JP2010144654A - Flow rate control valve of fluid pressure pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow rate control valve with high durability which prevents erosion from occurring, even when working fluid discharged by a flow pressure pump is under high pressure. <P>SOLUTION: The flow rate control valve 100 is disposed on a supply path 12 for conducting hydraulic oil discharged from a vane pump 101 as a fluid pressure pump to hydraulic equipment 10 and controls a flow rate of the hydraulic oil supplied to the hydraulic equipment 10. The flow rate control valve 100 has a spool 30 moving depending on pressure of the hydraulic oil discharged from the vane pump 101, and includes a spool valve 21 refluxing part of the hydraulic oil discharged from the vane pump 101 to a return path 33 communicating with a suction side of the vane pump 101. An annular groove 51 which can have gas contained in the hydraulic oil stay as air bubbles is provided on the wall surface of the spool 30 against which the hydraulic oil discharged from the vane pump 101 to reflux to the return path 33 collides, so that impact due to collision of the hydraulic oil is lessened. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flow rate control valve that controls the flow rate of a working fluid supplied from a fluid pressure pump to a fluid pressure device.

  2. Description of the Related Art Conventionally, fluid pressure devices that are driven using fluid pressure have been used for vehicles such as automobiles. Since the fluid pressure pump discharges the working fluid by the rotation of the engine, the flow rate of the working fluid increases in proportion to the engine speed. Therefore, in order to optimize the flow rate of the working fluid supplied to the fluid pressure device when the flow rate of the pressure oil discharged from the fluid pressure pump is excessive, the flow rate for adjusting the supply amount of the working fluid to the fluid pressure device A control valve is provided.

  The flow control valve includes a spool valve that opens and closes due to a pressure difference between the upstream side and the downstream side. When the spool valve is opened, a part of the working fluid discharged by the fluid pressure pump is returned to the oil tank to reduce the flow rate. Thereby, the flow rate sent to the fluid pressure device can be made smaller than the flow rate discharged by the fluid pressure pump.

Patent Document 1 discloses a power steering device that performs hydraulic control using a flow control valve.
JP-A-2005-112280

  However, since the working fluid discharged from the fluid pressure pump has a high pressure, the flow of the working fluid when the excess working fluid is returned to the oil tank on the low pressure side is high speed. For this reason, when the working fluid is recirculated to the oil tank, a large impact force is applied to the inside of the flow control valve due to the collision of the working fluid, which may cause erosion in part. In recent years, fluid pressure pumps have increased in pressure and capacity, and when the pressure of the working fluid is high and erosion occurs, the inside of the flow control valve may be damaged, and the function of the flow control valve may be affected.

  In view of the above problems, an object of the present invention is to provide a highly durable flow control valve that prevents erosion from occurring even if the working fluid discharged from the fluid pressure pump is at a high pressure. .

  The present invention is a flow rate control valve that is interposed in a supply passage that guides a working fluid discharged from a fluid pressure pump to a fluid pressure device, and controls the flow rate of the working fluid supplied to the fluid pressure device, A spool that moves in accordance with the pressure of the working fluid discharged from the pump returns a part of the working fluid discharged from the fluid pressure pump to a return passage that communicates with the suction side of the fluid pressure pump. A spool valve is provided, and a concave groove is provided on a wall surface of the spool on which the working fluid discharged from the fluid pressure pump and recirculated to the return passage collides so that gas contained in the working fluid can be stored as bubbles. And

  According to the present invention, the gas contained in the working fluid becomes bubbles and accumulates in the concave groove, and acts as a buffer when the working fluid collides with the wall surface of the spool valve. Therefore, since the working fluid collides via the bubbles, the impact caused by the collision of the working fluid can be reduced compared with the case where the working fluid directly collides with the inner wall surface of the flow control valve.

  Therefore, even if the working fluid discharged from the fluid pressure pump is high pressure, erosion can be prevented from occurring inside, and a highly durable flow control valve can be obtained.

  Hereinafter, the flow control valve 100 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of a side surface of a flow control valve 100 according to an embodiment of the present invention, in which a spool valve 21 is closed, and FIG. 2 is a cross-sectional view of a side surface of the flow control valve 100. The spool valve 21 is in an open state. In this embodiment, hydraulic pressure is used as the fluid pressure.

  The flow rate control valve 100 controls the flow rate of the working fluid supplied from the fluid pressure pump, which is a hydraulic pressure supply source, to the hydraulic device 10 to have a predetermined characteristic. In the present embodiment, a case where the fluid pressure pump is a vane pump 101 driven by an engine of a vehicle will be described. The hydraulic device 10 is, for example, a power steering device or a transmission mounted on a vehicle. The hydraulic device 10 corresponds to a fluid pressure device.

  Although not shown, the vane pump 101 is configured such that engine power is transmitted to an end portion of a drive shaft, and a rotor connected to the drive shaft rotates. The vane pump 101 includes a plurality of vanes provided so as to be capable of reciprocating in the radial direction with respect to the rotor, and a cam ring that accommodates the rotor and in which the tip of the vane slides on the inner cam surface as the rotor rotates. Prepare. The cam ring is an annular member whose inner peripheral cam surface has an elliptical shape, and a plurality of pump chambers partitioned by adjacent vanes are defined in the cam ring. The cam ring has a suction region that expands the volume of the pump chamber and a discharge region that contracts the volume of the pump chamber.

  In the suction region, the vane pump 101 sucks hydraulic oil by utilizing the fact that the internal pressure is lowered by gradually expanding the volume of the oil chamber. Further, in the discharge region, hydraulic oil is discharged by utilizing the fact that the internal pressure rises as the volume of the oil chamber gradually contracts.

  The flow rate control valve 100 is interposed in a supply passage 12 that guides the hydraulic oil discharged from the vane pump 101 to the hydraulic device 10, and supplies the hydraulic oil according to the differential pressure across the variable throttle 20. A spool valve 21 for returning the hydraulic oil in the passage 12 to the pump suction side and a relief valve 22 provided on the downstream side of the variable throttle 20 are provided.

  The variable throttle 20, the spool valve 21, and the relief valve 22 are housed inside the valve body 27, and a cap 28 is screwed into the opening of the valve body 27.

  A spool 30 is slidably inserted into a spool hole 31 provided in the valve body 27. The spool hole 31 communicates with a pump port 32 into which the hydraulic oil discharged from the vane pump 101 flows and a return passage 35 that discharges the hydraulic oil to the tank 34, and surplus hydraulic oil that has flowed in from the vane pump 101 flows into the tank 34. A return port 33 that circulates is formed open.

  A through hole 37 constituting a part of the supply passage 12 is formed in the cap 28. The opening at one end of the through hole 37 communicates with the pump port 32, and the opening at the other end constitutes a supply port 29 that supplies all or part of the hydraulic oil flowing from the pump port 32 to the hydraulic device 10. The front end surface 38 of the cap 28 functions as a sheet surface with which the spool 30 abuts.

  The spool 30 is a substantially cylindrical member that is slidably inserted in the axial direction of the spool hole 31. The spool 30 and the spool hole 31 constitute a spool valve 21. The spool 30 can block communication between the pump port 32 and the return port 33 by sliding. In addition, the flow rate of the working fluid that returns from the pump port 32 to the return port 33 by the movement of the spool 30 can be adjusted. That is, the spool 30 can adjust the opening area between the pump port 32 and the return port 33.

  An upstream chamber 42 that communicates with the pump port 32 and into which hydraulic oil discharged from the vane pump 101 is guided is defined at the front end side of the spool 30. A spring chamber 39 is defined on the back side of the spool 30, and a spring 40 that urges the spool 30 toward the cap 28 is accommodated in the spring chamber 39.

  A tapered rod 41 is formed at the tip of the spool 30 and is inserted into the through hole 37 of the cap 28 and is expanded in diameter toward the tip. As the spool 30 moves, the taper rod 41 moves relative to the tip opening of the through hole 37, and the opening area of the through hole 37 changes. The variable diaphragm 20 is configured by the taper rod 41 and the through-hole 37 whose opening area changes as the taper rod 41 moves.

  The variable throttle 20 is provided facing the upstream chamber 42 and imparts resistance to the hydraulic oil flowing through the supply passage 12. A downstream chamber 44 defined on the downstream side of the variable throttle 20 communicates with the spring chamber 39 through the through hole 43. Thus, the pressure on the upstream side of the variable throttle 20 acts on one end of the spool 30 and the pressure on the downstream side of the variable throttle 20 acts on the other end. Accordingly, the spool 30 moves in accordance with the change in the differential pressure across the variable throttle 20, and balances the load based on the differential pressure across the variable throttle 20 and the biasing force of the spring 40 at a balanced position.

  When the flow rate of hydraulic oil discharged from the vane pump 101 is large and the differential pressure across the variable throttle 20 increases, the spool 30 moves in a direction to compress the spring 40 as shown in FIG. The return port 33 is opened. The arrow shown in FIG. 2 is the flow of hydraulic oil when the spool valve 21 is in the open state.

  When the spool 30 moves and the land portion 30 a opens the return port 33, the pump port 32 communicates with the return port 33 through the upstream chamber 42, and a part of the hydraulic oil discharged from the vane pump 101 returns to the return passage 35. To do. A passage that directly recirculates hydraulic oil from the upstream chamber 42 to the return passage 35 is a first recirculation passage 61. The flow rate of the hydraulic oil returning to the return passage 35 increases as the differential pressure across the variable throttle 20 increases, because the amount of movement of the spool 30 increases and the opening area of the return port 33 increases. That is, as the engine speed increases and the flow rate of hydraulic fluid discharged from the vane pump 101 increases, the flow rate increases.

  A conical groove 36 cut into a conical shape perpendicular to the axis of the spool hole 31 is formed on the wall surface of the spool hole 31 facing the return port 33. The conical groove 36 corresponds to a communication groove.

  The conical groove 36 is provided in order to balance the pressure in the direction perpendicular to the axis of the spool 30 and to suppress the flow rate by expanding the area through which the hydraulic oil flows. The conical groove 36 can communicate with the pump port 32 by sliding of the spool 30. Since the conical groove 36 is formed by inserting a drill from the return port 33 side, the apex is formed in a conical shape having a vertex of 120 degrees. The shape of the tip need not be a conical shape, and may be formed in a cylindrical shape with a flat tip.

  An annular recess 50 formed in an annular shape with a substantially rectangular cross section is provided on the back side of the land portion 30 a of the spool 30, and an annular oil chamber 55 is defined by the annular recess 50 and the inner periphery of the spool hole 31.

  The annular oil chamber 55 communicates with the return port 33 and the conical groove 36. When the spool valve 21 is opened, the working oil flows into the annular oil chamber 55 from the upstream chamber 42 through the conical groove 36. The hydraulic oil that has flowed into the annular oil chamber 55 flows through the annular oil chamber 55 to the return port 33. A passage for returning the working oil from the upstream chamber 42 to the return passage 35 through the conical groove 36 and the annular oil chamber 55 is a second return passage 62. The second reflux passage 62 corresponds to the reflux passage.

  As described above, the spool valve 21 returns a part of the hydraulic oil flowing from the pump port 32 to the return port 33 according to the differential pressure across the variable throttle 20. Since both the return port 33 and the conical groove 36 have a configuration in which the opening area changes as the spool 30 moves, the first return passage 61 and the second return passage 62 open and close in synchronization with the movement of the spool 30. On the back side of the annular oil chamber 55, that is, the side on which the hydraulic oil from the conical groove 36 collides, an annular groove 51 for accumulating air contained in the hydraulic oil as bubbles is formed.

  The annular groove 51 is an annular groove formed on the inner wall surface of the annular oil chamber 55 toward the back side of the spool 30. This annular groove 51 corresponds to a concave groove. The annular groove 51 is formed in the wall surface of the low-pressure side annular oil chamber 55 where hydraulic oil flows in from the high-pressure side conical groove 36 and collides when the spool valve 21 is in the open state. The annular groove 51 is formed so as to face the conical groove 36 across the annular oil chamber 55. By forming in this way, the impact when the hydraulic oil flowing from the conical groove 36 into the annular oil chamber 55 collides can be reduced.

  The annular groove 51 may be formed in a circular shape with a rectangular cross section as in the present embodiment, but may be formed in a circular shape with a semicircular cross section, or in a circular shape with a triangular cross section, that is, with a V-shaped groove. You may do it.

  Here, instead of the annular groove 51, the arc-shaped groove may be formed only in a portion where the hydraulic oil of the spool 30 collides. However, it is conceivable that the position where the spool 30 rotates around the shaft and the hydraulic oil collides with the position where the arc-shaped groove is provided due to an impact caused by the collision of the hydraulic oil. Therefore, when measures for suppressing the rotation of the spool 30 are not taken, it is desirable to provide the ring 30 like the annular groove 51.

  When the pressure on the downstream side of the variable throttle 20 reaches a predetermined value, the relief valve 22 is opened by compressing the spring 45 housed in the spool 30. When the relief valve 22 is opened, the hydraulic oil on the downstream side of the variable throttle 20 flows in the order of the downstream chamber 44, the through hole 43, the spring chamber 39, the relief valve 22, and the return port 33, and enters the return passage 35. Escaped.

  Hereinafter, operations of the variable throttle 20 and the spool valve 21 will be described.

  In the low speed range of the pump speed, the differential pressure across the variable throttle 20 is small, so the spool valve 21 is closed, and hydraulic oil proportional to the pump speed is supplied to the hydraulic device 10.

  When the pump speed reaches the middle speed range, the spool valve 21 is opened by the differential pressure across the variable throttle 20, and the pump port 32 and the return port 33 are communicated with each other by the first return passage 61 and the second return passage 62. A part of the hydraulic oil flowing into the upstream chamber 42 returns to the return passage 35 in accordance with an increase in the pump rotational speed. For this reason, the flow rate of the hydraulic oil supplied to the hydraulic device 10 through the variable throttle 20 is kept substantially constant.

  Here, since the hydraulic oil discharged from the vane pump 101 has a high pressure, there is a possibility that erosion may occur on the wall surface where the hydraulic oil collides when opened to the low pressure side. The erosion generated by the collision of the hydraulic oil that is recirculated from the first recirculation passage 61, that is, directly recirculated from the upstream chamber 42 to the return port 33 without passing through the annular oil chamber 55 occurs in the return port 33. The sliding operation of the spool 30 in the flow control valve 100 is not affected at all. However, when the oil is recirculated from the second recirculation passage 62, that is, when flowing into the annular oil chamber 55 from the conical groove 36, the spool is operated by the working oil recirculated from the conical groove 36 to the return port 33 through the annular oil chamber 55. When erosion occurs on the sliding surface between the hole 31 and the spool 30, the sliding surface is eroded. As the erosion progresses, the slidability of the spool 30 with respect to the spool hole 31 deteriorates, which may affect the flow characteristics of the flow control valve 100.

  By the way, a lot of gas such as air is dissolved in the hydraulic oil compressed to a high pressure. When the hydraulic oil flows from the upstream chamber 42 into the annular oil chamber 55 through the conical groove 36, the pressure of the hydraulic oil changes from high pressure to low pressure all at once. This is because the return port 33 communicates with the tank 34 that is at substantially atmospheric pressure.

  When the hydraulic oil flowing from the conical groove 36 into the annular oil chamber 55 changes from high pressure to low pressure, the gas dissolved in the hydraulic oil increases in volume as the pressure decreases and appears as bubbles. When the bubbles accumulate in the annular groove 51, they act as a cushioning material when the hydraulic oil collides. Therefore, the impact of the hydraulic oil from the conical groove 36 can be reduced and erosion can be prevented.

  When the pump speed reaches the high speed range, the differential pressure across the variable throttle 20 increases, so the spool 30 moves by compressing the spring 40. Thereby, the opening area of the opening part of the through-hole 37 is gradually reduced by the movement of the taper rod 41, and the flow rate of the hydraulic oil supplied to the hydraulic device 10 is gradually reduced.

  Further, when the vane pump 101 is stopped when the pump rotation speed becomes zero, the spool 30 is seated on the front end surface 38 of the cap 28 by the urging force of the spring 40. As a result, the variable throttle 20 is fully closed, the return port 33 is closed by the land portion 30a of the spool 30, and the spool valve 21 is also fully closed.

  As described above, in the present embodiment, the spool 30 is moved according to the differential pressure across the variable throttle 20, and the spool valve 21 is opened and closed. However, the spool 30 may be moved by the balance between the pressure of the working fluid flowing in from the pump port 32 and the biasing force of the spring 40 instead of depending on the differential pressure across the variable throttle 20.

  According to the above embodiment, the following effects are produced.

  In the second recirculation passage 62, the working oil flowing into the annular oil chamber 55 from the conical groove 36 collides with the wall surface of the annular oil chamber 55. At this time, when flowing out from the high pressure side conical groove 36 to the low pressure side annular oil chamber 55, the gas contained in the hydraulic oil appears as bubbles. The bubbles accumulate in an annular groove 51 that is recessed in the annular oil chamber 55, thereby acting as a cushioning material when the hydraulic oil collides with the wall surface of the annular oil chamber 55. Therefore, the impact of hydraulic oil at the time of collision is smaller than when hydraulic oil directly collides with the inside of the flow control valve 100. Therefore, even if the hydraulic oil discharged from the vane pump 101 is at a high pressure, erosion can be prevented from occurring inside, and the durability of the flow control valve 100 can be improved.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  The flow control valve of the fluid pressure pump according to the present invention can be used for hydraulic equipment such as a power steering device for a vehicle and a transmission.

It is the figure which showed the side surface of the flow control valve concerning embodiment of this invention in the cross section, and is a figure of a spool valve closed state. It is the figure which showed the side surface of the flow control valve by the cross section, and is a figure of the spool valve in an open state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Flow control valve 101 Vane pump 10 Hydraulic equipment 12 Supply path 20 Variable throttle 21 Spool valve 22 Relief valve 28 Cap 30 Spool 30a Land part 31 Spool hole 33 Return port 35 Return path 36 Conical groove 37 Through-hole 38 Front end surface 40 Spring 41 Tapered rod 42 upstream chamber 44 downstream chamber 50 annular oil chamber 51 annular groove

Claims (4)

A flow rate control valve that is interposed in a supply passage that guides the working fluid discharged from the fluid pressure pump to the fluid pressure device, and controls the flow rate of the working fluid supplied to the fluid pressure device;
A spool that moves according to the pressure of the working fluid discharged from the fluid pressure pump, and a part of the working fluid discharged from the fluid pressure pump is communicated to a suction side of the fluid pressure pump And a recirculating spool valve
A fluid pressure pump characterized in that a concave groove capable of storing gas contained in the working fluid as a bubble is provided on a wall surface of the spool on which the working fluid discharged from the fluid pressure pump and returning to the return passage collides. Flow control valve. The spool valve is
A spool hole formed in the valve body and into which the spool is slidably inserted;
An annular oil chamber formed in an annular shape on the outer periphery of the spool and in communication with the return passage;
A communication groove formed on the inner wall surface of the spool hole and capable of communicating the discharge side of the fluid pressure pump and the annular oil chamber by movement of the spool;
A reflux passage for returning working fluid from the discharge side to the return passage through the communication groove and the annular oil chamber,
The flow control valve of the fluid pressure pump according to claim 1, wherein the concave groove is formed on an inner wall surface of the annular oil chamber.   The flow rate control valve of the fluid pressure pump according to claim 2, wherein the concave groove is formed so as to face the communication groove with the annular oil chamber interposed therebetween. A variable throttle that is interposed in the supply passage and provides resistance to the working fluid;
The flow control valve of the fluid pressure pump according to any one of claims 1 to 3, wherein the spool moves according to a differential pressure across the variable throttle.

Images