JPH01293276A - Linear solenoid valve - Google Patents

Abstract

PURPOSE:To prevent the sudden shift of a spool in an open direction and stabilize a flow rate by improving the shape of a slit formed at the spool end of a linear solenoid value. CONSTITUTION:A center hole 23 is opened through the center of a spool 20 and one end of the spool 20 is cut out radially for the formation of a bypassing slit 21. This slit 21 is continuous to the center hole 23. A counter bore groove 38 is formed at the cutout edge 21a of the slit 21, and this edge 21a is formed to have a sharp angle. Furthermore, an annular end plate 40 is fitted to cover the open end of the slit 21 of the spool 20. A gap 50 is formed around the external surface of the end plate 40 to constitute an orifice with the internal surface of a value proper 10. Further, the edge of the plate 40 is engraved with a throttle hole 41 orthogonal with the slit 21, and a relief groove 60 is formed on the internal surface of the valve proper 10 at a position corresponding to the slit 21 on a circumference.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a linear solenoid valve that linearly controls pressure fluid flowing from a high-pressure side flow path to a low-pressure side flow path in accordance with a control current applied to a solenoid. It is something.

<Prior art> In a vehicle speed-sensitive power steering device that linearly controls steering force according to vehicle speed, pressure fluid flows from a high-pressure side flow path to a low-pressure side flow path in response to a control current applied to a solenoid. A linear solenoid valve is used to linearly control the

Conventionally, as shown in FIG. 3, this type of linear solenoid valve has a first and second flow path P provided in a power cylinder 32 through which high pressure fluid and low pressure fluid selectively flow.
1, has two ports 12.13 each communicating with P2, and has an inner hole 1 into which these two ports 12.13 open.
1, and a cylindrical spool that is slidably fitted into the inner hole 11 and has a bypass slit 21 cut out in the radial direction at one end to communicate the two ports 12 and 13. 20, a spring 25 that biases the spool 20 in a direction to close the communication between the two ports 12 and 13, and a control current that is applied depending on the vehicle speed, etc., and a spring 25 that biases the spool 20 in a direction that closes communication between the two ports 12 and 13; The slit 21 is provided on the outer periphery of the slit 21 of the spool 20.
There is a structure in which an end plate 40 is fitted to cover the opening end face of the slit 20, a throttle hole 41 is formed in the center of the end plate 40, and a counterbore 38 is formed at the cut end 21a of the slit 20.

In this case, due to the action of the throttle hole 41 formed in the end plate 40, a pressure difference is generated before and after the throttle hole 41, and when the pressure fluid flows from the port 12 to the port 13, a slit is formed in the spool 20. A fluid thrust acts in the direction of narrowing port 21, and conversely pressure fluid flows from port 13 to port 1.
2, a fluid thrust in the direction of opening the slit 21 acts on the spool 20, and no matter what direction the flow is, the slit opening area relative to the suction force of the solenoid 29 is maintained constant, and the unbalance of the fluid force is prevented. This is to correct.

<Problems to be Solved by the Invention> However, in the conventional valve described above, the pressure fluid flows through the throttle hole 41 in the center of the end plate 40, and as shown in FIG. When flowing to port 12, the slit cut end face 21a has a configuration close to a sharp edge, so the flow is less likely to adhere to the slit cut end face 21a, but when flowing from port 12 to port 13, the slit cut end face 21a End face 21
Flow easily adheres to a, so that the force in the closing direction of the spool 20 can be weakened. This force increases as the degree of opening of the slit 21 increases, and eventually exceeds the force in the closing direction (flow force), causing a phenomenon in which the spool 20 is pushed up and the flow rate increases rapidly. As a result, as shown in Fig. 5, a flow rate imbalance occurs in the forward and reverse flow directions, such as the flow rate A when flowing from port 13 to port 12 and the flow rate JIB when flowing from port 12 to port 13. There is a problem with this.

Means for Solving the Problems> The present invention has been made in view of the above-mentioned problems, and its characteristic configuration is that an end plate is provided on the outer periphery of the slit side end of the spool to cover the opening end surface of the slit. A gap is formed on the outer periphery of this end plate to communicate the two ports, and a relief groove is formed on the inner circumferential surface of the valve body outside this gap at a position corresponding to the slit on the circumference. This is what I did.

Effect> With the above configuration, as the spool rises, the narrow part of the gap, that is, the part that functions as an orifice becomes longer, and the differential pressure between the top and bottom increases.

This generates a flow force to suppress the force pushing up the spool, thereby ensuring a flow balance in the forward and reverse flow directions between the two ports.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. In FIG. 1, 10 is a valve body made of a magnetic material. This valve body 10 is fitted into a through hole 32a provided in the peripheral wall of the power cylinder 32 in the radial direction, and
Port 1 opens to the first stream 1i4P1 leading to the left ventricle of 2.
2 and an inner hole 11 communicating with this port 12 is provided. Further, a union 24 made of a non-magnetic material such as stainless steel is screwed onto the valve body 10, and one end of the union 24 is connected to a second flow path P2 leading to the right chamber of the power cylinder 32.
A port 13 is provided which opens into the inner hole 11 at the other end thereof.

A yoke 21 made of a magnetic material is fitted and fixed inside a sleeve 26 which is fixed to the outer end protrusion of the valve body 10 by brazing or the like. A solenoid 29 wound around a bobbin 28 made of a non-magnetic material is provided on the outer periphery of the sleeve 26, surrounding the solenoid 29, and having an inner end connected to the valve body 10.
A cover 15 made of a magnetic material and bonded to the yoke 27 is fixed to the upper end of the yoke 27.

The cylindrical spool 20 is made of a magnetic material and is normally held at its lower end, which is joined to the union 24, by the bias of a spring 25 made of stainless steel and housed in the inner hole 11 of the valve body 10.

A center hole 23 is passed through the center of this spool 20,
Further, a bypass slit 21 cut out in the radial direction is provided at one end with a predetermined length in the axial direction, and communicates with the center hole 23 . The slit 21 blocks communication with the port 12.13 when the spool 20 is at the lower end position, and as the spool 20 is displaced upward, the slit 21 blocks communication with the port 12.13.
13 are connected. A counterbore 38 is formed on the inner peripheral side of the cut end surface 21a of the slit 21 by cutting or the like, and this counterbore groove 38 forms the cut end surface 21a of the slit 21 into a shape similar to a sharp edge.

Further, on the outer periphery of one end of the spool 20 on the slit side,
An annular end plate 40 that covers the opening end surface of the slit 21 is fitted. The outer periphery of this end plate 40 is provided with the valve body 10.
A gap 50 constituting an orifice is formed between the inner circumferential surface of the slit and an aperture hole 41 formed along a diameter line perpendicular to the slit. This aperture hole 41 is the end plate 4
Even in the state where the end face of the end plate 40 is joined to the union ion 24, communication is performed at the joining face to maintain the same pressure on the inside and outside of the end plate 40.

Furthermore, a relief trough 6 is provided on the inner peripheral surface of the valve body 10 outside the gap 50 at a position corresponding to the slit 21 on the circumference.
This is a configuration that does not form 0.

When the linear solenoid valve configured as described above is used in a hydraulic control circuit of a power steering system of an automobile, when a control current corresponding to the vehicle speed is applied from the computer to the solenoid 29, the solenoid 29 moves from the cover 15 to the valve. A magnetic flux is formed passing through the main body 10, spool 20, yoke 27, cover 15, and solenoid 29, and thereby an attractive force proportional to the current applied to the solenoid 29 acts on the spool 20. However, when the vehicle speed is lower than the predetermined speed, the spool 20 is not displaced by the biasing force of the spring 25, and communication between the ports 12 and 13, which communicate with the left and right chambers of the power cylinder 32, is cut off.

When the vehicle speed exceeds a predetermined speed, the suction force of the solenoid 29 overcomes the biasing force of the spring 25 and the spool 2
0 begins to be displaced. As a result, the slit 21 is opened to the port 12, and a bypass passage is formed between the ports 12 and 13. Furthermore, since the opening area of the slit 21 is linearly displaced according to the current applied to the solenoid 29, the bypass flow rate between the left and right chambers of the power cylinder increases as the vehicle speed increases, and as a result, the vehicle speed increases. The steering force changes linearly in response to the change in speed, resulting in high speed.

By the way, the pressure fluid passing between the ports 12 and 13 flows through a gap 50 formed on the outer periphery of the end plate 40.
A pressure difference is generated before and after the gap 50 by the throttling action of
As a result, when pressure fluid flows from port 12 to port 13, fluid thrust acts on spool 20 in the direction of narrowing slit 21, and conversely, when pressure fluid flows from port 13 to port 12, fluid thrust acts on spool 20. slit 2
A fluid thrust acts in the direction of opening 1.

When the pressure fluid flows from the port 12 to the port 13 and a fluid thrust in the direction of narrowing the slit 21 acts on the spool 20, the flow adheres to the slit cut end surface 21a and a force (flow force) in the direction of closing the spool 20 is applied. However, as the spool 20 increases its opening degree due to the suction force of the solenoid 29, the gap formed by the gap 50 is The length of the orifice becomes longer as shown by 1 in FIG. 2, and the differential pressure between the upper and lower sides increases. This increases the flow force and suppresses the force pushing up the spool 20. Therefore, regardless of whether the flow direction of the pressure fluid flowing between the ports 12 and 13 is forward or reverse, the opening area of the slit 21 relative to the suction force of the solenoid 29 is maintained substantially constant, and the flow rate is controlled to be balanced.

<Effects of the Invention> As described above, in the present invention, an end plate that covers the open end of the slit is fitted to the outer periphery of the slit side end of the spool, and a gap is formed on the outer periphery of this end plate to perform an orifice action. A relief gap corresponding to the slit on the circumference is formed on the inner peripheral surface of the valve body outside this gap, and a force pushing up the spool in the opening direction exceeds the flow force in the closing direction of the spool. However, as the opening degree of the spool increases, the length of the orifice formed between the spool and the gap is increased, and the flow force is increased to suppress the spool from being pushed up. The flow rate can be stabilized in both the forward and reverse flow directions of the pressure fluid between the two ports, and has the effect of preventing the spool from rapidly moving in the opening direction. Therefore, when the linear solenoid valve of the present invention is applied to a vehicle speed-sensitive power steering system, it is possible to accurately eliminate the imbalance in steering force to the left of the steering wheel when cutting cloth.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a linear solenoid valve showing an embodiment of the present invention, FIG. 2 is an enlarged view of the main part of the present invention in FIG. 1, FIG. 3 is a sectional view of a conventional linear solenoid, and FIG. FIG. 5, an enlarged view of the main part, is a flow characteristic diagram of a conventional linear solenoid valve. 10... Valve body, 11... Inner hole, 12.13.
... Port, Pl, P2 ... Channel, 20 ... Spool, 21 ... Slit, 21a ... Cut end surface, 2
5...Spring, 29...Solenoid, 40...
・End plate, 50...Gap, 60...Escape.

Claims (1)

[Claims] The valve body has two ports each communicating with two passages through which high-pressure fluid and low-pressure fluid selectively flow, and has an inner hole through which these two ports open, and a valve body that can be slid into this inner hole. a cylindrical spool that is fitted and has a bypass slit cut out in the radial direction at one end that connects the two ports; a spring that biases the spool in a direction that closes communication between the two ports; In the linear solenoid valve, the linear solenoid valve includes a solenoid to which a control current is applied and which draws the spool in a direction that communicates the two ports in accordance with the control current. An end plate is fitted to cover the opening end face of the valve body, a gap is formed on the outer periphery of this end plate to communicate the two ports, and a relief groove is formed on the inner circumferential surface of the valve body outside this gap so that the slit and the circumference A linear solenoid valve characterized by being formed at a corresponding position above.