Valve unit

Abstract

A valve unit (10) is provided with: a valve body (11) configured so as to be movable in the axial direction (Q) of a cylindrical inner wall surface (4) relative to the inner wall surface (4); and a seal ring (14) that is mounted in an annular mounting groove (16) provided in an outer peripheral part of the valve body (11) and that seals a gap between the inner wall surface (4) and the valve body (11). The seal ring (14) has a joint part (18), and the valve body (11) has an introduction part (20) that is capable of introducing a fluid and that communicates with the mounting groove (16). The introduction part (20) is positioned in a region on the side opposite to a region on the side where the joint part (18) is positioned, with reference to a second straight line (T2) that extends in a direction perpendicular to a first straight line (T1) passing through the center position (PR) of the seal ring (14) and the joint part (18) and that passes through the center position (PR), in a line of sight in the axial direction (Q).

Description

Valve Unit

[0001] The present invention relates to a valve unit.

[0002] Patent Document 1 describes a valve unit for a spool valve capable of switching a fluid flow path between a communication state and a cutoff state. This valve unit includes a valve body (referred to as a "spool" in Patent Document 1) and a seal ring (referred to as a "packing" in Patent Document 1).

[0003] The valve body is disposed in a valve chamber surrounded by a cylindrical inner wall surface (referred to as a "spool hole" in Patent Document 1), and is configured to be movable relative to the inner wall surface in the axial direction of the inner wall surface. The seal ring is mounted in an annular mounting groove (referred to as a "concave groove" in Patent Document 1) provided on the outer periphery of the valve body, and seals a gap between the inner wall surface and the valve body.

[0004] Japanese Unexamined Patent Publication No. 2020-20429

[0005] The valve unit described in Patent Document 1 is configured to be capable of switching the position of the valve body in the axial direction between a first position (referred to as a "first switching position" in Patent Document 1) and a second position different from the first position (referred to as a "second switching position" in Patent Document 1). When the valve body is located at the first position, a predetermined flow path through which fluid flows (the flow path connecting an air supply port and a second output port in Patent Document 1) is brought into a communication state. When the valve body is located at the second position, the flow path is blocked by the valve body and the seal ring, whereby the flow path is brought into a cutoff state.

[0006] Here, when the valve body moves from the first position toward the second position, fluid flows into a gap between the seal ring and a groove bottom portion that is the bottom of the mounting groove in which the seal ring is mounted (or due to fluid pressure acting thereon), misalignment of the seal ring (a deviation between the central axis position of the seal ring and the central axis position of the valve body) tends to occur.

[0007] This misalignment occurs only temporarily. When the fluid pressure between the seal ring and the groove bottom portion becomes uniform in the circumferential direction, the misalignment of the seal ring is eliminated.

[0008] In this case, if the seal ring has a joint, the temporary misalignment described above may cause the joint to be displaced outward. In that case, since the joint is prone to expansion, the pressure of the fluid from the inner side may cause the joint to protrude outward, which can lead to the seal ring coming off the valve body or becoming jammed between the valve chamber wall and the corner of the valve body.

[0009] If the seal ring gets jammed, problems such as spool valve overload, malfunction, and damage to the seal ring can occur.

[0010] The object of the present invention is to provide a valve unit that can prevent the seal ring from coming off the valve body and the seal ring from becoming jammed.

[0011] The features of the present invention are a valve unit in a spool valve capable of switching between a connected state and a blocked state for a fluid passage, comprising: a valve body disposed in a valve chamber surrounded by a cylindrical inner wall surface and configured to be movable in the axial direction of the inner wall surface relative to the inner wall surface; and a seal ring mounted in an annular mounting groove provided on the outer circumference of the valve body and sealing the space between the inner wall surface and the valve body, wherein the seal ring has a joint portion, and the valve body has an introduction portion that can introduce the fluid and communicates with the mounting groove, wherein the introduction portion is located in a region opposite to the region on the side where the joint portion is located, with reference to a second straight line passing through the center position of the seal ring and the joint portion, in line with respect to the axial direction.

[0012] In this configuration, when fluid is introduced between the seal ring and the bottom of the mounting groove, more fluid is introduced to the area where the introduction section is provided than to other areas. Furthermore, the introduction section is located in the region opposite to the region where the joint section is located, in terms of the axial line of sight.

[0013] This allows more fluid to be introduced between the seal ring and the bottom of the mounting groove in the region of the mounting groove opposite the joint of the seal ring. As a result, the direction of misalignment of the seal ring is such that the portion of the seal ring included in the region where the joint is located (the joint side portion) approaches the bottom of the mounting groove. Therefore, it is possible to avoid a situation where the joint expands due to the fluid pressure from the inner circumference and protrudes (overflows) to the outer circumference.

[0014] Therefore, this configuration makes it possible to realize a valve unit that can avoid situations in which the seal ring detaches from the valve body or becomes jammed.

[0015] Furthermore, in the present invention, it is preferable that the introduction portion is provided on the outer circumference of the valve body and is composed of a recess that is recessed radially inward.

[0016] This configuration allows for the installation of an inlet using a relatively simple structure. This makes it easier to reduce the manufacturing cost of the valve unit.

[0017] Furthermore, in the present invention, it is preferable that the recess depth of the recess is shallower than the depth of the mounting groove.

[0018] With this configuration, the recess depth of the recess becomes relatively shallow. This avoids a situation where the sealing performance near the recess becomes insufficient due to the recess being too deep.

[0019] Furthermore, in the present invention, it is preferable that the seal ring has an opposing side surface that faces the groove side surface, which is the side surface of the mounting groove, and that the opposing side surface is configured to abut against the portion of the groove side surface that is radially inward from the recess.

[0020] With this configuration, the opposing side surface contacts the portion of the groove side surface radially inward from the recess, making it easier to ensure sealing performance near the recess. This makes it possible to realize a valve unit that prevents the seal ring from coming off or getting stuck in the valve body due to fluid introduction through the recess, while still providing good sealing performance near the recess.

[0021] Furthermore, in the present invention, it is preferable that the introduction portion is provided at a location in the seal ring where the portion facing the joint portion is located, with respect to the center position.

[0022] In this configuration, fluid is introduced to the location where the opposing joint portions are situated. As a result, the direction of misalignment of the seal ring is such that the joint portion is displaced toward the bottom of the mounting groove (in other words, the joint portion is pulled toward the inner circumference). Therefore, it is possible to more reliably avoid a situation where the joint portion expands due to the fluid pressure from the inner circumference and protrudes toward the outer circumference. Consequently, it is possible to more reliably avoid situations where the seal ring comes off the valve body or becomes jammed.

[0023] Furthermore, in the present invention, the valve body preferably has a plurality of introduction portions, and the plurality of introduction portions are preferably arranged symmetrically with respect to the first straight line.

[0024] In this configuration, fluid is introduced at multiple points symmetrically around the first straight line. As a result, the direction of the resultant force of the back pressure acting on the seal ring is from the center of the seal ring toward the joint-facing portion (the part of the seal ring facing the joint). Consequently, the direction of misalignment of the seal ring is in the direction in which the joint is displaced toward the bottom of the mounting groove (in other words, the direction in which the joint is pulled toward the inner circumference). Therefore, the situation in which the joint expands due to the fluid pressure from the inner circumference and protrudes toward the outer circumference can be more reliably avoided. Thus, the situation in which the seal ring comes off the valve body and the situation in which the seal ring gets caught can be more reliably avoided.

[0025] Furthermore, in the present invention, it is preferable to include a rotation restricting portion that restricts the circumferential rotation of the seal ring relative to the valve body.

[0026] This configuration prevents the seal ring from rotating circumferentially relative to the valve body due to external forces (such as friction), which can alter the positional relationship between the inlet and the joint. This avoids a situation where the direction of misalignment of the seal ring changes due to a change in the positional relationship between the inlet and the joint.

[0027] This is a cross-sectional view showing the spool valve. This is a cross-sectional view showing the spool valve. This is a cross-sectional view showing the large diameter portion and seal ring, etc. This is a diagram showing the large diameter portion and seal ring, etc. from the line of sight in the axial direction. This is a diagram showing the large diameter portion and seal ring, etc. from the line of sight from the radially outside. This is a cross-sectional view taken along the line VI-VI in Figures 5 and 11. This is a diagram showing the misalignment of the seal ring from the line of sight in the axial direction. This is a cross-sectional view showing the large diameter portion and seal ring, etc. This is a diagram showing the large diameter portion and seal ring, etc. from the line of sight in the axial direction of another embodiment (1). This is a cross-sectional view showing the large diameter portion and seal ring, etc. of another embodiment (2). This is a diagram showing the large diameter portion and seal ring, etc. from the line of sight from the radially outside of another embodiment (2). This is a cross-sectional view showing the large diameter portion and seal ring, etc. of another embodiment (3). This is a diagram showing the large diameter portion and seal ring, etc. from the line of sight in the axial direction of another embodiment (3). This is a cross-sectional view showing the large diameter portion and seal ring, etc. of another embodiment (4). This is a diagram showing the large diameter portion and seal ring from the line of sight from the radially outside of another embodiment (4). This is a diagram showing the seal ring from the line of sight in the axial direction of another embodiment (5). This is a diagram showing the joint portion of the step structure from the line of sight in the axial direction. This figure shows the joint of a step structure as viewed from the radially outside. This figure shows the joint of a straight structure as viewed from the axial direction. This figure shows the joint of a straight structure as viewed from the radially outside. This figure shows the joint of an angle structure as viewed from the axial direction. This figure shows the joint of an angle structure as viewed from the radially outside.

[0028] Embodiments for carrying out the present invention will be described with reference to the drawings.

[0029] [Spool Valve] Figures 1 and 2 show a spool valve 1. The spool valve 1 comprises a housing 2. The housing 2 has an inner wall surface 4. Figures 1 and 2 show a first central axis P1, which is the central axis of the inner wall surface 4. The inner wall surface 4 is formed in a cylindrical shape centered on the first central axis P1.

[0030] Figures 1 and 2 show the axial direction Q of the inner wall surface 4. The axial direction Q is the direction in which the first central axis P1 extends.

[0031] A valve chamber 5 is formed inside the housing 2. The valve chamber 5 is a space enclosed by the inner wall surface 4. The valve chamber 5 has a valve chamber body 6 and an enlarged diameter portion 7. The enlarged diameter portion 7 is a portion with a larger diameter than the valve chamber body 6.

[0032] As shown in Figure 1, the housing 2 has an input passage 8 and an output passage 9. The input passage 8 communicates with an enlarged diameter section 7. The output passage 9 communicates with another enlarged diameter section 7. These two enlarged diameter sections 7 are connected via the valve chamber body section 6.

[0033] The input passage 8 and the output passage 9 are both passages through which a fluid (for example, a gas such as air, or a liquid such as water or oil) flows. The spool valve 1 is configured to receive fluid from the input passage 8 into the valve chamber 5. The spool valve 1 is also configured to discharge the fluid in the valve chamber 5 through the output passage 9.

[0034] As shown in Figures 1 and 2, the spool valve 1 includes a valve unit 10. The valve unit 10 is located in the valve chamber 5. The valve unit 10 is configured to be movable along the axial direction Q relative to the inner wall surface 4. Although not particularly limited, the valve unit 10 may be configured to be driven along the axial direction Q by a motor or an electromagnetic solenoid.

[0035] Figures 1 and 2 show the first position S1 and the second position S2. The valve unit 10 is configured to be movable between the first position S1 and the second position S2.

[0036] As shown in Figure 1, when the valve unit 10 is in the first position S1, the fluid received from the input passage 8 through the enlarged diameter section 7 into the valve chamber body 6 passes through another enlarged diameter section 7 to reach the output passage 9 and is discharged from the output passage 9. In other words, in this case, the flow path connecting the input passage 8 and the output passage 9 is in communication.

[0037] In contrast, as shown in Figure 2, when the valve unit 10 is in the second position S2, the flow path connecting the input passage 8 and the output passage 9 is blocked by the valve unit 10. That is, in this case, the flow path connecting the input passage 8 and the output passage 9 is blocked. In this case, fluid does not flow from the input passage 8 to the output passage 9.

[0038] Thus, the spool valve 1 is configured to allow switching between a connected state and a blocked state for the fluid flow path.

[0039] [Valve body and seal ring] As shown in Figures 1 and 2, the valve unit 10 includes a valve body 11. The valve body 11 has a large-diameter portion 12 and a small-diameter portion 13. Both the large-diameter portion 12 and the small-diameter portion 13 have a cylindrical outer shape extending in the axial direction Q. The large-diameter portion 12 is larger in diameter than the small-diameter portion 13.

[0040] The material of the valve body 11 may be, for example, metal or resin. In particular, by using resin as the material, weight reduction can be achieved. Specific examples of resins include polyamide (PA), fluororesins (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), etc.) and mixtures thereof, as well as super engineering plastics such as liquid crystal polymer (LCP), polyimide (PI), polyetherketone (PEK), polyaryletherketone (PAEK), polyetherketoneetherketoneketone (PEKEKK), polyetheretherketone (PEEK), and polyphenylene sulfide (PPS).

[0041] Furthermore, the material of the housing 2 may also be metal, resin, or the like, similar to the valve body 11.

[0042] As shown in FIGS. 1 to 3, the valve unit 10 includes a seal ring 14. As shown in FIG. 4, the seal ring 14 is an annular (ring-shaped) member and is attached to the large diameter portion 12. In FIG. 4, the symbol denoted by reference sign "Q" indicates that the direction perpendicular to the drawing sheet is the axial direction Q.

[0043] The large diameter portion 12 and the seal ring 14 will be described in detail. As shown in FIGS. 3 and 4, a mounting groove 16 is provided on the outer peripheral portion of the large diameter portion 12. The mounting groove 16 is a groove having a shape recessed from the outer peripheral surface of the large diameter portion 12 toward the inner peripheral side. The mounting groove 16 is formed in an annular (ring-shaped) shape centered on a second central axis P2 (see FIGS. 1, 2 and 4). The second central axis P2 is the central axis of the valve body 11 (particularly, the large diameter portion 12). The seal ring 14 is mounted in the mounting groove 16.

[0044] As shown in FIGS. 2 and 4, the seal ring 14 is configured to seal between a portion of the inner wall surface 4 that defines the valve chamber main body 6 (in other words, a portion corresponding to the valve chamber main body 6) and the valve body 11 (particularly, the large diameter portion 12). That is, the valve unit 10 includes the seal ring 14 that is mounted in the annular mounting groove 16 provided on the outer peripheral portion of the valve body 11 and seals between the inner wall surface 4 and the valve body 11.

[0045] As described above, the valve body 11 and the seal ring 14 are part of the valve unit 10. Therefore, when the valve unit 10 moves along the axial direction Q as described above, the valve body 11 and the seal ring 14 also move along the axial direction Q in the same manner. That is, the valve unit 10 includes the valve body 11 that is disposed in the valve chamber 5 surrounded by the cylindrical inner wall surface 4 and is configured to be movable relative to the inner wall surface 4 in the axial direction Q of the inner wall surface 4.

[0046] As shown in FIG. 4, the seal ring 14 has an abutment 18. Although not particularly limited, the structure of the abutment 18 may be a known structure such as a straight structure (right-angle abutment), an angle structure (oblique abutment), or a step structure (stepped abutment).

[0047] Further, the seal ring 14 has a butt opposing portion 19. The butt opposing portion 19 is a portion of the seal ring 14 that faces the butt portion 18 with reference to the center position PR. More specifically, FIG. 7 shows a butt shape range 18a which is a range where the butt shape of the butt portion 18 is formed. In the seal ring 14, the range of the position opposite to the butt shape range 18a with respect to the center position PR is the butt opposing portion 19.

[0048] The material of the seal ring 14 may be, for example, a resin that is a material having slidability and wear resistance. Specific examples of the resin include polyamide (PA), fluororesin (polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), etc.), mixtures thereof, liquid crystal polymer (LCP), polyimide (PI), polyether ketone (PEK), polyaryl ether ketone (PAEK), polyether ketone ether ketone ketone (PEKEKK), polyether ether ketone (PEEK), super engineering plastics represented by polyphenylene sulfide (PPS), etc. In addition, the material of the seal ring 14 may be a material other than resin as long as it has an elastic modulus of 1 GPa (gigapascal) or more.

[0049] As shown in FIG. 3, tapered surfaces 17 are respectively formed at both ends in the axial direction Q at the outer peripheral end of the seal ring 14. These tapered surfaces 17 are inclined such that the mutual distance in the axial direction Q becomes narrower toward the outer peripheral side. Thereby, the seal ring 14 has a shape that narrows toward the outer peripheral side.

[0050] When the housing 2 is made of resin, the housing 2 may deform due to changes in the usage environment such as temperature, resulting in uneven clearance between the inner wall surface 4 and the valve body 11 (especially the large-diameter portion 12). Even in such a case, the guide action provided by the tapered surfaces 17 can prevent the seal ring 14 from being caught.

[0051] [Introduction Section] As shown in Figures 3 to 5, the large-diameter section 12 has an introduction section 20. The introduction section 20 is provided on the upstream side in the direction of fluid flow relative to the mounting groove 16 (seal ring 14). The introduction section 20 is capable of introducing fluid and is in communication with the mounting groove 16. As a result, the fluid introduced from the upstream side by the introduction section 20 flows into the mounting groove 16.

[0052] Thus, the valve body 11 has an introduction portion 20 that can introduce fluid and communicates with the mounting groove 16.

[0053] Here, Figure 4 shows a first straight line T1 and a second straight line T2. The first straight line T1 is a straight line that passes through the center position PR of the seal ring 14 and the joint portion 18 in the line of sight in the axial direction Q. The second straight line T2 is a straight line that extends perpendicularly to the first straight line T1 and passes through the center position PR in the line of sight in the axial direction Q. In the state shown in Figure 4, the center position PR of the seal ring 14 coincides with the positions of the first central axis P1 and the second central axis P2 in the line of sight in the axial direction Q.

[0054] Here, the first straight line T1 will be described in detail. As shown in Figures 17 and 18, the joint portion 18 in this embodiment has a step structure (stepped joint). The joint portion 18 has a first free end 51 and a second free end 52. Both the first free end 51 and the second free end 52 are the free ends of the seal ring 14. The first free end 51 extends in a first direction C1 in the circumferential direction. The second free end 52 extends in a second direction C2 in the circumferential direction. The second direction C2 is the opposite direction to the first direction C1.

[0055] Figure 17 shows the first extension end 53, which is the extension end of the first free end 51, the second extension end 54, which is the extension end of the second free end 52, and the central position CE. The central position CE is the midpoint between the first extension end 53 and the second extension end 54 in the circumferential direction. As shown in Figure 17, the first straight line T1 passes through the joint portion 18, in particular the central position CE, in line with respect to the axial direction Q.

[0056] Furthermore, the above explanation regarding the first straight line T1 applies equally to any structure of the joint portion 18, for example, to a straight structure (see Figures 19 and 20) and an angle structure (see Figures 21 and 22).

[0057] Furthermore, Figure 4 shows the first region R1 and the second region R2. The first region R1 is the region on the side where the joint opposing portion 19 is located, with respect to the second straight line T2. The second region R2 is the region on the side where the joint portion 18 is located, with respect to the second straight line T2. In other words, the first region R1 is the region opposite to the region on the side where the joint portion 18 is located (in other words, the second region R2), with respect to the second straight line T2.

[0058] Furthermore, the introduction portion 20 is located in the first region R1 in the line of sight in the axial direction Q. That is, in the line of sight in the axial direction Q, the introduction portion 20 extends perpendicularly to the first straight line T1 that passes through the center position PR of the seal ring 14 and the joint portion 18 (particularly the central position CE), and is located in the region opposite to the region on the side where the joint portion 18 is located, with reference to the second straight line T2 that passes through the center position PR.

[0059] In this embodiment, the introduction portion 20 is provided in the first region R1, particularly in the location where the joint-facing portion 19 is located. That is, the introduction portion 20 is provided in the location where the joint-facing portion 19, which is the part of the seal ring 14 that faces the joint portion 18 with respect to the center position PR, is located.

[0060] Furthermore, when the position of the joint portion 18 (particularly at the central position CE) is 0° and the position of the joint opposing portion 19 is 180° in the line of sight along the axial direction Q, the first region R1 is in the range of 90° to 270°. In this case, the introduction portion 20 is provided within the range of 90° to 270° (particularly at the 180° position).

[0061] [Recess] As shown in Figures 3 to 5, the introduction portion 20 in this embodiment is composed of a recess 21. The recess 21 is provided on the outer circumference of the large diameter portion 12 and is recessed radially inward. That is, the introduction portion 20 is composed of a recess 21 provided on the outer circumference of the valve body 11 and recessed radially inward.

[0062] Here, Figure 3 shows the first length L1 and the second length L2. The first length L1 is the recess depth of the recess 21. The second length L2 is the depth of the mounting groove 16. The first length L1 is shorter than the second length L2. That is, the recess depth of the recess 21 is shallower than the depth of the mounting groove 16. Note that the recess depth is the depth in the recessing direction. As described above, the recess 21 is recessed radially inward. That is, the recessing direction of the recess 21 is radially inward, and the recess depth of the recess 21 is the depth in radially inward.

[0063] The first length L1 is preferably 10 to 70% (particularly 10 to 60%, more preferably 10 to 50%) of the second length L2. This allows fluid to flow into the mounting groove 16 via the recess 21 while ensuring a seal between the mounting groove 16 and the seal ring 14 when the first opposing side surface 31 (described later) is in contact with the first groove side surface 61 (described later).

[0064] As shown in Figure 3, the mounting groove 16 has a groove bottom 60, a first groove side surface 61 (corresponding to the "groove side surface" according to the present invention), and a second groove side surface 62. The groove bottom 60 is the bottom of the mounting groove 16. The first groove side surface 61 is the side surface of the mounting groove 16 located on one side in the axial direction Q. The second groove side surface 62 is the side surface of the mounting groove 16 located on the other side in the axial direction Q.

[0065] Furthermore, the large-diameter portion 12 has a first end face 23 and a second end face 24. The first end face 23 is one end face of the large-diameter portion 12 in the axial direction Q. The second end face 24 is the other end face of the large-diameter portion 12 in the axial direction Q.

[0066] As shown in Figure 3, the recess 21 is formed in the axial direction Q from the first groove side surface 61 to the end face of the valve body 11 facing the fluid upstream side (specifically, the first end face 23). Because the recess 21 extends to the first end face 23, it facilitates the introduction of fluid into the recess 21. Therefore, fluid can easily flow into the portion of the mounting groove 16 that communicates with the recess 21.

[0067] As shown in Figure 5, the recess 21 is formed in a rectangular shape (approximately rectangular) when viewed from the radially outer side toward the center. However, the present invention is not limited thereto. For example, the recess 21 may be formed in a semicircular shape, a fan shape, a trapezoid shape, etc., when viewed from the radial side. The shape of the recess 21 may be any shape as long as it allows fluid to flow easily into the portion of the mounting groove 16 that the recess 21 communicates with.

[0068] [Misalignment] When the valve unit 10 is in the second position S2 (see Figure 2), the seal ring 14 abuts against the portion of the inner wall surface 4 between the input passage 8 and the output passage 9. As a result, the flow path connecting the input passage 8 and the output passage 9 is blocked.

[0069] Then, as the valve unit 10 moves from the second position S2 to the first position S1, when the seal ring 14 reaches the enlarged diameter portion 7, the seal ring 14 is separated from the inner wall surface 4. Consequently, the flow path connecting the input passage 8 and the output passage 9 becomes connected.

[0070] Furthermore, as the valve unit 10 moves further toward the first position S1, the seal ring 14 passes through the enlarged diameter portion 7 and, as shown in Figure 1, comes into contact with the portion of the inner wall surface 4 that is opposite to the enlarged diameter portion 7 and away from the input passage 8. However, this does not block the flow path connecting the input passage 8 and the output passage 9.

[0071] Furthermore, as the valve unit 10 moves from the first position S1 to the second position S2, the large-diameter portion 12 and the seal ring 14 pass through the enlarged diameter portion 7 and enter the valve chamber body portion 6. As a result, the seal ring 14 comes into contact with the portion of the inner wall surface 4 between the input passage 8 and the output passage 9. Consequently, the flow path connecting the input passage 8 and the output passage 9 is blocked.

[0072] Here, as the valve unit 10 moves from the first position S1 to the second position S2, the large-diameter portion 12 and the seal ring 14 pass through the enlarged diameter portion 7 and then enter the valve chamber body portion 6. As the valve unit 10 (seal ring 14) moves, the cross-sectional area of ​​the flow path connecting the input passage 8 and the output passage 9 decreases. As a result, a relatively large back pressure is applied to the large-diameter portion 12 and the seal ring 14. Back pressure is the force that pushes the seal ring 14 from the inner circumference to the outer circumference.

[0073] Here, Figure 6 shows the large-diameter portion 12 and the inner wall surface 4 immediately after the large-diameter portion 12 enters the valve chamber body portion 6, after the large-diameter portion 12 and the seal ring 14 have passed the enlarged-diameter portion 7, as the valve unit 10 is moving from the first position S1 to the second position S2. This figure is a cross-sectional view taken along the line VI-VI in Figure 5, and is a view of the cross-section at the upstream end of the recess 21 (hereinafter referred to as the "comparative cross-section") as seen from the upstream side in the axial direction Q. In Figure 6, the seal ring 14 is not shown. Also in Figure 6, the first gap 27 and the second gap 28 in the comparative cross-section are shown. The first gap 27 is the portion located in the first region R1 of the gap between the large-diameter portion 12 and the inner wall surface 4 in the line of sight in the axial direction Q. The second gap 28 is the portion located in the second region R2 of the gap between the large-diameter portion 12 and the inner wall surface 4 in the line of sight in the axial direction Q. In the example shown in Figure 5, there is only one recess 21. However, if multiple recesses 21 are provided, the positions of the upstream ends of each recess 21 are compared to identify the recess 21 located furthest upstream. The cross-section at the upstream end of the identified recess 21 becomes the comparison cross-section.

[0074] As described above, the first region R1 is provided with an introduction section 20 (recess 21). Therefore, as shown in Figure 6, when the position of the first central axis P1 and the position of the second central axis P2 coincide in the line of sight in the axial direction Q, and the large diameter section 12 is located in the valve chamber body 6, the area of ​​the first gap 27 in the comparison cross-section is larger than the area of ​​the second gap 28 by the area of ​​the introduction section 20. As a result, when a relatively large back pressure is applied to the large diameter section 12 and the seal ring 14 as described above, more fluid flows into the first gap 27 (especially the portion of the introduction section 20) than into the second gap 28.

[0075] As a result, the back pressure acting between the inner circumferential surface of the seal ring 14 and the groove bottom 60 due to the inflow of fluid is greater in the first region R1 than in the second region R2. Consequently, as shown in Figure 7, the seal ring 14 is displaced radially relative to the large diameter portion 12. At this time, the center position PR of the seal ring 14 is shifted from the position of the second central axis P2 in the line of sight along the axial direction Q. In other words, misalignment of the seal ring 14 occurs.

[0076] Then, as shown in Figure 7, the direction of the misalignment at this time is in the direction in which the opposing joint portion 19 moves away from the groove bottom portion 60 (in other words, the direction in which the joint portion 18 moves closer to the groove bottom portion 60).

[0077] Note that the misalignment shown in Figure 7 is a temporary phenomenon. After the misalignment occurs, the fluid pressure between the inner circumferential surface of the seal ring 14 and the groove bottom 60 approaches a uniform state in the circumferential direction. Consequently, the center position PR of the seal ring 14 approaches the positions of the first central axis P1 and the second central axis P2. As a result, the misalignment is eventually resolved naturally.

[0078] [Contact between opposing side surface and groove side surface] As shown in Figures 3 and 8, the seal ring 14 has a first opposing side surface 31 (corresponding to the "opposing side surface" according to the present invention) and a second opposing side surface 32. The first opposing side surface 31 is the side surface of the seal ring 14 that faces the first groove side surface 61. The second opposing side surface 32 is the side surface of the seal ring 14 that faces the second groove side surface 62. That is, the seal ring 14 has a first opposing side surface 31 that faces the first groove side surface 61, which is the side surface of the mounting groove 16.

[0079] As shown in Figure 8, the valve unit 10 is configured such that the first opposing side surface 31 can abut against the inner circumferential side surface 63. The inner circumferential side surface 63 is the portion of the first groove side surface 61 that is radially inward from the recess 21.

[0080] More specifically, Figure 8 shows the first diameter D1, the second diameter D2, the third length L3, and the fourth length L4. The first diameter D1 is the diameter of the portion of the inner wall surface 4 that defines the valve chamber body 6. The second diameter D2 is the diameter of the large diameter portion 12. The third length L3 is the thickness of the seal ring 14 in the radial direction.

[0081] The fourth length L4 is the distance between the bottom of the recess 21 and the inner wall surface 4 when the large-diameter portion 12 and the seal ring 14 are located in the valve chamber body 6, and the portion of the large-diameter portion 12 with the recess 21 is furthest from the inner wall surface 4. In Figure 8, the large-diameter portion 12 and the seal ring 14 are located in the valve chamber body 6. Also, the opposing portion 12a of the large-diameter portion 12, which is the portion opposite to the portion with the recess 21 (in other words, the portion opposite to the portion with the recess 21), is in contact with the inner wall surface 4. That is, the state shown in Figure 8 is the state in which the portion of the large-diameter portion 12 with the recess 21 is furthest from the inner wall surface 4. Therefore, in Figure 8, the second central axis P2 is offset with respect to the first central axis P1 in the direction that the recess 21 moves away from the inner wall surface 4.

[0082] Furthermore, the fourth length L4 is equal to the sum of the length obtained by subtracting the second diameter D2 from the first diameter D1, and the first length L1.

[0083] Furthermore, in this embodiment, the valve unit 10 is configured such that the third length L3 is greater than the fourth length L4. This allows the first opposing side surface 31 to contact the inner circumferential side surface 63 regardless of the position of the large diameter portion 12 (valve body 11) in the radial direction. As a result, the sealing function of the seal ring 14 can be ensured regardless of the position of the large diameter portion 12 (valve body 11) in the radial direction. Although not particularly limited, the third length L3 is preferably 1.05 times or more the fourth length L4.

[0084] Thus, the valve unit 10 is configured such that the first opposing side surface 31 can abut against the portion of the first groove side surface 61 that is radially inward from the recess 21.

[0085] According to the configuration described above, when fluid is introduced between the seal ring 14 and the bottom of the mounting groove 16, more fluid is introduced to the area where the introduction portion 20 is provided than to other parts. Furthermore, the introduction portion 20 is located in a region opposite to the region where the joint portion 18 is located, in line with respect to the axial direction Q.

[0086] As a result, a large amount of fluid is introduced between the seal ring 14 and the bottom of the mounting groove 16 in the region of the mounting groove 16 opposite to the joint portion 18 of the seal ring 14. Consequently, the direction of misalignment of the seal ring 14 is such that the portion of the seal ring 14 included in the region where the joint portion 18 is located (the portion on the joint portion 18 side) approaches the bottom of the mounting groove 16. Therefore, it is possible to avoid a situation in which the joint portion 18 expands due to the fluid pressure from the inner circumference and protrudes (overflows) to the outer circumference.

[0087] Therefore, according to the configuration described above, a valve unit 10 can be realized that can avoid situations in which the seal ring 14 comes off the valve body 11 and in which the seal ring 14 gets caught.

[0088] [Other Embodiments] (1) As shown in Figure 9, the valve body 11 may have a plurality of inlet portions 20. As shown in Figure 9, it is preferable that the plurality of inlet portions 20 are arranged symmetrically with respect to the first straight line T1.

[0089] Although not particularly limited, in the example shown in Figure 9, five introduction portions 20 (recesses 21) are provided. One of the five introduction portions 20 is provided at the location where the joint opposing portion 19 is located. The remaining four introduction portions 20 are arranged such that two introduction portions 20 are located on one side and two on the other side of the first straight line T1. The number of introduction portions 20 provided may be any number of two or more.

[0090] (2) As shown in Figures 10 and 11, the recess 21 does not have to extend to the first end face 23. This recess 21 communicates with the mounting groove 16, as in the above embodiment. The axial width Q of this recess 21 is narrower than the axial width Q of the recess 21 in the above embodiment (see Figures 3 and 5). The comparison cross section in this configuration is the VI-VI cross section in Figure 11. The view of the VI-VI cross section in Figure 11 is the same as that of Figure 6 described above. Therefore, the above explanation regarding Figure 6 also applies to the configuration shown in Figures 10 and 11.

[0091] Even with this configuration, fluid can flow into the mounting groove 16 via the recess 21, similar to the embodiment described above. The cross-sectional shape of the recess 21 is not limited to the shape shown in Figure 10 (a shape with right-angle corners). For example, it may be a sloping surface that becomes deeper closer to the first groove side surface 61 (in other words, a shape that cuts at an angle).

[0092] (3) As shown in Figures 12 and 13, the introduction portion 20 may not be composed of a recess 21, but rather of a hole 41 extending in the axial direction Q. This hole 41 is formed from the first groove side surface 61 to the first end surface 23.

[0093] Figure 12 shows the fifth length L5. The fifth length L5 is the length from the outer circumferential surface of the large diameter portion 12 to the bottom of the hole 41 (in other words, the inner end of the hole 41 in the radial direction of the valve body 11). The fifth length L5 is shorter than the second length L2.

[0094] The fifth length L5 is preferably 10 to 70% of the second length L2 (particularly 10 to 60%, more preferably 10 to 50%). This allows fluid to flow into the mounting groove 16 through the hole 41 while ensuring a seal between the mounting groove 16 and the seal ring 14.

[0095] (4) If the direction of fluid flow can be switched between the direction from the input passage 8 to the output passage 9 and the direction from the output passage 9 to the input passage 8, it is preferable that the mounting groove 16 (seal ring 14) has recesses 21 (introductory portion 20) not only on the first groove side surface 61 side but also on the second groove side surface 62 side, as shown in Figures 14 and 15.

[0096] In the examples shown in Figures 14 and 15, recesses 21 (introductory portions 20) are provided on both sides of the mounting groove 16 (seal ring 14) in the axial direction Q. In this case, the second groove side surface 62 corresponds to the "groove side surface" according to the present invention. Also, the second opposing side surface 32 corresponds to the "opposing side surface" according to the present invention.

[0097] With this configuration, regardless of the direction of fluid flow, the recess 21 (inlet 20) is present on the upstream side of the mounting groove 16 (seal ring 14) in the direction of fluid flow. Therefore, regardless of the direction of fluid flow, fluid can flow into the mounting groove 16 via the recess 21, similar to the above embodiment.

[0098] Furthermore, the position, shape, and size of the recess 21 on the second groove side surface 62 may be the same as or different from the recess 21 in the above embodiment. Also, the positions, shapes, and sizes of the two recesses 21 on the first groove side surface 61 and the second groove side surface 62 may be the same as or different from each other.

[0099] (5) As shown in Figure 16, the seal ring 14 may have a plurality of protrusions 42. Each protrusion 42 protrudes toward the inner circumference.

[0100] With this configuration, a gap is likely to form between the inner circumferential surface of the seal ring 14 and the groove bottom 60. As a result, the fluid introduced through the recess 21 (inlet 20) is likely to enter the space between the inner circumferential surface of the seal ring 14 and the groove bottom 60. Consequently, misalignment of the seal ring 14 due to the inflow of fluid through the recess 21 becomes more certain. This makes it possible to more reliably avoid situations in which the seal ring 14 detaches from the valve body 11 or becomes jammed.

[0101] (6) The valve body 11 may be provided with a rotation restricting portion that restricts the circumferential rotation of the seal ring 14. The rotation restricting portion may consist of a projection and a receiving portion that receives the projection. The projection may be provided on the seal ring 14 and the receiving portion may be provided on the valve body 11.

[0102] (7) When multiple introduction sections 20 are provided, it is preferable that all introduction sections 20 are provided in the first region R1. In other words, it is preferable that the introduction sections 20 are provided only in the first region R1 of the first region R1 and the second region R2. This ensures that the joint section 18 is reliably drawn inward by the introduction of fluid through each introduction section 20.

[0103] However, the present invention is not limited thereto. Some of the multiple introduction sections 20 may be provided in the second region R2.

[0104] (8) The length of the recess 21 in the circumferential direction is preferably 5% or less of the circumference of the large diameter portion 12 (valve body 11) (circumferential length of the outer surface). If the length of the recess 21 in the circumferential direction is longer than 5% of the circumference of the large diameter portion 12 (valve body 11), the seal ring 14 is more likely to come off the mounting groove 16, which can lead to problems such as overloading or malfunction of the spool valve 1, or damage to the seal ring 14. Note that the "length of the recess 21" here refers to the length of a single recess 21, and not the sum of the lengths of multiple recesses 21.

[0105] However, even if the length of the recess 21 in the circumferential direction is longer than 5% of the circumference of the large-diameter portion 12 (valve body 11), as long as the first length L1 is 75% or less of the third length L3, the seal ring 14 can be prevented from coming off the mounting groove 16.

[0106] (9) An elastic backup ring may be mounted in the mounting groove 16, positioned on the inner circumference side of the seal ring 14. Even when such a backup ring is provided, fluid can be introduced by the introduction portion 20, as in the above embodiment, and the direction of misalignment of the seal ring 14 is such that the portion of the seal ring 14 included in the region on the side where the joint portion 18 is located (the portion on the joint portion 18 side) approaches the bottom of the mounting groove 16. Therefore, the situation in which the seal ring 14 comes off the valve body 11 and the situation in which the seal ring 14 gets caught can be avoided.

[0107] (10) The introduction portion 20 may be provided in a location other than the location where the joint facing portion 19 is located in the first region R1.

[0108] (11) The recess depth of the recess 21 may be deeper than the depth of the mounting groove 16.

[0109] Furthermore, the configurations disclosed in the above-described embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. In addition, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention.

[0110] This invention is applicable to valve units.

[0111] 1: Spool valve 4: Inner wall surface 5: Valve chamber 10: Valve unit 11: Valve body 14: Seal ring 16: Mounting groove 18: Joint portion 19: Opposing joint portion 20: Inlet portion 21: Recess 31: First opposing side surface (opposing side surface) 61: First groove side surface (groove side surface) PR: Center position Q: Axial direction T1: First straight line T2: Second straight line

Claims

1. A valve unit in a spool valve capable of switching between a connected state and a blocked state for a fluid passage, comprising: a valve body disposed in a valve chamber surrounded by a cylindrical inner wall surface and configured to be movable in the axial direction of the inner wall surface relative to the inner wall surface; and a seal ring fitted into an annular mounting groove provided on the outer circumference of the valve body and sealing the space between the inner wall surface and the valve body, wherein the seal ring has a joint portion, and the valve body has an introduction portion that can introduce the fluid and communicates with the mounting groove, wherein the introduction portion is located in a region opposite to the region on which the joint portion is located, with reference to a second straight line passing through the center position of the seal ring and the joint portion, in line with respect to the axial direction.

2. The valve unit according to claim 1, wherein the introduction portion is provided on the outer circumference of the valve body and is configured as a recess that is recessed radially inward.

3. The valve unit according to claim 2, wherein the recess depth of the recess is shallower than the depth of the mounting groove.

4. The valve unit according to claim 3, wherein the seal ring has an opposing side surface that faces the groove side surface which is the side surface of the mounting groove, and the opposing side surface is configured to contact a portion of the groove side surface that is radially inward from the recess.

5. The valve unit according to claim 1, wherein the introduction portion is provided at a location in the seal ring where the portion facing the joint portion is located, with respect to the center position.

6. The valve unit according to claim 1, wherein the valve body has a plurality of introduction portions, and the plurality of introduction portions are arranged symmetrically with respect to the first straight line.

7. The valve unit according to any one of claims 1 to 6, further comprising a rotation restricting portion for restricting the circumferential rotation of the seal ring relative to the valve body.

Images