JPH0754055Y2 - Flow control valve - Google Patents

Description

TECHNICAL FIELD The present invention relates to a flow control valve of a liquid pump used in a power steering device of an automobile or the like.

2. Description of the Related Art Conventionally, when a pump discharge pressure exceeds a predetermined pressure, a flow control valve of this type allows a part of the discharge amount to escape to the pump suction side and adjusts the amount of liquid supplied from a liquid pump to another device. It is like this.

And, as a flow control valve for such a liquid pump,
The ones disclosed in FIGS. 5 to 5 are known. this is,
A spool valve that functions as a flow control valve on the pump discharge side A
30 is provided, and a supply port 32 that opens in the axial direction is formed at the axial end position of the spool chamber 31 of the spool valve 30 while the spool chamber 31 and the port suction port are formed in the side wall 33 of the spool chamber 31. The drain port 34 communicating with the side B is formed as an opening, and the opening area of the drain port 34 is adjusted according to the pump discharge pressure by the spool 35 housed in the spool chamber 31, and the drain port 34 is connected to another device via the supply port 32. The amount of liquid supplied is adjusted (see, for example, Japanese Utility Model Laid-Open No. 60-70791).

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a conventional example, when the pump rotation speed is equal to or higher than a predetermined rotation speed and the pump discharge pressure is equal to or higher than a predetermined pressure, the spool 35 has a drain port 34 Even if the opening area is increased, the amount of liquid supplied to another device through the supply port 32 shows a gradual increase tendency as shown by the T ₀ line in FIG. Therefore, the pump speed becomes higher than the predetermined speed,
When the pump discharge pressure is equal to or higher than a predetermined pressure, it is difficult to adjust the liquid flow rate as desired even if the liquid supplied to another device is desired to be constant or gradually reduced.

Means for Solving the Problems According to the present invention, a discharge port into which a liquid discharged from a pump flows and a drain port from which a surplus amount of the liquid discharged from the discharge port is discharged are formed in a side wall of a spool chamber. On the other hand, at the axial end of the spool chamber, a supply port for supplying the liquid that has flowed in from the discharge port to the hydraulic device is disposed, and in the spool chamber, the opening area of the drain port is adjusted, In a flow control valve that accommodates a spool that adjusts the amount of liquid that flows out through the supply port, the supply port is biased from the axial center of the spool chamber toward the drain port, and is located between the discharge port and the drain port. The feature is that an opening is formed.

Operation As a result of the present invention having the above-mentioned characteristic structure, when the hydraulic pressure on the hydraulic pressure generating side, for example, the pump discharge pressure becomes equal to or higher than a predetermined pressure, the spool moves in the axial direction, and the drain port opens into the spool chamber and the discharge port. A part of the liquid that has flowed into the spool chamber from returns to the pump suction side through the drain port. At this time, since the supply port is located between the discharge port and the drain port and has an opening, the flow of the liquid flowing out from the spool chamber through the supply port is limited by the flow velocity of the liquid flowing from the discharge port to the drain port. to be influenced. Therefore, the amount of liquid flowing out from the supply port is constant or gradually reduced regardless of the increase in the hydraulic pressure on the hydraulic pressure generating side.

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

FIG. 1 is a cross-sectional view of a liquid pump, in which FIG.
Is the pump body. A working chamber 2 is formed in the pump body 1, and a plurality of vanes 3 are provided in the working chamber 2.
And a rotary shaft 5 for rotating the same. The rotating shaft 5 is pivotally supported in a mounting hole 7 of the pump body 1 by a bearing 6. Then, by rotating the rotating shaft 5 by a drive source such as an engine (not shown), the liquid introduced from the suction port 8 into the working chamber 2 is pressurized by the rotor 4 and the vanes 3 and the like, and discharged from the discharge port 9. It is supposed to do. Reference numeral 10 is a flow rate control valve disposed on the pump discharge side A, the details of which are shown in FIG. The flow rate control valve 10 includes a spool 12 that is reciprocally housed in a spool chamber 11 formed in the pump body 1, and a spring 13 that biases the spool 12 in one direction. A drain port 15 is formed on the side wall 14 of the spool chamber 11 so as to communicate the inside of the spool chamber 11 with the pump suction side B. The opening area of the drain port 15 is adjusted by the spool 12 that responds to the pump discharge pressure. Reference numeral 16 denotes a connector, which is fitted to the axial end of the spool chamber 11 and fixed by a pin 17.
The connector 16 is provided with a supply port with a predetermined amount of deviation from the axial center position of the spool chamber 11 toward the drain port 15 side.
An opening 18 is formed, and the supply port 18 is located between the discharge port 9 and the drain port 15. The supply port 18 of the connector 16 opens in the axial direction of the spool chamber 11 and connects the spool chamber 11 and a device (not shown).

The spool 12 has a relief valve that allows liquid to escape to the drain port 15 (pump suction side B) through the relief flow passage 19 when the bottom 11a side of the spool chamber 11 has an abnormally high pressure.
Built-in 20.

According to the above-described structure of the embodiment, the rotation speed of the pump (the rotation shaft 5
The pump discharge pressure does not rise to such a degree that the spring 13 for urging the spool 12 is sufficiently compressed until the rotational speed) reaches a predetermined rotational speed. Therefore, drain port 15 is spool 12
Is blocked by. In this state,
As indicated by the T _1a line, the amount of liquid flowing out via the supply port 18 increases in proportion to the increase in the pump rotation speed.

When the pump rotation speed reaches a predetermined rotation speed, the pump discharge pressure acting on the pressure receiving surface 12a of the spool 12 through the discharge port 9 is sufficiently increased. Therefore, the spool 12 moves in the axial direction (upward in FIG. 2) by pressing and contracting the spring 13, and opens the drain port 15 in the spool chamber 11. As a result, a part of the pump discharge amount is returned to the pump suction side B through the drain port 15, and the remaining pump discharge amount flows out from the supply port 18. At this time, the liquid flowing out from the supply port 18 has the opening of the supply port 18 biased toward the drain port 15 side and the supply port 9 and the drain port.
Since it is located between the discharge ports 9, it is affected by the flow velocity of the fluid flowing from the discharge port 9 into the opening 21 formed by the drain port 15 and the spool 12, and the flow rate of the fluid changes regardless of the increase in the pump rotation speed. It becomes almost constant (see T _1b line in FIG. 3).

Stop the rotation of the pump (stop the rotating shaft 5), and
When the pressure in 11 drops sufficiently, the spool 12 will
Spring until 12a abuts end 18a of supply port 18.
It is urged at 13 and moves. Therefore, the drain port 15 is closed by the spool 12.

Depending on the amount of deviation of the opening position of the supply port 18, the third
It has been confirmed by experiments that the amount of liquid flowing out from the supply port 18 can be gradually reduced as the pump speed increases, as indicated by the T ₂ line in the figure.

Effect of the Invention As described above, according to the present invention, the supply port is biased from the axial center of the spool chamber to the drain port side and is positioned between the discharge port and the drain port to form an opening, so that it flows out through the supply port. The flow rate of the liquid can be influenced by the flow velocity of the liquid flowing from the discharge port to the drain port, and the amount of the liquid flowing out from the supply port can be constant or gradually reduced regardless of the increase in the hydraulic pressure on the hydraulic pressure generating side. it can.

[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 taken along line II-II of FIG. 1, FIG. 3 is a flow rate characteristic diagram, and FIG. 4 is conventional. FIG. 5 is a sectional view of a liquid pump showing an example, and FIG. 5 is a sectional view taken along the line III-III in FIG. 10 ... Flow control valve, 11 ... Spool chamber, 12 ... Spool, 14 ... Side wall, 18 ... Supply port, A ... Pump discharge side, B ... Pump suction side.

Claims (1)

[Scope of utility model registration request] 1. A spool chamber is provided with a discharge port into which a liquid discharged from a pump flows, and a drain port from which a surplus liquid discharged from the discharge port is discharged. A supply port that supplies the liquid that has flowed in from the discharge port to the hydraulic device is provided at the axial end of the, and the opening area of the drain port is adjusted in the spool chamber and flows out through the supply port. In a flow rate control valve that accommodates a spool that adjusts the amount of liquid to be discharged, the supply port is biased from the axial center of the spool chamber to the drain port side, and is formed between the discharge port and the drain port to form an opening. And flow control valve.