Proportional solenoid valve and fluid pressure system

Abstract

A proportional solenoid valve and a fluid pressure system are provided. The proportional solenoid valve of the present invention includes a valve stem, an electric drive portion, and a detection portion. The valve stem has a first end, a second end on the opposite side from the first end, and a through-hole along an axial direction. In the valve stem, working oil from a pump port is supplied to the through-hole from the first end. The electric drive portion is provided on the second end side of the valve stem and drives the valve stem. The detection portion is provided on the electric drive portion and detects a pressure of the pump port.

Description

Technical Field

[0001] This invention relates to an automated proportional solenoid valve and fluid pressure system suitable for hydraulic control. Background Technology

[0002] Regarding hydraulic circuits used in construction machinery, fluid pressure systems with hydraulic circuits equipped with electrically controlled proportional solenoid valves are on the rise. A proportional solenoid valve, for example, includes: a solenoid; a rod driven by the solenoid; a valve stem pushed by the rod; and a return spring for returning the valve stem to its original position. The valve stem connects and disconnects various ports: a pilot flow path connected to the pump supplying working oil, an actuator port connected to the actuator that drives the pump, and a discharge port connected to a reservoir for storing return oil.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 04-036183 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] To electrically control a proportional solenoid valve, it is necessary to detect the pressure of the working oil. For example, the proportional solenoid valve described in Patent Document 1 has a discharge port, an actuator port, and a pilot port provided in a direction orthogonal to the movement direction of the valve stem. In a proportional solenoid valve with such a structure, when detecting the pressure at the actuator port and the pilot port, a pressure detection unit needs to be provided separately from the proportional solenoid valve.

[0008] A proportional solenoid valve with other structures has an actuator port along the direction of valve stem movement, and a discharge port and a pilot port are provided in a direction orthogonal to the direction of valve stem movement. In this type of proportional solenoid valve, the actuator port of the valve stem is opposite to the rod driven by the electric drive unit that drives the valve stem; therefore, the control pressure of the actuator port acts on the electric drive unit. Thus, the pressure at the actuator port can be detected at the electric drive unit. However, this type of proportional solenoid valve cannot detect the pressure at the pilot port, which serves as the initial pressure.

[0009] The purpose of this invention is to provide a proportional solenoid valve and fluid pressure system that can easily detect the pressure of the working oil supplied from the pump.

[0010] Solution for solving the problem

[0011] A proportional solenoid valve according to one embodiment of the present invention comprises: a valve stem having a first end, a second end located on the side opposite to the first end, and a through hole along the axial direction, wherein working oil from a pump port is supplied from the first end to the through hole in the valve stem; an electric drive unit disposed on the second end side of the valve stem to drive the valve stem; and a detection unit disposed on the electric drive unit to detect the pressure of the pump port.

[0012] According to the technical solution of the present invention, the pump port is connected to the through hole formed in the valve stem, and the detection unit detects the force applied to the valve stem, thereby enabling the detection of the pilot pressure of the working oil flowing through the pump port RP.

[0013] In one embodiment of the proportional solenoid valve of the present invention, the electric drive unit may include a rod that abuts against the second end of the valve stem and pushes the valve stem.

[0014] Alternatively, one embodiment of the present invention provides a proportional solenoid valve comprising: a housing housing the valve stem and having a valve stem bore; a discharge port extending radially toward the valve stem from the valve stem bore; and an actuator port extending radially toward the valve stem from the valve stem bore. Alternatively, the valve stem may have: a first flow path connecting the discharge port and the actuator port; and a second flow path connecting the pump port and the actuator port.

[0015] In a proportional solenoid valve according to one embodiment of the present invention, when the valve is in a neutral state not driven by the electric drive unit, the valve stem connects the discharge port and the actuator port, and blocks the pump port. Alternatively, when the valve is driven by the electric drive unit, the valve stem connects the pump port and the actuator port, and blocks the discharge port.

[0016] In a proportional solenoid valve according to one embodiment of the present invention, the detection unit may detect the force transmitted from the valve stem subjected to the pressure to the rod that pushes the valve stem.

[0017] In one embodiment of the proportional solenoid valve of the present invention, the electric drive unit may include a solenoid for electromagnetically driving the rod. Alternatively, the detection unit may be configured to detect the force generated in the rod of the valve stem that pushes and transmits the pressure.

[0018] In one embodiment of the proportional solenoid valve of the present invention, the electric drive unit may also include a housing for housing a rod that pushes the valve stem and the detection unit.

[0019] A fluid pressure system according to one embodiment of the present invention comprises: a fluid pressure pump that generates fluid pressure using a working fluid; a fluid pressure valve device that switches the output target of the working fluid; an actuator driven by the working fluid supplied from the fluid pressure valve device; and a proportional solenoid valve comprising: a valve stem having a first end, a second end located on a side opposite to the first end, and a through hole along an axial direction, wherein working oil from a pump port is supplied from the first end to the through hole in the valve stem; an electric drive unit disposed at the second end of the valve stem for driving the valve stem; and a detection unit disposed at the electric drive unit for detecting the pressure at the pump port.

[0020] The effects of the invention

[0021] According to the technical solution of the present invention, the pressure of the working oil supplied from the pump of the working oil can be easily detected. Attached Figure Description

[0022] Figure 1 This is a diagram showing the general structure of the construction machinery in an embodiment of the present invention.

[0023] Figure 2 This is a diagram showing the structure of the hydraulic system in an embodiment of the present invention.

[0024] Figure 3 This is a block diagram illustrating the structure related to the control of the proportional solenoid valve in an embodiment of the present invention.

[0025] Figure 4 This is a cross-sectional view showing the structure of the proportional solenoid valve in an embodiment of the present invention.

[0026] Figure 5 This is a perspective view showing the structure of the valve column in an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures

[0028] 1. Hydraulic system; 100. Construction machinery; 101. Rotating body; 102. Traveling body; 103. Driver's seat; 104. Boom; 105. Stick; 106. Bucket; 108. Operating unit; 120. Engine; 121. Output shaft; 130. Hydraulic pump; 140. Actuator; 150. Proportional solenoid valve; 151. Electric drive unit; 152. Electromagnetic coil; 153. Rod; 154. Housing; 155. Main body; 160. Tank; 170. Detection unit; 200. Control Control device; 300, relief valve; A, first piece; B, second piece; C, dividing surface; G, return spring; H, valve stem hole; H1, first through hole; H2, second through hole; H3, enlarged diameter section; H4, first annular chamber; H5, second annular chamber; HD, step; Q, piping; RA, actuator port; RD, discharge port; RP, pump port; S, valve stem; S3, protrusion; S4, step; S5, step; S6, second flow path; SH, through hole; SM, groove; SN, notch. Detailed Implementation

[0029] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0030] (Construction machinery)

[0031] like Figure 1 As shown, the construction machinery 100 is, for example, a hydraulic excavator. The construction machinery 100 includes a slewing body 101 and a traveling body 102. The slewing body 101 is rotatably mounted on the traveling body 102. A hydraulic system 1 is provided on the slewing body 101.

[0032] The slewing body 101 includes: a driver's seat 103 for an operator; a boom 104 having one end connected to the slewing body 101 in a swingable manner; a stick 105 having one end connected to the other end (top) of the boom 104 in a swingable manner; a bucket 106 connected to the other end (top) of the stick 105 in a swingable manner; and an operating unit 108 for operator use. Additionally, a hydraulic system 1 is provided within the slewing body 101. The slewing body 101, boom 104, stick 105, and bucket 106 are driven by working fluid supplied from this hydraulic system 1.

[0033] (Hydraulic system)

[0034] like Figure 2As shown, the hydraulic system 1 (fluid pressure system) includes: an engine 120 as a drive source; a hydraulic pump 130 driven by the engine 120; multiple actuators 140 that actuate various parts of the construction machinery 100; a control valve 500 that switches the operation of the multiple actuators 140; a proportional solenoid valve 150 that applies control pressure of the working fluid to the control valve 500; a tank 160 that stores the working fluid; a detection unit 170 that detects the hydraulic pressure; a control device 200 that adjusts the proportional solenoid valve 150; and a relief valve 300 for pressure adjustment. In this embodiment, working oil is used as the working fluid, but fluids other than working oil can also be used. Furthermore, the hydraulic system 1 can be applied not only to construction machinery but also to other devices that use working fluid to generate fluid pressure, such as hydraulic presses.

[0035] Engine 120 is an internal combustion engine that uses gasoline or diesel fuel. Engine 120 has an output shaft 121, which is connected to a hydraulic pump 130. A pipe Q is connected to the hydraulic pump 130. The hydraulic pump 130 (fluid pressure pump) generates fluid pressure using working fluid. The hydraulic pump 130 is driven by the output shaft 121 to allow working fluid to flow to the pipe Q. A control valve 500 and a proportional solenoid valve 150 are connected to the pipe Q.

[0036] In this embodiment, the engine 120 is used as the driving source for the working fluid. However, in addition to the engine 120, an electric motor that uses a power source such as a battery can also be used as the driving source. Alternatively, the engine 120 can also be used as a generator to charge a battery and use it as a power source.

[0037] Control valve 500 (fluid pressure valve device) switches the output of working fluid. Multiple actuators 140 are connected to control valve 500 via branch piping Q. Multiple control valves 500 are provided, and the hydraulic pressure of the working fluid flowing to piping Q is switched by the switching operation of the operating unit 108, thereby supplying working fluid to the multiple actuators 140. The multiple actuators 140 drive the rotary body 101, boom 104, stick 105, and bucket 106, etc. Relief valve 300 releases pressure when the pressure in the flow path exceeds a preset predetermined value in the hydraulic circuit of hydraulic system 1. Working fluid from hydraulic pump 130 is supplied to proportional solenoid valve 150 based on the amount operated by the operating unit 108.

[0038] like Figure 3 As shown, the control device 200 controls the proportional solenoid valve 150 according to the operation amount of the operation unit 108. The control device 200 generates a control signal corresponding to the operation amount of the operation unit 108. The proportional solenoid valve 150 controls the valve opening according to the control signal, adjusts the flow rate of the working oil supplied to the control valve 500 from the hydraulic pump 130, and drives the actuator 140.

[0039] A detection unit 170 for detecting pilot pressure is provided in the proportional solenoid valve 150. As described later, the detection unit 170 detects, for example, the pilot pressure of the working oil flowing at the pump port RP connected to the proportional solenoid valve 150. The detection value detected by the detection unit 170 is fed back to the control device 200. The control device 200 controls the proportional solenoid valve 150 based on the detection value detected by the detection unit 170.

[0040] like Figure 4 and Figure 5 As shown, the proportional solenoid valve 150 includes: an electrically driven part 151; a valve stem S driven by the electrically driven part 151; a body 155 housing the valve stem S; and a return spring G that restores the position of the moved valve stem S. The valve stem S has: a first end; a second end S2 (the other end S2 discussed later) located on the side opposite to the first end S1 (the other end S1 discussed later); and a through hole SH along the axial direction. In the valve stem S, working oil from the pump port RP is supplied from the first end S1 to the through hole SH.

[0041] The electric drive unit 151 includes, for example, an electromagnetic coil 152 (solenoid) as a drive source; a rod 153 driven by the electromagnetic coil 152; a detection unit 170; and a housing 154 as an outer casing. The housing 154 is formed to cover the opening of the valve stem hole H, which will be discussed later, formed in the main body 155.

[0042] The electromagnetic coil 152 is formed into a cylindrical shape by winding copper wire around an iron core. The electromagnetic coil 152 generates a magnetic field by passing an electric current through the copper wire. The rod 153 is formed into a rod shape from metal. The rod 153 is also referred to as a plunger. The rod 153 has a protrusion 153T that protrudes radially.

[0043] The rod 153 has one end 153A (first rod end) and another end 153B (second rod end). The other end S2 (second end) of the valve stem S abuts against the side of end 153A. The rod 153 abuts against the other end S2 of the valve stem S, which has an opening communicating with the pump port RP. The protrusion 153T is arranged such that it is offset towards the other end 153B relative to the neutral axis L of the solenoid coil 152 when viewed in axial section.

[0044] The rod 153 is configured to slide freely axially within the electromagnetic coil 152. When viewed from the axial cross-sectional direction of the electromagnetic coil 152, the rod 153, when the electromagnetic coil 152 is energized, is attracted by the magnetic field generated by the electromagnetic coil 152 and moves in a direction orthogonal to the neutral axis L of the electromagnetic coil 152. At this time, the rod 153 pushes the other end S2 of the valve stem S. The electromagnetic coil 152 proportionally controls the amount of current applied according to the operation amount of the operating unit 108, adjusting the protrusion amount of the rod 153.

[0045] The valve stem S is movably housed in the valve stem hole H formed in the main body 155. The main body 155 is the outer casing constituting the hydraulic system 1 and has the valve stem hole H. Alternatively, the main body 155 can also be formed by machining an outer casing (not shown) constituting the hydraulic system 1. Alternatively, the main body 155 can be formed separately from the outer casing and fixed to it. The main body 155 is formed, for example, from two separate blocks, a first block A and a second block B. A dividing surface C is formed between the first block A and the second block B. The first block A is disposed on the other end S2 side of the valve stem S. The second block B is disposed on one end S1 (first end) side of the valve stem S.

[0046] A cylindrical valve stem hole H is formed in the main body 155. The valve stem hole H is formed as a through hole with a first diameter d1. The valve stem hole H has a first through hole H1 and a second through hole H2 with a first diameter d1, an enlarged portion H3 with a second diameter d2 that is larger than the first diameter d1, and a first annular chamber H4 and a second annular chamber H5 with a third diameter d3 that is larger than the second diameter d2.

[0047] The valve stem hole H is composed of a first through hole H1, a first annular chamber H4, an enlarged diameter section H3, a second annular chamber H5, and a second through hole H2, arranged in a sequence from the position where the electric drive section 151 is located towards opposite sides. The valve stem hole H is formed such that the opening on the first block A side of the valve stem hole H has a first diameter d1. In the valve stem hole H, a step HD is formed in the opening on the second block B side, and the valve stem hole H is formed such that it has a fourth diameter d4 that is smaller than the first diameter d1. A return spring G is inserted into the step of the opening on the second block B side. The return spring G is an elastic member such as a coil spring.

[0048] The opening on side B of the second block forms the pump port RP, which will be discussed later. In the first block A, a discharge port RD is formed in the valve stem hole H, which is connected to the flow path communicating with the tank 160. The discharge port RD is formed in a manner that extends radially outward toward the valve stem hole H. The discharge port RD is formed in a direction orthogonal to the axial direction of the valve stem hole H. At the connection between the discharge port RD and the valve stem hole H, a first annular chamber H4 that is radially enlarged in the valve stem hole H is formed.

[0049] The first annular chamber H4 is formed with a third diameter d3 that is larger than the second diameter d2. The discharge port RD is connected to the first annular chamber H4 on the side near the dividing surface C. The first annular chamber H4 is formed with a diameter larger than the diameter of the protrusion S3 of the valve stem S, which will be discussed later. The first annular chamber H4 accommodates the portion of the protrusion S3 on the side near the step S4, which will be discussed later. The enlarged diameter portion H3 accommodates the protrusion S3 of the valve stem S.

[0050] In section 2B, an actuator port RA is formed in the valve stem bore H in an extending manner, connecting to a flow path communicating with the actuator 140. The actuator port RA is formed in a radially outward direction toward the valve stem bore H. The actuator port RA is formed in a direction orthogonal to the axial direction of the valve stem bore H. A second annular chamber H5, which is radially enlarged, is formed at the connection portion between the actuator port RA and the valve stem bore H.

[0051] The second annular chamber H5 is formed with a third diameter d3 that is larger than the second diameter d2. The actuator port RA is connected to the second annular chamber H5 on the side near the dividing surface C. The second annular chamber H5 houses the portion of the protrusion S3 on the side near the step S5, which will be discussed later.

[0052] The valve stem S is formed into a rod shape, for example, from metal. A through hole SH is formed in the axial direction of the valve stem S. The through hole SH communicates with the pump port RP, which supplies working oil from the pump, at one end S1 of the valve stem S.

[0053] A return spring G is placed between one end of the valve stem S and the step HD of the valve stem hole H. The return spring G pushes the valve stem S toward the electric drive unit 151. One end 153A of the rod 153 of the electric drive unit 151 abuts against the other end S2 of the valve stem S. A groove SM is formed on the other end S2 opposite to the through hole SH. The groove SM is, for example, formed with a semi-circular cross section. The groove SM prevents the opening formed in the through hole SH at the other end S2 from being blocked when the end 153A of the rod 153 abuts against it. The valve stem S has a protrusion S3 formed in the axial direction with its diameter increasing radially.

[0054] A protrusion S3 is formed between one end S1 and the other end S2. The protrusion S3 has a step S4 on the other end S2 side. Pressure from the discharge port RD acts on the step S4. The protrusion S3 has a step S5 on the one end S1 side. Pressure from the actuator port RA acts on the step S5. The protrusion S3 has a notch SN (first flow path) formed as a groove along the axial direction. The notch SN has a closed end SN1 on the step S4 side that does not communicate with the step S4. The notch SN has an open end SN2 on the step S5 side that communicates with the step S5.

[0055] A second flow path S6 communicating with the through hole SH is formed in the protrusion S3. The second flow path S6 is formed in a direction orthogonal to the through hole SH. There is one second flow path S6 in the direction opposite to the notch SN, and two second flow paths S6 are formed in the direction orthogonal to the notch SN.

[0056] When the electric drive unit 151 is not driven (in a neutral state) Figure 4(As shown on the left), the valve stem S connects the first annular chamber H4 and the second annular chamber H5. In this state, the closed end SN1 of the notch SN is located inside the first annular chamber H4, and the open end SN2 is located inside the second annular chamber H5. The notch SN connects the first annular chamber H4 and the second annular chamber H5. That is, when the valve stem S is neutral, it connects the discharge port RD and the actuator port RA via the notch SN.

[0057] In this state, the valve stem S blocks the pump port RP and the second annular chamber H5. In this state, the second flow path S6 is housed within the expansion section H3, and the opening of the second flow path S6 is blocked by the wall of the expansion section H3. That is, the valve stem S blocks the discharge port RD and the actuator port RA relative to the pump port RP.

[0058] The working fluid flowing in from the pump port RP flows through the through hole SH and flows out from the groove SM formed between the other end S2 of the valve stem S and one end 153A of the rod 153, filling the housing 154 of the electric drive unit 151 and generating hydraulic pressure. The detection unit 170 detects the pressure (pilot pressure) of the working fluid in the housing 154.

[0059] When driven by the electric drive unit 151 ( Figure 4 (As shown on the right), lever 153 pushes valve stem S, causing valve stem S to move in the direction of shortening return spring G. The size of the opening in the second flow path S6 that communicates with the second annular chamber H5 increases according to the amount of movement of valve stem S. This connects pump port RP to the second annular chamber H5, adjusting the flow rate of the working oil. Valve stem S connects pump port RP and actuator port RA, and also adjusts the flow rate of the working oil.

[0060] At this time, the working fluid flowing in from the pump port RP flows through the second flow path S6 and the second annular chamber H5 from the pump port RP and flows out to the actuator port RA. The pressure of the working fluid (pilot pressure) inside the housing 154 is lower than when the electric drive unit 151 is not driven and is in a neutral state. The detection unit 170 detects the pressure of the working fluid inside the housing 154.

[0061] If the movement of the valve stem S ends, the closed end SN1 of the notch SN is housed in the expanded diameter section H3. Therefore, the first annular chamber H4 and the second annular chamber H5 are blocked. That is, the valve stem S blocks the discharge port RD and the actuator port RA.

[0062] With the valve stem S in the aforementioned state, the detection unit 170 detects the force transmitted from the other end S2 of the valve stem S to the rod 153. The pressure of the working oil supplied from the pump port RP acts on one end S1 of the valve stem S. Therefore, the detection unit 170 inside the housing 154 can directly detect the pressure (pilot pressure) of the pump port RP based on the amount of movement of the valve stem S.

[0063] As described above, according to the proportional solenoid valve 150, the pump port RP is connected to the through hole SH formed in the valve stem S. Furthermore, the detection unit 170 detects the force applied to the rod 153 that abuts against the valve stem S, thereby enabling the detection of the pressure (pilot pressure) of the working oil flowing through the pump port RP based on the amount of movement of the valve stem S. In other words, according to the proportional solenoid valve 150, the detection unit 170 detects the pressure applied in the movement direction to the valve stem S connected to the pump port RP, thus simplifying the structure of the device for detecting the pilot pressure.

[0064] Furthermore, the present invention is not limited to the embodiments described above, and includes embodiments with various modifications made to the above embodiments without departing from the spirit of the invention. For example, in the above embodiments, the main body 155 is illustrated as being divided into two parts to form a first block A and a second block B, but it is not limited thereto, and the main body 155 may also be formed into three parts.

Claims

1. A proportional solenoid valve, wherein, This proportional solenoid valve has the following features: A valve stem having a first end, a second end located on the side opposite to the first end, and a through hole along the axial direction, wherein working oil from a pump port is supplied from the first end to the through hole; An electric drive unit is disposed at the second end of the valve stem and drives the valve stem; A detection unit, which is disposed in the electric drive unit, detects the pressure at the pump port; A housing that houses the valve stem and has a valve stem bore; A discharge port that extends radially toward the valve stem bore; as well as Actuator port, which extends radially from the valve stem bore toward the valve stem. The valve stem has: A first flow path, which connects the discharge port and the actuator port; and The second flow path connects the pump port and the actuator port via the through hole.

2. The proportional solenoid valve according to claim 1, wherein, The electric drive unit includes a rod that abuts against the second end of the valve stem to push the valve stem.

3. The proportional solenoid valve according to claim 1, wherein, In the neutral state, not driven by the electric drive unit, the valve stem connects the discharge port and the actuator port, and blocks the pump port. When driven by the electric drive unit, the valve stem connects the pump port and the actuator port, and blocks the discharge port.

4. The proportional solenoid valve according to claim 1, wherein, The detection unit detects the force transmitted from the valve stem subjected to the pressure to the rod that pushes the valve stem.

5. The proportional solenoid valve according to claim 1, wherein, The electric drive unit includes a housing that houses the rod that pushes the valve stem and the detection unit.

6. A fluid pressure system, wherein, This fluid pressure system has the following features: A fluid pressure pump uses a working fluid to generate fluid pressure. A fluid pressure valve device that switches the output of the working fluid; An actuator driven by the working fluid supplied from the fluid pressure valve device; as well as A proportional solenoid valve comprising: a valve stem having a first end, a second end located on the side opposite to the first end, and a through hole along the axial direction, wherein working oil from a pump port is supplied from the first end to the through hole in the valve stem; An electric drive unit is disposed at the second end of the valve stem and drives the valve stem; A detection unit, disposed in the electric drive unit, detects the pressure at the pump port; a housing, which accommodates the valve stem and has a valve stem hole; A discharge port extending radially from the valve stem bore toward the valve stem; and an actuator port extending radially from the valve stem bore toward the valve stem. The valve stem has: A first flow path, which connects the discharge port and the actuator port; and The second flow path connects the pump port and the actuator port via the through hole.

Images