Valve device

Abstract

This valve device is provided with: a housing (10) that forms a fluid channel (F); a fixed disk (20) which is disposed inside the housing and in which is formed at least one channel hole (23) through which a fluid flows; a drive unit (40) that outputs torque; a shaft (50) that rotates around a shaft axis (CL) due to the torque output by the drive unit; and a drive disk (30) that increases and decreases the aperture of the channel hole as the shaft rotates and that slides against the fixed disk so as to rotate around the shaft axis. The fixed disk has a seal surface (21) that faces the drive disk on one side in a direction in which the shaft axis extends. The drive disk has a sliding surface (31) that slides against the seal surface on the other side in the direction in which the shaft axis extends. A central portion of at least one of the seal surface and the sliding surface of the fixed disk and the drive disk has a convex shape, formed so as to protrude toward the other surface.

Description

Valve equipment CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2024-49898, filed on March 26, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a valve device.

[0003] A conventional valve device includes a housing that defines a fluid passage, a fixed disk that defines a passage hole through which the fluid passes, a drive disk that adjusts the opening of the passage hole, and a drive unit that outputs a torque to rotate the drive disk (see, for example, Patent Document 1). In this valve device, the housing is formed with one inlet that guides the fluid into the fluid passage, and two outlets that communicate with the passage hole and allow the fluid to flow out of the fluid passage. The passage hole in the fixed disk is opened or closed depending on the rotational position of the drive disk, which is positioned by the torque of the drive unit, thereby switching the outlet that communicates with the inlet.

[0004] International Publication No. 2014 / 072376

[0005] When the drive disk rotates due to the torque of the drive unit, the drive disk must be pressed against the fixed disk to prevent fluid from leaking between the drive disk and the fixed disk. This generates friction between the drive disk and the fixed disk. Therefore, the drive unit must increase the maximum torque it can output compared to when no friction occurs between the drive disk and the fixed disk.

[0006] Furthermore, as the contact area between the drive disk and the fixed disk increases due to the increase in size of the drive disk and the fixed disk, the frictional force generated between the drive disk and the fixed disk tends to increase. Therefore, the larger the drive disk and the fixed disk, the greater the maximum torque that the drive unit can output.

[0007] However, if the maximum value of the torque that the drive unit can output increases, there is a risk that the drive unit and the valve device will become larger. For this reason, it is desirable to suppress the maximum value of the torque that the drive unit can output.

[0008] In view of the above, an object of the present disclosure is to provide a valve device that can suppress the maximum value of the rotational force that can be output by a drive unit.

[0009] According to one aspect of the present disclosure, a valve device comprises: a housing forming a fluid passage therein for circulating a fluid; a fixed disk arranged inside the housing and having at least one flow path hole formed therein through which the fluid flows; a drive unit that outputs a rotational force; a shaft that rotates about the shaft axis by the rotational force output by the drive unit; and a drive disk that increases or decreases the opening of the flow path hole as the shaft rotates and slides against the fixed disk to rotate about the shaft axis, wherein the fixed disk has a seal surface facing the drive disk on one side in the direction in which the shaft axis extends, and the drive disk has a sliding surface sliding against the seal surface on the other side in the direction in which the shaft axis extends, and the fixed disk and the drive disk have a convex shape in which a central portion of at least one of the seal surfaces and the sliding surfaces protrudes toward the other surface compared to the other portion.

[0010] This reduces the frictional force that occurs in the areas away from the center of each surface, which tends to be large if the center portions of both the sealing surface and the sliding surface do not protrude toward the other surface. Therefore, compared to when the center portions of both the sealing surface and the sliding surface do not protrude toward the other surface, the maximum value of the rotational force that can be output by the drive unit can be reduced.

[0011] 1 is a perspective view of the appearance of the valve device according to the present embodiment; FIG. 2 is a side view of the valve device according to the present embodiment; FIG. 3 is a cross-sectional view taken along III-III in FIG. 2; FIG. 4 is a view of the drive disk according to the present embodiment as viewed from the opposite side to the sliding surface side; FIG. 5 is a view for explaining the lever according to the present embodiment; FIG. 6 is a view showing the appearance of the fixed disk before surface treatment is applied; FIG. 7 is a view showing the appearance of the fixed disk after surface treatment is applied; FIG. 8 is a view for explaining the shape of the fixed disk when not pressed by a compression spring; FIG. 9 is a view for explaining the shapes of the fixed disk and the drive disk when pressed by a compression spring; FIG. 10 is a view for explaining the shapes of the fixed disk and the drive disk when further pressed by a compression spring; FIG. 11 is a view showing a modified example of the drive disk; FIG. 12 is a view showing a modified example of the fixed disk; FIG. 13 is a view showing a modified example of the drive disk; FIG. 14 is a view showing a modified example of the fixed disk and the drive disk; FIG. 15 is a view showing a modified example of the drive disk;

[0012] An embodiment of the present disclosure will be described with reference to FIGS. 1 to 10 . A valve device 1 of this embodiment is applied to a fluid circulation system in which a fluid (in this example, coolant) circulates to regulate the temperature of the cabin and battery of, for example, an electric vehicle or hybrid vehicle. The fluid circulation system circulates coolant through a power source for driving the vehicle, a radiator, a heater core for cabin air conditioning, and a battery. For example, LLC (Long Life Coolant) containing ethylene glycol is used as the coolant. The valve device 1 switches the flow path or adjusts the flow rate of the coolant flowing through the fluid circulation system. In this embodiment, the valve device 1 is configured as a four-way valve.

[0013] 1 and 2, the valve device 1 has a housing 10 that forms a fluid passage F through which a fluid flows. The housing 10 has one inlet port that allows fluid to flow into the fluid passage F from the outside of the valve device 1, and three outlet ports that allow the fluid that has flowed into the fluid passage F to flow out to the outside of the valve device 1. Hereinafter, as shown in FIG. 1 and other figures, the two fluid ports that allow fluid to flow into the fluid passage F will be referred to as first inlet portions 10a, and the three outlet ports that allow fluid to flow out of the fluid passage F will be referred to as first outlet portion 10b, second outlet portion 10c, and third outlet portion 10d.

[0014] First, the configuration of the valve device 1 of this embodiment will be described. As shown in FIGS. 1 to 3 , the valve device 1 of this embodiment includes a fixed disk 20, a drive disk 30, a drive unit 40, a shaft 50, a lever 60, a first torsion spring 70, a second torsion spring 80, and a compression spring 90. The valve device 1 accommodates the fixed disk 20, the drive disk 30, the shaft 50, the lever 60, the first torsion spring 70, the second torsion spring 80, and the compression spring 90 within a housing 10. The valve device 1 also includes a drive unit 40 disposed outside the housing 10. The valve device 1 of this embodiment is configured as a disk valve in which the drive unit 40 rotates the drive disk 30 integrally with the shaft 50 to switch the flow path of the cooling water flowing through the fluid circulation system. Note that the drive unit 40 is omitted from FIG. 3 for clarity.

[0015] In this embodiment, as shown in Figure 3 and other figures, the direction along the shaft axis CL of the shaft 50 is referred to as the axial direction DRa, the direction to one side of the axial direction DRa is referred to as the downward direction DRa1, and the direction opposite the downward direction DRa1 is referred to as the upward direction DRa2. Furthermore, various configurations will be described using the circumferential direction DRc as the direction around the shaft axis CL and the radial direction DRr as the direction perpendicular to the axial direction DRa and extending radially from the shaft axis CL. The circumferential direction DRc is the direction of rotation of the shaft 50 and the drive disk 30, which are rotated by the rotational force supplied from the drive unit 40. Note that the directions shown in Figure 2 and other figures are merely examples and do not limit the installation state of the valve device 1 of the present disclosure.

[0016] The housing 10 is a non-rotating member. The housing 10 is formed, for example, from a resin material. Specifically, the housing 10 has a main body 11 having a cylindrical shape with a bottom and a main body cover 12 that closes the open side of the main body 11. In this embodiment, the main body 11 and the main body cover 12 are molded, for example, by injection molding, in which a resin material is poured into a mold and hardened into a desired shape.

[0017] The main body 11 has a bottom wall 13 that forms the bottom surface and a cylindrical side wall 14 that surrounds the shaft axis CL in the circumferential direction DRc. The bottom wall 13 and the side wall 14, together with the main body cover 12, form a fluid passage F. The bottom wall 13 and the side wall 14 are configured as an integrally molded product.

[0018] The main body 11 has a first inlet 10a connected to the outer peripheral surface of the side wall 14. The main body 11 also has a first outlet 10b and a second outlet 10c connected to the outer peripheral surface of the bottom wall 13, and a third outlet 10d connected to the lower surface of the bottom wall 13 in the downward direction DRa1.

[0019] The first inlet portion 10a, the first outlet portion 10b, the second outlet portion 10c, and the third outlet portion 10d are configured as tubular members formed to allow fluid to flow therethrough. The first inlet portion 10a, the first outlet portion 10b, and the second outlet portion 10c are formed to protrude from the housing 10 along the radial direction DRr. The third outlet portion 10d is formed to protrude from the housing 10 along the axial direction DRa.

[0020] The side wall portion 14 has a cylindrical shape that surrounds the upper fluid passage Fu, which is located on the upper direction DRa2 side of the fixed disk 20 in the fluid passage F, in the circumferential direction DRc and extends along the axial direction DRa. The side wall portion 14 is formed so that its axis is coaxial with the shaft axis CL. An engagement groove (not shown) that receives an engagement protrusion (not shown) of the fixed disk 20 is formed on the inner peripheral surface of the side wall portion 14. The opening side of the side wall portion 14 is closed by the body cover portion 12.

[0021] The body cover 12 is a lid that closes the open side of the body 11. The body cover 12 is attached to the body 11 by fitting it inside the body 11 from the open side of the body 11. That is, the upper fluid passage Fu formed by the inner circumferential surface of the side wall 14 is closed by the body cover 12. The body cover 12 is attached to the body 11 together with the drive unit 40 by, for example, tapping screws S.

[0022] An O-ring 162 that closes the gap between the main body 11 and the main body cover 12 is disposed between the inner peripheral surface of the side wall 14 and the outer peripheral surface of the main body cover 12. The O-ring 162 is made of, for example, urethane rubber, which is an annular elastic body, and is configured to be compressed and elastically deformable when sandwiched between the main body 11 and the main body cover 12.

[0023] The bottom wall portion 13 is a portion on which the fixed disk 20 is installed and which supports the downward direction DRa1 side of the axial center portion 51 (described later) of the shaft 50. The bottom wall portion 13 also forms a fluid passage F that guides the fluid that has flowed in from the first inlet portion 10a to the first outlet portion 10b, the second outlet portion 10c, and the third outlet portion 10d.

[0024] 3, the bottom wall portion 13 has a mounting surface 131 on the upward DRa2 side for placing the fixed disk 20. The bottom wall portion 13 also has a bearing hole 132 that supports the axial portion 51 and a lower fluid passage Fd that is located on the downward DRa1 side of the fixed disk 20 in the fluid passage F. The downward DRa1 side of the axial portion 51 is fitted into the bearing hole 132. The bearing hole 132 rotatably supports the axial portion 51.

[0025] The lower fluid passage Fd is divided into three sections by the bottom wall portion 13, and each section communicates with one of the first outlet portion 10b, the second outlet portion 10c, and the third outlet portion 10d. Although not shown, the bottom wall portion 13 is provided with a plate-shaped partition portion that divides the lower fluid passage Fd into a passage that communicates with the first outlet portion 10b, a passage that communicates with the second outlet portion 10c, and a passage that communicates with the third outlet portion 10d. The partition portion is provided to cross the lower fluid passage Fd along the radial direction DRr, and divides the lower fluid passage Fd into three sections in the circumferential direction DRc.

[0026] The mounting surface 131 is formed to extend in a flat plane in the radial direction DRr and the circumferential direction DRc. A gasket groove 133 is formed in the mounting surface 131 to accommodate a gasket 15 that seals the gap between the fixed disk 20 and the mounting surface 131. The gasket 15 is made of, for example, an elastically deformable rubber member, and is formed in a shape that corresponds to the lower fluid passage Fd.

[0027] The fixed disk 20 is a sealing member that seals the gap between the bottom wall 13 and the drive disk 30. The fixed disk 20 is made of a thin, approximately disk-shaped member with its thickness direction aligned with the axial direction DRa, and its outer diameter is slightly smaller than the inner diameter of the side wall 14. The fixed disk 20 is also arranged so that its axis is coaxial with the shaft axis CL. The fixed disk 20 is also arranged within the housing 10, pressed by the drive disk 30, which is biased by a compression spring 90.

[0028] The fixed disk 20 has a seal surface 21 that contacts the drive disk 30 and a support surface 22 that contacts the installation surface 131. The seal surface 21 is an opposing surface that faces a sliding surface 31 of the drive disk 30, which will be described later, and comes into contact with the sliding surface 31.

[0029] 3, the fixed disk 20 is formed with three flow path holes 23 that communicate with the lower fluid passage Fd, allowing fluid to pass through the flow path holes 23. The fixed disk 20 is formed with a fixed disk hole 24 in its approximate center, through which the shaft 50 is inserted, and has fitting protrusions (not shown) formed on its outer circumferential surface. The fitting protrusions are fitted into fitting grooves (not shown) formed on the inner circumferential surface of the side wall portion 14, thereby restricting rotation of the fixed disk 20 in the circumferential direction DRc.

[0030] The fixed disk 20 is made of a material that has a smaller coefficient of linear expansion, superior wear resistance, and a smaller coefficient of friction than the constituent material of the housing 10. For example, the fixed disk 20 is made of a high-hardness material that is harder than the housing 10 and the drive disk 30. The fixed disk 20 is made of a metal (for example, SUS, i.e., Steel Use Stainless) that is harder than resin.

[0031] The sealing surface 21 and the support surface 22 are formed to extend in a planar shape along the radial direction DRr and the circumferential direction DRc, and are substantially perpendicular to the axial direction DRa and substantially parallel to each other in the radial direction DRr.

[0032] The three flow path holes 23 are formed at positions away from the fixed disk hole 24 so as not to overlap with the fixed disk hole 24. The flow path holes 23 are formed, for example, in a sector shape (i.e., a fan shape). The flow path holes 23 are communication paths that connect the upper fluid path Fu and the lower fluid path Fd.

[0033] The drive disk 30 is a valve element that increases or decreases the aperture of the flow passage hole 23 of the fixed disk 20 by rotating about the shaft axis CL in accordance with the rotation of the shaft 50. As shown in FIGS. 3 and 4 , the drive disk 30 is configured as a substantially disk-shaped member with its thickness direction aligned with the axial direction DRa, and its outer diameter is smaller than the inner diameter of the side wall portion 14. The drive disk 30 is disposed so that its rotation axis is coaxial with the shaft axis CL. The drive disk 30 is disposed within the housing 10 while being biased by a compression spring 90.

[0034] As shown in Fig. 3, the drive disk 30 faces the seal surface 21 of the fixed disk 20 and has a sliding surface 31 that slides against the seal surface 21. As shown in Fig. 4, the drive disk 30 has a drive disk hole 32 formed in the approximate center, through which the shaft 50 is inserted, and two press-fit grooves 33 into which levers 60 (described later) are press-fit. The press-fit grooves 33 are formed at positions away from the drive disk hole 32 of the drive disk 30 so as not to overlap with the drive disk hole 32. The press-fit grooves 33 are formed at positions closer to the outer circumferential surface than to the central axis of the drive disk 30.

[0035] The drive disk 30 is also formed with one through-hole 34 that penetrates the drive disk 30 in the axial direction DRa, allowing fluid to pass through the through-hole 34. The through-hole 34 is formed at a position that allows it to overlap with each of the three flow path holes 23 of the fixed disk 20 in the axial direction DRa when the drive disk 30 is rotated around the shaft axis CL.

[0036] The drive disk 30 is made of a material that has a smaller coefficient of linear expansion, superior wear resistance, and a smaller coefficient of friction than the material constituting the housing 10. For example, the drive disk 30 is made of a high-hardness resin that is harder than the housing 10.

[0037] The sliding surface 31 is a surface of the drive disk 30 on the downward direction DRa1 side, facing the seal surface 21. The sliding surface 31 slides against the seal surface 21 of the fixed disk 20 when the drive disk 30 rotates in conjunction with the rotation of the shaft 50. The sliding surface 31 is formed to extend flatly in the radial direction DRr and the circumferential direction DRc. The sliding surface 31 is substantially perpendicular to the axial direction DRa and substantially parallel to the radial direction DRr.

[0038] Returning to FIG. 2 , the drive unit 40 is provided on the upper side DRa2 of the main body cover 12. The drive unit 40 is a device for outputting a rotational force for rotating the shaft 50. The drive unit 40 has the shaft 50, a motor (not shown) as a drive source for rotating the shaft 50, and a gear unit (not shown) that transmits the output of the motor to the shaft 50. The motor may be, for example, a servo motor, a stepping motor, or a brushless motor. The gear unit may be, for example, a gear mechanism including a helical gear or a spur gear.

[0039] The shaft 50 is a rotating shaft that rotates about the shaft axis CL by the rotational force output by the drive unit 40. As shown in Fig. 3, the shaft 50 is rotatably supported on both sides in the axial direction DRa by the housing 10. Specifically, the downward DRa1 side of the shaft 50 is rotatably supported by a bearing (not shown) provided in the bearing hole 132, and the upward DRa2 side of the shaft 50 is rotatably supported by a bearing portion 41 provided in the main body cover portion 12. These bearings may be plain bearings, ball bearings, or the like.

[0040] The shaft 50 includes a metal axial center portion 51 and a resin holder portion 52 connected to the axial center portion 51. The axial center portion 51 and the holder portion 52 are connected to each other so as to be rotatable together. The axial center portion 51 and the holder portion 52 are insert-molded products molded integrally by insert molding.

[0041] The axial center portion 51 includes the shaft axis CL of the shaft 50 and extends along the axial direction DRa. The axial center portion 51 is made of a metal rod member to ensure straightness. The axial center portion 51 is connected to the holder portion 52 on the upward direction DRa2 side. The axial center portion 51 penetrates the fixed disk 20 and the drive disk 30.

[0042] The holder portion 52 has a cylindrical shape with a bottom that opens downward in the direction DRa1. The axial center portion 51 of the holder portion 52 is connected to the inside of the tip portion on the upward direction DRa2 side. The tip portion of the holder portion 52 that protrudes outside the body cover portion 12 is connected to the drive unit 40. This allows the rotational force output by the drive unit 40 to be transmitted to the shaft 50. The rotational force output by the drive unit 40 is transmitted to the drive disk 30 via the shaft 50, the lever 60, and the second torsion spring 80. The shaft 50 is connected to the drive disk 30 via the lever 60 and the second torsion spring 80.

[0043] The lever 60 is a connecting member that connects the drive disk 30 to the shaft 50. The lever 60 is fixed to the drive disk 30 and connects the drive disk 30 and the shaft 50 so that they can rotate together while the drive disk 30 is displaceable in the axial direction DRa of the shaft 50. As shown in FIG. 5 , the lever 60 has two press-fit portions 61 formed on a surface facing the drive disk 30. The two press-fit portions 61 protrude toward the drive disk 30 so as to be press-fittable into two press-fit grooves 33 formed in the drive disk 30, respectively. The press-fit portions 61 are press-fitted into the press-fit grooves 33 of the drive disk 30, and the lever 60 is fixed to the drive disk 30. In this way, the press-fit grooves 33 into which the press-fit portions 61 of the lever 60 are press-fitted to connect the lever 60 and the drive disk 30 function as a connecting portion.

[0044] As shown in FIG. 3 , the first torsion spring 70 is a spring that biases the shaft 50 in the circumferential direction DRc relative to the housing 10. For example, a torsion coil spring that is elastically deformable in the circumferential direction DRc can be used as the first torsion spring 70. The first torsion spring 70 is disposed between the housing 10 and the shaft 50. The first torsion spring 70 is used in a state in which it is twisted and elastically deformed in the circumferential direction DRc. The first torsion spring 70 is disposed between the housing 10 and the shaft 50 in a state in which it is compressed in the circumferential direction DRc, with one end of the first torsion spring 70 in contact with the housing 10 and the other end of the first torsion spring 70 in contact with the holder portion 52 of the shaft 50.

[0045] The biasing force of the first torsion spring 70 is transmitted as a rotational force from the gear portion of the drive unit 40 to the motor via the shaft 50. Therefore, by disposing the first torsion spring 70 between the housing 10 and the shaft 50, rattle in the circumferential direction DRc between the drive unit 40 and the shaft 50 is suppressed.

[0046] The second torsion spring 80 is a spring that biases the shaft 50 in the circumferential direction DRc relative to the housing 10. The second torsion spring 80 may be, for example, a torsion coil spring that is elastically deformable in the circumferential direction DRc. The second torsion spring 80 is disposed between the lever 60 and the shaft 50. The second torsion spring 80 is used in a state in which it is twisted and elastically deformed in the circumferential direction DRc. The second torsion spring 80 is disposed between the lever 60 and the shaft 50 in a state in which it is compressed in the circumferential direction DRc, with one end of the second torsion spring 80 in contact with the lever 60 and the other end of the second torsion spring 80 in contact with the holder portion 52 of the shaft 50.

[0047] As a result, the second torsion spring 80 generates a biasing force that biases the drive disk 30 to one side in the circumferential direction DRc due to its own elastic deformation. When the rotational force generated by the drive unit 40 is transmitted to the shaft 50, the rotational force is transmitted to the drive disk 30 via the second torsion spring 80 and the lever 60. Then, as the shaft 50 rotates, the drive disk 30 rotates integrally with the shaft 50 about the shaft axis CL.

[0048] The compression spring 90 is a biasing portion that biases the drive disk 30 toward the fixed disk 20. The compression spring 90 may be, for example, a compression coil spring that is elastically deformable in the axial direction DRa of the shaft 50. The compression spring 90 is disposed inside the housing 10 in a compressed state in the axial direction DRa, with its end on the downward direction DRa1 side contacting the lever 60 and its end on the upward direction DRa2 side contacting the holder portion 52 of the shaft 50. The compression spring 90 is not fixed to at least one of the drive disk 30 and the shaft 50 so that it does not function as the first torsion spring 70 or the second torsion spring 80.

[0049] The compression spring 90 presses the drive disk 30 against the fixed disk 20, thereby maintaining contact between the seal surface 21 of the fixed disk 20 and the sliding surface 31 of the drive disk 30. This contact state is a state in which the seal surface 21 of the fixed disk 20 and the sliding surface 31 of the drive disk 30 are in surface contact. In other words, the valve device 1 can maintain the drive disk 30 in contact with the fixed disk 20.

[0050] The compression spring 90 is disposed so as to surround the shaft axis CL of the shaft 50. In other words, the shaft 50 is disposed inside the compression spring 90. This prevents the load of the compression spring 90 on the drive disk 30 from being biased in the circumferential direction DRc of the shaft 50, making it easier to maintain contact between the seal surface 21 and the sliding surface 31.

[0051] The compression spring 90 is disposed inside the holder portion 52 and is capable of pressing the central periphery of the surface of the lever 60 on the upward DRa2 side in the downward DRa1 direction.

[0052] Next, a description will be given of the operation of the valve device 1 of this embodiment. Fluid flows into the fluid passage F of the valve device 1 through the first inlet 10a. The fluid that has flowed into the fluid passage F flows out from one of the first outlet 10b, the second outlet 10c, and the third outlet 10d, depending on the rotational position of the drive disk 30.

[0053] Specifically, when the through-hole 34 is positioned at a rotational position where it communicates with one of the three flow path holes 23, the fluid flows out from one of the first outlet portion 10b, the second outlet portion 10c, and the third outlet portion 10d via the lower fluid passage Fd that communicates with that flow path hole 23. In other words, the outlet portion from which the fluid flows out, among the first outlet portion 10b, the second outlet portion 10c, and the third outlet portion 10d, is determined by the rotational position of the drive disk 30. The drive disk 30 rotates by the rotational force output by the drive unit 40, and the rotational position is maintained by that rotational force.

[0054] Incidentally, when the drive disk 30 is rotated by the rotational force of the drive unit 40, it is desirable to rotate the sliding surface 31 while pressing it against the seal surface 21 in order to prevent fluid from leaking from the gap between the seal surface 21 and the sliding surface 31. For this reason, the valve device 1 of this embodiment is provided with a compression spring 90 that presses the sliding surface 31 against the seal surface 21, thereby maintaining contact between the seal surface 21 and the sliding surface 31. When the drive disk 30 is rotated by the rotational force of the drive unit 40, the seal surface 21 and the sliding surface 31 slide against each other.

[0055] For this reason, when the drive disk 30 is rotated by the rotational force of the drive unit 40, a frictional force is generated between the seal surface 21 and the sliding surface 31. Therefore, the valve device 1 needs to employ a drive unit 40 that can output a larger maximum value of rotational force than when no frictional force is generated between the seal surface 21 and the sliding surface 31.

[0056] Furthermore, the larger the outer diameters of fixed disk 20 and drive disk 30, the larger the contact area between seal surface 21 and sliding surface 31. In such cases, the frictional force generated between seal surface 21 and sliding surface 31 tends to increase. For this reason, the larger the outer diameters of fixed disk 20 and drive disk 30, the more necessary it is to employ a drive unit 40 that can output a large maximum torque.

[0057] However, a drive unit 40 with a large maximum value of the torque that can be output may result in an increase in the size of the drive unit 40 and the size of the valve device 1. For this reason, it is desirable to suppress the frictional force that occurs between the seal surface 21 and the sliding surface 31 and to suppress the maximum value of the torque that can be output by the drive unit 40.

[0058] For this reason, in the valve device 1 of this embodiment, a friction force reduction structure is provided on at least one of the fixed disk 20 and the drive disk 30 to reduce the friction force generated between the seal surface 21 and the sliding surface 31. Specifically, the fixed disk 20 of this embodiment has a structure in which the central portion of the seal surface 21 has a convex shape that protrudes more toward the sliding surface 31 than the other portions. This makes it possible to reduce the friction force generated between the seal surface 21 and the sliding surface 31 when the drive disk 30 is rotated by the rotational force of the drive unit 40.

[0059] The specific shape of the fixed disk 20 will be described with reference to FIGS. 6 and 7 . As described above, the fixed disk 20 of this embodiment is formed from a thin, approximately disk-shaped member. The fixed disk 20 has a warped shape due to internal stress generated in the fixed disk 20 by performing a surface treatment on the protruding surface, i.e., the seal surface 21 facing the sliding surface 31 of the drive disk 30. This allows the shape of the fixed disk 20 to be a spherical shape in which the central portion of the seal surface 21 protrudes more toward the sliding surface 31 than the other portions. Furthermore, the seal surface 21 of the fixed disk 20, which is surface-treated, is covered with a coating material 25.

[0060] Here, Fig. 6 shows the appearance of the fixed disk 20 before surface treatment, and Fig. 7 shows the appearance of the fixed disk 20 after surface treatment. As shown in Fig. 6, the fixed disk 20 before surface treatment is in the form of a thin plate, and the sealing surface 21 and the support surface 22 are planar and parallel to each other. In other words, in the fixed disk 20 before being placed in the valve device 1, the support surface 22, which is located on one side of the axial direction DRa when the fixed disk 20 is installed in the valve device 1, and the sealing surface 21, which is located on the other side of the axial direction DRa, are each approximately parallel to each other.

[0061] In contrast, as shown in Fig. 7 , after the surface treatment, the fixed disk 20 has the sealing surface 21 covered with the coating material 25, resulting in a curved, warped shape for the sealing surface 21 and the support surface 22. That is, when the fixed disk 20 is installed in the valve device 1, the support surface 22 located on one side of the axial direction DRa and the sealing surface 21 located on the other side each protrude toward the sliding surface 31. The sealing surface 21 gradually protrudes toward the sliding surface 31 from the outer periphery toward the center, with the central portion being the largest in warp.

[0062] The coating material 25 used in the surface treatment to form the central portion of the seal surface 21 in a convex shape toward the sliding surface 31 can have a smaller Young's modulus than the fixed disk 20 that constitutes the seal surface 21 covered by the coating material 25. Various surface treatment methods can be used to form the central portion of the seal surface 21 in a convex shape toward the sliding surface 31. For example, a DLC coating (i.e., diamond-like carbon coating) can be used to cover the seal surface 21 with a thin film of coating material 25 containing carbon as the main component. DLC coating can be performed using methods such as ion plating, PVD (i.e., physical vapor deposition), and CVD (i.e., chemical vapor deposition).

[0063] As a result, the fixed disk 20 after the surface treatment can be warped by several μm to several tens of μm compared to before the surface treatment. Note that, unlike the fixed disk 20, the drive disk 30 of this embodiment is not surface-treated to give the drive disk 30 a warped shape. Therefore, before the drive disk 30 is placed in the valve device 1, the sliding surface 31 of the drive disk 30 is formed in a flat shape extending along the radial direction DRr. In addition, in Figure 7 and Figure 8 (described later), the magnitude of the warp is depicted as being larger than the actual warp to make it easier to understand that the fixed disk 20 has a warped shape.

[0064] The fixed disk 20 formed in this manner has the sliding surface 31 pressed against the seal surface 21 by the drive disk 30, which is pressed by the compression spring 90. As the seal surface 21 is pressed against the sliding surface 31, the fixed disk 20 is deformed and is disposed in the valve device 1 with substantially the entire seal surface 21 in contact with the sliding surface 31.

[0065] The shape of the fixed disc 20 that is deformed when placed inside the valve device 1 will be described with reference to Figures 8 to 10. Note that in Figures 8 to 10, the housing 10, shaft 50, first torsion spring 70, second torsion spring 80, and coating material 25 are omitted to make the shape of the fixed disc 20 easier to understand.

[0066] 8 shows a state in which the drive disc 30 is not yet pressed by the compression spring 90. When the fixed disc 20 is disposed in the valve device 1, the drive disc 30 with the lever 60 attached is disposed on the upward direction DRa2 side of the fixed disc 20 with the axial center portion 51 of the shaft 50 inserted into the fixed disc hole 24.

[0067] 8 , in the fixed disk 20 in which the seal surface 21 is formed to protrude upward in the DRa2 direction, only the central portion of the seal surface 21 contacts the sliding surface 31, and the portion away from the central portion in the radial direction DRr does not contact the sliding surface 31. In addition, in the fixed disk 20, the central portion of the support surface 22 does not contact the installation surface 131, and only the portion close to the outer circumferential surface away from the central portion in the radial direction DRr is supported by the installation surface 131.

[0068] 9 , the lever 60 and the drive disk 30 are pushed by the compression spring 90 from the upward direction DRa2 toward the downward direction DRa1, whereby the seal surface 21 of the fixed disk 20 is pressed against the sliding surface 31 of the drive disk 30. This causes the fixed disk 20 to deform, and substantially the entire support surface 22 is supported by the installation surface 131.

[0069] Then, as the lever 60 and the drive disk 30 are further pressed by the compression spring 90, the seal surface 21 of the fixed disk 20 is further pressed against the sliding surface 31 of the drive disk 30. As a result, the sliding surface 31 of the drive disk 30 assumes a shape that follows the shape of the seal surface 21, which has a spherical shape with a protruding central portion, as shown in FIG. 10 . In other words, the sliding surface 31 assumes a spherical shape with a curvature that is approximately equal to the curvature of the seal surface 21. This maintains contact between the seal surface 21 and the sliding surface 31.

[0070] As described above, the lever 60 of this embodiment is coupled to the drive disk 30 by having the press-fit portion 61 press-fit into the press-fit groove 33 of the drive disk 30. The press-fit groove 33 is formed at a position closer to the outer circumferential surface than the central axis of the drive disk 30. Therefore, the biasing force of the compression spring 90 pressing the central portion of the surface of the lever 60 facing the upward direction DRa2 is transmitted via the lever 60 to the central portion of the drive disk 30 as well as to the portion of the drive disk 30 where the press-fit groove 33 is formed, which is closer to the outer circumferential surface. That is, the lever 60 presses the central portion and a portion of the drive disk 30 close to the outer circumferential surface with the biasing force of the compression spring 90. Therefore, when the sliding surface 31 of the drive disk 30 presses the seal surface 21 of the fixed disk 20, the biasing force of the compression spring 90 is transmitted to the central portion of the seal surface 21 as well as to the portion close to the outer circumferential surface.

[0071] Therefore, the shape of the sliding surface 31 is likely to follow the shape of the sealing surface 21. This makes it easier to maintain the contact state between the sealing surface 21 and the sliding surface 31.

[0072] Next, the frictional force generated between seal surface 21 and sliding surface 31 when fixed disk 20 has a convex shape formed by the central portion of seal surface 21 protruding toward sliding surface 31 will be described.

[0073] When the drive disk 30 rotates due to the rotational force of the drive unit 40, the sliding surface 31 slides against the seal surface 21, generating a frictional force between the seal surface 21 and the sliding surface 31. This frictional force is generated when the drive disk 30 rotates in a state in which the sliding surface 31 is biasing the seal surface 21 due to the biasing force generated by the compression spring 90.

[0074] When the force with which the sliding surface 31 urges the seal surface 21 is constant over the entire seal surface 21, the frictional force generated by the rotation of the drive disk 30 increases the farther the portion is from the rotation axis of the drive disk 30. On the other hand, when the force with which the sliding surface 31 urges the seal surface 21 is constant over the entire seal surface 21, the frictional force generated by the rotation of the drive disk 30 decreases the farther the portion is from the rotation axis of the drive disk 30.

[0075] That is, when the force with which the sliding surface 31 urges the seal surface 21 is constant over the entire seal surface 21, the frictional force generated between the seal surface 21 and the sliding surface 31 increases the farther the seal surface 21 is from the shaft axis CL. Therefore, the frictional force generated between the seal surface 21 and the sliding surface 31 is less affected by the frictional force in areas closer to the shaft axis CL, and is more affected by the frictional force in areas farther from the shaft axis CL.

[0076] In contrast, fixed disk 20 of this embodiment has a convex shape formed such that the central portion of seal surface 21 protrudes toward sliding surface 31. Therefore, the reaction force that sliding surface 31 receives when sliding surface 31 presses against seal surface 21 is greatest at the central portion of sliding surface 31 and becomes smaller as the distance from the central portion of sliding surface 31 toward the outer circumferential surface increases in the radial direction DRr.

[0077] Therefore, of the frictional forces generated between the seal surface 21 and the sliding surface 31, the frictional force around the centers of the respective surfaces is large, but the frictional force generated in the portions away from the centers of the respective surfaces in the radial direction DRr can be reduced. In other words, if the central portion of the seal surface 21 is not formed so as to protrude toward the sliding surface 31, the frictional force generated in the portions away from the central portions of the seal surface 21 and the sliding surface 31 in the radial direction DRr, which tends to be large, can be reduced. As a result, of the frictional forces generated between the seal surface 21 and the sliding surface 31, the frictional force generated in the portions farther from the shaft axis CL, which has a greater influence, can be suppressed.

[0078] This makes it possible to suppress the maximum value of the rotational force that can be output by the drive unit 40 compared to a shape in which the central portion of the seal surface 21 is not formed so as to protrude toward the sliding surface 31 .

[0079] Furthermore, in the drive disk 30 of this embodiment, the sliding surface 31 is pressed against the sealing surface 21 and is shaped to follow the shape of the sealing surface 21. Therefore, a reaction force is generated in the central portion of the sliding surface 31 as it tries to return to its deformed state after being pressed, and the reaction force received by the central portion of the sliding surface 31 becomes even greater.

[0080] Therefore, of the frictional forces generated between the seal surface 21 and the sliding surface 31, the frictional forces at the central portions of the seal surface 21 and the sliding surface 31 can be increased, and the frictional forces generated at the portions away from the central portions in the radial direction DRr can be reduced. This reduces the frictional forces generated at the portions away from the central portions of the seal surface 21 and the sliding surface 31 in the radial direction DRr, and further reduces the maximum value of the rotational force that can be output by the drive unit 40.

[0081] As described above, the valve device 1 of this embodiment includes a housing 10 that defines a fluid passage F therein, a fixed disk 20 that is disposed inside the housing 10 and defines a fluid passage hole 23 through which the fluid flows, and a drive unit 40 that outputs a rotational force. The valve device 1 further includes a shaft 50 that rotates about a shaft axis CL, and a drive disk 30 that increases or decreases the opening degree of the fluid passage hole 23 as the shaft 50 rotates, sliding against the fixed disk 20 and rotating about the shaft axis CL. The fixed disk 20 has a seal surface 21 facing the drive disk 30 on the upward direction DRa2 side. The drive disk 30 has a sliding surface 31 that slides against the seal surface 21 on the downward direction DRa1 side. The fixed disk 20 has a convex shape in which the central portion of the seal surface 21 protrudes toward the sliding surface 31 compared to the remaining portions.

[0082] This reduces the frictional force that occurs in the portions of the seal surface 21 and the sliding surface 31 that are spaced apart in the radial direction DRr from their respective centers, which tends to increase if the central portions of both the seal surface 21 and the sliding surface 31 do not protrude toward the other surface. Therefore, the maximum value of the rotational force that can be output by the drive unit 40 can be reduced compared to when the central portions of both the seal surface 21 and the sliding surface 31 do not protrude toward the other surface.

[0083] Furthermore, according to the above embodiment, the following effects can be obtained.

[0084] (1) In the above embodiment, the fixed disk 20 has a surface treatment in which the sealing surface 21 is covered with the coating material 25, so that the central portion of the sealing surface 21 is formed into a convex shape that protrudes toward the sliding surface 31.

[0085] This makes it possible to easily form a slight convex shape of several μm to several tens of μm, compared to a method of forming a convex shape by processing the shape of fixed disk 20, for example.

[0086] (2) In the above embodiment, the coating material 25 has a smaller Young's modulus than the fixed disk 20 .

[0087] According to this, the sealing surface 21 is subjected to a surface treatment in which it is covered with the coating material 25, and when an internal stress is generated in the fixed disk 20 to deform the fixed disk 20, the fixed disk 20 becomes more easily deformed.

[0088] (3) In the above embodiment, the compression spring 90 is provided to bias the drive disk 30 against the fixed disk 20 .

[0089] This makes it easier to maintain the sliding surface 31 of the drive disk 30 in contact with the seal surface 21 of the fixed disk 20 .

[0090] (4) In the above embodiment, the valve device 1 includes the lever 60 that is fixed to the drive disc 30 and couples the drive disc 30 and the shaft 50 so that they can rotate together. The drive disc 30 has a press-fit groove 33 into which the lever 60 is press-fitted, located at a portion spaced apart from the shaft axis CL in the radial direction DRr. The compression spring 90 biases the drive disc 30 toward the fixed disc 20 via the lever 60. The lever 60 transmits the force biased by the compression spring 90 to the press-fit groove 33 in the drive disc 30.

[0091] With this, when the sliding surface 31 of the drive disk 30 presses against the seal surface 21 of the fixed disk 20, the biasing force of the compression spring 90 is transmitted not only to the central portion of the seal surface 21 but also to a portion close to the outer circumferential surface. This makes it easier for the shape of the sliding surface 31 to follow the shape of the seal surface 21. This in turn makes it easier to maintain the contact state between the seal surface 21 and the sliding surface 31.

[0092] Other Embodiments Although typical embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be modified in various ways, for example, as follows.

[0093] In the above embodiment, an example was described in which a surface treatment was used to generate internal stress in the fixed disk 20, causing the fixed disk 20 to have a warped shape. In contrast, an example was described in which the drive disk 30 was not surface-treated to cause the drive disk 30 to have a warped shape, and the sliding surface 31 was approximately parallel to the radial direction DRr before being placed in the valve device 1. However, the shapes of the fixed disk 20 and the drive disk 30 are not limited to this. Modified shapes of the fixed disk 20 and the drive disk 30 will be described with reference to FIGS. 12 to 16. Note that the diagrams shown in FIGS. 12 to 16 show the shapes of the fixed disk 20 and the drive disk 30 before being placed in the valve device 1, in a state in which they are not pressed by the compression spring 90.

[0094] 11 , the drive disk 30 may be formed in a shape that is warped in the same direction as the warping direction of the fixed disk 20. That is, the sliding surface 31 of the drive disk 30 that faces the seal surface 21 may not be flat along the radial direction DRr, but may be formed to be recessed in the direction in which the seal surface 21 protrudes. In this case, the drive disk 30 may be formed in a warped shape by applying a surface treatment similar to that applied to the seal surface 21 of the fixed disk 20 to the surface opposite to the sliding surface 31.

[0095] 12 , the fixed disk 20 may be formed into a shape other than a warped shape. For example, the fixed disk 20 may have a shape in which the central portion of the seal surface 21 protrudes toward the sliding surface 31, and the support surface 22 may be formed into a flat shape along the radial direction DRr. In this case, the fixed disk 20 may be formed into a shape in which the central portion of the seal surface 21 protrudes toward the sliding surface 31 without subjecting the seal surface 21 to surface treatment.

[0096] 13 , the drive disk 30 may be formed in a warped shape such that the sliding surface 31 protrudes toward the sealing surface 21. In this case, the drive disk 30 may be formed so that the central portion of the sliding surface 31 is warped by subjecting the sliding surface 31 to a surface treatment similar to that applied to the sealing surface 21 of the fixed disk 20.

[0097] 14 and 15 , the fixed disk 20 may have the seal surface 21 protruding toward the sliding surface 31 and the support surface 22 formed in a flat shape along the radial direction DRr. In this case, the drive disk 30 may have a warped shape such that the sliding surface 31 protrudes toward the seal surface 21, as shown in Fig. 14 . Alternatively, the drive disk 30 may have the sliding surface 31 protruding toward the seal surface 21 and the side opposite to the sliding surface 31 formed in a flat shape along the radial direction DRr, as shown in Fig. 15 .

[0098] 16, the fixed disk 20 may be formed in a warped shape so that the seal surface 21 protrudes toward the sliding surface 31. In this case, the drive disk 30 may be formed so that the sliding surface 31 protrudes toward the seal surface 21, and the side opposite to the sliding surface 31 may be formed in a flat shape along the radial direction DRr.

[0099] In the above embodiment, an example has been described in which the valve device 1 includes the lever 60 that couples the drive disc 30 and the shaft 50 so that they can rotate together, but this is not limiting. For example, the valve device 1 may not include the lever 60, and the compression spring 90 may directly press the drive disc 30.

[0100] In the above-described embodiment, the valve device 1 has been described as being used in a fluid circulation system mounted on, for example, an electric vehicle or a hybrid vehicle, but is not limited thereto. For example, the valve device 1 may be used in a fluid circulation system mounted on a vehicle other than an electric vehicle or a hybrid vehicle. Furthermore, the valve device 1 may be used for purposes other than vehicles.

[0101] In the above embodiment, the fluid flowing through the fluid passage F in the housing 10 of the valve device 1 is described as coolant, but this is not limiting. For example, the fluid may be a liquid or gas other than coolant.

[0102] In the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential unless they are specifically stated as essential or are clearly considered essential in principle.

[0103] In the above-described embodiments, when numerical values ​​such as the number, values, amounts, ranges, etc. of components of the embodiments are mentioned, they are not limited to the specific numbers unless they are expressly stated as being essential or are clearly limited to a specific number in principle.

[0104] In the above-described embodiments, when referring to the shapes, positional relationships, etc. of components, etc., the shapes, positional relationships, etc. are not limited to those unless otherwise specified or when they are limited in principle to specific shapes, positional relationships, etc.

Claims

1. A valve device comprising: a housing (10) forming a fluid passage (F) therein for circulating a fluid; a fixed disk (20) arranged inside the housing and having at least one flow path hole (23) formed therein through which the fluid flows; a drive unit (40) for outputting a rotational force; a shaft (50) that rotates about a shaft axis (CL) by the rotational force output by the drive unit; and a drive disk (30) that increases or decreases the opening of the flow path hole as the shaft rotates and slides on the fixed disk to rotate about the shaft axis, wherein the fixed disk has a seal surface (21) facing the drive disk on one side in the direction in which the shaft axis extends, and the drive disk has a sliding surface (31) sliding on the seal surface on the other side in the direction in which the shaft axis extends, and wherein the fixed disk and the drive disk have a convex shape formed so that a central portion of at least one of the seal surfaces and the sliding surfaces protrudes toward the other surface compared to the other portion.

2. The valve device according to claim 1, wherein the convex shape of the fixed disk and the drive disk is formed by surface treatment in which at least one of the sealing surface and the sliding surface is covered with a coating material.

3. The valve device according to claim 2, wherein the coating material has a Young's modulus smaller than those of the fixed disk and the driving disk.

4. A valve device according to any one of claims 1 to 3, further comprising a biasing portion (90) for biasing the driving disc against the fixed disc.

5. A valve device as described in claim 4, further comprising a lever (60) fixed to the drive disk and connecting the drive disk and the shaft so that they can rotate together, wherein the drive disk has a connecting portion (33) to which the lever is connected at a portion radially away from the shaft axis when the radial direction is defined as a direction extending radially from the shaft axis, the biasing portion biases the drive disk against the fixed disk via the lever, and the lever transmits the force applied by the biasing portion to the connecting portion on the drive disk.

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