JPH01132471A - Flow control valve - Google Patents

Abstract

PURPOSE:To simplify the construction and offer the arbitrary flow control characteristics by giving the pressure loss preventing function to a valve which has the flow drop characteristics, that is, executes the drooping function. CONSTITUTION:When the revolution speed of a pump 6 driven by an automobile engine is increased gradually, a spool valve 3 is moved to the right due to pressure difference between the front and the rear position of each of a fixed orifice 4c and other orifices 4d and 4e. When a flow return passage 7 is communicated with a supply passage 5, excess of flow is returned so that the quantity of fluid fed to a power steering device P.S is kept constant. A sleeve 12 is moved to the left due to the pressure difference between the front and the rear position of a limited flow passage 16. As a result, the sleeve 12 has each of the orifices 4d and 4e reduce in bore so that the pressure difference between the front and the rear position of each of the orifices 4c-4e is increased, on account of which the spool valve 3 is moved to the right to increase the quantity of return flow. The quantity of oil fed to the power steering device P.S may be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flow rate control valve, and particularly relates to a flow rate control valve that controls the flow rate drooping characteristic (drooping), that is, the flow rate supplied to hydraulic equipment as the pump discharge rate increases. The present invention relates to a flow control valve having a so-called non-return drooping characteristic, in which the supply flow rate is prevented from returning due to pressure fluctuations in hydraulic equipment.

(Prior Art) Flow control valves having the above-mentioned characteristics are generally used in vehicle power steering devices and are useful for vehicle stability during high-speed driving, reduction of horsepower consumption, etc. As this type of device, For example, an orifice is provided in a supply passage that supplies pressurized fluid discharged from a pump to hydraulic equipment, and the differential pressure before and after the orifice opens a spool valve to allow some of the pressure fluid to flow back. A restriction passage is provided in the pump, and the orifice is reduced by a control spool that responds to the pressure difference before and after the restriction passage.Furthermore, since the pressure difference before and after the restriction passage acts as a pressure loss inside the pump, A device equipped with a relief valve to prevent the differential pressure from rising more than necessary is already known (Japanese Unexamined Patent Publication No. 57
-4470 Publication).

(Problems to be Solved by the Invention) However, all of the flow control valves with the above configurations have a complicated structure and a large number of parts, requiring manufacturing precision, and it is also difficult to tune the characteristics. Met.

The present invention has been made in view of the above drawbacks, and provides a flow control valve that can obtain drooping characteristics with an extremely simple configuration and that can regulate the pressure difference before and after the restriction passage from increasing more than necessary. This is what we provide.

[Means for Solving the Problems] The flow control valve according to the present invention has an orifice in the supply passage that supplies the pressure fluid discharged from the pump to the hydraulic equipment, and opens the spool valve by the differential pressure before and after the orifice. A part of the valve valve pressure fluid is recirculated, and a cylindrical union fitted to the shaft core of the connector is inserted into the spool valve storage hole formed in the pump housing and fixed to the housing. The orifice is formed in the union, and an annular space is formed between the connector and the union, a sleeve is slidably fitted into this space, and the sleeve is formed between the union and the hole in the housing. The orifice is controlled to shrink by sliding the sleeve based on the pressure difference before and after the restriction passage, and the union is provided with a passage hole that communicates the upstream side and the downstream side of the restriction passage when the sleeve moves by a predetermined amount or more. It is characterized by the fact that it has been formed.

(Function) In the flow control valve according to the present invention, the orifice is controlled to be reduced by moving the sleeve based on the pressure difference before and after the restriction passage,
Furthermore, when the pressure difference increases, the passage hole is opened to reduce the flow rate passing through the restriction passage, thereby preventing an increase in pressure loss.

〔Example〕

The present invention will be explained below with reference to illustrated embodiments. The figure shows a flow control valve according to an embodiment of the present invention, in which a spool valve housing hole (2) with a large diameter on the opening side is formed in the pump housing (1), and the hole (2) has a large diameter on the opening side. Small diameter part (2a)
A spool valve (3) is housed inside, and a cylindrical union (4) with one end press-fitted into a hole (10a) in the shaft core of the connector (10) is inserted into the large diameter part (2b). The union (4) is fixed in the valve housing hole (2) by screwing the connector (10) to the housing (1). The large diameter part (2b) of the valve housing hole (2) is connected to the supply path (
5) to the pump (6), and the small diameter part (2a) to the tank (8) via the reflux path (7), and the spool valve (3) in the small diameter part (2a) The union (4) is urged toward the large diameter portion (2b) by the spring (9) and stops when it hits the protrusion (4a) formed on the tip surface of the union (4), thereby establishing communication between the supply path (5) and the return path (7). It's blocked.

A flange (4b) whose outer periphery is bent toward the spool valve (3) is formed around the part of the end of the cylindrical union (4) where the protrusion (4a) is formed. 4b) Gap between outer surface and valve storage hole (2) inner surface (16)
constitutes a restriction passage that restricts the flow rate of pressure oil supplied from the oil pump (6).

A recess (10b) is formed in the inner peripheral surface of the connector (10), and the inside of this recess (10b), that is, the connector (
10) Annular space (1) between the inner surface and the outer surface of the union (4)
1), a sleeve (12) is slidably fitted into the flange (1) of the union (4) by means of a spring (13).
4b) side. A protrusion (12a) is provided on the end surface of the flange (4b) of the sleeve (work 2), and this protrusion (12a) connects the sleeve (12) and the flange (4b).
4b), a gap (14) is formed between the two.

A fixed orifice (4c) is formed inside the center of the cylindrical union (4). A union (
4) Two metering orifices (
4d) and (4e) are provided at different axial positions. Both of these orifices (4d).

(4e) is opened when the sleeve (12) is stopped against the flange (4b), and is sequentially closed when the sleeve (12) moves as will be described in detail later. Also, fixed orifice (4c)
A radial passage (4f) communicating between the inside and outside of the union (4) is formed on the exit side of the union (4). In addition, the union (
Attach the union (4) to the part near the flange (4b) of 4).
A plurality of passage holes (4g) are provided that allow communication between the inside and the outside. These passage holes (4g) are formed in positions where they are closed when the sleeve (12) is at rest, as shown, and opened when the sleeve (12) moves a predetermined amount.

Therefore, the supply path (5) from the pump is connected to the connector (1
0), a chamber (15) around the valve storage hole (2) a gap (limited passage) between the inner surface and the outer surface of the flange (4b) (16), a chamber between the flange (4b) and the spool valve (3) ( 17
), the internal passage (4h) of the union (4), the fixed orifice (4c), and the passage (1) in the shaft center of the connector (10).
It is connected to the power steering device (p, s,) via 0c), etc. In addition, the internal passage (4h) of the union (4) is
An annular space (11) containing a spring (13) pressing against the sleeve (12) by metering orifices (4d), (4e) and a radial passage (4f)
Further, this annular space (11) is connected to the inside of the housing (1) via a radial passage (10d) of the connector (10), an annular groove (10e) on the outer circumferential surface, a passage (1a) in the housing (1), etc. The spring that biases the spool valve (3) (
9) is connected to the chamber (18) containing the. Therefore,
When the flow rate of the pressure oil discharged from the pump (6) exceeds a certain value, the differential pressure across the fixed orifice (4C) and metering orifice (4d) and (4e) acts on both end faces of the spool valve (3). When the spring (9) is overcome, the spool valve (3) is moved to the right in the figure, and a portion of the pressure oil supplied from the pump (6) is transferred to the tank (8).
) and also the pressure and restriction passage (16) in the supply passage (5) and each orifice (4c).

When the difference between the pressure in the annular space (11) on the downstream side of (4d) and (4e) exceeds a predetermined value, the sleeve (1
2) is designed to slide.

To explain the operation of the flow control valve configured as above, in the low speed rotation range (low flow range) of the pump (6) driven by the vehicle engine, the spool valve (3) is controlled by the force of the spring (9). The protrusion (4a) of the union (4)
) to block the supply path (5) and the return path (7), and the sleeve (12) is also stopped by a spring (13) against the back surface of the flange (4b) of the union (4). Therefore, the entire amount of pressure oil discharged from the pump (6) is supplied to the power steering device (p, s,).

Next, as the pump rotation speed gradually increases, the discharge flow rate increases and the fixed orifice (4c) and orifice (4c
l), (4e) The spool valve (3) begins to move to the right due to the differential pressure between the front and rear, and when the recirculation passage (7) communicates with the supply passage (5) side, the surplus flow is recirculated and the power steering device (p ,s
,) is kept approximately constant.

Furthermore, as the pump rotation speed increases, the restricted passage (
16) The pressure difference between the front and rear becomes large, and this force overcomes the biasing force of the spring (13), causing the sleeve (12) to move to the left. As a result, the sleeve (12) first starts squeezing the first orifice (4d) and then the second orifice (4d).
Gradually narrow down the orifices (4c) and (4).
d), (4e) The pressure difference before and after increases, causing the spool valve (3) to move further to the right and increasing the recirculation amount. By reducing the amount of oil supplied to the power steering system (p, s,) in this way, the high-speed stability of the vehicle is improved, and
It is possible to reduce horsepower consumption during high-speed running.

When the pump rotation speed further increases and the discharge flow rate from the pump (6) shows a further increase, the sleeve (12)
) moves further to the left and opens the passage hole (4g). As a result, a chamber (
15) A part of the pressure oil that has entered inside enters the internal passage (4h) of the union (4) through the passage hole (4g), so the amount of oil passing through the restriction passage (16) decreases, resulting in pressure loss. can suppress the increase in

As described above, according to this embodiment, it is possible to obtain drooping characteristics with a simple configuration, and the restriction passage (16)
After the sleeve (12) moves due to the pressure difference between the front and rear and contracts the orifices (4c), (4d), and (4e), the amount of oil passing through this passage (16) is reduced to prevent further pressure. It is possible to suppress an increase in the difference and prevent an increase in pressure loss.

Note that the shape of the flange (4b) of the union (4), the position, shape, number, etc. of the orifices (4c), (4d), (4e) and passage holes (4g) are not limited to the above embodiments. .

〔Effect of the invention〕

As described above, according to the present invention, a valve that performs a drooping action can be provided with a pressure loss prevention function, thereby simplifying the structure of the flow control valve, reducing the number of parts, and lowering costs. Additionally, arbitrary characteristics can be obtained by replacing only the connector assembly including the union, sleeve, etc.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a longitudinal sectional view of a flow control valve according to an embodiment of the present invention. (1) Pump housing, (2) Spool valve storage hole, (3) Spool valve, (4) Union, (4c), (4d), (4e) ”- Orifice, (4g)...passage hole, (6)...pump, (10)...connector, (11)...annular space, (12)...sleeve, (16)... Restricted passage, (p, s,)...Hydraulic equipment.

Claims (1)

[Claims] In the flow control valve, an orifice is provided in the supply passage that supplies pressurized fluid discharged from the pump to the hydraulic equipment, and the spool valve is opened by the differential pressure before and after the orifice, and a part of the pressure fluid is returned to the pump housing. A cylindrical union fitted to the shaft core of the connector is inserted into the formed spool valve storage hole and fixed to the housing, and the orifice is formed in this union, and a gap is formed between the connector and the union. An annular space is formed in the space, and a sleeve is slidably fitted into this space, and the orifice is compressed by sliding the sleeve due to the pressure difference before and after the restriction passage formed between the union and the hole in the housing. What is claimed is: 1. A flow rate control valve that is controlled by a small amount and has a passage hole in the union that communicates between the upstream side and the downstream side of the restriction passage when the sleeve moves by a predetermined amount or more.