JPH0539880A - Electric motor operated pressure control valve - Google Patents

Abstract

PURPOSE:To improve durability in a screw mechanism by giving output pressure of a motor-driven pilot pressure control valve to a pressure governing piston so as to move the pressure governing piston. CONSTITUTION:Under a condition that a spring bearing 62 of a motor-driven pilot pressure control valve 41 is on the rightward movement final edge and pressure is set according to the lowest spring force of the first/the second pressure governing springs 31 and 32 in a pilot valve 27, an electric motor 56 is rotated in one direction by a prescribed quantity. Thereby, the spring bearing 62 moves leftward by a prescribed distance, and the second pressure governing spring 53 is deflected, so that spring force is increased. Thereby, pressure of an entrance chamber 47 in the electrically driven pilot pressure control valve 41 is heightened by the extent that the spring force of the second pressure governing spring 53 is increased. This pressure acts on a pressure governing piston 37 through a pressure governing chamber 38, and moves the piston leftward while deflecting the pressure governing springs 31 and 32 until it can be balanced with the spring force. Thereby, pressure of an entrance chamber 28 in the pilot relief valve 27 is heightened due to the increased spring force of the pressure governing springs 31 and 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor operating pressure control valve for changing the set pressure of a fluid circuit by changing the spring force of a pressure adjusting spring in a pilot pressure control valve by an electric motor.

[0002]

2. Description of the Related Art Conventionally, in this type of electric motor operating pressure control valve, the rotational output from the electric motor is converted into an axial displacement by a screw and transmitted to a spring bearing for receiving a pressure adjusting spring, whereby the pressure adjusting spring The spring force is changed by the rotation of the electric motor so that the set pressure can be changed. For example, it is widely used as described in Japanese Utility Model Laid-Open No. 1-155519.

[0003]

The present inventors have tried to apply such a structure to the pressure adjusting spring of the pilot pressure control valve in the pilot operated pressure control valve. Up to 700 kg /
In the case where the pressure is frequently changed to a high pressure state of about cm ² , there is a problem that the spring force of the pressure adjusting spring is increased, friction is increased, and the screw portion is worn in a short period of time and cannot be put to practical use. The present invention solves such a problem, and realizes a motor operating pressure control valve having excellent durability by reducing the spring force of a pressure regulating spring whose spring force is changed by the electric motor. ..

[0004]

Therefore, the present invention is movable so as to open and close between the inlet passage and the outlet passage, receives the pressure from the inlet passage in the opening direction, and the pressure controlled in the pilot chamber in the closing direction. A main valve having a main valve body that receives
A pilot pressure control valve for controlling the pressure in the pilot chamber according to the spring force of the first pressure adjusting spring is provided, and the pilot pressure control valve changes the amount of deflection of the first pressure adjusting spring by movement to change the spring force. A pressure piston is provided, which outputs a pressure corresponding to the spring force of the second pressure adjusting spring, and the second pressure adjusting spring changes the deflection amount by the rotation of the electric motor through a screw mechanism that converts the rotational displacement into a linear displacement. An electric pilot pressure control valve whose force is changed is provided, and the pressure output by the electric pilot pressure control valve is given to a pressure adjusting piston of the pilot pressure control valve so as to move it.

[0005]

According to the electric motor operating pressure control valve having such a configuration, the spring force of the first pressure adjusting spring of the pilot pressure control valve for obtaining the set pressure moves according to the pressure output by the electric pilot pressure control valve. Changed by the pressure regulating piston,
A set pressure corresponding to the rotation of the electric motor can be obtained. Then, even if the pressure applied from the electric pilot pressure control valve is small, the pressure adjusting piston can move so as to bend the first pressure adjusting spring by generating a large force corresponding to the product of this pressure and the pressure receiving area. Therefore, the pressure output from the electric pilot relief valve can be reduced, and the spring force of the second pressure regulating spring is reduced. Therefore, the frictional force in the screw mechanism is reduced, and its wear is frequently caused by changing the set pressure. Regardless of the size, it is kept small and durability is improved.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a main valve, which has a main valve body 6 housed in a sleeve 5 installed in a first main body 4 having an inlet passage 2 and an outlet passage 3. The main valve body 6 moves to the right from the state of FIG. 1 in which the inlet and outlet passages 2 and 3 are closed, and the through holes 7, 8, 9 and 10 of the sleeve 5 and the intermediate groove 11 of the first main body 4. It is slidable in the sleeve 5 in the axial direction so as to be opened through the inlet and outlet passages 2 and 3 via. The left end of the sleeve 5 is closed by a plug 13 held by a lid 12 to form a pressure chamber 14 with the main valve body 6, and the main valve body 6 is introduced into the pressure chamber 14 through a through hole 15. It receives pressure from the passage 2 and is pressed in the opening direction. A safety valve 1 held by a lid 17 at the right end of the sleeve 5.
8 is provided with a valve seat body 19 and a spring 20 is provided between the valve seat body 19 and the main valve body 6.
To form a pilot chamber 21. The pilot chamber 21 includes a first main body 9 and a second main body 2 mounted on the first main body 9.
2 through the through holes 23, 24, 25.
The main valve body 6 is communicated with the inlet passage 2 via 6 and is pressed by the pressing force of the spring 20 and the pressure of the pilot chamber 21 in a direction to close the inlet and outlet passages 2 and 3. ..

Reference numeral 27 denotes a pilot relief valve which serves as a pilot pressure control valve for controlling the pressure in the pilot chamber 21, and has an inlet chamber 28, a valve seat 29, an outlet chamber 30, and an outlet chamber 30 through which the through hole 24 communicates with the second main body 22. It has a poppet-like valve element 33 that is seated on the valve seat 29 so as to close the inlet and outlet chambers 28 and 30 by receiving the spring force of the first pressure regulating springs 31 and 32 provided. A cylinder member 35 having a cylinder hole 34 communicating with the outlet chamber 30 is attached to the second main body 22, and a pressure adjusting piston 37 supporting a spring receiver 36 for receiving the first pressure adjusting springs 31 and 32 is attached to the cylinder hole 34. Is slidably accommodated, and a pressure adjusting chamber 38 is formed on the side of the pressure adjusting piston 37 opposite to the spring receiver 36. Reference numeral 39 is an adjusting screw that comes into contact with the pressure adjusting piston 37 and adjusts the minimum value of the spring force of the first pressure adjusting springs 31 and 32, and is screwed to the cylinder member 35 so as to be able to move forward and backward.

Reference numeral 40 is a third body mounted on the second body 22 and provided with an electric pilot relief valve 41 which serves as an electric pilot pressure control valve. Reference numeral 42 denotes a pressure reducing valve, which is connected to the inlet chamber 43 from the first main body 4 to the second main body 22 and the third main body 4.
The fluid in the inlet passage 2 is guided from the through hole 23 by the through hole 44 provided to the main body 40, and the pressure reducing valve 42 is connected to the throttle 4
5, the pressure of the outlet chamber 48 communicating with the inlet chamber 47 of the electric pilot relief valve 41 is reduced to a pressure corresponding to the spring force of the pressure adjusting spring 50 provided in the spring chamber 49. ing.

The electric pilot relief valve 41 is provided with an inlet chamber 47, a valve seat 51 and an outlet chamber 52. The spring force of a second pressure adjusting spring 53 provided in the outlet chamber 52 causes the inlet and outlet chambers 4 to 4
It has a poppet-shaped valve body 54 which is seated on the valve seat 51 so as to close the space between the valves 7 and 52. Reference numeral 55 is a support table attached to the third main body 40, and an electric motor 56 with a speed reducer that rotates in the forward and reverse directions is attached. Reference numeral 57 denotes a sleeve with an internal thread 59, which is connected to the output shaft 58 of the electric motor 56 so as to rotate integrally therewith, and includes a pair of thrust bearings 60A and 60B and a retaining ring 61.
It is attached to the support base 55 so as not to move in the axial direction by A and 61B. 62 is a spring receiver for receiving the second pressure adjusting spring 53 and is provided with a pin 64 that engages with a rotation stop groove 63 provided in the support base 55 to prevent rotation, and is also screwed into the female screw 59 of the sleeve 57. A screw 65 is provided so that when the sleeve 57 rotates, the spring receiver 62 can advance and retreat in the axial direction so as to change the spring force of the second pressure adjusting spring 53, thereby converting the rotational displacement into a linear displacement. Mechanism 6
6 are configured. In addition, 67 and 68 are limit switches operated by the pin 64, and detect that the spring receiver 62 has reached the movement end. The inlet chamber 47 of the electric pilot relief valve 41 communicates with the pressure adjusting chamber 38 of the pilot relief valve 27 through a series of through holes 69. The outlet chamber 52 of the electric pilot relief valve 41, the spring chamber 49 of the pressure reducing valve 42, and the outlet chamber 30 of the pilot relief valve 27 are connected to the outlet passage 3 by a series of drain holes 70.

Next, the operation of this structure will be described. Figure 1
In this state, the spring receiver 62 of the electric pilot relief valve 41 is at the right end of the movement and the second pressure adjusting spring 53
Has the lowest spring force. In response to this spring force, a minimum pressure is generated in the inlet chamber 47 as a result of the valve body 54 opening and flowing from the inlet chamber 47 to the outlet chamber 52.
The pressure in the inlet chamber 47 is introduced into the pressure adjusting chamber 38 of the pilot relief valve 27, but the pressure adjusting piston 37 is kept on the right side by the first pressure adjusting springs 31 and 32 so that the first pressure adjusting springs 31 and 32 receive the pressure adjusting piston 37. The spring force is in the lowest state. In the pilot relief valve 27, the valve body 33 is opened to flow from the inlet chamber 28 to the outlet chamber 30. As a result, in the inlet chamber 28, the pilot relief valve corresponding to the spring force of the first pressure regulating springs 31, 32 is provided. The lowest pressure at 27 is created and introduced into the pilot chamber 21 of the main valve 1. Therefore, the pressure in the inlet passage 2 that is guided to the pressure chamber 14 and presses the main valve body 6 in the opening direction is equal to the pressure in the pilot chamber 21 in which the acting force in the opening direction presses the main valve body 6 in the closing direction. If it becomes larger than the pressing force by the spring force of the spring 20 and the spring force of the spring 20, the main valve body 6 is opened, and if it becomes smaller, the main valve body 6 is closed and a pressure corresponding to the pressure of the pilot chamber 21 is obtained. The pressure is set according to the minimum spring force of the first pressure adjusting springs 31, 32.

From this state, when the electric motor 56 is rotated by a predetermined amount to the left and the spring receiver 62 is moved leftward by a predetermined amount, the second pressure adjusting spring 53 flexes in response to this and the spring force thereof increases. Therefore, the pressure in the inlet chamber 47 of the electric pilot pressure control valve 41 is increased by the amount of increase in the spring force of the second pressure adjusting spring 53, and this pressure is guided to the pressure adjusting chamber 38, so that the pressure adjusting piston 37 is moved. The first pressure adjusting springs 31 and 32 are bent and leftward until they are in agreement with the spring force. As a result, the spring force of the first pressure regulating springs 31, 32 increases, and as a result, the pressure in the inlet chamber 28 of the pilot relief valve 27 increases by the amount of increase in the spring force, and this pressure is introduced into the pilot chamber 21. The valve 1 is set to a pressure higher by this increase amount, and the inlet passage 2 is increased in pressure by the pressure increase of the pilot chamber 21.
In this way, if the electric motor 56 is further rotated in one direction and the spring bearing 62 is moved leftward, the pressure in the inlet passage 2 of the main valve 1 is correspondingly increased, and conversely the electric motor 56 is rotated in the other direction. When the spring receiver 62 is moved to the right, the pressure in the inlet passage 2 becomes lower accordingly, and the pressure in the inlet passage 2 is set by the rotation of the electric motor 57.

Here, the pressure receiving surface area of the valve element 33 of the pilot relief valve 27 is generally small, whereas the pressure receiving area of the pressure adjusting piston 37 that receives the pressure of the pressure adjusting chamber 38 can be made sufficiently large, so that the electric pilot relief is provided. Valve 4
In this embodiment, the pilot pressure control valve 27 has a maximum of 7 by obtaining a small pressure of 10 kg / cm ² at maximum.
The spring force of the first pressure adjusting springs 31 and 32 can be determined by moving the pressure adjusting piston 37 so as to set a high pressure of 00 kg / cm ² . Since the pressure obtained by the electric pilot relief valve 41 can be reduced in this manner, the spring force of the second pressure adjusting spring 53 is reduced, and therefore the male screw 65 and the screw sleeve 57 of the spring receiver 62 that are screwed together are fitted. Screw 59
The frictional force at the motor is reduced, the wear is reduced, the durability is increased, and the motor 5 can be used satisfactorily for a long time.
6 can also be made small with a small torque.

Here, the pressure reducing valve 42 uses a spring force of the pressure adjusting spring 50 so that the maximum pressure obtained by the electric pilot relief valve 41 of 10 kg / cm ² or a pressure slightly higher than the maximum pressure is obtained in the outlet chamber 48. Since the pressure reducing valve 42 reduces the pressure of the fluid introduced from the inlet passage 2 to the electric pilot relief valve 41 in this way, the inlet passage 2 is
Even if the pressure is as high as 0 kg / cm ² , the electric pilot relief valve 41 has a maximum flow rate of 10 kg / cm at a small flow rate.
^A pressure as low as ² can be obtained, and the electric pilot relief valve 41 can be made compact. However, in this embodiment, the through hole 44 is connected to the through hole 23 to guide the fluid in the inlet passage 2 to the electric pilot relief valve 41. However, if an appropriate low pressure source can be secured, the through hole 44 is used. It may be connected to this low pressure source without being connected to the through hole 23, and in this case, the pressure reducing valve is so arranged that the fluid from the low pressure source is directly led to the inlet chamber 47 via the throttle 45. It is also possible to omit 42. The safety valve 18 is the pilot pressure control valve 27.
Does not open, and when the pressure in the inlet passage 2 reaches a permissible value and opens, the main valve body 6 is opened to prevent the pressure in the inlet passage 2 from rising above the permissible value.

Although relief valves such as 27 and 41 are used as the pilot pressure control valve and the electric pilot pressure control valve, pressure reducing valves may be used. In the screw mechanism 66, the female screw 59 is provided on the sleeve 57 and the screw 65 is provided on the spring receiver 62. However, a female screw may be provided on the spring receiver 62, and a male screw to be screwed onto the screw sleeve 57 may be provided. Alternatively, the screw mechanism 66 as shown in FIG. 2 may be used. That is, 59A is a screw for mounting on the third body 40, and a male screw 65A is screwed into the male screw 65A. The male screw 65A has a recessed hole 65 into which the output shaft 58 of the electric motor 56 is fitted.
B is provided, and the groove 65C is provided in the concave hole 65B in the axial direction.
The pin 58A provided on the output shaft 58 is engaged with the screw 6
5A and the output shaft 58 are connected so as to rotate integrally while allowing relative movement in the axial direction. And the spring bearing 62 is the steel ball 6
2A is in contact with the screw 65A, whereby the spring receiver 62 is axially moved via the screw 65A in accordance with the rotation of the electric motor 56, and the spring force of the second pressure adjusting spring 53 is adjusted. It is.

[0015]

As described above, according to the configuration of the present invention, the spring force of the first pressure adjusting spring in the pilot pressure control valve for controlling the pressure output from the electric pilot pressure control valve to control the pressure in the pilot chamber of the main valve is controlled. In order to apply the pressure-regulating piston to change, the electric pilot pressure control valve only needs to output a small pressure. Therefore, the spring force of the second pressure-adjusting spring is reduced, the friction in the screw mechanism is reduced, and the wear is reduced. The durability is increased and the durability is increased, and the motor can be favorably used for a long period of time, and a small electric motor with a small torque can be used. Furthermore, if the pressure receiving area of the main valve body that receives the pressure in the pilot chamber is made much larger than the pressure receiving area that receives the pressure from the inlet passage, even if an extremely high pressure is to be obtained in the inlet passage, the electric type It is possible to use the pilot pressure control valve to control the pressure in the pilot chamber to reduce the spring force of the pressure regulating spring, but in this case it is very large on both pressure receiving surfaces of the main valve body as described above. Due to the pressure receiving area ratio, the main valve becomes extremely large and the valve shape becomes large. However, according to the present invention, the main valve does not become unnecessarily large and a compact valve can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing another embodiment of the screw mechanism.

[Explanation of symbols]

 1 main valve 2 inlet passage 3 outlet passage 6 main valve body 21 pilot chamber 26 throttle 27 pilot pressure control valve 31, 32 first pressure adjusting spring 37 pressure adjusting piston 41 electric pilot pressure control valve 53 second pressure adjusting spring 56 electric motor 66 screw mechanism

Claims (1)

[Claims] 1. A main valve having a main valve body which is movable so as to open and close between an inlet and an outlet passage, and which receives a pressure from the inlet passage in an opening direction and a pressure controlled by a pilot chamber in a closing direction. And a pilot pressure control valve for controlling the pressure in the pilot chamber according to the spring force of the first pressure regulating spring. The pilot pressure control valve changes the amount of deflection of the first pressure regulating spring by movement to change the spring force. The pressure adjusting piston is provided to output a pressure according to the spring force of the second pressure adjusting spring, and at the same time, the second pressure adjusting spring changes the deflection amount by the rotation of the electric motor through the screw mechanism that converts the rotational displacement into the linear displacement. Equipped with an electric pilot pressure control valve whose spring force can be changed,
An electric motor operating pressure control valve, wherein the pressure output from the electric pilot pressure control valve is applied to a pressure adjusting piston of the pilot pressure control valve so as to move the piston.