Electric spool valve and poppet valve device having same

Abstract

This electric spool valve comprises: a housing including a spool hole, an inlet-side flow path, and an outlet-side flow path; a spool for opening / closing between the inlet-side flow path and the outlet-side flow path; and an electric apparatus for causing the spool to stroke. The spool hole includes a communication hole portion and an inlet-side connection hole portion that is disposed on one side in an axial direction from the communication hole portion and connected to the inlet-side flow path. The spool includes a shaft portion and an inlet-side land portion that is disposed in the inlet-side connection hole portion and that has a diameter larger than that of the shaft portion and smaller than that of the inlet-side connection hole portion. The inlet-side land portion has a notch, and an end portion thereof on the other side in the axial direction is fitted into the communication hole portion to close between the inlet-side flow path and the outlet-side flow path. The notch is formed in the end portion on the other side in the axial direction of the inlet-side land portion, and is located on the other side in the axial direction from the inlet-side flow path in a state in which the spool is fully stroked to the one side in the axial direction.

Description

Electric spool valve and poppet valve device equipped with same

[0001] The present disclosure relates to an electric spool valve in which a spool is stroked by an electric device, and a poppet valve device including the same.

[0002] A known example of a spool valve is the pilot valve disclosed in Patent Document 1. The pilot valve disclosed in Patent Document 1 is a pilot pressure-driven spool valve, and the spool is stroked by pilot pressure output from a proportional valve.

[0003] Japanese Patent Application Laid-Open No. 2022-166300

[0004] For spool valves, cost reduction and increased layout flexibility are desired. Therefore, there is a demand for the development of electric spool valves equipped with electric devices such as solenoids and direct-acting motors instead of proportional valves. However, the driving force of the electric devices in electric spool valves is small. Therefore, electric spool valves are likely to be affected by fluid forces acting on the spool when moving it.

[0005] Therefore, an object of the present disclosure is to provide an electric spool valve that can reduce the influence of fluid forces acting on the spool.

[0006] The electric spool valve of the present disclosure includes a housing including a spool hole extending in an axial direction, an inlet-side flow path connected to the spool hole, and an outlet-side flow path connected to the spool hole; a spool that is slidably inserted into the spool hole and opens and closes the space between the inlet-side flow path and the outlet-side flow path by stroking; and an electric device that strokes the spool, wherein the spool hole includes a communication hole portion and an inlet-side connecting hole portion that is located on one axial side of the communication hole portion and is connected to the inlet-side flow path, and the spool has a spool hole that is slidably inserted into the spool hole and .... the inlet-side land portion has a notch, and an end portion on the other axial side is fitted into the communicating hole portion to close the gap between the inlet-side flow path and the outlet-side flow path; the notch is formed in the end portion on the other axial side of the inlet-side land portion, and is located on the other axial side of the inlet-side flow path when the spool is fully stroked in the one axial direction.

[0007] According to the present disclosure, the notch is formed at the end of the inlet-side land portion on the other axial side. The notch is located on the other axial side of the inlet-side flow passage when the spool is fully axially moved in one direction. Therefore, the pilot fluid can be prevented from flowing directly into the notch after flowing from the inlet-side flow passage into the inlet-side connection hole. Therefore, the pilot fluid flows into the notch after being rectified around the spool. This can suppress pressure fluctuations of the pilot fluid in the notch. This can suppress fluctuations in fluid force acting on the spool. This can reduce the effect of fluid force on the spool.

[0008] The poppet valve device of the present disclosure includes the aforementioned electric spool valve and a poppet valve that adjusts the opening of the flow path in accordance with the pilot pressure, and the electric spool valve adjusts the pilot pressure by stroking the spool.

[0009] According to the present disclosure, it is possible to realize a poppet valve device having the above-described functions, which allows the poppet valve device to be controlled with higher precision.

[0010] According to the present disclosure, the influence of fluid forces acting on the spool can be reduced.

[0011] The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings.

[0012] Fig. 4 is a cross-sectional view showing a poppet valve device of the present embodiment; Fig. 5 is an enlarged cross-sectional view showing a poppet valve provided in the poppet valve device of Fig. 1; Fig. 6 is an enlarged cross-sectional view showing an electric pilot valve provided in the poppet valve device of Fig. 1; Fig. 7 is an enlarged cross-sectional view showing a spool of the electric pilot valve of Fig. 2 on a further enlarged scale; Fig. 8 is an enlarged cross-sectional view showing a spool in a closed position in the electric pilot valve of Fig. 4; Fig. 9 is an enlarged cross-sectional view showing an electric pilot valve of another embodiment;

[0013] A poppet valve device 1 and an electric pilot valve 2 provided therein according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the concepts of directions used in the following description are used for convenience of explanation and do not limit the orientation of the configuration of the present invention to those directions. Furthermore, the poppet valve device 1 and the electric pilot valve 2 described below are merely one embodiment of the present disclosure. Therefore, the present disclosure is not limited to the embodiment, and additions, deletions, and modifications are possible within the scope of the invention.

[0014] 1 controls the flow rate of hydraulic fluid in accordance with the energization state (e.g., current or voltage). The poppet valve device 1 is provided in a construction machine such as a shovel. The poppet valve device 1 controls the flow rate of hydraulic fluid flowing to a hydraulic actuator provided in the construction machine in accordance with the energization state. The poppet valve device 1 includes, for example, a valve block 3, a poppet valve 4, and an electric pilot valve 2.

[0015] [Valve Block] The valve block 3 is provided with a poppet valve 4 and an electric pilot valve 2. More specifically, the valve block 3 has a valve space 11 and a flow path 12. The valve space 11 is a bottomed hole extending along a predetermined axis L1. The valve space 11 accommodates a poppet valve 4, which will be described in detail later. The flow path 12 is formed in the valve block 3 so as to interpose the valve space 11 therebetween. More specifically, the flow path 12 includes a primary side portion 12a and a secondary side portion 12b. The primary side portion 12a has a valve port 11a that opens at the bottom surface of the valve space 11 and is connected to the valve space 11 via the valve port 11a. A valve seat 11b is formed at the bottom surface of the valve space 11 so as to surround the valve port 11a. On the other hand, the secondary side portion 12b opens at the inner circumferential surface of the bottom portion of the valve space 11 and is connected to the valve space 11. In this way, the primary side portion 12 a and the secondary side portion 12 b are each connected to the valve space 11 and are connected to each other via the valve space 11 .

[0016] [Poppet Valve] The poppet valve 4 is provided in the valve block 3. More specifically, the poppet valve 4 is housed in the valve space 11 and provided in the valve block 3 so as to be interposed in the flow path 12. The poppet valve 4 also adjusts its opening degree in response to the pilot pressure. In this way, the poppet valve 4 adjusts the flow rate of the working fluid flowing through the flow path 12 in response to the pilot pressure. More specifically, the poppet valve 4 includes a main valve element 14, a check valve element 15, and a main valve spring member 16, as shown in FIG. 2 .

[0017] The main valve element 14 is slidably housed in the valve space 11. More specifically, the main valve element 14 is housed in the valve space 11 so as to be slidable in a first direction in which the axis L1 extends. When the main valve element 14 moves in one direction in the first direction, its tip portion seats on the valve seat 11b, closing the valve port 11a (see FIG. 1). When the main valve element 14 moves in the other direction in the first direction, it moves away from the valve seat 11b, opening the valve port 11a (see FIG. 2). The opening degree of the valve port 11a is adjusted according to the position of the main valve element 14. In this way, the main valve element 14 opens and closes the valve port 11a, and adjusts the opening degree of the valve port 11a according to its position.

[0018] The main valve element 14 also forms a pilot chamber 11c in the valve space 11. Explaining in more detail, in the valve space 11, the pilot chamber 11c is formed on the opposite side of the valve port 11a in the first direction across the main valve element 14. Pilot fluid is introduced into the pilot chamber 11c. The main valve element 14 receives the pressure of the pilot fluid, i.e., pilot pressure, in one direction.

[0019] Furthermore, the main valve element 14 includes a feedback passage 14a. The feedback passage 14a guides the pilot fluid from the primary side portion 12a to the pilot chamber 11c. In this embodiment, the feedback passage 14a has an internal passage portion 14b and a side notch 14c.

[0020] The internal passage 14b is formed inside the main valve element 14 and is connected to the primary side portion 12a. More specifically, the tip of the main valve element 14 protrudes from the valve seat 11b toward the primary side portion 12a, and the internal passage 14b opens to the primary side portion 12a at the tip of the main valve element 14. Hydraulic fluid is guided to the internal passage 14b via an opening 14d. The side notch 14c is formed in the middle portion of the outer circumferential surface of the main valve element 14 and is connected to the internal passage 14b. The valve block 3 also has an annular passage 11d formed in the valve space 11. The annular passage 11d is formed in the middle portion of the inner circumferential surface of the valve space 11 in the first direction. More specifically, the annular passage 11d is positioned corresponding to the side notch 14c. The side notch 14c is connected to the pilot chamber 11c via the annular passage 11d. In this way, the feedback flow path 14a connects the primary side portion 12a and the pilot chamber 11c via the annular passage portion 11d, and guides the pilot liquid from the primary side portion 12a to the pilot chamber 11c.

[0021] The check valve element 15 opens and closes the feedback flow path 14a. More specifically, the check valve element 15 is provided within the main valve element 14 so as to be interposed in the feedback flow path 14a. The check valve element 15 is slidably provided within the main valve element 14. The check valve element 15 closes the feedback flow path 14a by seating on a check valve seat 14f formed within the main valve element 14 (see FIG. 1), and opens the feedback flow path 14a by moving away from the check valve seat 14f (see FIG. 2). Furthermore, the check valve element 15 receives the hydraulic pressure of the hydraulic fluid flowing from the primary side portion 12a to the pilot chamber 11c, and is urged toward the check valve seat 14f against this hydraulic pressure. This allows the hydraulic fluid to flow from the primary side portion 12a to the pilot chamber 11c and prevents the flow of hydraulic fluid in the reverse direction.

[0022] The main valve spring member 16 biases the main valve element 14 in the closing direction. More specifically, the main valve spring member 16 is a compression coil spring. The main valve spring member 16 is accommodated in a compressed state in the pilot chamber 11c. In this embodiment, the pilot chamber 11c is blocked by a housing 21, which will be described in detail later. The main valve spring member 16 abuts against the housing 21 and the main valve element 14, and is accommodated in the pilot chamber 11c in a compressed state. As a result, the main valve element 14 is biased in one of the first directions, i.e., toward the valve seat 11b.

[0023] [Electric Pilot Valve] The electric pilot valve 2, which is an example of an electric spool valve, is provided in the valve block 3 as shown in FIG. 3 . More specifically, the electric pilot valve 2 is provided in the valve block 3 so as to block the valve space 11 (more specifically, the pilot chamber 11c). The electric pilot valve 2 is energizable, and its opening degree is adjusted depending on the energization state. In this embodiment, the electric pilot valve 2 discharges pilot fluid from the pilot chamber 11c and adjusts the fluid pressure in the pilot chamber 11c, i.e., the pilot pressure, by changing the opening degree depending on the energization state so as to discharge the pilot fluid. The electric pilot valve 2 configured in this manner includes a housing 21, a spool 22, an electric device 23, and a spring member 24.

[0024] The housing 21 is provided in the valve block 3. More specifically, the housing 21 is provided in the valve block 3 so as to close the valve space 11 (more specifically, the pilot chamber 11c). As shown in FIG. 4 , the housing 21 has a spool hole 31, an inlet-side flow path 32, and an outlet-side flow path 33.

[0025] The spool hole 31 extends in a second direction in the housing 21. The second direction, which is an example of an axial direction, is, for example, a direction perpendicular to the first direction. More specifically, the spool hole 31 has a circular cross section and penetrates the housing 21 in the second direction so that its axis L2 extends in the second direction. One side of the spool hole 31 in the second direction is blocked by the spring receiving portion 25, and the other side in the second direction is blocked by the electric device 23. The spool hole 31 has a communication hole portion 31a, an inlet-side connection hole portion 31b, and an outlet-side connection hole portion 31c. More specifically, the spool hole 31 further has two slide holes 31d and 31e, a spring accommodating portion 31f, and an insertion hole portion 31g.

[0026] The communication hole 31a is located in the middle of the spool hole 31. More specifically, the communication hole 31a is located between the inlet-side connection hole 31b and the outlet-side connection hole 31c, which will be described in detail later. The communication hole 31a is formed, for example, with a circular cross section.

[0027] The inlet-side connection hole 31b is located on one side of the communicating hole 31a in the second direction. More specifically, the inlet-side connection hole 31b is located on one side of the communicating hole 31a in the second direction so as to be adjacent to the communicating hole 31a. The inlet-side connection hole 31b has a larger diameter than the communicating hole 31a. The inlet-side connection hole 31b is connected to the inlet-side flow path 32, which will be described later.

[0028] The outlet-side connection hole 31c is located on the other side of the communicating hole 31a in the second direction. More specifically, the inlet-side connection hole 31b is located on the other side of the communicating hole 31a in the second direction so as to be adjacent to the communicating hole 31a. The outlet-side connection hole 31c is also formed with a larger diameter than the communicating hole 31a. On the other hand, the outlet-side connection hole 31c is formed with a larger diameter than the inlet-side connection hole 31b. The outlet-side connection hole 31c does not necessarily have to be larger in diameter than the inlet-side connection hole 31b, but may be the same diameter as or smaller than the inlet-side connection hole 31b. The outlet-side connection hole 31c is also connected to the outlet-side flow path 33, which will be described later.

[0029] The two slide holes 31d, 31e are located on the opposite side of the communication hole 31a from the inlet-side connection hole 31b and the outlet-side connection hole 31c. That is, the inlet-side slide hole 31d is located on one side of the inlet-side connection hole 31b in the second direction, and the outlet-side slide hole 31e is located on the other side of the outlet-side connection hole 31c in the second direction. The two slide holes 31d, 31e are located adjacent to the inlet-side connection hole 31b and the outlet-side connection hole 31c, respectively. The two slide holes 31d, 31e are formed with the same diameter as the communication hole 31a, for example. Note that the two slide holes 31d, 31e may be formed with a larger or smaller diameter than the communication hole 31a.

[0030] The spring accommodating portion 31f is located on one side of the inlet-side connecting hole 31b in the second direction. More specifically, the spring accommodating portion 31f is located on one side of the inlet-side sliding hole 31d in the second direction so as to be adjacent to the inlet-side sliding hole 31d. The spring accommodating portion 31f has a larger diameter than the inlet-side connecting hole 31b, for example. The spring accommodating portion 31f opens on one side of the housing 21 in the second direction, and this opening is blocked by the spring receiving portion 25. In this embodiment, the spring accommodating portion 31f is connected to the tank passage 34 and further connected to a tank (not shown) via the tank passage 34.

[0031] The insertion hole 31g is located on the other side in the second direction of the outlet-side sliding hole 31e. More specifically, the insertion hole 31g is located on the other side in the second direction of the outlet-side sliding hole 31e so as to be adjacent to the outlet-side sliding hole 31e. The insertion hole 31g opens on the other side in the second direction in the housing 21. The electric device 23, which will be described in detail later, is attached to the housing 21 in a manner that closes the opening of the insertion hole 31g.

[0032] The inlet-side flow passage 32 is connected to the spool hole 31. More specifically, as described above, the inlet-side flow passage 32 is connected to the inlet-side connecting hole 31b of the spool hole 31. In this embodiment, the inlet-side flow passage 32 has an inlet-side opening 32a that opens on the inner circumferential surface of the inlet-side connecting hole 31b, and is connected to the inlet-side connecting hole 31b via the inlet-side opening 32a. The inlet-side flow passage 32 also extends radially outward from the inlet-side connecting hole 31b, perpendicular to the second direction. The inlet-side flow passage 32 is connected to the pilot chamber 11c. Therefore, the inlet-side flow passage 32 connects the inlet-side connecting hole 31b and the pilot chamber 11c.

[0033] The outlet-side flow passage 33 is connected to the spool hole 31. The outlet-side flow passage 33 is connected to the spool hole 31, for example, away from the inlet-side flow passage 32 on one side in the second direction. More specifically, as described above, the outlet-side flow passage 33 is connected to the outlet-side connecting hole 31c of the spool hole 31. In this embodiment, the outlet-side flow passage 33 also has an outlet-side opening 33a that opens on the inner circumferential surface of the outlet-side connecting hole 31c and is connected to the outlet-side connecting hole 31c via the outlet-side opening 33a. The outlet-side flow passage 33 is also inclined radially outward, moving away from the inlet-side flow passage 32. The outlet-side flow passage 33 is connected to the secondary-side portion 12b of the flow passage 12. More specifically, the valve block 3 has a connecting passage 3a, and the outlet-side flow passage 33 is connected to the secondary-side portion 12b via the connecting passage 3a.

[0034] [Spool] The spool 22 is slidably inserted into the spool bore 31 with its axis extending in the second direction. More specifically, the spool 22 is formed, for example, in a cylindrical shape and slidably inserted into the communication hole 31a of the spool bore 31. The spool 22 closes the communication between the inlet-side flow path 32 and the outlet-side flow path 33 by stroking. More specifically, the spool 22 changes its position by stroking between a closed position that closes the communication between the inlet-side flow path 32 and the outlet-side flow path 33 and an open position that communicates the communication between the inlet-side flow path 32 and the outlet-side flow path 33. In the open position, the spool 22 adjusts the communication between the inlet-side flow path 32 and the outlet-side flow path 33 to an opening degree corresponding to the stroke amount. In this embodiment, the spool 22 has a shaft portion 22a, an inlet-side land portion 22b, and an outlet-side land portion 22c. The spool 22 also has a catch mounting portion 22d.

[0035] The shaft portion 22a is inserted through the communication hole portion 31a. More specifically, the shaft portion 22a is inserted through the communication hole portion 31a in the open position as shown in FIG. 3 . The shaft portion 22a is formed, for example, in a cylindrical shape. The outer diameter of the shaft portion 22a is smaller than the diameter of the communication hole portion 31a. Therefore, in the open position, the shaft portion 22a is the communication hole portion 31a, and forms the communication portion 28 around the shaft portion 22a.

[0036] The inlet-side land 22b is located on one axial side of the shaft portion 22a. In this embodiment, the inlet-side land 22b is integrally formed on one axial end face of the shaft portion 22a, i.e., on one end face. The inlet-side land 22b is located in the inlet-side connection hole 31b. The inlet-side land 22b has a smaller diameter than the inlet-side connection hole 31b. Therefore, the inlet-side land 22b forms an inlet-side annular flow path 27 between itself and the inner circumferential surface of the inlet-side connection hole 31b.

[0037] The inlet-side land portion 22b has a larger diameter than the shaft portion 22a, and the outer diameter of the inlet-side land portion 22b matches the diameter of the communicating hole 31a. Therefore, the inlet-side land portion 22b fits into the communicating hole 31a, and in the closed position, the end portion on the other side in the second direction (hereinafter simply referred to as the "other end") fits into the communicating hole 31a to close the gap between the inlet-side flow path 32 and the outlet-side flow path 33. The outer diameter of the inlet-side land portion 22b matches the diameter of the inlet-side sliding hole 31d, and the portion of the inlet-side land portion 22b on one side in the second direction is slidably fitted into the inlet-side sliding hole 31d.

[0038] The inlet-side land 22b also has at least one notch 22e. In this embodiment, the inlet-side land 22b has four notches 22e. The four notches 22e are formed at the other end of the inlet-side land 22b. More specifically, the four notches 22e are arranged at equal intervals in the circumferential direction on the outer peripheral surface of the other end of the inlet-side land 22b. The notches 22e extend from the other end face to one side in the second direction on the outer peripheral surface of the inlet-side land 22b. The notches 22e are arranged as follows:

[0039] That is, in the closed position shown in Fig. 5, the entire notch 22e is positioned in and blocked by the communication hole 31a. On the other hand, as the spool 22 strokes from the closed position to the open position, the notch 22e gradually opens from the tip side to the inlet-side connection hole 31b. That is, as the spool 22 strokes from the closed position to the open position, the notch 22e connects the inlet-side connection hole 31b and the communication hole 31a with an opening degree that corresponds to the stroke. This allows the spool 22 to flow a minute flow rate of pilot fluid from the inlet-side connection hole 31b to the communication hole 31a.

[0040] Furthermore, as will be described in detail later, the notch 22e is located on the other side of the inlet-side opening 32a in the second direction when the spool 22 is fully stroked in one direction in the second direction (i.e., fully stroked in the open position, hereinafter referred to as the "full stroke state"). More specifically, the tip of the notch 22e, i.e., one end of the notch 22e, is spaced a distance A away from the inlet-side opening 32a in the other axial direction. In this embodiment, in the full stroke state, the notch 22e is located on the other side of the second direction from a projection 22g (see the cross-hatched portion in FIG. 4 ) formed by extending the inlet-side flow path 32 and projecting it onto the inlet-side land portion 22b. The notch 22e thus positioned is not located on the one side of the inlet-side opening 32a in the open position.

[0041] Furthermore, the notch 22e is, for example, a tapered notch, and the tip portion of the bottom surface is tapered. That is, the tip portion of the bottom surface of the notch 22e is inclined radially outward as it progresses toward one side in the second direction. In this embodiment, the taper angle α of the bottom surface of the notch 22e is 15 degrees or more and 40 degrees or less with respect to the axis L2. Note that the notch 22e may be a notch other than a tapered notch, for example, one whose bottom surface extends straight in the second direction.

[0042] The outlet-side land portion 22c is located on the other side in the second direction relative to the shaft portion 22a. In this embodiment, the outlet-side land portion 22c is integrally formed on the other end surface of the shaft portion 22a, which is the end surface on the other side in the second direction. The outlet-side land portion 22c is formed with a larger diameter than the shaft portion 22a. The outer diameter of the outlet-side land portion 22c matches the diameter of the outlet-side slide hole 31e, and the portion of the outlet-side land portion 22c on the other side in the second direction is slidably fitted into the outlet-side slide hole 31e. One end of the outlet-side land portion 22c is located in the outlet-side connection hole 31c, as shown in FIG. 5 . More specifically, in the closed position, one end of the outlet-side land portion 22c is located in the outlet-side connection hole 31c. More specifically, one end of the outlet-side land portion 22c protrudes a distance B from the outlet-side slide hole 31e toward the outlet-side opening 33a.

[0043] Furthermore, one end surface of the outlet-side land portion 22c has an inclined portion 22f. The inclined portion 22f is formed at least on the outer circumferential edge of the one end surface of the outlet-side land portion 22c. In this embodiment, the inclined portion 22f is formed all around the shaft portion 22a on the one end surface of the outlet-side land portion 22c. That is, the inclined portion 22f is inclined so as to lean toward the other side in the second direction as it extends from the shaft portion 22a toward the outer circumferential edge of the outlet-side land portion 22c on the one end surface of the outlet-side land portion 22c. In this embodiment, the inclined portion 22f is inclined by an inclination angle β with respect to the axis L2. The inclination angle β is, for example, greater than or equal to 60 degrees and less than or equal to 85 degrees.

[0044] The catch mounting portion 22d is located further to one side of the inlet-side land portion 22b in the second direction. More specifically, the catch mounting portion 22d is integrally formed with the inlet-side land portion 22b. The catch mounting portion 22d has a smaller diameter than the inlet-side land portion 22b. The catch mounting portion 22d is disposed in the spring accommodating portion 31f.

[0045] [Electric Device] The electric device 23 shown in FIG. 3 strokes the spool 22. More specifically, the electric device 23 is attached to the housing 21 so as to close the opening on the other side of the spool bore 31 in the second direction, which in this embodiment is the opening of the insertion hole 31g. In this embodiment, the housing 21 is formed with a mounting hole 31h that surrounds the insertion hole 31g. The electric device 23 is attached to the housing 21 by inserting its tip into the mounting hole 31h. The electric device 23 is an electrically driven linear motion device that applies a load to the spool 22 according to the current-carrying state, thereby linearly moving the spool 22. The electric device 23 is, for example, a linear motion solenoid or a ball screw motor. In this embodiment, the electric device 23 is a linear motion solenoid. That is, the electric device 23 includes an electromagnetic solenoid 23a and a push rod 23b.

[0046] The electromagnetic solenoid 23a is attached to the housing 21, for example, by threading its tip into the mounting hole 31h. The electromagnetic solenoid 23a generates a load according to its energized state. The push rod 23b protrudes from the electromagnetic solenoid 23a toward the spool 22, with its tip abutting against the spool 22. The electromagnetic solenoid 23a applies a load according to its energized state to the spool 22 via the push rod 23b. In other words, the electromagnetic solenoid 23a pushes the spool 22 in one direction in the second direction via the push rod 23b with a load according to its energized state, causing the spool 22 to stroke.

[0047] The spring member 24 biases the spool 22 in the other second direction. That is, the spring member 24 biases the spool 22 against the load from the electric device 23. The spring member 24 is, for example, a compression coil spring. The spring member 24 is housed in the spring housing portion 31f. More specifically, the spring member 24 is mounted on the exterior of the seat mounting portion 22d. A spring seat 26 is inserted into the seat mounting portion 22d. The spring seat 26 abuts against one end surface of the inlet-side land portion 22b, and the spring member 24 is disposed in a compressed state between the spring seat 26 and the spring seat 25. As a result, the spool 22 is biased in the other second direction by the spring member 24.

[0048] [Operation of the Electric Pilot Valve] In the electric pilot valve 2, the spool 22 is biased by the spring member 24. Therefore, in a non-energized state where the electric device 23 is not energized, the spool 22 is located in the closed position (see FIGS. 1 and 5). Therefore, the communication between the inlet-side flow path 32 and the outlet-side flow path 33 is closed in the non-energized state. On the other hand, when the electric device 23 is energized, the electric device 23 pushes the spool 22 in one direction (the second direction) with a load corresponding to the energized state. This causes the spool 22 to stroke toward the open position. This causes the notch 22e to move from the communication hole 31a toward the inlet-side connection hole 31b, and eventually the tip of the notch 22e disengages from the communication hole 31a. This allows the inlet-side flow path 32 and the outlet-side flow path 33 to communicate with each other via the notch 22e. In the minute flow rate control region (hereinafter simply referred to as the "first flow rate control region") in which the inlet-side flow path 32 and the outlet-side flow path 33 communicate with each other via the notches 22e, the pilot fluid flows from the inlet-side flow path 32 into the inlet-side connecting hole 31b, and then passes through the inlet-side annular flow path 27 and each notch 22e to the communicating portion 28. The pilot fluid then flows out into the outlet-side flow path 33 through the outlet-side connecting hole 31c.

[0049] As the spool 22 further strokes in the second direction, the inlet land 22b eventually disengages from the communication hole 31a (see FIG. 4). The spool 22 then transitions from the first flow control region to the second flow control region, where the inlet land 22b and the communication hole 31a are open. In the second flow control region, pilot fluid flows from the inlet annular flow path 27 through the inlet annular flow path 27 to the communication portion 28. This causes a larger amount of pilot fluid to flow from the inlet flow path 32 to the outlet flow path 33.

[0050] In the electric pilot valve 2 configured in this manner, the inlet-side flow path 32 and the outlet-side flow path 33 are opened with an opening degree corresponding to the stroke amount of the spool 22, and a flow rate corresponding to the opening degree flows from the inlet-side flow path 32 to the outlet-side flow path 33. More specifically, in the first flow rate control region, the inlet-side flow path 32 and the outlet-side flow path 33 are connected to each other via the notch 22e. In the first flow rate control region, when the spool 22 strokes in one direction in the second direction, the notch 22e gradually opens from the tip side to the inlet-side connecting hole 31b with an opening degree corresponding to the stroke amount. Therefore, in the first flow rate control region, the flow rate of the pilot fluid is controlled to a minute flow rate corresponding to the opening degree of the notch 22e.

[0051] Furthermore, in the second flow rate control region, the inlet-side flow path 32 and the outlet-side flow path 33 are connected via the inlet-side land 22b and the communication hole 31a. The inlet-side land 22b is spaced apart from the communication hole 31a by an amount corresponding to the stroke amount of the spool 22. Therefore, the opening between the inlet-side land 22b and the communication hole 31a also corresponds to the stroke amount of the spool 22. Therefore, in the second flow rate control region, the flow rate of the pilot fluid is also controlled to a flow rate corresponding to the stroke amount.

[0052] The stroke amount of the spool 22 is controlled as follows. That is, the load from the electric device 23 (hereinafter simply referred to as the "load") and the biasing force from the spring member 24 (hereinafter simply referred to as the "biasing force") act on the spool 22 in a mutually opposing manner. On the other hand, the load applied to the spool 22 from the electric device 23 is smaller than the load applied to the spool in a conventional pilot-type spool valve. In addition to the load and biasing force, the spool 22 is also affected by a fluid force (hereinafter simply referred to as the "fluid force") applied by the pilot fluid flowing from the inlet-side flow path 32 to the outlet-side flow path 33. Therefore, the spool 22 strokes to a position where the load, biasing force, and fluid force are balanced, that is, by a stroke amount corresponding to the load, biasing force, and fluid force. Therefore, in the electric pilot valve 2, the influence of the fluid force is reduced as follows.

[0053] That is, in the electric pilot valve 2, the notch 22e is located on the other side of the inlet-side flow passage 32 in the second direction in the full-stroke state. Therefore, the pilot fluid can be prevented from flowing directly into the notch 22e after flowing from the inlet-side flow passage 32 into the inlet-side connecting hole 31b. That is, in the first flow rate control region, the pilot fluid flows from the inlet-side flow passage 32 through the inlet-side annular flow passage 27 into the notch 22e. Therefore, the pilot fluid flows into the notch 22e after being rectified in the inlet-side annular flow passage 27. This can suppress pressure fluctuations of the pilot fluid that occur in the notch 22e. This suppresses fluctuations in the fluid force acting on the spool 22. This can reduce the influence of the fluid force on the spool 22. Specifically, this can suppress the influence on the controllability of the stroke amount. Therefore, in the electric pilot valve 2, the accuracy of flow rate control in the energized state can be improved.

[0054] Furthermore, in the electric pilot valve 2, the inlet-side connecting hole 31b is formed with a smaller diameter than the outlet-side connecting hole 31c. Therefore, the flow path area of ​​the inlet-side annular flow path 27 is reduced like a throttle. This allows the pilot fluid to be more rectified. Therefore, fluctuations in the flow direction of the pilot fluid are suppressed. This reduces the influence of fluid force on the spool 22. More specifically, it is possible to suppress fluctuations in fluid force relative to the stroke amount. Therefore, in the electric pilot valve 2, the accuracy of flow rate control relative to the energized state can be improved.

[0055] Furthermore, in the electric pilot valve 2, one end of the outlet-side land portion 22c is positioned in the outlet-side connection hole portion 31c in the open position. More specifically, in this embodiment, one end of the outlet-side land portion 22c protrudes from the outlet-side slide hole portion 31e into the outlet-side opening 33a in the closed position. Therefore, the fluid force in the other second direction from the pilot fluid can be reliably received at one end of the outlet-side land portion 22c. Therefore, the fluid force in the one second direction acting on the spool 22 can be counteracted. This suppresses the effect of the fluid force on the spool 22. Specifically, the reaction force when stroking the spool 22 can be reduced, thereby suppressing malfunction of the spool 22.

[0056] Furthermore, in the electric pilot valve 2, the outlet-side land portion 22c has an inclined portion 22f on one end surface. The inclined portion 22f inclines toward the other second direction as it extends radially outward. This allows the pilot fluid guided to the outlet-side connecting hole 31c to be guided to the outlet-side flow path 33. This allows the flow of pilot fluid to be smoothly redirected toward the outlet-side flow path 33, allowing the pilot fluid to smoothly flow out to the outlet-side flow path 33. This reduces the fluid force in the other second direction that the pilot fluid exerts on one end of the outlet-side land portion 22c. This reduces the influence of the fluid force on the spool 22. Specifically, this reduces the reaction force when the spool 22 is stroked, thereby preventing malfunction of the spool 22. In particular, in the electric pilot valve 2, the inclined portion 22f is formed around the entire shaft portion 22a on one end surface of the outlet-side land portion 22c. This further reduces the influence of the fluid force on the spool 22.

[0057] [Operation of the Poppet Valve Device] The poppet valve device 1 includes the electric pilot valve 2 that operates as described above. When the electric pilot valve 2 is energized, it operates as follows. That is, in the electric pilot valve 2, the spool 22 strokes in one direction in the second direction, opening the gap between the inlet-side flow path 32 and the outlet-side flow path 33. This causes pilot fluid in the pilot chamber 11c of the poppet valve 4 to flow from the inlet-side flow path 32 to the outlet-side flow path 33 and then to be discharged to the secondary portion 12b of the flow path 12 via the connecting passage 3a (see the bold line in FIG. 3). Meanwhile, in the poppet valve 4, the pilot fluid is discharged from the pilot chamber 11c, opening the feedback flow path 14a that was closed by the check valve element 15. Then, working fluid is guided from the primary portion 12a of the flow path 12 to the pilot chamber 11c via the feedback flow path 14a and the annular passage portion 11d (see the bold line in FIG. 2). At this time, a pressure loss occurs in the annular passage 11d, and the pressure in the pilot chamber 11c, i.e., the pilot pressure, is reduced, and the main valve element 14 is lifted to a position where the pilot pressure, the primary side pressure of the flow passage 12, and the biasing force of the main valve spring member 16 are balanced.

[0058] The pilot pressure is a pressure that corresponds to the ratio of the flow path area of ​​the annular passage portion 11d to the opening between the inlet-side flow path 32 and the outlet-side flow path 33. Therefore, the main valve element 14 lifts by an amount that corresponds to the ratio of the flow path area of ​​the annular passage portion 11d to the opening between the inlet-side flow path 32 and the outlet-side flow path 33. Since the opening between the inlet-side flow path 32 and the outlet-side flow path 33 is controlled to an amount that corresponds to the energized state of the electric pilot valve 2, the main valve element 14 lifts by an amount that corresponds to the energized state of the electric pilot valve 2. Therefore, in the poppet valve device 1, the flow rate through the flow path 12 can be controlled, for example, according to the characteristics of the main valve element opening area relative to the lift amount.

[0059] In the electric pilot valve 2 of this embodiment, the notch 22e is formed at the other end of the inlet-side land portion 22b. The notch 22e is located on the other side of the inlet-side flow path 32 in the second direction in a full-stroke state. This prevents the pilot fluid from flowing directly into the notch 22e after flowing from the inlet-side flow path 32 into the inlet-side connecting hole 31b. Therefore, the pilot fluid flows into the notch 22e after being rectified in the inlet-side annular flow path 27. This suppresses pressure fluctuations of the pilot fluid at the notch 22e. This suppresses fluctuations in the fluid force acting on the spool 22. This reduces the effect of the fluid force on the spool 22.

[0060] Furthermore, in the electric pilot valve 2 of this embodiment, the notch 22e is located on the other side of the projected portion 22g in the second direction in the full-stroke state. This further prevents the flow that flows along the inlet-side flow passage 32 and enters the inlet-side connecting hole 31b from the inlet-side flow passage 32 from flowing directly into the notch 22e. This further reduces the effect of fluid force on the spool 22.

[0061] Furthermore, in the electric pilot valve 2 of this embodiment, the inlet-side connecting hole 31b is formed with a smaller diameter than the outlet-side connecting hole 31c. This reduces the flow path area of ​​the inlet-side annular flow path 27 like a throttle. This allows the pilot fluid to flow more smoothly. This further reduces the influence of fluid forces on the spool 22.

[0062] Furthermore, in the electric pilot valve 2 of this embodiment, one end of the outlet-side land portion 22c is located at the outlet-side connecting hole 31c in the open position. Therefore, the fluid force in the other second direction from the pilot fluid can be reliably received at one end of the outlet-side land portion 22c. This makes it possible to cancel out the fluid force in the one second direction acting on the spool 22. This makes it possible to suppress the effect of the fluid force on the spool 22.

[0063] Furthermore, in the electric pilot valve 2 of this embodiment, the outlet-side land portion 22c has an inclined portion 22f on one end surface. The inclined portion 22f inclines in the other second direction as it moves radially outward. This allows the pilot fluid guided to the outlet-side connecting hole 31c to be guided to the outlet-side flow path 33. This allows the flow of pilot fluid to be smoothly diverted toward the outlet-side flow path 33, allowing the pilot fluid to smoothly flow out to the outlet-side flow path 33. This reduces the fluid force in the other second direction that the pilot fluid exerts on one end of the outlet-side land portion 22c. This reduces the effect of the fluid force on the spool 22.

[0064] In the electric pilot valve 2 of this embodiment, the inclined portion 22f is formed around the entire periphery of the shaft portion 22a on one end surface of the outlet-side land portion 22c, thereby further suppressing the influence of fluid forces on the spool 22.

[0065] Furthermore, in the poppet valve device 1 of this embodiment, the spool strokes to transition the opening control to the first flow rate control region and the second flow rate control region, respectively, so that the motor-operated spool valve can control flow rates from very small to very large.

[0066] Furthermore, the poppet valve device 1 of this embodiment can be realized to have the above-described functions, thereby enabling the poppet valve device 1 to be controlled with higher accuracy.

[0067] <Other Embodiments> The electric pilot valve 2 of this embodiment is provided in the poppet valve device 1, but may be used alone. Furthermore, as in the electric pilot valve 2A of the poppet valve device 1A shown in FIG. 6 , the inlet-side flow path 32A and the outlet-side flow path 33A may extend radially outward in directions away from or toward each other. In this case, the projected portion 22Ag is, for example, as shown in FIG. 6 , a portion obtained by extending the inlet-side flow path 32A and projecting it onto the inlet-side land portion 22b (see the crosshatching in FIG. 6 ). That is, the projected portion 22Ag is a portion of the inlet-side flow path 32 that intersects with the inlet-side land portion 22b. The notch 22e is located on the other side of the projected portion 22Ag in the second direction. Note that both or at least one of the inlet-side flow path 32 and the outlet-side flow path 33 may extend in a direction perpendicular to the axis L1.

[0068] Furthermore, one end of the outlet-side land portion 22c does not necessarily have to be positioned in the outlet-side connection hole 31c, but may be positioned in the outlet-side slide hole 31e. The inlet-side connection hole 31b may have a larger diameter than the outlet-side connection hole 31c. Furthermore, the outlet-side land portion 22c does not necessarily have to have the inclined portion 22f around the entire periphery of the shaft portion 22a on one end surface, but may be formed only on the outer periphery of the one end surface. In this case, the inclined portion 22Af may be formed by, for example, R-chamfering as shown in FIG. 6 or C-chamfering. In this case, it is preferable that R and C are greater than or equal to 0.5.

[0069] Furthermore, in this embodiment, the spring member 24 is disposed on one side of the spool 22 in the second direction, but it may also be disposed on the other side of the spool 22 in the second direction.

[0070] An electric spool valve according to a first aspect includes a housing including a spool hole extending in an axial direction, an inlet-side flow passage connected to the spool hole, and an outlet-side flow passage connected to the spool hole; a spool that is slidably inserted into the spool hole and strokes to open and close the inlet-side flow passage and the outlet-side flow passage; and an electric device that strokes the spool, wherein the spool hole includes a communication hole portion and an inlet-side connection hole portion that is disposed on one axial side of the communication hole portion and is connected to the inlet-side flow passage. the inlet-side land portion has a notch, and an end portion on the other axial side is fitted into the communicating hole portion to close the gap between the inlet-side flow passage and the outlet-side flow passage; the inlet-side land portion has a notch, and an end portion on the other axial side is fitted into the communicating hole portion to close the gap between the inlet-side flow passage and the outlet-side flow passage; the notch is formed in the end portion on the other axial side of the inlet-side land portion, and is located on the other axial side of the inlet-side flow passage when the spool is fully stroked in the one axial direction.

[0071] According to the above aspect, the notch is formed at the end of the inlet-side land portion on the other axial side. The notch is located on the other axial side of the inlet-side flow passage when the spool is fully stroked in one axial direction. Therefore, the pilot fluid can be prevented from flowing directly into the notch after flowing from the inlet-side flow passage into the inlet-side connection hole. Therefore, the pilot fluid flows into the notch after being rectified around the spool. This can suppress pressure fluctuations of the pilot fluid in the notch. This can suppress fluctuations in fluid force acting on the spool. This can reduce the effect of fluid force on the spool.

[0072] In the electric spool valve of the second aspect, in the electric spool valve of the first aspect, the notch is located on the other axial side of a projected portion formed by extending the inlet-side flow path and projecting it onto the inlet-side land portion when the spool is at a full stroke in one axial direction.

[0073] According to the above aspect, the notch is located on the other axial side of the projected portion in the full-stroke state. This further prevents the flow that flows from the inlet-side flow passage into the inlet-side connecting hole along the inlet-side flow passage from flowing directly into the notch. This further reduces the effect of fluid force on the spool.

[0074] In a third aspect, in the electric spool valve of the first or second aspect, the spool hole further includes an outlet-side connecting hole portion that is arranged on the other axial side of the communicating hole portion and is connected to the outlet-side flow path, and the inlet-side connecting hole portion has a smaller diameter than the outlet-side connecting hole portion.

[0075] According to the above aspect, the inlet-side connecting hole is formed with a smaller diameter than the outlet-side connecting hole. Therefore, the flow path area of ​​the inlet-side annular flow path is reduced like a throttle. This allows the flow of pressure liquid flowing in from the inlet-side flow path to be more rectified. Therefore, the influence of fluid force on the spool can be further suppressed.

[0076] In a fourth aspect, in the electric spool valve of any one of the first to third aspects, the spool hole further includes an outlet-side connecting hole portion that is arranged on the other axial side of the communicating hole portion and is connected to the outlet-side flow path, and the spool further includes an outlet-side land portion that is arranged in the outlet-side connecting hole portion and has a larger diameter than the shaft portion, and the outlet-side land portion is arranged so that its end on the one axial side is positioned at the outlet-side connecting hole portion in the open position.

[0077] According to the above aspect, in the open position, one end of the outlet-side land portion is positioned in the outlet-side connection hole portion. Therefore, the one end of the outlet-side land portion can reliably receive the fluid force in the other axial direction from the pilot fluid. Therefore, the fluid force in the one axial direction acting on the spool can be canceled out. This suppresses the effect of the fluid force on the spool.

[0078] In the electric spool valve of a fifth aspect, in the electric spool valve of any one of the first to fourth aspects, the outlet-side land portion has an inclined portion on an end face on one axial side, and the inclined portion is formed on at least the outer peripheral edge portion of the end face on one axial side, and inclined toward the other axial side as it progresses radially outward.

[0079] According to the above aspect, the outlet-side land portion has an inclined portion on one end surface. The inclined portion inclines toward the other axial direction as it extends radially outward. Therefore, the pressure liquid guided to the outlet-side connection hole can be guided to the outlet-side flow path. This allows the flow of pressure liquid to be smoothly redirected toward the outlet-side flow path, allowing the pressure liquid to smoothly flow out to the outlet-side flow path. This reduces the fluid force in the other axial direction that the pressure liquid exerts on the one end of the outlet-side land portion. This reduces the effect of the fluid force on the spool.

[0080] In a sixth aspect of the motor-operated spool valve, in the motor-operated spool valve of the fifth aspect, the inclined portion is formed entirely around the shaft portion on one axial end face of the outlet land portion.

[0081] According to the above aspect, the inclined portion is formed around the entire shaft portion on the end face of the outlet land portion on the one side in the second direction, thereby further suppressing the effect of fluid force on the spool.

[0082] The electric spool valve in a seventh aspect is the electric spool valve of any one of the first to sixth aspects, wherein the spool strokes from a closed position that closes the inlet side flow path and the outlet side flow path, thereby transitioning opening control to a first flow control region in which the inlet side flow path and the outlet side flow path are connected via the notch, and a second flow control region in which the inlet side land portion is separated from the communication hole portion, thereby opening the communication hole portion.

[0083] According to the above aspect, the spool strokes to transition the opening control to the first flow rate control region and the second flow rate control region, respectively, thereby enabling the motor-operated spool valve to control flow rates from very small to very large.

[0084] A poppet valve device in an eighth aspect includes an electric spool valve of any one of the first to seventh aspects and a poppet valve that adjusts the opening of a flow path in accordance with a pilot pressure, and the electric spool valve adjusts the pilot pressure by stroking the spool.

[0085] According to the above aspect, it is possible to realize a poppet valve device having the above-described functions, thereby enabling the poppet valve device to be controlled with higher precision.

[0086] From the above description, many modifications and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present invention.

Claims

1. A housing including a spool hole extending in the axial direction, an inlet-side flow path connected to the spool hole, and an outlet-side flow path connected to the spool hole; a spool slidably inserted into the spool hole and stroked to open and close the space between the inlet-side flow path and the outlet-side flow path; and an electric device for stroking the spool, wherein the spool hole includes a communication hole and an inlet-side connection hole located on one axial side of the communication hole and connected to the inlet-side flow path, the spool includes a shaft inserted into the communication hole and having a smaller diameter than the communication hole, and an inlet-side land located in the inlet-side connection hole and having a larger diameter than the shaft but smaller than the inlet-side connection hole, the inlet-side land has a notch, and an end on the other axial side is fitted into the communication hole to close the space between the inlet-side flow path and the outlet-side flow path, the notch is formed at an end of the inlet-side land portion on the other axial side, and is located on the other axial side of the inlet-side flow path when the spool is fully stroked in the one axial direction.

2. An electric spool valve as described in claim 1, wherein the notch is located on the other axial side of the projection formed by extending the inlet side flow path and projecting it onto the inlet side land portion when the spool is fully stroked in one axial direction.

3. An electric spool valve as set forth in claim 1, wherein the spool hole further includes an outlet-side connecting hole portion that is located on the other axial side of the communicating hole portion and that is connected to the outlet-side flow path, and the inlet-side connecting hole portion has a smaller diameter than the outlet-side connecting hole portion.

4. An electric spool valve as described in claim 1, wherein the spool hole further includes an outlet-side connecting hole portion that is located on the other axial side of the communicating hole portion and is connected to the outlet-side flow path, the spool further includes an outlet-side land portion that is located in the outlet-side connecting hole portion and is formed with a larger diameter than the shaft portion, and the outlet-side land portion is positioned so that its end on the one axial side is positioned in the outlet-side connecting hole portion when in the open position.

5. An electric spool valve as set forth in claim 4, wherein the outlet-side land portion has an inclined portion on one axial end face, the inclined portion being formed on at least the outer peripheral edge of the one axial end face and inclining in the other axial direction as it extends radially outward.

6. The electric spool valve according to claim 5, wherein the inclined portion is formed on the end face of one axial side of the outlet-side land portion all around the shaft portion.

7. An electric spool valve as described in claim 1, wherein the spool, by stroking from a closed position in which the inlet side flow path and the outlet side flow path are closed, transitions opening control to a first flow control region in which the inlet side flow path and the outlet side flow path are connected via the notch, and to a second flow control region in which the inlet side land portion is separated from the communication hole portion to open the communication hole portion.

8. A poppet valve device comprising: the motorized spool valve according to claim 1; and a poppet valve that adjusts the opening of a flow path in accordance with pilot pressure, wherein the motorized spool valve adjusts the pilot pressure by stroking the spool.

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