JP2009074502A - Flow control valve for liquid pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow control valve for a liquid pump capable of sufficiently securing a flow passage cross section within a spool chamber with a short stroke and of suppressing energy loss. <P>SOLUTION: The flow control valve for the liquid pump is provided with a spool 19 which has a seal part 19a provided in the spool chamber 17, facing a pressure chamber 10, brought into sliding contact with an inner wall face 17a of the spool chamber 17 and having a large diameter and a narrow part 19b continued from the seal part 19a and having a diameter smaller than that of the seal part 19a and is moved axially inside the spool chamber 17 in accordance with pump discharge pressure to open/close a drain flow passage 22; and a recess part 25 which is formed in a position located on the inner wall face 17a of the spool chamber 17 and overlapped with the drain flow passage 22 in the axial direction of the spool chamber 17 and has axial length L longer than axial length M of the seal part 19a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention belongs to the technical field of a flow control valve that maintains the discharge rate of a liquid pump constant.

As this type of flow control valve, for example, a spool is housed in a spool chamber communicating with the pump discharge side, and the drain flow path communicating between the spool chamber and the pump suction side is opened and closed by the axial movement of the spool. Thus, there is disclosed one that recirculates a part of the pump discharge amount to the pump suction side (see, for example, Patent Document 1).
Japanese Utility Model Publication No. 03-50587

  However, in the above prior art, since the rate of increase in the flow passage cross-sectional area in the spool chamber is low with respect to the stroke amount of the spool, the flow passage cross-sectional area necessary for maintaining the pump discharge pressure constant is ensured. Therefore, it is necessary to increase the spool stroke. For this reason, there is a problem that energy loss is large because the pump internal pressure must be set high.

  The present invention has been made paying attention to the above-mentioned problem, and the purpose thereof is a liquid that can sufficiently secure a cross-sectional area of the flow passage in the spool chamber with a small stroke amount and can suppress energy loss. It is to provide a flow control valve for a pump.

In order to achieve the above object, in the flow control valve of the liquid pump of the present invention,
A spool having a large-diameter seal portion facing the discharge side of the pump unit and in sliding contact with the inner wall surface of the spool chamber, and a constriction having a smaller diameter than the seal portion, which is continuous from the seal portion;
An inner wall surface of the spool chamber, which is formed at a position overlapping the drain flow path and the spool chamber in the axial direction, and has a recess that is longer in the axial direction than the seal portion;
It is characterized by providing.

  Therefore, in the present invention, when the discharge side of the pump unit and the drain flow path communicate with each other due to the movement of the spool, the spool chamber has a drain flow path from the front side of the seal portion of the spool (discharge side of the pump unit). In addition to the path toward the top, a path is formed from the recess toward the drain flow path via a space formed between the inner wall surface of the spool chamber and the constricted portion of the spool.

  For this reason, the flow passage cross-sectional area in the spool chamber can be secured with a smaller stroke amount of the spool as compared with the conventional technique in which the liquid is recirculated only from the path from the front side of the seal portion of the spool to the drain flow passage. , Energy loss can be suppressed.

  Hereinafter, the best mode for realizing the flow control valve of the liquid pump of the present invention will be described based on Examples 1 to 3 shown in the drawings.

First, the configuration will be described.
FIG. 1 is a side sectional view of an oil pump to which the flow control valve of the first embodiment is applied, and FIG. 2 is a front sectional view of the oil pump of the first embodiment.

[Configuration of pump unit]
A pump shaft 3 is supported via a bearing 4 in the shaft hole 2 of the pump casing 1. A cartridge 5 that performs a pumping action is assembled at the tip of the pump shaft 3. The cartridge 5 includes a cam ring 6, a rotor 7, a vane 8, and two bushes 9a and 9b. When the pump shaft 3 rotates, the vane 8 fitted in the groove of the rotor 7 jumps out in the centrifugal force direction and is cam ring. 6 is slidably brought into contact with the inner periphery of the cylinder 6, and the pump action is performed by changing the volume between the vanes 8 and 8 (see FIG. 2).

  A cover 11 that covers the cartridge 5 and forms the pressure chamber 10 on the outer peripheral side of the cartridge 5 is fixed to the end surface of the pump casing 1. The pressure chamber 10 is formed in an annular shape between the inner peripheral surface 11a of the cover 11 and the outer peripheral surface of the cartridge 5, and oil that has been pumped by the cartridge 5 is received in the pressure chamber 10 by the bush 9a. , 9b through the discharge passage 12.

  A suction hole 13 and a discharge hole 14 are formed in the pump casing 1. The suction hole 13 introduces oil into the cartridge 5. On the other hand, the discharge hole 14 communicates with the pressure chamber 10 via the orifice 15 formed in the bush 9b and the discharge path 12, and guides the pumped oil to an unillustrated operating device (for example, a power steering device). To do.

[Configuration of flow control valve]
A flow rate control valve 16 is disposed in the pump casing 1 along the axial direction of the pump shaft 3. The flow control valve 16 is configured by accommodating a spool 19 and a spring 20 that presses the back of the spool 19 in a spool chamber 17 formed in parallel to the pump shaft 3 on the radially outer peripheral side of the pump casing 1. Yes.

  The spool chamber 17 is arranged substantially in series with the pressure chamber 10, and the position of the outer edge in the radial direction is set to be substantially the same as the inner peripheral surface 11 a of the cover 11, and one end thereof is directly in the pressure chamber. 10 is opened. The spool chamber 17 is formed with a pressure introduction hole 21 and a rain channel 22. Among these, the pressure introducing hole 21 communicates the spool chamber 17 and the discharge hole 14, and is configured to introduce oil after passing through the orifice 15 to the back side of the spool chamber 17.

  On the other hand, in the drain flow path 22, when the differential pressure across the orifice 15 increases and the spool 19 moves a predetermined amount to the right in the figure, the spool chamber 17 and the suction hole 13 communicate with each other, and a part of the discharged liquid is pumped out. From the side (pressure chamber 10) to the suction hole 13 side (pump suction side).

  FIG. 3 is a front sectional view of the oil pump showing the details of the drain flow path 22. The drain flow paths 22 are provided as a pair of right and left, and each drain flow path 22 is formed independently from the upstream side to the downstream side. Each of them communicates with the suction hole 13 through a groove 23 and communicates with the inside of the cartridge 5 through a suction port (not shown) formed in the liquid reservoir 24 and the bush 9b. Further, the opening ends 22 a and 22 a on the spool chamber 17 side of the drain passages 22 and 22 are disposed at 45 ° left and right in the circumferential direction from the lower end of the spool chamber 17.

  4 is a cross-sectional view taken along line S4-S4 of FIG. 3. In the spool chamber 17, a recess 25 is formed at a position overlapping the opening of the drain passages 22 and 22 in the axial direction of the spool chamber 17. FIG. The recess 25 is located at the upper end of the spool chamber 17.

  The spool 19 has a large-diameter seal portion 19a that faces the pressure chamber 10 and is in sliding contact with the inner wall surface 17a of the spool chamber 17, and a constricted portion 19b that is continuous from the seal portion 19a and has a smaller diameter than the seal portion 19a. Yes. The axial length of the seal portion 19 a is set longer than the inner diameter of the open end 22 a of the drain flow path 22. The axial length N of the constricted portion 19b is set longer than the axial length M of the seal portion 19a. Further, the axial length M of the seal portion 19 a is formed shorter than the axial length L of the recess 25.

  As shown in the S5-S5 cross-sectional view of FIG. 5, the recess 25 is processed by inserting a circular cutter 26 having an outer diameter smaller than the inner diameter of the spool chamber 17 in the axial direction of the spool chamber 17 and cutting it once. can do. Here, the cutter 26 having the same length as the axial length of the recess 25 is used. By forming the recess 25 by this method, the axial position of the recess 25 can be freely set according to the position of the drain flow path 22.

Next, the operation will be described.
[Spool chamber flow path cross-section increasing action by recess and constriction]
In the oil pump of the first embodiment, the pump discharge pressure increases to sufficiently compress the spring 20 that urges the spool 19 until the pump speed (the speed of the pump shaft 3) reaches a predetermined speed. do not do. Therefore, the drain flow path 22 is blocked by the spool 19. In this state, the amount of oil flowing out through the discharge hole 14 increases in proportion to the increase in the pump rotational speed.

  FIG. 6A is a schematic diagram showing a state in which the drain flow path 22 is closed in the flow rate control valve of the first embodiment, and the cross sections of the pressure chamber 10 (region A) and the drain flow channel 22 (region C) Is constant, but when the drain channel 22 is closed, the channel cross section of the spool chamber 17 (region B) is zero (FIG. 6B).

  When the pump speed reaches a predetermined speed, the differential pressure across the orifice 15 increases. Therefore, the spool 19 moves by pressing and contracting the spring 20 to open the drain flow path 22 into the spool chamber 17. Thereby, a part of the pump discharge amount is returned to the suction hole 13 side via the drain flow path 22, and the remaining part of the pump discharge amount flows out from the discharge hole 14.

  At this time, in the first embodiment, the recessed portion 25 is formed at a position overlapping the drain flow path 22 of the spool chamber 17 in the axial direction, and the spool 19 is provided with a narrow-diameter constricted portion 19b. For this reason, the drain flow path 22 and the recessed portion 25 communicate with each other through the space between the constricted portion 19 b and the inner wall surface 17 a of the spool chamber 17 and have the same pressure.

  Here, since the axial length of the constricted portion 19b is set to be longer than the axial length of the seal portion 19a, the recess 25 is blocked by the seal portion 19a even when the spool 19 has a large stroke. The communication state between the concave portion 25 and the constricted portion 19b is ensured. Further, since the axial length of the seal portion 19a is shorter than the inner diameter of the opening end 22a of the drain channel 22, the drain channel 22 is not blocked by the seal portion 19a, and the constricted portion 19b and the spool chamber 17 are not closed. A communication state between the space formed between the inner wall surface 17a and the drain channel 22 is ensured.

  As a result, as shown in FIG. 6 (c), the spool chamber 17 has a spool 1 from the recess 25 in addition to the path 1 from the seal 19a front side (pressure chamber 10 side) of the spool 19 to the drain flow path 22. A path 2 toward the drain flow path 22 is formed through a space formed between the inner wall surface 17a of the chamber 17 and the constricted portion 19b.

  For this reason, as is apparent from FIG. 6 (d), the prior art in which oil is circulated only from the path 1 from the front side of the seal portion of the spool to the drain flow path (FIGS. 6 (e) and 6 (f)). As compared with, the total flow path cross-sectional area is increased by the flow path cross-sectional integral of the path 2 with the same stroke amount, and a sufficient flow path cross-sectional area can be secured with a smaller stroke amount of the spool 19. Therefore, since the stroke amount of the spool 19 can be kept small, the pump internal pressure can be set low, and the oil can be internally circulated with small energy.

[Discharge flow stabilization effect by reducing pump internal pressure]
When the diameter of the orifice 15 on the discharge side is constant, the pump internal pressure decreases, so that the NQ characteristic, which is the characteristic of the discharge flow rate Q with respect to the pump rotational speed N, can be stabilized as shown in FIG. An excessive increase in the discharge flow rate accompanying the increase in the number can be prevented.

[Valve performance improvement effect by constriction]
In the first embodiment, since the constricted portion 19 b is formed in the spool 19, the contamination of the spool chamber 17 (foreign matter mixed into the hydraulic oil when the pump is driven) is improved, and the spool lock is generated by the contamination in the spool chamber 17. It is possible to prevent oil leakage due to galling of the pump due to an increase in internal pressure or deterioration with time of seals.

[Spool balance improvement]
In the first embodiment, since the two independent and independent drain flow paths 22 and 22 are provided, the force of pressing the spool 19 against the inner wall surface 17a of the spool chamber 17 is reduced as compared with the case where there is one drain flow path. Uneven wear of the spool 19 and the spool chamber 17 can be reduced. Further, by forming the two drain passages 22 and 22 independently without joining or branching, the flow of the liquid in the drain passages 22 and 22 is stabilized, resulting in oil agitation and cavitation. Generation of abnormal noise can be suppressed.

  In the first embodiment, the opening ends 22 a and 22 a of the drain flow paths 22 and 22 are arranged at a position of 45 ° in the circumferential direction from the lower end of the spool chamber 17, and the concave portion 25 is arranged at the upper end portion of the spool chamber 17. did. That is, the opening ends 22a and 22a are disposed within a range of less than 180 ° in the circumferential direction of the spool chamber 17, and the recess 25 is disposed within a range of 180 ° in the circumferential direction opposite to the opening ends 22a and 22a. The oil flow in the spool chamber 17 is dispersed on both sides in the radial direction of the spool chamber 17, so that the balance of the spool 19 is improved and the inclination in the axial direction can be kept small. For this reason, a hysteresis characteristic improves and durability can be improved.

  Here, the inner wall surface 17a of the spool chamber 17 and the constricted portion 19b are connected from the recess 25 to the channel cross section of the path 1 from the seal portion 19a front side (pressure chamber 10 side) of the spool 19 to the drain channel 22. Since the flow path cross section of the path 2 that goes to the drain flow path 22 via the space formed therebetween is larger, when there is one drain flow path, the spool 19 is inclined by receiving a force from top to bottom. , Balance becomes worse. On the other hand, in Example 1, since the two drain flow paths 22 and 22 were provided with respect to one recessed part 25, the inclination of the spool 19 can be suppressed and balance property can be improved more.

Next, the effect will be described.
The flow control valve of the oil pump according to the first embodiment has the following effects.

  (1) A large-diameter seal portion 19a that is provided in the spool chamber 17 and faces the pressure chamber 10 and is in sliding contact with the inner wall surface 17a of the spool chamber 17, and a constricted portion that is continuous from the seal portion 19a and has a smaller diameter than the seal portion 19a. 19b, a spool 19 that opens and closes the drain passage 22 by moving in the spool chamber 17 in the axial direction according to the pump discharge pressure, and an inner wall surface 17a of the spool chamber 17, And a recess 25 having an axial length L that is longer than the axial length M of the seal portion 19a. Thereby, the flow path cross-sectional area in the spool chamber can be secured with a small stroke amount of the spool, and energy loss can be suppressed.

  (2) The opening end 22a of the drain passage 22 is disposed within a range of less than 180 ° in the circumferential direction of the spool chamber 17, and the recess 25 is disposed within a range of 180 ° in the circumferential direction opposite to the opening end 22a. did. As a result, the flow of oil flowing in the spool chamber 17 is dispersed on both sides in the radial direction of the spool chamber 17, improving the balance of the spool 19 and improving the durability.

  (3) Since the drain flow path 22 is a plurality of independent flow paths from the upstream side to the downstream side, the flow of the liquid in the drain flow paths 22 and 22 is stabilized, resulting in oil agitation and cavitation. Generation of abnormal noise can be suppressed.

  (4) Since the drain flow path 22 has two flow paths and one recess 25 is provided, the inclination of the spool 19 can be suppressed and the balance can be further improved.

  (5) Since the concave portion 25 is formed by inserting the cutter 26 from the axial direction of the spool chamber 17, the axial position of the concave portion 25 can be freely set according to the position of the drain flow path 22.

  (6) Since the axial length N of the seal portion 19a is set to be shorter than the inner diameter of the open end 22a of the drain channel 22, the drain channel 22 can be prevented from being blocked by the seal portion 19a, A communication state with the drain channel 22 can be ensured.

  The flow control valve according to the second embodiment is an example in which the concave portion is disposed at a position facing the drain flow path in the radial direction of the spool chamber.

FIG. 8 is a front cross-sectional view of an oil pump to which the flow control valve of the second embodiment is applied. Two concave portions 27 are provided at opposite positions.
Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

  As shown in FIG. 9, the recess 27 of the second embodiment is simultaneously drilled from the drain flow path 22 side when forming the hole for the drain flow path 22. By forming the concave portion 27 by this method, the number of processes can be reduced and the work can be facilitated.

[Spool balance improvement]
In the second embodiment, since the two concave portions 27 and 27 are provided symmetrically with the two drain flow paths 22 and 22, the oil flowing into the spool chamber 17 from the pressure chamber 10 has an equal pitch (45 °) around the spool 19. The pitch 19) is distributed in four places, so that the balance of the spool 19 can be improved and the durability can be improved.

Next, the effect will be described.
In addition to the effects (1) to (3) and (6) of the first embodiment, the flow control valve of the oil pump of the second embodiment has the effects listed below.

  (7) Since the concave portion 27 is disposed at a position facing the drain passage 22 and the spool chamber 17 in the radial direction, the balance of the spool 19 can be improved and the durability can be improved.

  (8) Since the recess 27 is formed by drilling from the drain channel 22 side, the recess 27 can be easily processed using the existing drain channel 22.

  (9) Since the recess 27 is formed at the same time as the drain flow path 22, the number of processing can be reduced as compared with the case where each is formed separately.

  The flow control valve of Example 3 is an example in which a recess is formed over the entire circumference of the spool chamber.

10 is a front sectional view of an oil pump to which the flow control valve of the third embodiment is applied, FIG. 11 is a sectional view taken along the line S11-S11 of FIG. 10, and in the third embodiment, the recess 28 is formed on the entire circumference of the spool chamber 17. It is formed over.
Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

  As shown in FIG. 12, the concave portion 28 of the third embodiment inserts a circular cutter 29 having an outer diameter smaller than the inner diameter of the spool chamber 17 in the axial direction of the spool chamber 17 from the pressure chamber 10 side. The inner wall surface 17a of the spool chamber 17 is cut by moving the tip portion of the spool chamber 17 into a circular shape.

[Spool balance improvement]
In the flow control valve of the third embodiment, the oil that has flowed from the pressure chamber 10 into the spool chamber 17 flows through the entire circumference of the spool 19 due to the recesses 28 formed over the entire circumference of the spool chamber 17. It is possible to improve the balance and improve durability.

Next, the effect will be described.
In addition to the effects (1), (3), (5), (6) of the first embodiment, the flow control valve of the oil pump of the third embodiment has the following effects.

  (10) Since the recess 28 is formed over the entire circumference of the spool chamber 17, the balance of the spool 19 can be improved and the durability can be improved.

(Other examples)
The best mode for carrying out the present invention has been described based on the first to third embodiments. However, the specific configuration of the present invention is not limited to the configuration shown in the embodiments. For example, In Examples 1 to 3, an example in which two drain channels are provided is shown, but three or more drain channels may be provided.

It is side surface sectional drawing of the oil pump to which the flow control valve of Example 1 is applied. 1 is a front sectional view of an oil pump according to a first embodiment. 2 is a front sectional view of an oil pump showing details of a drain flow path 22 of Example 1. FIG. It is S4-S4 sectional drawing of FIG. It is S5-S5 sectional drawing of FIG. It is a schematic diagram which shows the opening / closing state in the flow control valve of Example 1, and the change of the flow-path cross-sectional area of a spool chamber. It is a characteristic view of the discharge flow rate Q with respect to the pump rotation speed N of Example 1. It is front sectional drawing of the oil pump to which the flow control valve of Example 2 is applied. It is S9-S9 sectional drawing of FIG. It is front sectional drawing of the oil pump to which the flow control valve of Example 3 is applied. It is S11-S11 sectional drawing of FIG. It is S12-S12 sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pump casing 2 Shaft hole 3 Pump shaft 4 Bearing 5 Cartridge 6 Cam ring 7 Rotor 8 Vane 9a, 9b Bush 10 Pressure chamber 11 Cover 11a Inner peripheral surface 12 Discharge path 13 Suction hole 14 Discharge hole 15 Orifice 16 Flow control valve 17 Spool chamber 17a Inner wall surface 19 Spool 19a Seal portion 19b Constriction portion 21 Pressure introducing hole 22 Drain flow path 22a Open end 23 Groove 24 Liquid reservoir 25 Recess 26 Cutter 27 Drain flow path 27 Recess 28 Recess 29 Recess 29 Cutter

Claims (10)

In a flow control valve provided in a liquid pump having a pump unit for sucking and pressurizing liquid,
A spool chamber formed in the pump housing and in communication with the discharge side of the pump unit;
A drain channel that opens into the spool chamber and communicates with the suction side of the pump unit;
A large-diameter seal portion that is provided in the spool chamber and faces the discharge side of the pump unit and is in sliding contact with the inner wall surface of the spool chamber; and a constricted portion that is continuous from the seal portion and has a smaller diameter than the seal portion. A spool that opens and closes the drain flow path by axially moving in the spool chamber according to the discharge pressure of the pump unit;
An inner wall surface of the spool chamber, formed at a position overlapping the drain flow path and the spool chamber in the axial direction, and a recess longer in the axial direction than the seal portion;
A flow rate control valve for a liquid pump. In the flow control valve of the liquid pump according to claim 1,
An opening end of the drain channel is disposed within a range of less than 180 ° in the circumferential direction of the spool chamber,
A flow rate control valve for a liquid pump, wherein the concave portion is arranged within a range of 180 ° in a circumferential direction opposite to the opening end. In the flow control valve of the liquid pump according to claim 1 or 2,
A flow rate control valve for a hydraulic pump, wherein the concave portion is disposed at a position facing the drain flow path in the radial direction of the spool chamber. In the flow control valve of the liquid pump according to any one of claims 1 to 3,
A flow rate control valve for a liquid pump, wherein the drain flow path is a plurality of independent flow paths from the upstream side to the downstream side. In the flow control valve of the liquid pump according to claim 4,
The drain channel is two channels,
A flow rate control valve for a liquid pump, wherein one recess is provided. In the flow control valve of the liquid pump according to any one of claims 1 to 5,
A flow rate control valve for a liquid pump, wherein the recess is formed over the entire circumference of the spool chamber. In the flow control valve of the liquid pump according to any one of claims 1 to 6,
A flow rate control valve for a liquid pump, wherein the recess is formed by inserting a cutter from the axial direction of the spool chamber. In the flow control valve of the liquid pump according to any one of claims 1 to 6,
A flow rate control valve for a liquid pump, wherein the recess is formed by drilling from the drain flow path side. The flow control valve of the liquid pump according to claim 8,
A flow rate control valve for a liquid pump, wherein the recess is formed simultaneously with the drain flow path. In the flow control valve of the liquid pump according to any one of claims 1 to 9,
A flow rate control valve for a liquid pump, wherein the axial length of the seal portion is set shorter than the inner diameter of the open end of the drain flow path.

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