Patent Publication Number: US-2015075453-A1

Title: Rotary valve

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation application, filed under 35 U.S.C. §111(a), of International Application PCT/JP2013/064415, filed on May 23, 2013, which claims the foreign priority benefit of Japanese Patent Application No. 2012-118977, filed May 24, 2012, the disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field 
     Embodiments of the present invention relate to a rotary valve including a rotor which is rotated to open and close a flow passage. 
     2. Description of Related Art 
     In an engine (internal combustion engine) of a vehicle such as an automobile, for the purpose of enhancing the warm-up performance of the engine, enhancing the fuel efficiency by operating the engine at an optimal temperature, and the like, it is considered that a bypass passage through which cooling water bypasses a radiator and is returned to the engine as it is provided separately from a main passage through which the cooling water is circulated between the engine and the radiator, a cooling water control valve is provided in the main passage, and by controlling the opening degree of the cooling water control valve according to the temperature of the cooling water and the other values, the amount of the cooling water which flows through the main passage and is cooled by the radiator is controlled. Note that, the cooling water is circulated by a pump driven by the engine, and during an operation of the engine, the cooling water is mainly circulated through the main passage in a case where the cooling water control valve is opened, and is circulated through the bypass passage in a case where the cooling water control valve is closed. 
     For example, during the start-up of the engine at a low cooling water temperature, the main passage is blocked to allow the cooling water to return to the engine as it is from the bypass passage without passing through the radiator, thereby accelerating the warm-up of the engine. In addition, for example, in order to control the temperature of the cooling water to optimize the combustion of a fuel in the engine even after the warm-up, opening and closing (the opening degree) of the cooling water control valve is adjusted. 
     In the cooling water control valve, the use of a rotary valve or the like is considered. 
     In the rotary valve, for example, a flow passage is provided in a rotor, and in a housing which accommodates the rotor, an opening which is connected to an external flow passage and communicates with the flow passage in the rotor in a case where the angle of the rotor is an angle at which the rotor is opened is formed. 
     In addition, a seal is disposed between the opening of the housing and an opening of the flow passage of the rotor such that distribution of flowing water can be efficiently performed even when there is a gap between the openings. 
     For example, a structure in which a large gap is provided between the opening of the housing and the opening of the rotor and a packing is disposed therebetween is suggested (for example, refer to Patent Literature 1). 
     The packing is formed in a cylindrical shape in which both ends are open, one end portion serves as a seal for the opening of the rotor, and the other open end serves as a seal for the opening of the housing. In Patent Literature 1, the outer circumferential surface of the rotor and the inner circumferential surface of a part of the housing that accommodates the rotor are formed in cylindrical shapes, and the distance between the seal on the housing side and the seal on the rotor side is substantially constant at any position along the circumferential direction of the openings of the housing and the rotor. 
     Note that, for example, in a case where the inner surface which is provided with the opening on the housing side and opposes the rotor is a flat surface, the seal on the housing side has a flat surface shape, and the seal on the rotor side has a cylindrical surface shape. For this reason, the distance between the seals varies depending on the position in the circumferential direction. In this case, the length of a rubber as the packing disposed between the seals varies, and thus surface pressure applied to the seal from a surface that abuts on the seal varies with position. Therefore, there is concern that the function of the seal may not be sufficiently exhibited. As described above, by causing the distance between the seals to rarely change with position, the surface pressure can be allowed to be substantially constant even at different positions in the circumferential direction of the seal. 
     PATENT LITERATURE 
     Patent Literature 1: Japanese Publication No. 2000-193104 A 
     SUMMARY 
     In a case where sealing is performed only by an elastic force based on compression of a rubber-like seal member body, for example, the use of a hard rubber-like member is considered. However, in this case, there is a problem of followability due to a small displacement, or there is a problem in that the rotation of the rotor is stopped when foreign matter becomes stuck or the like. In combination with the seal member, for example, it may be preferable to use a spring, and for example, it may be preferable to use a coil spring, a wave washer, or the like by which a certain degree of displacement is expected. 
     However, when the seal parts of the rotor and the housing have complex structures due to the spring, the cost of the rotary valve is increased, and an assembly operation becomes complex. 
     Therefore, a seal member which is a single member that realizes members having a plurality of functions needed to enable a reduction in cost and an efficient assembly operation with a structure that enables efficient distribution of flowing water is required. 
     In addition, in consideration of positioning and holding of the seal member, it may be preferable to dispose a cylindrical member that supports the seal on the housing side, and in consideration of assembly, it may be preferable that a cylindrical nipple or the like that supports a cylindrical tool member be inserted into a part of the housing to which an external pipe is connected. 
     However, the contact part (tip end part) of the seal member which comes into contact with the rotor has a cylindrical surface shape, and the shape (a height from a base end portion when the base end portion is in one plane) varies depending on the position in the circumferential direction. In this case, for example, when the nipple is inserted into the seal member and thus the seal member is fixed, when a tip end surface having a shape corresponding to the above-mentioned cylindrical outer circumferential surface of the seal member is not correctly disposed on the cylindrical outer circumferential surface of the rotor, that is, when a positional shift occurs in the circumferential direction, there is concern that a high surface pressure and a low surface pressure occur on a contact surface between the rotor and the seal member and a function as a seal is insufficient. 
     In addition, when the seal member is moved in the circumferential direction during use, the same problem occurs. 
     Various embodiments have been made taking the forgoing circumstances into consideration, and a purpose thereof is to provide a rotary valve that uses a seal member having a shape in which a plurality of functions is integrated and can prevent a positional shift in a circumferential direction of the seal member. 
     In order to achieve the object described above, a rotary valve of the present invention includes: 
     a rotor which is rotated to open and close a flow passage; and a casing which accommodates the rotor, 
     wherein a rotor opening which is a part of a passage of a fluid is formed in a cylindrical outer circumferential surface of the rotor, 
     a rotor accommodating space which rotatably accommodates the rotor is formed in the casing, 
     a casing opening which is a passage of the fluid when communicating with the rotor opening is formed in an inner surface of the rotor accommodating space of the casing that faces the rotor, 
     a cylindrical seal member which extends to abut on the outer circumferential surface of the rotor including the rotor opening, and a positioning portion which determines an angular position around an axis of the seal member are provided in the casing opening, 
     the cylindrical seal member includes a cylindrical body portion in which a tip end shape on the rotor side is a shape along the outer circumferential surface of the rotor, a tip end abutting portion which is provided in a tip end portion of the body portion on the rotor side to be integrated with the body portion toward the outer circumferential surface of the rotor and abuts on the outer circumferential surface of the rotor, and a rotation stopping portion which is engaged with the positioning portion of the casing opening to regulate a rotation around the axis of the seal member and to determine the angular position around the axis of the seal member, 
     the tip end abutting portion has a cylindrical shape and has a shape that is curved along the outer circumferential surface of the rotor, 
     the tip end abutting portion includes an inwardly curved portion which is narrowed inwardly toward a tip end side and is curved to be folded back and/or an outwardly curved portion which is widened outwardly toward the tip end side and is curved to be folded back, and 
     the seal member is disposed so that the inwardly curved portion and/or the outwardly curved portion is pressed against the outer circumferential surface of the rotor. 
     According to this configuration, the tip end abutting portion of the seal member includes the inwardly curved portion which is narrowed inwardly and is curved to be folded back and/or the outwardly curved portion which is widened outwardly and is curved to be folded back, and the inwardly curved portion and/or the outwardly curved portion functions as a seal which abuts on the rotor and also functions as a spring. 
     That is, the inwardly curved portion and/or the outwardly curved portion has a shape in which, for example, an elastic force is not applied by a rubber-like resin as a lump, but for example, a biasing force is easily applied by equivalent elastic deformation as that of a leaf spring or the like. That is, since the cross-section thereof has a shape that is bent and folded back, in a case where a pressing force is applied, a part closer to the base end side than the contact position that comes into contact with the rotor in the direction intersecting the pressing direction functions as a spring. In addition, the apex part of the folded part comes into contact with the outer circumferential surface of the rotor, and thus sealing characteristics can be easily secured compared to a case where the tip end comes into contact therewith. 
     The shape of the inwardly curved portion and/or the outwardly curved portion along the circumferential direction is the same curved shape as the rotor opening, and even when the rotor opening has a shape along the cylindrical surface, the inwardly curved portion and/or the outwardly curved portion which functions as a spring also has the same cylindrical surface shape such that an elastic force is less likely to change with position. 
     In addition, it may be preferable that the end surface of the body portion of the seal member on the base end side thereof have a shape which comes into contact with the member on the casing side, and the tip end abutting portion of the inwardly curved portion and/or the outwardly curved portion as a spring is pressed against the outer circumferential surface of the rotor and receives a reaction force from the member on the casing side to be supported. In addition, in a case where a seal is also needed on the casing side, the base end of the body portion of the inwardly curved portion and/or the outwardly curved portion as a spring is pressed against the member on the casing side and thus can function as the seal. 
     Since the tip end abutting portion (inwardly curved portion and/or outwardly curved portion) of the seal member has a shape along the cylindrical outer circumferential surface, when the angular position is shifted in a rotation around the axis of the seal member, the surface pressure applied to the contact part between the rotor and the seal member varies depending on the position in the circumferential direction of the seal member to cause deterioration in a seal function. However, it is possible to perform the positioning of the angle around the axis and to prevent the shift of the angular position, using the rotation stopping portion of the seal member engaged with the positioning portion of the casing opening. 
     In the above configuration of the present invention, it may be preferable that the casing opening is formed in the casing to have a cylindrical shape, a cylindrical support cylindrical portion which supports the seal member is inserted into the casing opening in a state of being inserted into the body portion of the seal member, the positioning portion has a groove-like or rib-like shape and is provided on the inner circumferential surface of the casing opening along the axial direction of the casing opening, and the rotation stopping portion engaged with the positioning portion has a rib-like or groove-like shape and is provided on the outer circumferential surface of the seal member. 
     According to such a configuration, the rib is inserted into the groove, and thus the angular position around the seal member can be determined with respect to the casing opening and the shift of the angular position can be prevented. Thus, the tip end abutting portion of the seal member can be positioned at a correct angle with respect to the outer circumferential surface of the rotor to prevent the seal part of the seal member from being in a different surface pressure state depending on the position in the circumferential direction and to suppress the deterioration in the seal function. 
     A seal for a rotary valve that includes a rotor and a casing having a rotor accommodating space to accommodate the rotor, the rotor accommodating space having a casing opening with one or more positioning portions formed in an inner circumferential surface thereof. The seal includes a seal member that is provided in the casing opening of the rotor accommodating space, the seal member including one or more rotation stopping portions disposed on an outer circumferential surface thereof, the one or more rotation stopping portions being configured to be inserted into the one or more positioning portions formed in the inner circumferential surface of the casing opening. 
     According to various embodiments, one seal member can have a seal function and a spring function to be required, so that a spring is not required as a separate member and the reduction in cost and the efficiency of an assembly operation can be achieved. Moreover, the seal member can be positioned and held in a correct angular position around the axis thereof, so that the seal function can be further reliably obtained. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       These and/or other aspects and advantages will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a perspective view illustrating a rotary valve of an embodiment; 
         FIG. 2  is a perspective view illustrating the rotary valve; 
         FIG. 3  is a partially cutaway perspective view illustrating the rotary valve; 
         FIG. 4  is a main part cross-sectional view illustrating the rotary valve; 
         FIG. 5  is a main part cross-sectional view illustrating a casing of the rotary valve; 
         FIG. 6  is a cross-sectional view illustrating a seal member of the rotary valve; 
         FIG. 7  is a main part cross-sectional view illustrating a connection member of a support cylindrical portion of the rotary valve; 
         FIG. 8  is a plane view illustrating the seal member; 
         FIG. 9  is a partial cross-sectional view illustrating the seal member; 
         FIG. 10  is a main part side view illustrating a casing opening of the casing; 
         FIG. 11  is a main part cross-sectional view illustrating an inwardly curved portion as a tip end abutting portion of the seal member; 
         FIG. 12  is a main part cross-sectional view illustrating an outwardly curved portion as the tip end abutting portion of the seal member; 
         FIG. 13  is a main part cross-sectional view illustrating the inwardly curved portion and the outwardly curved portion as the tip end abutting portion of the seal member. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
     A rotary valve of this embodiment is used, for example, to control cooling water of the engine of a vehicle, and in an engine cooling system which includes a main flow passage that is mounted on an engine block of the engine to circulate the cooling water between the engine block and a radiator, a sub-flow passage which supplies the cooling water to a device (for example, a heater or a throttle) that needs temperature adjustment using the cooling water, and a bypass flow passage that bypasses the radiator, the rotary valve is used to open and close the main flow passage and the sub-flow passage. 
     As illustrated in  FIGS. 1 to 3 , a rotor  1  (illustrated in  FIG. 3 ), a casing  2  which rotatably accommodates the rotor  1 , a rotation driving device  3  (illustrated as an external form covered by casings  3   a  and  3   b  for the rotation driving device  3 ) which drives the rotor  1  to rotate, a main connection member  5  which includes a main connection pipe  4  that is connected to the main flow passage and causes the cooling water (fluid) to flow out (or flow in), and a sub-connection member  7  which includes a sub-connection pipe  6  that is connected to the sub-flow passage and causes the cooling water to flow out (or flow in) are provided. 
     The rotor  1  includes a cylindrical rotating shaft  11  which is thin and long, a cylindrical portion  12  which is formed in a thick cylindrical shape centered on the rotating shaft  11 , and spoke portions  13  which have shapes that extend in four directions from the rotating shaft  11  along the radial direction of the cylindrical portion  12  at both end portions of the cylindrical portion  12  in the axial direction thereof and are connected to the cylindrical portion  12 . 
     Right and left end surface parts of the rotor  1  are formed as the spoke portions  13  which have shapes that extend from the above-described rotating shaft  11  in the four directions, and thus there are openings between the parts that extend in the four directions. Therefore, four openings (end surface side openings)  14  are respectively provided in the right and left end surfaces of the rotor  1 , and the area occupied by the openings  14  is larger than the area occupied by the spoke portions  13  at the end surfaces of the rotor  1 . 
     In addition, the end portions of the rotating shaft  11  respectively protrude from both the end surfaces of the rotor  1 . 
     In the outer circumferential surface of the rotor  1  (the cylindrical portion  12 ), a rotor opening  15  having a circumferential length of substantially the half (slightly shorter than the half) of the outer circumferential surface is provided. Both the end portions of the rotor opening  15  in the circumferential direction are formed in a semicircular shape. In addition, the length of the width of the rotor opening  15  along the axial direction of the rotor  1  is equal to or longer than the half of the length of the rotor  1  along the axial direction, and for example, equal to or longer than two thirds thereof. 
     The rotor opening  15  of the outer circumferential surface of the rotor  1  is provided in the cylindrical portion  12  of the rotor  1 , and penetrates through the cylindrical portion  12  so that the inside and the outside of the rotor  1  (the cylindrical portion  12 ) communicate with each other. 
     A part of the outer circumferential surface of the rotor  1  (cylindrical portion  12 ) excluding the rotor opening  15  is a rotor outer circumference blocking surface  16  which is an outer circumferential surface with no opening. Here, the length of the rotor opening  15  along the circumferential direction of the outer circumferential surface of the rotor  1  is substantially the half of the length of the entire circumference, and the length of the rotor outer circumference blocking surface  16  with no opening is substantially the half of the length along the circumferential direction of the outer circumferential surface of the rotor  1 . 
     The casing  2  is formed substantially in a hexahedron (rectangular parallelepiped) box shape, and a rotor accommodating space  2   a  (illustrated in  FIG. 3 ) which rotatably accommodates the rotor  1  is formed inside the casing  2 . Two surfaces among the six surfaces of the casing  2  which oppose each other have inner surfaces that oppose the end surfaces of the rotor  1 , and the other four surfaces have inner surfaces that oppose the outer circumferential surface of the rotor. Here, plate-like parts which respectively form the surfaces of the hexahedron are referred to as a first plate-like portion  21  to a sixth plate-like portion  26 . 
     The plate-like parts having inner surfaces that oppose the end surfaces of the rotor  1  are referred to as the first plate-like portion  21  and the second plate-like portion  22 , and the plate-like parts having inner surfaces that oppose the outer circumferential surface of the rotor  1  are referred to as the third plate-like portion  23  to the sixth plate-like portion  26 . 
     The rotation driving device  3  is mounted on the first plate-like portion  21  which is one of the first plate-like portion  21  and the second plate-like portion  22 . A hole into which the rotor  1  can be inserted is provided in the first plate-like portion  21 . The hole is blocked by a lid member (not illustrated). The driving shaft of the rotation driving device  3  passes through the lid member in a state of being sealed, and is connected to the rotor  1  to drive the rotor  1  to rotate. 
     The rotation driving device  3  is provided with, for example, a motor which rotates the driving shaft therein. The driving shaft is connected to the motor via a decelerator. The driving shaft is connected to one end portion of the rotating shaft  11  of the rotor  1 . The other end portion of the rotating shaft  11  is rotatably supported by a bearing portion (not illustrated) of the second plate-like portion  22 . 
     The third plate-like portion  23  of which the inner surface opposes the outer circumferential surface of the rotor  1  is provided so that the outer circumferential part thereof extends outward in a flange shape to serve as a flange portion  23   b,  and a part surrounded by the first plate-like portion  21 , the second plate-like portion  22 , the fourth plate-like portion  24 , and the sixth plate-like portion  26  is an opening. 
     The flange portion  23   b  is mounted at a mounting position having an opening of the engine block of the engine via a connection member  33 . The connection member  33  is a cylindrical member in which a flange portion  34  which is connected to the flange portion  23   b  is provided on the opening side of one end portion thereof and a flange portion  35  which is connected to the engine block is provided on the other opening side. The rotary valve is connected to the engine block via the connection member  33 . 
     The third plate-like portion  23  to which the connection member  33  is connected is provided with the opening as described above so that the cooling water can flow into the opening from the engine block side via the connection member  33 . Note that, a configuration may also be employed in which the cooling water flows out to the engine block side. 
     The sub-connection member  7  described above is mounted on the outer surface of the fifth plate-like portion  25 . The fifth plate-like portion  25  is provided with an opening (casing opening)  25   a  which communicates with the sub-connection pipe  6  of the sub-connection member  7 . 
     The opening  25   a  is the opening  25   a  on the outflow side (may also be the inflow side) at which the cooling water flows out from the rotary valve to the outside. For example, the cooling water which flows out from the opening  25   a  is circulated through the sub-flow passage (for example, including a heater or the like), and is returned to the engine block from a pump. 
     The fifth plate-like portion  25  is disposed to oppose and is substantially parallel to the third plate-like portion  23  having an opening  23   a  on an inflow side (may also be an outflow side) and is disposed to be substantially perpendicular to the sixth plate-like portion  26  and the fourth plate-like portion  24 . 
     The opening  25   a  has a cylindrical inner circumferential surface. In addition, as illustrated in  FIG. 4 ,  FIG. 5 , and  FIG. 10 , a pair of groove-like positioning portions  28  is provided on the inner circumferential surface of the opening  25   a  to extend in an axial direction thereof. The positioning portion  28  is positioned to be in parallel with a direction orthogonal to the axial direction of the rotor  1  and to intersect with the cylindrical inner circumferential surface on a line passing the central axis (orthogonal to the central axis) of the opening  25   a  having the cylindrical inner circumferential surface. 
     In addition, the cylindrical opening  25   a  is configured such that an inner diameter of the tip end side (sub-connection member  7  side) thereof is larger than that of the base-end side (rotor  1  side) thereof. The groove-like positioning portion  28  is provided at the base-end side having the inner diameter of the inner circumferential surface of the opening  25   a  narrower than that of the tip end side. 
     The sub-connection member  7  includes a plate-like connection portion  71 , and a support cylindrical portion  72  having a cylindrical shape that extends from the connection portion  71  in a state of being inserted into the opening  25   a.  A through-hole is formed in the connection portion  71  of the sub-connection member  7 , and the through-hole communicates with the inside of the support cylindrical portion  72  on the inner surface side of the connection portion  71  and communicates with the inside of the sub-connection pipe  6  on the outer surface side. Accordingly, the support cylindrical portion  72  and the sub-connection pipe  6  communicate with each other. 
     A tip shape of the support cylindrical portion  71  has a curved shape along the cylindrical outer circumferential surface. 
     Furthermore, as illustrated in  FIGS. 4 and 7 , the support cylindrical portion  72  is configured such that a diameter of the base end portion is slightly larger than that of the tip end portion in accordance that a diameter of the tip end portion of the opening  25   a  in the casing  2  is slightly larger than that of the base end portion. Note that, a direction of the tip end side of the support cylindrical portion  72  is reverse to a direction of the tip end side of the cylindrical opening  25   a.    
     In addition, the inner surface of the connection portion  71  comes into surface contact with the side surface of the outside of the opening  25   a  of the fifth plate-like portion  25  such that the opening  25   a  is in a state of being blocked in a state where the sub-connection member  7  is connected to the casing  2 . However, the opening  25   a  communicates with the sub-connection pipe  6  via the support cylindrical portion  72 . 
     An annular support groove  73  is formed on the outer circumferential side of the support cylindrical portion  72  of the connection portion  71 . 
     The inner diameter of the cylindrical opening  25   a  and the outer diameter of the annular support groove  73  are substantially equal to each other. The inner diameter of the support groove  73  and the outer diameter of the support cylindrical portion  72  are substantially equal to each other. The outer diameter of the support cylindrical portion  72  is narrower than the inner diameter of the opening  25   a.  In addition, the opening  25   a,  the support cylindrical portion  72 , and the support groove  73  are disposed on substantially the same axis. 
     Note that, as illustrated in a schematic cross-sectional view of  FIG. 4 , instead of providing the support groove  73 , an annular protrusion  75  may be provided in the sub-connection member  7 . The outer diameter of the annular protrusion  75  is substantially equal to the inner diameter of the opening  25   a  so as to be inserted into the opening  25   a.  The inner diameter of the protrusion  75  is equal to the outer diameter of the support cylindrical portion  72 . 
     Note that, as illustrated in  FIG. 7 , the annular support groove  43  or the annular protrusion  75  may not be provided around the support cylindrical portion  72  of the sub-connection member  7 . 
     A cylindrical seal member  77  is provided in the support cylindrical portion  72  so as to cover the outer circumference thereof. That is, the support cylindrical portion  72  is inserted into the cylindrical seal member  77 . The seal member  77  is, for example, a rubber or resin member, and is made of a resin member having a relatively low coefficient of friction. The inner diameter of the seal member  77  is equal to or slightly narrower than the outer diameter of the support cylindrical portion  72 , and the support cylindrical portion  72  is inserted into the seal member  77  in a state in which the seal member  77  is elastically deformed such that the diameter thereof is enlarged. In addition, as illustrated in  FIGS. 4 ,  6 , and  9 , the inner diameter and the outer diameter of the seal member become wider at the tip end side relative to the base-end side in accordance that the outer diameter of the base-end side of the support cylindrical portion  72  is larger than that of the tip end side and the inner diameter of the tip end side of the cylindrical opening  25   a  is larger than that of the base-end side. 
     As illustrated in  FIGS. 4 ,  6 , and  9 , the seal member  77  is provided with a cylindrical body portion  78 , a circumferential surface seal portion  79  having a wall thickness provided on the base end portion of the body portion  78 , and a tip end abutting portion  80  provided on the tip end portion. With respect to the tip end abutting portion  80  and the body portion  78  (excluding the circumferential surface seal portion  79 ), the inner diameter and the outer diameter of the circumferential surface seal portion  79  become larger. 
     The seal member  77  is disposed so that the end surface of the base end portion thereof abuts on the bottom surface of the support groove  73 . As illustrated in  FIG. 4 , in a case where the protrusion  75  is provided, the end surface of the base end portion of the seal member  77  abuts on the protrusion  75 . 
     In addition, as the circumferential surface seal portion  79 , three protrusions (in three stages) which are formed along the circumferential direction are provided in the base end portion along the axial direction. The cross-section of the protrusion has a substantially arc shape which expands toward the outer circumferential side. The wall thickness (thickness) of the circumferential surface seal portion  79  at the apex of the protrusion of the circumferential surface seal portion  79  is longer than the length of the half of the difference between the inner diameter and the outer diameter of the support groove  73 . 
     The wall thickness (thickness) at the apex of the protrusion of the circumferential surface seal portion  79  is longer than the length of the half of the difference between the outer diameter of the support cylindrical portion  72  and the inner diameter of the opening  25   a  of the fifth plate-like portion  25  of the casing  2 . 
     Here, a part which is disposed inside the support groove  73  of the circumferential surface seal portion  79  and a part which is disposed between the outer circumferential surface of the support cylindrical portion  72  and the inner circumferential surface of the opening  25   a  are elastically deformed to respectively correspond to the intervals thereof. 
     The end surface of the body portion  78  on the base end portion (including the circumferential surface seal portion  79 ) side is disposed on a single plane along the bottom surface of the support groove  73 . The shape of the tip end portion of the body portion  78  that faces the rotor  1  side is a shape that is curved along the cylindrical surface. That is, the shape is a linear shape in a direction along the axial direction of the rotor  1  and is a circumferential shape in a direction along the circumferential direction, which follows the cylindrical surface. The shape of the tip end of the body portion  78  is the same as the shape of the tip end of the support cylindrical portion  72 . 
     In this embodiment, the tip end abutting portion  80  is an inwardly curved portion  81  which is formed to extend from the tip end of the body portion  78  toward the rotor  1 , is narrowed inwardly toward the tip end side, and is curved to be folded back. The diameter of the inwardly curved portion  81  is reduced toward the tip end side. In addition, since the inwardly curved portion  81  is curved to be folded back, the cross-sectional shape thereof is a fishhook shape with no barb. 
     Moreover, the thickness of the tip end side of the inwardly curved portion  81  is smaller than that on the base end side thereof. In addition, the inwardly curved portion  81  has a curved shape which is substantially the same as a shape which draws a circle on the above-described cylindrical surface of the tip end portion of the body portion  78 , and is disposed between the tip end of the body portion  78  and the outer circumferential surface of the rotor  1 . Therefore, in a state where the inwardly curved portion  81  abuts on the outer circumferential surface of the rotor  1 , the abutting part thereof has a shape along the cylindrical surface. 
     The part of the inwardly curved portion  81  which comes into contact with the outer circumferential surface of the rotor  1  is not the tip end which is folded back to face the opposite side to the rotor  1 , and a part which faces the outer circumferential surface of the rotor  1  in the curved portion between the tip end and the base end of the inwardly curved portion  81  comes into contact with the rotor  1 . In addition, the part of the inwardly curved portion  81  which comes into contact with the rotor  1  is a part that is already thinned from the body portion  78 . 
     That is, the thickness of the base end of the inwardly curved portion  81  is substantially the same as that of the body portion  78 , and is narrowed toward the tip end. However, the thickness of a part from the position slightly closer to the base end side than the part that comes into contact with the rotor  1  to the tip end is a substantially constant thickness, and this part is the thinnest state. 
     The inwardly curved portion  81  functions as a spring when elastically deformed due to this shape, and the spring is in a state of being elastically deformed by being pressed against the outer circumferential surface of the rotor  1 . The tip end side of the inwardly curved portion  81  (the tip end abutting portion  80 ) has a shape that is curved along the cylindrical surface to correspond to the outer circumferential surface of the rotor  1 , and as the tip end portion of the body portion  78  has a shape that is curved along the cylindrical surface as described above, the base end portion of the inwardly curved portion  81  has a shape that is curved along the cylindrical surface. 
     The distance between the part of the inwardly curved portion  81  that abuts on the rotor  1  and the base end portion thereof is constant regardless of position in the circumferential direction. That is, the axial direction of the cylindrical surface shape which is the shape of the inwardly curved portion  81  on the tip end side thereof and the axial direction of the cylindrical surface shape which is the shape on the base end side thereof are disposed to be parallel to each other, and the tip end side and the rear end side of the inwardly curved portion  81  are in a state of following the surface in the same direction as the cylindrical surface. In addition, the shape of the tip end portion of the support cylindrical portion  72  is also substantially the same as the tip end shape of the body portion  78 , and the inwardly curved portion  81  is disposed closer to the tip end side than the support cylindrical portion  72 . 
     In addition, the cylindrical inwardly curved portion  81  has a structure which comes into contact with the rotor  1  over the entire circumference. Therefore, in a state where the inwardly curved portion  81  comes into contact with the rotor outer circumference blocking surface  16  of the rotor  1 , the tip end side opening of the cylindrical seal member  77  is in a state of being completely blocked. At this time, the support cylindrical portion  72  is in a state of being blocked, and the sub-connection pipe  6  is in a state of being blocked. 
     In a case where the rotor opening  15  and the inwardly curved portion  81  overlap each other, the valve is in a state of being opened, and the cooling water that flows from the opening of the third plate-like portion  23  can be in a state of flowing out from the engine block side to a sub-passage side via the internal space of the rotor  1 . Note that, a configuration may also be employed in which the inflow and outflow of the cooling water are switched. 
     Note that, the opening degree of the valve is adjusted by a ratio at which the rotor opening  15  and the inwardly curved portion  81  overlap, thereby adjusting a flow rate. 
     The rotor opening  15  is formed such that an opening for a sub-passage and an opening for a main passage to be described are fitted and integrated with each other in a circumferential direction, and a length of the rotor opening  15  along the circumferential direction of the rotor  1  becomes longer than a diameter of a part at which the inwardly curved portion  81  comes in contact with the rotor  1 . 
     A pair of rib-like rotation stopping portions  85  is provided on the outer circumferential surface of the body portion  78  of the seal member  77  so as to correspond to the groove-like positioning portions  28  of the opening  25   a  of the casing  2 . The rib-like rotation stopping portions  85  are provided along the axial direction of the cylindrical seal member  77  and are provided at a part which protrudes to the most tip end side of the tip end abutting portion  80  (inwardly curved portion  81 ). 
     That is, the rotation stopping portion  85  is provided at two points at which the tip end abutting portions  80  are disposed to be farthest from each other and on the outer circumferential surface of the body portion  78  corresponding to two points corresponding to apex parts. The rotation stopping portion  85  can be inserted into the pair of groove-like positioning portions  28  formed on the inner circumferential surface of the cylindrical opening  25   a  of the casing  2 . 
     When the rib-like rotation stopping portions  85  of the seal members  77  are inserted into the groove-like positioning portions  28  formed on the inner circumferential surface of the opening  25   a  of the casing  2 , an angular position around the axis of the seal member  77  is correct with respect to the rotor  1 , and thus it is possible to make a state in which the same surface pressure is applied to any position in the circumferential direction of the contact part on which the tip end abutting portion  80  (inwardly curved portion  81 ) comes in contact with the rotor  1 . 
     That is, the inwardly curved portion  81  (tip end abutting portion  81 ) functions as a spring and is pressed against the outer circumferential surface of the rotor  1 , but the surface pressure generated between the outer circumferential surface of the rotor  1  and the tip end abutting portion  81  by the biasing force of the spring varies depending on the position in the circumferential direction to cause the deterioration in the seal function when the angular position around the axis of the seal member  77  is not correctly positioned. On the other hand, the angular position of the seal member  77  can be correctly adjusted by the above-mentioned positioning portion  28  and the rotation stopping portion  85  to improve the seal function. 
     The above-mentioned main connection member  5  is mounted on the outer surface of the sixth plate-like portion  26 . The sixth plate-like portion  26  is provided with an opening (casing opening)  26   a  which communicates with the main connection pipe  4  of the main connection member  5 . 
     The opening  26   a  is the opening  26   a  on the outflow side (may also be inflow side) through which the cooling water flows out from the rotary valve to the outside. For example, the cooling water which flows out from the opening  26   a  is circulated through the main flow passage. The cooling water is returned to the engine block from the pump via the radiator. 
     The sixth plate-like portion  26  is disposed to be substantially perpendicular to the third plate-like portion  23  having the opening  23   a  on the inflow side (may also be the outflow side) and the fifth plate-like portion  25 . 
     The opening  26   a  has a cylindrical inner circumferential surface. In addition, even though not illustrated, the positioning portion  28  is provided on the inner circumferential surface of the opening  26   a  as in the opening  25   a.    
     The main connection member  5  includes a plate-like connection portion  51 , and a support cylindrical portion  52  having a cylindrical shape that extends from the connection portion  51  in a state of being inserted into the opening  26   a.  A through-hole is formed in the connection portion  51  of the main connection member  5 , and the through-hole communicates with the inside of the support cylindrical portion  52  on the inner surface side of the connection portion  51  and communicates with the inside of the main connection pipe  4  on the outer surface side. Accordingly, the support cylindrical portion  52  and the main connection pipe  4  communicate with each other. 
     In addition, the inner surface of the connection portion  51  comes into surface contact with the side surface of the outside of the opening  26   a  of the sixth plate-like portion  26  such that the opening  26   a  is in a state of being blocked in a state where the main connection member  5  is connected to the casing  2 . However, the opening  26   a  communicates with the sub-connection pipe  6  via the support cylindrical portion  52 . 
     An annular support groove  53  is formed on the outer circumferential side of the support cylindrical portion  52  of the connection portion  51 . 
     The inner diameter of the cylindrical opening  26   a  and the outer diameter of the cylindrical support groove  53  are substantially equal to each other. The inner diameter of the support groove  53  and the outer diameter of the support cylindrical portion  52  are substantially equal to each other. The outer diameter of the support cylindrical portion  52  is narrower than the inner diameter of the opening  26   a.  In addition, the opening  26   a,  the support cylindrical portion  52 , and the support groove  53  are disposed on substantially the same axis. 
     Similarly to the case of the sub-connection member  7 , instead of providing the support groove  53 , an annular protrusion may be provided. The sub-connection member  7  and the main connection member  5  have different structures in the sub-connection pipe  6  and the main connection pipe  4  provided therein. However, since the shapes of the connection portions  51  and  71  on the inner surface sides are substantially the same, the support cylindrical portion  72  and the support cylindrical portion  52  have the same shape, and the support groove  73  and the support groove  53  have the same shape. 
     The cylindrical seal member  77  is provided in the support cylindrical portion  52  to cover the outer circumference thereof. That is, the support cylindrical portion  52  is inserted into the cylindrical seal member  77 . The seal member  77  is similar to the seal member  77  on the above-mentioned sub-connection member  7  side, which has the similar shape and the similar function. That is, as described above, the seal member  77  includes the body portion  78 , the circumferential surface seal portion  79 , the tip end abutting portion  80  (inwardly curved portion  81 ), and the rotation stopping portion  85 . 
     According to the above-described seal member  77 , the base end portion sides seal the openings  25   a  and  26   a  of the casing  2  with the circumferential surface seal portions  79 . Basically, the circumferential surface seal portions  79  on the base end portion sides of the body portions  78  of the seal members  77  cover and seal between the inner circumferential surfaces of the openings  25   a  and  26   a  and the support cylindrical portions  52  and  72  which are respectively inserted into the openings  25   a  and  26   a.    
     That is, the circumferential surface seal portions  79  which protrude from the outer circumferential surface sides of the base end portions of the seal members  77  in the three stages are in a state where the thicknesses thereof between the inner circumferential surfaces of the openings  25   a  and  26   a  and the support cylindrical portions  52  and  72  are compressed, and the cooling water is sealed by this part. That is, the circumferential surface seal portion  79  functions as a seal ring. 
     In a state where the tip end portion of the seal member  77  is pressed against the outer circumferential surface of the rotor  1 , the inwardly curved portion  81  of the tip end abutting portion  80  functions as a spring such that a sealed state is achieved in a state where the tip end of the seal members  77  is pressed against the rotor  1 . 
     In this case, the inwardly curved portion  81  is not simply compressed as a rubber-like elastic member but undergoes bending deformation to function as the spring. Accordingly, compressive stress, tensile stress, and shearing stress occur due to the bending. 
     Therefore, the tip end abutting portion  80  can obtain a relatively large basing force as the spring, and has a large elastic deformation amount. 
     By the basing force of the inwardly curved portion  81  as the spring, the infiltration of foreign matter between the seal member  77  and the rotor  1  is prevented. In a case where the foreign matter is infiltrated, the member for sealing can be significantly deformed and thus the foreign matter is easily removed. In addition, the end surface of the seal member  77  on the base end portion side is pressed against the sub-connection member  7  (the main connection member  5 ) by the biasing force of the inwardly curved portion  81  which functions as the spring, thereby proving a sealing function. Due to the followability of the spring with respect to the outer circumferential surface of the rotor  1  and the like, a heavy load is not applied to the rotation of the rotor  1 , and for example, a low frictional material such as polytetrafluoroethylene is not needed for the part which abuts on and slides with the rotor  1 . Here, it is preferably to use a material having a coefficient of friction as low as possible. 
     The seal member  77  which is a single member and includes the circumferential surface seal portions  79  that functions as the seal ring on the base end portion side as described above and the tip end abutting portion  80  (the inwardly curved portion  81 ) which functions as the seal that abuts on the rotor  1  and functions as the spring. That is, the single member can realize at least three functions. Note that, it may be preferable that as the rubber or resin material used in the seal member  77 , those having a coefficient of friction as low as possible be selected among rubber or resin materials having the performance for functioning as the seal ring, the seal, and the spring described above. 
     In addition, due to the positioning portion  28  of the casing  2  and the rotation stopping portion  85  of the seal member  77  as described above, the seal member  77  is disposed at a correct angular position, and thus biasing force of the seal member  77  functioning as the spring can be uniformly applied to the outer circumferential surface of the rotor  1 . 
     In this embodiment, as the tip end abutting portion  80 , for example, the inwardly curved portion  81  illustrated in  FIG. 11  is provided. However, an outwardly curved portion  82  illustrated in  FIG. 12  may also be provided. The outwardly curved portion  82  extends from the body portion  78  of the seal member  77  toward the rotor  1  and abuts on the outer circumferential surface of the rotor  1 . The outwardly curved portion  82  is widened outwardly toward the tip end side, and is curved to be folded back. The curved part between the base end portion and the tip end portion of the outwardly curved portion  82  comes into contact with the outer circumferential surface of the rotor  1 . 
     The outwardly curved portion  82  is curved outward, but functionally has the same functions as those the inwardly curved portion  81  and functions as the seal and the spring. In addition, for example, in a case where the cooling water flows from the rotor opening  15  side to the openings  25   a  and  26   a  of the casing, that is, in a case where a water pressure inside the rotor  1  is higher than that outside the rotor  1 , it may be preferable to use the above-described inwardly curved portion  81 , and higher seal performance than a case of using the outwardly curved portion  82  can be obtained. 
     Contrary to this, in a case where the cooling water flows from the openings  25   a  and  26   a  of the casing to the rotor opening  15 , that is, in a case where a water pressure outside the rotor  1  is higher than that inside the rotor  1 , it may be preferable to use the above-described outwardly curved portion  82 , and higher seal performance than a case of using the inwardly curved portion  81  can be obtained. 
     In addition, in a case where the direction of the water flow is changed, for example, as illustrated in  FIG. 13 , both the inwardly curved portion  81  and the outwardly curved portion  82  may be provided as the tip end abutting portion  80 . In this case, even when the water flow direction is changed, the seal performance can be prevented from being degraded. 
     DESCRIPTION OF REFERENCE CHARACTERS 
     
         
           1  rotor 
           2  casing 
           2   a  rotor accommodating space 
           15  rotor opening 
           25   a  casing opening 
           26   a  casing opening 
           28  positioning portion 
           77  seal member 
           78  body portion 
           79  circumferential surface seal portion 
           80  tip end abutting portion 
           81  inwardly curved portion 
           82  outwardly curved portion 
           85  rotation stopping portion