US3415194A

US3415194A - Pump

Info

Publication number: US3415194A
Application number: US579930A
Authority: US
Inventors: Lavern R Connelly
Original assignee: Eaton Yale and Towne Inc
Current assignee: Eaton Corp
Priority date: 1966-09-16
Filing date: 1966-09-16
Publication date: 1968-12-10
Anticipated expiration: 1985-12-10
Also published as: SE323288B; DE1653844A1; DK136876C; NO120967B; CH482117A; DK136876B; DE1653844B2; DE1653844C3; ES345101A1; GB1201389A

Description

Dec. l0, 1968 Filed Sept. 16, 1966 L.. R. CONNELLY PUMP 3 Sheets-Sheet l I Il' e www@ ATTORNEYS Dec. 10, 1968 R, CONNELLY 3,415,194

PUMP

3 Sheets-Sheet 2 Filed Sept. 16, 1966 w d 4 Y w mw M m90 vA l a x WR m6 n /6 M l /f/ w w m M t@ m. l ll mm M w mi@ f w 0 84 @ma L/ 5, a H

w F 0 m w ATTQl/SNE YS Dec. 10, 1968 Filed Sept. 16, 1966 L. R. CONNELLY PUMP 5 Sheets-Sheet 3 LAVEEN R. COA/NELLY United States Patent O 3,415,194 PUMP Lavern R. Connelly, Marshall, Mich., assignor to Eaton Yale & Towne Inc., Cleveland, Ohio, a corporation of Ohio Filed Sept. 16, 1966, Ser. No. 579,930 17 Claims. (Cl. 103-41) ABSTRACT OF THE DISCLOSURE The present invention relates to a pump, and more particularly relates to a pump having flow control means associated therewith for controlling the flow of discharge fluid from the pump to a fluid system.

A pump embodying vthe present invention may be utilized in a hydraulic power steering system in an automotive vehicle, or the like and is particularly adapted for such use. Such known pumps include a pump housing containing ya pumping means having a fluid discharge for directing fluid to the system and an inlet for receiving flow from the system. The known pumps also include a flow control valve means which operates to bypass a portion of the fluid discharged from the pumping means to the inlet of the pumping means and thereby controls the amount of fluid which is directed from the pump.

An object of the present invention is the provision of a new and improved pump for supplying fluid to an external fluid system and having flow control means associated therewith for controlling the flow of fluid discharged from the pump to the system by bypassing discharged fluid to the pump inlet, and wherein the flow control means is operable to provide a decreasing amount of fluid flow to the system as pump speed increases above a predetermined speed and provides an increased amount of fluid flow to the system at pump speeds above the predetermined speed when system pressure increases.

Another object of the present invention is the provision of a new and improved pump for supplying fluid to a fluid system including pumping means having flow control means associated therewith to control the amount of fluid directed to the system by bypassing a portion of the fluid discharged from the pumping means to an inlet of the pumping means, and wherein the flow control means is constructed so as to bypass the fluid at a substantial velocity.

Another object of the present invention is the provision of a new and improved pump, as noted in the next preceding paragraph, wherein the flow control means includes a valve member having a surface portion which directs the bypassed fluid inwardly of the valve and has a flared end portion which then directs the fluid outwardly of the valve.

Another object of the present invention is the provision of a new and improved pump, as set forth in the next preceding paragraph, and wherein the high velocity bypassed fluid is directed toward the inlet of the pumping means so that a low pressure `region is created adjacent an inlet of the pump to draw fluid from the system into the pumping means.

A further object of the present invention is the provision of a new and improved pump operable -to supply fluid to ICC a fluid system and including inlet and discharge passageways communicating with the system, flow control means operable to control the amount of discharge fluid flowing to the system and including a valve member movable to bypass fluid from the discharge passageway to the inlet passageway in response to a pressure differential acting thereon, and wherein the pressure differential is created at least in part by the action of a flow restricting orifice in the form of a groove formed in the valve member and which variably restricts fluid ilow therethrough in response to movement of the valve member.

Yet `another object of the present invention is the provision of a new and improved pump for supplying fluid to a fluid system including pumping means having inlet and discharge passageways communicating with the system and llow control means operable to control the amount of fluid supplied by -the pump to the system, `the flow control means including a valve member movable to bypass fluid from the discharge passageway to the inlet passageway to reduce the flow of fluid to the system, and wherein the valve member has an opening therethrough between the inlet passageway and a fluid reservoir so that fluid flows from the reservoir into the inlet passageway therethrough.

Another object of the present invention is the provision of a new and improved pump, as set forth in the next preceding paragraph and in which the valve member is movably disposed in a bore defining a fluid chamber with pressure in the chamber acting on a portion of the valve member and tending to move the v-alve member, and wherein a relief valve means opens to direct fluid from the chamber to the reservoir when fluid pressure in the chamber is above a predetermined pressure.

Further objects and advantages of the present invention will `be apparent to those skilled in the art to which it relates from the following detailed description thereof made with reference tothe accompanying drawings forming a part of this specification and in which:

FIG. l is -a sectional view of a pump embodying the present invention;

FIG. 2 is a section view of a modified pump embodying the present invention with portions thereof shown in elevation;

FIG. 3 is a sectional view of a further modified pump embodying the present invention and having parts thereof shown in elevation;

FIG. 4 is a fragmentary sectional view of a portion of the pump shown in FIG. 3;

FIG. 5 is a fragmentary sectional view of a portion of the pump shown in FIG. l;

FIG. 6 is a sectional view of a further modified structure for use in a fluid pump; and

FIG. 7 is a sectional View of the portion of the pump shown in FIG. 4 in a different operative condition.

A pump 10 embodying the present invention is particularly suited for use in a hydraulically operated automotive power steering system and has been described in conjunction with such a system which has been illustrated schematically in the drawings. However, it will become apparent from the following description that a pump emmodying the present invention is suitable for use in many environments.

As shown in FIG. 1, the pump 10 includes a housing 11, pumping means 12, and a driving shaft 13 extending into the housing 11 and drivingly connected to the pumping Vmeans 12. The shaft 13 is adapted to be driven from an 1engine of the vehicle, not shown, at speeds which vary with the engine speed. The pumping means 12 is prefera- Ibly a rotary pump and, as illustrated, includes a rotor `member 12a which is secured to the shaft 13 for rotation therewith. The rotor member includes a plurality of radially extending grooves or slots therein which carry cylindrical pumping elements 12b. A cam member 12o surrounds the pumping rotor and includes a cam surface upon which the pumping elements 12b are moved by the rotor as the rotor is rotated by the shaft 13. The cam surface is so configured that the pumping elements 12b are moved radially relative to the rotor member 12a during a revolution thereof. Radial movement of the pumping elements 12b relative to the rotor member 12a effects pumping of fluid in a manner which is well known. The cam surface of the cam member 12C may be configured to provide any number of pumping strokes of the pumping elements. In the preferred embodiment, two such pumping strokes are provided for.

A cover member is positioned in the housing 11 adjacent the pumping means 12 at an axial side thereof. The cover member 15 includes a pair of discharge charnbers 14, only one of which is illustrated, and which are spaced approximately 180 degrees apart in the cover member 15. The discharge chambers 14 open into a planar surface 15a adjacent the pumping means 12 to provide discharge ports 15b for the pumping means 12. The discharge chambers 14 communicates with the discharge ports 15a and with the fluid system through a discharge passage 17. The cover member 1S also includes a pair of inlet chambers 14a which are spaced approximately 180 degrees apart therein and which open into the surface 15a to provide inlet ports 15C for the pumping means 12.

The inlet chambers 14a communicate with the inlet ports 15C and with a fluid reservoir 21 of the system. The cover member 15 additionally includes a central portion which forms a support for a suitable bearing 18. The bearing 18 rotatably supports an end of the shaft 13 in the cover member 15.

The pumping means 12 is positioned in the housing 11 between the cover member 15 and an end plate member 30. The end plate member 30 is fixed in the housing by means of screws, not shown, which extend through the end plate member, the cam member and are threadedly engaged in the cover member 15. The end plate member 30 includes a body portion 30a and a flange portion 30b. The body portion 30a surrounds the shaft 13 and provides a support for a bearing 30C which rotatably supports the shaft. The body portion 30a additionally is associated with siutable seals to prevent leakage of fluid between the body portion and the housing 11 and shaft 13, respectively.

The flange portion 30b includes a planar surface 30d adjacent the pumping means 12 and which includes grooves or chambers therein which form discharge ports 30e for the pumping means 12 and which communicate with the discharge chambers 14. The discharge ports 30e in the end plate are spaced apart approximately 180 degrees in the end plate member and are located in registry with the discharge chambers 14. The flange portion 30b also includes grooves or chamber which form inlet ports 30]c for the pumping means 12. The inlet ports 30f communicate with the inlet chambers 14a in the cover member 15 by conduit means which extend therebetween. The conduit means includes a central flow passage in the shaft 13 which opens into the inlet chamber 14a at the end of the shaft 13 supported in the cover member 15. The passage 25 communicates with the inlet ports 30j in the end plate through ports 26 extending between the passage 25 and the outer periphery of the shaft, and a flow passage 27 in the end plate which is operable to direct fluid from the ports 26 into the pumping means 12 through the inlet ports 30f.

The operation of the pump 10 should be apparent from the foregoing description. The rotor member 12a is rotated by the shaft 13 to effect pumping of the fluid. Fluid at discharge pressure of the pump flows into the discharge chamber 14 and is directed therefrom to the power steering system through the discharge passage 17. Fluid which has traversed the system is returned therefrom to the fluid reservoir 21 and into the inlet chambers 14a in the cover member 15. Fluid in the inlet chambers 14a is directed to the pumping means 12 through the inlet ports in the cover member 15 and through the passage 2S in the shaft 13 and to the inlet ports in the end plate 30. The pumping means 12 is of the positive displacement type and it should be apparent that the quantity of fluid pumped thereby in the manner described depends on the rotational speed of the pumping rotor member 12a as controlled by the vehicle engine speed.

In acordance with the present invention, flow control means 16 is provided for controlling the amount of fluid flowing from the pumping means 12 to the system. The flow control means 16 is operable to bypass fluid from the discharge chamber 14 to the inlet chamber 14a and thereby reduce the quantity of fluid directed to the fluid system. As shown in FIG. l, the flow control means 16 includes a bore 32 in the cover member 15 opening at its opposite ends into the inlet chamber 14a and the reservoir 21. The bore 32 also includes openings therein communicating with the discharge chamber 14 and the discharge fitting 17 leading to the fluid system. A valve member 33 is slidably supported in the bore 32 and is movable axially therein in response to differential fluid pressure forces acting thereon to bypass fluid from the discharge chamber to the inlet chamber to provide a controlled amount of fluid flow to the system.

As shown in the drawings, the valve member 33 includes a generally cylindrical portion 41 at the end thereof adjacent the inlet chamber 14a and which has a diametrical extent slightly less than the diametrical extent of the bore 32. The valve member 33 also includes a land portion 42 spaced from the aforementioned cylindrical portion 41 to provide an annular chamber 43 therebetween. The land portion 42 is provided with a plurality of grooves to effect a seal between the valve member 33 and the bore 32, as well as to provide a floating relationship between valve member 33 and the bore 32. The valve member 33 additionally includes an end portion 45 extending from the land portion 42 toward the reservoir 21 which is of smaller diametrical extent than the l'and portion 42. The end portion 45 includes a plurality of sealing grooves adjacent its right-hand end, as viewed in the drawing, and which are effective to form a seal between the end 45 of the valve member 33 and a cylindrical opening 46 at the end of the bore adjacent the reservoir 21, as well as to float the valve member in the opening 46. The opening 46 is of a diametrical extent which is smaller than that of the bore 32. Spring means 47 acts between the land 42 of the valve member 33 and a shoulder 50 formed by the juncture of the bore 32 at the opening 46. The spring means 47 is effective to urge the valve member 33 to the left, as viewed in the drawings, and urges an end portion 40 of the valve member 33 into sealing engagement with a valve seat 51 fixed in the bore 32 between the discharge chamber 14 and the inlet chambers 14a.

When the valve member 33 is in its position shown in FIG. l, fluid flowing from the discharge chamber 14 lof the pump passes in a restricted manner through a controlled flow orifice 52 formed by the cylindrical portion 41 of the valve member 33 and the periphery of the bore 32. Since discharge fluid flowing to the system traverses this Orifice, it may be referred to as the primary flow controlling orifice or primary orifice. Fluid flowing through the primary orifice 52 is directed to the fluid system through the fluid discharge passage 17. Fluid which passes through the orifice 52 and into the annular chamber 43, formed between the portion 41 and the Iland 42 of the valve member, experiences a pressure drop so that the pressure in the chamber 43 is lower than that of the fluid in the pump discharge chambers 14. The chamber 43 is in fluid communication with a chamber 54 formed between lthe end 45 of the valve and the bore 32 by means of a flow passage 55 in the valve member 33 and which communicates with the

chambers

43, 54 by way of ports 56, S7.

When the valve member 33 is in its position shown in FIG. 1, and the pump is operating at fairly low speed, fluid discharged from the pumping means 12 into the discharge chamber 14 is directed to the fluid system through the discharge passage 17. At a given system pressure, and as pumping speeds increase, the amount of fluid flowing to the system increases, as noted above. At a predetermined pump speed, the pressure differential across the valve member is effective to shift the valve member toward the right, as viewed in the drawings, such that the end 40 thereof is moved out of sealing engagement with the valve seat 51. When the valve member 33 moves to the right, as described, against the bias of the spring means 47, fluid from the discharge chamber 14 flows between the end 40 of the valve member 33 and the valve seat 51 and is bypassed from the system to the inlet chamber 14a. As pump speeds continue to increase above the predetermined speed, greater quantities of discharge fluid are bypassed and a lesser amount of fluid flows to the system. The characteristic of decreasing ow as pump speed increases above a predetermined speed is referred to as flow droop.

The ow controll means 16 includes nozzle means for directing bypass fluid inwardly of the valve member and into the inlet chamber of the pump at a substantial velocity to conserve the energy of the liuid bypassed and reduce system temperatures accordingly. The nozzle means includes a frusto-conical peripheral portion 40a at the end 40 of the valve member 33. Fluid flowing from the discharge chamber 14 to the inlet chamber 14a is directed through an opening formed by the frustoconical periphery 40a of the valve member 33 and the valve set 51 when the valve member is in a bypass posi tion. The frusto-conical portion 40a and the valve seat 51 cooperate to form a Venturi effect. When the valve member moves as described, fluid is bypassed between the portion 40a and the valve seat 51 to provide the aformentioned flow droop. The amount of droop in flow for a particular pump is controlled by the angle of the frusto-conical portion 40a with droop increasing as the included angle of the portion 40a is increased.

The high velocity fluid owing between the valve 33 and the valve seat 51 is directed into the inlet chamber 14a in the cover 15 and into the passageway 25 formed in the shaft 13, from which it is delivered to the inlet ports 307 in the end plate 30 through the passages 26, 27. It should be apparent that the bypassing of iiuid effected by the valve 33, as described, is extremely efiicient and that recovery of the pressure of the discharged fluid is effected as the velocity of the fluid bypassed is reduced in the inlet of the pumping means. This recovery of the pressure is effective to minimize temperature rises of the uid in the system which might otherwise occur if the fluid were bypassed in a restricted manner with a large pressure loss.

The pump is constructed so that the high velocity bypass uid is utilized to draw uid into the inlet chambers 14a from the reservoir 21. As illustrated in FIG. 1, the cover member 15 is provided with a ledge 60 adjacent a port 23 between the reservoir 21 and the inlet chambers 14a. The ledge 60, port 23, and the valve member 33 are associated so that when high velocity bypass uid flows past the ledge 60, a low pressure area is developed in the inlet chamber 14a adjacent the port 23. This low pressure region in the inlet chamber 23 is created due to the high velocity of the bypassed uid and causes uid' in the reservoir 21 to be drawn through the port 23 and into the inlet chamber 22. This operation of the valve member 33 may be termed supercharging, since the fluid in the reservoir 21 is urged into the pump inlet and is a result of utilization of the energy of the bypass fluid.

When uid is being bypassed and the system pressure increases, as when uid is required by the system, the flow control means 16 effects an increase in the ow of uid to the system. Increases in the system pressure result in increased pressure in the chamber 54 which urges the valve member 33 toward the left, as viewed in the drawings. Movement of the valve member 33 to the left reduces the amount of fluid being bypassed and thus increases the amount of fluid flowing to the system to satisfy system fluid requirements at pump speeds above the predetermined pump speed. It should be apparent that the ow control means is effective to pnovide a droop in the quantity of fluid owing to the system and is also operable to increase the ow of uid to the system When system ui'd requirements increase.

In the event that uid pressure in the system should exceed a predetermined pressure, relief valve means 61, carried by the valve member 33, opens to communicate fluid in the chamber 54 with the reservoir 21 through the port 57 and passage 55 thereby reducing pressure in the chamber 54 and effecting movement of the valve member 33 to the right, as viewed in the drawings, to bypass additional uid from the system. As shown in the drawings, the relief valve means 61 includes a check ball 62 positioned in a passage in the valve member 33 and which is biased to a closed position by a spring means 63. The spring means 63 acts between a reaction ball member 64 and the check ball 62 and yields at a predetermined pressure to provide for opening of the check valve means 61 to provide for a reduction of uid pressure in the chamber 54 by communicating the chamber 54 with the reservoir 21 through the port 57 and valve 61, permitting discharge uid to ow from the chamber 43 to the reservoir 21 through the port 56 and the valve 61. The system pressure therefore is controlled by the relief vallve means 61 subsequent to opening thereof.

Operation of the pump 10 and ow control means 16 should be apparent from the foregoing description. When the pumping means 12 is stopped or pumping at low rates, the valve 33 is in its condition shown in FIG. 1 and uid which is discharged from the pumping means 12 is delivered to the Huid system by way of the discharge chambers 14, primary orilice 52 and discharge passage 17. At a given system pressure, and as -pump speed increases, How rates from the pump increase, and the pressure forces in the discharge chamber 14 acting on the valve 33 toward the right increase at a rate which is greater than the increase in the pressure force acting toward the left on the valve member 33. At a predetermined pump speed, the pressure forces produced by the uid in the discharge chambers 14 overcome the opposing pressure forces acting on the valve member 33 and the force of the spring 47 to move the valve member 33 to the right, as viewed in the drawings. When the valve member 33 is moved to the right, the portion 40a thereof is moved away from the valve seat 51 to produce the nozzle-like passageway between the discharge chambers 14 and the inlet chambers 14a.

Fluid owing between the discharge chambers 14 and the inlet chambers 14a is bypassed through the nozzle-like opening at relatively high velocities and with a minimum of pressure loss. The fluid traversing the aforementioned nozzle is directed into the inlet of the pumping means by way of the aforementioned inlet ports in the cover member and end plate. Additionally, the high velocity uid creates a low pressure region to the left of the valve member 33, as viewed in the drawings, and which low pressure region is effective to induce a flow of fluid from the reservoir 21 through the port 23 and into the inlet chamber 14a.

The valve member 33 moves toward the right, as viewed in the drawings, until the pressure acting thereon from the discharge chamber 14 is balanced by the opposing pressure and spring forces. Balancing of these forces occurs at a position of the valve member wherein a given amount of discharge uid is being bypassed to the inlet chamber 14a. Further increases in pump speed will result in the valve member 33 being moved further to the right until the forces acting on the valve member are again balanced and with a still further increase inthe amount of fluid bypassed from the discharge chamber 14 to the inlet chamber 14a to produce the aforementioned flow droop.

When the system pressure increases at a given pump speed above the predetermined speed, the valve member moves to increase the amount of fluid flowing to the system to satisfy system fluid requirements.

When the system pressure increases above a predetermined pressure, the relief valve means 61 in the valve member 33 cracks resulting in additional bypassing of fluid from the system and controlling of the system pressure.

Referring to FIG. 6, a modified valve member is shown. The valve member 75 is similar in configuration to the valve member 33 previously described, but includes a flow restricting passageway 76 which extends between the discharge chamber of the pump and a chamber 77 formed between a land portion 78 and the cylindrical portion 79 of the valve member. The passageway 76 forms the primary orifice of the flow control means in this embodiment and, therefore, the land 78 and cylindrical portion 79 are of the same diameter. The chamber 77 is in fluid communication with a check valve means 80 positioned in the valve member by way of a fluid passageway 81 extending therebetween. At a predetermined pressure in the passageway 81, which is a function of the system pressure, the check valve means 80 opens to bypass fluid from the discharge chamber of the pump to the reservoir thereof. Operation of the flow control means 16 including the valve member 75 is substantially the same as described previously in reference to FIG. 1.

Referring to FIG. 3, a modified pump embodying the -present invention is shown. The pump 100 is connected in the fluid system, as dccribed above, to provide for circulation of fluid therethrough. The pump 100 includes a housing 111 containing a pumping means 112 drivingly connected to a shaft means 113 for rotation therewith. The pumping means 112 is supported between a cover member 115 and an end plate, not shown, which are fixed in the housing 111. The construction of the aforementioned parts of the pump 100 is substantially the same as that described in reference to FIG. 1 and, therefore, the construction of these parts will not be further described in detail. The pump 100 also includes a flow control means 101 which is effective to control the flow of fluid from a discharge chamber 114 of the pump to the external system by bypassing fluid from the discharge chamber 114 to an inlet chamber 122 of the pump in a highly efficient manner.

The inlet chamber 122 of the pump is in fluid communication with an inlet of the lpumping means 112 directly from the chamber 122, and through a central opening 125 in the drive shaft 113, which opening communicates fluid from the inlet chamber 122 in the pump to the opposite side of the pumping means 112, as described above in reference to FIG. 1.

The

chambers

114, 122 are formed in the cover member 115 of the pump which also includes a port 123 communicating the inlet chamber 122 of the pump with a fluid reservoir 121. The cover member 115 of the pump is formed with an axially extending bore 132 therein which opens at its ends into the inlet chamber 122 and the reservoir 121, respectively. The bore 132 is configured as described above in reference to FIG. 1. A valve member 133 is slidably supported in the bore 132 and is operable to bypass fluid from the discharge chamber 114 to the inlet chamber 122 in response to a predetermined pressure differential thereacross, as will be described in detail below. An end 138 of the valve member 133 adjacent the inlet passageway 122 is adapted to sealingly engage a valve seat 151 which is fixed to the cover member 115 when the valve is in its position as shown in FIG. 3 so that discharge fluid in the chamber 114 is prevented from entering the inlet chamber 122. The valve seat is an annular member having a generally triangular cross section to provide a frusto-conical surface which converges in the direction of the valve bore 132. The valve member 133 moves toward the right, as viewed in the drawings, to bypass fluid from the discharge chamber to the inlet chamber between the end 138 of the valve member and the valve seat 151.

The valve member 133 includes a generally cylindrical portion 141 (see FIG. 4), having a diametrical extent substantially the same as the diametrical extent of the bore 132 and which guides the valve member as it moves in the bore 132. The cylindrical portion 141 is formed adjacent an end portion 145 which extends from the portion 141 toward the reservoir 121. The end portion 145 iof the valve member 133 is smaller in diameter than the portion 141 and provides a chamber 146 between the end portion 145 of the valve member and the bore 132. The end portion 145 includes a slightly enlarged cylindrical portion 147 having annular grooves therein and which is adjacent the reservoir 122. The portion 147 is in sealing engagement with a cylindrical opening 150 at the end of the bore 132. Spring means 152 is located in the chamber 146 and is effective to urge the valve member 133 to the left, as viewed in the drawings and into engagement with the valve seat 151.

The chamber 146 communicates with a check valve means 154 through `a passageway 153 which extends from the chamber 146 to the central portion of the valve member 133. The central portion of the valve member 133 contains the check valve means 154 seated against a reaction ball 164 to urge the check ball against a valve seat formed in the valve member 133 to close the passage 153 against fluid flow therethrough. When pressure in the chamber 146 overcomes the force of the spring 156, the check ball 155 is moved off the valve seat and fluid in the chamber 146 flows through the passage 153 past the check ball 155, reaction ball 164 and to the reservoir 121. The chamber 146 also communicates with the fluid system through a port extending between the bore 132 and the discharge passage 117 by means which will be described in detail hereinafter, so that the fluid pressure in the chamber 146 changes in response to changes in the system pressure.

The pump 100 is provided with flow restricting means for controlling the differential pressure forces acting across the valve member 133. As shown in FIG. 3, the flow restricting means includes a primary flow restricting orifice 124 in the cover member 115 between the discharge chamber 114 and the system and through which fluid flowing to the system passes. The flow restricting means additionally includes a secondary flow restriction between the primary flow restriction 124 and the chamber 146. The secondary flow restriction is provided by a helical groove 141a formed in the cylindrical portion 141 of the valve member 133 and which extends between

chambers

114, 146 past the port 160. When the check valve means 154 opens, fluid flows through the groove 14111 to the chamber 146 in a restricted manner. Restriction of the fluid flowing to the chamber 146 causes a drop in the pressure thereof so that when fluid passes through the groove 141a, the force acting on the valve member to urge it to the left, as viewed in the drawings, is reduced to increase the differential pressure across the valve member and cause the valve member to move toward the right as viewed in the drawings. The pressure drop across the secondary orifice depends on the effective length of the groove 141:1, so that the pressure in the chamber 146 varies as the valve member 133 moves in the bore 132. Moreover, when the pressure in the system increases the pressure in the chamber 146 also increases, relative to the fluid pressure acting adjacent the end 138 of the valve member, thus tending to reduce the pressure differential across the valve member and shift the valve member toward the left to increase the flow of fluid to the system. It has been found that shifting of the valve member 133 in response to increases in system pressure can be controlled by varying the internal diameter of the valve seal 151. To increase flow to the system under increasing pressure, for example, the internal Vdiameter of the seat 151 is made larger.

The iiow control means 101 additionally includes means for directing fluid bypassed from the discharge chamber 114 to the inlet chamber 122 at a high velocity to limit pressure losses which might otherwise be dissipated as heat in the fluid. The end 138 of the valve member 133 includes an arcuately curved or flared portion 139 which terminates in a frusto-conical peripheral portion 140 of the valve member. The portion 140 is adapted to sealingly engage the valve seat 151 when the valve member 133 is in its position illustrated in FIG. 3, and provides a nozzle-like opening between the discharge and inlet chambers as the valve member 133 moves to a bypass position. The

portions

139, 140 of the valve member provide an unimpeded flow path for the bypassed liuid and cooperate to direct the bypassed Huid inwardly of the valve member and then outwardly thereof into the inlet chamber 122 at a high velocity.

Moreover, the amount of Huid bypassed and, therefore, the flow droop provided by the flow control means, is determined by the angle of the frusto-conical peripheral por-tion of the valve member and the lconfiguration and diameter of the ared end portion 139.

The nozzle-like opening formed between the valve seat 151 and the end portion 139 of the valve member has an area which changes with movement of the valve. As the valve member 133 moves to the right, the nozzle formed between the valve seat 151 `and the liared end portion 139 suddenly ybecomes large due to the curvature of the end portion, Ias described, so that the pressure tending to urge the valve member to the right, as viewed in the drawings, is controlled accordingly. It should be appreciated that the length ofthe secondary orilice formed by the helical groove 141a and the area of the nozzle formed between the valve member and the valve seat 151 change simultaneously as the valve is moved in the bore 132 so lthat a controlled amount of flow droop of pumped liuid is maintained to the system when the valve member 133 is bypassing fluid.

Operation of the pump 100 should be apparent from the foregoing description. When the pump is operated at speeds 'below a predetermined speed uid in pump discharge chamber 114 acts on the frusto-conical portion of the valve member 133, tending to urge the valve member 133 to the right against the bias of the spring means 152. The pump discharge lluid flows from the discharge chamber 114 through the flow restricting orifice 124 and to the system through the passage 117. Fluid in the passage 117 is in communication with the chamber 146 through the port 160 and the helical groove 141a formed on the valve member 133 so that a pressure differential is provided across the valve member which acts in conjunction with the bias of `the spring means to maintain the valve member in a position wherein a controlled generally constant `amount of fluid flows to the system at pump speeds above the predetermined speed, the valve member moves to bypass -additional fluid from the system so that a controlled droop in flow to |the system is provided. When the pressure of the fluid in the system reaches a value suiiicient to overcome the force of the spring 156, the check valve means 154 opens to permit liuid flow from the chamber 146 tothe reservoir as described above. When the check valve means 154 opens, fluid flows through the secondary orice formed by the helical groove, 141a and into the chamber 146 in 4a restricted manner, increasing the pressure differential across the valve member 133 and resulting in movement of the valve member 133 to the right, as viewed in `the drawings, to bypass additional fluid from the system. As noted above, the pressure of the fluid flowing into the chamber 146 is determined by the effective length of the secondary orifice formed on the valve member and thus the pressure in the chamber 146 increases in response to movement of the valve member toward the left and decreases as the valve 10 member moves toward the right. The amount of movement of the valve member is controlled by the pressure differential acting thereon, as well as the force of the spring 152 and when the pressure forces and spring force are balanced, the valve ember 133 is stationary in the bore 132 at a position wherein fluid is being bypassed from the discharge chamber 114 to the inlet chamber 122.

As the valve member 133 moves to the right, as Viewed in the drawings, the arcuately ared end portion 139 of the valve is moved adjacent the valve seat 151 so that an increased amount of fluid is bypassed from the discharge chamber 114 to the inlet 122 to provide a controlled amount of ow droop in the fluid flowing to the system.

When the system pressure increases and the pump is operating at a speed above the predetermined speed, the increased system pressure is communicated to the chamber 146 and is effective to cause movement of the valve member toward the left to increase the ow of pumped fluid to the system.

From the above description, it should be lapparent that at a given system pressure the liow control means is effective to provide a generally constant flow of uid to the fluid system at pump speeds below a predetermined speed and a controlled decreasing flow of fluid to the system at pump speeds above the predetermined speed. That is to say, the flow control means is elective to provide a controlled droop in flow to the system at `a given system pressure as pump speeds increase above the predetermined speed. However, if the pressure of the liuid in the system increases when the pump speed is above the predetermined speed, the flow control means is effective to provide increased ow to the system thereby providing steering power to the power steering mechanism at high engine speeds.

FIG. 2 shows a modified pump 10 embodying the present invention and including a modified valve member 33 forming a portion of the flow control means 16'. The modied valve 33 includes a central cylindrical opening 69 extending therethrough between the inlet chamber 14a' of the pump and the reservoir 21. Additionally, the cover member 15 is modified such that a relief valve means 61 opens into the chamber 54 formed between the bore 32 and the end portion 45 of the valve member 33. Operation of the valve member 33 is essentially the same as described in reference to FIG. 3 except that when fluid is bypassed from the discharge chamber 14' to the inlet chamber 14a past the frustoconical portion 40 of the valve member, the high velocity bypass fluid directed inwardly of the valve member effects a low pressure immediately to the left of the valve member 33'. The low pressure created adjacent this end of the valve in the inlet chamber 14a is effective to provide a flow of uid from the reservoir 21 through the central passage 69 in the valve member 33 and into the inlet chamber 14a. This operation of the valve member 33 may also be termed supercharging since the pressure in the reservoir is effective to urge the fluid therein through the valve member 33 into the inlet chamber 14a.

Fluid pressure in the system is communicated to a chamber 54 between the end portion 45 and the bore 32 to open the relief valve means 61', as described above in reference to FIG. 3, so that lluid may be directed therethrough to the reservoir 21'. Fluid from the system is communicated to the relief valve 61' through a helical groove 69a on the outer periphery of the valve 33', as described in connection with FIG. 3, which controls the liuid pressure in the chamber 54.

While several embodiments of the present invention have been illustrated and described herein in considerable detail, the present invention is not to be considered limited to the precise constructions shown. It is my intention to cover hereby all adaptations, modifications, and uses of the present invention which come within the scope of the following claims.

Having described my invention, I claim:

1. A pump for supplying fluid to a fluid system comprising pumping means for pumping fluid from a fluid inlet to an outlet in communication with the system, flow control means operable to bypass fluid from the system and to reduce flow to the system as pump speed increases above a predetermined speed, said flow control means including a valve member movable in a first direction to bypass fluid and in a second direction opposite to said first direction to bypass less fluid as the pressure in the system increases whereby said pump when fluid is being bypassed provides reduced flow to the system and provides an increased flow to the system as system pressure increases, a first flow restricting means located between the pump outlet and said system and a second flow restricting means located between said chamber and said system, said second flow restricting means including a helical groove formed on said valve member and wherein movement of said valve member in said first direction is effective to increase the length of said second flow restricting means.

2. A pump for supplying fluid to a fluid system comprising pumping means for pumping fluid from a fluid inlet to an outlet in communication with the system, flow control means operable to bypass fluid from the system i and to reduce flow to the system as pump speed increases above a predetermined speed, said flow control means including a valve member movable in a first direction to bypass fluid and in a second direction opposite to said first direction to bypass less fluid as the pressure in the system increases whereby said pump when fluid is being bypassed provides reduced flow to the system and provides an increased flow to the system as system pressure increases, said valve member including a peripheral surface portion tapering inwardly in the direction of flow of the by-passed fluid so that the portion exposed to inlet pressure is of a lesser cross sectional area than the portion exposed to discharge pressure and effective to direct by-passed fluid radially inwardly of the valve member and toward the pump inlet at a substantial velocity.

3. A pump for supplying fluid to a fluid system cornprising pumping means for pumping fluid from a fluid inlet to an outlet in communication with the system, flow control means operable to bypass fluid from the system and to reduce flow to the system as pump speed increases above a predetermined speed, said fiow control means including a valve member movable in a first direction to bypass fluid and in a second direction opposite to said first direction to bypass less fluid as the pressure in the system increases whereby said pump when fluid is being bypassed provides reduced flow to the system and provides an increased flow to the system as system pressure increases, said valve member including a peripheral surface portion effective to direct bypassed fluid radially inwardly of the valve member and toward the pump inlet at a substantial velocity, and a second surface portion adjacent said peripheral surface portion, said second surface portion including an arcuately flared peripheral surface on said valve member and operable to direct bypassed fluid radially outwardly of said valve member and toward said pump inlet.

4. A pump for supplying fluid from a reservoir to a fluid system comprising means defining a pump inlet chamber in communication with said reservoir, pumping means operable to pump fluid from said reservoir through said inlet chamber to said system, flow control means operable to by pass fluid ,from the system including a valve member having a first position blocking bypassing of fluid and movable from said first position to lbypass fluid to said inlet chamber, means for directing said bypass fluid at a relatively high velocity into said inlet chamber to effect flow of fluid from said reservoir into said inlet chamber due to the velocity and direction of flow of said bypassed fluid and nozzle means defining an opening and directing said bypassed fluid through the opening to said pump inlet at a high velocity, said nozzle means including a peripheral portion of said valve member having a tapered surface engageable wit-h a valve seat, said opening varying in area as said valve member moves from said first position to change the amount of bypass fluid.

5. A pump for supplying fluid from a reservoir to a fluid system comprising means defining la pump inlet chamber' in communication with said reservoir, pumping means operable to pump fluid from said reservoir through said inlet chamber to said system, flow control means operable to bypass fluid from the system including a valve member having a first position blocking bypassing of fluid and movable from said first position to lbypass fluid to said inlet chamber, means for directing said bypass fluid at a relatively high velocity into said inlet chamber to effect flow of fluid from said reservoir into said inlet chamber due to the velocity and direction of flow of said bypassed fluid, nozzle means defining an opening and directing ysaid bypassed fluid through the opening to said pump inlet at 4a high velocity, said nozzle means including a peripheral portion of said valve member, and flow passage means communicating said inlet chamber with said reservoir and including a central opening extending through said valve member between said reservoir and said inlet chamber, whereby said nozzle means directs said bypassed fluid to provide a low `pressure region adjacent said flow passage means and effects movement of fluid from said reservoir into said inlet chamber.

6. A pump for supplying fluid from a reservoir to a fluid system comprising means defining a pump inlet chamber in communication with said reservoir, pumping means operable to pump fluid from said reservoir through said inlet chamber to said system, flow control means operable to bypass fluid from the `system including a valve member having a first position blocking bypassing of fluid and movable from said first position to bypass fluid to said inlet chamber. means for directing said bypass fluid at a relatively high velocity into said inlet chamber to effect flow lof fluid `from said reservoir into said inlet chamber due to the velocity and direction of flow of said bypassed fluid, nozzle means defining `an opening and directing said bypassed fluid through the opening to said pump inlet at a high velocity, said nozzle means including a peripheral portion of said valve member, and flow passage means communicating said inlet chamber thereof with said reservoir and including a port extending between said reservoir and said inlet chamber adjacent said nozzle means, whereby said nozzle means directs said bypassed fluid to provide a low pressure region adjacent said flow passage means and effects movement of fluid from said reservoir into said inlet chamber.

7. A pump for supplying fluid from a reservoir to a fluid system comprising means defining a pump inlet chamber in communication with said reservoir, pumping means operable to pump fluid from said reservoir through said inlet chamber to said system, flow control means operable to bypass fluid from the system including a valve member having a first position blocking bypassing of fluid and movable from said first position to bypass fluid to said inlet chamber, means for directing said bypass fluid at a relatively high velocity into said inlet chamber to effect flow of fluid from said reservoir into said inlet chamber due to the velocity and direction of flow of said bypassed fluid, flow restricting means effective to produce a drop in pressure of said fluid flowing from the discharge of said pumping means, said flow restricting means including a primary flow restriction between said discharge chamber and said system and effective to provide a pressure drop therebetween, and a secondary flow restriction between said primary flow restriction and a portion of said valve member, said secondary flow restriction effective lo produce a pressure differential across said valve member and wherein said secondary flow re- 13 striction variably restricts the flow of uid therethrough in response t-o movement of said valve member.

8. A fluid pump for supplying fluid `to an external fluid system and compri-sing, pumping means having inlet and discharge chambers, flow control means for controlling the ow of fluid from said discharge chamber to said system, said liow `control means including a valve member movable in response to a predetermined uid pressure differential acting thereacross to bypass fluid from said discharge chamber to said inlet chamber and flow restriction means operable to control the pressure differential acting on said valve member, said iiow restriction means including a flow restriction between said system and a part of said valve member remote from said discharge chamber, said flow restriction including a helical groove formed on a periphery of said valve member and being operable to variably restrict the flow of fluid :therethrough in response to movement of said valve member to Vary the pressure differential acting on said valve member, and relief valve means communicating with said flow restriction and effective at a predetermined system pressure to permit fluid flow through said liow restriction and to a reservoir of said system.

9. A fluid pump for supplying uid to an external liuid system comprising pumping means having inlet and discharge chambers, said inlet chamber communicating with said pumping means and operable to direct inlet uid thereto from a reservoir of said system and said discharge chamber communicating discharge fluid from said pumping means with said system, flow control means communicating with said discharge chamber and operable to bypass fluid from said discharge chamber to said inlet chamber, said flow control means including a valve member movable from a first position wherein the uid in said discharge chamber flows to said system to a bypass position wherein a portion of said fluid in said discharge chamber is directed into :said inlet chamber at a relatively high velocity to provide a -low pressure region in said inlet chamber, port means communicating said inlet chamber with said reservoir including an opening in said inlet chamber adjacent said low pressure region, with said high velocity bypass uid effecting movement of said fluid from said reservoir into said inlet chamber through said port means, a first ow restriction between said discharge chamber and said system, and a second flow re- :striction between said system and a portion of said valve member remote from said discharge chamber, said second flow restriction including a helical groove formed on a periphery of said valve member and effective to communicate pressure of said system to said portion of said valve member for urging said Valve member toward its said first position.

10. A pump as defined in claim 2 wherein said frustoconical periphery of said valve member is engageable with a valve seat member in its position wherein fluid is not bypassed, said valve member and said valve seat cooperating to provide a variable area opening through which said bypass fluid flows and wherein the area of said opening increases as said valve member moves in said first direction.

11. A pump as defined in claim 4 further including fiow passage means communicating said inlet chamber thereof with said reservoir and wherein said nozzle means directs said bypassed fiuid to provide a low pressure region adjacent said ow passage means and effects an increased movement of liuid from said reservoir into said inlet chamber.

12. A pump as defined in claim 6 and further including a ledge formed in said inlet chamber intermediate said nozzle means and said port.

13. A pump as defined in claim 4 wherein said nozzle means further includes an arcuately flared end portion of said valve member adjacent said frusto-conical surface.

14. A pump as defined in claim 7 wherein said secondary liow restriction is formed by a helical groove on a periphery of said valve member.

15. A fluid pump for supplying fluid to an external fluid system comprising pumping means having inlet and discharge chambers, said inlet chamber communicating with said pumping means and operable to direct inlet fluid thereto from a reservoir of said system and said discharge chamber communicating discharge fluid from said pumping means with said system, ow control means communicating with said discharge chamber and operable -to bypass fluid from said discharge chamber to said inlet chamber, said flow control means including a valve member movable from a first position wherein the fluid in said discharge chamber flows to said system to a bypass position wherein a portion of said fluid in said discharge chamber is directed into said inlet chamber at a relatively high velocity to provide a low pressure region in said inlet chamber, and port means communicating said inlet chamber with said reservoir including an opening in said inlet chamber adjacent said low pressure region, with said high velocity bypass fluid effecting an increased movement of said fluid from said reservoir into said inlet chamber through said port means, said port means including a first opening extending axially through said valve member and opening at one end thereof into said inlet passageway and at the other end thereof into Isaid reservoir, and a second opening directly communicating said inlet passageway with said reservoir, said second opening being remote from said first opening.

16. A pump as defined in claim 15 and wherein said valve member includes a peripheral portion operable to direct liuid inwardly of said valve member from said discharge chamber to said inlet chamber at said relatively high velocity and effective to create said low pressure region adjacent said one end of said opening in said valve member.

17. A pump as defined in claim 16 and further including chamber means surrounding a portion of said valve member and communicating with said system, and relief valve means between said chamber means and said reservoir for communicating said chamber means with said reservoir at system pressures above a predetermined pressure.

References Cited UNITED STATES PATENTS 3,009,420 11/ 1961 Livermore et al. 10S-42X 3,103,891 9/1963 Fulton et al. 103-42 3,110,266 11/1963 Livermore 103-42 X 3,146,720 9/1964 Henry 103-41 X 3,167,020 1/1965 Rohde 103--41 X 3,349,714 10/1967 Grenier 103-41 3,253,607 5/ 1966 Drutchas 103-42 X DONLEY I. STOCKING, Primary Examiner.

W. I. KRAUSS, Assistant Examiner.

U.S. Cl. X.R. 103-42