CA1134202A - Hydraulic pump - Google Patents
Hydraulic pumpInfo
- Publication number
- CA1134202A CA1134202A CA322,660A CA322660A CA1134202A CA 1134202 A CA1134202 A CA 1134202A CA 322660 A CA322660 A CA 322660A CA 1134202 A CA1134202 A CA 1134202A
- Authority
- CA
- Canada
- Prior art keywords
- pump
- cam ring
- side plate
- pump housing
- drive shaft
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
- F04C14/24—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves
- F04C14/26—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves using bypass channels
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Details And Applications Of Rotary Liquid Pumps (AREA)
- Rotary Pumps (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A vane type hydraulic pump comprising a pump housing receiving therein a non-rotatable cam ring and first and second non-rotatable but axially slidable side plates. A
pump rotor rotatable integrally with a drive shaft is receiv-ed in an internal cam bore of the cam ring and, when rotated, sends out pressurized fluid to a discharge port as well as to a pressure acting chamber defined between said pump housing and said second side plate, which thus presses the first side plate on one side surface of the cam ring. The first and se-cond side plates define at a contact portion therebetween a bypass cavity, which is fluidically communicated with a flow volume control value for returning bypassed fluid from the flow volume control valve into the cam ring therethrough.
A vane type hydraulic pump comprising a pump housing receiving therein a non-rotatable cam ring and first and second non-rotatable but axially slidable side plates. A
pump rotor rotatable integrally with a drive shaft is receiv-ed in an internal cam bore of the cam ring and, when rotated, sends out pressurized fluid to a discharge port as well as to a pressure acting chamber defined between said pump housing and said second side plate, which thus presses the first side plate on one side surface of the cam ring. The first and se-cond side plates define at a contact portion therebetween a bypass cavity, which is fluidically communicated with a flow volume control value for returning bypassed fluid from the flow volume control valve into the cam ring therethrough.
Description
~i~34Z~2 The present inv~ntion relates to a hydraulic pump sui-t-able for use with an automative power steering apparatus.
In hydraullc pumps used for automotlve power steerlng apparatus, a pump rotor ls rotatlonally driven by an automo-tive engine, and the flow volume discharged from a pump is in-creased as the rotational speed of the engine is raised. For this reason, it is a practice to reduce engine power loss by providing the hydraulic pump with a flow control valve for by-passing to a low pressure zone fluld in excess ofthat required by the power steering apparatus.
In a known hydraulic pump of the above type a pressure plate is provided at one side of a cam ring which defines the pump chamber. Inlet and outlet ports are formed ln the pressure plate to open respectively to pump chamber inlet and outlet areas. A bypass passage is formed in a pump body and has a bypass hole whose extent of opening is controllable by a flow control valve. The bypass passage connected with an inlet passage which fluidically connects the pump inlet port with a reservoir. Thus the flow from the reservoir joins the bypassed flow at the inlet passage so as to be conducted to the inlet port. However, such provision of the bypass passage in the pump body results in difficultyin machining, and in lowering the suction efficiency of the pump.
Accordingly, it is a primary object of the present inven-tion to provide a hydraulic pump in which the above disadvant-ages are obviated or mitigated.
According to the present invention there is provided a hydraulic pump comprising a pump housing having an inlet port and a discharge port; a cam ring received in the pump housing and having an internal cam bore; a drive shaft rotatably carried ~ .
~34;~2 by the pump housing and extending into the internal cam bore in co-axial alignment with the axis of the internal cam bore; a pump rotor carried on the drive shaft for integral rotation therewith and received in the internal cam bore for effecting pump action in cooperation therewith when rotated by the drive shaft; first and second side plates received in the pump hous-ing so as to be slidable in an axial direction of the drive shaft and held in contact engagement with each other for defin-ing a bypass cavity there~etween, at least two of the pump hous-ing, the cam ring and the first side plate defining therebetweenan inlet area fluidically communicated with the inlet port and the bypass cavity for conducting fluid into the internal cam boreand an outlet area fluidically communicated with the dis-charge port for receiving and delivering pressurized fluid from the internal cam bore into the discharge port, the second side plate defining between itself and the pump housing a pressure acting chamber fluidically communicated with the outlet area for pressing the first side plate upon one side surface of the cam ring through the second side plate; and a flow control valve fluidically communicated with the discharge port for returning into the bypass cavity a part of pressurized fluid delivered to the discharge port.
According to a further aspect of the invention there is provided a pump comprising a housing having a pumping cavity defined by a circumferentially extending wall, a first radially extending end wall fixed to the circumferentially ex-tending wall and a second radially extending end wall axially moveable relative to the circumferentially extending wall, an fluid inlet for connecting a reservoir to the pumping cavity and a fluid outlet to discharge fluid from the pumping cavity, ~3~
a pumping element disposed in the pumping cavity to pump fluid from the inlet to the outlet and a pressure receiving chamber connected to the outlet and operable to bias the second radi-ally extending end wall toward the first radially extending end wall upon delivery of fluid to the chamber.
In a preferred embodiment of the present invention first and second side plates are provided which are received in the pump housing so as to be slidable in an axial direction of the drive shaft and are held in contact engagement with each other for defining the bypass cavity therebetween. The second side plate defines between itself and the pump housing a pres-sure acting chamber, into which pressurized fluid is delivered for pressing the first side plate upon one side surface of the cam ring through the second side plate. Further, at least two of the pump housing, the cam ring and the first side plate de-fine therebetween an inlet area fluidically communicated with the inlet port and the bypass cavity for conducting fluid into the internal cam bore and an outlet area fluidically communicat-ed with the discharge port for receiving and delivering pres-surized fluid from th~ internal cam bore into the dischargeport.
In the hydraulic pump of the preferred embodiment a part of pressurized fluid bypassed by the flow control valve is re-turned via the bypass cavity directly to the inlet area where the bypassed part of pressurized fluid joins non-pressurized fluid from the inlet port, so that the suction efficiency of the pump can advantageously be improved. In addition, the form-ing or machining of the bypass cavity is easy sinc~ the same is provided at the contact portion between the first and second side plates.
~3~ 2 An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which:-, FIGURE 1 is~a longitudinal sectional view of a hydraulicpump;
FIGURE 2 is a sectional view of the device, taken along the line II-II of FIGURE l;
FIGURE 3 is a sectional view of the device, taken along the line III-II~ of FIGURE l; and FIGURE 4 (which is on the same sheet of drawings as FIGURE 1) is a fragmental sectional view of the device, taken along the line IV-IV of FIGURE 1.
Referring now to the drawings and particularly, to FIGURES
1 and 2 thereof a pump body 10 has a support member 11 inserted into one open end of the pump body so as to constitute a pump housing. A rotor drive shaft 12, driven by an automotive engine, not shown, is rotatably carried b~r the support member 11 through a bearing 13. One end of the drive shaft 12 extends into a by-pass hole 14 of a cylindrical sleeve portion 10a, which is form-ed in the pump body 10 in axial alignment with the axis of thedrive shaft 12. The pump body 10 has slidably inserted therein-to two side plates, that is, a pressure plate 15 and a subplate 16 through which the drive sha~t 12 extends. Each of the side plates has an aperture 15a, 16a respectively formed therein.
The pressure plate 15 rotatably carries within the aperture 15a one end of the drive shaft 12. The aperture 16a in subplate 16 snugly fits on the cylindrical sleeve portion 10a of the pump body, the bypass hole 14 being formed in the sleeve portion 10a.
A cam ring 17 is interposed between the pressure plate 15 and one side wall lla of the support member 11 and is positioned by .
~3~Z~
means of a plurality of pins 18, which extend through the two plates 15 and 16, the cam ring 17 and the support member 11.
The cam ring 17 is formed with an internal cam surface 17a as illustrated in FIGURE 3. Within a space defined by the cam surface 17a, the support member side wall lla and the pres-sure plate 15 there is rotatably contained a pump rotor 20, which is carried on the drive shaft 12 and non-rotatably attach-ed thereto through a spline connection. The pump rotor 20, to-gether wi-th the cam ring 17, define two crescent-shaped pump chambers 21 with an angular separation of 180~degrees. The pump rotor 20 is formed on its circumferential surface with a plura-lity of radial slots 20a. Vanes 22 are slidably received in slots 20a and contact the cam surface 17a of the cam ring 17.
These vanes 22 separate each of the pump chambers 21 into a plurality of sealed chambers.
The support member side wall lla and the pressure plate 15 are formed respectively with inlet ports 23 and 24 opening respectively to inlet areas of the pump chambers 21. Outlet ports 25 and 26 are also formed in the side wall lla and pressure plate 15 and open respectively to outlet areas of the pump chambers 21. The inlet ports 23, 24 and the outle-t ports 25, 26 are alternately disposed with an angular distance of approxi-mate 90-degrees, as shown in FIGURE 3. The inlet ports 23, 24 are in fluid communication with an annular groove 27 formed in the pump body 10. The annular groove 27 is, in turn, in fluid communication through an intake hole 29 with a reservoir 28, which is mounted on the pump ~ody 10 by the use of a bracket 19.
Thus, oil contained in the reservoir 2~ is conducted from the intake hole 29 to each inlet area of the pump chambers 21 through the annular groove 27 and the inlet ports 23, 24. Further, the in-- 5 ~
~3~Z'~
let ports 24 formed on the pressuxe plate 15 are fluidically communicated with the bypass hole 14 through a bypass cavity 30, which extends in a diametrical direction across the inter-face between the pressure plate 15 and the subplate 1~, as shown in FI~URE 4.
The outlet ports 26 formed on the pressure plate 15 are ~luidically communicated with outlet recesses 31, which extend through the subplate 16. The outlet recesses 31 open into a pressure actin~ chamber 32 defined between the subplate 32 and lG the pump body 10. Further, the outlet ports 26 are connected through communication passages47 with a balancing groove 33 formed on a side surface of the pressure plate 15 and the balan-cing groove 33 is, in turn, communicated with all of the radial slots 20a. The side wall lla of the support member 11 is form-ed with a balancing groove 34 in a face to face relation with the balancing groove 33. The balancing groove 34 is, in turn, connected with all o the radial slots 20a. A tapped hole 10b is formed on the pump body 10 to facilitate pump mounting.
A flow control valve 35 is provided for controlling the pump discharged flo~ rate. The pump body 10 is formed with a valve hole 36 intersecting with the bypass hole 14. The valve hole 36 has slidably fitted therein a valve spool 37 for con-trolling the extent of opening of the bypass hole 14. One end of the valve hole 36 is connected with the pressure acting cham-ber 32 through a hole 38 and also with a discharge port 40 through a throttle element or orifice 39. The other end of the valve hole 36 is communicated with the downstream side of the orifice 39 through passages 41, 42 and 43. A spring 44 within the bore 36 presses the valve spool 37 toward the one end of the valve hole 36. Therefore, the rate of working oil discharg-~L3~2~2 ed from the discharg~ port 40 through the orifice 39 determines a pressure drop across the orifice. The valve spool 37 maintains this constant by controlling the extent of opening of the by-pass hole 14. In this way a constant flow rate is supplied to a power steering apparatus not shown. A numeral 45 denotes a pressure relief valve provided in the valve spool 37.
The operation of the pump as constructed above will be described hereinunder. When the pump rotor 20 is drivingly rotated together with the drive shaft 12 by an automotive en-gine, working oil is sucked from the reservoir 28 into theinlet areas of the pump chambers 21 t~rough the intake hole 29, the annular groove 27, and thP inlet ports 23, 24. The working oil pressurized at the ou~let areas of the pump chambers 21 is conducted to the discharge port 40 through the outlet ports 26, the outlet recesses 31, the pressure acting chamber 32, the hole 38, the one end of the valve hole 36 and the orifice 39 and is discharged from the discharge port 40 so as to be supplied to the power steering apparatus. A part of the working oil deliver-ed to the outlet port 26 is conducted to the radial slots 20a and the balancing groove 34 through the communication passages 47 and the balancing groove 33, so that the vanes 22 are press-ed upon the cam surface 17a of the cam ring 17, with the pump rotor 20 balancing in the thrust direction. Further, the pres-surized working oil within the pressure acting chamber 32 causes through the subplate 16 the pressure plate 15 to be pressed upon the cam ring 17.
The flow rate of the working oil delivered from the out-let areas of the pump chambers 21 is in proportion to the rota-tional speed of the pump rotor 20, namely to the engine rotation-al speed. When the flow rate is increased with an increase of - 7 ~
~39~2f~
the engine rotational speed, then the pressure drop across the orifice 39 rises. The valve spool 37 slides against the force of the spring 44 so as to increase the opening of the bypass hol~ 14. A part of the working oil flowing into the one end of the valve hole 26 i5 thus bypassed into the bypass hole 14, and the bypassed flow is conducted to the inlet ports 24 through the bypass cavity 30 formed between the pressure plate 15 and the subplate 16, thus being returned directly to the inlet areas of the pump chambers 21. Such control by the valve spool 37 of the bypass flow permits the difference between pressures before and behind the orifice 39 to be maintained constant, whereby the working oil is always discharged from the discharge port at a constant flow rate.
~20 : ,. ' . : ,.
In hydraullc pumps used for automotlve power steerlng apparatus, a pump rotor ls rotatlonally driven by an automo-tive engine, and the flow volume discharged from a pump is in-creased as the rotational speed of the engine is raised. For this reason, it is a practice to reduce engine power loss by providing the hydraulic pump with a flow control valve for by-passing to a low pressure zone fluld in excess ofthat required by the power steering apparatus.
In a known hydraulic pump of the above type a pressure plate is provided at one side of a cam ring which defines the pump chamber. Inlet and outlet ports are formed ln the pressure plate to open respectively to pump chamber inlet and outlet areas. A bypass passage is formed in a pump body and has a bypass hole whose extent of opening is controllable by a flow control valve. The bypass passage connected with an inlet passage which fluidically connects the pump inlet port with a reservoir. Thus the flow from the reservoir joins the bypassed flow at the inlet passage so as to be conducted to the inlet port. However, such provision of the bypass passage in the pump body results in difficultyin machining, and in lowering the suction efficiency of the pump.
Accordingly, it is a primary object of the present inven-tion to provide a hydraulic pump in which the above disadvant-ages are obviated or mitigated.
According to the present invention there is provided a hydraulic pump comprising a pump housing having an inlet port and a discharge port; a cam ring received in the pump housing and having an internal cam bore; a drive shaft rotatably carried ~ .
~34;~2 by the pump housing and extending into the internal cam bore in co-axial alignment with the axis of the internal cam bore; a pump rotor carried on the drive shaft for integral rotation therewith and received in the internal cam bore for effecting pump action in cooperation therewith when rotated by the drive shaft; first and second side plates received in the pump hous-ing so as to be slidable in an axial direction of the drive shaft and held in contact engagement with each other for defin-ing a bypass cavity there~etween, at least two of the pump hous-ing, the cam ring and the first side plate defining therebetweenan inlet area fluidically communicated with the inlet port and the bypass cavity for conducting fluid into the internal cam boreand an outlet area fluidically communicated with the dis-charge port for receiving and delivering pressurized fluid from the internal cam bore into the discharge port, the second side plate defining between itself and the pump housing a pressure acting chamber fluidically communicated with the outlet area for pressing the first side plate upon one side surface of the cam ring through the second side plate; and a flow control valve fluidically communicated with the discharge port for returning into the bypass cavity a part of pressurized fluid delivered to the discharge port.
According to a further aspect of the invention there is provided a pump comprising a housing having a pumping cavity defined by a circumferentially extending wall, a first radially extending end wall fixed to the circumferentially ex-tending wall and a second radially extending end wall axially moveable relative to the circumferentially extending wall, an fluid inlet for connecting a reservoir to the pumping cavity and a fluid outlet to discharge fluid from the pumping cavity, ~3~
a pumping element disposed in the pumping cavity to pump fluid from the inlet to the outlet and a pressure receiving chamber connected to the outlet and operable to bias the second radi-ally extending end wall toward the first radially extending end wall upon delivery of fluid to the chamber.
In a preferred embodiment of the present invention first and second side plates are provided which are received in the pump housing so as to be slidable in an axial direction of the drive shaft and are held in contact engagement with each other for defining the bypass cavity therebetween. The second side plate defines between itself and the pump housing a pres-sure acting chamber, into which pressurized fluid is delivered for pressing the first side plate upon one side surface of the cam ring through the second side plate. Further, at least two of the pump housing, the cam ring and the first side plate de-fine therebetween an inlet area fluidically communicated with the inlet port and the bypass cavity for conducting fluid into the internal cam bore and an outlet area fluidically communicat-ed with the discharge port for receiving and delivering pres-surized fluid from th~ internal cam bore into the dischargeport.
In the hydraulic pump of the preferred embodiment a part of pressurized fluid bypassed by the flow control valve is re-turned via the bypass cavity directly to the inlet area where the bypassed part of pressurized fluid joins non-pressurized fluid from the inlet port, so that the suction efficiency of the pump can advantageously be improved. In addition, the form-ing or machining of the bypass cavity is easy sinc~ the same is provided at the contact portion between the first and second side plates.
~3~ 2 An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which:-, FIGURE 1 is~a longitudinal sectional view of a hydraulicpump;
FIGURE 2 is a sectional view of the device, taken along the line II-II of FIGURE l;
FIGURE 3 is a sectional view of the device, taken along the line III-II~ of FIGURE l; and FIGURE 4 (which is on the same sheet of drawings as FIGURE 1) is a fragmental sectional view of the device, taken along the line IV-IV of FIGURE 1.
Referring now to the drawings and particularly, to FIGURES
1 and 2 thereof a pump body 10 has a support member 11 inserted into one open end of the pump body so as to constitute a pump housing. A rotor drive shaft 12, driven by an automotive engine, not shown, is rotatably carried b~r the support member 11 through a bearing 13. One end of the drive shaft 12 extends into a by-pass hole 14 of a cylindrical sleeve portion 10a, which is form-ed in the pump body 10 in axial alignment with the axis of thedrive shaft 12. The pump body 10 has slidably inserted therein-to two side plates, that is, a pressure plate 15 and a subplate 16 through which the drive sha~t 12 extends. Each of the side plates has an aperture 15a, 16a respectively formed therein.
The pressure plate 15 rotatably carries within the aperture 15a one end of the drive shaft 12. The aperture 16a in subplate 16 snugly fits on the cylindrical sleeve portion 10a of the pump body, the bypass hole 14 being formed in the sleeve portion 10a.
A cam ring 17 is interposed between the pressure plate 15 and one side wall lla of the support member 11 and is positioned by .
~3~Z~
means of a plurality of pins 18, which extend through the two plates 15 and 16, the cam ring 17 and the support member 11.
The cam ring 17 is formed with an internal cam surface 17a as illustrated in FIGURE 3. Within a space defined by the cam surface 17a, the support member side wall lla and the pres-sure plate 15 there is rotatably contained a pump rotor 20, which is carried on the drive shaft 12 and non-rotatably attach-ed thereto through a spline connection. The pump rotor 20, to-gether wi-th the cam ring 17, define two crescent-shaped pump chambers 21 with an angular separation of 180~degrees. The pump rotor 20 is formed on its circumferential surface with a plura-lity of radial slots 20a. Vanes 22 are slidably received in slots 20a and contact the cam surface 17a of the cam ring 17.
These vanes 22 separate each of the pump chambers 21 into a plurality of sealed chambers.
The support member side wall lla and the pressure plate 15 are formed respectively with inlet ports 23 and 24 opening respectively to inlet areas of the pump chambers 21. Outlet ports 25 and 26 are also formed in the side wall lla and pressure plate 15 and open respectively to outlet areas of the pump chambers 21. The inlet ports 23, 24 and the outle-t ports 25, 26 are alternately disposed with an angular distance of approxi-mate 90-degrees, as shown in FIGURE 3. The inlet ports 23, 24 are in fluid communication with an annular groove 27 formed in the pump body 10. The annular groove 27 is, in turn, in fluid communication through an intake hole 29 with a reservoir 28, which is mounted on the pump ~ody 10 by the use of a bracket 19.
Thus, oil contained in the reservoir 2~ is conducted from the intake hole 29 to each inlet area of the pump chambers 21 through the annular groove 27 and the inlet ports 23, 24. Further, the in-- 5 ~
~3~Z'~
let ports 24 formed on the pressuxe plate 15 are fluidically communicated with the bypass hole 14 through a bypass cavity 30, which extends in a diametrical direction across the inter-face between the pressure plate 15 and the subplate 1~, as shown in FI~URE 4.
The outlet ports 26 formed on the pressure plate 15 are ~luidically communicated with outlet recesses 31, which extend through the subplate 16. The outlet recesses 31 open into a pressure actin~ chamber 32 defined between the subplate 32 and lG the pump body 10. Further, the outlet ports 26 are connected through communication passages47 with a balancing groove 33 formed on a side surface of the pressure plate 15 and the balan-cing groove 33 is, in turn, communicated with all of the radial slots 20a. The side wall lla of the support member 11 is form-ed with a balancing groove 34 in a face to face relation with the balancing groove 33. The balancing groove 34 is, in turn, connected with all o the radial slots 20a. A tapped hole 10b is formed on the pump body 10 to facilitate pump mounting.
A flow control valve 35 is provided for controlling the pump discharged flo~ rate. The pump body 10 is formed with a valve hole 36 intersecting with the bypass hole 14. The valve hole 36 has slidably fitted therein a valve spool 37 for con-trolling the extent of opening of the bypass hole 14. One end of the valve hole 36 is connected with the pressure acting cham-ber 32 through a hole 38 and also with a discharge port 40 through a throttle element or orifice 39. The other end of the valve hole 36 is communicated with the downstream side of the orifice 39 through passages 41, 42 and 43. A spring 44 within the bore 36 presses the valve spool 37 toward the one end of the valve hole 36. Therefore, the rate of working oil discharg-~L3~2~2 ed from the discharg~ port 40 through the orifice 39 determines a pressure drop across the orifice. The valve spool 37 maintains this constant by controlling the extent of opening of the by-pass hole 14. In this way a constant flow rate is supplied to a power steering apparatus not shown. A numeral 45 denotes a pressure relief valve provided in the valve spool 37.
The operation of the pump as constructed above will be described hereinunder. When the pump rotor 20 is drivingly rotated together with the drive shaft 12 by an automotive en-gine, working oil is sucked from the reservoir 28 into theinlet areas of the pump chambers 21 t~rough the intake hole 29, the annular groove 27, and thP inlet ports 23, 24. The working oil pressurized at the ou~let areas of the pump chambers 21 is conducted to the discharge port 40 through the outlet ports 26, the outlet recesses 31, the pressure acting chamber 32, the hole 38, the one end of the valve hole 36 and the orifice 39 and is discharged from the discharge port 40 so as to be supplied to the power steering apparatus. A part of the working oil deliver-ed to the outlet port 26 is conducted to the radial slots 20a and the balancing groove 34 through the communication passages 47 and the balancing groove 33, so that the vanes 22 are press-ed upon the cam surface 17a of the cam ring 17, with the pump rotor 20 balancing in the thrust direction. Further, the pres-surized working oil within the pressure acting chamber 32 causes through the subplate 16 the pressure plate 15 to be pressed upon the cam ring 17.
The flow rate of the working oil delivered from the out-let areas of the pump chambers 21 is in proportion to the rota-tional speed of the pump rotor 20, namely to the engine rotation-al speed. When the flow rate is increased with an increase of - 7 ~
~39~2f~
the engine rotational speed, then the pressure drop across the orifice 39 rises. The valve spool 37 slides against the force of the spring 44 so as to increase the opening of the bypass hol~ 14. A part of the working oil flowing into the one end of the valve hole 26 i5 thus bypassed into the bypass hole 14, and the bypassed flow is conducted to the inlet ports 24 through the bypass cavity 30 formed between the pressure plate 15 and the subplate 16, thus being returned directly to the inlet areas of the pump chambers 21. Such control by the valve spool 37 of the bypass flow permits the difference between pressures before and behind the orifice 39 to be maintained constant, whereby the working oil is always discharged from the discharge port at a constant flow rate.
~20 : ,. ' . : ,.
Claims (2)
1. A hydraulic pump comprising:
a pump housing having an intake hole and a discharge port;
a cam ring received in said pump housing and having an internal cam bore;
a drive shaft rotatably carried by said pump housing and extending into said internal cam bore in co-axial align-ment with the axis of said internal cam bore;
a pump rotor carried on said drive shaft for integral rotation therewith and received within said internal cam bore for defining a pump chamber;
first and second side plates received in said pump housing so as to be slidable in an axial direction of said drive shaft and held in engagement with each other so as to define a bypass passage lying entirely therebetween, said cam ring and said first side plate defining therebetween inlet port means in fluidic communication with said intake hole and said bypass passage for conducting fluid into said pump chamber;
outlet port means in fluidic communication with said discharge port for receiving and delivering pressurized fluid from said pump chamber into said discharge port, said second side plate defining between itself and said pump housing a pressure acting chamber fluidically communicated with said outlet port means for pressing said first side plate against one side surface of said cam ring through said second side plate;
a throttle element in communication with said discharge port through which pressurized fluid from said out-let port means is discharged;
a flow volume control valve responsive to the pressure difference across said throttle element for returning a part of pressurized fluid through a bypass hole formed in coaxial relationship with said drive shaft; and said bypass passage extending through said first side plate for directly communicating said bypass hole with said inlet port means so as to return the part of pressurized fluid directly into said pump chamber.
a pump housing having an intake hole and a discharge port;
a cam ring received in said pump housing and having an internal cam bore;
a drive shaft rotatably carried by said pump housing and extending into said internal cam bore in co-axial align-ment with the axis of said internal cam bore;
a pump rotor carried on said drive shaft for integral rotation therewith and received within said internal cam bore for defining a pump chamber;
first and second side plates received in said pump housing so as to be slidable in an axial direction of said drive shaft and held in engagement with each other so as to define a bypass passage lying entirely therebetween, said cam ring and said first side plate defining therebetween inlet port means in fluidic communication with said intake hole and said bypass passage for conducting fluid into said pump chamber;
outlet port means in fluidic communication with said discharge port for receiving and delivering pressurized fluid from said pump chamber into said discharge port, said second side plate defining between itself and said pump housing a pressure acting chamber fluidically communicated with said outlet port means for pressing said first side plate against one side surface of said cam ring through said second side plate;
a throttle element in communication with said discharge port through which pressurized fluid from said out-let port means is discharged;
a flow volume control valve responsive to the pressure difference across said throttle element for returning a part of pressurized fluid through a bypass hole formed in coaxial relationship with said drive shaft; and said bypass passage extending through said first side plate for directly communicating said bypass hole with said inlet port means so as to return the part of pressurized fluid directly into said pump chamber.
2. A hydraulic pump as claimed in Claim 1, said inlet port means comprising first and second inlet ports opposed diametrically with respect to said cam ring and wherein said bypass passage is divided into first and second branches in a diametrical direction, respectively reaching said first and second inlet ports.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2430078A JPS54116708A (en) | 1978-03-02 | 1978-03-02 | Oil pressure pump |
| JP24300/1978 | 1978-03-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1134202A true CA1134202A (en) | 1982-10-26 |
Family
ID=12134309
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA322,660A Expired CA1134202A (en) | 1978-03-02 | 1979-03-02 | Hydraulic pump |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS54116708A (en) |
| CA (1) | CA1134202A (en) |
| DE (1) | DE2907979C2 (en) |
| FR (1) | FR2418879A1 (en) |
| GB (1) | GB2015648B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0088811B1 (en) * | 1982-03-13 | 1985-07-31 | Vickers Systems GmbH | Sliding vane pump, particularly for power steering |
| JPS60203579A (en) * | 1984-03-29 | 1985-10-15 | Honda Motor Co Ltd | Power steering system for car |
| CS260235B1 (en) * | 1986-10-21 | 1988-12-15 | Jiri Rybnicek | Positive-displacement sliding-vane pump |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3125028A (en) * | 1964-03-17 | rohde | ||
| US2827854A (en) * | 1953-03-16 | 1958-03-25 | New York Air Brake Co | Variable speed pump with non-graduating by-pass valve control |
| US2782718A (en) * | 1955-05-04 | 1957-02-26 | Vickers Inc | Speed-compensated flow control |
| USRE27241E (en) * | 1970-02-24 | 1971-12-14 | Porting for balanced hydraulic roller pump | |
| US3671143A (en) * | 1970-11-05 | 1972-06-20 | Trw Inc | Flat side valve for pressure balanced power steering pump with improved aspirator action |
| US3738784A (en) * | 1970-12-17 | 1973-06-12 | Trw Inc | Pump housing for use with top mounted or remote mounted reservoirs |
| US3806273A (en) * | 1971-10-06 | 1974-04-23 | Trw Inc | Pump with means for supercharging the pump inlet |
-
1978
- 1978-03-02 JP JP2430078A patent/JPS54116708A/en active Pending
-
1979
- 1979-02-28 FR FR7905236A patent/FR2418879A1/en active Granted
- 1979-03-01 DE DE19792907979 patent/DE2907979C2/en not_active Expired
- 1979-03-01 GB GB7907193A patent/GB2015648B/en not_active Expired
- 1979-03-02 CA CA322,660A patent/CA1134202A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2418879B1 (en) | 1982-06-04 |
| GB2015648B (en) | 1982-04-28 |
| DE2907979C2 (en) | 1985-05-30 |
| GB2015648A (en) | 1979-09-12 |
| FR2418879A1 (en) | 1979-09-28 |
| DE2907979A1 (en) | 1979-09-06 |
| JPS54116708A (en) | 1979-09-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |