermost position, shown in Fig. 2, by a suitable spring I! which surrounds the extending portion of the cylinder body I, the upper end of the spring I! bearing against the upper wall of the chamber i3 and the lower end of the spring I! engaging a suitable washer 20 carried on the piston I'I. Extending from one wall of the chamber I3 is a vided with an aperture 22 adjacent the lower end thereof, and a fulcrum pin 24 extends across the apertureso as to be engageable by a correspondingly shaped notch 25 in an operating lever 25.

As shown, the inner end of an operating lever is provided with a finger 21 adapted to engage the head II on the lower end of the piston II. It will thus be clear that in order to operate the piston l1 against the force exerted by the spring l5, it is necessary only to insert the end of the operating lever 25 into the aperture 22, so that the finger 21 engages beneath the head it and the notch 25 engages the iulcrum'pin 24. Downward movement of the free end of the lever 25 will thereupon cause upward movement of the piston, and when the outer end of the lever 28 is permitted to'move upwardly the spring I! will cause the piston i'l to follow the downward movement of the inner end of the operating lever. In order to control the pumping action produced by movement or the piston II, the pump is provided with suitable suction and discharge valves of the spring-pressed normally closed type. As shown, a suitable valve, body 25 threadedly engages "in the upperend of the bore l2 in the pump l0,- and is adapted to be tightened downwardlytherein so as to compress a suitable gasket 29 between the lower surface of the valve body '28 and a suitable spring-supporting member "which rests on the upper surface of the cylinder body l4. This spring-supporting member 35 is provided with a central aperture, as shown, and supports a coil spring disposed within a hollow valve member 52 which is provided at its upper end with a plurality of ports 33. As shown, the hollow valve member 32 is disposed within avertically extending bore in the valve body 28, and the upper surface of this hollow valve is adapted to be maintained, by the spring 2|, in engagement with an annular shoulder 54 which forms a valve seat therefor.

Extending upwardly from the valve formed by the valve member 32 and the valve seat 34 is a suction passage 35 which is enlarged and threaded at its upper end to receive the core portion 36 of a suitable filter unit. This core portion, as shown, is formed to provide a longitudinally extending bore 21 intersected by a plurality of transverse passages 38, and the periphery of the core portion 36 is provided'with suitable ribs 39 for supporting a tubular filter element 40. The core portion 56 is enlarged at its opposite ends, as shown, and the respective opposite ends of the filter element 45 may besecured thereto in any desirable fashion, as for exampleby flexible bands or ties 4|. The lower end of the core portion 36 is threaded, as shown, to engage the valve body 38 and may be suitably tightened down on a gasket 42 interposed therebetween. v 1

Also supported on the valve block 28 is a reservoir 43 for containing the hydraulic medium with which the pump is to operate, and, as shown in Fig. 2, the bottom wall of the reservoir 43 includes a threaded member 44 adapted to engage suitable threads on the valve body 28. Preferably, a gasket 45 is provided for preventing leakage from the reservoir. At its upper end the reservoir 43 is provided with a neck portion 45 having a hinged closure cap '41 through which the supply of liquid medium in the reservoir may be replenished as desired.

Adjacent its upper end the cylinder body i4 is provided with a transversely extending discharge port 48 which terminates in an annuluar groove 49. Communicating with this annular groove 49 is a discharge passage 50 which extends laterally through the pump body Ill and terminates in a recess 5| in which is mounted a suitable discharge valve block 52. Slidably disposed in the valve block 52 is a hollow valve member 53 which is substantially identical with the suction valve member, and which contains a suitable spring 54. The portion of the valve block 52 which extends outwardly from the pump body II is received in a suitable recess in the gauge-supporting block 55, and in order to seal the discharge valve and the discharge passages against leakage, suitable gaskets 55 are provided on opposite sides of the valve block.

As indicated in Fig. 1, the gauge-supporting block 55 is secured to the pump body it by suitable screws 51 which extend through the block 55 and into the pump body, and it will be apparent that when these screws are tightened down the gaskets 56 will be compressed so as tightly to seal the discharge passage against leakage. The valve 53 is normally maintained in a, closed position by the spring 54, in which position the end 01' the valve member engages a suitable shoulder 58 in the valve block 52, which shoulder forms a seat for the valve member.

Communicating with the open end of the hollow valve member, and extending through the gauge-supporting block 55, is a discharge passage 59 which communicates not only with a suitable gauge 60, but also with an outlet connection 6| (Fig. 13 The details of the connections between the passage 59, the gauge 5|! and the outlet connection 5|, are omitted in order to simplify the drawing, but are entirely conventional and will be understood by those skilled in the art. I! desired-the gauge-supporting block 55 may also be provided with a suitable hand-operated valve 52 for closing oil the gauge from the discharge passage 59 when it is not desired to obtain a gauge reading of the pressure developed by the pump. Although the pump may be applied to various testing operations as previously illustrated, it is illustrated in Fig. 1 in connection with an injector nozzle 63 mounted on a suitable testing stand 64 and connected by a length oi! hollow tubing 65 to the discharge passage 5| of the pump. It will now be apparent that when the pump lever 25 is operated the piston II will reciprocate in the cylinder so as to create differential pressures by virtue of which the suction and discharge valves will be alternately opened and closed to draw fluid medium into the cylinder from the reservoir 43 on the down-stroke oi the piston, and to expel the fluid medium under pressure through the discharge valve on the up-stroke of the piston. From the-reservoir the hydraulic medium flows through the filter 45, the transverse passages 35 and the longitudinal bore 31 of the core 36, and through the passage 35, so that when the suction valve member 32 is in its open position the hydraulic medium may flow through the ports 33 and the valve member 32 into the cylinder.

As previously explained, if the cylinder initially contains a body of air, due to the fact that the pump may have been emptied for transportation purposes, or if the pump has otherwise lost its prime, reciprocation of the piston I] may be ineffective to cause opening of either the suction or discharge valves and will merely alternately compress and permit to expand the body of air contained in the cylinder. Consequently, in accordance with the present invention, the pump is provided with priming means which will not interfere with the normal operation of the pump, which requires no substantial change in the heretofore described pump filter elements, and which may be readily operated. The priming means, as shown in Fig. 2, constitutes a priming rod 10, which is provided at its upper end with an enlarged head or button H and which is mounted in the filter core portion 36 for slidable movement with respect thereto. This priming rod extends, as shown, through the bore 31 of the filter core and into the passage 35 in the valve body 28. Normally the priming rod is maintained in its uppermost position, shown in Fig. 2, by a coil spring 12 which surrounds the extending portion of the priming rod, one end of the spring bearing against the head II and the other end of the spring being contained in a suitable recess I3 in the filter core 36.

In order to prime the pump it is necessary only to open the closure cap 41 at the top of the reservoir and manually depress the priming rod Ill so that the lower end thereof will engage and positively operate the suction valve 32 to its open position. As soon as the suction valve is opened the hydraulic fluid medium will of course flow through the previously described path into the cylinder l4 so as to displace any air contained therein and effectively prime the pump.v Upon release of the priming rod it will be returned, by the spring 12, to the position shown in Fig. 2 and the suction valve 32 will of course be closed by the spring 3|. Thereafter the pump may be operated through the lever 26 in the manner heretofore described.

While I have shown particular embodiments oi. my invention, it ,will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I, therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

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

1. In a hydraulic pump of the type having a cylinder, a piston reciprocable therein, and normally-closed spring-pressed suction and discharge valves adapted for operation to their respective open positions solely by the pressure diiferentials produced by reciprocation of said piston, the combination of means for conducting hydraulic medium to the side of said suction valve opposite said cylinder, including a hollow filter unit the interior of which communicates with said valve, priming means for said pump comprising a manually operable member slidably carried by said filter unit, one end of said member being disposed in said filter unit in normal spaced relation to said suction valve and the other end of said member extending outwardly from said filter unit for manipulation to engage said one end of said member with said suction valve and eil'ect opening of said suction valve, and spring means normally maintaining said member in said normal spaced relation to said suction valve.

2. In a hydraulic pump of the type having a cylinder, a piston reciprocable therein, and normally-closed spring-pressed suction and discharge valves adapted for operation to their respective open positions solely by the pressure differentials produced by reciprocation of said piston, the combination of a hollow filter unit having an opening in one wall thereof aligned with said suction valve, passage means for connecting said opening to said cylinder through said suction valve, a reservoir for hydraulic medium surrounding said filter unit, a priming rod extending through a wall of said unit opposite said opening with one end of said rod projecting through said opening into said passage means, spring means for normally maintaining said rod in a retracted position with said one end in spaced relation to said suction valve, said rod when depressed against the force of said spring being adapted to engage and open said suction valve thereby to prime said pump with said hydraulic medium.

3. In a hydraulic pump, a pump body having a vertically extending cylinder therein, a piston reciprocable in said cylinder, means forming suction and discharge passages communicating with said cylinder, normally-closed spring-pressed suction and discharge valves in said respective passages adapted to open in response to pressure difierentials produced by reciprocation of said piston, said suction valve being disposed above said cylinder for vertical movement axially of said suction passage, filter means disposed above said suction valve including a supporting core portion mounted in said means forming said suction passage and having a bore extending in alignment with said suction passage, a reservoir for hydraulic medium surrounding said filter means for supplying said medium to said bore and suction passage, a priming rod mounted in said core for slidable movement axially of said bore and suction passage, and spring means normally biasing said rod to an upper position wherein the lower end of said rod is spaced from said suction valve, said rod being depress ble to engage and forcibly open said suction valve thereby to prime said pump.

4. In a hydraulic pump, a pump body having a vertically extending cylinder therein, a piston reciprocable in said cylinder, means forming suction and discharge passages communicating with said cylinder, normally-closed spring-pressed suction and discharge valves in said respective passages adapted to open in response to pressure diii'erentials produced by reciprocation of said piston, said suction valve being disposed above said cylinder for vertical movement axially 01' said suction passage, filter means disposed above said suction valve including a supporting core portion mounted in said means forming said suction passage and having a bore extending in alignment with said suction passage, a reservoir for hydraulic medium surrounding said filter means for supplying said medium to said bore and suction passage. a priming rod mounted in said core forslidable movement axially or said bore and suction passage, one end of said rod extending beyond said core portion and having an enlarged head thereon, and spring means interposed between the end of said core portion and said head for normally maintaining said rod in an upper position wherein the other end of said rod is spaced from said suction valve. said rod being depressible' against the bias of said spring to a lower position' wherein said other end of said rod engages and positively opens said suction valve to prime said pump with filtered hydraulic medium irom said reservoir.

LOUIS J. GARDAY.

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