Control valve

A control valve includes a valve housing, a joint member, a valve body, and a sealing tube member. A seal ring, which receives a liquid pressure inside the valve housing and comes into tight contact with the joint member and the sealing tube member, is provided between the joint member and the sealing tube member. The sealing tube member has a biasing pressure receiving surface receiving the liquid pressure inside the valve housing in a direction along a direction of the valve body. The seal ring is disposed at a position where the sealing tube member is not pressurized in the direction of the valve body. An area of a valve sliding contact surface is set to be larger than an area of the biasing pressure receiving surface.

TECHNICAL FIELD

The present invention relates to a control valve used for switching or the like of flow channels for vehicle cooling water.

Priority is claimed on Japanese Patent Application No. 2017-053683, filed Mar. 17, 2017, the content of which is incorporated herein by reference.

BACKGROUND ART

In cooling systems for cooling an engine using cooling water, in addition to a radiator flow channel for the cooling water circulating between a radiator and the engine, there are cases where a bypass flow channel, a warming-up flow channel, or the like is additionally installed. The bypass flow channel is a flow channel bypassing the radiator The warming-up flow channel is a flow channel passing through an oil warmer. In a cooling system of this kind, a control valve is interposed in branching portions of the flow channels. In the cooling system, the flow channels are suitably switched using the control valves. A control valve in which a valve body having a cylinder wall is rotatably disposed inside a valve housing is known (for example, refer to Patent Literature 1). The control valve disclosed in Patent Literature 1 opens and closes an arbitrary flow channel In accordance with a rotation position of the valve body

In the control valve disclosed in Patent Literature 1, an inflow port for allowing a liquid such as cooling water to flow in and a set number of discharge ports for discharging a liquid that has flowed into the valve housing to the outside are provided in the valve housing. A plurality of valve holes through which the inside and the outside of the cylinder wall communicate with each other are formed in the cylinder wall of the valve body in a manner corresponding to the discharge ports. A joint member for connecting a piping on the discharge side is joined to a circumferential edge of each of the discharge ports in the valve housing. First end portions of sealing tube members are slidably held inside the valve housing of the joint member. A valve sliding contact surface is provided on a second end portion side. The valve sliding contact surface of each of the sealing tube members comes into sliding contact with an outer surface of the cylinder wall at a position where at least a part of the valve body overlaps a rotation path of the corresponding valve hole.

The valve body allows an outflow of a liquid to the corresponding discharge port from an inner region of the cylinder wall when at a rotation position where the sealing tube member communicates with the corresponding valve hole. The valve body blocks an outflow of a liquid to the corresponding discharge port from the inner region of the cylinder wall when at a rotation position where the sealing tube member does not communicate with the corresponding valve hole. The rotation position of the valve body is controlled by an actuator (electric motor).

In the control valve disclosed in Patent Literature 1, the sealing tube member is biased toward the valve body by a biasing spring. Therefore, a pressure of a liquid inside the valve housing and a biasing force of the spring act on the sealing tube member.

Specifically, the seating tube member is slidably mounted on an outer circumferential surface of a tube portion provided in a protruding manner at an inner end of the joint member. A gap between the outer circumferential surface of the tube portion and an inner circumferential surface of the sealing tube member is sealed by a seal ring. The biasing spring is interposed between an end surface on a side away from the valve body in the sealing tube member and the joint member. A region (spring supporting region and seal ring holding region) in the sealing tube member on the side away from the valve body constitutes a first acting surface where the liquid pressure inside the valve housing acts in a direction in which the sealing tube member is pressed to the valve body. A toric second acting surface where the liquid pressure inside the valve housing acts in a direction in which the sealing tube member separates from the valve body is provided in an outer circumferential edge portion on the valve sliding contact surface of the sealing tube member. The area of the first acting surface is set to be larger than the area of the second acting surface. A force corresponding to the area difference between the first acting surface and the second acting surface and the liquid pressure acts on the sealing tube member as a pressing force to the valve body.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

According to a control valve disclosed in Patent Literature 1, in addition to a biasing force of a spring, a biasing force generated due to a liquid pressure acts on a sealing tube member. Therefore, when an end portion of the sealing tube member is in a blocked state, the sealed state of the end portion of the sealing tube member can be favorably retained.

Here, in the control valve disclosed in Patent Literature 1, a stepped recess portion is provided in an inner circumferential edge portion on a side coining into sliding contact with a joint member of the sealing tube member, and a seal ring for sealing a gap between the sealing tube member and the joint member is interposed inside the stepped recess portion. A liquid pressure inside a valve housing is introduced into the stepped recess portion in which die seal ring is accommodated. At this time, the seal ring comes into tight contact with an inner circumferential surface of the stepped recess portion on the sealing tube member side and an outer circumferential surface of the joint member by receiving the liquid pressure inside the valve housing and presses the sealing tube member in a direction of a valve body. Therefore, a first acting surface which receives a liquid pressure inside the valve housing and biases the sealing tube member in the direction of the valve body is constituted of an end surface of the sealing lube member on a side away from the valve body, and a pressure receiving surface of the seal ring. Accordingly, in the control valve disclosed in Patent Literature 1, there is a possibility that a valve sliding contact surface of the scaling tube member is likely to be pressed to the valve body with an excessive force, a part of the liquid pressure inside the valve housing acts on the scaling tube member through the seal ring, and a pressing force acting on the sealing tube member in die direction of the valve body becomes unstable.

In addition, the control valve disclosed in Patent Literature 1 is devised such that time is no leakage of a liquid between the valve sliding contact surface of the sealing tube member and a cylinder wall of the valve body, but there is actually a minute gap for allowing sliding between the valve sliding contact surface and an outer surface of the cylinder wall, and a liquid pressure acting on a second acting surface adjacent to die valve sliding contact surface decreases due to liquid leakage through the gap. Therefore, the liquid pressure of the scaling tube member acting on the second acting surface becomes lower than the liquid pressure of the sealing tube member acting on the first acting surface. Accordingly, when the pressure of a liquid inside the valve housing (pressure difference between an upstream side anti a downstream side of a discharge port) rises, the valve sliding contact surface of the sealing tube member is pressed to the valve body with an excessive force. Therefore, an increase in the size and output of an actuator rotatively driving the valve body cannot be avoided, and abrasion is likely to occur in the sealing tube member or a bearing portion of the valve body.

A problem to be solved is to provide a control valve in which a sealing tube member is prevented from pressing a valve body with an excessive force and favorable sealing properties between the sealing tube member and the valve body can be secured.

Solution to Problem

According to an aspect of the present invention, a control valve is provided, including a valve housing which has an inflow port for causing a liquid to flow in from outside and a discharge port for discharging a liquid that has flowed in to the outside; a joint member which is joined to a circumferential edge of the discharge port, a valve body which is rotatably disposed inside the valve housing and has a circumferential wall portion in which a valve hole for communication between the inside and the outside is formed; and a sealing tube member in which one end side communicates with the discharge port, and a valve sliding contact surface slidably abutting an outer surface of the circumferential wall portion at a position where at least a part of the valve body overlaps a rotation path of the valve hole is provided on the other end side. The valve body allows an outflow of a liquid to the discharge port from an inner region of the circumferential wall portion when at a rotation position where the valve hole and the sealing tube member are allowed to communicate with each other, and the valve body controls or blocks an outflow of a liquid to the discharge port from the inner region of the circumferential wall portion when at a rotation position where the valve hole and the sealing tube member are inhibited from communicating with each other. A seal ring which receives a liquid pressure inside the valve housing and comes into tight contact with the joint member and the sealing tube member is provided between the joint member and the sealing tube member. The sealing tube member has a biasing pressure receiving surface receiving the liquid pressure inside the valve housing in a direction along a direction of the valve body. The seal ring is disposed at a position where the sealing tube member is not pressurized in the direction of the valve body. An area of the valve sliding contact surface is set to be larger than an area of the biasing pressure receiving surface.

According to the foregoing constitution, the liquid pressure inside the valve housing acts on the biasing pressure receiving surface of the sealing tithe member and a circumferential region on the valve sliding contact surface, if a pressing force in the direction of the valve body generated due to a liquid pressure acting on the sealing tube member through the biasing pressure receiving surface is a force which is equivalent to or greater than a lifting force from the valve body and acts on the sealing tube member when a liquid leaks out through a minute gap between the valve sliding contact surface and the valve body, the valve sliding contact surface of the sealing tube member can be maintained in a state of abutting an outer surface of the valve body.

The liquid pressure inside the valve housing also acts on the seal ring such that the seal ring comes into tight contact with the joint member and the sealing tube member. In the control valve according to the aspect of the present invention, the seal ring is disposed at a position where the seal ring which has received the liquid pressure inside the valve housing does not pressurize the sealing tube member in the direction of the valve body. Therefore, the liquid pressure acting on the seal ring is not applied as a force pressing the sealing tube member to the valve body. Thus, a pressing force acting on the sealing tube member in the direction of the valve body can be stabilized at all times.

In addition, in the control valve according to the aspect of the present invention, since the area of the valve sliding contact surface of the sealing tube member is larger than the area of the biasing pressure receiving surface, even if the liquid pressure inside the valve housing increases, the sealing tube member can be prevented from being pressed to the valve body with an excessive force.

The joint member may include a tube portion which protrudes from a part of the discharge port in the direction of the valve body and slidably holds an inner circumferential surface of the sealing tube member. An annular groove portion may be formed on an outer circumferential surface of the tube portion. A toric seal accommodation space may be provided between the groove portion of the tube portion and the inner circumferential surface of the sealing tube member. The seal ring which comes into tight contact with a circumferential surface of the groove portion and the inner circumferential surface of the sealing tube member may be accommodated in, the seal accommodation space. A liquid pressure chamber, into which the liquid pressure inside the valve housing is introduced, may be formed between the seal ring and a surface of the groove portion on a side away from the valve body in the seal accommodation space. A surface of the sealing tube member on a side away from the valve body may constitute the biasing pressure receiving surface.

In this case, the seal accommodation space is provided between the groove portion of the tube portion on the joint member side and the inner circumferential surface of the sealing tube member, and the seal ring is accommodated in the seal accommodation space. The liquid pressure inside the valve housing which has been introduced into the liquid pressure chamber pressurizes the seal ring. Accordingly, the seal ring comes into tight contact with the tube portion on the joint member side and the inner circumferential surface of the sealing tube member. At this time, a pressurizing force generated due to the liquid pressure acting on the seal ring acts in the direction of the valve body. However, this pressurizing force is received by the groove portion of the joint member. Therefore, a pressurizing force generated due to a liquid pressure via the seal ring is not applied to the sealing tube member. Accordingly, when the foregoing constitution is employed, a pressure receiving surface of the seal ring does not function as the biasing pressure receiving surface. Therefore, a pressing force acting on the sealing tube member in the direction of the valve body can be stabilized at all times.

In addition, when the seal ring contracts by receiving the liquid pressure, a minute pulling force accompanying the contraction thereof acts on the inner circumferential surface of the sealing tube member (part abutting the seal ring). However, the patina force acts in the direction of the valve body. Therefore, a pulling force accompanying the contraction of the seal ring is not applied as a force causing the sealing tube member to he away from the valve body. Accordingly, leakage of a liquid from a contact part between the sealing tube member and the valve body can be curbed.

The joint member may include a small diameter inner circumferential surface which slidably holds the sealing tube member, a large diameter inner circumferential surface which is formed to have an increased diameter in a stepped state from an end portion of the small diameter inner circumferential surface on a side close to the valve body, and a stepped surface which connects the small diameter inner circumferential surface and the large diameter inner circumferential surface to each other. The sealing tube member may include a small diameter outer circumferential surface which is slidably fitted into the small diameter inner circumferential surface, a large diameter outer circumferential surface which is formed to have an increased diameter in a stepped state from an end portion of the small diameter outer circumferential surface on a side close to the valve body, and a connection surface which connects the small diameter outer circumferential surface and the large diameter outer circumferential surface to each other. A toric seal accommodation space surrounded by the large diameter inner circumferential surface and the small diameter outer circumferential surface may be provided between the stepped surface of the joint member and the connection surface of the sealing tube member. The seal ring which comes into tight contact with the large diameter inner circumferential surface and the small diameter outer circumferential surface may be accommodated in the seal accommodation space. A liquid pressure chamber, into which the liquid pressure inside the valve housing is introduced, may be formed between the seal ring and the connection surface of the sealing tube member. The connection surface facing the liquid pressure chamber may constitute at least a part of the biasing pressure receiving surface.

In this case, the seal accommodation space surrounded by the large diameter inner circumferential surface and the small diameter outer circumferential surface is provided between the stepped surface of the joint member and the connection surface of the sealing tube member, and the seal ring is accommodated in the seal accommodation space. A space between the seal ring and the connection surface constitutes the liquid pressure chamber into which the liquid pressure inside the valve housing is introduced. Thus, the connection surface of the sealing tube member facing the liquid pressure chamber constitutes at least a part of the biasing pressure receiving surface. Therefore, at least a part of the biasing pressure receiving surface can be constituted with a simple structure. In addition, a pressing force in the direction of the valve body generated due to the liquid pressure inside the valve housing acts directly on the connection surface of the sealing tube member without going through the seal ring. Accordingly, a pressing force acting on the sealing tube member in the direction of the valve body can be stabilized at all times.

A joint flange coupled to a housing main body may be provided on a side radially outward with respect to a circumferential wall constituting the, large diameter inner circumferential surface of the joint member. A burr accommodation portion accommodating burrs generated when the joint flange and the housing main body, are joined to each other may be provided between the circumferential wall and the joint flange. The circumferential wall may be constituted to also serve as a burr restriction wall restricting an outflow of burrs from the burr accommodation portion.

In this case, since the circumferential wall constituting the large diameter inner circumferential surface is constituted to also serve as the burr restriction wall, compared to a case where the circumferential wall constituting the large diameter inner circumferential surface and the burr restriction wail are independently provided, a joint part of the joint member can be reduced in size.

A support surface may be provided in an end portion of the sealing tube member on a side away from the valve body. A displacement restriction spring for restricting a displacement of the sealing tube member may be interposed between the joint member and the support surface.

In this case, when the liquid pressure inside the valve housing rises rapidly, or when the liquid pressure inside the valve housing biasing the sealing tube member in the direction of the valve body is low, separation of the valve sliding contact surface of the sealing tube member from the valve body can be restricted by the displacement restriction spring.

A second stepped surface bent in a diameter reducing direction in a stepped state may be continuously provided on the small diameter inner circumferential surface of the joint member. A support surface may be provided in an end portion of the sealing tube member. A displacement restriction spring for restricting a displacement of the sealing tube member may be interposed between the second stepped surface and the support surface. A restriction tube extending in an axial direction from a radially inner end portion of the second stepped surface or the support surface may be provided in an extending manner in a part positioned on a side radially inward with respect to the displacement restriction spring.

In this case, a positional deviation of the displacement restriction spring can be restricted by the restriction tube, and the occurrence of turbulence in a liquid flowing inside the sealing tube member can be curbed. In addition, when this constitution is employed, the displacement restriction spring can be disposed compactly in a region on which a high liquid pressure inside the valve housing does not act directly.

Advantageous Effects of Invention

In the control valve described above, the seal ring is disposed at a position where the seal ring which has received a liquid pressure inside the valve housing does not pressurize the sealing tube member in the direction of the valve body. Therefore, a pressing force acting on the sealing tube member in the direction of the valve body can be stabilized at all times.

In addition, in the control valve described above, the area of the valve sliding contact surface is set to be larger than the area of the biasing pressure receiving surface. Therefore, the sealing tube member is prevented from pressing the valve body with an excessive force and favorable sealing properties between the sealing tube member and the valve body can be secured.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, a case where a control valve according to the present embodiment is employed in a vehicle cooling system for cooling an engine using cooling water will be described.

FIG. 1is a block diagram of a cooling system1.

As illustrated inFIG. 1, the cooling system1is mounted as a vehicle driving source in vehicles equipped with at least an engine2. Regarding vehicles, in addition to vehicles having only the engine2, hybrid vehicles, plug-in hybrid vehicles, or the like may be adopted.

The cooling system1has a constitution in which the engine2(ENG), a water pump3(W/P), a radiator4(RAD), an oil warmer5(O/W), a heater core6(HTR), an EGR cooler7(EGR) and a control valve8(FWV) are connected through various kinds of flow channels10to15.

An entrance side of a cooling path inside the engine2is connected to a discharge side of the water pump3, and the control valve8is connected to an exit side of the cooling path therein. A flow channel connecting the water pump3, the engine2, and the control valve8sequentially from an upstream side to a downstream side constitutes the main flow channel10in the cooling system1.

In the control valve8, the main flow channel10branches into the radiator flow channel11, the bypass flow channel12, the warming-up flow channel13, the air conditioning flow channel14, and the EGR flow channel15. Each of the downstream parts of the radiator flow channel11, the bypass flow channel12, the warming-up flow channel13, die air conditioning flow channel14, and the EGR flow channel15is connected to an intake side of the water pump3.

The radiator4for performing heat exchange between the cooling water flowing in the flow channel and outside air is interposed in the radiator flow channel11. The cooling water which has been cooled through the radiator4returns to the intake side of the water pump3.

The bypass flow channel12is a flow channel bypassing the radiator4when the temperature of the cooling water is low or the like. The cooling water returns to the intake side of the water pump3as it is.

The oil warmer5(heat exchanger for engine oil) is interposed in the warming-up flow channel13. An oil path18in which the engine oil circulating inside the engine2flows is connected to the oil wanner5. In the oil wanner5, heat exchange is performed between the cooling water flowing in the warming-up flow channel13and the engine oil. In the present embodiment, from the viewpoint of improvement in fuel efficiency or early warming-up, “the oil warmer5” is adopted as a heat exchanger. However, there are cases where the oil temperature of the engine oil becomes higher titan the water temperature of the cooling water depending on driving conditions, and therefore it is natural that the heat exchanger be used as “an oil cooler” at that time.

The heater core6is interposed in the air conditioning flow channel14. For example, the heater core6may be provided inside a duct (not illustrated) of an air conditioner. In the heater core6, heat exchange is performed between the cooling water and air-conditioning air circulating inside the duct.

The EGR cooler7is interposed in the EGR flow channel15. In the EGR cooler7, heat exchange is performed between the cooling water flowing in the EGR flow channel15and an EGR gas.

In the cooling system1described above, the cooling water which has passed through the engine2in the main flow channel10flows into the control valve8, and then the cooling water is selectively distributed to various flow channels11to15in accordance with an operation of the control valve8. Accordingly, a prompt temperature rise, high-water temperature (optimum-temperature) control, and the like can be realized, so that improvement in fuel efficiency of the vehicle is achieved.

FIG. 2is, a perspective view of the control valve8according to a first embodiment,FIG. 3is an exploded perspective view of the same control valve8.

As illustrated inFIGS. 2 and 3, the control valve8includes a valve housing21having an inflow port37and a plurality of discharge ports41A,41B,41C,41D, and41E; a valve body22turnably disposed inside the valve housing21, and a drive unit23rotatively driving the valve body72.

The valve housing21has a bottomed tubular housing main body25internally accommodating the valve body22(having a valve accommodation portion), and a lid body26for closing an opening portion of the housing main body25. In the following description, a direction along an axis O of the valve housing21will be simply referred to as an axial direction. The valve housing21is formed to have a tubular shape elongated in the axial direction. The inflow port37into which the cooling water (liquid) flows from outside (engine2), and the plurality of discharge ports41A,41B,41C,41D, and41E which are respectively connected to the radiator flow channel11, the EGR flow channel15, the bypass flow channel12, the warming-up flow channel13, and the air conditioning flow channel14illustrated inFIG. 1and discharge the cooling water (liquid) which has flowed into the valve housing21to each of the flow channels are provided in a circumferential wall of the valve housing21.

The inflow port37is provided in an outer circumference near one end side of the valve housing21in the axial direction, and the discharge ports41A,41B,41C,41D, and41E are provided at suitable places separated from each other in the axial direction and a circumferential direction in the outer circumference of the valve housing21. As illustrated inFIG. 3, each of the discharge ports41A,41B,41C,41D, and41E is formed in an outer circumferential wall of the housing main body25. A joint member43for connecting a piping for discharging is joined to a circumferential edge of each of the discharge ports41A,41B,41C,41D, and41E.

A sealing mechanism110including a sealing tube member111(which will be described below), a seal ring112, and a displacement restriction spring113is provided inside each of the discharge ports41A,41C,41D, and41E except for the discharge port41B connected to the EGR flow channel15.

A fail opening70constituted to be able to be opened and closed by a thermostat45is formed in a part facing the inflow port37inside the valve housing21. The discharge port41B connected to the EGR flow channel15opens in a direction orthogonal to an opening direction of the fail opening70. According to this constitution the cooling water which has flowed into the valve housing21from the inflow port37touches the thermostat45and then flows into the EGR flow channel15through the discharge port41B. Therefore, a flow toward the discharge port41B can be made around the thermostat45inside the valve housing21, and formation of still points around the thermostat45is curbed.

Regarding the discharge ports41A,41C,41D, and41E and the sealing mechanism110which is provided inside each thereof, although the sizes and the shapes are slightly different from each other, all have basic structures similar to each other. Therefore, hereinafter, the discharge port41D connected to the warming-up flow channel13and the sealing mechanism110provided therein are taken as representatives thereof, and these and the valve body22will be described in detail with reference toFIGS. 3 and 4.

FIG. 4is a cross-sectional view of the control valve8along line IV-IV inFIG. 2, andFIG. 5is an enlarged view illustrating a part V inFIG. 4.

As illustrated inFIG. 3, the valve body22is rotatably accommodated inside the valve housing21. The valve body22includes a cylinder wall27disposed coaxially with the axis O of the valve housing21. The cylinder wall27is the circumferential wall portion disclosed in the claims. A plurality of valve holes28A,28C,28D, and28E through which the inside and the outside of the cylinder wall27communicate with each other are formed at suitable places in the cylinder wall27. The valve holes28A,28C,28D, and28E are provided in a manner corresponding to the discharge ports41A,41C,41D, and41E. The valve holes28A,28C,28D, and28E are provided to be separated from each other in the axial direction of the cylinder wall27. Each of the discharge ports41A,41C,41D, and41E of the valve housing21is formed at a position where at least a part thereof overlaps a rotation path of each of the valve holes28A,28C,28D, and28E of the cylinder wall27in the direction of the axis O.

As illustratedFIGS. 4 and 5, the sealing tube member111of the sealing mechanism110is formed to have substantially a cylindrical shape in its entirety. In the sealing tube member111, an inner circumferential surface on one end side is slidably held by the joint member43of the corresponding discharge port41D. In this state, the sealing tube member111communicates with a path hole38of the corresponding joint member43. In addition, an arc-shaped valve sliding contact surface29is provided on an end surface of the sealing tube member111on the other end side. The valve sliding contact surface29slidably abuts an outer surface of the cylinder wall27at a position where at least a part of the valve body22overlaps the rotation path of the corresponding valve hole28D. Both the sealing tube member111and the cylinder wall27of the valve body22are formed of a resin material.

The valve body22allows an outflow of the cooling water to the discharge port41D from an inner region of the cylinder wall27via the sealing tube member111when at a rotation position where the valve hole28D and the sealing tube member111corresponding to the valve hole28D communicate with each other. In addition, the valve body22blocks an outflow of the cooling water to the discharge port41D from the inner region of the cylinder wall27via the sealing tube member111when at a rotation position where the valve hole28D and the sealing tube member111corresponding to the valve hole28D do not communicate with each other.

The rotation position of the valve body22is suitably adjusted by the drive unit23provided in a bottom wall portion of the housing main body25(refer toFIGS. 2 and 3). The drive unit23is constituted such that a motor (not illustrated), a deceleration mechanism, a control board, and the like ate stored inside a casing23a.

As illustrated inFIGS. 4 and 5, the joint member43includes a joint main body portion43ato which the piping for discharging is connected, a joint flange51projected radially outward from a base end of the joint main body portion43a,and a tube portion60protruding from an inner circumferential edge portion of the joint flange51in an inward direction of the housing main body25. The joint flange51is joined to an end surface of a circumferential wall25aconstituting the discharge port41D of the housing main body25by suitable means such as welding or screwing. The tube portion60protrudes in a direction of the valve body22from a pan of the discharge port41D of the housing main body25.

The scaling tube member111includes a cylindrical fitting wall111aslidably fined on an outer circumferential surface of the tube portion60of the joint member43. The fitting wall111ais disposed inside a space portion surrounded by the circumferential wall25aof the valve housing21and the joint member43. An end portion of the sealing tube member111on the valve body22side constitutes the valve sliding contact surface29which comes into sliding contact with the outer circumferential surface of the cylinder wall27of the valve body22. A joint side end surface66on a side opposite to the valve sliding contact surface29of the sealing tube member111is a flat surface having a uniform width.

The displacement restriction spring113is interposed between the joint side end surface66of the sealing rube member111and the joint flange51of the joint member43. The displacement restriction spring113restricts a displacement of the sealing tube member111in a direction of separation from the valve body22. In the case of the present embodiment, the displacement restriction spring113functions to maintain the sealing tube member111at an initial position (position where the valve sliding contact surface29comes into contact with the outer circumferential surface of the valve body22) in an assembled state. The displacement restriction spring113is set such that no significant biasing force acts on the sealing tube member111when the sealing tube member111is at the initial position.

An introduction path48is formed between the circumferential wall25aof the valve housing21and the outer circumferential surface of the sealing tube member111. The introduction path48causes the liquid pressure of the cooling water inside the valve housing21to act on the joint side end surface66of the sealing tube member111. The joint side end surface66receives the liquid pressure of the cooling water inside the valve housing21in the direction of the valve body22. In the present embodiment, the joint side end surface66constitutes a biasing pressure receiving surface.

In addition, a toric groove portion61is formed on the outer circumferential surface of the tube portion60of the joint member43. A toric seal accommodation space62is provided between the groove portion61of the tube portion60and the inner circumferential surface of the sealing tube member111. The seal ring112which comes into tight contact with a circumferential surface61aof the groove portion61on a bottom portion side and the inner circumferential surface of the sealing tube member111is accommodated in the seal accommodation space62.

The seal ring112is an annular elastic member having a Y-shaped cross section and is accommodated in the seal accommodation space62such that a Y-shaped opening side is directed to a side away from the valve body22. In the seal ring112, each of side end portions of a Y-shaped bifurcated portion comes into tight contact with the circumferential surface61aof the groove portion61on the bottom portion side and the inner circumferential surface of the sealing tube member111. A space between the seal ring112and the end surface of the groove portion61on the side away from the valve body22constitutes a liquid pressure chamber47into which the liquid pressure of the cooling water inside the valve housing21is introduced. In addition, an introduction path63is secured between the tube portion60of the joint member43and die fitting wall111aof the sealing tube member111. The introduction path63introduces the liquid pressure of the cooling water inside the valve housing21into the liquid pressure chamber47via the joint side end surface66.

In addition, on the valve sliding contact surface29of the sealing tube member111, the entire region over the sealing tube member111from the radially outer end to the inner end is formed to have a radius of the same curvature as a region on the outer surface of the cylinder wall27of the valve body22abutting the scaling tube member111. Accordingly, the entire region over die sealing tube member111from the radially outer end to the inner end on the valve sliding contact surface29basically abuts the outer surface of the cylinder wall27. However due to manufacturing errors, assembly errors, or the like of the sealing tube member111, a gap between a radially outer region on the valve sliding contact surface29and the cylinder wall27may be slightly larger.

Here, an area S1of the joint side end surface66(biasing pressure receiving surface) in the scaling tube member111and an area S2of the valve sliding contact surface29are set to satisfy the following Expressions (1) and (2).
S1<S2≤S1/k(1)
α≤k<1   (2)

Here, k indicates u pressure reduction constant of a liquid flowing through a minute gap between the valve sliding contact surface and the valve body, and α indicates a lower limit value for the pressure reduction constant determined based on physical properties of a liquid.

The area S1of the joint side end surface66and the area S2of the valve sliding contact surface29mean areas when projected on a surface orthogonal to the axial direction of the sealing tube member111.

The factor α in Expression (2) indicates a standard value of the pressure reduction constant determined based on the kind of a liquid, the usage environment (for example, the temperature), and the like, and α=½ is established in a case of using water under an ordinary usage condition. When the physical properties of a liquid to be used change, the relationship is changed to α=⅓ or the like.

In addition, the pressure reduction constant k in Expression (2) becomes α (for example, ½), which is the standard value of the pressure reduction constant when the valve sliding contact surface29evenly cones into contact with the cylinder wall27from the radially outer end to the inner end.

In addition, due to manufacturing errors or assembly errors of the sealing tube member111, foreign substances, or the like, an abutting gap between the valve sliding contact surface29and the cylinder wall27may be no longer even over the valve sliding contact surface29from the radially outer end to the inner end, and the abutting gap of an outer end may increase. In this case, the pressure reduction constant k in Expression (2) is gradually approximated to k=1.

In the control valve8of the present embodiment, on the premise that there is a minute gap between the valve sliding contact surface29of the sealing tube member111and the cylinder wall27(valve body22) in order to allow sliding between both thereof, the relationship between the areas S1and S2of the joint side end surface66and the valve sliding contact surface29is determined by Expressions (1) and (2).

That is, the pressure of the cooling water inside the valve housing21acts on the joint side end surface66of the sealing tube member111as it is. However, the pressure of the cooling water inside the valve housing21does not act on the valve sliding contact surface29as it is. The pressure acts thereon while being accompanied by pressure reduction when the cooling water flows from the radially outer end toward the inner end through the minute gap between the valve sliding contact surface29and the cylinder wall27. At this time, the pressure of the cooling water inside the valve housing21flowing through the minute gap is gradually reduced toward the inside of the discharge port41D under a low pressure, and the pressure tends to push up the sealing tube member111in the direction of separation from the valve body22.

A force realized by multiplying the area S1of the joint side end surface66by a pressure P inside the valve housing21acts on the joint side end surface66of the sealing tube member111as it is, and a force realized by multiplying the area52of the valve sliding contact surface29by the pressure P inside the valve housing21and the pressure reduction constant k acts on the valve sliding contact surface29of the sealing tube member111.

In the control valve8of the present embodiment, as it is clear from Expression (1), the areas S1and S2are set such that k×S2≤S1is established. Therefore, the relationship of P×k×S2≤P×S1is also established.

Accordingly, a force F1(F1=P×S1) acting on the joint side end surface66of the sealing tube member111in a pressing direction becomes equivalent to or greater than a force F2(F2=P×k×S2) acting on the valve sliding contact surface29of the sealing tube member111in a lifting direction. Thus, in the control valve8of the present embodiment, the end portion of the sealing tube member111can be closed by the cylinder wall27of the valve body22based on only the relationship of the pressure of the cooling water inside the valve housing21.

Meanwhile, in the control valve8of the present embodiment, as indicated in Expression (1), the area S1of the joint side end surface66of the sealing tube member111is smaller than the area S2of the valve sliding contact surface29. Therefore, in the control valve8, even if the pressure of the cooling water inside the valve housing21increases, the valve sliding contact surface29of the sealing tube member111can be prevented from being pressed to the cylinder wall27of the valve body22with an excessive force. Accordingly, when the control valve8is employed, an increase in the size and output of the drive unit23rotatively driving the valve body22can be avoided, and early abrasion in the sealing tube member111or a bearing portion71(refer toFIG. 3) of the valve body22can be curbed.

Here, using cooling water (k in Expression (2) has a relationship of k=0.5), a leakage test of cooling liquid and an abrasion test of the valve sliding contact surface29were performed with respect to the control valve8of the embodiment in which the area S1of the joint side end surface66(biasing pressure receiving surface) and the area52of the valve sliding contact surface29satisfied. Expression (1), and control valves of two comparative examples in which the areas S1and S2did not satisfy Expression (1). The following Table 1 and the graph inFIG. 6show the results.

In Table 1 andFIG. 6, No. 2 indicates the control valve8of the embodiment satisfying Expression (1), and No. 1 indicates the control valve of the comparative example in which the areas S1and S2have relationships of S1>S2and S2<S1/k. In addition, No. 3 indicates the control valve of the comparative example in which the areas S1and S2have relationships of S1<S2and S2>S1/k.

TABLE 1S1S2SealingSealingNo.[mm2][mm2]Region of S2propertiesabrasion1207.3165.9Beyond the rangeFairConsiderableof ExpressionSmaller than S12207.3311.0Within the rangeFairLittleof Expression3207.3472.7Beyond the rangePoorLittleof ExpressionLarger than S1/k*Tested by water. The pressure reduction constant k is set to 0.5.

In the leakage test of cooling liquid, the rotation position of the valve body22of the control valve8was set to a position where the valve hole28D of the valve body22and the sealing tube member111corresponding to the valve hole25D did not communicate with each other, in this state, the leakage rate of the cooling liquid from the discharge port when the pressure at the inflow port was gradually increased was measured. In addition, in the abrasion test of the valve sliding contact surface29, the abrasion state of the valve sliding contact surface29when the pressure at the inflow port was, uniform and the cylinder wall27of the valve body22was rotated for a predetermined time was judged.

As it is clear from Table 1 andFIG. 6, in the comparative example of No. 1 in which the area S2of the valve sliding contact surface29was smaller than the area S1of the joint side end surface (biasing pressure receiving surface)66(S1>S2), the leakage rate of the cooling water was low. However, in the comparative example of No. 1, abrasion on the valve sliding contact surface29was greater than that in the control valves of No. 1 and No. 3. In addition, in the comparative example of No. 3 in which the area S2of the valve sliding contact surface29was larger than S1/k, there was little abrasion on the valve sliding contact surface29. However, in the comparative example of No. 3, the leakage rate of the cooling water was higher than a required value.

In contrast, in the control valve8of the embodiment, that is, No. 2 in which the areas S1and S2satisfied Expression (1), there was little abrasion on the valve sliding contact surface29, and there was little leakage of the cooling water within the required value.

As described above, in the control valve8of the present embodiment, the area S2of the valve sliding contact surface29is set to be larger than an area S1of a connection surface36(biasing pressure receiving surface) within a range in which pressing force in the direction of the valve body22generated due to the liquid pressure acting on the sealing tube member111does not fall below a lifting force acting on the sealing tube member111. Therefore, in the control valve8of the present embodiment, the sealing tube member111is prevented from pressing the cylinder wall27of the valve body22with an excessive force, and the end portion of the sealing tube member111can be appropriately opened and closed by the cylinder wall27of the valve body22.

In addition, in the control valve8of the present embodiment, the seal ring112is disposed at a position where the seal ring112which has received the liquid pressure inside the valve housing21does not pressurize the sealing tube member111in the direction of the valve body22. Therefore, in the control valve8of the present embodiment, the liquid pressure acting on the seal ring112is not applied as a force pressing the sealing tube member111to the valve body22.

Specifically, in the control valve8of the present embodiment, the annular groove portion61is provided on the outer circumferential surface of the tube portion60provided the joint member43in a protruding manner, and the toric seal accommodation space62is provided between the groove portion61of the tube portion60and the inner circumferential surface of the sealing tube member111. Thus, the seal ring112which comes into tight contact with a circumferential surface of the groove portion61and the inner circumferential surface of the sealing tube member111is accommodated in the seal accommodation space62. A space between the seal ring112and a surface of the groove portion61on the side away from the valve body22inside the seal accommodation space62constitutes the liquid pressure chamber47. In addition, the joint side end surface66of the sealing tube member111constitutes a biasing pressure receiving surface.

Therefore, a pressurizing force generated due to the liquid pressure inside the valve housing21acting on the seal ring112acts in the direction of the valve body22. However, this pressurizing force is received by the groove portion61of the joint member43. Accordingly, a pressurizing force generated due to the liquid pressure via the seal ring112is not applied to the sealing tube member111. Thus, in the control valve8of the present embodiment, a pressing force acting on the sealing tube member111in the direction of the valve body22can be stabilized at all times without being affected by the state of the seal ring112.

In addition, in the control valve8of the present embodiment, when the seal ring112contracts by receiving the pressure inside the liquid pressure chamber47, a minute pulling force accompanying the contraction thereof acts on the inner circumferential surface of the sealing tube member111. However, a pulling direction thereof acts in the direction of the valve body22. Accordingly, in the control valve8of the present embodiment, a pulling force accompanying the contraction of the seal ring112is not applied as a force causing the sealing tube member111to be away from the valve body22. Therefore, leakage of the cooling water from the valve sliding contact surface29of the sealing tube member111can be further curbed.

In addition, in the control valve8of the present embodiment, the valve sliding contact surface29of the sealing tube member111is constituted of an are surface having a radius of the same curvature as a region on the outer surface of the cylinder wall27of the valve body22abutting the sealing tube member111. Therefore, the entire region over the valve sliding contact surface29easily and evenly abuts the outer surface of the cylinder wall27, and substantially even pressure reduction is likely to occur over the valve sliding contact surface29from the radially outer end to the inner end. Accordingly, when the control valve8is employed, a lifting force acting on the valve sliding contact surface29of the sealing tube member111is stabilized, and sealing performance of the sealing tube member111with respect to the valve body22is stabilized.

Subsequently, a second embodiment illustrated inFIGS. 7 and 8will be described. In the following description including description of modification examples (which will be described below), the same reference signs are applied to parts in common with the first embodiment, and duplicate description will be omitted.

FIG. 7is a cross-sectional view similar to that inFIG. 4of the first embodiment regarding a control valve8A of the second embodiment.FIG. 8is an enlarged view illustrating a part VIII inFIG. 7.

A joint member43A includes a small diameter inner circumferential surface30slidably holding an outer circumferential surface in a region of a sealing tube member111A on the side away from the valve body22, and a large diameter inner circumferential surface31formed to have an increased diameter in a stepped state from an end portion on the small diameter inner circumferential surface30on a side close to the valve body22. The small diameter inner circumferential surface30and the large diameter inner circumferential surface31are connected to each other through a flat toric first stepped surface32(stepped surface) extending in a direction orthogonal to these. In addition, in the end portion on the small diameter inner circumferential surface30of the joint member43A on the side away from the valve body22, a flat toric second stepped surface33which is bent in a diameter reducing direction in a stepped state and connects the small diameter inner circumferential surface30and the path hole38to each other is continuously provided.

In addition, on a side radially outward with respect to a circumferential wall50constituting the large diameter inner circumferential surface31of the joint member43A, the joint flange51to be joined to the housing main body25is formed to project radially outward.

A burr accommodation portion52for accommodating burrs generated when the joint flange51is joined to the housing main body25through vibration welding or the like is provided between the circumferential wall50of the joint member43A and the joint flange51. The burr accommodation portion52is constituted of recessed portions formed on surfaces of the joint flange51and the housing main body25facing each other. The circumferential wall50constituting the large diameter inner circumferential surface31also serves as a burr restriction wall restricting an outflow of burrs from the burr accommodation portion52to the inside of the valve housing21.

The sealing tube member111A includes a small diameter outer circumferential surface34slidably fitted inward on the small diameter inner circumferential surface30of the joint member43A, and a large diameter outer circumferential surface35formed to have an increased diameter in a stepped state from an end portion on the small diameter outer circumferential surface34on the side close to the valve body22. The small diameter outer circumferential surface34and the large diameter outer circumferential surface35are connected to each other through the toric connection surface36extending in a direction orthogonal to these. In addition, in the end portion on the small diameter outer circumferential surface34of the sealing tube member111A on the side away from the valve body22, a flat toric support surface39which is bent in the diameter reducing direction substantially at a right angle is continuously provided.

In addition, at an end edge on the inner circumferential surface of the sealing tube member111A on the side close to the valve body22, a toric thinned portion49is provided to be increased in diameter in a stepped state.

A toric seal accommodation space46surrounded by the large diameter inner circumferential surface31and the small diameter outer circumferential surface34is provided between the first stepped surface32of the joint member43A and the connection surface36of the sealing tube member111A. The seal ring112is accommodated in this seal accommodation space46.

The seal ring112is an annular elastic member having a V-shaped cross section and is accommodated in the seal accommodation space46such that the Y-shaped opening side is directed to the connection surface36side. In the seal ring112, each of the side end portions of the Y-shaped bifurcated portion comes into tight contact with the large diameter inner circumferential surface31and the small diameter outer circumferential surface34. A space between the seal ring112and the connection surface36of the sealing tube member111A constitutes the liquid pressure chamber47into which the liquid pressure of the cooling water inside the valve housing21is introduced. In addition, the introduction path48is provided between the large diameter inner circumferential surface31of the joint member43A and the large diameter outer circumferential surface35of the sealing tube member111A. The introduction path48introduces the liquid pressure of the cooling water inside the valve housing into the liquid pressure chamber47.

It is preferable that a gap be formed between the connection surface36of the sealing tube member111A and the seal ring112. For example, when the sealing tube member111A slides on the small diameter inner circumferential surface30of the joint member43A due to a foreign substance, the sealing tube member111A is prevented from pressing the seal ring112due to the presence of the gap, and therefore sealing properties of the seal ring112are retained. In addition, since each of the side end portions of the bifurcated portion of the seal ring112comes into tight contact with the large diameter inner circumferential surface31and the small diameter outer circumferential surface34, the liquid pressure of the cooling water inside the valve housing21does not act on the support surface39.

The liquid pressure of the cooling water inside the valve housing21acts on the connection surface36of the sealing tube member111A. The connection surface36is directed in a direction opposite to the valve sliding contact surface29on the sealing tube member111A and is pressurized in the direction of the valve body22by receiving the liquid pressure of the cooling water inside the valve housing21. In the present embodiment, the connection surface36constitutes a biasing pressure receiving surface in the sealing tube member111A.

In addition, the displacement restriction spring113for restricting a displacement of the sealing tube member111A in the direction of separation from the valve body22is interposed between the second stepped surface33of the joint member43A and the support surface39of the sealing tube member111A. In the case of the present embodiment, the displacement restriction spring113functions to maintain the sealing tube member111A at an initial position (position where the valve sliding contact surface29comes into contact with the outer circumferential surface of the valve body22) in an assembled state, and the displacement restriction spring113is set such that no significant biasing force to the sealing tube member111A acts when the sealing tube member111A is at the initial position.

In addition, on the valve sliding contact surface29of the sealing tube member111A, the entire region over the sealing tube member111A from the radially outer end to the inner end is formed to have a radius of the same curvature as a region on the outer surface of the cylinder wall27of the valve body22abutting the sealing tube member111A. Accordingly, the entire region over the sealing tube member111A from the radially outer end to the inner end on the valve sliding contact surface29basically abuts the outer surface of the cylinder wall27.

In the present embodiment, the area S1of the connection surface36(biasing pressure receiving surface) in the sealing tube member111A and the area S2of the valve sliding contact surface29are set to satisfy Expressions (1) and (2) described in the first embodiment.

As described above, in the control valve8A of the present embodiment, similar to the first embodiment, the area S2of the valve sliding contact surface29is set to be larger than the area S1of the connection surface36(biasing pressure receiving surface) within a range in which a pressing force in the direction of the valve body22generated due to the liquid pressure acting on the sealing tube member111A does not fall below a lifting force acting on the sealing tube member111A. Therefore, in the control valve8A of the present embodiment, the sealing tube member111A is prevented from pressing the cylinder wall27of the valve body22with an excessive force, and the end portion of the sealing tube member111A can be appropriately opened and closed by the cylinder wall27of the valve body22.

In addition, in the control valve8A of the present embodiment, the seal accommodation space46surrounded by the large diameter inner circumferential surface31and the small diameter outer circumferential surface34is provided between the first stepped surface32of the joint member43A and the connection surface36of the sealing tube member111A, and the seal ring112is accommodated in the seal accommodation space46. Thus, a space between the seal ring112and the connection surface36constitutes the liquid pressure chamber47, and the connection surface36of the sealing tube member111A facing the liquid pressure chamber47constitutes the biasing pressure receiving surface. Therefore, the biasing pressure receiving surface can be constituted with a simple structure, and a pressing force acting on the sealing tube member111A in the direction of the valve body can be stabilized at all times.

That is, in the case of the structure of the present embodiment, since the liquid pressure of the cooling water inside the valve housing21acts directly on the connection surface36on the sealing tube member111A without going through the seal ring112, the sealing tube member111A is pressed in the direction of the valve body with a stable force, without being affected by the state of the seal ring112.

In addition, in the control valve8A of the present embodiment, since the liquid pressure inside the valve housing21no longer acts on the small diameter inner circumferential surface30of the joint member43A, a significant force generated due to the liquid pressure in a direction of separation from the housing main body25is unlikely to act on the joint member43A. Accordingly, the joined state between the joint member43A and the housing main body25can be stably maintained.

That is, in the structure of the control valve8A according to the present embodiment, a force in the separation direction generated due to the liquid pressure acting on the joint member43A can be curbed.

Moreover, in the control valve8A of the present embodiment, the burr accommodation portion52accommodating burrs generated when the joint flange51and the housing main body25are welded to each other is provided between the circumferential wall50of the joint member43A and the joint flange51, and the circumferential wall50is constituted to also serve as the burr restriction wall restricting an outflow of burrs from the burr accommodation portion52. Therefore, compared to a case where the circumferential wall50constituting the large diameter inner circumferential surface31and the burr restriction wall are individually provided, a joint part of the joint member43A can be reduced in size.

In addition, in the control valve8A of the present embodiment, the second stepped surface33which is bent in the diameter reducing direction in a stepped state and connects the small diameter inner circumferential surface30and the path hole38to each other is continuously provided in the end portion on the small diameter inner circumferential surface30of the joint member43A on the side away from the valve body22, and the displacement restriction spring113is interposed between the second stepped surface33and the support surface39of the end portion of the sealing tube member111A. Therefore, even when a significant force acts on the sealing tube member111A in the lifting direction for some reason or when the pressure inside the valve housing21biasing the sealing tube member111A in the direction of the valve body22is low, an excessive displacement of the sealing tube member111A in the lifting direction can be restricted by the displacement restriction spring113. Accordingly, when this constitution is employed, it is difficult for the sealing tube member111A to be lifted from the outer surface of the cylinder wall27, and therefore sealing performance of the sealing tube member111A is further stabilized.

In addition, when this constitution is employed, the displacement restriction spring113can be disposed compactly in a region on which a high liquid pressure inside the valve housing21does not act directly.

In addition, in the control valve8A of the present embodiment, the valve sliding contact surface29of the sealing tube member111A is constituted of an are surface having a radius of the same curvature as a region on the outer surface of the cylinder wall27of the valve body22abutting the sealing tube member111A. Therefore, the entire region over the valve sliding contact surface29easily and evenly abuts the outer surface of the cylinder wall27, and substantially even pressure reduction is likely to occur over the valve sliding contact surface29from the radially outer end to the inner end. Accordingly, when the control valve8A is employed, a lifting force acting on the valve sliding contact surface29of the sealing tube member111A is stabilized, and sealing performance of the sealing tube member111A with respect to the valve body22is stabilized.

In addition, the displacement restriction spring113biases a position of the sealing tube member111A where the valve sliding contact surface29of the sealing tube member111A is deviated radially inward at all times. Accordingly, even when abrasion on the valve sliding contact surface29proceeds from a side radially outward by being used over time, a radially inner region on the valve sliding contact surface29can be reliably brought into press contact with the outer surface of the cylinder wall27due to a pressing load of the displacement restriction spring113. Thus, when the control valve8A of the present embodiment is employed, sealing performance of the valve sliding contact surface29of the sealing tube member111A can be highly maintained over a long period of time. In, addition, since the liquid pressure of the cooling water inside the valve housing21does not act on the support surface39which the displacement restriction spring113abuts, abrasion on the valve sliding contact surface29can be curbed without causing the valve sliding contact surface29to be excessively pressed to the outer surface of the cylinder wall27.

FIG. 9is a cross-sectional view similar to that inFIG. 7of the second embodiment regarding a control valve108according to a third embodiment.

The basic constitution of the control valve108of the third embodiment is substantially similar to the constitution of that in the second embodiment.

In the control valve108, a restriction tube55extending in the direction of the valve body22and restricting a displacement of the displacement restriction spring113to a side radially inward is provided in an extending manner in a radially inner edge portion of the second stepped surface33of the joint member43A. The constitution is otherwise similar to that in the second embodiment.

The control valve108of the present embodiment can achieve basic effects similar to those in the second embodiment. Moreover, in the control valve108of the present embodiment, since the restriction tube55is provided in an extendings manner in the radially inner edge portion of the second stepped surface33of the joint member43A, a displacement of the displacement restriction spring113to a side radially inward can be restricted by the restriction tube55, and the occurrence of turbulence in a flow of the cooling water from the inside of the sealing tube member111A toward the path hole38can be curbed by the restriction tube55.

In the present embodiment, the restriction tube55is provided at the radially inner end edge of the second stepped surface33of the joint member43A. However, as illustrated inFIG. 14, a restriction tube155may be provided in the radially inner edge portion on the support surface39of the sealing tube member111A. The restriction tube155extends in the axial direction from the radially inner edge portion on the support surface39and is positioned on a side radially inward with respect to the displacement restriction spring113.

In addition.FIGS. 10 to 13are cross-sectional views similar to that inFIG. 7illustrating modification examples of the foregoing embodiment.

In the modification example illustrated inFIG. 10, a stepped diameter decreasing portion56gently decreased in diameter in a stepped shape from the thinned portion49toward the side away from the valve body22is formed on the inner circumferential surface of the sealing tube member111A. In the case of this modification example, since the inner circumferential surface of the sealing tube member111A is decreased in diameter in a stepped shape from the thinned portion49toward a side separated from the valve body22, when the cooling water flows into the sealing tube member111A from the valve body22, the occurrence of turbulence in a part of the thinned portion49can be curbed.

In the modification example illustrated inFIG. 11, a tapered diameter decreasing portion57continuously decreased in diameter in a tapered shape from the thinned portion49toward the side away from the valve body22is formed on the inner circumferential surface of the sealing tube member111A. In the case of this modification example, since the inner circumferential surface of the sealing tube member111A is continuously decreased in diameter from the thinned portion49toward the side separated from the valve body22, when the cooling water flows into the sealing tube member111A from the valve body22, the occurrence of turbulence in a part of the thinned portion49can be more effectively curbed.

In the modification example illustrated inFIG. 12, an enlarged outer circumferential surface160increased in diameter in a stepped state from the large diameter outer circumferential surface35of the sealing tube member111A is continuously provided. An end portion of the enlarged outer circumferential surface160on the valve body22side is formed to continuously come into contact with the valve sliding contact surface29. The stepped surface connecting the large diameter outer circumferential surface35and the enlarged outer circumferential surface160to each other constitutes an auxiliary pressure receiving surface58directed in a direction opposite to the valve sliding contact surface29. In the case of this modification example, the liquid pressure of the cooling water inside the valve housing21acts on the auxiliary pressure receiving surface58. Accordingly, for example, even when the size of the seal ring112is small and the liquid pressure acting on the connection surface36is low, sealing properties of the sealing tube member111A can be enhanced by setting the valve sliding contact surface29based on the foregoing expressions.

In the present modification example, the connection surface36of the sealing tube member111A and the auxiliary pressure receiving surface58constitute a biasing pressure receiving surface.

In the modification example illustrated inFIG. 13, a contracted outer circumferential surface161decreased in diameter in a stepped state from the large diameter outer circumferential surface35is continuously provided in the end portion of the large diameter outer circumferential surface35of the sealing tube member111A on the side close to the valve body22. The end portion of the contracted outer circumferential surface161on the valve body22side is formed to continuously come into contact with the valve sliding contact surface29. The stepped surface connecting the large diameter outer circumferential surface35and the contracted outer circumferential surface161to each other constitutes an auxiliary pressure receiving surface59directed in the same direction as the valve sliding contact surface29. In the case of this modification example, since the liquid pressure of the cooling water inside the valve housing21acts on the auxiliary pressure receiving surface59, a pressing force of the sealing tube member111A with respect to the valve body22can be curbed. Accordingly, for example, even when the size of the seal ring112is large and the liquid pressure acting on the connection surface36is high, excessive pressing of the sealing tube member111A is prevented by setting the valve sliding contact surface29based on the foregoing expressions, and sealing properties can be enhanced.

In the present modification example, a part on the connection surface36of the sealing tube member111A from which the part corresponding to the area of the auxiliary pressure receiving surface59is subtracted constitutes a biasing pressure receiving surface.

In this specification, when a sealing tube member includes the same area parts on which the same pressure acts in directions opposite to each other, “the biasing pressure receiving surface” means a part on the pressure receiving surface opposite to the valve sliding contact surface, except for a region of the same area parts.

Hereinabove, preferable examples of the present invention have been described. However, the present invention is not limited to these examples. The constitutions can be subjected to addition, omission, replacement, and other changes within a range not departing from the gist of the present invention. The present invention is not limited by the foregoing description and is limited by only the scope of the accompanying claims.

For example, in the foregoing embodiments, when the sealing tube member111or111A is at the initial position, the displacement restriction spring113is set such that its biasing force does not substantially act on the sealing tube member111or111A. However, as long as the sealing tube member111or111A is within a range in which it is not pressed to the valve body22with an excessive force, a biasing force of the displacement restriction spring113may act on the sealing tube member111or111A even when the sealing tube member111or111A is at the initial position.

In the foregoing embodiments, a case where each of the valve body22(cylinder wall27) and the valve housing21(circumferential wall of the housing main body25) is formed to have a cylindrical shape (having a uniform diameter in the axial direction throughout the entirety) has been described. However, the embodiments are not limited to this constitution. That is, as long as the cylinder wall27has a constitution in which it can rotate inside the circumferential wall of the housing main body25, the outer diameter of the cylinder wall27and the inner diameter of the circumferential wall of the housing main body25may be changed in the axial direction. In this case, for example, the cylinder wall27and the circumferential wall of the housing main body25can employ various shapes, such as a spherical shape (shape decreased in diameter toward both end portions from a middle portion in the axial direction), a saddle type (shape increased in diameter toward both end portions from a middle portion in the axial direction), a shape having a three-dimensionally curved surface such as a shape in which a plurality of spherical shapes or saddle types are connected in the axial direction, a tapered shape (shape of which the diameter gradually changes from a first side to a second side in the axial direction), and a stepped shape (shape of which the diameter changes in steps from a first side to a second side in the axial, direction).

In addition, in the foregoing embodiments, a case where the seal ring112is constituted of an annular elastic member having a Y-shaped cross section has been described. However, the embodiments are not limited to this constitution. The seal ring112can employ various shapes such as an annular elastic member having an O-shaped cross section or an X-shaped cross section.

REFERENCE SIGNS LIST

25Housing main body

30Small diameter inner circumferential surface

31Large diameter inner circumferential surface

34Small diameter outer circumferential surface

35Large diameter outer circumferential surface

41A41C,41D,41E Discharge port

42Discharging hole portion

43,43A Joint member

46Seal accommodation space

47Liquid pressure chamber

52Burr accommodation portion

62Seal accommodation space

66joint side end surface (biasing pressure receiving surface)

111,111A Sealing tube member

113Displacement restriction spring

S1Area of biasing, pressure receiving surface

S2Area of valve sliding contact surface