JP2538764Y2 - Pressure control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a pressure control valve suitable for use in, for example, attitude control of a vehicle, and in particular, an electromagnetic proportional pressure control for controlling pressure in proportion to current. It relates to a control valve.

(Prior Art) In recent years, there is a tendency that a high level of comfort is also required of a vehicle. For example, vehicle height adjustment and posture control of a vehicle body during cornering and braking are performed.

Such various controls are often performed using a hydraulic pressure such as a hydraulic pressure. In this case, a pressure control valve for generating a hydraulic pressure proportional to a current value or a voltage value to the solenoid is used.

Conventionally, as a pressure control valve of this type, for example,
The one described in JP-A-58-156784 is known.

However, such a conventional pressure control valve has a problem that the control hydraulic pressure fluctuates due to the influence of the surge pressure.

In order to solve this problem, the present applicant has proposed a pressure control valve disclosed in Japanese Utility Model Application No. 63-69170 (Japanese Utility Model Application Publication No. 5-44626).

In this conventional pressure control valve, a back pressure preventing orifice and a buffering orifice are provided in a sub-drain passage communicating between the low-pressure chambers defined on both end surfaces of the valve spool and the main drain passage. .

In other words, this conventional pressure control valve damps surge pressure generated on the main drain passage side, which repeatedly communicates and shuts off with the control pressure port, with the back pressure prevention orifice provided on the sub drain passage, and surges the surge pressure toward the low pressure chamber side. The pressure is prevented from being transmitted, so that the fluctuation of the control hydraulic pressure can be prevented.

Further, the flow of the pressure oil during the stroke of the valve spool is damped by the buffer orifice, thereby preventing oscillation.

(Problem to be Solved by the Invention) As described above, in the device of the prior application filed by the present applicant, the control fluid pressure is stable without being affected by the surge pressure.
Although this is an excellent one having an effect of preventing oscillation of the valve spool, it has problems to be solved as described below.

That is, in the pressure control valve of the prior application, the orifice for buffering and the orifice for preventing back pressure are arranged in parallel with one low-pressure chamber and in series with the other low-pressure chamber. The flow rate to the buffer orifice varies depending on the sliding direction of the valve spool, and a difference occurs in the damping effect. Therefore, in particular, when air is mixed in the pressurized oil, there is a problem that the difference in the degree of this effect increases and the valve spool oscillates.

And in order to avoid such problems,
The air must be carefully vented, and in this case, there is a problem that the production is troublesome.

In addition, when the diameter of the valve spool is different between the one low-pressure chamber and the other low-pressure chamber as in the embodiment of the prior application, the amount of change in the volume in both low-pressure chambers is different. There is a problem that the flow rate of the pressure oil flowing through the orifice differs between when the control hydraulic pressure is increased and when the control hydraulic pressure is reduced, and the difference in the degree of the damping effect increases.

The present invention has been made in consideration of such a problem, and can solve the problem that the conventional control fluid pressure is affected by the surge pressure, and further, can prevent the oscillation of the valve spool by the damping effect. It is an object of the present invention to provide a pressure control valve which can provide a constant damping effect regardless of the sliding direction of the spool even if the diameters of both ends of the spool are different.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the invention according to claim 1,
A control pressure port slidably provided in a valve hole formed in the valve body, and the control pressure port opened in the valve hole is connected to one of a supply port and a main drain passage also opened in the valve hole. A valve spool capable of controlling the control hydraulic pressure, control means for pressing the valve spool in the control hydraulic pressure increasing direction, reaction force means for pressing the valve spool in the control hydraulic pressure reducing direction, and the valve spool A direct-acting pressure control valve having two low-pressure chambers respectively formed facing both end faces of the communication passage, and a communication passage formed in the valve body by communicating the low-pressure chambers with each other; A buffer orifice provided on the way and a first sub-drain passage formed in the valve body and a second sub-drain passage formed in the valve body by communicating each of the low-pressure chambers with the main drain passage.
Sub-drain passage, a first back pressure preventing orifice provided in the middle of the first sub-drain passage, and a second back pressure preventing orifice provided in the middle of the second sub-drain passage And provided.

According to the invention of claim 2, the control port is slidably provided in a main valve hole formed in the valve body, and is driven based on receiving pilot control hydraulic pressure to drive the control port between the main supply port and the main drain passage. A main spool configured to control the control hydraulic pressure by being connected to any one of them, and a pilot control pressure port slidably provided in a pilot valve hole formed in the valve body and opened to the pilot valve hole. Similarly, a pilot spool connected to one of a pilot supply port and a pilot drain port opened in a pilot valve hole and capable of controlling a pilot control hydraulic pressure, and press-controlling the pilot spool in the pilot control hydraulic pressure increasing direction. A pilot control means, and a pilot control hydraulic pressure reducing direction for the pilot spool. And pilot reaction force means for pressing,
A pilot-type pressure control valve having two low-pressure chambers respectively formed facing both end surfaces of the pilot spool; and a communication passage formed in a valve body for communicating the two low-pressure chambers with each other. A buffer orifice provided in the middle of the passage, a first sub-drain passage and a second sub-drain passage formed in the valve body by connecting each of the low-pressure chambers to the main drain passage;
A first back pressure preventing orifice provided in the middle of the sub-drain passage and a second back pressure preventing orifice provided in the middle of the second sub-drain passage.

(Operation) In the low-pressure control valve of the present invention, first and second orifices for preventing back pressure are provided in the middle of the first and second sub-drain passages that communicate each low-pressure chamber with the main drain passage. Therefore, the surge pressure generated in the working fluid from the main drain passage is damped and cut off by the flow path resistance of the back pressure preventing orifice, so that the control fluid pressure is stabilized.

In the present invention, since the two low-pressure chambers communicate with each other through a communication passage, and a buffer orifice is provided in this communication passage, the valve spool or the pilot spool slides, and when the volume fluctuation occurs in both the low-pressure chambers, The hydraulic fluid in the low pressure chamber flows into the other low pressure chamber through the communication path and the buffer orifice in the middle thereof, and at this time, the oscillation of the valve spool occurs due to the flow path resistance generated when the hydraulic fluid communicates with the buffer orifice. Is prevented.

In this case, the buffer orifice and the first back pressure preventing orifice are provided in parallel with one low pressure chamber, and the buffer orifice and the second back pressure preventing orifice are provided with the other low pressure chamber. Since they are provided in parallel, the flow rate to the buffer orifice can be adjusted by the amount of throttle of the first and second back pressure preventing orifices.

Therefore, when the valve spool (pilot spool) is formed to have different diameters at both ends and there is a difference in the volume change between the two low-pressure chambers depending on the sliding direction of the spool, the first and second valve spools are different.
Of the back pressure preventing orifice, that is, the opening degree of the back pressure preventing orifice on the side of the low pressure chamber having the larger volume change is increased to reduce the flow rate to the buffer orifice (communication passage). Can be constant.

Thus, the valve spool (pilot spool)
Even if there is a diameter difference between both ends of the spool, regardless of whether the sliding direction of the valve spool (pilot spool) is in the pressure increasing direction or the pressure decreasing direction, the flow rate in the communication passage when the spool slides is kept constant to reduce the damping effect. Can be constant.

As described above, in the pressure control valve of the present invention, since the damping effect in the control fluid pressure (pilot control fluid pressure) increasing direction and the control fluid pressure (pilot control fluid pressure) decreasing direction can be made uniform, Even when air is mixed in the oil, the damping effect does not greatly change depending on the sliding direction, so that the oscillation phenomenon based on the difference between the two damping effects is prevented.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

 First, the configuration of the embodiment will be described.

FIG. 1 is a sectional view showing a pressure control valve according to a first embodiment which is an embodiment of the present invention according to claim 2;
Reference numeral 22 denotes a valve body. In the valve body 22, a main valve hole 21a and a pilot valve hole 21b are formed coaxially, and a main spool 23 and a pilot spool 24 are slidably provided in the holes 21a and 21b, respectively.

The pilot spool 24 has a large-diameter portion 25 formed at one end thereof, and the large-diameter portion 25 forms an annular feedback chamber (pilot reaction force means) 26 together with the pilot spool 24.
A large-diameter portion 25 side end surface defines a low-pressure chamber 27 filled with pressurized oil, and a plunger 29 of a solenoid (pilot control means) 28 abuts the end surface. 29 is urged toward the pilot spool 24 by a spring (not shown).

In the vicinity of the center of the pilot spool 24, an annular pilot control chamber 30 is defined. The pilot control chamber 30 is connected to a pilot control pressure port 21d opened toward the pilot control chamber 30 through an oil passage. While communicating with a pilot pressure chamber 58 to be described later via 60, it communicates with the feedback chamber 26 via an oil passage 31 formed inside the pilot spool 24.

A low-pressure chamber 32 filled with pressure oil is defined on the end surface of the pilot spool 24 on the main spool 23 side. A spring (pilot reaction force means) 33 for urging the pilot spool 24 toward the solenoid 28 is formed in the low-pressure chamber 32. Is inserted.

That is, the pilot spool 24 receives the respective biasing forces of the springs for biasing the springs 33 and the plungers 29 on both end surfaces, and stops at a position where the biasing forces are balanced, and when the solenoid 28 is driven, the plunger 29 And the feedback force obtained in the feedback chamber 26 is in a balanced position, and the pilot spool 24 stops.

A valve body is provided around the pilot spool 24.
An annular pilot supply port 34 and a pilot drain port 35 formed on the 22 side are opened, and the pilot spool 24 is
When the solenoid 28 is driven and slid rightward in the figure from the set position, the pilot supply port 34 is opened, and the solenoid 28 is stopped. When sliding to the left from the set position, the pilot drain port
Open 35.

Pressure oil pressurized by a tank 36 from a reservoir tank 37 is guided to the pilot supply port 34 via a pipe 38, an oil passage 39, and an oil passage 40, and the pilot drain port 35 is an oil as a main drain passage. The reservoir 41 communicates with the reservoir tank 37 via a passage 41, an oil passage 42, an oil passage 43, and a pipe 44.

The oil passage 42 is communicated with the low-pressure chamber 27 by an oil passage (first sub-drain passage) 48 in which a (first) back pressure preventing orifice 47 is provided on the way, and An oil passage (second sub-drain passage) 46 provided with a (second) back pressure preventing orifice 45 communicates with the low pressure chamber 32.

The low-pressure chamber 27 and the low-pressure chamber 32 communicate with each other through a communication path 202 provided with a buffer orifice 201 in the middle.

On the other hand, near the center of the main spool 23, the main control room
51 is defined, and the main control chamber 51 is provided with a cylinder port.
It communicates with a hydraulic cylinder CYL (not shown) via a 52 (main control pressure port) and a pipe 53.

A main feedback chamber 54 is defined at an end of the main spool 23 on the pilot spool 24 side, and the main feedback chamber 54 urges the main spool 23 therein in a direction opposite to the pilot spool 24 side. Spring 55 is inserted and the main spool 23
It communicates with the main control chamber 51 via an oil passage 56 formed inside. The oil passage 56 is provided with a throttle 57.

The main feedback chamber 54 of the main spool 23
A pilot pressure chamber 58 is defined on the opposite end face, and a spring 59 for urging the main spool 23 toward the pilot spool 24 is inserted in the pilot pressure chamber 58.

That is, the main spool 23 has springs 55,5 on both end surfaces.
It receives the urging force of 9, and stops at the position where the urging force is balanced.

The pilot pressure chamber 58 and the pilot control chamber 30 communicate with each other through an oil passage 60.

In addition, an annular main supply port 61 and a main drain port 62 formed in the valve body 22 are opened around the main spool 23, and the biasing forces of the respective springs are balanced so that the main spool 23 stops. The main spool 23 closes both the main supply port 61 and the main drain port 62 (hereinafter, referred to as stabilization).

The main supply port 61 communicates with the oil passage 39 for guiding the pressure oil from the pump 36, and the main drain port 62 has an oil passage 43 that communicates with the reservoir tank 37.

 Next, the operation of the embodiment will be described.

When a predetermined current is applied to the solenoid 28, an electromagnetic force corresponding to the current is generated in the solenoid 28, and the plunger 29 presses the pilot spool 24 rightward in the drawing to slide.

The sliding of the pilot spool 24 allows the pilot control chamber 30 and the pilot supply port 34 to communicate with each other.
The pressure oil pressurized by 36 is guided to pilot control chamber 30, so that the pressure in feedback chamber 26 increases through pilot control chamber 30 and oil passage 31. At this time, the pressure in the pilot control chamber 30 is
Since the main spool 23 is guided to 58, the main spool 23 slides toward the pilot spool 24 and the main supply port 61 communicates with the main control chamber 51, so that the pressure oil pressurized by the pump 36 is supplied to the main control chamber 51. Guided, main control room 51 and oil passage
Via 56, the pressure in the main feedback chamber 54 increases.

At this time, the force applied to the pilot spool 24 is expressed by the following equation, where A is the cross-sectional area of the feedback chamber 26 in the axial direction of the pilot spool 24 (pressure receiving area of the feedback chamber).

F _S = A · P _F + k _X, where P _F : pressure in feedback chamber 26 k _X : urging force of spring 33 That is, when the electromagnetic force F _S and the force on the right side of the equation become equal, it acts on pilot spool 24. The piloting spool 24 is settled by the balance of the forces to be performed. In this case, the electromagnetic force F _S from it is proportional to the current i, as described above, the pilot control pressure P _P is guided to the pilot pressure chamber 58 is proportional to the current i of the solenoid 28. And the pilot control hydraulic pressure
Load of the pressing force and the pressing force is equal based on the pressure of the main feedback chamber 54 main spool 23 is settled pressure control valve 21 based on the P _P, i.e. the main control solution in accordance with the electromagnetic force F _S to the hydraulic cylinder CYL Pressure is applied. In this case, the biasing force of the spring (not shown) in the solenoid 28 is included in the electromagnetic force F _S.

On the other hand, when the current of the solenoid 28 is reduced, the electromagnetic force F _S
Therefore, the balance of the pilot spool 24 is lost, and the pilot spool 24 slides toward the solenoid 28 (to the left in the drawing).

The sliding of the pilot spool 24 releases the pressure oil in the pilot control chamber 30 to the reservoir tank 37 through the pilot drain port 35, so that the pilot control hydraulic pressure in the pilot control chamber 30 decreases and the pilot pressure chamber 58 The pressure also decreases, the balance of the main spool 23 is lost, and the pressure oil in the main control chamber 51 is released to the reservoir tank 37 via the main drain port 62.

That is, the main control hydraulic pressure supplied to the hydraulic cylinder CYL decreases. Then, when the above expression is satisfied with respect to the reduced electromagnetic force F _S , the pilot spool 24 is settled, and the pilot control hydraulic pressures in the pilot control chamber 30 and the pilot pressure chamber 58 correspond to the electromagnetic force. Therefore,
The main control hydraulic pressure to the cylinder decreases in response to the pilot control hydraulic pressure.

As described above, when a predetermined current is applied to the solenoid 28, a relatively large main control fluid pressure (for example, 30 kg / cm ² or more) is generated in the cylinder port 52, and the main control fluid pressure is reduced. Sometimes high pressure oil is stored in the reservoir tank
The pressure oil flowing through the oil passage 43 has a large flow rate instantaneously and generates a surge pressure because it is opened to the oil passage 37. The oil passage 48 that communicates the oil passage 43 with the low-pressure chambers 27 and 32, respectively. , 46 are respectively provided with orifices 45, 47 for preventing back pressure, so that the surge pressure generated in the oil passage 43 is reduced by the orifices 45, 4
The damping is performed by the flow path resistance of 7, and the influence on the pilot spool 24 side is cut off. Therefore, the fluctuation of the pilot control hydraulic pressure can be prevented. This means that the stability of the main control hydraulic pressure is greatly improved.

Conventionally, there has been a case where the drain flow rate on the main spool 23 side is set to be small in consideration of the above-mentioned problem due to the generation of the surge pressure. Since the prevention orifices 45 and 47 are provided, a large flow rate can be drained without worrying about the influence of surge pressure.
When the main control hydraulic pressure is reduced, the target hydraulic pressure can be made to match quickly, and the response speed can be increased.

Further, in this embodiment, as described above, since the low-pressure chamber 27 and the low-pressure chamber 32 are communicated with each other through the communication path 202 through the buffer orifice 201, the pilot spool 24 slides in the pressure increasing or decreasing direction. Then, the hydraulic fluids in both chambers 27 and 32 flow through each other through the communication path 202, and are damped by the flow path resistance of the buffer orifice 201.

By the way, in the present embodiment, a large diameter portion 25 is formed at the left end of the pilot spool 24 in the drawing, and the diameter is different at both ends. 27 and 32 have different volume change amounts. Therefore, regardless of the sliding direction of the pilot spool 24, the throttle amounts of the back pressure preventing orifices 45 and 47 are slightly different so that a constant flow rate can be obtained in the communication passage 202. That is, when the pilot spool 24 slides in a direction to sandwich the large-diameter low-pressure chamber 27, a part of the flow rate flowing out of the low-pressure chamber 27 is released to the oil passage 48 side to prevent back pressure. The opening of the orifice 47 is made larger than the orifice 45 for preventing back pressure.

As described above, even if the pilot spool 24 slides in any of the axial directions by changing the throttle amounts of the back pressure prevention orifices 45 and 47, a fixed amount of pressure oil flows through the communication passage 202. Since the damping effect of the buffer orifice 201 in the pressure increasing direction and the pressure reducing direction by the buffer orifice 201 becomes uniform, even if air is mixed in the hydraulic fluid, the damping effect does not change. No oscillation phenomenon is caused due to the difference in the effects.

In the first embodiment, the main spool 23 for changing the control hydraulic pressure and the pilot spool 24 for changing the pilot pressure are used.
A case where the present invention is applied to a so-called pilot-type pressure control valve provided with the following is shown. Next, as a second embodiment, an embodiment of a direct acting pressure control valve according to the invention described in claim 1 will be described. This will be described with reference to FIG. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this direct acting type pressure control valve, the pressure oil from the pump 36 faces around the valve spool 75 housed in the valve hole 21c formed in the valve body 74 via the pipe 72 and the oil passage 73. It is led to an open supply port and 76. A plunger of a solenoid (control means) 28 is provided at one end of the valve spool 75.
A large diameter portion 77 with which the abutment 29 abuts is formed, and the large diameter portion 77 defines a low pressure chamber 78 filled with pressure oil on the solenoid 28 side,
A feedback chamber (reaction means) 79 is defined on the valve body 74 side. The low pressure chamber 78 is connected to an oil passage (first sub-drain passage) 83 by a first back pressure preventing orifice.
The oil is led to an oil passage (main drain passage) 85 for guiding the drain pressure oil of the pressure control valve via 84.

At the other end of the oil passage 73, a spring (reaction means) 80 for urging the valve spool 75 toward the solenoid 28 is inserted, and a low-pressure chamber 81 filled with pressure oil is defined. The low-pressure chamber 81 is provided with an oil passage (second sub-drain passage) 82
As a result, the oil is guided to the oil passage 85 through the second back pressure preventing orifice 86. Further, the low-pressure chamber 78 and the low-pressure chamber 81 are communicated with each other by a communication passage 202 provided with a buffer orifice 201.

Here, when the solenoid 28 is energized, the generated electromagnetic force presses the valve spool 75, and pressure oil from the supply port 76 is introduced into the control chamber 87 defined at the center of the spool 75, and the valve spool 75 It is guided to a feedback chamber 79 via an oil passage 88 formed inside 75.

Accordingly, the control hydraulic pressure of the cylinder port 89 (control pressure port) increases, and the feedback chamber increases with the increase of the control hydraulic pressure.
Since the pressure of the valve 79 also increases, the valve spool 75 slides toward the solenoid 28 (left side in the figure), and the pressing force determined by the pressure of the feedback chamber 79 based on the control hydraulic pressure and the pressure receiving area of the feedback chamber 79 is increased. When the pressure coincides with the pressing force, the valve spool 75 is settled, and the control hydraulic pressure according to the electromagnetic force is supplied to the load such as the hydraulic cylinder CYL via the pipe 90.

On the other hand, at the time of pressure reduction, by reducing the current value of the solenoid 28, the balance of the pressing force applied to the oil passage 73 is lost, and the valve spool 75 slides toward the solenoid 28 (left side in the figure), and the oil passage 85 is opened. The pressurized oil in the control chamber 87 is guided to the drain port 91 and is opened to the reservoir tank 37 by a pipe 92 connected to the oil passage 85.

At this time, even if a surge pressure is generated in the oil passage 85, the oil pressure is damped by the back pressure preventing orifices 84 and 86.
The same operation and effect as the embodiment can be obtained.

Then, since the control hydraulic pressure is released to the reservoir tank 37, the pressure in the control chamber 87 and the feedback chamber 79 decreases,
When the valve spool 75 slides toward the low pressure chamber 81 and settles,
A control hydraulic pressure is generated according to the reduced electromagnetic force.

When the pilot spool 75 slides in the pressure increasing or decreasing direction, the pressure oil in both the chambers 78 and 81 flows through the communication passage 202 and is damped by the flow path resistance of the buffer orifice 201. Therefore, the same function and effect as those of the first embodiment can be obtained.

The embodiment of the present invention has been described in detail with reference to the drawings.
The specific configuration is not limited to this embodiment, and even if there is a design change or the like within a range not departing from the gist of the present invention, it is included in the present invention.

For example, in the embodiment, the solenoid is used as the control means, but other means such as using a hydraulic means or using an actuator such as a motor can be applied.

(Effects of the Invention) As described above, in the pressure control valve of the present invention, each of the low-pressure chambers provided at both ends of the spool communicates with the first and second sub-drain passages that communicate with the main drain passage. Since the first and second back-pressure buffer orifices are provided, and the buffer orifice is provided in the communication passage connecting the two low-pressure chambers, it is possible to prevent the control fluid pressure from fluctuating due to the generation of surge pressure, and When the valve spool (Claim 1) or the pilot spool (Claim 2) slides, oscillation of the valve spool can be prevented even if air is mixed in, due to the damping effect of the liquid in the low-pressure chamber flowing through the buffer orifice. In the present invention, in particular, in the present invention, by providing orifices for preventing back pressure in each sub-drain passage, it is assumed that the orifice is provided in the sliding direction of the valve spool. Even if the volume change of both low pressure chambers is different,
By adjusting the flow rate to the sub-drain side, it is possible to obtain an effect that the flow rate at the buffer orifice of the communication path is constant and the damping effect can be made uniform.

The effect of preventing oscillation even when air is mixed in this way eliminates the need to carefully perform air bleeding at the time of manufacturing, and provides a synergistic effect of simplifying manufacturing.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a pressure control valve according to a first embodiment of the present invention;
FIG. 2 is a sectional view showing a pressure control valve according to a second embodiment of the present invention. 21a: Main valve hole 21b: Pilot valve hole 21c: Valve hole 21d: Pilot control pressure port 22: Valve body 23: Main spool 24: Pilot spool 26: Feedback chamber (pilot reaction force means) 27 Low pressure chamber 28 Solenoid (pilot control means) 30 Pilot control chamber 32 Low pressure chamber 33 Spring (pilot reaction force means) 34 Pilot supply port 35 Pilot drain port 41, 42 , 43 ... oil passage (main drain passage) 45 ... (second) back pressure preventing orifice 46 ... oil passage (second sub-drain passage) 47 ... (first) back pressure preventing orifice 48 Oil passage (first sub-drain passage) 52 Cylinder port (main control pressure port) 61 Main supply port 78 Low pressure chamber 75 Valve spool 76 Supply port 79 ... feedback chamber (reaction means) 80 ... spring (reaction means) 81 ... low-pressure chamber 82 ... oil passage (second sub-drain passage) 83 ... oil passage (first sub-drain passage) 84 ... ... (first) back pressure preventing orifice 85 ... oil passage (main drain passage) 86 ... (second) back pressure preventing orifice 89 ... cylinder port (control pressure port) 201 ... buffer orifice 202 ...

Claims (2)

(57) [Scope of request for utility model registration] 1. A control pressure port slidably provided in a valve hole formed in a valve body and opened in the valve hole, and connected to one of a supply port and a main drain passage also opened in the valve hole. A valve spool capable of controlling the control hydraulic pressure of the control pressure port, a control means for pressing the valve spool in the control hydraulic pressure increasing direction, and a reaction force means for pressing the valve spool in the control hydraulic pressure reducing direction A direct-acting pressure control valve comprising: two low-pressure chambers respectively formed on both end surfaces of the valve spool; and a communication passage formed in the valve body by communicating the two low-pressure chambers with each other. A buffer orifice provided in the communication passage; a first sub-drain passage formed in the valve body by connecting each of the low-pressure chambers to the main drain passage; A drain passage, a first back pressure preventing orifice provided in the middle of the first sub-drain passage, and a second back pressure preventing orifice provided in the middle of the second sub-drain passage; A pressure control valve, comprising: 2. A control valve, which is slidably provided in a main valve hole formed in a valve body and is driven based on receiving a pilot control hydraulic pressure to set a control port to one of a main supply port and a main drain passage. A main spool configured to be connected to control the control hydraulic pressure, and a pilot control pressure port slidably provided in a pilot valve hole formed in the valve body and opened in the pilot valve hole. A pilot spool which can be connected to one of a pilot supply port and a pilot drain port opened in a valve hole to control a pilot control hydraulic pressure, and a pilot control means for pressing and controlling the pilot spool in a pilot control hydraulic pressure increasing direction Press the pilot spool in the pilot control hydraulic pressure reducing direction. In a pilot-type pressure control valve comprising an ilot reaction force means and two low-pressure chambers respectively formed facing both end faces of the pilot spool, the two low-pressure chambers are formed in a valve body so as to communicate with each other. A communication passage; a buffer orifice provided in the middle of the communication passage; and a first sub-drain passage and a second sub-drain formed in the valve body by communicating each of the low-pressure chambers with the main drain passage. A passage, a first back pressure preventing orifice provided in the middle of the first sub-drain passage, and a second back pressure preventing orifice provided in the middle of the second sub-drain passage. A pressure control valve, comprising: