JPH044258Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a spool-type electromagnetic pressure control valve, and particularly to a technique for increasing fluid pressure that can be controlled by a constant control force of a solenoid.

2. Description of the Related Art Electromagnetic pressure control valves are already known which control the pressure of a fluid to a level corresponding to the magnitude of the excitation current by controlling the excitation current of a solenoid. For example, the one described in Utility Model Application No. 134529/1983 is one. This control valve has a spool slidably and substantially liquid-tightly fitted into a valve hole in a housing having a high pressure port, a low pressure port, and a control pressure port. While the magnetic control force of the solenoid is applied to the spool, the tip surface of the reaction piston, which extends axially from one end surface of the spool, is exposed to the atmosphere. A reaction force is applied to the spool having a magnitude equal to the product of the cross-sectional area and the fluid pressure within the valve bore. Therefore, the spool is moved based on the control force and the reaction force, and the control pressure port is selectively communicated with the high pressure port and the low pressure port, so that the fluid pressure in the control pressure port is increased by the excitation current of the solenoid. The height is controlled to correspond to the size of. In other words, this control valve performs pressure control while maintaining the balance of the spool forces expressed by the following equation.

S=PA+R...(1) S=CNI...(2) However, S: Suction force of the solenoid on the spool P: Fluid pressure in the valve hole and control pressure port (fluid pressure difference between the control pressure port and the low pressure port) A: Cross-sectional area of the reaction piston R: Sliding resistance of the reaction piston and spool C: Constant N: Number of turns of the solenoid I: Excitation current to the solenoid And the sliding resistance R of the reaction piston and spool can be ignored. If it is small enough, P=(CN/A)I...(3) can be obtained from equations (1) and (2). That is, the fluid pressure P in the valve hole and the control pressure port is proportional to the number of turns N of the solenoid and the exciting current I, and is inversely proportional to the cross-sectional area A of the reaction piston. Therefore, in order to increase the controllable fluid pressure P of this control valve, it is necessary to increase the number of turns N and the exciting current I, or to make the cross-sectional area A of the reaction piston smaller.

Problems to be solved by the invention However, there is a limit to increasing the number of turns of the solenoid and the excitation current. For example, in pressure control valves used in automobiles, the working voltage,
There are severe restrictions such as operating temperature and installation space.
Inevitably, the number of turns of the solenoid and the excitation current are limited, and the spool attraction force by the solenoid is limited to about 1 kg.

Furthermore, there is a limit to reducing the cross-sectional area of the reaction piston. In order to reduce the sliding resistance between the reaction piston and the housing in which it is fitted, it is necessary to achieve liquid tightness with the housing through a metal-to-metal seal, and both sliding surfaces must have high dimensions. Must be processed with precision. Therefore, advanced technology is required to process the reaction piston, and it is said that the diameter of the reaction piston that can be processed using current technology is about 3 mm or more.

Based on the above numerical values, the fluid pressure of the control pressure port is calculated from the above equation (3) to be about 10-odd kg/cm ² . Therefore, to control hydraulic pressure exceeding that value,
It was considered impossible to apply this type of control valve.

Means for Solving the Problems In order to solve the above problems, the present invention provides a spool-type electromagnetic pressure control valve equipped with the housing, a spool, a solenoid, and a reaction piston, in which the reaction piston applies a reaction force to the spool. A reaction force reduction device is provided to reduce the reaction force, thereby increasing the diameter of the reaction force piston relative to the control force of the solenoid.

For example, when the reaction force piston and the spool are coaxial and integrated, the reaction force reduction device is installed coaxially with the spool and uses the fluid pressure difference between the control pressure port and the low pressure port to reduce the reaction force on the reaction force piston. It is preferable to include a reduction piston that operates in a direction opposite to that of the reduction piston, and a link mechanism that connects the reduction piston and the spool so as to be able to move slightly relative to each other and transmits the operating force of the reduction piston to the spool. It is also possible to make the reaction force piston separate from the spool and to use the reaction force reduction device as a lever mechanism that reduces the operating force of the reaction force piston at a fixed ratio and transmits it to the spool.

Operation and Effect If the reaction force reduction device is provided as described above, the reaction force that the reaction force piston applies to the spool is reduced.

When the reaction force reduction device includes a reduction piston and a link mechanism, a part of the actuation force (reaction force) of the reaction force piston is canceled by the actuation force of the reduction piston, and the reaction force reduction device In the case of a lever mechanism, the lever mechanism reduces the reaction force at a constant rate and transmits it to the spool.

Therefore, in order to increase the controllable fluid pressure without increasing the control force of the solenoid, there is no need to reduce the diameter of the reaction piston to reduce the reaction force of the reaction piston itself. Therefore, the reaction piston can be made to have a diameter that is easy to manufacture, and processing time and manufacturing costs can be reduced.

Furthermore, along with this easier manufacturing, the dimensional accuracy of the outer circumferential surface of the reaction piston is more stable, and fluctuations in sliding resistance with the housing due to dimensional variations are reduced, improving the operational stability of the spool during pressure control. Further improved effects can be obtained.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is a system diagram conceptually showing an electrically controlled hydraulic brake system for automobiles. A spool type electromagnetic hydraulic control valve 10, which is an embodiment of the present invention, uses an accumulator 12 as a hydraulic pressure source to control the brake. It is provided to control the hydraulic pressure of the wheel cylinder 14. The pedal force on the brake pedal 16 as a brake operating member is detected by the pedal force sensor 18,
An excitation current proportional to the pedal force on the brake pedal 16 is supplied to the solenoid 22 of the hydraulic pressure control valve 10 from a solenoid control circuit 20 connected to the pedal force sensor 18 , and the hydraulic pressure in the wheel cylinder 14 is adjusted to the pressure on the brake pedal 16 . The height is controlled in proportion to the pedal effort. Brake fluid pumped up from a reservoir 24 by a pump 26 is stored in the accumulator 12, and the hydraulic pressure in the accumulator 12 is detected by a hydraulic pressure sensor 28, and the output signal of this hydraulic pressure sensor 28 is The motor 32 is controlled by the motor control circuit 30 based on this, so that the hydraulic pressure within the accumulator 12 is maintained within a certain range.

The hydraulic control valve 10 includes a housing 40 made of non-magnetic material. Inside the housing 40, a valve hole 42 and a cylinder bore 44 having a smaller diameter than the valve hole 42 are formed coaxially and in communication with each other. A hollow spool 48 is slidably fitted into the valve hole 42, and one end of the spool 48 is closed to form a reaction piston 50.
On the other hand, a reduction piston 52 is fitted into the cylinder bore 44 so as to be slidable in the axial direction and in a substantially liquid-tight manner. Further, the clearance between the outer circumferential surface of the spool 48 and the inner circumferential surface of the valve hole 42 is extremely small, 10 μm or less in diameter, and a metal-to-metal seal is formed by these outer circumferential surfaces and inner circumferential surfaces. Similarly, the outer peripheral surface of the reduction piston 52 and the inner peripheral surface of the cylinder bore 44 form a metal-to-metal seal. The spool 48 is made of a magnetic material, and an appropriate number of annular grooves (not shown) are formed on the outer circumferential surface of the spool 48 so that the liquid pressure acts almost evenly on the entire circumference.
8 is designed to slide easily. Similarly, although not shown in the drawings, the reduction piston 52 has an appropriate number of annular grooves formed on its outer peripheral surface so that it can slide easily.

Housing 40 includes a high pressure port 60 connected to accumulator 12 , a low pressure port 62 connected to reservoir 24 , and a control pressure port 64 connected to wheel cylinder 14 . The spool 48 has a dead-end axial hole 66, and a first radial hole 68 and a second radial hole 70 extending radially from the axial hole 66 and opening to the outer circumferential surface.
It is equipped with

A spring 7 is provided between the open end of the spool 48 and a yoke 72 made of magnetic material fixed to the housing 40.
4 is disposed to urge the spool 48 toward the original position shown. When the spool 48 is in its original position, the first radial hole 68 communicates with the low pressure port 62 and the control pressure port 64, resulting in the valve hole 42 and the wheel cylinder 14.
The hydraulic pressure is equal to the hydraulic pressure (atmospheric pressure) in the reservoir 24. However, if the excitation current is supplied to the solenoid 22 and the yoke 72 is magnetized, the magnetic attraction force acts on the spool 48 as a control force, and the spool 48 resists the urging force of the spring 74 and becomes the first
Move to the left in the diagram. This breaks communication between the first radial hole 68 and the low pressure port 62, and if the spool 48 moves further to the left, the second radial hole 70 comes into communication with the high pressure port 60. During this time, the control pressure port 64 is always in communication with the valve hole 42 via the first radial hole 68. The relative positions of each port 60, 62, 64 and the first and second radial holes 68, 70 are thus determined. Note that the reason why a hole is formed in the yoke 72 to pass through it in the axial direction is to cool the yoke 72 by introducing brake fluid into this hole.

A ring-shaped stopper 76 made of a non-magnetic material is fixed to the open end of the spool 48 on the yoke 72 side. When the stopper 76 comes into contact with the yoke 72, the spool 48 is directly connected to the yoke 72.
2 to prevent it from being adsorbed.

The attenuation piston 52 has a low pressure chamber 80 that constantly communicates the space within the cylinder bore 44 with the reservoir 24.
and a control pressure chamber 8 that is always in communication with the control pressure port 64.
It is divided into 2. The reaction piston 50 and the reduction piston 52 are connected by a link mechanism 88 within the low pressure chamber 80 . In addition, spool 4
A small amount of brake fluid leaks from the small clearance between the valve hole 80 and the valve hole 42 from the low pressure chamber 80 to the reservoir 24.
be returned to. In this embodiment, the link mechanism 88 and the reduction piston 52 constitute a reaction force reduction device. The link mechanism 88 includes a first link 90 and a second link 92 that protrude in the axial direction from the end surfaces of the reaction piston 50 and the reduction piston 52, which face each other across the low pressure chamber 80. . These first and second links 9
0 and 92 are connected by inserting a pin into a circular hole having a diameter slightly larger than that of the pin, and the force is transmitted between the reaction piston 50 and the reduction piston 52, and the pin and the circular hole are connected to each other. A very small amount of relative movement between the first and second links 90, 92 is allowed by the distance between them.

Therefore, even if the reaction force piston 50 has a relatively large diameter and therefore a large reaction force is applied to the spool 48, the actuation force (reaction force) generated in the reduction piston 50 cancels out a part of the reaction force. As a result, a reaction force having a size equal to the product of the hydraulic pressure difference between the control pressure chamber 82 and the low pressure chamber 80 and the pressure receiving area difference between the reaction force piston 50 and the reduction piston 52 is generated in the spool 48. become.

The operation of the device of this embodiment will be explained.

According to the pedal force on the brake pedal 16 detected by the pedal force sensor 18, the solenoid control circuit 2
0 supplies an excitation current to the solenoid 22 with a magnitude proportional to the pedal force. Then, the spool 48 is attracted by the magnetic attraction force of the yoke 72, and the high pressure port 60 and the control pressure port 64 communicate with each other via the second axial hole 70. The high-pressure brake fluid is then supplied to the wheel cylinder 14.

The present invention can also be implemented in the embodiment shown in FIG.
This spool-type electromagnetic hydraulic pressure control valve 98 has many points in common with the hydraulic pressure control valve 10 of the previous embodiment, so common elements are given the same reference numerals and detailed explanations are omitted, and different Only parts will be explained in detail.

A valve hole 42 and a cylinder bore 102 whose axial direction is parallel to and non-coaxial with the valve hole 42 and which is isolated from the valve hole 42 are formed in the housing 100 . A spool 112 is slidably fitted into the valve hole 42 , while a spool 112 is slidably fitted into the valve hole 42 .
A reaction piston 114 is axially slidably and substantially liquid-tightly fitted into the housing 100, resulting in a control pressure chamber 116 in constant communication with the control pressure port 64 and a reservoir. A low pressure chamber 118 is formed which is in constant communication with 24.

Furthermore, the spool 112 and the reaction piston 1
A first link 120 and a second link 122 are provided to protrude in the axial direction from the end faces of the control pressure chambers 116 of 14, respectively. In addition, a linear lever 13 rotatable around a support shaft 124 is provided in the control pressure chamber 116.
0 is placed. The end of this lever 130 that is a distance L ₁ away from the support shaft 110 is the first link 120.
A substantially intermediate portion spaced apart from the support shaft 114 by a distance L ₂ is rotatably connected to the second link 122 .
The first and second links 120, 122 and the lever 130 constitute a lever mechanism 132 as a reaction force reduction device.

The first and second links 120, 122 and the lever 130 are connected to each other by inserting a pin into a circular hole having a diameter slightly larger than the diameter of the pin, and between the spool 112 and the lever 130 and the reaction piston 102. Force is transmitted between the levers 130, and a small amount of relative movement between the first and second links 120, 122 and the lever 130 is allowed by the space between these pins and the circular holes.

Note that when the tip end surface of the first link 120 comes into contact with the inner surface of the housing 100 that forms the control pressure chamber 116, the first link 120 connects the low pressure port 62 and the control pressure port 6.
4 can be connected to each other through the first radial hole 68 of the spool 112. Furthermore, in this state, the lever mechanism 132 is laid out so that the lever 120 is orthogonal to the axial direction of the spool 112 and the reaction piston 102.

Therefore, the spool 112 has a preset value of 1 for the actuation force (reaction force) of the reaction force piston 114.
It is transmitted with a reduced magnitude multiplied by the smaller lever ratio L ₂ /L ₁ . The spool 112 in this embodiment has the hydraulic pressure of the valve hole 42 and the control pressure chamber 11 on both end faces.
6, the valve hole 42 and the control pressure chamber 11
6 is always at the same pressure, so this spool 1
No reaction force is generated on 12 itself.

It should be noted that in both embodiments, the connecting body of the two sliding members (spool 48 - reduction piston 52, spool 112 - reaction force piston 114) spanning between the valve hole and the cylinder bore with different inner diameters is separated. , since relative movement in the radial direction of both sliding members is allowed, there is no need to increase the concentricity or parallelism of both sliding members, and the outer diameter of each sliding member and each valve hole or cylinder bore To manufacture at low cost a hydraulic control valve 10, 98 in which it is easy to make the clearance between these parts extremely small, and the internal leakage is negligible, since the dimensional accuracy of the inner diameter of the valves 10 and 98 can be made very small. I can do it.

One embodiment of the present invention has been described in detail above, but
This is literally an example, and it goes without saying that the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view schematically showing a spool type electromagnetic hydraulic control valve which is an embodiment of the present invention.
It is also a system diagram of an electrically controlled hydraulic brake system for an automobile including the hydraulic pressure control valve. Figure 2 shows
FIG. 3 is a front sectional view schematically showing a spool-type electromagnetic hydraulic control valve according to another embodiment of the present invention. 10... Spool type electromagnetic hydraulic control valve, 40...
Housing, 42...Valve hole, 44...Cylinder bore, 48...Spool, 50...Reaction force piston,
52... Reduction piston, 60... High pressure port, 6
2...Low pressure port, 64...Control pressure port, 72
... Yoke, 74 ... Spring, 88 ... Link mechanism, 98 ... Spool type electromagnetic hydraulic control valve, 1
00...Housing, 102...Cylinder bore,
112... Spool, 114... Reaction piston,
132...Lever mechanism.

Claims (1)

[Claims for Utility Model Registration] (1) A housing having a high pressure port, a low pressure port, and a control pressure port, and a spool slidably and substantially liquid-tightly fitted into a valve hole in the housing; The control force includes a solenoid that applies a magnetic control force to the spool, and a reaction piston operated by a fluid pressure difference between the control pressure port and the low pressure port, and has a size corresponding to the fluid pressure difference. reaction force means for applying a reaction force in the opposite direction to the spool, the spool is moved based on the control force and the reaction force, and the control pressure port is connected to the high pressure port and the low pressure port. A spool type electromagnetic pressure control valve in which the fluid pressure of the control pressure port is controlled to a height corresponding to the magnitude of the excitation current of the solenoid by being selectively communicated, wherein the reaction force piston applies to the spool. A spool-type electromagnetic pressure control valve, characterized in that a reaction force reduction device is provided to reduce reaction force, thereby increasing the diameter of the reaction force piston relative to the control force. (2) The reaction force piston is integrated with the spool, and the reaction force reduction device is disposed coaxially with the spool, and the reaction force reduction device is arranged coaxially with the spool to reduce the reaction force by a fluid pressure difference between the control pressure port and the low pressure port. A utility model registration that includes a reduction piston that operates in the opposite direction to the reaction piston, and a link mechanism that connects the reduction piston and the spool so as to be able to move slightly relative to each other and transmits the operating force of the reduction piston to the spool. A spool type electromagnetic pressure control valve according to claim 1. (3) The reaction force piston is provided separately from the spool, and the reaction force reduction device is a lever mechanism that reduces the operating force of the reaction force piston at a fixed ratio and transmits it to the spool. A spool type electromagnetic pressure control valve according to claim 1 of a certain utility model registration claim.