JPH0729268Y2 - Flow control valve - Google Patents

Description

The present invention relates to a flow control valve attached to a liquid pump driven by an engine of an automobile.

2. Description of the Related Art As shown in FIG. 5, a liquid pump for supplying hydraulic oil to a power steering device of a vehicle is provided with a flow control valve 40 on its discharge side. The flow rate control valve 40 supplies the entire amount of hydraulic oil that has flowed into the spool chamber 42 from the discharge side flow path 41 of the pump to the supply port 43 when the discharge amount of the pump is less than or equal to a predetermined amount.
Is supplied to the power steering (not shown) via. When the discharge amount of the pump becomes larger than a predetermined amount, the flow control valve 40 moves the spool 44 from the position A to the position A ′ in the drawing to open the drain flow passage 45, thereby opening the excess oil to the drain flow passage.
It is returned to the pump chamber and the oil storage tank again via 45, and only a predetermined amount of hydraulic oil is supplied to the power steering device (for example, see Japanese Utility Model Laid-Open No. 59-21173).

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the conventional flow rate control valve, the cross-sectional shape of the drain passage 45 is formed in a substantially circular shape. In addition, the direction of the flow of oil flowing from the spool chamber 42 to the drain passage 45 is sharply bent. Therefore, in the oil flow in the vicinity of the spool chamber side opening of the drain passage 45, the length of the streamline from the opening to the inner wall of the drain passage 45 where the flow collides is different between the central portion and the peripheral portion of the opening end. It will collide with the inner wall of the drain passage 45 significantly differently. Therefore, in the drain passage 45, the flow becomes a complicated flow accompanied by a two-dimensional flow. Therefore, cavitation may occur in the drain passage 45, which may cause problems such as generation of abnormal noise and erosion of the drain passage.

Therefore, the present invention aims to solve the problems of the conventional example.

Means for Solving the Problem That is, according to the present invention, a pump discharge side flow passage and a drain flow passage are formed in the peripheral wall of a spool chamber by axially displacing both of them.
A flow rate control valve in which the opening area of the drain passage is adjusted by a spool housed in the spool chamber so that excess of the fluid introduced into the spool chamber from the pump discharge side passage is discharged to the drain passage. In, the cross-sectional shape of at least the opening on the spool chamber side of the drain flow path to a portion in the vicinity thereof in a direction orthogonal to the longitudinal direction of the drain flow path, the curvature radius of the inner wall in the initial opening is It is characterized in that it is formed to be smaller than the radius of curvature of the inner wall in.

Operation As a result of the present invention having the above-mentioned characteristic configuration, the flow velocity distribution on the flow passage cross section near the spool chamber side opening of the drain flow passage is made uniform and the flow is rectified, so that the occurrence of cavitation is suppressed.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a liquid pump using a flow control valve of the present invention together. In the figure, reference numeral 1 denotes a casing, and a cam ring 3 forming a pump chamber 2 is accommodated in the casing 1. A rotor 4 having a plurality of vanes is rotatably accommodated in the cam ring 3, and the opening of the rotor 4 is covered with a lid 5.
It is blocked by. Reference numeral 6 is a rotating shaft engaged with the rotor 4. The rotary shaft 6 has a cover 5 at one end through a bearing 7.
Is rotatably supported, and the other end is rotatably supported by the casing 1 via a bearing 8. The axial positioning of the rotary shaft 6 and the bearing 8 is performed by a C-shaped retaining ring 9 fitted to the rotary shaft 6. As a result, the shaft portion 6a with which the oil seal 10 is in sliding contact and the shaft portion 6b with which the bearing 8 is engaged can have the same diameter, which facilitates the polishing of the rotary shaft 6 and the assembly of the oil seal 10. Seal lip 10 at the time
Care is taken to prevent damage to a. The rotary shaft 6 has a pulley 11 fixed to its shaft end and is connected to an engine (not shown) via a winding transmission mechanism. Therefore,
The rotating shaft 6 rotates the rotor 4 by the driving force of the engine. As a result, the hydraulic oil introduced into the pump chamber 2 from the suction flow passage 12 is pressurized in the pump chamber 2 and then discharged to the discharge side flow passage 13. Then, the amount of oil supplied to the power steering (not shown) is adjusted by the flow rate control valve 14 arranged in the discharge side flow path 13.

FIG. 2 is a sectional view of the flow control valve 14.

The flow rate control valve 14 accommodates a spool 16 in a spool chamber 15 that communicates with the discharge side flow path 13 so as to be capable of reciprocating. The spool 16 defines the inside of the spool chamber 15 into a front chamber 15a and a rear chamber 15b. Of these, oil discharged from a pump chamber (not shown) is introduced into the front chamber 15a through the discharge-side flow path 13. On the other hand, the hydraulic pressure on the actuator side of a power steering device (not shown) is introduced into the back chamber 15b via a pressure sensitive orifice 17 formed in the spool 16. The front chamber 15a communicates with a power steering device (not shown) via the supply port 19 of the plug 18 fitted to the open end of the front chamber 15a. On the other hand, the back chamber 15b is
When the internal pressure increases, the relief valve 20 built into the spool 16 and the relief channel 21 formed in the spool 16 communicate with the drain channel 22. The drain passage 22 communicates with the pump chamber 2 via the suction passage 12 as shown in FIG.

In the flow rate control valve 14 configured as described above, the rotational speed of the pump (the rotational speed of the engine) increases and the pressure difference between the front chamber 15a side and the back chamber 15b side increases, and the spool 16 pushes the valve spring 23. Shrink and move to the right in the figure. Here, when the rotation speed of the pump is equal to or lower than the predetermined rotation speed (low speed rotation), the drain passage 22 and the front chamber 15a are blocked by the spool 16, and the entire amount of oil discharged from the pump is supplied via the supply port 19. Is supplied to the power steering device. On the other hand, when the rotation speed of the pump is equal to or higher than the predetermined rotation speed (high speed rotation), the spool 16 connects the drain passage 22 and the front chamber 15a, and a part of the discharged oil is supplied through the supply port 19 to the outside of the drawing. While supplying the power to the power steering device, the excess discharge oil is returned to the pump chamber 2 through the drain passage 22 to control the supply amount to the power steering device.

FIG. 3 shows a sectional shape of the drain channel 22.

In general, the drain passage 22 is formed so as to be axially displaced with respect to the spool chamber side opening 13a of the discharge side passage 13. Therefore, the excess discharge oil, when flowing out from the front chamber 15a to the drain passage 22, can be bent sharply, so that the velocity of the outer flow having a small curvature is greater than the velocity of the inner flow having a large curvature. Also grows. However, the drain passage 22 has a sectional shape in a direction orthogonal to the longitudinal direction of the drain passage from the opening portion to the portion in the vicinity of the opening portion, and the radius of curvature of the inner wall 46 at the initial opening portion is the inner wall at the target position. It is formed to be smaller than the radius of curvature of 47. In the case of this embodiment, the radius of curvature of the inner wall 47 at the target position is set to be almost infinite. As a result, the flow velocity distribution of oil near the spool chamber side opening of the drain passage 22 is made uniform on the passage cross section and rectified. Therefore, cavitation in the drain passage 22 can be prevented, and abnormal noise caused by cavitation and erosion of the wall surface of the drain passage 22 can be prevented. In addition, the metal powder generated by the erosion of the wall surface of the drain passage 22 does not cause abnormal wear on the sliding parts of the pump.

FIG. 4 is a detailed view of the relief valve 20 built in the spool 16.

The relief valve 20 shown in this figure includes a valve seat portion 24, a valve body portion 25, and a relief spring 26. The valve seat portion 24 is
A valve hole 28 and a valve seat surface 29 are formed in the plug 27, and the valve hole 28
A filter 30 is attached to the end portion on the side of the back chamber to prevent the occurrence of problems such as clogging of the valve hole 28. Filter 30
An annular portion 31 made of a non-metallic elastic member such as rubber or resin is formed on the outer periphery of the annular portion 31, and the annular portion 31 is fitted into a mounting groove 32 formed in a plug 27 to be mounted. Therefore,
When attaching the filter 30 to the plug 27, it is not necessary to caulkly fix the filter 30 and the plug 27. Also, plug 27
Is to be inserted into the hollow hole 33 of the spool 16 by press fitting, but since there is no large-diameter stepped portion such as a collar portion on the outer periphery of the spool 16, the press-fitting amount can be adjusted arbitrarily, which allows the relief spring to be adjusted. Initial set load of 26 (relief pressure)
Can be adjusted. The plug 27 may be screwed and fixed in the hollow hole 33.

In the relief valve 20 having such a configuration, when the pressure in the back chamber 15b becomes equal to or higher than the predetermined pressure, the valve body portion 25 including the spherical body 25a and the retainer 25b moves to the left side in the figure against the spring force of the relief spring 26. And open the valve. Therefore, the oil in the back chamber 15b flows out to the drain passage 22 through the hollow hole 33 and the relief passage 21.

Effect of the Invention As described above, according to the present invention, the cross-sectional shape of at least the opening of the drain passage on the spool chamber side to its vicinity is defined by the cross-sectional shape in the direction orthogonal to the longitudinal direction of the drain passage on the inner wall of the initial opening. The radius of curvature of the drain is smaller than that of the inner wall at the target position, and the flow velocity distribution on the cross section of the drain passage near the spool chamber side opening is made uniform and the flow is rectified. To do. As a result, it is possible to prevent the occurrence of cavitation in the drain channel, and to provide a quiet and durable liquid pump.

[Brief description of drawings]

FIG. 1 is a sectional view of a liquid pump to which the flow control valve of the present invention is applied, FIG. 2 is a sectional view of a flow control valve showing an embodiment of the present invention, and FIG. 3 is a line II-II of FIG. FIG. 4 is an enlarged sectional view of the relief valve, and FIG. 5 is a sectional view of essential parts of a conventional flow control valve. 2 ... Pump chamber, 13 ... Discharge side passage, 14 ... Flow control valve, 15 ... Spool chamber, 16 ... Spool chamber, 22 ... Drain passage.

Claims (1)

[Scope of utility model registration request] 1. A pump discharge side flow path and a drain flow path are formed on a peripheral wall of a spool chamber by axially displacing them, and an opening area of the drain flow path is adjusted by a spool housed in the spool chamber. In a flow control valve configured to allow an excess of the fluid introduced into the spool chamber from the pump discharge side flow passage to flow out to the drain flow passage, in at least the spool chamber side opening of the drain flow passage and its vicinity. The cross-sectional shape up to the portion in the direction orthogonal to the longitudinal direction of the drain passage is characterized in that the radius of curvature of the inner wall at the initial opening is smaller than that and the radius of curvature of the inner wall at the target position. Flow control valve to.