JPH0321561A - Rate-of-flow control device for working fluid for power steering - Google Patents

Abstract

PURPOSE:To enhance the easiness in assembling by forming a valve hole in a spool valve fitted in a valve accommodation hole, forming a valve seat at an adaptor fixed to one end of this valve hole, seating thereon a valve seat member loosely fitted in the spool valve, and furnishing a ball valve at the other end of this valve seat member. CONSTITUTION:In a flow control device according to the present invention, a spool valve 17 is fitted in a valve accommodation hole 11 for adjusting the degree of opening of a communication path which puts a supply passage 14 leading to the discharge chamber of a pump in communication with a bypass passage 15 leading to the suction chamber of the pump. This spool valve 17 displaces in compliance with the pressures in front of and behind a throttle passage 25 provided in a union 12, which is screw fitted to one end of the mentioned valve accommodation hole 11. The spool valve 17 is provided with a valve hole 30 leading to No.2 valve chest 19, and passages 32-34 are formed at an adapter 31 screw fitted to one end of this valve hole 30, and within the spool valve 17, a valve seat member 36 equipped with a throttle hole 37 is loosely fitted slidably with possibility of seating itself on a valve seat 35 provided between the passages 33, 34. A ball valve 40 pressed by a spring 41 in the direction of closing is installed at No.2 valve seat 39 on the valve hole 30 side of this valve seat member 36.

Description

[Detailed description of the invention] Industrial application field> The present invention sends pressure oil discharged from a pump to a power steering device through a throttle passage, and recirculates surplus flow to the suction side through a bypass passage. This invention relates to a power steering working fluid flow rate control device. BACKGROUND TECHNOLOGY> This type of flow control device, as shown in FIG.
When the pressure in the second valve chamber 3a of the valve housing hole 3 exceeds a predetermined pressure, the ball valve 6 overcomes the spring 4 and separates from the valve seat 5, and the pressure in the second valve chamber 3a of the valve housing hole 3 increases. As a result, the spool valve 7 moves in the direction in which the opening degree of the bypass passage 8 becomes larger, and the first valve chamber 3 of the valve storage hole 3
This prevents the pressure at b from exceeding a predetermined pressure.

At low temperatures, the viscosity of the oil becomes high, and in particular, the resistance of the oil increases due to the filter 9 provided in the spool valve 7, causing a problem in that the relief pressure increases.

As a means to suppress the rise in relief pressure,
There is something like the one shown in Publication No. 7564, which is
The filter is installed inside the valve housing separately from the spool valve, and when the pressure in front of the filter increases, the filter overcomes the spring and moves, forming a passage for oil between the valve housing hole and the filter. It's resolved.

<Problems to be Solved by the Invention> In the above-mentioned device, since a communicating hole must be opened at the end of the valve housing hole, the wall thickness of the housing must be reduced to the extent that the communicating hole can be formed at the end of the valve housing hole. need to be formed. As a result, it is not possible to open only one end of the valve storage hole,
Since the spool valve can only be inserted from one side of the valve storage hole, there is a problem with ease of assembly. In addition, since the spring for the spool valve and the spring for the filter are the same, the relief pressure at which the filter moves and the differential pressure before and after the throttle passage when the spool valve moves can be set arbitrarily. There was a problem that I couldn't do it.

<Means for Solving the Problems> The present invention has been made in order to solve the above-mentioned problems of the conventional art. A radial hole is formed in the spool valve so that the valve hole and the bypass passage communicate with each other, and an adapter is attached to the rear end of the spool valve, and this adapter connects the second valve chamber of the valve storage hole and the valve. A first passage, a second passage having a larger diameter than the first passage, and a third passage having a smaller diameter than the second passage are continuously formed so as to communicate with the first passage. A first valve seat is formed between the second passages, and a valve seat member that abuts the first valve seat is loosely fitted into the second passage and the third passage so as to be movable in the axial direction of the spool valve. A throttle hole is formed in the valve seat member so that the first passage and the valve hole communicate with each other, and a second valve seat is formed on the valve hole side, and a throttle hole is formed in the valve seat member on the first passage side of the throttle hole. A filter is provided in the valve hole, a valve member that contacts the second valve seat is loosely fitted into the valve hole, and a second spring that biases the valve member in a direction that contacts the second valve seat is connected between the valve member and the valve. Insert the valve seat member between the holes and
A first spring biased in the direction of contacting the valve seat is inserted between the valve seat member and the valve hole.

<Function> With the above configuration, when the pressure in front of the filter exceeds a predetermined pressure at normal temperature, the valve member overcomes the second spring and moves, and the pressure oil in the second valve chamber of the valve housing hole flows to the bypass passage. The spool valve is released, and the spool valve moves in a direction in which the degree of opening of the bypass passage increases, thereby preventing the pressure oil in the first valve chamber of the valve housing hole from exceeding a predetermined pressure. When the viscosity of the oil increases at low temperatures and the pressure in front of the filter exceeds the set pressure of the first spring and second spring, the valve seat member overcomes the first spring and retreats, causing the valve housing hole to close. Pressure oil in the second valve chamber is released to the bypass passage through the second passage, the third passage and the radial hole, and the spool valve moves in the direction in which the opening degree of the bypass passage increases, and To prevent the pressure oil in one valve chamber from exceeding a predetermined pressure.

Example Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, reference numeral 10 indicates the main body of the pump. A valve housing hole II is formed in the pump body 10, a union 12 is screwed into one end of the valve housing hole l1, and a stopper l is attached to the other end.
3 is fitted. An outlet port 23 is opened in the union 12 and is connected to a servo valve of a power steering device. A supply passage 14 communicating with the discharge chamber of the pump and a bypass passage I5 communicating with the suction chamber of the pump are opened in the valve housing hole l1 and are spaced apart from each other in the axial direction.

Further, a flow rate adjustment spool valve l7 is slidably inserted into the valve storage hole 11 in order to close the communication passage between the supply passage 14 and the bypass passage 15 and to adjust the opening degree of the operation passage. A first valve chamber 18 and a second valve chamber l9 are formed on both sides of this spool valve 17. A spring 2 that presses the spool valve 17 toward the first valve chamber 18 is provided in the second valve chamber l9.
0 is provided, and the action of this spring 20 normally holds the spool valve l7 in a position where it collides with one end of the union 12, and blocks communication between the supply passage 14 opening into the first valve chamber 18 and the bypass passage 15. ing.

A throttle passage 25 is formed in the union l2, and the first valve chamber 18 and the outlet 23 communicate with each other via the throttle passage 25. A damping orifice 27 is opened between the throttle passage 25 and the outlet 23, and the damping orifice 27 communicates with the second valve chamber 19 through a communication hole 28 formed in the pump body 10. As a result, the pressure oil that has passed through the throttle passage 25 is guided to the second valve chamber 19, so that the pressure before and after passing through the throttle passage 25 act on both end surfaces of the spool valve 17. Therefore, the spool valve 17 is moved in the axial direction in response to the pressure drop in the throttle passage 25, and the opening degree of the bypass passage 15 is adjusted three times in order to keep the pressure drop in the throttle passage 25 at a constant value.

A valve hole 30 is bored in the spool valve 17 parallel to the axis of the spool valve 17, and an adapter 31 is screwed into one end of the valve hole 30. The adapter 31 has a first passage 3
2, a second passage 33 having a larger diameter than the first passage 32, and a third passage 34 having a smaller diameter than the second passage 33 are continuously formed. In between is the first
A valve seat 35 is formed. A valve seat member 36 that abuts the first valve seat 35 is loosely fitted into the second passage 33 and the third passage 34 so as to be movable in the axial direction of the spool valve 17, and the valve seat member 36 is fitted into the valve storage hole 11. A throttle hole 37 is formed in which the second valve chamber 19 and the valve hole 30 communicate with each other. A filter 38 is provided in front of the throttle hole 37 on the valve seat member 36.
A second valve seat 39 is formed on the valve hole 30 side. A ball valve 40 abuts on the second valve seat 39, and the ball valve 40 is biased in a direction to abut on the second valve seat 39 by a second spring 41 inserted between the valve holes 30. There is. A first spring 4 is provided between the valve seat member 36 and the valve hole 30 for biasing the valve seat member 36 in a direction to abut the first valve seat 35.
2 is inserted. valve? L30 is connected to the bypass passage 15 through a radial hole 43 formed in the spool valve l7.
are in constant communication.

In the above configuration, the working fluid is supplied from the pump to the supply port 8.
14, the first valve chamber 18, and the throttle passage 25 to the power steering device, a differential pressure is generated before and after the throttle passage 25.

This differential pressure acts on the spool valve 17, and the spool valve 17 adjusts the opening degree of the bypass passage 15 according to the flow rate of the working fluid supplied from the pump so that this differential pressure does not increase. The pressure after the throttle passage 25 is reduced by the damping orifice 27
is guided to the second valve chamber 19 through the communication hole 28, and when the pressure in the second valve chamber l9 reaches a predetermined pressure or higher at normal temperature, the ball valve 40 overcomes the second spring 41 and the second valve opens. It moves in the direction away from the seat 39, and the pressure oil in the second valve chamber 19 escapes to the bypass passage 15 through the throttle hole 37, the valve hole 30, and the radial hole 43. Due to the pressure drop in the second valve chamber 19, the spool valve 17 moves toward the stopper l3, increasing the degree of opening of the bypass passage 15 and preventing the pressure in the first valve chamber 18 from increasing.

At low temperatures, the viscosity of oil increases, so filter 38
is the resistance when oil flows. The filter 38 has a first
When the forces of the spring 42 and the second spring 41 act, and the pressure in the second valve chamber l9 of the valve storage hole 1l becomes higher than the pressure set by these springs 41 and 42, the valve seat member 36 moves against the spring 41. .42 and move. When the valve seat member 36 separates from the first valve seat 35, the oil in the second valve chamber 19 of the valve housing hole 11 escapes to the bypass passage 15 through the second passage 33, the third passage 34, and the valve hole 30. It will be done. Due to the pressure drop in the second valve chamber 19, the spool valve 17 moves toward the stopper l3, increasing the degree of opening of the bypass passage 15 and preventing the pressure in the first valve chamber l8 from increasing.

Therefore, it is possible to reduce the pressure loss of the pump due to an increase in the pressure of the pump at low temperatures.

Note that the relief pressure when the valve seat member 36 operates is set higher than the relief pressure when the ball valve 40 operates.

Effects of the Invention> As described above, the present invention provides a Subur valve with a valve hole formed in parallel with the spool valve, one end of which opens into the second valve chamber of the valve storage hole, and a bypass connection between the valve hole and the spool valve. A radial hole is formed that communicates with the passage, and an adapter is attached to the rear end of the Subur valve, and the second valve chamber of the valve storage hole and the first passage are connected to this adapter so that the second valve chamber of the valve storage hole and the A second passageway having a larger diameter than the passageway and a third passageway having a smaller diameter than the second passageway are continuously formed, and a first valve seat is formed between the first passageway and the second passageway. , a valve seat member that abuts the first valve seat is loosely fitted into the second passage and the third passage so as to be movable in the axial direction of the spool valve, and the valve seat member is fitted with the first passage and the valve hole. A second throttle hole is formed on the valve hole side.
a filter is provided on the valve seat member on the first passage side of the throttle hole, a valve member that comes into contact with the second valve seat is loosely fitted into the valve hole, and this valve member is attached to the second valve seat. A second spring biased in the direction of contacting the valve seat is inserted between the valve member and the valve hole,
Since the first spring that biases the valve seat member in the direction of contacting the first valve seat is inserted between the valve seat member and the valve hole, the communicating hole can be opened at right angles to the valve housing hole. I can do it. Therefore, both ends of the valve housing hole can be opened to the outside, and the spool valve can be selectively stored in the valve housing hole from both ends, thereby providing the advantage of improved assemblability. In addition, since the spring for the spool valve and the spring for the valve seat member can be used separately, the differential pressure before and after the throttle passage when the spool valve operates and the relief pressure at which the valve seat member operates can be adjusted independently. Can be set. Furthermore, since the first spring and the second spring of the valve member act on the valve seat member, a small first spring can be used, and the valve seat member and the first spring can be placed inside the spool valve. This allows the flow rate control device to be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a power steering working fluid flow rate control device showing an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional power steering working fluid flow rate control device. 11... Valve storage hole, 14... Supply passage, l5...
Bypass passage, l7... Spool valve, 25... Restriction passage, 30... Valve hole, 3l... Adapter, 32...
・First passage, 33...second passage, 34...third
passage, 35... first valve seat, 36... valve seat member,
38... Filter 39... Second valve seat, 40...
... Ball valve (valve member), 4l... Second spring, 42... First spring.

Claims (1)

[Claims] (1) A spool valve is slidably inserted into the valve storage hole to divide the valve storage hole into a first valve chamber and a second valve chamber, and the hydraulic pressure after the throttle passage is transferred to the second valve chamber of the valve storage hole through the communication hole. By guiding it to the valve chamber, the pressure before and after the throttle passage acts on the spool valve, and the pressure oil discharged from the pump is sent to the power steering device via the supply passage, the first valve chamber of the valve storage hole, and the throttle passage. In a power steering working fluid flow rate control device in which surplus flow is returned to the suction side of the pump through a bypass passage whose opening degree is adjusted by a spool valve, one end of the spool valve is connected to a valve storage hole. A valve hole opening into the second valve chamber is formed in parallel with the spool valve, and a radial hole is formed in the spool valve through which the valve hole and the bypass passage communicate with each other, an adapter is attached to the rear end of the spool valve, and the adapter is attached to the rear end of the spool valve. A first passage, a second passage having a larger diameter than the first passage, and a third passage having a smaller diameter than the second passage so that the second valve chamber of the valve storage hole and the valve hole communicate with each other. A first valve seat is formed between the first passage and the second passage, and a valve seat member that abuts the first valve seat is connected to the second passage and the third passage. It fits loosely in the spool valve so as to be movable in the axial direction, and a throttle hole is formed in the valve seat member through which the first passage and the valve hole communicate with each other, and a second passage is formed on the valve hole side.
a filter is provided on the valve seat member on the first passage side of the throttle hole, a valve member that comes into contact with the second valve seat is loosely fitted into the valve hole, and this valve member is attached to the second valve seat. A second spring biased in the direction of contacting the valve seat is inserted between the valve member and the valve hole,
A flow rate control device for a working fluid for power steering, characterized in that a first spring biasing the valve seat member in a direction to abut the first valve seat is inserted between the valve seat member and the valve hole.