US3002461A - Variable capacity pump - Google Patents

Description

w. R. EAMES, JR

VARIABLE CAPACITYPUMP Oct. 3, 1961 Filed Aug. 15, 195.6

2 Sheets-Sheet l Fig] INVENTO WALTER R. EAME v MM f7.4

A TTORNE YS Oct. 3, 1961 w. R. EAMES, JR

VARIABLE CAPACITY PUMP 2 Sheets-Sheet 2 Filed Aug. 13, 1956 INVENTOR. WALTER R. EAMES JR.

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A TTORNE YS United States Patent O 3,002,461 VARIABLE CAPACITY PUMP Walter R. Eames, Jr., Royal Oak, Mich., assignor to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Filed Aug. 13, 1956, Ser. No. 603,581 Claims. (Cl. 10S- 11) In many applications requiring pressurized hydraulic fluid to perform work in a hydraulic circuit, the volume requirements vary greatly. To satisfy the demand in such a system, a variable capacity pump is ordinarily used. This results in a pump which, by necessity, is more complicated than a constant displacement type pump.

This invention relates to the accomplishment of the :function of a variable displacement type pump by using la constant displacement pump with a novel valving arrangement.

An object of this invention is to provide a constant displacement pump with a novel valvingarrangement to replace a variable displacement pump.

A further object is to provide a pump having multiple pumping strokes per pump cycle.

These and other objects and advantages will become more yapparent from the following detailed description of the device and from the accompanying drawings.

FIGURE 1 schematically illustrates a pump and novel control Itherefor.

FIGURE 2 shows the control illustrated in FIGURE l in a dilierent operating position.

FIGURE 3 is a modiiication of the control system.

FIGURE 4 illustrates the modication shown in FIG- URE 3 in a diiierent operating position.

This device is comprised of a lluid control system corn-v prising a single pump having at least two pumping chambers ot equal or unequal capacity, depending upon the particular application of the structure or of a plurality ot pumps having single or multiple pumping chambers with equal or unequal capacity, depending upon the application of the structure. For convenience, the device will be described utilizing a single pump with two pumping chambers of unequal capacity. The pumping chambers are in communication with a -fluid reservoir which provides the necessary supply of oil to the pump. In a structure utilizing two pumping chambers, the communication between the reservoir and one of the chambers is provided with :a check valve which allows flow to the chamber from the reservoir but prevents reverse flow and this lirst chamber is also provided with a dischargecommunication to an out-put line. The second pumping chamber is provided with similar communicating lines to the reservoir and the output line except that there is no check valve provided in the intake line ttor the second chamber. A valve means is provided having a plunger which is connected to the discharge from bot-h chambers in the output line, tendingto move the valve in one direction, and spring means opposing this iiuid force. When the valve plunger is longitudinally moved a'certain IamountV in response to fluid pressure, the output from bothl o-f said pump chambers is communicated by a `first bypass line means to the intake of the hist mentioned `plump chamber. When the valve -plunger is moved further in the same direction, the combined output of the pump is communicated to the intake of both of said pump chambers by said ii-rstbypass line anda second bypass line connected to said valve and said second mentioned pump chamber. The bypass return tlow i-n the iirst mentioned line is prevented from returningto the reservoir by the, previously mentioned check valve. Therefore,`when the valve is moved so that the lirst bypass Lline and at least a pontion of the second bypassline are incominunic'atdn with' the' combined outputl of the ICC pump, a volume equal to the output of the iirst chamber is merely shunted back to the first chamber with no resulting loss of work except -for irictional line losses. When the pump output is decreased or the output requirement is increased, the valve is closed in response to the diiferential of the spring torce and reduced discharge pressure and the Ifull capacity of the pump is discharged to the output line. If for any reason the output requirement is greatly diminished or the pump output is greatly increased, the pressure in the output line increases and the valve is completely opened which results in a bypass of the Afull capacity of the pump back to the pumping chambers. A communication is provided between the wonk performing device and the reservoir to provide a return for the fluid.

It is to be noted that a pump having more than two pumping chambers can be utilized. Ii, Ifor example, a unit having four pumping chambers is used and it is desired to be able to motor one, two, o-r three of the. chambers, check valves are placed in the communicating lines between the reservoir and the intake means to each of the chambers to be motored to prevent flow of uid back to the reservoir.

Referring to the drawing for a more detailed description of the invention, the iluid device 10 4is provided with a rotary pump 12 having a rotor 14 and a housing 16. A rotary pump is illustrated but the invention is not limited to this type pumping structure. A pressure relief valve .18 communicates with the discharge and inrta'ke of the pump 12 in a manner which will be described in detail in the following description.

The pump 12 is provided with a relatively large ca pacity chamber 20 and a smaller capacity chamber 22. A reservoir 24 furnishes fluid to the high capacity pump chamber by'means of fluid conduits 26, 28, and 30. A check valve 32 is interposed in conduit 28 which allows lflow Ifrom the large capacity chamber to the reservoir and -t-he small capacity chamber is furnished with fluid from the reservoir by means of lluid conduits 26, 34, and 36. The valve 18 is provided with a pair of bypass ports, 318 and `40, the port 38 communicating with the conduit 36 by means of a conduit 412 and bypass port 40 communicating with lconduit 30 by means ot conduit 44.

A conduit 46 is connected at one end to the discharge side of the low capacity chamber 22 and is connected at the other end to chamber 48 of valve 18.. A conduit 50 is connected at one end to the discharge of the high capacity chamber 20 and at the other end to the conduit 46 so that the :discharge `from both the large capacity and the small capacity chambers is communicated to the valve chamber `48. The remainder of the valve structure 18 is comprised of a piston 52 having an end portion in communication with the chamber 48 `and a compression spring 54 acting against the piston 52 yand reacting against an adjustable plug 56. An output port 58 is connected to the chamber 48 of valve 18 and provides acomrnunication between the control system 10 and the working system (notshown). Obviously, the output por-t can be located at any point in the discharge conduit 46 and is shown formed vin vthe valve housing merely for a convenience and is not "limited to the exact location shown in the drawing. Also, there is a communication between the Vexhaust side of the working system and the reservoir `to provide a return'means for uid to the reservoir. The

`wise direction, fluid from the sump is communicated both to the large capacity chamber and the small capacity chamber. Fluid under pressure is then discharged into the conduits 46 and 50 which jointly communicate with thvalve chamber 48 and thence to the output port 58.

When the discharge requirements to the working system are such that the full output pressure of the pump is required, the piston 52 of control valve 18 will remain in the position shown in FIGURE 1. At this time, the total pressure of the low capacity and high capacity chamber is directly communicated to the output port 58 with no bypass of pressure from either of the working chambers back to the pump. When the discharge requirements are decreased or there is a substantial increase in pump flow, a pressure rise in the discharge line and in the chamber 48 results in the movement of piston 52 of valve 18 to a position wherein `the bypass port 40 is uncovered. The combined pump discharge is now in communication with both the output conduit 58 and the bypass conduit 44 which bypasses a portion of the output of the combined pump discharge back to the large capacity chamber. At this time, there is no motoring effect but when the requirements are lagain reduced until piston 52 moves to a position establishing at least a partial communication between output conduit 58 and bypass conduit 42, the discharge from the large capacity chamber is bypassed or recirculated back to the large capacity chamber resulting in a motoring of the large capacity chamber. Under this operating condition, the high capacity chamber is in a motoring condition, but most irnportant, this motoring does not result in any power loss except for line losses, since the discharge from the large capacity chamber is communicated back to the intake side of the large capacity chamber. If the discharge requirement falls below a predetermined minimum, the piston 52 moves further upward, as shown in FIGURE 2, resulting in greater communication of the bypass port 38 with the chamber 48. Consequently, the total discharge of the high capacity chamber and a portion of the discharge of the low capacity chamber, less line losses, is bypassed back to the intake of both chambers of the pump with `the high capacity chamber being motored and the remaining portion of the low capacity chamber output, less line losses, being returned to the low capacity chamber input and the reservoir.

*FIGURE 3 illustrates a modification of the control valve. A valve 118 is provided with a valve body 155, a piston 152, a compression spring 154 interposed between the piston 152 and the adjustable plug 156 and a pair of bypass ports 138 and 140 communicating by conduit means with the low and high capacity chambers, respectively. An orice 160 is provided in the piston 152 so that fluid flow from the discharge side of the large capacity chamber and the small capacity chamber flows through the orifice into the discharge conduit 158. This modied structure operates in the following manner.

When the pump rotor is rotated, iiuid from the reservoir 124 is communicated to both the large capacity chamber 120 and the small capacity chamber 122. Fluid under pressure is then discharged into the discharge conduits 146 and 150 which communicate with the valve chamber 148, orilice 160, and the discharge conduit 158.

When the iiow requirements to the system are such that the discharge of the pump does not exceed those requirements, piston 152 of the control valve 118 will remain in the position shown in FIGURE 3. At this time, the combined iiow of the small capacity chamber and the large capacity chamber is directly communicated to the output conduit 158 and there is a maximum permissible pressure drop across orifice 160 with no bypass of uid from either of the working chambers back to the pump. When the discharge of the pump is increased above the requirements of the working system or the requirements of the working system are reduced, How across the oriiice is increased and there is a consequent increase in pressure drop across the orifice which results in a movement of the valve to a position in which bypass port 140 is uncovered. The combined pump discharge is now in communication with both the output conduit 58 and the bypass port 140 which results in a bypass of a portion of the output of the combined pump discharge back to the large capacity chamber. At this time, there is no motoring but when the flow requirements are again reduced until piston 152 moves to a position establishing at least a partial communication between output conduit 158 and bypass conduit 142, the discharge from the large capacity chamber is bypassed or recirculated back to the large capacity chamber with no resulting loss of work except for frictional line losses. VUnder this condition, the large capacity chamber is motoring. It is obvious therefore, that this modification of the device is responsive to ow rather than being pressure responsive. If the discharge of the pump increases further, piston 152 of valve 118 moves further upwardly (as viewed in FIG- URE 4) resulting in greater communication of bypass port 138 with the output conduit. Consequently, an increased quantity of flow `from the pump is bypassed to the intake of the low capacity chamber of the pump.

It is obvious that the ratio of the capacity of the large capacity chamber and the small capacity chamber can be varied to obtain any percentage of reduction in fiow that is desired. For example, in use in a transmission, a small basic flow is required for leakage and a much higher flow is necessary when effecting the movement of one or more clutches. In such an application, the structure disclosed herein would shift into high range to lill the clutch rapidly and then drop to low range to merely held the pressure.

Also, as previously mentioned, more than two pumping chambers can be utilized and a device having two chambers has been illustrated merely for purposes of clarity and simplicity.

The structure disclosed herein describes a iiuid control system comprising a pump having at least two pumping chambers or a structure having a plurality of pumps with each pump having single or multiple pumping chambers wherein control means is provided to allow selective cornmunication of the combined discharge of said pump or pumps with the inlet of one or more of said pumping chambers.

This control can be either pressure responsive or tlow responsive, depending upon the particular application which is required.

While the present invention has been described in connection with certain specific embodiments, it is to be understood that Ithe foregoing description is merely exemplary and that the concept of this invention is susceptible of numerous other modifications, variations, and applications which will be apparent to persons skilled in the art. The invention is to be limited, therefore, only by the broad scope of the appended claims.

I claim:

l. A uid control system comprising means having a plurality of fiuid pumping chambers, a single pressure responsive valve, a work communicating means, each of said pumping chambers being provided with an intake means and 'a discharge means, said intake means being in uid communication with said valve and said discharge means Vbeing in iiuid communication with said valve and said work communicating means, means in said valve being movable in response to the combined pressure of the fluid discharge of said pumping chambers and being movable to a position to allow iiuid communication between said discharge means andA one or more of said in- Itake means, one-way valve means interposed between said one or :more intake means and the remaining of said intake means preventing fluid How from said one or more of said intake means to the remaining of said intake means, whereby at least a portion of said fluid discharge from said pumping chambers is bypassed to said one or more of said intake means.

2. A pumping device comprising la pump having a low capacity pumping chamber and a high capacity pumping chamber, each of said pumping chambers having an intake means and a discharge means, a iiuid reservoir in uid communication with said intake means of said pumping chambers, check valve means interposed between at least one of said intake means of said pumping chambers and the remaining intake means of the remaining pumping chambers to prevent flow of tluid from said one intake means to said remaining intake means, a single control valve, said intake and said discharge means of said pumping chambers being in iluid communication with said control valve, means `in said control valve to allow uid communication between said `discharge means and said one intake means, and a Work outlet chamber in iluid communication with said discharge means of said pumping chambers.

3. A iluid pump means comprising a multiplicity of pumping chambers, each of said pumping chambers having an intake means and a discharge means, a single control valve, said intake means and said discharge means communicating with said valve, a work outlet means in fluid communication with said discharge means, ow responsive means in said valve to selectively prevent uid communication between said intake means 'and said discharge means and -to -allow selective uid communication between one or more of said intake means and said discharge means upon a su'icient increase in fluid flow in said valve, and one-Way valve means interposed between said one or more intake means and the remaining of said intake means preventing tluid ow from said one or more of said intake means to the remaining of said intake means.

4. A uid control system comprising means having a plurality of pumping chambers, each of said pumping chambers having an inlet means Iand a discharge means, reservoir means in fluid communication with said inlet means, one-Way valve means interposed between said one or more inlet means land the remaining of said inlet means to prevent ow from said one or more of said inlet means to the remaining of said inlet means and to said reservoir, a single control valve i-n uid communication with said discharge means and pressure responsive means in said valve to selectively communicate said discharge means with one or more of said inlet means.

5. A tluid control system comprising means having a plurality of pumping chambers, each of said pumping chambers having an inlet means and la dis-charge means, reservoir means in uid communication with said inlet means, one-way valve means interposed between said one or more inlet means and the remaining of said inlet means to prevent ow from said one or more of said inlet means to the remaining of said inlet means and to said reservoir, a single control valve in uid communication with said discharge means and ow responsive means in said valve to selectively communicate said discharge means `with one or more of said inlet means.

References Cited in the tile of this patent UNITED STATES PATENTS 1,814,857 Rosle July 14, 1931 2,377,556 Jeannin June 5, 1945 2,401,567 Jeannin June 4, 1946 2,599,701 Eames June 10, 1952 2,780,172 Coar Feb. 5, 1957 2,878,753 Adams et al Mar. 24, 1959 2,887,060 Adams et al May 19, 1959 FOREIGN PATENTS 559,108 Great Britain Feb. 4, 1944 712,796 Germany Oct. 25, 1941 1,108,743 France Iune 17, 1954

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