JP4067348B2 - Variable displacement pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable displacement pump used in a power steering device of an automobile.
[0002]
[Prior art]
Conventionally, a variable displacement pump for assisting a steering force in a hydraulic power steering device of an automobile has been used. This variable displacement pump increases the discharge flow rate so that a large steering assist force can be obtained when the vehicle with a low rotation speed is stopped or travels at a low speed, and the discharge flow rate decreases so that the steering assist force is decreased at a high speed rotation with a high rotation speed. Is controlled to be equal to or less than a certain amount, and the steering assist force required for the power steering device can be generated.
[0003]
A conventional variable displacement pump is fixed to a pump shaft inserted into a pump body and is rotationally driven, and a rotor that houses a plurality of vanes in a holding groove so as to be movable in a radial direction, and a fitting in a pump body. A cam ring that is supported by the mounting hole so as to be movable and displaceable, and that forms a pump chamber between the outer periphery of the rotor and a side wall portion on both sides sandwiching the rotor and cam ring of the pump body, and opens to the suction side region of the pump chamber The suction side opening and the discharge side opening that opens in the discharge side region, the rotor is driven to rotate by the pump shaft, the tip of the vane is slidably contacted with the inner periphery of the cam ring, and the pump chamber is sucked from the suction side opening The working fluid is discharged from the discharge side opening.
[0004]
In the conventional variable displacement pump, the vane jumps out of the holding groove of the rotor in the radial direction along with the rotation of the rotor, slidably contacts the inner periphery of the cam ring, and performs the above-described pump operation.
[0005]
[Problems to be solved by the invention]
In the prior art, in order to cause the vane held in the holding groove of the rotor to jump out in the radial direction, the side wall of the pump body has a portion along the rotation trajectory of the base end portion of the holding groove holding the rotor vane. A suction side back pressure groove corresponding to the suction side region of the pump chamber and a discharge side back pressure groove corresponding to the discharge side region are provided. Then, the discharge fluid from the discharge side opening is introduced into the suction side back pressure groove, and the discharge fluid via the suction side back pressure groove is introduced into the discharge side back pressure groove. Thus, the vane is ejected in the radial direction by the centrifugal force accompanying the rotation of the rotor and the fluid pressure introduced into the suction-side back pressure groove and the discharge-side back pressure groove, and is pressed against the inner periphery of the cam ring.
[0006]
However, the prior art has the following problems.
(1) The discharge-side fluid introduced into the discharge-side back pressure groove is low pressure because it is passed through the suction-side back pressure groove. For this reason, in the discharge side area of the pump chamber, there is a shortage of vane removal, the vane is unstablely displaced with respect to the holding groove, and the tip of the vane contacts and separates from the inner periphery of the cam ring. The discharge efficiency of the pump is poor.
[0007]
(2) The discharge fluid is introduced only into one discharge-side back pressure groove provided on one side wall portion of both discharge-side back pressure grooves provided on both side wall portions of the pump body. For this reason, the rotor receives the fluid pressure introduced into one discharge side back pressure groove provided on one side wall portion only from one side inside the pump body and is pressed to the other side wall portion, and the other side. There is a risk of seizing and uneven wear with the side wall portion.
[0008]
An object of the present invention is to provide a variable displacement pump in which the tip of a vane is stably slidably contacted with the inner periphery of a cam ring, no collision noise with the cam ring is generated, and the discharge efficiency of the pump is improved. This is to prevent seizure and uneven wear with the side wall portion of the steel plate.
[0009]
[Means for Solving the Problems]
The invention of claim 1 is fixed to a pump shaft inserted into a pump body and is rotationally driven, and a rotor that accommodates a plurality of vanes in a holding groove so as to be movable in a radial direction,
A cam ring that is supported by a fitting hole in the pump body so as to be movable and displaceable, and that forms a pump chamber with the outer periphery of the rotor, and is provided on both side walls sandwiching the rotor and cam ring of the pump body. Provided on the suction side opening that opens to the suction side region, the discharge side opening that opens to the discharge side region, and the side wall of the pump body, along the rotation trajectory of the base end of the holding groove that holds the vane of the rotor A suction side back pressure groove corresponding to the suction side region of the pump chamber and a discharge side back pressure groove corresponding to the discharge side region. The rotor is driven to rotate by the pump shaft, and the tip of the vane The working fluid sucked from the suction side opening into the pump chamber is discharged from the discharge side opening, and the discharge fluid from the discharge side opening is discharged to the suction side back pressure groove and the discharge side of both side walls of the pump body. Parallel to each of the back pressure grooves A variable displacement pump to be introduced, wherein an introduction path for introducing the discharge fluid into the discharge-side back pressure groove is formed by introduction grooves formed in both side walls of the pump body, and a plurality of both sides of the pump body are provided on the side walls. An introduction groove is provided, and among the plurality of introduction grooves provided on each side wall , an angle formed by two adjacent introduction grooves is set to be different from an angle formed by two other adjacent introduction grooves, The timing when each of the plurality of vanes passes through each of the plurality of introduction grooves as the rotor rotates is made different from each other.
[0010]
According to a second aspect of the present invention, in the first aspect of the present invention, the holding groove for holding the vane of the rotor is arranged on a straight line passing through the center of the rotor, and the introduction grooves provided on both side walls of the pump body are provided. , And arranged so as to cross a straight line passing through the center of the rotor .
[0011]
According to a third aspect of the present invention, in the first or second aspect of the invention, the position of the introduction groove provided on one side wall portion and the position of the introduction groove provided on the other side wall portion in a side view of the pump body are determined. The rotation direction of the rotor is different .
[0012]
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects , the suction-side back pressure groove and the discharge-side back pressure groove are separated on one side wall portion of the pump body, and the other side wall portion is separated. The suction-side back pressure groove and the discharge-side back pressure groove are connected .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
1 is a sectional view showing a variable displacement pump, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a front view showing a side plate, FIG. 4 is a front view showing a cover, and FIG. It is a schematic diagram which shows a pump.
[0016]
The variable displacement pump 10 is a vane pump that serves as a hydraulic pressure generation source for a hydraulic power steering device of an automobile, and has a large discharge flow rate so that a large steering assist force can be obtained when the automobile having a low rotational speed is stopped or traveled at a low speed. The discharge flow rate is controlled to be equal to or less than a certain amount so as to reduce the steering assist force during high-speed driving with a high number, and the steering assist force required for the power steering device can be generated.
[0017]
In the variable displacement pump 10, a pump body 11 is constituted by a housing 12, a side plate 13 and a cover 14. The variable displacement pump 10 has a side plate 13 fitted in the back side of the recess 12A of the housing 12, a cover 14 fitted in the opening side of the recess 12A, and the housing 12, side plate 13 and cover 14 are not shown. It is assembled and constructed in a state where it is positioned in the rotational direction by the rotation preventing means.
[0018]
The variable displacement pump 10 has a rotor 22 that is fixed to a pump shaft 21 inserted into the pump body 11 and driven to rotate. In the recess 12 </ b> A of the housing 12, the rotor 22 is disposed between the side plate 13 that is one side wall portion of the pump body 11 and the cover 14 that is the other side wall portion. The variable displacement pump 10 accommodates each of the plurality of vanes 24 in holding grooves 23 provided at a plurality of circumferential positions of the rotor 22 and holds the vanes 24 so as to be movable in the radial direction (radial direction). The pump shaft 21 is rotatably supported by bearings 21 </ b> A and 21 </ b> B provided on the housing 12 and a bearing 21 </ b> C provided on the cover 14. Reference numeral 25 denotes an oil seal.
[0019]
In the variable displacement pump 10, an adapter ring 26 is fitted in an intermediate portion of the recess 12 </ b> A of the housing 12 constituting the pump body 11. The adapter ring 26 is sandwiched between the side plate 13 and the cover 14 and is held in a state of being positioned in the rotational direction by a fulcrum pin 27 engaged with the side plate 13 and the cover 14.
[0020]
The variable capacity pump 10 has a cam ring 28 fitted in a fitting hole 26 </ b> A of an adapter ring 26 fitted in the recess 12 </ b> A of the pump body 11. The cam ring 28 is disposed between the one side plate 13 of the pump body 11 and the other cover 14. The cam ring 28 surrounds the rotor 22 with a certain amount of eccentricity with the rotor 22, and forms a pump chamber 29 between the side plate 13 and the cover 14 and between the outer periphery of the rotor 22. As will be described later, the cam ring 28 is supported by the fulcrum pin 27 so as to be movable and displaceable (swinging) in the fitting hole 26A of the adapter ring 26 so that the volume (pump capacity) of the pump chamber 29 can be changed. The
[0021]
The variable capacity pump 10 has arc-shaped suction side openings 31 </ b> A and 31 </ b> B that open in the suction side region of the pump chamber 29 in each of the side plate 13 and the cover 14 on both sides of the rotor 22 and the cam ring 28 of the pump body 11. . The suction fluid flowing from the tank passes through the suction side passage 32 provided in the cover 14 and is supplied to the pump chamber 29 from the suction side opening 31B.
[0022]
The variable displacement pump 10 has arc-shaped discharge side openings 41 </ b> A and 41 </ b> B that open in the discharge side region of the pump chamber 29 in the side plate 13 and the cover 14 on both sides of the rotor 22 and the cam ring 28 of the pump body 11. . The discharge fluid pressure-fed from the pump chamber 29 passes through the discharge-side opening 41A and passes from the communication hole 42 provided in the side plate 13 to the discharge-side pressure chamber 43 formed in the innermost portion of the recess 12A of the housing 12. Discharged.
The variable displacement pump 10 has a discharge flow rate control device 50.
[0023]
The discharge flow rate control device 50 allows a compression coil spring 52 housed in a spring chamber 51 provided in the housing 12 of the pump body 11 to pass through a spring hole 26A provided in the adapter ring 26 and press-contact the outer periphery of the cam ring 28. An urging force that maximizes the volume of the pump chamber 29 can be applied to the cam ring 28. The spring 52 is backed up by a cap 51 </ b> A that is screwed into the opening of the spring chamber 51.
[0024]
In the discharge flow rate control device 50, first and second fluid pressure chambers 54 </ b> A and 54 </ b> B are dividedly formed between the cam ring 28 and the adapter ring 26. That is, the first fluid pressure chamber 54A and the second fluid pressure chamber 54B are divided between the cam ring 28 and the adapter ring 26 by the fulcrum pin 27 and the seal material 55 provided at the axially symmetric position.
[0025]
The discharge flow rate control device 50 is provided with a metering orifice (not shown) in the middle of the discharge path of the discharge fluid pumped from the pump chamber 29 of the variable capacity pump 10, and switches the high-pressure fluid upstream of the metering orifice. By the switching operation of the valve device 60 (operation in which the spool switching valve 62 moves to the right in FIG. 2), the low pressure fluid downstream of the metering orifice is guided to the second fluid pressure chamber 54B. . The switching valve device 60 has a spool switching valve 62 in a valve chamber 61 provided in the housing 12 of the pump body 11, and operates the switching valve 62 by a pressure difference on the downstream side of the metering orifice. A fluid pressure upstream of the metering orifice is introduced into the one-end side chamber of the switching valve 62. In the other end side chamber of the switching valve 62, a fluid pressure on the downstream side of the metering orifice is introduced, and a compression coil spring 63 that biases the switching valve 62 to the left side in FIG.
[0026]
Therefore, the discharge flow rate characteristics of the pump 10 provided with the discharge flow rate control device 50 are as follows.
[0027]
(1) In a low-speed traveling region of an automobile in which the rotational speed of the pump 10 is low, the pressure of the fluid upstream from the metering orifice that is discharged from the pump chamber 29 and reaches the one end side chamber of the switching valve device 62 is still low. 62 is located at the original position, and the cam ring 28 maintains the original state biased by the spring 52. For this reason, the discharge flow rate of the pump 10 increases in proportion to the rotational speed.
[0028]
(2) When the rotational pressure of the pump 10 increases and the pressure of the fluid upstream from the metering orifice that is discharged from the pump chamber 29 and reaches the one end side chamber of the switching valve 62 increases, the switching valve device 62 It moves to the right side of FIG. 2 against the urging force and guides this high-pressure fluid to the first fluid pressure chamber 54A. As a result, the cam ring 28 moves due to the differential pressure between the pressures acting on the first fluid pressure chamber 54A and the second fluid pressure chamber 54B, and the volume of the pump chamber 29 is gradually reduced. Therefore, the discharge flow rate of the pump 10 can maintain a constant large flow rate by offsetting the increase in the flow rate due to the increase in the rotation rate and the decrease in the flow rate due to the volume reduction of the pump chamber 29 with respect to the increase in the rotation rate. it can.
[0029]
However, in the variable displacement pump 10, as shown in FIGS. 1 to 5, the base end portion 23 </ b> A of the holding groove 23 that holds the vane 24 of the rotor 22 in each of the side plate 13 and the cover 14 of the pump body 11. Are provided with arcuate suction-side back pressure grooves 70A and 70B over a range corresponding to the suction-side region of the pump chamber 29.
[0030]
Further, in each of the side plate 13 and the cover 14 of the pump body 11, the portion along the rotation locus of the base end portion 23 </ b> A of the holding groove 23 that holds the vane 24 of the rotor 22 corresponds to the discharge side region of the pump chamber 29. The discharge side back pressure grooves 80A and 80B have a circular arc shape over a range to be covered.
[0031]
In the suction-side back pressure groove 70 </ b> A provided in the side plate 13 of the pump body 11, one or more discharge fluids discharged from the discharge-side opening 41 </ b> A of the side plate 13 into the discharge-side pressure chamber 43 are provided in the side plate 13. It introduces from the introduction holes 71-73 (three in this embodiment).
[0032]
In the discharge side back pressure grooves 80A and 80B provided in the side plate 13 and cover 14 of the pump body 11, the discharge fluid discharged to the discharge side openings 41A and 41B of the side plate 13 and cover 14 is sucked back pressure grooves. It introduces from one or more (three in this embodiment) introduction paths 81A to 83A and 81B to 83B provided in the side plate 13 and the cover 14 without going through the 70A and 70B.
[0033]
In this embodiment, the introduction paths 81A to 83A are formed by introduction grooves formed on the surface facing the rotor 22 of the side plate 13, and the introduction paths 81B to 83B are formed on the surface facing the rotor 22 of the cover 14. Is formed by.
[0034]
Further, each of the introduction grooves 81 </ b> A to 83 </ b> A provided on the side plate 13 and each of the introduction grooves 81 </ b> B to 83 </ b> B provided on the cover 14 are arranged on a straight line that does not pass through the center of the rotor 22. At this time, the holding groove 23 of the rotor 22 in which the vanes 24 are held is arranged on a straight line passing through the center of the rotor 22.
[0035]
Further, when a plurality of introduction grooves 81A to 83A are provided in the side plate 13, when a vane 24 passes (or reaches) a position corresponding to one introduction groove (for example, 81A), the other vanes 24 are other It does not pass (or reach) the position corresponding to the introduction groove (for example, 82A, 83A). When a plurality of introduction grooves 81B to 83B are provided in the cover 14, when a certain vane 24 passes (or reaches) a position corresponding to one introduction groove (for example, 81B), the other vane 24 has another introduction groove. It does not pass (or reach) a position corresponding to (for example, 82B, 83B).
[0036]
Further, the introduction grooves 81A to 83A provided in the side plate 13 and the introduction grooves 81B to 83B provided in the cover 14 are arranged so as not to overlap each other in a side view of the pump body 11 (FIGS. 2 to 4).
[0037]
In the side plate 13 of the pump body 11, the suction side back pressure groove 70A and the discharge side back pressure groove 80A are separated. In the cover 14 of the pump body 11, the suction side back pressure groove 70 </ b> B and the discharge side back pressure groove 80 </ b> B are connected by a communication path 90. In the present embodiment, the communication path 90 is formed by a communication groove formed on the surface of the cover 14 facing the rotor 22, and connects the arc end of the suction side back pressure groove 70 </ b> B and the arc end of the discharge side back pressure groove 80 </ b> B. A circular arc connected on the same circumference.
[0038]
Therefore, in the variable displacement pump 10, the rotor 22 is rotationally driven by the pump shaft 21, and the vane 24 held in the inner groove 23 of the rotor 22 has centrifugal force and back pressure grooves 70 </ b> A and 70 </ b> B, back pressure grooves. When rotating by being pressed against the inner periphery of the cam ring 28 by the fluid pressure introduced into 80A and 80B, the volume surrounded by the cam ring 28 between the adjacent vanes 24 and the cam ring 28 is increased in the suction side region of the pump chamber 29. The fluid is sucked from the suction side openings 31A and 31B. In the discharge side region, the volume enclosed by the adjacent vanes 24 and the cam ring 28 is reduced with rotation to discharge the working fluid to the discharge side openings 41A and 41B, and this discharge fluid is supplied to the power cylinder of the hydraulic power steering device. .
[0039]
According to this embodiment, there are the following operations.
(Operation corresponding to claim 1)
(a) The discharge fluid from the pump chamber 29 is not supplied to the suction-side back pressure grooves 70A and 70B, but is discharged to the discharge-side back pressure grooves 80A and 80B on both side walls (side plate 13 and cover 14) of the pump body 11. Introduced. Accordingly, the high-pressure discharge fluid is introduced into the discharge-side back pressure grooves 80A and 80B, and the vane 24 is reliably ejected from the holding groove 23 of the rotor 22 in the discharge-side region of the pump chamber 29, so that the tip of the vane 24 Is slidably pressed against the inner circumference of the cam ring 28. The collision efficiency between the tip of the vane 24 and the cam ring 28 is not generated, and the discharge efficiency of the pump 10 can be improved.
[0040]
(b) Discharge fluid is introduced into both discharge-side back pressure grooves 80A and 80B provided on both side walls (side plate 13 and cover 14) of the pump body 11. Accordingly, the rotor 22 receives fluid pressures that are introduced into both the discharge-side back pressure grooves 80A and 80B provided on both side walls inside the pump body 11 and are balanced with each other. Seizure and uneven wear between the rotor 22 and the side wall (side plate 13 and cover 14) of the pump body 11 can be prevented.
[0041]
(c) The introduction paths 81A to 83A and 81B to 83B for introducing the discharge fluid into the discharge side back pressure grooves 80A and 80B are formed by the introduction grooves formed on both side walls (side plate 13 and cover 14) of the pump body 11. Been formed. Therefore, as compared with the case where the introduction path is perforated inside the both side walls of the pump body 11, the processing becomes easier and the productivity can be improved.
(d) When a plurality of introduction grooves 81A to 83A and 81B to 83B are provided on both side walls (side plate 13 and cover 14) of the pump body 11, a vane 24 passes through a position corresponding to one introduction groove. The other vanes 24 do not pass through the positions corresponding to the other introduction grooves. Therefore, pulsation of the fluid discharge pressure discharged from the pump chamber 29 can be prevented.
[0042]
(Operation corresponding to claim 2 )
(e) The introduction grooves 81 </ b> A to 83 </ b> A and 81 </ b> B to 83 </ b> B provided on both side walls (side plate 13 and cover 14) of the pump body 11 are arranged on a straight line that does not pass through the center of the rotor 22. Therefore, when the rotor 22 rotates, the vane 24 and the introduction grooves 81A to 83A and 81B to 83B are prevented from being caught, and the rotation of the rotor 22 and the movement of the vane 24 can be ensured.
[0044]
(Operation corresponding to claim 3 )
(f) In a side view of the pump body 11, the introduction grooves 81A to 83A provided on one side wall (side plate 13) and the introduction grooves 81B to 83B provided on the other side wall (cover 14) do not overlap. Are arranged as follows. Therefore, pulsation of the fluid discharge pressure discharged from the pump chamber 29 can be prevented.
[0045]
(Operation corresponding to claim 4 )
(g) The suction side back pressure groove 70A and the discharge side back pressure groove 80A are separated at one side wall portion (side plate 13 ) of the pump body 11, and the suction side back pressure groove is formed at the other side wall portion (cover 14). 70B and the discharge side back pressure groove 80B were connected. Therefore, the discharge fluid is introduced into the suction side back pressure groove 70A of one side wall (side plate 13) without passing through the discharge side back pressure groove 80A, and the suction side back pressure of the other side wall (cover 14) is introduced. The discharge fluid can be introduced into the groove 70B via the discharge-side back pressure groove 80B. The discharge fluid can be introduced into both the suction side back pressure grooves 70A and 70B and both the discharge side back pressure grooves 80A and 80B with a simple configuration on both side walls.
[0046]
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. Is included in the present invention.
[0047]
【The invention's effect】
As described above, according to the present invention, in the variable displacement pump, the tip of the vane is stably slidably contacted with the inner periphery of the cam ring, no collision noise with the cam ring is generated, and the discharge efficiency of the pump is improved. Seizure and uneven wear between the rotor and the side wall of the pump body can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a variable displacement pump.
FIG. 2 is a sectional view taken along line II-II in FIG.
FIG. 3 is a front view showing a side plate.
FIG. 4 is a front view showing a cover.
FIG. 5 is a schematic diagram showing a variable displacement pump.
[Explanation of symbols]
10 Variable displacement pump 11 Pump body 13 Side plate (one side wall)
14 Cover (the other side wall)
21 pump shaft 22 rotor 23 holding groove 24 vane 26 adapter ring 26A fitting hole 28 cam ring 29 pump chamber 31A, 31B suction side opening 41A, 41B discharge side opening 70A, 70B suction side back pressure groove 80A, 80B discharge side back pressure groove 81A-83A introduction path (introduction groove)
81B-83B Introduction path (introduction groove)
90 connection

Claims (4)

A rotor which is fixed to a pump shaft inserted into the pump body and is rotationally driven, and which holds a plurality of vanes in a holding groove so as to be movable in a radial direction;
A cam ring that is supported by the fitting hole in the pump body so as to be movable and displaceable, and that forms a pump chamber with the outer periphery of the rotor;
A suction side opening that opens to the suction side region of the pump chamber, a discharge side opening that opens to the discharge side region, provided on both side walls sandwiching the rotor and cam ring of the pump body;
A suction side back pressure groove corresponding to the suction side region of the pump chamber and a discharge side region are provided on the side wall portion of the pump body along the rotation trajectory of the base end portion of the holding groove for holding the vane of the rotor. A corresponding discharge-side back pressure groove,
The rotor is driven to rotate by the pump shaft, the tip of the vane is brought into sliding contact with the inner periphery of the cam ring, and the working fluid sucked into the pump chamber from the suction side opening is discharged from the discharge side opening.
A variable displacement pump that introduces the discharge fluid from the discharge side opening in parallel to each of the suction side back pressure groove and the discharge side back pressure grooves on both side walls of the pump body,
An introduction path for introducing the discharge fluid into the discharge-side back pressure groove is formed by introduction grooves formed on both side walls of the pump body,
A plurality of introduction grooves are provided on both side wall portions of the pump body, and among the plurality of introduction grooves provided on each side wall portion, an angle formed by two adjacent introduction grooves is between two other adjacent introduction grooves. A variable displacement pump that is set to be different from the angle formed, and that each of the plurality of vanes passes through each of the plurality of introduction grooves with the rotation of the rotor. A holding groove for holding the rotor vanes is disposed on a straight line passing through the center of the rotor;
The variable capacity pump according to claim 1, wherein the introduction grooves provided on both side walls of the pump body are arranged so as to intersect with a straight line passing through the center of the rotor.   The position of the introduction groove provided in one side wall part differs from the position of the introduction groove provided in the other side wall part with respect to the rotation direction of the rotor in a side view of the pump body. Variable displacement pump.   The suction side back pressure groove and the discharge side back pressure groove are separated at one side wall portion of the pump body, and the suction side back pressure groove and the discharge side back pressure groove are connected at the other side wall portion. The variable capacity pump in any one of -3.

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