Pressure reducing valve

Abstract

To prevent destruction of a pressure-reducing valve.SOLUTION: A pressure-reducing valve 100 comprises: a spool valve body 20; a first spring 34 that constantly energizes the spool valve body 20 in one axial direction; a second spring 44 that can energize the spool valve body 20 in the other axial direction; a first pressure chamber 32 that generates a first thrust for energizing the spool valve body 20 in one axial direction by pressure at a secondary pressure port 13 introduced therein; and a second pressure chamber 42 that generates a second thrust for energizing the spool valve body 20 in the other axial direction by pilot pressure introduced therein. As the second thrust decreases, the energizing force of the first spring 34 causes the spool valve body 20 to move in one direction, and when a position of the spool valve body 20 in the axial direction reaches a predetermined position, the energizing force of the second spring 44 for energizing the spool valve body 20 in the other direction acts on the spool valve body 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure reducing valve. [Background technology]

[0002] Patent Document 1 discloses a pressure reducing valve that includes a spool valve body that allows or blocks communication between an input port and an output port and allows or blocks communication between a drain port and an output port, and a spring that biases the spool valve body in one axial direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 5-2217 Summary of the Invention [Problem to be solved by the invention]

[0004] In a pressure reducing valve equipped with a spool valve body and a spring that biases the spool valve body, such as the pressure reducing valve described in Patent Document 1, when the operation of the pressure reducing valve is stopped, the pressure of the working fluid acting on the spool valve body decreases against the biasing force of the spring. When the pressure of the working fluid acting on the spool valve body decreases in this way, the biasing force of the spring causes the spool valve body to move, and the end of the spool valve body may collide with the housing or the like, which may damage the spool valve body or the housing that constitute the pressure reducing valve.

[0005] The present invention has been made in view of the above problems, and has an object to prevent damage to a pressure reducing valve. [Means for solving the problem]

[0006] The present invention is a pressure reducing valve that controls the communication state between a primary pressure passage and a secondary pressure passage and the communication state between a drain passage and a secondary pressure passage to reduce the pressure in the secondary pressure passage to a predetermined pressure, and includes a spool valve element that allows or blocks communication between the primary pressure passage and the secondary pressure passage and allows or blocks communication between the drain passage and the secondary pressure passage, a first biasing member that always biases the spool valve element in one direction in the axial direction, a second biasing member that can bias the spool valve element in the other direction in the axial direction, and a pressure in the secondary pressure passage that is guided to the spool valve element in the axial direction. and a second pressure chamber to which pilot pressure is introduced and which generates a second thrust that urges the spool valve element in the other axial direction. When the second thrust decreases, the spool valve element moves in one direction due to the urging force of the first urging member, and when the position of the spool valve element in the axial direction reaches a predetermined position, the urging force of the second urging member acts on the spool valve element, urging the spool valve element in the other direction.

[0007] In this invention, when the second thrust decreases, the spool valve element moves in one direction due to the biasing force of the first biasing member, but when the spool valve element reaches a predetermined axial position, the biasing force of the second biasing member acts on the spool valve element, biasing it in the other direction. In this way, the impact caused by the movement of the spool valve element is buffered by the second biasing member, so it is possible to prevent the spool valve element from colliding with the housing, cap, etc., which would damage the components that make up the pressure reducing valve.

[0008] The present invention also provides a pressure reducing valve that controls the communication state between a primary pressure passage and a secondary pressure passage and the communication state between a drain passage and the secondary pressure passage to reduce the pressure in the secondary pressure passage to a predetermined pressure, and is characterized in that it comprises a spool valve element that allows or blocks communication between the primary pressure passage and the secondary pressure passage and that allows or blocks communication between the drain passage and the secondary pressure passage, a first biasing member that constantly biases the spool valve element in one direction in the axial direction, a second biasing member that can bias the spool valve element in the other direction in the axial direction, and a pressure chamber into which pressure in the secondary pressure passage is directed and which generates a thrust that biases the spool valve element in the other direction in the axial direction, and wherein as the thrust decreases, the biasing force of the first biasing member moves the spool valve element in one direction, and when the position of the spool valve element in the axial direction reaches a predetermined position, the biasing force of the second biasing member that biases the spool valve element in the other direction acts on the spool valve element.

[0009] In this invention, when the thrust decreases, the spool valve element moves in one direction due to the biasing force of the first biasing member, but when the spool valve element reaches a predetermined axial position, the biasing force of the second biasing member acts on the spool valve element, biasing it in the other direction. In this way, the impact caused by the movement of the spool valve element is buffered by the second biasing member, so it is possible to prevent the spool valve element from colliding with the housing, cap, etc., which would damage the components that make up the pressure reducing valve.

[0010] The present invention is also characterized in that it further includes a biasing force adjustment section that adjusts the biasing force of the first biasing member acting on the spool valve body, and the second biasing member generates a biasing force that biases the spool valve body in one axial direction until the spool valve body moves in one direction and the position of the spool valve body in the axial direction reaches a predetermined position.

[0011] In this invention, the second biasing member generates a biasing force that counteracts the thrust generated in the second pressure chamber, similar to the first biasing member, until the spool valve element reaches a predetermined axial position. This makes it possible to use an elastic member with a relatively small spring constant as the first biasing member, and to reduce the size of the biasing force adjustment unit that adjusts the biasing force of the first biasing member.

[0012] The present invention is also characterized in that the second biasing member does not generate a biasing force to bias the spool valve body until the spool valve body moves in one direction and the position of the spool valve body in the axial direction reaches a predetermined position.

[0013] In this invention, the second biasing member does not generate a biasing force for biasing the spool valve element until the spool valve element reaches a predetermined axial position. In other words, the biasing force of the second biasing member does not act on the spool valve element during pressure adjustment. Because the second biasing member does not have any effect on the pressure adjustment of the pressure reducing valve, the pressure reducing valve can be used with the conventional settings. [Effects of the Invention]

[0014] According to the present invention, damage to the pressure reducing valve can be prevented. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing the configuration of a pressure reducing valve according to a first embodiment of the present invention. [Figure 2] 3A to 3C are diagrams for explaining the operation of the pressure reducing valve according to the first embodiment of the present invention. [Figure 3] 3A to 3C are diagrams for explaining the operation of the pressure reducing valve according to the first embodiment of the present invention. [Figure 4] FIG. 5 is a schematic view showing the configuration of a pressure reducing valve according to a second embodiment of the present invention. [Figure 5] FIG. 3 is a schematic view showing the configuration of a first modified example of a pressure reducing valve according to an embodiment of the present invention. [Figure 6]5A and 5B are diagrams for explaining the operation of a first modified example of a pressure reducing valve according to an embodiment of the present invention. [Figure 7] FIG. 4 is a schematic view showing the configuration of a second modified example of a pressure reducing valve according to an embodiment of the present invention. [Figure 8] 10A and 10B are diagrams for explaining the operation of a second modified example of a pressure reducing valve according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0017] First Embodiment First, a pressure reducing valve 100 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG.

[0018] The pressure reducing valve 100 is a device that reduces the pressure of working fluid supplied from a working fluid supply device such as a pump (not shown) to a predetermined pressure, and is used to supply working fluid at a constant pressure to a working fluid utilizing device such as a hydraulic actuator provided in a work machine, etc. In the following, an example will be described in which hydraulic oil is used as the working fluid, but other fluids such as hydraulic water may also be used as the working fluid.

[0019] As shown in FIG. 1, the pressure reducing valve 100 includes a spool valve element 20 having a plurality of land portions 21, 22 and an annular groove 23 formed between the land portions 21, 22, a housing 10 having an accommodation hole 18 for slidably accommodating the spool valve element 20, a first cap 30 attached to the housing 10 so as to close one open end of the accommodation hole 18, a second cap 40 attached to the housing 10 so as to close the other open end of the accommodation hole 18, a first spring 34 as a first biasing member housed in the first cap 30 and constantly biasing the spool valve element 20 in one axial direction (to the right in FIG. 1), a second spring 44 as a second biasing member housed in the second cap 40 and capable of biasing the spool valve element 20 in the other axial direction (to the left in FIG. 1), and a biasing force adjustment unit 35 for adjusting the biasing force of the first spring 34 acting on the spool valve element 20.

[0020] The housing 10 is formed with a primary pressure port 12 as a primary pressure passage, a secondary pressure port 13 as a secondary pressure passage, and a drain port 14 as a drain passage, each of which opens into the accommodation hole 18, and the primary pressure port 12 and the drain port 14 are arranged approximately symmetrically with the secondary pressure port 13 in between, as shown in Figure 1.

[0021] The primary pressure port 12 is connected to a pump (not shown) that discharges hydraulic oil, the secondary pressure port 13 is connected to a hydraulic fluid utilization device (not shown) that utilizes hydraulic oil that has been reduced in pressure to a certain level, and the drain port 14 is connected to a tank (not shown) that stores the hydraulic oil.

[0022] The spool valve element 20 has a first land portion 21 capable of closing the open end of the primary pressure port 12 that opens into the accommodation hole 18, a second land portion 22 capable of closing the open end of the drain port 14 that opens into the accommodation hole 18, and an annular groove 23 formed between the first land portion 21 and the second land portion 22 and capable of connecting the secondary pressure port 13 to either the primary pressure port 12 or the drain port 14. Note that Fig. 1 shows a so-called neutral state in which the primary pressure port 12 is closed by the first land portion 21, the drain port 14 is closed by the second land portion 22, and the secondary pressure port 13 is not connected to either the primary pressure port 12 or the drain port 14.

[0023] Of the two end faces of the first land portion 21, the end face 21a opposite the annular groove 23 faces the first pressure chamber 32 formed in the first cap 30, and of the two end faces of the second land portion 22, the end face 22a opposite the annular groove 23 faces the second pressure chamber 42 formed in the second cap 40.

[0024] Within the first pressure chamber 32, a first spring 34 is provided between the biasing force adjustment portion 35 and the first land portion 21 in a compressed state.

[0025] The biasing force adjustment unit 35 is mainly composed of a seat portion 35a that holds one end of the first spring 34, an adjustment bolt 35b that adjusts the position of the seat portion 35a in the axial direction, and a lock nut 35c that restricts the rotation of the adjustment bolt 35b, and the biasing force of the first spring 34 acting on the spool valve body 20 is adjusted by changing the position of the seat portion 35a in the axial direction.

[0026] In this way, the biasing force of the first spring 34 adjusted by the biasing force adjusting portion 35 is constantly acting on the spool valve element 20 in one axial direction via the first land portion 21.

[0027] Furthermore, the pressure of the secondary pressure port 13 is introduced into the first pressure chamber 32 through a secondary pressure introduction passage 33 .

[0028] The end surface 21a of the first land portion 21 facing the first pressure chamber 32 serves as a pressure-receiving surface on which the pressure of the secondary pressure port 13 introduced into the first pressure chamber 32 acts, and a first thrust corresponding to the pressure of the secondary pressure port 13 acts on the spool valve element 20 in one axial direction (to the right in FIG. 1). In other words, the first pressure chamber 32 serves as a pressure chamber into which the pressure of the secondary pressure port 13 is introduced to generate a first thrust that urges the spool valve element 20 in one axial direction.

[0029] Within the second pressure chamber 42, which faces the end face 22a of the second land portion 22, a second spring 44 is provided in a compressed state between an annular first seat portion 45 and a second seat portion 46. The spool valve body 20 is provided with a rod portion 24, which is axially extending from the end face 22a of the second land portion 22 and which is inserted into the first seat portion 45 and the second seat portion 46 that hold the second spring 44. A flange portion 25, which has an outer diameter larger than that of the rod portion 24, is provided at the tip of the rod portion 24.

[0030] The inner diameters of the first seat portion 45 and the second seat portion 46 are set to be larger than the outer diameter of the rod portion 24 and smaller than the outer diameter of the flange portion 25, and the outer diameters of the first seat portion 45 and the second seat portion 46 are set to be larger than the inner diameter of the accommodating hole 18.

[0031] The second cap 40, in which the second spring 44 is accommodated, is formed with a spring accommodating hole 40a having an inner diameter larger than the outer diameters of the first seat portion 45 and the second seat portion 46, a flange accommodating hole 40b formed coaxially with the spring accommodating hole 40a, with an inner diameter smaller than the outer diameter of the second seat portion 46 and larger than the outer diameter of the flange portion 25, and a step portion 40c connecting the spring accommodating hole 40a and the flange accommodating hole 40b.

[0032] Therefore, the position of the first seat portion 45 in the axial direction is determined by the first seat portion 45 abutting against either the side surface 10a of the housing 10 where the accommodating hole 18 opens or the end surface 22a of the second land portion 22, and the position of the second seat portion 46 in the axial direction is determined by the second seat portion 46 abutting against either the flange portion 25 or the step portion 40c.

[0033] Therefore, for example, as shown in Figure 1, when the first seat portion 45 abuts against the side surface 10a of the housing 10 and the second seat portion 46 abuts against the flange portion 25, the biasing force of the second spring 44 acts on the spool valve body 20 via the flange portion 25, and therefore, the biasing force of the second spring 44 acts on the spool valve body 20 in one axial direction (to the right in Figure 1), similar to the biasing force of the first spring 34.

[0034] 2, when the first seat portion 45 abuts against the side surface 10a of the housing 10 and the second seat portion 46 abuts against the step portion 40c of the second cap 40, the second spring 44 is compressed between the housing 10 and the second cap 40, and therefore the biasing force of the second spring 44 does not act on the spool valve element 20. The length of the rod portion 24 is set to be slightly longer than the distance between the side surface 10a of the housing 10 and the step portion 40c of the second cap 40.

[0035] As shown in FIG. 2, the second spring 44 may be held at approximately its natural length without being compressed when held between the first seat portion 45 that abuts against the housing 10 and the second seat portion 46 that abuts against the second cap 40.

[0036] Furthermore, for example, as shown in Figure 3, when the first seat portion 45 abuts against the end face 22a of the second land portion 22 and the second seat portion 46 abuts against the step portion 40c of the second cap 40, the biasing force of the second spring 44 acts on the spool valve body 20 via the second land portion 22, and therefore the biasing force of the second spring 44 acts on the spool valve body 20 in the opposite direction to the biasing force of the first spring 34, i.e., in the other axial direction (leftward in Figures 1 and 3).

[0037] In this way, the biasing force of the second spring 44 acts on the spool valve element 20 in one direction or the other in the axial direction.

[0038] Furthermore, a pilot pressure of a predetermined magnitude is introduced into the second pressure chamber 42 through a pilot pressure introduction passage 43 from a pilot pressure supply source (not shown).

[0039] The end face 22a of the second land portion 22 and the end face of the flange portion 25 that face the second pressure chamber 42 become pressure-receiving surfaces on which the pilot pressure introduced into the second pressure chamber 42 acts, and a second thrust corresponding to the pilot pressure acts on the spool valve element 20 in the other axial direction (leftward in FIG. 1), i.e., in a direction opposing the biasing force of the first spring 34. In other words, the second pressure chamber 42 becomes a pressure chamber into which the pilot pressure is introduced to generate a second thrust that biases the spool valve element 20 in the other axial direction.

[0040] The second land portion 22 is also provided with a notch 22b that allows the second pressure chamber 42 to communicate with the drain port 16. The notch 22b is a groove formed over a predetermined length along the axial direction on the outer peripheral surface of the second land portion 22, with one end opening at the end face 22a. The drain port 16 is a port that opens into the accommodation hole 18 on the side surface 10a side of the drain port 14, and like the drain port 14, communicates with a tank (not shown).

[0041] As shown in Figure 1, when the spool valve body 20 is in a neutral state, the second pressure chamber 42 and the drain port 16 are not in communication with each other through the notch 22b, and communication is blocked. However, when the spool valve body 20 moves in a direction that connects the secondary pressure port 13 with the primary pressure port 12, the second pressure chamber 42 and the drain port 16 are in communication with each other through the notch 22b.

[0042] In addition, the opening area of ​​the notch 22b that opens to the drain port 16, i.e., the flow path cross-sectional area of ​​the passage that connects the second pressure chamber 42 and the drain port 16, is set to gradually increase as the spool valve body 20 moves in the direction that connects the secondary pressure port 13 with the primary pressure port 12.

[0043] Next, the operation of the pressure reducing valve 100 having the above configuration will be described with reference to FIGS.

[0044] The pressure reducing valve 100 configured as described above is a so-called proportional pressure reducing valve that adjusts the pressure of the secondary pressure port 13 in accordance with the pilot pressure introduced into the second pressure chamber 42. In a state where a pilot pressure of a predetermined magnitude is not introduced into the second pressure chamber 42 from a pilot pressure supply source (not shown), i.e., in an inoperative state, only the biasing force of the first spring 34 acts on the spool valve element 20, and therefore, as shown in Figure 2 or Figure 3, the second land portion 22 of the spool valve element 20 is pressed against the first seat portion 45. The stopping position of the spool valve element 20 changes depending on the preset spring constants of the first spring 34 and second spring 44, etc.

[0045] When the pilot pressure is introduced into the second pressure chamber 42 through the pilot pressure introducing passage 43 and the pressure reducing valve 100 is activated, the spool valve element 20 moves from the position where the second land portion 22 contacts the first seat portion 45 as shown in FIG. 2 or 3 to a position where, for example, as shown in FIG. 1, a first resultant force obtained by combining the first thrust force urging the spool valve element 20 in one axial direction (to the right in FIG. 1) with the urging forces of the first spring 34 and the second spring 44 balances with a second thrust force urging the spool valve element 20 in the other axial direction (to the left in FIGS. 1 and 3).

[0046] For example, when the pressure in the secondary pressure port 13 increases, the first resultant force exceeds the second thrust, causing the spool valve body 20 to move to the right in Figure 1, connecting the secondary pressure port 13 to the drain port 14 and reducing the pressure in the secondary pressure port 13.

[0047] On the other hand, when the pressure in the secondary pressure port 13 decreases, the second thrust exceeds the first resultant force, causing the spool valve body 20 to move to the left in Figure 1, connecting the secondary pressure port 13 to the primary pressure port 12 and increasing the pressure in the secondary pressure port 13.

[0048] In this way, the pressure reducing valve 100 adjusts the pressure at the secondary pressure port 13 to a predetermined target pressure. The target pressure can be increased by using the biasing force adjustment unit 35 to reduce the biasing force of the first spring 34 or by increasing the pilot pressure, and can be decreased by using the biasing force adjustment unit 35 to increase the biasing force of the first spring 34 or by decreasing the pilot pressure.

[0049] Furthermore, if the pilot pressure is increased to raise the target pressure, the second thrust will suddenly increase, causing the spool valve body 20 to move significantly to the left in Figure 1, which could result in a temporary sudden rise in pressure at the secondary pressure port 13. However, as described above, when the spool valve body 20 moves in the direction that connects the secondary pressure port 13 to the primary pressure port 12, the second pressure chamber 42 to which the pilot pressure is directed will connect to the drain port 16 through the notch 22b.

[0050] Therefore, even if the pilot pressure is changed to increase the target pressure, the second pressure chamber 42 communicates with the drain port 16 through the notch 22b, and the hydraulic oil in the second pressure chamber 42 is discharged to the drain port 16, thereby preventing the pressure in the second pressure chamber 42 from increasing suddenly, i.e., preventing the second thrust from increasing suddenly. This makes it possible to avoid a temporary, sudden rise in the pressure at the secondary pressure port 13.

[0051] Pressure regulation by the pressure reducing valve 100 is stopped by stopping the supply of pilot pressure.

[0052] When the supply of pilot pressure is stopped, only the first resultant force acts on the spool valve element 20, causing the spool valve element 20 to move sharply toward the second pressure chamber 42 (to the right in Figure 1).

[0053] Here, in this embodiment, as described above, the second spring 44 arranged in the second pressure chamber 42 can urge the spool valve body 20 in the other axial direction (leftward in Figures 1 and 3).

[0054] Therefore, when pressure adjustment is completed, the spool valve body 20 moves sharply toward the second pressure chamber 42, and even if the end face 22a of the second land portion 22 abuts against the first seat portion 45 as shown in Figure 2, the impact caused by the movement of the spool valve body 20 is absorbed by the second spring 44 being compressed as shown in Figure 3.

[0055] In other words, when the supply of pilot pressure is stopped and the second thrust is reduced, the spool valve body 20 moves in one direction (to the right in Figures 1 and 3) toward the second pressure chamber 42, mainly due to the force of the first spring 34, and when the position of the spool valve body 20 in the axial direction reaches a predetermined position, i.e., the position where the end face 22a of the second land portion 22 abuts the first seat portion 45, the force of the second spring 44, which urges the spool valve body 20 in the other direction (to the left in Figures 1 and 3), acts on the spool valve body 20, and as a result, the impact accompanying the movement of the spool valve body 20 is buffered by the second spring 44.

[0056] In this way, by providing the second spring 44 that can bias the spool valve element 20 in the other axial direction, it is possible to prevent the spool valve element 20 from moving abruptly when pressure adjustment is completed, and from colliding with the housing, cap, etc., which would damage the components that make up the pressure reducing valve 100.

[0057] Furthermore, during pressure adjustment, i.e., while the position of the spool valve body 20 in the axial direction has not yet reached the above-mentioned predetermined position, the above-mentioned second spring 44 generates a spring force that counteracts the second thrust, similar to the first spring 34. This makes it possible to use a small spring with a relatively small spring constant as the first spring 34, and also makes it possible to miniaturize the spring force adjustment unit 35 that adjusts the spring force of the first spring 34.

[0058] According to the first embodiment described above, the following effects are achieved.

[0059] In the pressure reducing valve 100, when the supply of pilot pressure is stopped and the second thrust is reduced, the spool valve body 20 moves in one direction due to the biasing force of the first spring 34. However, when the position of the spool valve body 20 in the axial direction reaches a predetermined position, i.e., the position where the end face 22a of the second land portion 22 abuts the first seat portion 45, the biasing force of the second spring 44 acts on the spool valve body 20, biasing it in the other direction.

[0060] In this way, even if the biasing force of the first spring 34 is constantly acting on the spool valve element 20, the impact caused by the movement of the spool valve element 20 is buffered by the second spring 44. Therefore, when pressure adjustment is completed, the spool valve element 20 moves abruptly, and it is possible to prevent the spool valve element 20 from colliding with the housing, cap, etc., which would otherwise damage the components that make up the pressure reducing valve 100.

[0061] Second Embodiment Next, a pressure reducing valve 200 according to a second embodiment of the present invention will be described with reference to Fig. 4. The following description will focus on differences from the first embodiment, and the same components as those in the first embodiment will be denoted by the same reference numerals and will not be described again.

[0062] As shown in FIG. 4, the basic configuration of the pressure reducing valve 200, such as the housing 10, the spool valve body 20, the first cap 30, the first spring 34, the biasing force adjustment portion 35, the second cap 40, the second spring 44, and the retaining structure of the second spring 44, is the same as that of the pressure reducing valve 100 according to the first embodiment, but in the pressure reducing valve 200, the pressure of the secondary pressure port 13 is introduced through a secondary pressure introducing passage 33 to the second pressure chamber 42 as a pressure chamber, rather than to the first pressure chamber 32.

[0063] In the pressure reducing valve 200, the end face 22a of the second land portion 22 facing the second pressure chamber 42 and the end face of the flange portion 25 become pressure receiving surfaces on which the pressure of the secondary pressure port 13 led to the second pressure chamber 42 acts, and therefore a thrust force corresponding to the pressure of the secondary pressure port 13 acts on the spool valve body 20 in the other axial direction (leftward in Figure 4), i.e., in a direction counter to the biasing force of the first spring 34.

[0064] On the other hand, the first pressure chamber 32 is connected to a tank (not shown) through a drain passage (not shown). In other words, in the pressure reducing valve 200, only the second pressure chamber 42 functions as a pressure chamber that generates thrust to bias the spool valve element 20.

[0065] Furthermore, in the pressure reducing valve 200, the first land portion 21 closes the open end of the drain port 14 that opens into the accommodation hole 18, and the second land portion 22 closes the open end of the primary pressure port 12 that opens into the accommodation hole 18. In other words, the positions of the primary pressure port 12 and the drain port 14 of the pressure reducing valve 200 are interchanged with the positions of the primary pressure port 12 and the drain port 14 of the pressure reducing valve 100 according to the first embodiment described above, as shown in FIG.

[0066] As described above, the pressure reducing valve 100 according to the first embodiment is a so-called proportional pressure reducing valve that adjusts the pressure of the secondary pressure port 13 in accordance with the pilot pressure introduced into the second pressure chamber 42, whereas the pressure reducing valve 200 is a so-called fixed pressure reducing valve that adjusts the pressure of the secondary pressure port 13 in accordance with the pressure of the secondary pressure port 13 introduced into the second pressure chamber 42 without using pilot pressure.

[0067] Next, the operation of the pressure reducing valve 200 having the above configuration will be described with reference to FIG.

[0068] In the pressure reducing valve 200, the pressure at the secondary pressure port 13 has not yet risen and the pressure at the secondary pressure port 13 is not being introduced into the second pressure chamber 42 serving as a pressure chamber through the secondary pressure introduction passage 33, i.e., in an inoperative state, similar to the above-mentioned pressure reducing valve 100, only the biasing force of the first spring 34 acts on the spool valve body 20, so that the second land portion 22 of the spool valve body 20 is pressed against the first seat portion 45.

[0069] When the pressure of the secondary pressure port 13 is introduced into the second pressure chamber 42 through the secondary pressure introduction passage 33 and the pressure reducing valve 200 is activated, the spool valve body 20 moves from the position where the second land portion 22 contacts the first seat portion 45 to a position where, as shown in FIG. 4, a second resultant force, which is the sum of the biasing forces of the first spring 34 and the second spring 44 that bias the spool valve body 20 in one axial direction (to the right in FIG. 4), is balanced with a thrust that biases the spool valve body 20 in the other axial direction (to the left in FIG. 4).

[0070] For example, when the pressure in the secondary pressure port 13 increases, the thrust exceeds the second resultant force, causing the spool valve body 20 to move to the left in Figure 4, connecting the secondary pressure port 13 to the drain port 14 and reducing the pressure in the secondary pressure port 13.

[0071] On the other hand, when the pressure in the secondary pressure port 13 decreases, the second resultant force exceeds the thrust force, causing the spool valve body 20 to move to the right in Figure 4, connecting the secondary pressure port 13 to the primary pressure port 12 and increasing the pressure in the secondary pressure port 13.

[0072] In this way, the pressure reducing valve 200 adjusts the pressure at the secondary pressure port 13 to a predetermined target pressure. The target pressure can be increased by increasing the biasing force of the first spring 34 with the biasing force adjustment unit 35, and can be decreased by decreasing the biasing force of the first spring 34 with the biasing force adjustment unit 35.

[0073] Pressure regulation by the pressure reducing valve 200 is stopped by cutting off the supply of hydraulic oil to the primary pressure port 12 .

[0074] When the supply of hydraulic oil to the primary pressure port 12 is cut off, the pressure at the secondary pressure port 13 decreases, so that only the second resultant force acts on the spool valve body 20, causing the spool valve body 20 to move steeply toward the second pressure chamber 42 (to the right in Figure 4).

[0075] Here, in this embodiment, as in the first embodiment described above, the second spring 44 arranged in the second pressure chamber 42 can urge the spool valve body 20 in the other axial direction (to the left in Figure 4).

[0076] Therefore, even if the spool valve body 20 moves sharply toward the second pressure chamber 42 when pressure adjustment is completed and the end face 22a of the second land portion 22 abuts against the first seat portion 45, the impact caused by the movement of the spool valve body 20 is absorbed by the second spring 44 being compressed, as in the first embodiment described above.

[0077] In other words, as the pressure in the secondary pressure port 13 decreases and the thrust decreases, the spool valve body 20 moves in one direction (to the right in Figure 4) toward the second pressure chamber 42, mainly due to the force of the first spring 34.When the position of the spool valve body 20 in the axial direction reaches a predetermined position, i.e., the position where the end face 22a of the second land portion 22 abuts the first seat portion 45, the force of the second spring 44, which urges the spool valve body 20 in the other direction (to the left in Figure 4), acts on the spool valve body 20.As a result, the impact caused by the movement of the spool valve body 20 is buffered by the second spring 44.

[0078] In this way, by providing the second spring 44 that can bias the spool valve element 20 in the other axial direction, it is possible to prevent the spool valve element 20 from moving abruptly when pressure adjustment is completed, and from colliding with the housing, cap, etc., which would damage the components that make up the pressure reducing valve 200.

[0079] Furthermore, during pressure adjustment, i.e., while the position of the spool valve body 20 in the axial direction has not yet reached the above-mentioned predetermined position, the above-mentioned second spring 44 generates a spring force that counteracts the thrust, just like the first spring 34. This makes it possible to use a small spring with a relatively small spring constant as the first spring 34, and also makes it possible to miniaturize the spring force adjustment unit 35 that adjusts the spring force of the first spring 34.

[0080] According to the second embodiment described above, the following effects are achieved.

[0081] In the pressure reducing valve 200, when the pressure in the secondary pressure port 13 decreases and the thrust decreases, the spool valve body 20 moves in one direction due to the biasing force of the first spring 34. However, when the position of the spool valve body 20 in the axial direction reaches a predetermined position, i.e., the position where the end face 22a of the second land portion 22 abuts the first seat portion 45, the biasing force of the second spring 44 acts on the spool valve body 20, biasing the spool valve body 20 in the other direction.

[0082] In this way, even if the biasing force of the first spring 34 is constantly acting on the spool valve element 20, the impact caused by the movement of the spool valve element 20 is buffered by the second spring 44. Therefore, when pressure adjustment is completed, the spool valve element 20 moves abruptly, and it is possible to prevent the spool valve element 20 from colliding with the housing, cap, etc., which would otherwise damage the components that make up the pressure reducing valve 200.

[0083] Next, modified examples of the above-described embodiments will be described. Note that the following modified examples are also within the scope of the present invention, and it is possible to combine the configurations shown in the modified examples with the configurations described in the above-described embodiments, or to combine the configurations described in the following different modified examples.

[0084] In each of the above embodiments, the second spring 44 is arranged to cushion the impact caused by the movement of the spool valve element 20 when pressure adjustment is completed, and is also arranged to generate a biasing force that counteracts the thrust generated in the second pressure chamber 42 during pressure adjustment, similar to the first spring 34. Alternatively, the second spring 44 may be arranged only to cushion the impact caused by the movement of the spool valve element 220, 320 when pressure adjustment is completed, without generating a biasing force that counteracts the thrust generated in the second pressure chamber 42, as in a first modified example shown in Figures 5 and 6 and a second modified example shown in Figures 7 and 8.

[0085] 5 and 6, the second spring 44 is provided in a compressed state between the first seat portion 45 abutting against the side surface 10a of the housing 10 and the second seat portion 46 abutting against the step portion 40c of the second cap 40, as in the above-described embodiments, but the spool valve element 220 is not provided with the rod portion 24 or the flange portion 25. Note that, as shown in FIG. 5, the second spring 44 may be in a substantially natural length without being compressed when held between the first seat portion 45 abutting against the housing 10 and the second seat portion 46 abutting against the second cap 40.

[0086] Therefore, in the first variant, when pressure adjustment is completed, the spool valve body 220 moves sharply toward the second pressure chamber 42, and when the position of the spool valve body 220 in the axial direction reaches a predetermined position, i.e., the position where the end face 22a of the second land portion 22 abuts the first seat portion 45, the force of the second spring 44, which urges the spool valve body 220 in the other direction (leftward in Figure 6), acts on the spool valve body 220.

[0087] Therefore, in the first modified example, as in the above-described embodiments, the impact caused by the movement of the spool valve body 220 is buffered by the second spring 44, and therefore, damage to the components constituting the pressure reducing valve 300 due to the spool valve body 220 colliding with the housing, cap, etc. can be prevented.

[0088] Note that, in the first modified example, the second spring 44 does not generate any biasing force to bias the spool valve element 220 until the spool valve element 220 moves in one direction (to the right in FIGS. 5 and 6) when pressure adjustment is completed and the spool valve element 220 reaches a predetermined axial position, i.e., the position where the end face 22a of the second land portion 22 abuts against the first seat portion 45. In other words, the biasing force of the second spring 44 does not act on the spool valve element 220 during pressure adjustment.

[0089] In this way, the second spring 44 has no effect on the pressure regulation of the pressure reducing valve 300, and therefore the pressure reducing valve 300 can be used with the conventional settings.

[0090] 7 and 8, the spool valve element 320 is provided with a rod portion 24 and a flange portion 25, as in the above-described embodiments, and a second spring 44 is provided in a compressed state between a first seat portion 45 and a second seat portion 46 through which the rod portion 24 passes, but the outer diameters of the first seat portion 45 and the second seat portion 46 are set smaller than the inner diameter of the accommodating hole 18 and the outer diameter of the second land portion 22. Note that, as shown in FIG. 7, the second spring 44 may be in a substantially natural length without being compressed when held between the first seat portion 45 abutting against the end face 22a of the second land portion 22 and the second seat portion 46 abutting against the flange portion 25.

[0091] Therefore, in the second modified example, when pressure adjustment is completed, the spool valve body 320 moves sharply toward the second pressure chamber 42, and when the position of the spool valve body 320 in the axial direction reaches a predetermined position, i.e., the position where the second seat portion 46 abuts the step portion 40c of the second cap 40, the force of the second spring 44, which urges the spool valve body 320 in the other direction (leftward in Figure 8), acts on the spool valve body 320.

[0092] Therefore, in the second modified example, as in the above-described embodiments, the impact caused by the movement of the spool valve body 320 is buffered by the second spring 44, thereby preventing damage to the components constituting the pressure reducing valve 400 due to the spool valve body 320 colliding with the housing, cap, etc.

[0093] Note that, in the second modified example, the second spring 44 does not generate any biasing force to bias the spool valve element 320 until the spool valve element 320 moves in one direction (to the right in FIGS. 7 and 8) when pressure adjustment is completed and the spool valve element 320 reaches a predetermined axial position, i.e., the position where the second seat portion 46 abuts against the step portion 40c of the second cap 40. In other words, the biasing force of the second spring 44 does not act on the spool valve element 320 during pressure adjustment.

[0094] In this way, the second spring 44 has no effect on the pressure regulation of the pressure reducing valve 400, and therefore the pressure reducing valve 400 can be used with the conventional settings.

[0095] In the first and second modified examples described above, a coil spring such as the second spring 44 is used as the second biasing member, but since the second biasing member cushions the impact caused by the movement of the spool valve body 220, 320, an elastic member such as rubber may be used as the second biasing member instead of a coil spring.

[0096] Furthermore, in the first and second modified examples described above, similarly to the first embodiment, the pilot pressure is introduced to the second pressure chamber 42 through the pilot pressure introduction passage 43, but as in the second embodiment, the pressure of the secondary pressure port 13 may be introduced to the second pressure chamber 42 through the secondary pressure introduction passage 33. In other words, the first and second modified examples can be applied to either the first or second embodiment.

[0097] Furthermore, in each of the above embodiments, the second pressure chamber 42 that generates thrust is formed inside the second cap 40 that is attached to the housing 10 so as to close the open end of the accommodation hole 18. The location where the second pressure chamber 42 is formed is not limited to inside the second cap 40 that accommodates the second spring 44, and the second pressure chamber 42 may be formed anywhere as long as it can apply a thrust to the spool valve element 20 that counteracts the biasing force of the first spring 34.

[0098] Furthermore, in the first embodiment, the end face 21a of the first land portion 21 serves as a pressure-receiving surface on which the pressure of the secondary pressure port 13, which is led to the first pressure chamber 32, acts. Alternatively, in order to change the area of ​​the pressure-receiving surface, a cylindrical transmission member may be provided, one end of which faces the first pressure chamber 32 and the other end of which abuts against the end face 21a of the first land portion 21. For example, by making the outer diameter of the transmission member smaller than the outer diameter of the first land portion 21 and reducing the pressure-receiving surface on which the pressure of the secondary pressure port 13 acts, it is possible to reduce the first thrust described above.

[0099] The configuration, operation, and effects of the embodiment of the present invention will be described below.

[0100] The pressure reducing valve 100, 300, 400 includes a spool valve element 20, 220, 320 that allows or blocks communication between the primary pressure port 12 and the secondary pressure port 13 and allows or blocks communication between the drain port 14 and the secondary pressure port 13, a first spring 34 that constantly urges the spool valve element 20, 220, 320 in one direction in the axial direction, a second spring 44 that can urge the spool valve element 20, 220, 320 in the other direction in the axial direction, and a spring 44 that generates a first thrust to which the pressure of the secondary pressure port 13 is guided and that urges the spool valve element 20, 220, 320 in one direction in the axial direction. and a second pressure chamber 42 to which pilot pressure is introduced and which generates a second thrust that urges the spool valve element 20, 220, 320 in the other axial direction. As the second thrust decreases, the spool valve element 20, 220, 320 moves in one direction due to the urging force of the first spring 34, and when the position of the spool valve element 20, 220, 320 in the axial direction reaches a predetermined position, the urging force of the second spring 44 that urges the spool valve element 20, 220, 320 in the other direction acts on the spool valve element 20, 220, 320.

[0101] In this configuration, when the supply of pilot pressure is stopped and the second thrust decreases, the spool valve body 20, 220, 320 moves in one direction due to the force of the first spring 34, but when the position of the spool valve body 20, 220, 320 in the axial direction reaches a predetermined position, the force of the second spring 44 acts on the spool valve body 20, 220, 320, urging it in the other direction.

[0102] In this way, even if the biasing force of the first spring 34 is constantly acting on the spool valve element 20, 220, 320, the impact caused by the movement of the spool valve element 20, 220, 320 is buffered by the second spring 44. Therefore, when pressure adjustment is completed, the spool valve element 20, 220, 320 moves abruptly, and it is possible to prevent the spool valve element 20, 220, 320 from colliding with the housing, cap, etc., which would otherwise damage the components that make up the pressure reducing valve 100, 300, 400.

[0103] The pressure reducing valves 200, 300, 400 each include a spool valve element 20, 220, 320 that allows or blocks communication between the primary pressure port 12 and the secondary pressure port 13 and allows or blocks communication between the drain port 14 and the secondary pressure port 13, a first spring 34 that constantly urges the spool valve element 20, 220, 320 in one direction in the axial direction, a second spring 44 that can urge the spool valve element 20, 220, 320 in the other direction in the axial direction, and a pressure reducing valve 200, 300, 400 that is guided to the secondary pressure port 13 and that allows or blocks communication between the drain port 14 and the secondary pressure port 13. and a second pressure chamber 42 that generates a thrust that urges the spool valve element 20, 220, 320 in the other direction, and as the thrust decreases, the spool valve element 20, 220, 320 moves in one direction due to the urging force of the first spring 34, and when the position of the spool valve element 20, 220, 320 in the axial direction reaches a predetermined position, the urging force of the second spring 44 that urges the spool valve element 20, 220, 320 in the other direction acts on the spool valve element 20, 220, 320.

[0104] In this configuration, when the pressure in the secondary pressure port 13 decreases and the thrust decreases, the spool valve body 20, 220, 320 moves in one direction due to the force of the first spring 34, but when the position of the spool valve body 20, 220, 320 in the axial direction reaches a predetermined position, the force of the second spring 44 acts on the spool valve body 20, 220, 320, urging it in the other direction.

[0105] In this way, even if the biasing force of the first spring 34 is constantly acting on the spool valve element 20, 220, 320, the impact caused by the movement of the spool valve element 20, 220, 320 is buffered by the second spring 44. Therefore, when pressure adjustment is completed, the spool valve element 20, 220, 320 moves abruptly, and it is possible to prevent the spool valve element 20, 220, 320 from colliding with the housing, cap, etc., which would otherwise damage the components that make up the pressure reducing valve 200, 300, 400.

[0106] In addition, the pressure reducing valves 100, 200 further include a biasing force adjusting section 35 that adjusts the biasing force of the first spring 34 acting on the spool valve element 20, and the second spring 44 generates a biasing force that biases the spool valve element 20 in one axial direction until the spool valve element 20 moves in one direction and the position of the spool valve element 20 in the axial direction reaches a predetermined position.

[0107] In this configuration, the second spring 44 generates a biasing force that counteracts the thrust generated in the second pressure chamber 42, similar to the first spring 34, until the spool valve element 20 reaches a predetermined axial position. This makes it possible to use a small spring with a relatively small spring constant as the first spring 34, and also makes it possible to miniaturize the biasing force adjustment unit 35 that adjusts the biasing force of the first spring 34.

[0108] Furthermore, the second spring 44 of the pressure reducing valve 300, 400 does not generate a biasing force to bias the spool valve element 220, 320 until the spool valve element 220, 320 moves in one direction and reaches a predetermined position in the axial direction.

[0109] In this configuration, the second spring 44 does not generate a biasing force that biases the spool valve element 220, 320 until the spool valve element 220, 320 reaches a predetermined axial position. In other words, during pressure adjustment, the biasing force of the second spring 44 does not act on the spool valve element 220, 320. Because the second spring 44 does not have any effect on the pressure adjustment of the pressure reducing valve 300, 400, the pressure reducing valve 300, 400 can be used with the conventional settings.

[0110] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments. [Explanation of symbols]

[0111] 100, 200, 300, 400... Pressure reducing valve, 10... Housing, 12... Primary pressure port (primary pressure passage), 13... Secondary pressure port (secondary pressure passage), 14... Drain port (drain passage), 20, 220, 320... Spool valve body, 32... First pressure chamber, 34... First spring (first biasing member), 35... Biasing force adjustment portion, 42... Second pressure chamber (pressure chamber), 44... Second spring (second biasing member)

Claims

1. a pressure reducing valve that controls a communication state between a primary pressure passage and a secondary pressure passage and a communication state between a drain passage and the secondary pressure passage to reduce pressure in the secondary pressure passage to a predetermined pressure, a spool valve element that allows or blocks communication between the primary pressure passage and the secondary pressure passage and allows or blocks communication between the drain passage and the secondary pressure passage; a first biasing member that constantly biases the spool valve element in one direction in the axial direction; a second biasing member capable of biasing the spool valve element in the other axial direction; a first pressure chamber into which the pressure of the secondary pressure passage is introduced and which generates a first thrust that urges the spool valve element in the one axial direction; a second pressure chamber into which a pilot pressure is introduced and which generates a second thrust force that urges the spool valve element in the other axial direction, a pressure reducing valve, characterized in that, as the second thrust decreases, the spool valve element moves in the one direction due to the biasing force of the first biasing member, and when the position of the spool valve element in the axial direction reaches a predetermined position, the biasing force of the second biasing member that biases the spool valve element in the other direction acts on the spool valve element.

2. a pressure reducing valve that controls a communication state between a primary pressure passage and a secondary pressure passage and a communication state between a drain passage and the secondary pressure passage to reduce pressure in the secondary pressure passage to a predetermined pressure, a spool valve element that allows or blocks communication between the primary pressure passage and the secondary pressure passage and allows or blocks communication between the drain passage and the secondary pressure passage; a first biasing member that constantly biases the spool valve element in one direction in the axial direction; a second biasing member capable of biasing the spool valve element in the other axial direction; a pressure chamber into which the pressure of the secondary pressure passage is introduced to generate a thrust force that urges the spool valve element in the other axial direction, a pressure reducing valve, characterized in that, as the thrust decreases, the spool valve element moves in the one direction due to the biasing force of the first biasing member, and when the position of the spool valve element in the axial direction reaches a predetermined position, the biasing force of the second biasing member, which biases the spool valve element in the other direction, acts on the spool valve element.

3. 3. The pressure reducing valve according to claim 1 or 2, a biasing force adjusting section for adjusting the biasing force of the first biasing member acting on the spool valve body, a second biasing member that generates a biasing force that biases the spool valve element in the one axial direction until the spool valve element moves in the one axial direction and reaches the predetermined position in the axial direction.

4. 3. The pressure reducing valve according to claim 1 or 2, a second biasing member that does not generate a biasing force for biasing the spool valve element until the spool valve element moves in the one direction and the position of the spool valve element in the axial direction reaches the predetermined position.

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