JP3847553B2 - Flow control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention sends hydraulic oil discharged from a pump to a predetermined hydraulic device such as a power steering device through a throttle passage (metering orifice) and returns excess hydraulic oil to the pump side via a bypass. The present invention relates to a flow control device, and in particular, a path for feeding back the hydraulic pressure of the hydraulic equipment input to the downstream side of the metering orifice to the spool rear chamber side is provided not in the valve housing but in another place. The present invention relates to the flow rate control device.
[0002]
[Prior art]
As shown in FIG. 5, the conventional flow rate control device has a constant flow rate control spool 10 and a spring 80 inside a valve housing 50 provided integrally with a pump housing, and at the opening of the valve housing 50. Has a union 90, and a metering orifice 30 formed of a throttle passage is provided in the union 90. In the above structure, the metering orifice is provided between the downstream side of the metering orifice 30 and the spool rear chamber 70 where the constant flow rate control spring 80 is provided. A union bypass path 60 is provided for feeding back the hydraulic pressure of the hydraulic equipment, which is the hydraulic pressure downstream of 30. Further, in the spool 10 having the above-described configuration, when the working oil pressure of the hydraulic equipment, which is the pressure downstream of the metering orifice 30, rises abnormally, the pressure oil (working oil) that forms this abnormal oil pressure A relief mechanism 110 is provided for releasing the air. Further, a filter 150 for capturing foreign matter generated in the hydraulic system is provided in such a spool 10 and on the spool rear chamber 70 side.
[0003]
[Problems to be solved by the invention]
By the way, as shown in FIG. 5, the union bypass path 60 is provided with a long hole by drilling means or the like, and a ball for closing the opening at the position of the opening to the valve housing 50 body. It is formed by fitting 650 or the like. Therefore, in order to form the union bypass path 60, in addition to the drill hole processing or the like, a work of fitting the ball 650 is required. The work of fitting the ball 650 (insertion work) is complicated because the ball itself needs to be held at an appropriate position, and there is a problem in work efficiency. In order to solve such problems, it is an object of the present invention to provide a flow rate control device having a configuration in which drill hole machining and ball insertion work in a valve housing can be omitted. (Problem).
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the following measures are taken in the present invention. That is, in the invention according to claim 1, the hydraulic oil discharged from the pump is sent to a predetermined hydraulic device through a predetermined throttle passage, and is operated according to a differential pressure across the throttle passage, Accordingly, with respect to the flow rate control device including a spool that operates to recirculate excess hydraulic oil to the pump suction port side, a hollow rod is passed through the spool and the throttle passage in the spool. In addition, a metering orifice is formed between the outer diameter portion of the hollow rod and the throttle passage, and hydraulic oil downstream of the metering orifice A configuration is adopted in which the spool is introduced into one chamber side of the spool via a path in the hollow rod.
[0005]
By adopting such a configuration, in the present invention, a path for feeding back the hydraulic pressure generated on the downstream side of the metering orifice to the rear chamber side of the spool is provided in the hollow portion of the hollow rod. It is no longer necessary to provide the above-mentioned path in a separate valve housing or the like. In other words, the valve housing and the like can be reduced in size, and further, drilling work in the valve housing and clogging work such as ball driving into the drill hole opening are not required. As a result, it is possible to improve the efficiency of the assembly work. In addition, there is no need to worry about leakage of hydraulic oil to the outside, and reliability can be improved.
[0006]
Next, the invention described in claim 2 will be described. The basic point of this is the same as that of the first aspect. That is, according to the present invention, in the flow rate control device according to claim 1, the outer diameter of the hollow rod gradually increases at the one end side of the hollow rod and in the throttle passage. A changing taper portion is provided, whereby a gap area formed between the throttle passage and the outer diameter surface of the taper portion of the hollow rod is gradually changed. By adopting such a configuration, in the present invention, the flow control device can exhibit a drooping function by changing the gap area formed around the outer diameter surface of the tapered portion. . The drooping performance can be changed depending on the taper angle at the tapered portion, and the performance of the flow control device is adjusted to the optimum state for the hydraulic equipment by changing the taper angle. Will be able to.
[0007]
Next, an invention according to claim 3 will be described. The basic point of this is the same as that of the first aspect. That is, in the present invention, in the flow rate control device according to claim 1, a space portion having a circular cross-sectional shape is provided in the spool, and the hollow shape is provided at the hollow rod existing in the space portion. A seat valve having a relative sliding movement in the axial direction on the rod and having a passage in which hydraulic oil flows in the outer peripheral surface portion of the rod with respect to the inner peripheral surface of the spool space portion. And a spring that operates to constantly press the seat valve against a spool end formed on one end of the spool, thereby providing a cone surface of the seat valve and the spool end. In general, the hydraulic fluid does not flow between the valve and the seat valve when the hydraulic oil pressure exceeds a predetermined value. Serial against the spring reaction force of the spring was to adopt a configuration which is adapted to form a relief mechanism so as to move on the said hollow rod in the axial direction.
[0008]
By adopting such a configuration, in the present invention, the relief mechanism can be formed in the hollow rod and the spool in which the hollow rod is installed, and the relief mechanism is provided on the hydraulic equipment side. A path for propagating the operating hydraulic pressure (hydraulic pressure) can be formed with the hollow portion of the hollow rod. Accordingly, there is no need to separately provide the above-mentioned path path in the valve housing or the like, and drill hole processing for forming the path path and plugging work for the drill hole opening are not necessary. As a result, it is possible to improve the efficiency of the assembly work of the entire flow control device.
[0009]
Next, an invention according to claim 4 will be described. This also has the same basic points as those described in claim 1 above. That is, in the present invention, the flow rate control device according to claim 1 is formed of a mesh-like member at one end portion side of the hollow rod and at the end portion existing on the spool end portion side. A configuration in which a filter is provided is adopted. By adopting such a configuration, in the present invention, the filter can be installed in the spool, and the filter can be taken longer overall. That is, according to the present invention, the moving range of the filter can be set large (wide) in the spool rear chamber, and therefore the filter itself can be set large (long). As a result, the screen portion of the filter can be widely used, and the occurrence of a clogging phenomenon in the filter portion can be suppressed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the present embodiment relates to a valve housing 88 formed integrally with the pump housing, and a throttle passage provided in the valve housing 88 and provided in the union 3 described later. The metering orifice 315 formed at 31 has a spool 1 that operates according to the differential pressure across the metering orifice 315, and is provided so as to penetrate the spool 1 and the throttle passage 31. A hollow rod (hollow rod) 5 that is installed to reciprocate linearly in the interior and contributes to the formation of the metering orifice 315 and the relief mechanism, and the opening of the valve housing 88. And a union 3 provided so as to face the spool 1. Than it is.
[0011]
In such a basic configuration, a spool head chamber 61 and an oil introduction chamber 6 are provided on the upstream side of the throttle passage 31 of the union 3 and opposite the head 17 of the spool 1. In addition, the oil introduction chamber 6 is connected to a supply path 66 for introducing discharge oil (operating oil) from the pump. Further, a bypass path 8 connected to a pump suction port (not shown) is provided around the shoulder 171 of the head 17 of the spool 1, and a reservoir (not shown) is provided in the middle of the bypass path 8. The suction passage 4 that leads to (1) is opened. Further, on the downstream side (rear stream side) of the throttle passage 31 of the union 3, a delivery port 39 for sending hydraulic oil to hydraulic equipment such as a power steering device is provided.
[0012]
A spool rear chamber 7 is formed on the rear side opposite to the head 17 of the spool 1, and a spring 71 for applying a spring reaction force to the spool 1 is formed in the spool rear chamber 7. Is provided. In such a configuration, a hollow rod (hollow rod) is provided in the spool 1 and the union 3 so that reciprocal linear movement is possible in the axial direction in the spool 1 and the union 3. ) 5 is provided. A pass path 55 is formed to connect the spool rear chamber 7 and the delivery port 39 with the hollow portion of the hollow rod 5. Accordingly, the oil pressure downstream of the metering orifice 315 formed in the throttle passage 31 is transmitted to the spool rear chamber 7 via the path 55, and the metering is supplied to the spool 1. The differential pressure across the orifice 315 acts. A damping orifice 51 is provided at the end of the hollow rod 5 on the delivery port 39 side. Therefore, the load pressure from the power steering device or the like is transmitted (feedback) to the spool rear chamber 7 via the delivery port 39, the damping orifice 51, and the path 55. Further, a taper portion 52 whose outer diameter surface has a predetermined inclination angle is provided at a position of the hollow rod 5 in the throttle passage 31. The opening area (gap area) of the metering orifice 315 formed by the gap between the outer diameter surface of the taper portion 52 and the throttle passage 31 changes, and the drooping function is exhibited.
[0013]
As shown in FIG. 1, the seat valve 11 having a cone shape and the seat valve 11 are always pressed in a fixed direction around the hollow rod 5 having the above structure and inside the spool 1. A relief mechanism comprising a spring 12 is provided. Specifically, as shown in FIG. 1, a space portion 15 having a circular cross-sectional shape is provided inside the spool 1, and the cone-shaped seat valve 11 and the spring 12 are provided in the space portion 15. is set up. The spool 1 is provided with a passage 18 connected to the bypass passage 8, and the space 15 is connected to the bypass passage 8 through the passage 18.
[0014]
The seat valve 11 having such a configuration as shown in FIG. 1 has an overall cone shape, and is provided with a conical seal surface 111 on one end surface, A spring receiving surface to which a spring reaction force of the spring 12 is input is formed on the other end surface. Due to this spring reaction force, the seal surface 111 is constantly pressed against the spool end 19 provided at the end of the spool 1 on the side of the spool rear chamber 7, thereby ensuring liquid tightness at the seal surface 111. It is like that. Further, as shown in FIG. 1, the seat valve 11 is mounted in the space 15 in the spool 1 so as to be able to slide in the axial direction on the outer peripheral surface of the hollow rod 5. Has been. In addition, as shown in FIG. 2, the seat valve 11 having such a configuration has a cutout shape on the circumference between the inner peripheral surface of the space portion 15 of the spool 1 and the outer peripheral surface portion. A plurality of passages 115 are provided. When the fluid tightness in the seal surface 111 is released, the passage 115 communicates the spool rear chamber 7 side and the bypass passage 8 side.
[0015]
One end face of the hollow rod 5 is located in a space 15 provided inside the spool 1 and opposed to the seat valve 11 with the spring 12 in between. An umbrella-shaped flange 56 that serves as a receiving portion of the spring 12 and whose other surface performs the same sealing function as the sealing surface 111 of the seat valve 11 is provided integrally with the hollow rod 5. Yes. The surface of the umbrella-like flange 56 is normally pressed against the head 17 side of the spool 1 by the spring reaction force of the spring 12 in the same manner as the seat valve 11. The sealing performance is maintained with respect to the spool head chamber 61 formed on the portion 17 side. Further, the outer peripheral surface of the flange 56 is provided with a passage 565 composed of a through passage on the circumference thereof, like the seat valve 11.
[0016]
Further, as shown in FIG. 1, a mesh-like filter 9 is provided at the spool rear chamber 7 side, which is one end side of the hollow rod 5 having such a configuration. The filter 9 is provided in a spool end 19 installed on the spool rear chamber 7 side of the spool 1. Accordingly, a sufficient distance is secured between the position where the main filter 9 is provided and the rear wall 87 of the spool rear chamber 7 provided in the valve housing 88. Can be taken long enough. As a result, the screen area of the filter 9 can be increased.
[0017]
The operation mode of the embodiment having such a configuration will be described with reference to FIGS. First, when the pump starts operating, the pressure oil is discharged and introduced into the oil introduction chamber 6 via the oil supply path 66 of FIG. In such a state, when the temperature of the discharged oil is in a normal temperature state and the fluidity of the discharged oil is high, the flow control device in the present embodiment operates normally and has a predetermined flow control action. To do. That is, the discharged oil discharged from the pump is guided from the oil introduction chamber 6 to the spool head chamber 61 through the first orifice 36 provided in the union 3. From here, it is sent from a delivery port 39 to hydraulic equipment such as a power steering device via a metering orifice 315 provided in the throttle passage 31 of the union 3. When the pump speed increases to some extent and the discharge flow rate exceeds a predetermined value, the spool 1 operates against the spring reaction force of the spring 71 by the action of the differential pressure generated around the metering orifice 315. The shoulder portion 171 of the spool 1 is retracted to bring the spool head chamber 61 and the supply path 66 and the bypass path 8 into communication. As a result, surplus discharged oil is recirculated to the bypass path 8, whereby the flow rate of the pressure oil delivered from the delivery port 39 becomes a constant value. That is, it becomes a constant flow rate state.
[0018]
When the pump rotational speed further increases and the discharge flow rate from the pump increases, the hollow rod 5 moves backward together with the spool 1 toward the spool rear chamber 7 side, and the taper portion 52 of the hollow rod 5 is removed. It is located in the throttle passage 31. That is, the opening area (gap area) of the metering orifice 315 is reduced. As a result, the amount of oil fed from the delivery port 39 to the hydraulic equipment such as the power steering device is reduced, and the drooping function is exhibited.
[0019]
Further, in such a flow rate control state, when the load pressure of the hydraulic equipment is abnormally increased, the load pressure is transferred from the delivery port 39 to the spool rear chamber 7 via the damping orifice 51 and the path path 55. Propagated. As a result, the abnormal load pressure acts on the seal surface 111 of the seat valve 11 located on the spool rear chamber 7 side. In this case, in the present embodiment, the hollow rod 5 has a diameter (opening diameter D) at the opening to the spool rear chamber 7 side of the spool end 19 with which the seal surface 111 is in contact. Further, the seal surface 561 of the umbrella-shaped flange 56 has a larger value than the diameter (opening diameter d) of the opening to the head 17 side of the spool 1. That is, the pressure receiving area of the sealing surface 111 of the seat valve 11 is set to be larger than the pressure receiving area of the sealing surface 561 of the flange 56. Therefore, when a load pressure higher than the set value is applied, the seat valve 11 moves to the right against the spring reaction force of the spring 12 to open the passage 115 provided in the seat valve 11. As a result, the high pressure hydraulic pressure on the spool rear chamber 7 side is released to the bypass passage 8 via the passage 115, the space portion 15 in the spool 1, and the passage 18. As a result, the hydraulic pressure on the spool rear chamber 7 side decreases, the spool 1 itself moves back to the spool rear chamber 7 side against the spring reaction force of the spring 71, and the shoulder portion 171 of the spool 1 is on the bypass path 8 side. Open to. As a result, the high-load pressure oil on the delivery port 39 side is released to the bypass path 8 side via the spool head chamber 61, and the relief function is exhibited.
[0020]
In addition to such a relief action, when the temperature of the hydraulic oil is low, that is, at the time of so-called low temperature starting, etc., the viscosity of the hydraulic oil is generally high. The relief mechanism does not operate smoothly, and as a result, the pump internal pressure may increase abnormally. That is, an abnormal increase in the low temperature surge pressure occurs due to the surging phenomenon at the low temperature start. In contrast, in the present embodiment, the seal surface 561 of the flange 56 provided integrally with the hollow rod 5 is against the spring reaction force of the spring 12 toward the spool rear chamber 7 side. It will be avoided by retreating. That is, when the cold start is started, the pressure in the oil introduction chamber 6 and the spool head chamber 61 is increased by introducing the hydraulic oil from the supply passage 66. This increased pressure (hydraulic pressure) acts on the sealing surface 561 of the flange 56 through a gap formed between the hollow rod 5 and an opening provided in the head portion 17 of the spool 1. To do. As a result, the flange 56 moves backward toward the spool rear chamber 7 against the spring reaction force of the spring 12. As a result, the spool head chamber 61 communicates with the bypass passage 8 via the passage 565 provided in the outer peripheral portion of the flange 56, the space portion 15 formed in the spool 1, and the passage 18 provided in the spool 1. In other words, the hydraulic pressure around the spool head chamber 61 that has become high pressure is released to the bypass path 8 side. Therefore, an increase in the low temperature surge pressure is avoided.
[0021]
Next, a modified example (second embodiment) of the present embodiment will be described with reference to FIGS. The basic point of this is the same as that of the first embodiment. The difference is in terms of the configuration of the drooping generation mechanism. That is, in the present embodiment, the drooping mechanism portion is provided at the sub spool 2 provided so as to face the spool 1 and at the end of the sub spool 2 on the delivery port 39 side. Thus, the metering orifice 29 whose opening area is changed by the operation of the sub spool 2 is formed. Specifically, this drooping mechanism is provided at the oil introduction chamber 6 at one end of the union 3 and facing the head 17 of the spool 1 as shown in FIG. Pressure inlet hole 21, sub-spool 2 provided in the union 3, spring 25 for restricting movement of the sub-spool 2, and metering orifice provided on one end side of the sub-spool 2 29 is formed. The sub spool 2 operates to change the opening area of the metering orifice 29. As shown in FIG. 4, the shape of the opening forming the metering orifice 29 is a deformed compound circle formed by continuously providing small opening holes 292 on both sides of the large opening hole 291. It consists of forms. Then, with respect to the metering orifice 29 having such an opening shape, the hollow rod 5 is always inserted into the large opening hole 291 and the end surface 22 of the sub-spool 2 comes into contact with the opening. The area of the part is reduced. As a result, the amount of hydraulic oil passing through the metering orifice 29 is reduced, and the drooping function is exhibited. In addition, a pressure introduction hole 21 is provided in such a portion of the union 3 facing the oil introduction chamber 6, and one end of the pressure introduction hole 21 opens to the shoulder portion 23 of the sub spool 2. That's what it is like. By adopting such a configuration, when the pump rotation speed increases and the pump discharge flow rate increases, the pressure in the oil introduction chamber 6 increases. As a result, the pressure oil is operated at the shoulder portion 23 of the sub spool 2 through the pressure introducing hole 21 to move the sub spool 2 toward the metering orifice 29 against the spring reaction force of the spring 25. As a result, the end surface 22 of the sub-spool 2 closes the small opening hole 292 that forms the metering orifice 29. That is, the opening area of the metering orifice 29 is reduced. As a result, the amount of hydraulic oil sent from the delivery port 39 to the hydraulic equipment is reduced, and the drooping function is exhibited.
[0022]
The configuration on the spool 1 side in the present embodiment having such a configuration is the same as that in the first embodiment. The hollow rod 5 is inserted (attached) so as to penetrate the spool 1 and the sub spool 2 having such a configuration. As shown in FIG. 3, the hollow rod 5 in the present embodiment has a straight pipe shape on the side engaged with the metering orifice 29, as in the first embodiment. The taper part is not provided. However, the rest is the same as that of the first embodiment shown in FIG. 1, and a damping orifice 51 is provided at the end located on the delivery port 39 side, and the spool rear portion A filter 9 is mounted at the end located on the chamber 7 side.
[0023]
【The invention's effect】
According to the present invention, the hydraulic oil discharged from the pump is sent to a predetermined hydraulic device through a predetermined throttle passage, and is operated in accordance with the differential pressure across the throttle passage, thereby operating excessively. Relating to a flow rate control device having a spool that operates to recirculate oil to a pump suction port side, a hollow rod passes through the spool and the throttle passage, and reciprocates linearly. The metering orifice is formed between the outer diameter portion of the hollow rod and the throttle passage, and the hydraulic oil downstream of the metering orifice is placed in the hollow rod. Since the configuration is such that the spool is introduced to one chamber side of the spool via the path, the hydraulic pressure generated on the downstream side of the metering orifice is increased. Path path for feeding back to the rear chamber side of the spool, can now be formed in a hollow portion of the hollow rod, no longer needs to be provided in the path path separately valve housing or the like. As a result, drilling in the valve housing, etc., and clogging work such as ball driving into the drill hole opening are not required, and the assembly work of the entire flow control device can be improved. .
[0024]
Further, a tapered portion in which the outer diameter of the hollow rod gradually changes is provided on one end side of the hollow rod and in the throttle passage. In the structure in which the gap area formed between the taper portion and the outer diameter surface of the hollow rod gradually changes, the gap formed around the outer diameter surface of the taper portion. Due to the change in area, this flow control device can be made to exhibit a drooping function. Further, by appropriately selecting the taper angle at the taper portion, it becomes possible to change the drooping performance, so that the performance of the flow control device can be adjusted to the optimum state for the hydraulic equipment. Became.
[0025]
Further, in the present invention, a space portion having a circular cross-sectional shape is provided in the spool, and the hollow rod existing in the space portion is relatively slid in the axial direction on the hollow rod. A seat valve having a cone shape and having a passage through which hydraulic oil flows to the inner peripheral surface of the spool space portion is provided on the outer peripheral surface portion of the cone valve. A spring that is always pressed against the spool end portion formed on one end side of the spool is provided, so that hydraulic oil is normally not allowed between the cone surface of the seat valve and the spool end portion. When the hydraulic oil pressure exceeds a predetermined value, the seat valve is moved against the spring reaction force of the spring. Since the relief mechanism that moves the rod in the axial direction is provided, the relief mechanism is formed in the hollow rod and the spool on which the hollow rod is installed. As a result, a path for transmitting the hydraulic pressure (hydraulic pressure) on the hydraulic device side to the relief mechanism can be formed with the hollow portion of the hollow rod. Accordingly, it is not necessary to separately provide the above-mentioned path path in the valve housing or the like, and drilling for forming the path path and plugging work for the drill hole opening are not necessary. As a result, it is possible to improve the efficiency of the assembly work of the entire flow control device.
[0026]
Further, in the present invention, a configuration is adopted in which a filter made of a mesh-like member is provided at one end of the hollow rod and at the end existing on the spool end side. As a result, the filter can be installed in the spool, and the filter can be taken longer overall. That is, in the present invention, the moving range of the filter can be set large (wide) in the rear chamber of the spool, and therefore the filter itself can be set large (long). As a result, the screen portion of the filter can be widely used, and the occurrence of clogging in the filter portion can be suppressed.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing the overall configuration of the present invention and a first embodiment.
2 is a cross-sectional view taken along the line AA in FIG. 1, showing the overall configuration around the seat valve that forms the main part of the present invention.
FIG. 3 is a longitudinal sectional view showing an overall configuration of a second embodiment according to the present invention.
4 is a cross-sectional view taken along the line BB in FIG. 3 showing a configuration around a metering orifice in the second embodiment.
FIG. 5 is a longitudinal sectional view showing an overall configuration of a conventional example.
[Explanation of symbols]
1 spool
11 Seat valve
111 Seal surface
115 passage
12 Spring
17 head
171 shoulder
15 Space
18 passage
19 Spool end
2 Sub spool
21 Pressure introduction hole
22 End face
23 shoulder
25 Spring
29 Metering orifice
291 large opening hole
292 Small opening hole
3 Union
31 Restricted passage
315 Metering orifice
36 First orifice
39 Outlet
4 suction paths
5 Hollow rod
51 Damping orifice
52 Taper
55 path
56 Flange
561 Seal surface
565 passage
6 Oil introduction chamber
61 Spool head chamber
66 Supply path
7 Spool rear chamber
71 Spring
8 Bypass
87 Rear wall
88 Valve housing
9 Filter

Claims (4)

The hydraulic oil discharged from the pump is sent to a predetermined hydraulic device through a predetermined throttle passage, and is operated according to the differential pressure across the throttle passage, thereby removing excess hydraulic oil on the pump suction port side. In the flow control device having a spool that is operated so as to recirculate to the inside of the spool, a hollow rod is inserted into the spool so as to pass through the spool and the throttle passage, and reciprocating linear motion is possible. The metering orifice is formed between the outer diameter portion of the hollow rod and the throttle passage, and the working oil downstream of the metering orifice is passed through the path in the hollow rod. A flow rate control device, wherein the flow rate control device is introduced into one chamber side of the spool. The flow rate control device according to claim 1, wherein a tapered portion where the outer diameter of the hollow rod gradually changes is provided at one end portion side of the hollow rod and present in the throttle passage. Accordingly, the flow rate control device is characterized in that the gap area formed between the throttle passage and the outer diameter surface of the tapered portion of the hollow rod gradually changes. 2. The flow rate control device according to claim 1, wherein a space portion having a circular cross-sectional shape is provided in the spool, and the hollow rod on the hollow rod existing in the space portion is arranged in the axial direction thereof. A seat valve having a cone-like shape and having a passage through which hydraulic oil flows to the inner peripheral surface of the spool space portion is provided on the outer peripheral surface portion of the seat valve. A spring that operates to constantly press the valve against the spool end portion formed on one end side of the spool is provided, so that normally, between the cone surface of the seat valve and the spool end portion is provided. The hydraulic oil is prevented from flowing, and when the hydraulic oil pressure exceeds a predetermined value, the seat valve is resisted against the spring reaction force of the spring. Flow control device characterized by comprising a structure which is adapted to form a relief mechanism so as to move on the said hollow rod in the axial direction of Te. 2. The flow rate control device according to claim 1, wherein a filter made of a mesh-like member is provided on one end side of the hollow rod and on an end portion existing on the spool end side. A flow control device.

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