JP7791699B2 - Control valve - Google Patents

Description

The present invention relates to a control valve.

In cooling systems that use coolant to cool the engine, control valves are provided at the branching points to each flow path (such as the radiator flow path) to control the flow of coolant to each flow path.

The control valve includes a casing having a cooling water outlet formed therein, a rotor having a communication port that can communicate with the outlet and rotatably housed within the casing, and a sliding ring that is disposed within the outlet and slides on the outer peripheral surface of the rotor (see, for example, Patent Document 1 below).
With this configuration, by rotating the rotor, communication between the outlet and the communication port through the sliding ring is switched between on and off. When the communication port and the outlet are connected, the coolant flowing through the rotor flows out of the control valve through the communication port, the sliding ring, and the outlet. This distributes the coolant to one or more flow paths in response to the rotation of the rotor.

Japanese Patent Application Laid-Open No. 2016-114125

In order to warm up the engine quickly, it is preferable to maintain a zero-flow state within the cooling system from the time the engine starts until warm-up is complete. A zero-flow state is a state in which coolant is stagnant at least within the engine flow path (a state in which no coolant flows into the radiator flow path, or the flow of coolant within the radiator flow path is low). Therefore, to achieve quick warm-up, it is necessary to improve the sealing performance between the rotor and the sliding ring.

However, if the surface roughness of the rotor is reduced to improve the adhesion between the sliding ring and rotor in order to ensure sealing, the sliding resistance generated between the rotor and sliding ring when the rotor is rotated increases. As a result, the torque required to rotate the rotor (rated torque) increases, leading to larger actuators and increased power consumption.

In light of the above circumstances, the present invention aims to provide a control valve that achieves both improved sealing between the rotor and sliding ring and ensures sliding between the rotor and sliding ring.

In order to solve the above problems, the present invention employs the following aspects.
A control valve according to one aspect of the present invention comprises a casing in which a liquid is contained and in which an outlet for the liquid is formed, a rotor rotatably contained within the casing and in which a communication port that can communicate with the outlet is formed, and a sliding ring having a sliding surface that slides on the outer surface of the rotor when positioned within the outlet, and connecting the outlet and the communication port depending on the rotational position of the rotor, wherein a liquid holding portion is provided on the outer surface of the rotor to hold the liquid between the sliding surface, and the liquid holding portion has a recess for containing the liquid.

In the above-described configuration, the liquid retaining portion that retains liquid between the outer peripheral surface of the valve cylinder and the sliding surface of the sliding ring is provided.
With this configuration, liquid that enters the minute gap between the outer surface of the rotor and the sliding surface of the sliding ring is contained within the recess. This facilitates the formation of a liquid film between the outer surface of the rotor and the sliding surface of the sliding ring due to the influence of surface tension and other factors acting between the liquid retaining portion and the sliding surface. As a result, the liquid film can seal the gap between the rotor and the sliding ring. This makes it difficult for liquid to leak into the inside of the sliding ring through the gap between the rotor and the sliding ring. Therefore, with the above configuration, it becomes easier to maintain a zero-flow state in the cooling system, enabling the vehicle to warm up quickly.

Furthermore, with the above configuration, the liquid film formed between the rotor and sliding ring reduces the area of direct contact between the rotor and sliding ring. This, in turn, reduces the adhesion between the rotor and sliding ring due to the recess in the liquid holding portion. This reduces the sliding resistance during rotor rotation, thereby reducing rotational torque. This helps prevent the actuator from becoming larger and its power consumption from increasing.

Therefore, with the above configuration, it is possible to provide a control valve that achieves both improved sealing performance between the rotor and the sliding ring and ensures sliding performance between the rotor and the sliding ring.
Furthermore, in the above configuration, since the recesses are machined on the outer surface of the rotor to ensure sealing and sliding properties, durability can be improved compared to conventional configurations in which a sliding coating is formed on the outer peripheral surface of the rotor, and therefore sealing and sliding properties can be ensured over a long period of time.

In the control valve of the above aspect, the recess may extend circumferentially around the rotational axis of the rotor.

In the above configuration, because the recesses extend in the direction of rotation of the rotor, as the rotor rotates, the peaks located between adjacent recesses on the outer surface of the rotor move in the direction of rotation of the rotor. In other words, at any position on the sliding surface of the sliding ring, it is possible to prevent the recesses and the peaks located between two recesses from passing alternately as the rotor rotates. This prevents abnormal wear on the sliding surface of the sliding ring.

In the control valve of the above aspect, the rotor may be formed in a cylindrical shape extending coaxially with the rotation axis, and the outer peripheral surface of the rotor may be formed with a groove that extends spirally in the axial direction along the rotation axis as it extends to one side in the circumferential direction, and the groove may be configured such that, when viewed in cross section along the axial direction, multiple recesses are lined up in the axial direction.

In the above configuration, the recess is formed by a groove that extends spirally in the axial direction along the rotation axis on the outer circumferential surface of the rotor as it extends to one side in the circumferential direction.
According to this configuration, recesses can be easily formed on the outer surface of the rotor by lathe machining or the like on the rotor after injection molding. In particular, with the above configuration, machining can be completed while the outer surface of the rotor remains rougher than in the past, which shortens the cutting time compared to when the surface roughness of the outer surface of the rotor is reduced to improve sealing performance. As a result, manufacturing efficiency can be improved and manufacturing costs can be reduced.

In the control valve of the above aspect, if the surface roughness of the outer surface is defined as the rotor surface roughness and the surface roughness of the sliding surface is defined as the ring surface roughness, the rotor surface roughness may be greater than the ring surface roughness.

In the above configuration, by making the rotor surface roughness greater than the ring surface roughness, the liquid can be more reliably held in the liquid holding portion.

In the control valve of the above aspect, the rotor surface roughness may be in the range of 11 μm < X ≦ 45 μm in ten-point average roughness Rz.

The rotor surface roughness is in the range of 11 μm<X≦45 μm in ten-point average roughness Rz, so that both sealing performance and torque reduction can be achieved.
Specifically, since the rotor surface roughness is greater than the lower limit, the sliding resistance acting between the rotor and the sliding ring can be reduced, thereby reducing the rotational torque. Also, since the rotor surface roughness is equal to or less than the upper limit, the sealing performance between the rotor and the sliding ring can be ensured, particularly in the zero flow state (until the warm-up is complete).

The present invention provides a control valve that achieves both improved sealing between the rotor and sliding ring and reduced wear between the rotor and sliding ring.

FIG. 1 is a block diagram of a cooling system according to an embodiment. FIG. 2 is a perspective view of a control valve according to an embodiment. FIG. 2 is an exploded perspective view of the control valve according to the embodiment. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2. FIG. 3 is an enlarged view taken along line VV in FIG. 2. FIG. 6 is an enlarged cross-sectional view taken along line VI-VI in FIG. 5. FIG. 2 is a partially enlarged view of a control valve according to the embodiment. 10 is a graph showing the changes in "leakage amount" and "rotational torque" when the rotor surface roughness is changed.

Next, an embodiment of the present invention will be described with reference to the drawings. The following description will focus on a case in which the control valve of this embodiment is used in a cooling system that uses coolant to cool an engine.

[Cooling System 1]
FIG. 1 is a block diagram of a cooling system 1 .
1, the cooling system 1 is mounted on a vehicle having at least an engine as a vehicle drive source. The vehicle may be a vehicle having only an engine, a hybrid vehicle, a plug-in hybrid vehicle, or the like.

The cooling system 1 is composed of an engine 2 (ENG), a water pump 3 (W/P), a radiator 4 (RAD), a heat exchanger 5 (H/EX), a heater core 6 (HTR), an EGR cooler 7 (EGR), and a control valve 8 (EWV), which are connected by flow paths 10 to 14.
The water pump 3, engine 2, and control valve 8 are connected in this order from upstream to downstream on a main flow path 10. In the main flow path 10, the operation of the water pump 3 causes the coolant to pass through the engine 2 and control valve 8 in this order.

The main flow path 10 is connected to a radiator flow path 11, a warm-up flow path 12, an air conditioning flow path 13, and an EGR flow path 14. The radiator flow path 11, the warm-up flow path 12, the air conditioning flow path 13, and the EGR flow path 14 connect the upstream portion of the main flow path 10 from the water pump 3 to the control valve 8.

The radiator 4 is connected to the radiator flow path 11. In the radiator flow path 11, heat exchange occurs between the coolant and the outside air in the radiator 4.
A heat exchanger 5 is connected to the warm-up flow path 12. Engine oil circulates between the heat exchanger 5 and the engine 2 through an oil flow path 18. In the warm-up flow path 12, heat exchange occurs between the coolant and the engine oil in the heat exchanger 5. That is, when the water temperature is higher than the oil temperature, the heat exchanger 5 functions as an oil warmer and heats the engine oil. On the other hand, when the water temperature is lower than the oil temperature, the heat exchanger 5 functions as an oil cooler and cools the engine oil.

A heater core 6 is connected to the air conditioning flow path 13. The heater core 6 is provided, for example, in a duct (not shown) of an air conditioner. In the air conditioning flow path 13, heat exchange occurs in the heater core 6 between the coolant and the conditioned air flowing through the duct.
The EGR cooler 7 is connected to the EGR passage 14. In the EGR passage 14, the EGR cooler 7 performs heat exchange between the cooling water and the EGR gas.

In the cooling system 1 described above, the coolant that passes through the engine 2 in the main flow path 10 flows into the control valve 8 and is then selectively distributed to each of the flow paths 11-13 by the operation of the control valve 8.

<Control valve 8>
Fig. 2 is a perspective view of the control valve 8. Fig. 3 is an exploded perspective view of the control valve 8. As shown in Figs. 2 and 3, the control valve 8 includes a casing 21, a rotor 22 (see Fig. 3), and a drive unit 23.

(Casing 21)
The casing 21 has a cylindrical casing main body 25 with a bottom and a lid 26 that closes an opening of the casing main body 25. In the following description, the direction along the axis O1 of the casing 21 will be simply referred to as the case axial direction. In the case axial direction, the direction toward the bottom wall 32 of the casing main body 25 with respect to the peripheral wall 31 of the casing main body 25 will be referred to as the first side, and the direction toward the lid 26 with respect to the peripheral wall 31 of the casing main body 25 will be referred to as the second side. Furthermore, the direction perpendicular to the axis O1 will be referred to as the case radial direction, and the direction around the axis O1 will be referred to as the case circumferential direction.

A number of mounting pieces 33 are formed on the peripheral wall 31 of the casing body 25. Each mounting piece 33 protrudes radially outward from the peripheral wall 31. The control valve 8 is fixed, for example, to the engine compartment via each mounting piece 33. The position and number of each mounting piece 33 can be changed as needed.

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.
3 and 4, an inlet port 37 that bulges outward in the case radial direction is formed in a portion of the peripheral wall 31 that is located on the second side in the case axial direction. The inlet port 37 is formed with an inlet 37a (see FIG. 4) that penetrates the inlet port 37 in the case radial direction. The inlet 37a communicates with the inside and outside of the casing 21. The main flow path 10 (see FIG. 1) is connected to the open end face of the inlet port 37 (the outer end face in the case radial direction).

As shown in FIG. 4 , a radiator port 41 that bulges outward in the case radial direction is formed in the peripheral wall portion 31 at a position facing the inlet port 37 in the case radial direction across the axis O1. The radiator port 41 has a fail opening 41a and a radiator outlet 41b formed side by side in the case axial direction. The fail opening 41a and the radiator outlet 41b each penetrate the radiator port 41 in the case radial direction. In this embodiment, the fail opening 41a faces the inlet 37a in the case radial direction. The radiator outlet 41b is located on the first side in the case axial direction relative to the fail opening 41a.

A radiator joint 42 is connected to the open end face (the outer end face in the case radial direction) of the radiator port 41. The radiator joint 42 connects the radiator port 41 to the upstream end of the radiator flow path 11 (see Figure 1). The radiator joint 42 is welded (for example, by vibration welding) to the open end face of the radiator port 41.

A thermostat 45 is provided in the fail-safe opening 41a. That is, the thermostat 45 faces the inlet 37a in the case radial direction. The thermostat 45 opens and closes the fail-safe opening 41a depending on the temperature of the cooling water flowing through the casing 21.

An EGR joint 52 is formed on the opening edge of the EGR outlet 51 in the lid body 26. The EGR joint 52 is formed in a tubular shape extending radially outward in the case toward the second side in the case axial direction, and connects the EGR outlet 51 to the upstream end of the EGR flow path 14 (see FIG. 1). In this embodiment, the EGR joint 52 is formed integrally with the lid body 26. However, the EGR joint 52 may also be formed separately from the lid body 26. The EGR outlet 51 and the EGR joint 52 may also be provided on the peripheral wall portion 31, etc.

As shown in FIG. 3, a warm-up port 56 that bulges outward in the case radial direction is formed in the peripheral wall portion 31 at a portion located on the first side in the case axial direction relative to the radiator port 41. The warm-up port 56 has a warm-up outlet 56a that penetrates the warm-up port 56 in the case radial direction. A warm-up joint 62 is connected to the open end face of the warm-up port 56. The warm-up joint 62 connects the warm-up port 56 to the upstream end of the warm-up flow path 12 (see FIG. 1). The warm-up joint 62 is welded (e.g., by vibration welding) to the open end face of the warm-up port 56.

As shown in FIG. 2, an air conditioning port 66 is formed in the peripheral wall portion 31, between the radiator port 41 and the warm-up port 56 in the case axial direction, and at a position offset approximately 180° in the case circumferential direction from the warm-up port 56. The air conditioning port 66 is formed with an air conditioning outlet 66a that penetrates the air conditioning port 66 in the case radial direction. An air conditioning joint 68 is connected to the open end face of the air conditioning port 66. The air conditioning joint 68 connects the air conditioning port 66 to the upstream end of the air conditioning flow path 13 (see FIG. 1). The air conditioning joint 68 is welded (for example, by vibration welding) to the open end face of the air conditioning port 66.

(Drive unit 23)
2, the drive unit 23 is attached to the bottom wall 32 of the casing body 25. The drive unit 23 is configured to house a motor, a reduction mechanism, a control board, etc., which are not shown.

(Rotor 22)
3 and 4, the rotor 22 is housed in the casing 21. The rotor 22 is formed in a cylindrical shape and disposed coaxially with the axis O1 of the casing 21. The rotor 22 rotates about the axis O1 to open and close each outlet (the radiator outlet 41b, the warm-up outlet 56a, and the air conditioning outlet 66a).

As shown in FIG. 4, the rotor 22 is configured by insert-molding an inner shaft portion 73 inside a rotor body 72 .
The inner shaft portion 73 is formed of a material (e.g., a metal material) that is more rigid than the rotor body 72 (e.g., a resin material). The inner shaft portion 73 extends coaxially with the axis O1. The rotor 22 may be integrally formed of, for example, a resin material, a metal material, or the like.

The first side end of the inner shaft portion 73 penetrates the bottom wall portion 32 in the case axial direction through a through hole 32a formed in the bottom wall portion 32. The first side end of the inner shaft portion 73 is rotatably supported by a first bushing 78 provided on the bottom wall portion 32. Specifically, a first shaft housing wall 79 is formed on the bottom wall portion 32 toward the second side in the case axial direction. The first shaft housing wall 79 surrounds the above-mentioned through hole 32a. The first bushing 78 is fitted inside the first shaft housing wall 79.

A portion of the inner shaft portion 73 that is located on the first side in the case axial direction relative to the first bushing 78 is connected to the drive unit 23 at a portion that is located outside the bottom wall portion 32. This allows the power of the drive unit 23 to be transmitted to the inner shaft portion 73.
A second side end of the inner shaft portion 73 is rotatably supported by a second bushing 84 provided in the cover body 26. Specifically, a second shaft housing wall 86 is formed in the cover body 26 toward the first side in the case axial direction. The second shaft housing wall 86 surrounds the axis O1 on a side radially inward of the EGR outlet 51. The second bushing 84 is fitted inside the second shaft housing wall 86.

The rotor body 72 surrounds the inner shaft portion 73. The rotor body 72 has an outer shaft portion 81 connected to the inner shaft portion 73, a valve cylinder portion 82 surrounding the outer shaft portion 81, and spoke portions 83 connecting the outer shaft portion 81 and the valve cylinder portion 82. The rotor body 72 is preferably formed primarily from a resin selected from the group consisting of PPS (polyphenylene sulfide), PEEK (aromatic polyether ketone), and PA (polyamide).

The outer shaft portion 81 surrounds the entire periphery of the inner shaft portion 73, leaving both ends of the inner shaft portion 73 in the case axial direction exposed. In this embodiment, the outer shaft portion 81 and the inner shaft portion 73 form the rotating shaft 85 of the rotor 22.

A first lip seal 87 is provided within the first shaft housing wall 79 in a portion located on the second side in the case axial direction relative to the first bushing 78. The first lip seal 87 seals between the inner circumferential surface of the first shaft housing wall 79 and the outer circumferential surface of the rotating shaft 85 (outer shaft portion 81).

Meanwhile, a second lip seal 88 is provided within the second shaft housing wall 86, in a portion located on the first side in the case axial direction relative to the second bushing 84. The second lip seal 88 seals between the inner circumferential surface of the second shaft housing wall 86 and the outer circumferential surface of the rotating shaft 85 (outer shaft portion 81).

The valve cylinder portion 82 is arranged coaxially with the axis O1. The valve cylinder portion 82 is arranged in a portion of the casing 21 that is located on the first side of the inlet 37a in the case axial direction. Specifically, the valve cylinder portion 82 is arranged in a position that avoids the fail opening 41a in the case axial direction and straddles the radiator outlet 41b, warm-up outlet 56a, and air conditioning outlet 66a. The inside of the valve cylinder portion 82 forms a flow passage 91 through which coolant that flows into the casing 21 through the inlet 37a flows in the case axial direction. Meanwhile, the portion of the casing 21 that is located on the second side of the valve cylinder portion 82 in the case axial direction forms a connecting flow passage 92 that communicates with the flow passage 91.

A radiator communication port 95 that penetrates the valve cylinder portion 82 in the case radial direction is formed in the valve cylinder portion 82 at the same position in the case axial direction as the above-mentioned radiator outlet 41b. When the radiator communication port 95 at least partially overlaps with the sliding ring 131 inserted into the radiator outlet 41b as viewed in the case radial direction, the radiator communication port 95 connects the radiator outlet 41b to the inside of the flow passage 91.

A warm-up communication port 96 that penetrates the valve cylinder portion 82 in the case radial direction is formed in the valve cylinder portion 82 at the same position in the case axial direction as the warm-up outlet 56a described above. When the warm-up communication port 96 at least partially overlaps with the sliding ring 131 inserted into the warm-up outlet 56a as viewed from the case radial direction, the warm-up communication port 96 communicates between the warm-up outlet 56a and the inside of the flow passage 91.

An air conditioning communication port 97 that penetrates the valve cylinder portion 82 in the case radial direction is formed in the valve cylinder portion 82 at the same position in the case axial direction as the above-mentioned air conditioning outlet 66a. When the air conditioning communication port 97 at least partially overlaps with the sliding ring 131 inserted into the air conditioning outlet 66a as viewed from the case radial direction, the air conditioning communication port 97 connects the air conditioning outlet 66a to the inside of the circulation passage 91.

As the rotor 22 rotates around the axis O1, it switches between communication and blocking between the inside of the flow passage 91 and each of the outlets 41b, 56a, and 66a. The communication pattern between the outlets and the communication ports can be set as appropriate. The layout of the outlets and communication ports can be switched according to the set communication pattern. Corresponding outlets and communication ports need only be positioned so that at least a portion of them overlap in the case axial direction.

Next, we will explain in detail the connection between the warm-up port 56 and the warm-up joint 62. The connection between the radiator port 41 and the radiator joint 42, and the connection between the air conditioning port 66 and the air conditioning joint 68 have the same configuration as the connection between the warm-up port 56 and the warm-up joint 62, so we will not explain them here.

Figure 5 is an enlarged cross-sectional view corresponding to line V-V in Figure 2. In the following description, the direction along the axis O2 of the warm-up outlet 56a may be referred to as the port axis direction. In this case, in the port axis direction, the direction toward the axis O1 of the warm-up port 56 is referred to as the inward direction, and the direction away from the axis O1 of the warm-up port 56 is referred to as the outward direction. In addition, the direction perpendicular to the axis O2 may be referred to as the port radial direction, and the direction around the axis O2 may be referred to as the port circumferential direction.

As shown in Figure 5, the warm-up port 56 has a cylindrical seal portion 101 extending in the port axial direction and a port flange portion 102 extending radially outward from the cylindrical seal portion 101. The inside of the cylindrical seal portion 101 forms the warm-up outlet 56a described above.

The warm-up joint 62 has a joint tubular portion 110 arranged coaxially with the axis O2, and a joint flange portion 111 that extends outward in the port radial direction from the inner end of the joint tubular portion 110 in the port axial direction.

The joint flange portion 111 is formed in an annular shape with an outer diameter equal to that of the port flange portion 102 and an inner diameter larger than the outer diameter of the tubular seal portion 101. The joint flange portion 111 is joined to the port flange portion 102 by vibration welding or the like.

In this embodiment, a sealing mechanism 130 is provided in the area surrounded by the warm-up port 56 and the warm-up joint 62. The sealing mechanism 130 includes a sliding ring 131, a biasing member 132, a seal ring 133, and a holder 134. As shown in FIG. 3, sealing mechanisms 130 having the same configuration as the sealing mechanism 130 provided in the warm-up port 56 are also provided in the radiator port 41 and the air conditioning port 66 described above. In this embodiment, the sealing mechanisms 130 provided in the radiator port 41 and the air conditioning port 66 are denoted by the same reference numerals as the sealing mechanism 130 provided in the warm-up port 56, and their description will be omitted.

As shown in Figure 5, the sliding ring 131 is inserted into the warm-up outlet 56a. The sliding ring 131 extends coaxially with the axis O2 and is formed in a multi-stage cylindrical shape with an outer diameter that gradually decreases as it extends outward in the port axial direction. Specifically, it has a large diameter portion 141 located on the inside in the port axial direction, and a small diameter portion 142 that continues from the large diameter portion 141 to the outside in the port axial direction.

The outer peripheral surface of the large diameter portion 141 is configured to be able to slide against the inner peripheral surface of the cylindrical seal portion 101. In other words, the movement of the large diameter portion 141 in the port radial direction relative to the warm-up port 56 is restricted by the cylindrical seal portion 101. The inner end surface of the large diameter portion 141 in the port axial direction forms a sliding surface 141a that slides against the outer peripheral surface of the cylindrical valve portion 82. In this embodiment, the sliding surface 141a is a curved surface formed to match the radius of curvature of the cylindrical valve portion 82.

The outer peripheral surface of the small diameter portion 142 is continuous with the outer peripheral surface of the large diameter portion 141 via a stepped surface 143. The stepped surface 143 slopes outward in the port radial direction as it extends inward in the port axial direction, and then extends further outward in the port radial direction. Therefore, a seal gap Q is provided in the port radial direction between the outer peripheral surface of the small diameter portion 142 and the inner peripheral surface of the cylindrical seal portion 101.
On the other hand, the inner peripheral surface of the small diameter portion 142 smoothly connects to the inner peripheral surface of the large diameter portion 141. The outer end surface of the small diameter portion 142 in the port axial direction (hereinafter referred to as the "seat surface 142a") is formed as a flat surface perpendicular to the port axial direction. The seat surface 142a of the small diameter portion 142 is located at the same position in the port axial direction as the outer end surface of the cylindrical seal portion 101. The sliding ring 131 is spaced apart from the warm-up joint 62 in both the port radial direction and the port axial direction.

The biasing member 132 is disposed between the seat surface 142a of the sliding ring 131 and the warm-up joint 62. The biasing member 132 is, for example, a wave spring. The biasing member 132 biases the sliding ring 131 inward in the port axial direction (toward the valve cylinder portion 82).

The seal ring 133 is, for example, a Y-shaped packing. The seal ring 133 surrounds the sliding ring 131 (small diameter portion 142) with its opening (forked portion) facing inward in the port axis direction. Specifically, when the seal ring 133 is positioned within the above-mentioned seal gap Q, the tips of the forked portions are slidably in close contact with the outer circumferential surface of the small diameter portion 142 and the inner circumferential surface of the tubular seal portion 101, respectively. Within the seal gap Q, the hydraulic pressure of the casing 21 is introduced to the inner region of the seal ring 133 in the port axis direction through the gap between the inner circumferential surface of the tubular seal portion 101 and the sliding ring 131. In this case, the stepped surface 143 faces the sliding surface 141a on the sliding ring 131 in the port axis direction and constitutes a pressure-receiving surface that is pressed inward in the port axis direction by the hydraulic pressure of the cooling water in the casing 21.

The holder 134 is configured to be movable in the port axial direction relative to the warm-up port 56 and warm-up joint 62 within the seal gap Q. The holder 134 has a holder tubular portion 151 and a holder flange portion 152.

The holder cylindrical portion 151 extends in the port axial direction and is inserted into the seal gap Q from the outside in the port axial direction. The bottom of the seal ring 133 abuts against the holder cylindrical portion 151, thereby restricting the seal ring 133 from moving outward in the port axial direction.
The holder cylindrical portion 151 surrounds the small diameter portion 142 and the urging member 132 while straddling the small diameter portion 142 and the urging member 132 in the port axial direction.

The holder flange portion 152 protrudes outward in the port radial direction from the outer end of the holder tubular portion 151 in the port axial direction. The holder flange portion 152 is disposed between the seal tubular portion 101 and the joint tubular portion 110.

In the sliding ring 131, the area S1 of the step surface 143 and the area S2 of the sliding surface 141a are set to satisfy the following expressions (1) and (2).
S1<S2≦S1/k...(1)
α≦k<1 ... (2)
k: pressure reduction constant of the cooling water flowing through the minute gap between the sliding surface 141a and the valve cylinder portion 82; α: lower limit of the pressure reduction constant determined by the physical properties of the cooling water. Note that the area S1 of the step surface 143 and the area S2 of the sliding surface 141a refer to the areas when projected in the port axial direction.

In equation (2), α is a standard value of the pressure reduction constant that is determined by the type of cooling water, the operating environment (e.g., temperature), etc. For example, under normal operating conditions, α = 1/2 for water. If the physical properties of the cooling water used change, α will change to 1/3, etc.
Furthermore, the pressure reduction constant k in equation (2) is a standard value of α (e.g., ½) when the sliding surface 141a is in uniform contact with the valve cylinder portion 82 from the outer edge to the inner edge in the port radial direction. However, due to manufacturing errors, assembly errors, etc. of the sliding ring 131, the gap between the outer periphery of the sliding surface 141a and the valve cylinder portion 82 may be slightly larger than the gap between the inner periphery of the sliding surface 141a. In this case, the pressure reduction constant k in equation (2) gradually approaches k=1.

In this embodiment, assuming that there is a small gap between the sliding surface 141a of the sliding ring 131 and the outer surface of the valve cylinder portion 82 to allow sliding, the relationship between the areas S1 and S2 of the step surface 143 and the sliding surface 141a is determined by equations (1) and (2).
That is, the pressure of the cooling water in the casing 21 acts directly on the step surface 143 of the sliding ring 131. On the other hand, the pressure of the cooling water in the casing 21 does not act directly on the sliding surface 141a. Specifically, the pressure of the cooling water acts while decreasing as the cooling water flows through the minute gap between the sliding surface 141a and the valve cylinder portion 82 from the outer edge toward the inner edge in the port radial direction. At this time, the pressure of the cooling water gradually decreases toward the inside in the port radial direction, and tends to push the sliding ring 131 outward in the port axial direction.

As a result, a force obtained by multiplying the area S1 of the stepped surface 143 by the pressure P inside the casing 21 acts directly on the stepped surface 143 of the sliding ring 131. On the other hand, a force obtained by multiplying the area S2 of the sliding surface 141a by the pressure P inside the casing 21 and the pressure reduction constant k acts on the sliding surface 141a of the sliding ring 131.

In the control valve 8 of this embodiment, the areas S1 and S2 are set so that k×S2≦S1 holds, as is clear from equation (1). Therefore, the relationship P×k×S2≦P×S1 also holds.
Therefore, the force F1 (F1 = P × S1) acting on the step surface 143 of the sliding ring 131 in the pressing direction is greater than or equal to the force F2 (F2 = P × k × S2) acting on the sliding surface 141 a of the sliding ring 131 in the lifting direction. Therefore, in the control valve 8 of this embodiment, the gap between the sliding ring 131 and the valve cylinder portion 82 can be sealed only by the relationship between the pressures of the cooling water in the casing 21.

In contrast, in this embodiment, as described above, the area S1 of the stepped surface 143 of the sliding ring 131 is smaller than the area S2 of the sliding surface 141a. Therefore, even if the pressure of the cooling water inside the casing 21 increases, the sliding surface 141a of the sliding ring 131 is prevented from being pressed against the valve cylinder portion 82 with excessive force. Therefore, when the control valve 8 of this embodiment is adopted, it is possible to avoid an increase in the size and output of the drive unit 23 that rotates the rotor 22, and to prevent premature wear of the sliding ring 131 and each bushing 78, 84 (see Figure 4).

In this way, in this embodiment, the area S2 of the sliding surface 141a is set larger than the area S1 of the stepped surface 143, as long as the inward pressing force in the port axial direction acting on the sliding ring 131 is not less than the outward lifting force in the port axial direction acting on the sliding ring 131. This prevents the sliding ring 131 from pressing against the valve cylinder portion 82 with excessive force, while also sealing the gap between the sliding ring 131 and the valve cylinder portion 82.

Fig. 6 is an enlarged view of a cross section taken along line VI-VI in Fig. 5. Fig. 7 is a partial enlarged view showing the outer circumferential surface of the rotor 22 (valve cylinder portion 82) included in the control valve 8 according to the embodiment.
As shown in Figures 6 and 7, a liquid holding portion 160 is provided on the outer peripheral surface (outer surface) of the valve cylinder portion 82 of the rotor 22, and holds cooling water between the sliding surface 141a of the sliding ring 131 and the liquid holding portion 160.

The liquid holding portion 160 has a recess 161 that contains the coolant and a liquid interposition portion 162 in which the coolant is interposed. The liquid holding portion 160 only needs to be provided on at least the surface of the outer circumferential surface of the valve cylinder portion 82 that passes through the radiator outlet 41b, warm-up outlet 56a, and air conditioning outlet 66a when the rotor 22 rotates (the overlapping portions as viewed radially from the case).

The recess 161 is recessed radially inward relative to the outer peripheral surface of the valve cylinder portion 82. In this embodiment, the recess 161 is configured as a groove 170 that extends spirally on the outer peripheral surface of the valve cylinder portion 82. The groove 170 is formed by lathe machining or the like on the outer peripheral surface of the valve cylinder portion 82. The groove 170 extends toward one side in the case circumferential direction and then toward a first side in the case axial direction.

The recesses 161 are the portions of the opening of the groove 170 that appear on the same cross section when the valve cylinder portion 82 is cut along the case axis. That is, in a cross section viewed along the case axis, multiple recesses 161 are lined up in the case axis direction. Each recess 161 is formed, for example, in a triangular shape when viewed along the case axis. The dimension of the recess 161 in the case axis direction is sufficiently smaller than that of the sliding surface 141a. The ratio between the dimension in the case axis direction and the dimension in the case radial direction of the recess 161 can be changed as appropriate.

The liquid interposition portion 162 is a portion of the valve cylinder portion 82 located between adjacent recesses 161 in the case axial direction. In this embodiment, the liquid interposition portion 162 constitutes the outer peripheral surface of the valve cylinder portion 82. In the illustrated example, the liquid interposition portion 162 is formed in the shape of a ridge extending along the case circumferential direction, with adjacent recesses 161 lined up with no gaps in the case axial direction. However, the liquid interposition portion 162 may also be formed in a band shape, with adjacent recesses 161 lined up with gaps between them.

If the surface roughness of the liquid holding portion 160 of the outer peripheral surface of the valve cylinder portion 82 is defined as rotor surface roughness _Rz1 and the surface roughness of the sliding surface 141a is defined as ring surface roughness _Rz2 , then the rotor surface roughness _Rz1 is greater than the ring surface roughness _Rz2 ( _Rz1 > _Rz2 ). Because the rotor surface roughness _Rz1 is greater than the ring surface roughness _Rz2 , the sealing performance can be controlled by the rotor surface roughness _Rz1 of the rotor 22.

It is preferable that the rotor 22 (particularly the outer peripheral surface of the valve cylinder portion 82) be harder than the sliding ring 131 (particularly the sliding surface 141a). Generally, when the rotor 22 wears, the sealing performance decreases, but by having this configuration, it is possible to suppress the wear of the rotor 22 and maintain the sealing performance, and it is possible to maintain the roughness of the rotor 22 and keep the torque constant.
It is preferable that the sliding ring 131 does not contain at least CF (fluorocarbon), because if the sliding ring 131 contains CF, the wear of the rotor 22 will be accelerated.

The rotor surface roughness Rz ₁ and the ring surface roughness Rz ₂ are ten-point average roughness Rz standardized in JIS B 0601.
The rotor surface roughness _Rz1 refers to the surface roughness in the axial direction of the case of the outer peripheral surface of the rotor 22, and can be measured, for example, with a surface roughness and contour measuring instrument (model: SV-C3200H8, manufactured by Mitutoyo Corporation). The rotor surface roughness _Rz1 is set to a range of ten-point average roughness Rz(X) greater than 11 μm and equal to or less than 45 μm (11 μm<X≦45 μm).

The ring surface roughness _Rz2 refers to the surface roughness of the sliding surface 141a of the sliding ring 131, and can be measured, for example, with a surface roughness/contour measuring instrument (model: SV-C3200H8, manufactured by Mitutoyo Corporation). Regardless of the value of the rotor surface roughness _Rz1 , the ring surface roughness _Rz2 is preferably set to 6.3 μm or less in ten-point average roughness Rz. It is more preferable that the ring surface roughness _Rz2 be set in the range of greater than 1 μm and less than 5 μm (1 μm < X ≦ 5 μm).

[Operation method of control valve 8]
Next, the operation of the control valve 8 will be described.
<Normal operation>
As shown in Fig. 1, in the main flow path 10, the coolant delivered by the water pump 3 is heat exchanged in the engine 2 and then flows toward the control valve 8. As shown in Fig. 4, the coolant that has passed through the engine 2 in the main flow path 10 flows into the connecting flow path 92 in the casing 21 through the inlet 37a.

A portion of the cooling water that flows into the connecting passage 92 flows into the EGR outlet 51. The cooling water that flows into the EGR outlet 51 passes through the EGR joint 52 and is supplied to the EGR passage 14. The cooling water supplied to the EGR passage 14 undergoes heat exchange between the cooling water and EGR gas in the EGR cooler 7, and is then returned to the main passage 10.

Meanwhile, the cooling water that flows into the connecting flow passage 92 but does not flow into the EGR outlet 51 flows into the flow passage 91 from the second side in the case axial direction. The cooling water that flows into the flow passage 91 is distributed to each outlet as it flows through the flow passage 91 in the case axial direction. In other words, the cooling water that flows into the flow passage 91 is distributed to each of the flow passages 11 to 13 through the outlets that are connected to the communication openings.

To switch the communication pattern between the outlet and the communication port in the control valve 8, the rotor 22 is rotated around the axis O1. Then, by stopping the rotation of the rotor 22 at a position corresponding to the desired communication pattern, the outlet and the communication port are connected in a communication pattern corresponding to the stopping position of the rotor 22.

<Zero flow state>
Next, the operation of the cooling system 1 in a zero-flow state will be described. In the cooling system 1 of this embodiment, the cooling system 1 is maintained in a zero-flow state from the start of engine startup until warm-up is complete. The zero-flow state is a state in which communication between at least the radiator outlet 41b and the radiator communication port 95 is blocked (the opening degree of the radiator outlet 41b is set to 0%), and coolant is stagnant in the radiator flow path 11. In this embodiment, in the zero-flow state, with the water pump 3 driven, only the connection flow path 92 and the EGR outlet 51 are in communication.

In a zero-flow state, the cooling water that flows into the connecting passage 92 flows into the EGR outlet 51. The cooling water that flows into the EGR outlet 51 passes through the EGR joint 52 and is supplied to the EGR passage 14.

On the other hand, in the zero-flow state, the opening degree of all outlets other than the EGR outlet 51 (radiator outlet 41b, warm-up outlet 56a, and air conditioning outlet 66a) is 0%. Therefore, coolant stagnates in the radiator flow path 11, warm-up flow path 12, and air conditioning flow path 13. This reduces the heat exchange efficiency between the heat released from the engine and the coolant in the radiator outlet 41b, enabling early warm-up.

When the temperature of the coolant delivered from the water pump 3 (the temperature of the coolant flowing into the inlet port 37) reaches a predetermined temperature, it can be determined that the engine has warmed up. This causes the cooling system 1 to cancel the zero-flow state and distribute the coolant to each flow path 11-13 as described above, depending on the engine condition and vehicle driving conditions.

In order to achieve early warm-up, it is necessary to improve the sealing performance between the rotor 22 (valve cylinder portion 82) and the sliding ring 131 (sliding surface 141a).

Therefore, in this embodiment, a liquid holding portion 160 is provided on the outer circumferential surface of the valve cylinder portion 82 to hold the cooling water between the valve cylinder portion 82 and the sliding surface 141a.
According to this configuration, cooling water that has entered the minute gap between the outer circumferential surface of the valve cylinder portion 82 and the sliding surface 141a is contained within the recess 161. As a result, a liquid film 163 is easily formed between the outer circumferential surface of the valve cylinder portion 82 and the sliding surface 141a due to the influence of surface tension and the like acting between the liquid holding portion 160 and the sliding surface 141a. As a result, the liquid film 163 can seal the gap between the rotor 22 and the sliding ring 131. This makes it difficult for cooling water to leak into the sliding ring 131 through the gap between the rotor 22 and the sliding ring 131. Therefore, according to the above embodiment, it is easier to maintain a zero-flow state in the cooling system 1, enabling the vehicle to warm up quickly.

In addition, the liquid film 163 formed between the rotor 22 and the sliding ring 131 reduces the area of direct contact between the rotor 22 (valve cylinder portion 82) and the sliding ring 131. As a result, the recess 161 of the liquid holding portion 160 reduces the adhesion between the rotor 22 and the sliding ring 131. This reduces the sliding resistance when the rotor 22 rotates, thereby reducing the rotational torque. This prevents the actuator from becoming larger and increasing power consumption.

Therefore, according to the above embodiment, it is possible to provide a control valve 8 that achieves both improved sealing performance between the rotor 22 and the sliding ring 131 and ensures sliding performance between the rotor 22 and the sliding ring 131.
Furthermore, in this embodiment, sealing and sliding properties can be ensured by processing the recess 161 on the outer peripheral surface of the valve cylinder portion 82, which improves durability compared to, for example, a conventional configuration in which a sliding coating is formed on the outer peripheral surface of the rotor, thereby ensuring sealing and sliding properties over a long period of time.

In the above embodiment, the recesses 161 extend in the rotational direction (circumferential direction of the case) of the rotor 22. As a result, when the rotor 22 rotates, the apex (liquid interposition portion 162) located between adjacent recesses 161 on the outer circumferential surface of the rotor 22 moves in the circumferential direction of the case. In other words, at any position on the sliding surface 141a, the recesses 161 and the liquid interposition portion 162 can be prevented from passing alternately as the rotor 22 rotates. This prevents abnormal wear of the sliding surface 141a.

In the above embodiment, the recess 161 is configured by a groove 170 that extends spirally on the outer peripheral surface of the valve cylinder portion 82, extending toward one side in the case circumferential direction and then toward a first side in the case axial direction.
According to this configuration, by subjecting the injection-molded valve cylinder portion 82 to lathe processing or the like, the recess 161 can be easily formed in the outer peripheral surface of the valve cylinder portion 82. In particular, in this embodiment, since the processing can be completed while the outer peripheral surface of the valve cylinder portion 82 is left rougher than in the past, cutting time can be shortened compared to when the surface roughness of the outer peripheral surface of the valve cylinder portion 82 is reduced to improve sealing performance. As a result, manufacturing efficiency can be improved and manufacturing costs can be reduced.

In the above embodiment, by making the rotor surface roughness Rz ₁ of the rotor 22 larger than the ring surface roughness Rz ₂ , the liquid holder 160 can hold the cooling water more reliably.

In the above embodiment, the rotor surface roughness _Rz1 is in the range of 11<X≦45 in ten-point average roughness Rz, so that it is possible to achieve both sealing performance and torque reduction.
Specifically, because the rotor surface roughness _Rz1 is greater than the above-mentioned lower limit, the sliding resistance acting between the rotor 22 and the sliding ring 131 can be reduced, thereby reducing the rotational torque. Also, because the rotor surface roughness _Rz1 is equal to or less than the above-mentioned upper limit, the sealing performance between the rotor 22 and the sliding ring 131 can be ensured, particularly in the zero flow state (until warm-up is complete).

In the above embodiment, the ring surface roughness _Rz2 is set to 6.3 μm or less in ten-point average roughness Rz.
This configuration makes it possible to improve the sealing performance between the rotor 22 and the sliding ring 131 while suppressing wear between the rotor 22 and the sliding ring 131. In particular, by making the ring surface roughness _Rz2 sufficiently smaller than the rotor surface roughness _Rz1 , it is possible to suppress wear on the outer circumferential surface of the rotor 22. As a result, the rotor surface roughness _Rz1 can be maintained within a desired range for a long period of time, making it easier to ensure sealing performance.

8 is a graph showing the changes in "leakage amount" and "rotational torque" when the rotor surface roughness Rz ₁ at standard pressure is changed. The inventors of the present application conducted a test to verify the effects of the rotor surface roughness Rz ₁ on the sealing performance and sliding performance between the rotor 22 (valve cylinder portion 82) and the sliding ring 131 (sliding surface 141a).
The "rotor surface roughness _Rz1 " on the horizontal axis of the graph is the ten-point average roughness Rz standardized in JIS B 0601, and is a value measured using a surface roughness and contour measuring instrument (model: SV-C3200H8, manufactured by Mitutoyo Corporation). In this test, the ring surface roughness _Rz2 was set to a range that would not affect wear of the rotor 22, for example, 6.3 μm or less.

The "leakage amount" shown on the left vertical axis of the graph is the measured value when the coolant temperature was set to -30°C (low temperature), 25°C (normal temperature), and 80°C (typical warm-up temperature). Measurements were taken using a Memory HiCorder (model: 860-50, manufactured by Hioki E.E. Corporation) and a 16-channel scanner unit (model: 8958, manufactured by Hioki E.E. Corporation).
The "rotational torque" shown on the right vertical axis of the graph is the rotational torque of the rotor 22 at standard pressure, which was measured using a rotational torque meter (model: UTMII-2Nm, manufactured by Unipulse Corporation).
The above-mentioned "standard pressure" is the maximum pressure in a driving test conducted using a driving pattern for measuring fuel efficiency, and indicates the discharge pressure of the cooling water sent out from the water pump 3 (the pressure of the cooling water flowing into the inlet port 37).

The relationship between rotor surface roughness _Rz1 and leakage rate shows that the larger the rotor surface roughness _Rz1 , the greater the leakage rate. In other words, the rougher the surface of the rotor 22, the greater the leakage rate. This is thought to be because a gap is more likely to form between the outer circumferential surface of the valve cylinder portion 82 and the sliding surface 141a. As shown in Figure 8, when the coolant is at 80°C, the viscosity of the coolant decreases, making it easier to flow. When the rotor surface roughness _Rz1 is greater than 45 μm, the leakage rate increases above the specified value C, making it difficult to effectively maintain a zero-flow state.

The relationship between rotor surface roughness _Rz1 and rotational torque shows that the smaller the rotor surface roughness _Rz1 , the greater the rotational torque. This is thought to be because the smoother the surface of the rotor 22, the greater the adhesion between the rotor 22 and the sliding ring 131, resulting in greater friction, and therefore an increase in torque when the rotor 22 rotates. When the rotor surface roughness _Rz1 is 11 μm or less, the torque cannot be suppressed to the desired level, resulting in increased power consumption, etc.

Although the absolute values of the sealing and sliding properties due to differences in rotor surface roughness _Rz1 differ depending on the measured cooling water temperature, the same trends were observed regardless of the measured temperature. That is, as the cooling water temperature decreases, the viscosity of the cooling water increases. Therefore, comparing the various cooling water temperatures (-30°C, 25°C, and 80°C) in the graph shown in Figure 8, the amount of leakage tends to decrease as the cooling water temperature decreases.

Although the absolute values of the sealing and sliding properties due to differences in rotor surface roughness _Rz1 differ depending on the cooling water pressure (the discharge pressure of the water pump 3), similar trends were observed regardless of the measured pressure. That is, as the cooling water pressure increases, the pressure acting between the outer circumferential surface of the valve cylinder portion 82 and the sliding surface 141a increases, tending to increase the leakage amount. Furthermore, as the cooling water pressure increases, the pressing force F1 acting on the stepped surface 143 of the sliding ring 131 increases, increasing the frictional force acting between the outer circumferential surface of the valve cylinder portion 82 and the sliding surface 141a of the sliding ring 131, and therefore increasing the sliding resistance.

Based on the above results, in this embodiment, it is preferable that the rotor surface roughness _Rz1 (X) is in the range of 11 μm<X≦45 μm in ten-point average roughness Rz. When the rotor surface roughness _Rz1 is in this range, it is possible to achieve both improved sealing performance between the rotor 22 and the sliding ring 131 and suppressed wear between the rotor 22 and the sliding ring 131.

In order to effectively improve the sealing performance between the rotor 22 and the sliding ring 131 and suppress wear between the rotor 22 and the sliding ring 131 in various temperature and pressure ranges of the cooling water, the rotor surface roughness _Rz1 (X) is preferably in the range of greater than 25 μm and less than 44 μm (25 μm<X≦44 μm), and more preferably in the range of greater than 25 μm and less than 38 μm (25 μm<X≦38 μm). In particular, by setting the rotor surface roughness _Rz1 to 38 μm or less, the sealing performance is further ensured, cooling water can be supplied only to desired flow paths at desired times, and fuel consumption can be reduced.

In addition, the components in the above-described embodiments may be replaced with well-known components as appropriate without departing from the spirit of the present invention, and various modifications to the above-described embodiments are also included.

In the above-described embodiment, cooling water was used as the liquid, but this is not limited to this. For example, water, a solution, etc. may also be used as the liquid.

In the present embodiment, the recess 161 is configured as a groove 170 that extends spirally on the outer peripheral surface of the valve cylinder portion 82, but this is not limiting. The recess 161 may be configured as a groove that extends linearly in the case circumferential direction on the outer peripheral surface of the valve cylinder portion 82. The recess 161 may be configured as a groove that extends in a wave-like pattern on the outer peripheral surface of the valve cylinder portion 82. The recess 161 may be a discontinuous recess provided on the outer peripheral surface of the valve cylinder portion 82. In other words, the recesses 161 may be arranged in an island-like pattern at intervals in the case axial or circumferential direction.
In the above-described embodiment, the recess 161 is formed by cutting the outer circumferential surface of the valve cylinder portion 82 by lathe processing or the like, but the present invention is not limited to this configuration. The recess 161 may be formed by a method other than cutting, such as sandblasting or etching.

In the above-described embodiment, the recess 161 is described as being formed, for example, in a triangular shape when viewed in cross section along the case axis direction, but this is not limited to this. The recess 161 may also be formed in a semicircular or rectangular shape when viewed in cross section along the case axis direction.

In the above embodiment, the coolant flowing into the control valve 8 is distributed to the radiator flow path 11, the warm-up flow path 12, the air conditioning flow path 13, and the EGR flow path 14. However, the present invention is not limited to this configuration. The control valve 8 may be configured to distribute the coolant flowing into the control valve 8 to at least two flow paths.
Furthermore, the layout, type, shape, etc. of each communication port and outlet port can be changed as appropriate.

In the above-described embodiment, a configuration was described in which the valve cylinder portion 82 of the rotor 22 is open on both sides in the case axial direction, but this configuration is not limited to this. The rotor 22 can be designed in any suitable manner as long as cooling water can enter the valve cylinder portion 82. For example, the rotor 22 may be configured with a closing portion that closes both openings in the valve cylinder portion 82 in the case axial direction. In this case, a communication port or the like may be formed in the closing portion to connect the inside and outside of the rotor 22 in the case axial direction. Even in this case, a liquid holding portion 160 may be provided on the surface of the closing portion that faces the sliding surface 141a (the outer surface of the rotor 22).

In the above-described embodiment, the rotor 22 (valve cylinder portion 82) and the casing 21 (circumferential wall portion 31) are each cylindrical (with a uniform diameter throughout the entire case axial direction), but this configuration is not limited to this. That is, as long as the valve cylinder portion 82 is rotatable within the peripheral wall portion 31, the outer diameter of the valve cylinder portion 82 and the inner diameter of the peripheral wall portion 31 may vary in the case axial direction. In this case, the valve cylinder portion 82 and the peripheral wall portion 31 may be variously shaped, such as spherical (a shape in which the diameter decreases from the center toward both ends in the case axial direction), a shape in which multiple spherical shapes are connected in the case axial direction, a tapered shape (a shape in which the diameter gradually changes from the first side to the second side in the case axial direction), or a stepped shape (a shape in which the diameter gradually changes from the first side to the second side in the case axial direction).

8...control valve 21...casing 22...rotor 85...rotating shaft 131...sliding ring 141a...sliding surface 160...liquid holding portion 161...recess 162...liquid interposing portion

Claims (4)

a casing in which a liquid outlet is formed and in which the liquid is contained;
a rotor rotatably accommodated within the casing and having a communication port formed therein that can communicate with the outlet;
a sliding ring that is disposed within the outlet and has a sliding surface that slides on an outer surface of the rotor, and that connects the outlet and the communication port in accordance with a rotational position of the rotor,
a liquid retaining portion that retains liquid between the outer surface of the rotor and the sliding surface,
the liquid holding portion has a recess for accommodating a liquid,
The recessed portion extends continuously in the circumferential direction around the rotation axis of the rotor around the entire outer surface of the rotor . The rotor is formed in a cylindrical shape extending coaxially with the rotation axis,
a groove is formed on the outer peripheral surface of the rotor, the groove extending spirally in an axial direction along the rotation axis as it extends toward one side in the circumferential direction;
The control valve according to claim 1 , wherein the groove is configured such that a plurality of the recesses are arranged in the axial direction in a cross section along the axial direction. If the surface roughness of the outer surface is the rotor surface roughness and the surface roughness of the sliding surface is the ring surface roughness, then:
3. The control valve according to claim 1 , wherein the rotor surface roughness is greater than the ring surface roughness. 4. The control valve according to claim 3 , wherein the rotor surface roughness is in the range of 11 μm<X≦45 μm in ten-point average roughness Rz.