JPH04236611A - Spool type pressure control valve - Google Patents

Abstract

PURPOSE:To prevent oscillation of a spool and to improve the stability of the characteristics of a spool type pressure control valve by reducing the force to the spool of a fluid flowing from a high pressure port to a control pressure port in the control valve as much as possible. CONSTITUTION:A first annular groove 12a always connected to a control valve port 11d, a second annular groove 12b selectively connected to a high pressure port 11e, and a third annular groove 12c selectively connected to a low pressure port 11f are provided on the outside periphery of a spool 12, and a connection hole 12d in the axial direction to connect respective annular grooves 12a to 12c is provided. The width in the axial direction of each of annular grooves 12a to 12c is reduced to reduce an angle theta of inflow of the fluid very much, thereby reducing the fluid force to the spool 12 very much.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spool type pressure control valve.

0002

[Prior Art] As shown in the specification and drawings of Japanese Patent Application No. 2-182932 filed by the present applicant, a spool type pressure control valve has an inner hole extending in the axial direction and A housing having a high pressure port, a low pressure port, and a control pressure port located at a predetermined interval in the axial direction and communicating with the inner hole, and slidable in the inner hole of the housing in a liquid-tight manner and in the axial direction. A spool that is fitted and slid in the axial direction selectively communicates the control pressure port with the low pressure port and the high pressure port; a pressing force generating means for pressing the spool in a direction to cut off communication between the control pressure port and the high pressure port; There is a spool-type pressure control valve that includes a control force applying means for applying a control force to the spool that counteracts the pressing force.

In this type of spool-type pressure control valve, when the spool is not in operation, the spool is in the set return position, and communication between the control pressure port and the high pressure port is cut off, and communication between the control pressure port and the low pressure port is cut off. are in communication. When the solenoid of the control force applying means is energized in such a state, the control force applying means generates a driving force proportional to the excitation current to the solenoid to counteract the pressing force from the pressing force generating means against the spool. Gives control. For this reason, the spool slides with a control force proportional to the excitation current of the solenoid, cutting off communication between the control pressure port and the low pressure port, and communicating the control pressure port and the high pressure port.

As a result, a high hydraulic pressure is applied to the control pressure port from the high pressure port side, and the same hydraulic pressure is applied to the pressing force generating means to generate a pressing force proportional to the hydraulic pressure. The same pressing force is applied to the spool as an acting force that opposes the above control force, and the spool stops when these control forces and the pressing force are balanced, and the hydraulic pressure on the control pressure port side is proportional to the excitation current. Control to a predetermined pressure.

[0005] Generally, in this type of spool type pressure control valve, as shown in FIG.
, 1b, and an annular communication path 2b having a predetermined length in the axial direction is formed on the outer periphery of the small diameter portion 1c of the spool 1 within the inner hole 2a of the housing 2. . A control pressure port 2c is always in communication with the communication passage 2b, and a low pressure port 2d is connected to the communication passage 2b when the control valve is not in operation.
When the control valve is activated, the spool 1 slides in the axial direction, cutting off communication with the low pressure port 2d and communicating with the high pressure port 2e.

[0006]

However, in this pressure control valve, when the communicating passage 2b communicates with the high pressure port 2e due to the axial sliding of the spool 1, the high pressure fluid on the high pressure port 2e side flows as shown in FIG. It flows into the communication path 2b at an angle θ. As a result, the high pressure fluid flowing into the spool 1
A fluid force of F=2CsinθaΔP is applied to the force. However, a is the inflow side opening area, and θ is the fluid inflow angle. The fluid force F acts against the control force on the spool 1, and becomes a factor that causes vibration of the spool 1 in the pressure control valve, and due to this factor and other factors, the characteristics of the pressure control valve are may become unstable. Therefore, an object of the present invention is to prevent the above-mentioned vibration and characteristic instability by reducing the fluid force F of the high-pressure fluid to zero or as close to zero as possible in this type of spool-type pressure control valve. be.

[0007]

[Means for Solving the Problems] The present invention has an inner hole extending in the axial direction, and has a high pressure port, a low pressure port, and a control pressure port located at a predetermined interval in the axial direction and communicating with the inner hole. a housing; and a spool that is fluid-tightly and slidably inserted into the inner hole of the housing and selectively communicates the control pressure port with the low pressure port and the high pressure port by sliding in the axial direction. and a pressing force generating means located on the negative end side of the spool, which presses the spool in a direction to cut off communication between the control pressure port and the high pressure port by the action of hydraulic pressure of the control pressure port, and the spool. A spool-type pressure control valve, which is located at the other end and includes a control force applying means that generates a driving force proportional to the excitation current to the solenoid and applies a control force to the spool that counteracts the pressing force. and a first annular groove constantly communicating with the control pressure port, a second annular groove selectively communicating with the high pressure port, and a third annular groove selectively communicating with the low pressure port on the outer periphery of the spool. The spool is characterized in that a groove is provided and a communication hole is provided in the axial direction of the spool to allow these annular grooves to communicate with each other.

[0008]

In the spool type pressure control valve having such a structure, communication between the control pressure port and the low pressure port is achieved through the first annular groove, the third annular groove and the communication hole, and the control pressure port and the high pressure port are communicated with each other through the first annular groove, the third annular groove and the communication hole. Communication with the first annular groove and the second annular groove
This is done by an annular groove and a communicating hole. Therefore, the spool does not require an annular communication passage having a predetermined length in the axial direction, which is always in communication with the control pressure port, and which communicates with or is located close to either the low pressure port or the high pressure port.

[0009]

[Effects of the Invention] Therefore, each annular groove can be made extremely short in length in the axial direction (that is, extremely narrow in width),
As a result, the inflow angle θ of the pressure fluid into the annular groove can be made zero or close to zero, and the fluid force acting in the axial direction of the spool can be made zero or close to zero, thereby preventing the occurrence of spool vibration. At the same time, the stability of the characteristics of the pressure control valve can be improved.

0010

[Embodiments] Hereinafter, embodiments of the present invention will be explained based on the drawings. Fig. 1 shows a spool type pressure control valve 1 according to the present invention.
0 is shown. The pressure control valve 10 is used in a hydraulic brake system for an automobile, and is incorporated into the brake system as shown in FIG. The brake system includes a master cylinder 21 and a change valve 22.
A hydraulic system leading to the wheel cylinder 23 of each wheel via the accumulator 24, and the pressure control valve 10 according to this embodiment.
There are two systems: a hydraulic pressure path and a hydraulic pressure path that passes through the change valve 22 and reaches the hole cylinder 23 of each wheel. Although the change valve 22 and the pressure control valve 10 are provided for each wheel cylinder, only one of each is shown. The reservoir 2 is connected to the accumulator 24 by a hydraulic pump 25.
6 brake fluid is always stored within the constant fluid pressure range,
The brake fluid is applied to the high pressure port side of a pressure control valve 10, which will be described later.

In this brake system, the pedal force on the brake pedal 27 is detected by the pedal force sensor 31, and
The detection signal is input to the controller 32. The controller 32 calculates an excitation current for the pressure control valve 10 based on the pedal force detection signal and the acceleration detection signal input from the acceleration sensor 33, and sends a command signal of the excitation current to the drive circuit 34.
to energize the solenoid of the pressure control valve 10. Thereby, brake fluid pressure corresponding to the depression force of the brake pedal 27 is applied to the wheel cylinder 23, and each wheel is appropriately braked.

Furthermore, when an abnormality occurs in the hydraulic system such as the pressure control valve 10, brake hydraulic pressure is applied from the master cylinder 21 to the wheel cylinder 23 according to the depression force of the brake pedal 27 by the switching action of the change valve 22. to compensate for abnormalities in the hydraulic system.

As shown in FIG. 1, the pressure control valve 10 includes a housing 11, a spool 12, and a pressing force generating means 1.
0a and control force applying means 10b. The pressing force generating means 10a is composed of a reaction force piston 13 and a compression spring 14, and the control force applying means 10b is composed of an operating piston 15, a solenoid 16, and a yoke 1.
7 and a magnet 18.

The housing 11 has an inner bore 11 extending in the axial direction.
a, an accommodation hole 11b of the pressing force generating means 10a located coaxially at one end of the inner hole 11a, and an accommodation chamber 11c of the control force applying means 10b coaxially located at the other end of the inner hole 11a; It also has a control pressure port 11d, a high pressure port 11e, and a pair of low pressure ports 11f and 11g. Each of these ports 11d to 11g is an inner hole 11a.
The inner hole 1 is located at a predetermined interval in the axial direction along
1a, respectively. Further, a branch port 11h opens in the accommodation hole 11b, and a drain port 11i opens in the accommodation chamber 11c.

In the housing 11, the control pressure port 11d is connected to the wheel cylinder 23, the high pressure port 11e is connected to the accumulator 24, and the low pressure ports 11f and 11g are connected to the reservoir 26. Further, the branch port 11h is connected to the control pressure port 11d, and the drain port 11i is connected to the reservoir 26.

The spool 12 has a cylindrical shape as shown in FIGS. 1 and 2, and has first, second, and third annular grooves 12a, 12b, and 12c formed on its outer periphery. Each annular groove 1
2a to 12c are positioned along the inner hole 11a at predetermined intervals in the axial direction. Further, a plurality of communication holes 12d are formed in the spool 12 in the axial direction to communicate the respective annular grooves 12a to 12c, and each communication hole 12d is formed at the lower end of the spool 12.
A plug 12e is fitted to close the opening. The spool 12 is fitted into the inner hole 11a of the housing 11 in a fluid-tight manner and is slidable in the axial direction. First annular groove 12a, second annular groove 12b and third annular groove 12c
correspond to the first, second, and third annular grooves of the present invention, respectively.

A reaction piston 13 constituting the pressing force generating means 10a is slidably inserted into the accommodation hole 11b, and is urged toward the spool 12 by a compression spring 14. A branch port 11h is opened at the opposite end of the reaction piston 13 within the accommodation hole 11b. As a result, the reaction piston 13 is connected to the compression spring 14 and the branch port 11h.
The spool 1 is energized by the control hydraulic pressure applied from the spool 1.
Resiliently abuts on the other end of 2.

Yoke 1 constituting control force applying means 10b
7 is fitted into the storage chamber 11c, and an annular magnet 18 is fixed to the outer periphery of the intermediate portion in the axial direction. The actuating piston 15 is fitted coaxially into the yoke 17 so as to be able to slide in the axial direction, and its lower end abuts the other end of the spool 12 to receive the spool 12. The actuating piston 15 has an annular solenoid 16 on the other end side of the cylinder, and is located at the retreating end shown in FIG. 1 when the solenoid 16 is not energized.

In a brake system equipped with the pressure control valve 10 having such a configuration, the pressure control valve 10 is in the state shown in FIG. 1 when the brake pedal 27 is not depressed. That is, the solenoid 16 constituting the control force applying means 10b is in a de-energized state, and the actuating piston 15
is located at the retreating end. In this state, the first annular groove 12a of the spool 12 communicates with the control pressure port 11d, and the third annular groove 12c communicates with the low pressure port 11.
f, and communicates with the second annular groove 12b and the high pressure port 11e.
Communication with has been cut off. Therefore, control pressure port 1
1d communicates with the reservoir 26, and the wheel cylinder 23 has the same atmospheric pressure as the brake fluid pressure in the reservoir 26.

[0020] When the depression operation of the brake pedal 27 is started, an excitation current corresponding to the depression force on the brake pedal 27 is applied to the solenoid 16, and the actuating piston 15 slides toward the - end side in accordance with the excitation current. . As a result, the spool 12 slides against the compression spring 14 and blocks the third annular groove 12c from communicating with the low pressure port 11f, and when it slides further, it connects the second annular groove 12b to the high pressure port 11e. . During this time, the first annular groove 12a
always maintains communication with the control pressure port 11d. As a result, the control pressure port 11d becomes the high pressure port 11e.
A high control hydraulic pressure is applied to the wheel cylinder 23.

[0021] Due to the communication between the control pressure port 11d and the high pressure port 11e, the internal pressure in the accommodation hole 11b also increases, and the reaction piston 13 is urged together with the compression spring 14, thereby pressing the spool 12 toward the operating piston 15. Therefore, when the pressing force of the actuating piston 15 is larger than the pressing force of the reaction piston 13, the spool 12 slides toward the - end, but when it is smaller, it slides toward the other end for control. Pressure port 1
The control pressure port 11d is cut off from communicating with the high pressure port 11e, and further sliding in the same direction causes the control pressure port 11d to communicate with the low pressure port 11f. Therefore, the spool 12 finally stops when the pressing forces of the actuation piston 15 and the reaction piston 13 are balanced, and the control pressure port 11
The hydraulic pressure of d is controlled according to the excitation current, and the controlled hydraulic pressure is applied to the wheel cylinder 23.

By the way, in the pressure control valve 10, as shown in an enlarged view in FIG.
The control pressure port 11d and the high pressure port 11e communicate with each other through the first annular groove 12a, the second annular groove 1
2b and the communication hole 12d. For this reason, the spool 12 always communicates with the control pressure port 11d and has a predetermined length in the axial direction that communicates with or is close to either the low pressure port 11f or the high pressure port 11e, which is indispensable in the past. An annular communication path becomes unnecessary.

Therefore, each of the annular grooves 12a to 12c can be made to have an extremely short length in the axial direction, that is, an extremely narrow width, so that the inflow angle θ of the pressure fluid into the annular groove can be adjusted as indicated by the arrow in FIG. As shown, the fluid force acting in the axial direction of the spool 12 can be brought to zero or close to zero, thereby preventing vibration of the spool 12 and reducing the pressure of the pressure control valve 10. Stability can be improved by eliminating factors that affect the stability of characteristics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a pressure control valve according to an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view showing essential parts of the pressure control valve.

FIG. 3 is a system diagram of a brake system using the same pressure control valve.

FIG. 4 is a partially enlarged sectional view corresponding to FIG. 2 of a conventional pressure control valve.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10...Pressure control valve, 10a...Pushing force generation means, 10b...
Control force applying means, 11...housing, 11a...inner hole, 1
1d...Control pressure port, 11e...High pressure port, 11f...Low pressure port, 12...Spool, 12a, 12b, 12c...
Annular groove, 13... Reaction piston, 14... Compression spring,
15... Working piston, 16... Solenoid, 21... Master cylinder, 22... Change valve, 23... Wheel cylinder, 24... Accumulator, 27... Brake pedal,
32...Controller.

Claims (1)

[Claims] 1. A housing having an axially extending inner hole, a high pressure port, a low pressure port, and a control pressure port located at a predetermined interval in the axial direction and communicating with the inner hole; a spool that is fluid-tightly and slidably inserted into the hole and selectively communicates the control pressure port with the low pressure port and the high pressure port by sliding in the axial direction; and an end side of the spool. a pressing force generating means located at the other end of the spool that presses the spool in a direction to cut off communication between the control pressure port and the high pressure port by the action of hydraulic pressure of the control pressure port; and a solenoid located at the other end of the spool. A spool-type pressure control valve comprising a control force applying means for generating a driving force proportional to an excitation current to apply a control force to the spool to counter the pressing force, a first annular groove that constantly communicates with the control pressure port, a second annular groove that selectively communicates with the high pressure port, and a third annular groove that selectively communicates with the low pressure port; A spool-type pressure control valve characterized in that a communication hole is provided for communicating these annular grooves with each other in the axial direction.