Valves, hydraulic systems, construction machinery, and mobile valve cores

Abstract

The present invention provides a valve, a hydraulic system, a construction machine, and a movable valve core. The valve of the present invention comprises: a housing having a housing for storing a working fluid; and a movable valve core housed in the housing space. When a predetermined pressure is applied and the working fluid stagnates, the movable valve core moves within the housing space to discharge the working fluid accumulated in the housing space to the outside of the housing space.

Description

Technical Field

[0001] The present invention relates to an automated valve, a hydraulic system, a construction machine and a movable valve core suitable for hydraulic control. Background Art

[0002] As a hydraulic circuit for construction machinery, hydraulic circuits having a proportional solenoid valve in the control valve are increasing. The proportional solenoid valve is composed of precision components such as the following, which work by using the small thrust generated by the solenoid and the pressure of the small-diameter valve column. Therefore, a filter is provided on the upstream side of the proportional solenoid valve. The filter captures foreign matter on the upstream side of the proportional solenoid valve to prevent foreign matter (contamination) from entering the proportional solenoid valve. For example, according to the technology described in the referenced ground of Patent Document 1, the mesh size of the filter is reduced, the solenoid valve is protected, and clogging of the filter is suppressed.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 6-81815 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] However, if the filter mesh is made finer to prevent foreign matter from entering the proportional solenoid valve, the working fluid's viscosity increases at low temperatures, increasing the pressure loss of the working fluid as it passes through the filter. Therefore, in proportional solenoid valves, when the working fluid's viscosity is high at low temperatures or when the proportional solenoid valve is abruptly actuated, the working fluid is likely to remain in the filter during the on / off switching of the solenoid valve. This results in a potential response delay in conventional proportional solenoid valves.

[0008] An object of the present invention is to provide a valve, a hydraulic system, a construction machine, and a movable valve core capable of reducing a response delay of a proportional solenoid valve.

[0009] Solutions for solving problems

[0010] A valve in one form of the present invention comprises: a housing having a receiving space for accommodating a working fluid flowing from an upstream side to a downstream side; and a movable valve core, which is accommodated in the receiving space and has a pressure-receiving portion, which bears the pressure of the working fluid stagnant on the upstream side in the receiving space. The movable valve core moves from the upstream side to the downstream side in the receiving space due to the pressure applied to the pressure-receiving portion, and discharges the working fluid on the downstream side in the receiving space to the outside of the receiving space.

[0011] With this configuration, even if the working fluid stagnates midway through the flow path, the working fluid accumulated on the upstream side of the containment space will still move the movable valve core due to the pressure of the working fluid. This allows the working fluid, which has accumulated on the downstream side of the containment space (the oil reservoir), to be supplied to the exterior of the containment space. This reduces delays in the proportional solenoid valve's response, for example, when the proportional solenoid valve is located downstream of the valve.

[0012] In the above configuration, the movable valve element may include a discharge port for discharging the working fluid.

[0013] With this configuration, the working fluid can be discharged from the discharge port as the movable valve element moves.

[0014] In the above configuration, the movable valve element may include: a flow path provided in the pressure receiving portion and through which the working fluid flows from the upstream side to the downstream side; and a filter provided in the flow path.

[0015] With this configuration, the mesh size of the filter can be made finer to improve the foreign matter capture performance, and the response delay of the proportional solenoid valve can be reduced.

[0016] In the above structure, the valve may also include: a bypass flow path, which is different from the housing space, and the bypass flow path is connected to the upstream side relative to the pressure-bearing part in the housing space when the movable valve core moves, so that the working fluid flows around the downstream side relative to the pressure-bearing part in the housing space; and other filters, which are arranged in the bypass flow path.

[0017] With this configuration, in addition to supplying the working fluid from the oil storage space to the downstream side, the working fluid having passed through another filter is also supplied from the bypass flow path to the downstream side. This further reduces the response delay of the proportional solenoid valve.

[0018] In the above configuration, the valve may include a plug that is fitted into the housing space and limits a range of movement of the movable valve element within the housing space.

[0019] With this configuration, a valve having a slidable movable valve element can be realized with a small number of parts.

[0020] The valve of one form of the present invention comprises: a housing, which has a receiving space for accommodating a working fluid flowing from an upstream side to a downstream side; a movable valve core, which comprises: a pressure-receiving portion, which bears the pressure of the working fluid stagnant on the upstream side in the receiving space; a discharge port, which discharges the working fluid on the downstream side of the receiving space to the outside of the receiving space; a flow path, which is arranged in the pressure-receiving portion, for the working fluid to flow from the upstream side to the downstream side; and a filter, which is arranged in the flow path, the movable valve core moves from the upstream side to the downstream side in the receiving space due to the pressure applied to the pressure-receiving portion, and discharges the working fluid to the outside of the receiving space through the discharge port; and a plug, which is embedded in the receiving space to limit the range of movement of the movable valve core in the receiving space.

[0021] With this configuration, even if the working fluid is stagnant midway through the flow path, the working fluid pressure from the working fluid stagnating in the upstream side of the containment space will cause the moving valve core to move. This allows the working fluid, which has accumulated downstream (the oil reservoir) of the containment space, to be supplied to the exterior of the containment space. This reduces delays in the proportional solenoid valve's response, for example, when the proportional solenoid valve is located downstream of the valve.

[0022] The hydraulic system of one form of the present invention comprises: an engine as a driving source; a hydraulic pump, which is driven by the engine to circulate a working fluid; a plurality of actuators, which use the pressure of the working fluid to drive an action object; a proportional solenoid valve, which switches the action of the plurality of actuators; a valve, which is installed on the upstream side of the proportional solenoid valve and comprises: a housing; a receiving space for accommodating the working fluid flowing from the upstream side to the downstream side; and a movable valve core, which has a pressure-receiving portion, which receives the pressure of the working fluid stagnant on the upstream side in the receiving space, and the movable valve core moves from the upstream side to the downstream side in the receiving space due to the pressure applied to the pressure-receiving portion, and discharges the working fluid on the downstream side in the receiving space to the outside of the receiving space; a tank, which stores the working fluid; and a relief valve for adjusting the pressure of the working fluid.

[0023] With this configuration, in a hydraulic system, when a pressure exceeding a predetermined value is applied to the movable valve element and the working fluid stagnates, such as when the viscosity of the working fluid is high at low temperatures, the movable valve element moves. This allows the working fluid accumulated downstream of the accommodation space (the oil reservoir) to be supplied to the outside of the accommodation space, thereby reducing response delays in the proportional solenoid valve.

[0024] A construction machine according to one embodiment of the present invention comprises: a hydraulic system comprising: an engine as a driving source; a hydraulic pump driven by the engine to circulate a working fluid; a plurality of actuators that utilize the pressure of the working fluid to drive an action object; a proportional solenoid valve that switches the action of the plurality of actuators; a valve installed on the upstream side of the proportional solenoid valve and comprising: a housing having a receiving space for accommodating the working fluid flowing from the upstream side to the downstream side; and a movable valve core having a pressure-receiving portion that receives the pressure of the working fluid stagnant on the upstream side in the receiving space, the movable valve core moving from the upstream side to the downstream side in the receiving space due to the pressure applied to the pressure-receiving portion and discharging the working fluid on the downstream side in the receiving space to the outside of the receiving space; a tank that stores the working fluid; and a relief valve for adjusting the pressure of the working fluid; a rotating body that is actuated by the hydraulic system; and a traveling body that supports the rotating body so as to rotate freely, the traveling body being driven by the hydraulic system to travel.

[0025] With this structure, even if the working fluid stagnates midway through the flow path, the working fluid retained on the upstream side of the containment space will still move due to the pressure of the working fluid. This allows the working fluid, which has accumulated on the downstream side of the containment space (the oil storage space), to be supplied to the outside of the containment space. Therefore, in cases where the proportional solenoid valve is located downstream of the valve, for example, it is possible to achieve a construction machine with reduced response delay and faster response to operations, while also reducing the chance of delay.

[0026] A movable valve core in one form of the present invention is accommodated in a receiving space, which is arranged in a shell and accommodates a working fluid flowing from the upstream side to the downstream side. The movable valve core has a pressure-receiving portion, which bears the pressure of the working fluid stagnant on the upstream side in the receiving space. The movable valve core moves from the upstream side to the downstream side in the receiving space due to the pressure applied to the pressure-receiving portion, and discharges the working fluid on the downstream side in the receiving space to the outside of the receiving space.

[0027] With this configuration, a slidable movable valve element can be realized with a small number of parts.

[0028] Effects of the Invention

[0029] According to the present invention, it is possible to reduce a response delay of a proportional solenoid valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the construction machine according to the embodiment of the present invention.

[0031] Figure 2 It is a structural diagram of a hydraulic system in an embodiment of the present invention.

[0032] Figure 3 It is a structural diagram of the valve element in the embodiment of the present invention.

[0033] Figure 4 This is a diagram showing a state where a working fluid flows into a valve element in an embodiment of the present invention.

[0034] Figure 5 It is a diagram showing a state in which a piston of a valve body moves in an embodiment of the present invention.

[0035] Figure 6 It is a diagram showing a modified example of the valve body in the embodiment of the present invention.

[0036] Figure 7 It is a diagram showing another modified example of the valve body in the embodiment of the present invention.

[0037] Description of Reference Numerals

[0038] 1. Hydraulic system; 100. Construction machinery; 101. Rotating unit; 102. Traveling unit; 103. Cab; 104. Boom; 105. Arm; 106. Bucket; 120. Engine; 121. Output shaft; 130. Hydraulic pump; 140. Actuator; 150. Hydraulic control valve; 160. Tank; 170. Proportional solenoid valve; 200. Valve; 201. Piston (moving valve core); 201S. Cavity; 202. Main body; 203. Top surface; 204. Flow path; 205. Step; 206, discharge port; 220, housing; 221, accommodating space; 221A, opening; 221B, thread; 222, step; 223, oil storage space; 224, flow path; 230, supply plug; 231, thread; 232, step; 233, flow path; 234, inlet; 235, outlet; 236, intermediate portion; 250, bypass flow path; 300, relief valve; F, filter; F1, filter; L, axis; P, pilot pump; Q, piping; S, return spring. DETAILED DESCRIPTION

[0039] Next, embodiments of the present invention will be described with reference to the drawings.

[0040] (Construction Machinery)

[0041] like Figure 1 As shown, the construction machine 100 is, for example, a hydraulic excavator. The construction machine 100 includes a revolving body 101 and a traveling body 102. The revolving body 101 is rotatably mounted on the traveling body 102. The revolving body 101 is provided with a hydraulic system 1.

[0042] The revolving structure 101 includes a driver's seat 103 for an operator to sit in; a boom 104 having one end swingably connected to the revolving structure 101 near the driver's seat 103; an arm 105 having one end swingably connected to the other end of the boom 104 (the end (top end) on the side opposite to the operator's cab 103); and a bucket 106 swingably connected to the other end of the arm 105 (the end (top end) on the side opposite to the boom 104). A hydraulic system 1 is provided within the operator's cab 103. The operator's cab 103, boom 104, arm 105, and bucket 106 are driven by working fluid supplied from the hydraulic system 1. The operator's cab 103, boom 104, arm 105, and bucket 106 are examples of objects of motion.

[0043] (Hydraulic System)

[0044] like Figure 2 As shown, the hydraulic system 1 includes: an engine 120 as a driving source; a hydraulic pump 130, which is driven by the engine 120; a plurality of actuators 140, which actuate various parts of the construction machine 100; a hydraulic control valve 150, which switches the actions of the plurality of actuators 140; a tank 160, which stores working fluid; and a relief valve 300 for pressure adjustment.

[0045] The engine 120 is an internal combustion engine that uses gasoline or diesel fuel. The engine 120 includes an output shaft 121. The output shaft 121 is connected to a hydraulic pump 130. A pipe Q is connected to the hydraulic pump 130. The hydraulic pump 130 is driven by the rotation of the output shaft 121. The hydraulic pump 130 flows a working fluid through the pipe Q. A hydraulic control valve 150 is connected to the pipe Q.

[0046] Multiple actuators 140 are connected to the hydraulic control valve 150 via branched piping Q. Multiple hydraulic control valves 150 are provided. The hydraulic control valve 150 switches the hydraulic pressure of the working fluid flowing through the piping Q using multiple valves to supply working fluid to the multiple actuators 140. The multiple actuators 140 drive the cab 103, boom 104, arm 105, bucket 106, and other components. When the pressure in the flow path of the hydraulic circuit of the hydraulic system 1 exceeds a predetermined value, the relief valve 300 releases the pressure.

[0047] The working fluid delivered by the pilot pump P is supplied to the hydraulic control valve 150 via the proportional solenoid valve 170. The pilot pump P is driven by an operator. A valve 200 is provided upstream of the proportional solenoid valve 170. As shown in the figure, the hydraulic system 1 includes the same number of pilot pumps P as the number of proportional solenoid valves 170 (two). However, the hydraulic system 1 may also have a configuration in which a single pilot pump P is shared by multiple proportional solenoid valves 170.

[0048] Next, the valve 200 provided on the upstream side of the proportional solenoid valve 170 will be described.

[0049] like Figure 3 As shown, valve 200 includes a filter F that captures foreign matter. Valve 200 prevents foreign matter from entering proportional solenoid valve 170. Valve 200 includes a piston 201 (moving valve element) that moves according to the pressure of the working fluid, and a housing 220 that houses piston 201. Housing 220, serving as the housing of hydraulic system 1, can be integrally formed or separately formed.

[0050] The piston 201 is formed into a cylindrical shape with a top. The piston 201 has a cylindrical main body 202. The piston 201 has a top surface 203 (pressure-receiving portion) that blocks one end of the main body 202. The main body 202 and the top surface 203 form a cavity 201S inside the piston 201. A discharge port 206 is formed in the main body 202 of the piston 201. The discharge port 206 extends in a direction perpendicular to the axis L of the piston 201. The discharge port 206 connects the cavity 201S and the flow path 224 on the downstream side of the piston 201.

[0051] Top surface 203 is formed into a cylindrical shape with a predetermined width extending from one end of main body 202 toward the other end. A flow path 204 is formed on top surface 203. Flow path 204 extends through top surface 203 along axis L of piston 201. Working fluid flows through flow path 204 along axis L of piston 201. A step 205 is formed on one end of flow path 204, with a diameter larger than that of the other end. A filter F is provided on step 205 to capture foreign matter in the working fluid.

[0052] Filter F captures foreign matter mixed in the working fluid as it flows from flow path 233 upstream of piston 201 into cavity 201S, filtering the working fluid.

[0053] The piston 201 is inserted into a housing 221 formed in the housing 220 via a return spring S. The housing 220 accommodates the piston 201, which is biased by the return spring S, so that it can move freely. The return spring S biases the piston 201 toward the opening of the housing 221. The return spring S is inserted into a cavity 201S of the piston 201.

[0054] Receiving space 221 is formed as a circular cavity that accommodates piston 201. The diameter (inner diameter) of receiving space 221 is slightly larger than the outer diameter of piston 201. Working fluid can enter receiving space 221 through the gap between receiving space 221 and piston 201. However, this gap is very small. Therefore, foreign matter that enters receiving space 221 through the gap is smaller than foreign matter captured by filter F. Therefore, even if such foreign matter enters proportional solenoid valve 170, there will be no problem.

[0055] In addition to the space for accommodating piston 201, housing space 221 also includes an oil storage space 223 for accumulating working fluid, along the axis L. A step 222 is formed in housing space 221 at a position corresponding to discharge port 206 of piston 201, extending in diameter (inner diameter). Step 222 is formed with a width along the axis L such that it remains in constant communication with discharge port 206, even if piston 201 slides in the axis L direction.

[0056] A flow path 224 (outside the housing 221) is connected to the housing 220 so as to communicate with the step 222. The flow path 224 communicates with the proportional solenoid valve 170. An opening 221A is formed at one end of the housing 221. A closed oil reservoir 223 is formed at the other end of the housing 221. Threads 221B are formed on the inner circumference of the opening 221A. The supply plug 230 is inserted into the opening 221A (housing 221) so as to cover the opening 221A.

[0057] The supply plug 230 is cylindrical. One end of the supply plug 230 is formed with a thread 231 that engages with (threads meshing with) the thread 221B. The supply plug 230 is formed with a step 232 that abuts against the housing 220 when screwed into the opening 221A (when tightened). The supply plug 230 is tightened to the opening 221A with the piston 201 pressed in by the return spring S. When the step 232 abuts against the housing 220, the piston 201 is sealed within the housing 221 of the housing 220.

[0058] As a result, piston 201 is biased by return spring S so that top surface 203 abuts supply plunger 230 within containment space 221. Specifically, top surface 203 divides containment space 221 into an upstream side (plunger 230 side) and a downstream side (oil reservoir 223 side). The upstream side (plunger 230 side) and downstream side (oil reservoir 223 side) of containment space 221 are connected by flow path 204. The cross-sectional area of ​​flow path 204 perpendicular to axis L is smaller than the cross-sectional area of ​​oil reservoir 223 perpendicular to axis L. When an external force is applied toward the side opposite to opening 221A, piston 201 slides in the direction of contraction of return spring S. This restricts the range of motion of piston 201 within containment space 221. In other words, piston 201 is positioned by supply plunger 230. In this manner, the supply plug 230 can realize the valve 200 including the slidable piston 201 with a small number of parts.

[0059] A flow path 233 is formed in the supply plug 230 . The flow path 233 is formed as a through hole that penetrates the supply plug 230 in the direction of the axis L. The flow path 233 includes an inlet 234 , an outlet 235 , and an intermediate portion 236 .

[0060] The inlet 234 is connected to the upstream side of the intermediate portion 236. The inlet 234 is formed to have a larger diameter than the diameter of the intermediate portion 236 (flow path cross-sectional area).

[0061] The outlet 235 is connected to the downstream side of the intermediate portion 236. The outlet 235 is formed with a diameter larger than that of the intermediate portion 236.

[0062] The intermediate portion 236 is formed to have a constant diameter along the direction of the axis L. The flow path 233 allows the working fluid to flow through the filter F to the flow path 204 .

[0063] Next, the operation of the valve 200 will be described.

[0064] The following description will describe the operation of the valve 200 when the working fluid flows from the outside of the supply plug 230 into the flow path 233 in the following cases: the viscosity of the working fluid is high at low temperatures, the proportional solenoid valve 170 is actuated suddenly, and the proportional solenoid valve 170 is switched on / off. Figure 4 As shown, the working fluid passing through flow path 233 experiences pressure loss as it circulates through filter F. In this case, there's a possibility that the working fluid may not fully pass through filter F and may stagnate in the filter F portion (inside filter F and upstream of top surface 203). Because the working fluid stagnates in the filter F portion, the pressure of the working fluid acting on the filter F portion increases. Consequently, piston 201 is pushed toward the downstream side of containment space 221 by the working fluid pressure exerted on the filter F portion.

[0065] like Figure 5 As shown, when the pressure of the working fluid applied to the filter F portion exceeds a predetermined value, piston 201 moves in the direction of the contraction of return spring S (from the upstream side of containment space 221 to the downstream side). As piston 201 moves, it discharges a volume of working fluid corresponding to the volume moved by piston 201 from oil reservoir 223 within containment space 221, through discharge port 206 to flow path 224. When the flow (e.g., viscosity, pressure, flow rate, etc.) of the working fluid flowing into flow path 233 returns to normal, the working fluid passes through filter F. As a result, the pressure of the working fluid applied to piston 201 (filter F portion) falls below a predetermined value. As a result, return spring S pushes piston 201 back toward supply plunger 230. The working fluid flows through filter F into cavity 201S and is discharged through discharge port 206. The working fluid discharged from discharge port 206 flows into flow path 224 on the downstream side. In this embodiment, the predetermined value is the resultant force of the return spring S and the force acting on the piston 201 (top surface 203) due to the pressure within the oil storage space 223. In other words, when the pressure applied to the filter portion F exceeds the resultant force, the piston 201 moves in the direction in which the return spring S contracts.

[0066] As described above, according to valve 200, even when pressure loss of the working fluid occurs in filter F due to an operation such as abruptly operating proportional solenoid valve 170, piston 201 moves, allowing the working fluid accumulated in oil reservoir 223 to flow into flow path 224. This allows the working fluid to be supplied to proportional solenoid valve 170 without stagnation, reducing response delay of proportional solenoid valve 170.

[0067] [Modification]

[0068] like Figure 6As shown, a bypass flow path 250 can also be provided in the valve 200. The bypass flow path 250 is connected near the top surface 203 of the piston 201 to the flow path 224. The bypass flow path 250 is a flow path different from the accommodation space 221. The bypass flow path 250 bypasses the oil storage space 223 and connects the upstream side of the accommodation space 221 and the flow path 224. The upstream end of the bypass flow path 250 is connected to a position in the accommodation space 221 that is upstream of the oil storage space 223. The upstream end of the bypass flow path 250 switches the connection and blockage with the accommodation space 221 as the piston 201 moves, using the top surface 203. The downstream end of the bypass flow path 250 is connected to the flow path 224. Another filter F1 different from the filter F is provided in the middle of the bypass flow path 250.

[0069] When the piston 201 moves, the top surface 203 moves downstream, so that the upstream end of the bypass flow path 250 opens at a position in the accommodation space 221 that is upstream of the oil storage space 223. Thus, the bypass flow path 250 and the flow path 233 are connected via the accommodation space 221. Then, the flow path 233 is connected to the downstream flow path 224 via the bypass flow path 250 in a shorter way (Japanese: short - circuit). Thus, the working fluid flows out from the flow path 233 to the flow path 224 via the bypass flow path 250. By using the valve 200 having the bypass flow path 250, in addition to supplying the working fluid accumulated in the oil storage space 223 to the downstream flow path 224, the working fluid is also supplied from the bypass flow path 250. As a result, the delay in the response of the proportional solenoid valve 170 can be reduced.

[0070] In addition, the present invention is not limited to the above - described embodiments. Within the scope not departing from the gist of the present invention, it includes embodiments obtained by applying various changes to the above - described embodiments. In the above - described embodiments, a hydraulic system in which the working fluid is hydraulic oil is illustrated, but it can also be that the valve of the embodiment is applicable not only to a hydraulic system operating using hydraulic pressure but also to a hydraulic system using alcohol, water, or fuel as the working fluid. In the above - described embodiments, a structure in which a step 222 is formed in a diameter - enlarged manner at a position corresponding to the discharge port 206 of the piston 201 is illustrated. As Figure 7 shown, the step 222 can also be formed on the outer peripheral side of the piston 201.

[0071] In the above - described embodiments, a structure in which the filter F is provided in the flow path 204 is described, but it can also be a structure without the filter F.

[0072] In the above embodiment, the upstream and downstream sides of the accommodating space 221 are connected via the flow path 204 formed in the top surface 203. However, the upstream and downstream sides of the accommodating space 221 may be connected via, for example, a gap between the housing 220 and the piston 201, or via another flow path.

[0073] In the above embodiment, piston 201 is described as including body 202 and discharge port 206. However, piston 201 only needs to include at least top surface 203 (pressure receiving portion) and may be configured without body 202 or discharge port 206.

Claims

1. A valve, wherein: The valve has: a housing having a receiving space for receiving a working fluid flowing from an upstream side to a downstream side; and a movable valve core accommodated in the accommodation space and having a pressure-receiving portion that receives the pressure of the working fluid stagnant on the upstream side in the accommodation space, wherein the movable valve core moves from the upstream side toward the downstream side in the accommodation space due to the pressure applied to the pressure-receiving portion, and discharges the working fluid on the downstream side in the accommodation space to the outside of the accommodation space; The movable valve core has: a flow path provided in the pressure receiving portion and allowing the working fluid to flow from the upstream side toward the downstream side; and A filter is provided in the flow path.

2. The valve according to claim 1, wherein The movable spool has a discharge port for discharging the working fluid.

3. The valve according to claim 1, wherein The valve has: a bypass flow path, different from the housing space, communicating with the upstream side relative to the pressure-receiving portion in the housing space when the movable valve element moves, so that the working fluid flows around the downstream side relative to the pressure-receiving portion in the housing space; as well as Another filter is provided in the bypass flow path.

4. The valve according to any one of claims 1 to 3, wherein The valve includes a plug that is inserted into the housing space and limits the range of movement of the movable valve element in the housing space.

5. A valve, wherein: The valve has: a housing having a receiving space for receiving a working fluid flowing from an upstream side to a downstream side; The movable valve element comprises: a pressure-receiving portion for receiving the pressure of the working fluid stagnant on the upstream side in the accommodation space; a discharge port for discharging the working fluid on the downstream side of the accommodation space to the outside of the accommodation space; and a flow path provided in the pressure-receiving portion for allowing the working fluid to flow from the upstream side to the downstream side. and a filter provided in the flow path, wherein the movable valve element moves from the upstream side toward the downstream side in the housing space due to the pressure applied to the pressure receiving portion, and discharges the working fluid to the outside of the housing space through the discharge port; as well as A plug is embedded in the receiving space to limit the movement range of the movable valve core in the receiving space.

6. A hydraulic system, wherein: The hydraulic system has: An engine as a driving source; a hydraulic pump driven by the engine to circulate a working fluid; a plurality of actuators that utilize the pressure of the working fluid to drive an operating object; a proportional solenoid valve that switches the actions of the plurality of actuators; a valve mounted on the upstream side of the proportional solenoid valve, comprising: a housing having a housing for accommodating the working fluid flowing from the upstream side to the downstream side; and a movable valve element having a pressure-receiving portion that receives pressure from the working fluid stagnant on the upstream side in the housing space, the movable valve element moving from the upstream side to the downstream side within the housing space due to pressure applied to the pressure-receiving portion, and discharging the working fluid on the downstream side of the housing space to the outside of the housing space; a tank storing the working fluid; and A relief valve for regulating the pressure of the working fluid, The movable valve core has: a flow path provided in the pressure receiving portion and allowing the working fluid to flow from the upstream side toward the downstream side; and A filter is provided in the flow path.

7. A construction machine, wherein: The construction machinery has: A hydraulic system comprising: an engine as a driving source; a hydraulic pump driven by the engine to circulate a working fluid; and a plurality of actuators that drive an operating object using the pressure of the working fluid. a proportional solenoid valve that switches the actions of the plurality of actuators; a valve that is installed on the upstream side of the proportional solenoid valve and comprises: a housing having a receiving space for accommodating the working fluid that flows from the upstream side to the downstream side; and a movable valve core having a pressure-receiving portion that receives the pressure of the working fluid that is stagnant on the upstream side in the receiving space, the movable valve core moving from the upstream side toward the downstream side in the receiving space due to the pressure applied to the pressure-receiving portion, and discharging the working fluid on the downstream side in the receiving space to the outside of the receiving space; a tank that stores the working fluid; and a relief valve for adjusting the pressure of the working fluid. a rotating body, which is moved by the hydraulic system; and a traveling body that supports the rotating body so as to be rotatable, and the traveling body is driven by the hydraulic system to travel, The movable valve core has: a flow path provided in the pressure receiving portion and allowing the working fluid to flow from the upstream side toward the downstream side; and A filter is provided in the flow path.

8. A movable valve core, wherein: The movable valve core is accommodated in a receiving space provided in a housing and accommodating a working fluid flowing from an upstream side to a downstream side. The movable valve core has a pressure-receiving portion that receives the pressure of the working fluid stagnant on the upstream side in the receiving space. The movable valve core moves from the upstream side to the downstream side in the receiving space due to the pressure applied to the pressure-receiving portion, and discharges the working fluid on the downstream side of the receiving space to the outside of the receiving space. The movable valve core has: a flow path provided in the pressure receiving portion and allowing the working fluid to flow from the upstream side toward the downstream side; as well as A filter is provided in the flow path.

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