JP2002323168A - Bleeder structure in valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve responsiveness of a valve by surely deaerating in pilot pressure oil in the pilot operation type valve, operated by the pilot pressure to be introduced in a pilot chamber. SOLUTION: A bleeder throttle passage 19, which is to be connected to a tank return oil passage 16, is formed in the upper part of an upper side pilot chamber 8A for introducing the pilot pressure oil and a thermal expansion member 18 or enlarging the area of the opening of the throttle passage, according to the temperature of the pilot pressure oil, is disposed in the throttle passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an air vent structure for a pilot-operated valve operated by pilot pressure.

[0002]

2. Description of the Related Art In general, a hydraulic construction machine such as a hydraulic shovel is configured to operate various actuators such as a traveling motor, a swing motor, a boom cylinder, and a bucket cylinder with hydraulic pressure. In some cases, a pilot-operated valve that operates with a pilot pressure output from a pilot valve based on operation of an operating tool is used as a valve for controlling the supply and discharge of pressure oil to these actuators. By the way, in such a pilot-operated valve, if air is mixed in the pilot pressure oil, there is a concern that the response of the valve may be delayed or the response accuracy may be reduced. Therefore, conventionally, as shown in FIG. 5, a notch (notch) is provided at the end of the spool 6 constituting the valve to allow the pilot chamber 8A and the drain passage 13 to communicate with each other when the spool 6 moves to a full stroke. 6a, the pilot pressure oil and the air contained in the pilot pressure oil are discharged through the notch 6a.

[0003]

By the way, since the notch 6a communicates with the drain passage 13 when the spool 6 moves to the full stroke, the conventional one has a structure in which the moving stroke of the spool 6 is small. That is, there is a problem that the air is not bleed out in a state where the actuator is finely operated to operate the actuator slowly. In this case, since the air has a low specific gravity, it tends to accumulate in the upper portion of the pilot chamber 8A. However, as shown in FIG. There are problems,
These have problems to be solved by the present invention. Further, when the oil temperature of the pilot pressure oil is low at the time of cold or start-up, the viscosity increases, but the pilot pressure oil having such a high viscosity is supplied to the drain passage 13 through the notch 6a.
In order to flow the air, the air cannot be removed unless the flow is generated by increasing the notch area of the notch 6a.
On the other hand, when the notch area of the notch 6a is increased, when the oil temperature of the pilot pressure oil increases and the viscosity decreases, the amount of oil flowing from the pilot chamber 8A to the drain passage 13 increases, and the response accuracy of the valve increases. There was also a problem that had to be solved.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has been made to solve these problems, and has been made in order to solve the above problems. In the operation type valve, a throttle passage for air release connected to the tank return oil passage is formed above the pilot chamber.
By doing so, when air enters the pilot pressure oil, the air can be efficiently guided to the throttle passage and discharged to the tank return oil passage, and the air can be discharged regardless of the valve operation amount. It will be possible to pull out,
This can contribute to improving the response of the valve. According to the present invention, in a pilot-operated valve operated by a pilot pressure introduced into a pilot chamber, a throttle passage for bleeding air connected to a tank return oil passage is formed in the pilot chamber, and the throttle passage is formed. In addition, a thermal expansion member for increasing or decreasing the opening area of the throttle passage in accordance with the oil temperature of the pilot pressure oil is provided. In this manner, when the oil temperature of the pilot pressure oil is low, the opening area of the throttle passage is widened, so that even high-viscosity oil can flow through the throttle passage without interruption, while the oil temperature is high. In this case, the opening area of the throttle passage is reduced, and it is possible to avoid an increase in the amount of oil discharged from the throttle passage. Therefore, it is possible to reliably release air without being affected by the oil temperature and to have excellent responsiveness. Can be provided. Further, in the present invention, in a pilot-operated valve operated by pilot pressure introduced into a pilot chamber, a throttle passage for air release connected to a tank return oil passage is formed above the pilot chamber, In the throttle passage, a thermal expansion member for increasing or decreasing the opening area of the throttle passage in accordance with the oil temperature of the pilot pressure oil is provided. By doing so, when air enters the pilot pressure oil, the air can be efficiently guided to the throttle passage and discharged to the tank return oil passage, and the air can be discharged regardless of the valve operation amount. In addition, when the oil temperature of the pilot pressure oil is low, the opening area of the throttle passage is widened, so that even high-viscosity oil can flow through the throttle passage without interruption, while the oil temperature is high. In this case, the opening area of the throttle passage is reduced, and it is possible to avoid an increase in the amount of oil discharged from the throttle passage. Therefore, it is possible to reliably release air without being affected by the oil temperature and to have excellent responsiveness. Can be provided. In these components, the thermal expansion member is provided in a plug for closing an opening formed in the valve body, so that the thermal expansion member can be provided using the plug. In addition, by connecting the throttle passage to a drain passage formed in the valve body and connecting the drain passage to the tank return oil passage, a separate pipe from the throttle passage to the tank return oil passage is separately provided. Without using the drain passage, the air can be discharged.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to FIGS. In these drawings, reference numeral 1 denotes a control valve unit provided in a hydraulic shovel, and a valve body 2 of the control valve unit 1.
Is formed by integrally assembling a plurality of covers 4 with a body main body 3. The valve body 2 includes a traveling motor, a swing motor, a boom cylinder,
A plurality of control valves 5 for controlling supply and discharge of hydraulic oil to various hydraulic actuators (not shown) such as an arm cylinder are incorporated.

That is, taking an example of an arbitrary control valve 5A among the plurality of control valves 5, a spool 6 constituting the control valve 5A is inserted into the body 3 so as to be movable up and down. Upper and lower covers 4A and 4B disposed above and below the spool 6 are formed with upper and lower pilot chambers 8A and 8B, respectively.
Alternatively, it is configured to move up and down with a movement stroke corresponding to the pilot pressure introduced into the lower pilot chamber 8B, and to control the supply and discharge of the hydraulic oil to the hydraulic actuator.

Reference numeral 9 denotes a pilot valve. When the operator operates the operating tool 10, the pilot valve 9 supplies pilot pressure oil having a pressure corresponding to the operation amount to the upper pilot chamber 8A or the lower pilot chamber 8A. Output to the side pilot room 8B.

On the other hand, the upper cover 4A is provided with a throttle passage 11 extending upward from the upper end of the upper pilot chamber 8A.
Are drilled. The throttle passage 11 communicates with a drain passage 13 formed in the body 3 through a communication passage 12 formed in the upper cover 4A and the body 3. Through a drain port 14 provided in the body 3, it is connected to a tank return oil passage 16 serving as an oil passage returning to the oil tank 15. In the figure, reference numeral 7 denotes a plug for closing an opening formed in the upper cover 4A to form the throttle passage 11.

In the configuration described above, when air is mixed in the pilot pressure oil, the air is carried to the upper pilot chamber 8A together with the pilot pressure oil output from the pilot valve 9 to the upper pilot chamber 8A. The oil is discharged from the upper pilot chamber 8A to the oil tank 15 through the throttle passage 11, further through the communication passage 12, the drain passage 13, and the tank return oil passage 16.

As described above, in the present embodiment, the air mixed in the pilot pressure oil is discharged to the oil tank 15 through the throttle passage 11. In this case, Since the throttle passage 11 is formed at the upper end of the upper pilot chamber 8A, air having a low specific gravity can be efficiently guided to the throttle passage 11, and air can be removed regardless of the movement stroke of the spool 6. it can. Further, even if air remains in the upper pilot chamber 8A after the operation of the operation tool 10 is stopped, the air moves to the upper part of the upper pilot chamber 8A and is discharged to the throttle passage 11 because of its low specific gravity. Therefore, air can be reliably removed from the pilot pressure oil, which can contribute to the improvement of the responsiveness of the control valve 5A. Also, while the operating tool 10 is operated, a part of the pilot pressure oil output from the pilot valve 9 is supplied to the oil tank 15 through the throttle passage 11.
As a result, the pilot oil is circulated and the pilot system has a heat-up function. In addition, this is a simple structure in which a throttle passage 11 is formed at the upper end of the upper pilot chamber 8A and the throttle passage 11 is connected to a drain passage 13 formed in the body 3 of the conventional art. There is an advantage that the present invention can be implemented without significantly changing the control valve unit.

Next, a second embodiment of the present invention will be described with reference to FIG.
It will be described based on. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Now, in the second embodiment, the spool 6 is moved up and down by the pilot pressure input to the upper pilot chamber 8A or the lower pilot chamber (not shown) as in the first embodiment. In this case, the hydraulic oil supply / discharge control for the hydraulic actuator is performed. In this case, a through hole 4a is formed in the upper cover 4A so as to penetrate the upper pilot chamber 8A from the upper end to the outside. And the through hole 4
The external opening a is closed by a plug 17 that is screwed in from the outside, and a thermal expansion member 18 having a high thermal expansion coefficient is attached to the lower end of the plug 17.

The throttle passage 19 of the present invention is formed by the clearance between the inner peripheral surface of the through hole 4a and the outer peripheral surface of the thermal expansion material 18.
A portion above the throttle passage 19 is connected to a drain passage 13 formed in the body 3 through a communication passage 12 communicating with the through hole 4a. Thus, the air in the pilot pressure oil flows from the upper pilot chamber 8A to the throttle passage 1.
9 through a communication passage 12, a drain passage 13, and a tank return oil passage 16 to an oil tank 15.

Here, the opening area of the throttle passage 19 (the clearance between the inner peripheral surface of the through hole 4a and the outer peripheral surface of the thermal expansion material 18) changes widely and narrowly in accordance with the oil temperature change of the pilot pressure oil. I do. That is, when the oil temperature is low, the opening area of the throttle passage 19 is large because the thermal expansion material 18 is contracted, so that even low-temperature, high-viscosity oil can flow without stagnation. I have. On the other hand, as the oil temperature increases, the oil flow becomes smoother, but in this case, the thermal expansion material 18 expands to reduce the opening area of the throttle passage 19, thereby reducing the amount of oil discharged from the throttle passage 19. It is possible to avoid such a problem that the response is impaired due to too much.

In the second embodiment, the same operation and effect as those of the first embodiment can be obtained. However, the second embodiment has a throttle which serves as an air discharge passage. In the passage 19, a thermal expansion material 18 for increasing and decreasing the opening area of the throttle passage 19 in accordance with a change in the oil temperature of the pilot pressure oil is arranged. As a result, when the oil temperature of the pilot pressure oil is low, the opening area of the throttle passage 19 becomes large, and even if the oil has a high viscosity, the air can flow through the throttle passage 19 without stagnation and the air can be reliably removed. As the oil temperature increases, the opening area of the throttle passage 19 decreases, and it is possible to avoid a problem that the amount of oil discharged from the throttle passage 19 is too large and the response is impaired. It is possible to provide a control valve that can reliably release air without being affected by the influence and has excellent responsiveness.

Further, the present invention is not limited to the above first and second embodiments. For example, FIG.
As in the third embodiment shown in FIG. 1, the present invention can also be implemented in a configuration in which the spool 6 moves in the left-right direction. In this case, the pilot chambers are formed on the left and right sides of the spool 6 (the right pilot chamber is omitted in FIG. 4), but by providing the throttle passages 19 above the left and right pilot chambers, both pilot chambers are formed. Air can be removed from the chamber. In FIG. 4, reference numeral 4C denotes a left cover assembled to the left side of the body 3, and 8C denotes a left pilot chamber formed on the left cover 4C. In FIG. 4, the body 3, the pilot valve 9, the operating tool 10, the communication passage 12, and the drain passage 1 are shown.
3. The plug 17, the thermal expansion member 18 are the same as those of the first and second embodiments.

[Brief description of the drawings]

FIG. 1 is a sectional view of a control valve unit according to a first embodiment.

FIG. 2 is a partially enlarged view of a section taken along line XX of FIG.

FIG. 3 is a sectional view of a main part of a control valve unit according to a second embodiment.

FIG. 4 is a sectional view of a main part of a control valve unit according to a third embodiment.

FIG. 5 is a sectional view of a main part of a control valve unit showing a conventional example.

[Explanation of symbols]

 2 Valve body 3 Body main body 4A Upper cover 4C Left cover 5A Control valve 8A Upper pilot chamber 8C Left pilot chamber 11 Throttle passage 13 Drain passage 16 Tank return oil passage 17 Plug 18 Thermal expansion member 19 Throttle passage

Claims (5)

[Claims] 1. A pilot-operated valve operated by a pilot pressure introduced into a pilot chamber, wherein a throttle passage for air release connected to a tank return oil passage is formed above the pilot chamber. Air bleeding structure in the valve. 2. A pilot-operated valve operated by a pilot pressure introduced into a pilot chamber, wherein a throttle passage for air release connected to a tank return oil passage is formed in said pilot chamber, and said throttle passage is formed. And a thermal expansion member for increasing or decreasing the opening area of the throttle passage according to the oil temperature of the pilot pressure oil. 3. A pilot-operated valve operated by a pilot pressure introduced into a pilot chamber, wherein a throttle passage for air release connected to a tank return oil passage is formed above the pilot chamber. An air vent structure in a valve, wherein a thermal expansion member for increasing or decreasing the opening area of the throttle passage in accordance with the oil temperature of the pilot pressure oil is provided in the throttle passage. 4. The air vent structure in a valve according to claim 2, wherein the thermal expansion member is provided on a plug for closing an opening formed in the valve body. 5. The throttle passage according to claim 1, wherein the throttle passage is connected to a drain passage formed in the valve body, and is connected to the tank return oil passage from the drain passage. Air bleeding structure in a valve.