Patent Publication Number: US-11035287-B2

Title: Engine cooling structure

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The entire disclosure of Japanese Patent Application No. 2017-199632 filed on Oct. 13, 2017 including the specification, claims, drawings, and abstract is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     This specification discloses an engine cooling structure where an engine is cooled by a cooling fluid supplied from a radiator, and the cooling fluid discharged from the engine is cooled by the radiator. 
     BACKGROUND 
     An engine cooling structure is widely known where an engine is cooled by a cooling fluid supplied from a radiator, and the cooling fluid discharged from the engine is cooled by the radiator. In such a cooling structure, radiator hoses through which the cooling fluid flows extend between the radiator and the engine. 
     Such radiator hoses have a long length compared to a distance between the radiator and the engine. Accordingly, the radiator hose is liable to move significantly swinging at an intermediate portion of the radiator hose which is separated at a distance from fixed ends connected to the engine and the radiator. When the radiator hose swings significantly at the intermediate portion, there may be a case where the radiator hose interferes with other members so that the other members and/or the radiator hose deteriorate or are damaged. 
     In view of the above, fixing of the intermediate portion of the radiator hose to the engine by means of a fixing member is considered. With such a configuration, significant swinging of the intermediate portion of the radiator hose can be suppressed. 
     Conventionally, the intermediate portion of the radiator hose which is fixed to the engine is formed of a hose member having an outer surface made of ethylene-propylene rubber (EPDM) or the like. In this case, the hose member per se has vibration absorbing capability to some extent. Accordingly, even when the engine vibrates, the hose member fixed to the engine resists vibrating so that there is a low possibility of the hose member being damaged due to vibrations. 
     However, due to the arrangement relationship between the radiator hose and other members, there may be a case where a portion of the radiator hose which is fixed to the engine by means of the fixing member is not the hose member made of EPDM or the like, but is a connecting pipe connected to the hose member. Usually, such a connecting pipe is made of a resin or the like so that the connecting pipe is hard, thus having poor vibration absorbing characteristics in many cases. When such a connecting pipe is fixed to the engine by means of the fixing member, vibrations of the engine are transmitted to the connecting pipe through the fixing member so that the connecting pipe per se is liable to vibrate. Further, due to such vibrations, there is a possibility of loosening of the connection between the connecting pipe and the hose member, and of deterioration or damage of the connecting pipe per se. 
     JP 2017-115643 A (Patent literature 1) discloses a technique where pawls are formed on a peripheral edge of an intake duct through which air is introduced into an engine, and the pawls are fitted on a pin, projecting from a cylinder head cover, by way of a grommet made of a rubber material. According to such a technique, vibrations from a vehicle or the engine resist being transmitted to the intake duct. However, Patent literature 1 only relates to a mounting structure for an intake duct, and Patent literature 1 does not disclose a mounting structure for a radiator hose at all. 
     That is, conventionally, there has been no technique which can prevent a problem of a connecting pipe, caused by vibrations of an engine, in fixing a connecting pipe provided to a radiator hose to the engine. 
     Accordingly, this specification discloses an engine cooling structure which can fix a connecting pipe provided on a radiator hose to an engine while protecting the connecting pipe from vibrations of the engine. 
     SUMMARY OF THE INVENTION 
     An engine cooling structure disclosed in this specification is an engine cooling structure where an engine is cooled by a cooling fluid supplied from a radiator, and the cooling fluid discharged from the engine is cooled by the radiator. The engine cooling structure includes: a radiator hose having one end coupled to the engine, and having the other end coupled to the radiator, the radiator hose including two or more hose members and a connecting pipe configured to connect the two or more hose members to each other; and a clamp including a pipe-side connection portion connected to the connecting pipe, and an engine-side connection portion directly or indirectly connected to the engine. The clamp is provided with a transmission suppressing portion which suppresses transmission of vibrations from the engine-side connection portion to the connecting pipe. 
     With such a configuration, although the connecting pipe is fixed to the engine, the transmission suppressing portion is present so that vibrations of the engine transmitted to the engine-side connection portion resist being transmitted to the connecting pipe. As a result, it is possible to fix the connecting pipe to the engine while protecting the connecting pipe from vibrations of the engine. 
     The transmission suppressing portion may be formed of a gap provided between the pipe-side connection portion and the connecting pipe. 
     The transmission suppressing portion is formed of a gap so that it is possible to fix the connecting pipe to the engine while protecting the connecting pipe from vibrations of the engine with a simple structure. 
     In this case, the pipe-side connection portion may include an annular body  86  disposed on an outer periphery of the connecting pipe  38  with the gap  84 , which functions as the transmission suppressing portion  82 , interposed between the annular body  86  and the outer periphery of the connecting pipe  38 . 
     With such a configuration, the connecting pipe is movable in the circumferential direction, in the radial direction, and in the axial direction of the connecting pipe with respect to the pipe-side connection portion. As a result, vibrations in various directions resist being transmitted to the connecting pipe so that it is possible to more reliably protect the connecting pipe from vibrations of the engine. 
     Further, in this case, the connecting pipe may include a main tube, and a columnar portion which stands out from a peripheral surface of the main tube, and the pipe-side connection portion may have: the annular body disposed on the outer periphery of the main tube with the gap, which functions as the transmission suppressing portion, interposed between the annular body and the outer periphery of the main tube; and a center hole which is formed in a peripheral surface of the annular body, and into which the columnar portion is inserted. 
     With such a configuration, due to a contact relationship between the columnar portion and the center hole, an amount of movement of the connecting pipe in the circumferential direction and in the axial direction with respect to the pipe-side connection portion is limited to some extent. Accordingly, excessive movement of the connecting pipe can be restricted. 
     The transmission suppressing portion may be formed of a buffer member provided between the pipe-side connection portion and the connecting pipe. 
     When such a configuration is adopted, collision energy between the clamp and the connecting pipe is absorbed by the buffer member and hence, deterioration or damage of the clamp can be more reliably prevented. 
     According to the engine cooling structure disclosed in this specification, although the connecting pipe is fixed to the engine, the transmission suppressing portion is present so that vibrations of the engine transmitted to the engine-side connection portion resist being transmitted to the connecting pipe. As a result, it is possible to fix the connecting pipe to the engine while protecting the connecting pipe from vibrations of the engine. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Embodiments of the present disclosure will be described based on the following figures, wherein: 
         FIG. 1  is a schematic plan view of a front portion of a vehicle; 
         FIG. 2  is a perspective view of a connecting pipe; 
         FIG. 3  is a cross-sectional view of the connecting pipe; 
         FIG. 4  is a cross-sectional view taken along line A-A in  FIG. 3 ; 
         FIG. 5  is a view of a clamp in an open state as viewed in an axial direction; 
         FIG. 6  is a view of the clamp in a closed state as viewed in the axial direction; and 
         FIG. 7  is a plan view of the clamp. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an engine cooling structure for an engine  10  is described with reference to drawings.  FIG. 1  is a schematic plan view of a front portion of a vehicle. In  FIG. 1 , to easily distinguish between an inlet pipe  26  and an outlet pipe  28 , the outlet pipe  28  is illustrated with a larger diameter than the inlet pipe  26 . However, both pipes  26 ,  28  have the same diameter in the actual structure. In the same manner, an outlet hose  32  is also illustrated with a larger diameter than an inlet hose  30 . However, both hoses  30 ,  32  have the same diameter in the actual structure. Further, in  FIG. 1 , light shading is applied to the inlet hose  30 , and dark shading is applied to the outlet hose  32 . 
     This vehicle is a hybrid vehicle having the engine  10  and a motor as a power source for allowing the vehicle to travel. However, the technique disclosed in this specification is not limited to a hybrid vehicle, but may be also applicable to a vehicle having only the engine  10  as a power source. 
     As shown in  FIG. 1 , a space referred to as an engine compartment  100  is formed in the front portion of the vehicle. The engine  10  and a motor unit  14  are disposed in the vicinity of the center of the engine compartment  100 . The engine  10  is a water-cooled engine, and a water jacket (not shown in the drawing) forming a flow passage for a cooling fluid is provided in the engine  10 . The cooling fluid, for example, antifreeze, flows through the water jacket so that the engine  10  is cooled. One end of the flow passage formed of the water jacket forms an introduction port  22  for the cooling fluid, and the other end of the flow passage forms a discharge port  24  for the cooling fluid. The inlet pipe  26  and the outlet pipe  28  extend from an outer surface of the engine  10 . The inlet pipe  26  communicates with the introduction port  22 , and the outlet pipe  28  communicates with the discharge port  24 . 
     The motor unit  14  is disposed on the left side of the engine  10 . The motor unit  14  is configured such that a motor, a generator, a transmission and the like are formed into a unit. The motor generates power for traveling. The generator generates electric power using surplus power of the engine  10 . A power control unit  16  is also disposed in the vicinity of the motor unit  14  (for example, above the motor unit  14 ). An inverter, a transformer and the like are provided in the power control unit  16 . The inverter controls the drive of the motor and the generator. The transformer transforms input/output electric power. 
     A radiator  12  is disposed forward of the engine  10  and the motor unit  14 . The radiator  12  includes a radiator core  18  through which the cooling fluid discharged from the engine  10  flows. The cooling fluid is used for cooling the engine  10  so that the temperature of the cooling fluid is increased. Such a cooling fluid is cooled in the process of flowing through a flow passage formed in the radiator core  18 . The cooling fluid which is cooled is fed to the engine  10  again, and is used for cooling the engine  10 . 
     Radiator fans  20  which are electric fans are disposed rearward of the radiator core  18 . The radiator fans  20  are driven so as to feed air toward a rear portion of the vehicle. With such an operation, an amount of air flow which passes through the radiator core  18  is increased so that heat radiation from the cooling fluid is accelerated. A reservoir tank which stores the cooling fluid therein, a pump for pumping the cooling fluid and the like are also provided in the radiator core  18 . However, all of these members are well-known techniques and so detailed description of these members is omitted here. 
     The inlet hose  30  and the outlet hose  32  extend between the radiator core  18  and the engine  10  as radiator hoses through which a cooling fluid flows. One end of the inlet hose  30  is coupled to the inlet pipe  26 , and one end of the outlet hose  32  is coupled to the outlet pipe  28 . Further, the other end of the inlet hose  30  is coupled to a right end of the radiator core  18 , and the other end of the outlet hose  32  is coupled to a left end of the radiator core  18 . A cooling fluid cooled by the radiator core  18  is supplied to the water jacket for the engine  10  through the inlet hose  30  and the inlet pipe  26 . The cooling fluid supplied to the water jacket performs heat exchange with the engine  10 , thus cooling the engine  10 . The cooling fluid that has increased in temperature due to such heat exchange is returned to the radiator core  18  through the outlet pipe  28  and the outlet hose  32 . The cooling fluid returned to the radiator core  18  is cooled by air in the process of flowing through the radiator core  18 , and the cooling fluid is supplied to the engine  10  again. 
     The inlet hose  30  is roughly divided into an upstream hose  35  extending from the radiator  12 , a downstream hose  36  coupled to the inlet pipe  26 , and a connecting pipe  38  which connects the upstream hose  35  and the downstream hose  36  to each other. The connecting pipe  38  is a three-way pipe, as will be described later. Not only the upstream hose  35  and the downstream hose  36  but also a cooler hose  34  extending to an oil cooler (not shown in the drawing) are connected to the connecting pipe  38 . The upstream hose  35 , the downstream hose  36  and the cooler hose  34  are not particularly limited provided that the hoses have sufficient heat resistance and pressure resistance. For example, each hose may be formed using a hose where a reinforcing fiber layer is embedded in a tube body made of a rubber material such as ethylene-propylene rubber (EPDM). 
     The connecting pipe  38  is a hard pipe member made of a resin or the like.  FIG. 2  is a perspective view of the connecting pipe  38 .  FIG. 3  is a transverse cross-sectional view of the connecting pipe  38 , and  FIG. 4  is a cross-sectional view taken along line A-A in  FIG. 3 . As shown in  FIG. 3  and the like, the connecting pipe  38  has a three-way structure which includes a main tube  50  to which the upstream hose  35  and the downstream hose  36  are coupled, and a sub tube  52  which projects from a peripheral surface of the main tube  50 . The cooler hose  34  is connected to the sub tube  52  by means of a quick joint  40  (see  FIG. 4 ). 
     Referring to  FIG. 1  again, the connecting pipe  38  is fixed to the engine  10  by way of a clamp  42  and a bracket  44 . In other words, the inlet hose  30  is fixed to the engine  10  at an intermediate position thereof. The inlet hose  30  is fixed at the intermediate position thereof as described above so as to prevent swinging of the inlet hose  30  at the intermediate position. That is, the inlet hose  30  has a long length, and accordingly, when the inlet hose  30  is not fixed at a position separated from fixed ends connected to the engine  10  and the radiator  12  (at the intermediate position), the inlet hose  30  is liable to swing. When the inlet hose  30  swings significantly at the intermediate portion, there may be a case where the inlet hose  30  interferes with other members so that the other members and/or the inlet hose  30  deteriorate or are damaged. In view of the above, the connecting pipe  38  is fixed to the engine  10  so as to suppress significant swinging at the intermediate position. 
     In this embodiment, the bracket  44  is a metal fitting directly or indirectly fixed to the engine  10 , and the bracket  44  is substantially stationary with respect to the engine  10 . The clamp  42  includes an annular body which is mounted on the bracket  44 , and is mounted on an outer periphery of the connecting pipe  38 . As will be described later, the clamp  42  is mounted on the bracket  44  in a substantially stationary manner. On the other hand, the clamp  42  is mounted on the connecting pipe  38  with slight play. The play (gap) is provided between the clamp  42  and the connecting pipe  38  as described above so as to suppress transmission of vibrations of the engine  10  to the connecting pipe  38 . 
     That is, the engine  10  vibrates significantly with the drive of the engine  10  as a matter of course. The bracket  44  fixed to the engine  10  and the clamp  42  also vibrate significantly with the drive of the engine  10 . It is assumed that the connecting pipe  38  is connected to the clamp  42  in a state where the connecting pipe  38  is not movable relative to the clamp  42  at this point of operation. In this case, as described above, the connecting pipe  38  is hard, thus exhibiting poor vibration absorbing characteristics, and hence the connecting pipe  38  also vibrates significantly with the drive of the engine  10 . When the connecting pipe  38  vibrates significantly, there is a possibility that the connection between the connecting pipe  38  and the hoses  34 ,  35 ,  36  will be loosened, and that a stress will act on the connecting pipe  38  thus causing deterioration or damage of the connecting pipe  38 . 
     In view of the above, in the cooling structure disclosed in this specification, slight “play” is provided between the clamp  42  and the connecting pipe  38  as a transmission suppressing portion which suppresses transmission of vibrations. Configurations of the connecting pipe  38  and the clamp  42  are described hereinafter. 
     First, the structure of the connecting pipe  38  is described. As described above and as shown in  FIG. 2  to  FIG. 4 , the connecting pipe  38  is a three-way pipe which includes the main tube  50  having both ends open, and the sub tube  52  standing out from the peripheral surface of the main tube  50 . Both ends of the main tube  50  are inserted into the upstream hose  35  and the downstream hose  36  so that the upstream hose  35  and the downstream hose  36  are fitted on outer peripheries of both ends of the main tube  50 . The upstream hose  35  and the downstream hose  36  which are fitted on both ends of the main tube  50  are firmly fixed on the main tube  50  by means of known hose bands  80 . Further, a pair of protruding portions  54  are formed on the main tube  50  at portions disposed on both sides of the sub tube  52  in the axial direction of the main tube  50 . The protruding portions  54  project outward in the radial direction so as to allow the main tube  50  to locally have a large diameter. The upstream hose  35  and the downstream hose  36  are fitted on the main tube  50  in the vicinity of these protruding portions  54 . 
     The sub tube  52  has a smaller diameter than the main tube  50 , and stands out from the peripheral surface of the main tube  50  at the center in the axial direction of the main tube  50 . An annular rib  56  is formed at an intermediate portion of the sub tube  52 , and the annular rib  56  projects outward so as to allow the sub tube  52  to locally have a large diameter. A portion of the quick joint  40  engages with the annular rib  56 . That is, the upstream hose  35  and the downstream hose  36  are coupled to the main tube  50  using the hose bands  80 . On the other hand, the cooler hose  34  is coupled to the sub tube  52  using the quick joint  40 . The reason for adopting such a configuration is that there is not sufficient space for performing a coupling operation of the cooler hose  34 . 
     That is, in this embodiment, the radiator  12  is installed onto a vehicle and assembled on the engine  10  in a state where the upstream hose  35 , the connecting pipe  38 , and the downstream hose  36  are assembled on the radiator  12 . The connecting pipe  38  and the cooler hose  34  are connected to each other after the radiator  12  and the like are installed onto the vehicle. Accordingly, in performing a connecting operation between the connecting pipe  38  and the cooler hose  34 , it is difficult to ensure sufficient space, and so the connection of the connecting pipe  38  and the cooler hose  34  using a hose band is difficult. In view of the above, in this embodiment, the quick joint  40  is connected to the cooler hose  34  in advance (see  FIG. 4 ), and the quick joint  40  is connected to the sub tube  52  of the connecting pipe  38 . With such a configuration, the sub tube  52  and the cooler hose  34  can be easily connected to each other even with a narrow operation space. The configuration of the quick joint  40  is not particularly limited provided that the quick joint  40  can be connected to the sub tube  52  in one operation in a liquid-tight manner. Accordingly, a known joint configuration can be adopted. 
     A columnar portion  58  is formed at a proximal end of the sub tube  52 . The columnar portion  58  is connected to the peripheral surface of main tube  50  and to a peripheral surface of the sub tube  52 , and the columnar portion  58  has a larger diameter than the sub tube  52 . Several notches are formed in the columnar portion  58  so that the columnar portion  58  is divided into semicircular portions  58   a  and rectangular portions  58   b . The columnar portion  58  is inserted into a center hole  68  of the clamp  42  described later. 
     Next, the configuration of the clamp  42  is described with reference to  FIG. 5  to  FIG. 7 .  FIG. 5  is a view of the clamp  42  in an open state as viewed in the axial direction, and  FIG. 6  is a view of the clamp  42  in a closed state as viewed in the axial direction. Further,  FIG. 7  is a plan view of the clamp  42 . The clamp  42  is roughly divided into a pipe-side connection portion  60  connected to the connecting pipe  38  and an engine-side connection portion  62  connected to the bracket  44 . As shown in  FIG. 5 , the pipe-side connection portion  60  is configured such that first and second clamp pieces  64 ,  66  having a substantially semicircular shape are connected to each other by means of a hinge portion  70  in such a manner as to be openable and closable. The hinge portion  70  is formed at one end of the first clamp piece  64  in the circumferential direction, and an engaging pin  72  which engages with the second clamp piece  66  is formed at the other end of the first clamp piece  64 . An engaging hole  74  which engages with the engaging pin  72  is thinned at one end of the second clamp piece  66 , and the hinge portion  70  is formed at the other end of the second clamp piece  66 . The center hole  68  is formed in the second clamp piece  66 . The center hole  68  is a circular through hole which allows the sub tube  52  and the columnar portion  58  to pass therethrough. 
     In connecting the clamp  42  to the connecting pipe  38 , it is sufficient to perform the following operations. That is, in a state where the sub tube  52  and the columnar portion  58  are made to pass through the center hole  68 , the first clamp piece  64  is rotated to the second clamp piece  66  side so as to cause the engaging pin  72  of the first clamp piece  64  to be engaged with the engaging hole  74  of the second clamp piece  66 . At this point of operation, the pipe-side connection portion  60  formed of the first clamp piece  64  and the second clamp piece  66  forms an annular body which covers an outer periphery of the main tube  50  of the connecting pipe  38 . In this embodiment, an inner diameter Φ 2  of the pipe-side connection portion  60  (see  FIG. 5 ) is slightly larger than an outer diameter Φ 1  of the main tube  50  (see  FIG. 4 ). In other words, the pipe-side connection portion  60  and the main tube  50  have the loose-fitting relationship so that a slight gap is present between an inner surface of the pipe-side connection portion  60  (annular body) and an outer surface of the main tube  50 . The gap functions as a transmission suppressing portion which suppresses transmission of vibrations of the engine  10  to the connecting pipe  38 . A size of the gap (Φ 2 −Φ 1 ) which functions as the transmission suppressing portion may be properly and freely set according to an amount of vibrations of the engine  10 , strength of the connecting pipe  38  or the like. In general, it is sufficient to set the size of the gap to approximately 0.5% to 2% of the outer diameter Φ 1  of the main tube  50 . 
     As described previously, the center hole  68  is formed at the center of the second clamp piece  66 , and the columnar portion  58  of the connecting pipe  38  is made to pass through the center hole  68 . An inner diameter Φ 4  of the center hole  68  (see  FIG. 5 ) is also slightly larger than an outer diameter Φ 3  of the columnar portion  58  (see  FIG. 3 ), and the center hole  68  and the columnar portion  58  have a loose-fitting relationship. A size of the gap (Φ 4 −Φ 3 ) between the center hole  68  and the columnar portion  58  may be set according to an amount of allowable movement of the connecting pipe  38  in the circumferential direction and in the axial direction with respect to the pipe-side connection portion  60 . 
     That is, in this embodiment, the pipe-side connection portion  60  is formed of an annular body which is disposed on the outer periphery of the connecting pipe  38  with a gap, which functions as the transmission suppressing portion, provided therebetween. When such a configuration is adopted, the connecting pipe  38  is movable in the circumferential direction, in the radial direction, and in the axial direction of the connecting pipe  38  with respect to the pipe-side connection portion  60 . As a result, vibrations in various directions resist being transmitted to the connecting pipe  38  so that it is possible to more reliably protect the connecting pipe  38  from the vibrations of the engine  10 . However, when the sub tube  52  or the columnar portion  58  is not provided in such a configuration, the pipe-side connection portion  60  is movable in the circumferential direction and in the axial direction of the pipe-side connection portion  60  without any limitation. On the other hand, as in the case of this embodiment where the center hole  68  is formed in the pipe-side connection portion  60 , and the columnar portion  58  which is made to pass through the center hole  68  is formed on the connecting pipe  38 , due to the contact relationship between the columnar portion  58  and the center hole  68 , an amount of movement of the connecting pipe  38  in the circumferential direction and in the axial direction with respect to the pipe-side connection portion  60  is limited to some extent. As a result, excessive movement of the connecting pipe  38  is restricted. 
     The engine-side connection portion  62  is coupled to an outer peripheral surface of the first clamp piece  64 . A fitting portion  75  which is fitted in a fitting hole  45  of the bracket  44  (see  FIG. 6 ) is formed at an end portion of the engine-side connection portion  62 . The fitting portion  75  is a protrusion having a substantially rectangular shape in cross section. A fitting claw  76  is formed on an outer surface of the fitting portion  75 . The fitting claw  76  has a tapered shape which projects further outward as a distance from a distal end of the fitting portion  75  increases. When the fitting portion  75  is inserted into the fitting hole  45  of the bracket, the fitting claw  76  bites into a peripheral edge of the fitting hole  45  so that the fitting portion  75  is firmly fitted in the fitting hole  45 . When the fitting portion  75  is fitted in the fitting hole  45 , the clamp  42  is firmly connected to the bracket  44  so that the relative movement between the clamp  42  and the bracket  44  is substantially eliminated. Accordingly, when the bracket  44  vibrates, the clamp  42  also vibrates. The bracket  44  is a sheet metal member which is directly or indirectly fastened to the engine  10 . The bracket  44  is fastened to the engine  10  in a substantially stationary state with respect to the engine  10 . Accordingly, when the engine  10  vibrates, the bracket  44  and therefore the clamp  42  also vibrate. 
     To be precise, it is difficult to completely integrally connect the bracket  44  and the clamp  42  to each other, so slight relative movement is also generated between both members  42 ,  44 . Also in such a case, it is sufficient that an allowable displacement amount of the connecting pipe  38  with respect to the engine-side connection portion  62  be larger than an allowable displacement amount of the bracket  44  with respect to the engine-side connection portion  62 . 
     The description is given with respect to advantageous effects obtained by fixing the connecting pipe  38  to the engine  10  by means of the clamp  42  and the bracket  44  having the above-mentioned configuration. In this case, the inlet hose  30  is fixed at an intermediate portion (connecting pipe  38 ) which is separated at a distance from the fixed end and hence, it is possible to prevent the inlet hose  30  from swinging significantly at the intermediate portion. Further, the gap, which functions as the transmission suppressing portion which suppresses transmission of vibrations, is present between the connecting pipe  38  and the clamp  42 . Accordingly, even when the clamp  42  vibrates with the drive of the engine  10 , the vibrations resist being transmitted to the connecting pipe  38 . As a result, it is possible to avoid problems including a problem that the coupling between the connecting pipe  38  and the hoses  35 ,  36 ,  34  is loosened due to vibrations and a problem that the connecting pipe  38  receives stress, thus deteriorating or being damaged. That is, according to the structure disclosed in this specification, it is possible to prevent problems of the connecting pipe  38  caused by vibrations while the intermediate portion of the inlet hose  30  is appropriately fixed. 
     The configuration which has been described heretofore is merely for the sake of example. Other configurations may be changed where appropriate provided that a transmission suppressing portion which suppresses transmission of vibrations is provided between the engine-side connection portion  62  and the connecting pipe  38 . 
     For example, in the description made heretofore, the transmission suppressing portion is formed of a gap between the connecting pipe  38  and the pipe-side connection portion  60 . However, a buffer member which functions as the transmission suppressing portion may be provided between the connecting pipe  38  and the pipe-side connection portion  60  instead of the gap. It is desirable that the buffer member be made of a soft material having low repulsion which allows the displacement of the connecting pipe  38  with respect to the clamp  42  (pipe-side connection portion  60 ). For example, a rubber-based foam material such as EPT-sealer (R) or a rubber-based material such as EPDM may be used. Accordingly, for example, it may be configured such that such buffer members are provided on inner surfaces of the first clamp piece  64  and the second clamp piece  66 , and the buffer members and the connecting pipe  38  come into close contact with each other. In this case, even when the clamp  42  vibrates with vibrations of the engine  10 , the vibrations are absorbed by the buffer members, and the movement of the connecting pipe  38  with respect to the clamp  42  is allowed. As a result, vibrations of the engine  10  resist being transmitted to the connecting pipe  38  so that problems of the connecting pipe  38  caused by vibrations can be prevented. 
     In the description made heretofore, the transmission suppressing portion is provided between the pipe-side connection portion  60  and the connecting pipe  38 . However, the transmission suppressing portion may be disposed at another portion provided that the portion is positioned between the engine-side connection portion  62  and the connecting pipe  38 . For example, when the pipe-side connection portion  60  and the engine-side connection portion  62  are formed of separate components which are connected to each other with the transmission suppressing portion (gap, for example) interposed therebetween, the pipe-side connection portion  60  and the connecting pipe  38  may have a stationary relationship. Even when such a configuration is adopted, vibrations of the engine  10  resist being transmitted to the connecting pipe  38  and hence, problems of the connecting pipe  38  caused by the vibrations can be effectively prevented. 
     Further, in the description made heretofore, the connecting pipe  38  has the three-way configuration. However, the connecting pipe  38  does not necessarily have the three-way configuration provided that the connecting pipe  38  is formed of a pipe which connects two or more hoses (upstream hose  35 , downstream hose  36 ) which form the radiator hose (inlet hose  30 ). Accordingly, the connecting pipe  38  may be formed of a straight pipe having no branch (a pipe having only the main tube  50  without having the sub tube  52 ), or may be formed of a pipe which branches into four or more directions. Further, the connecting pipe  38  (the pipe which is fixed to the engine  10 ) may be provided on an intermediate portion of the outlet hose  32  instead of the intermediate portion of the inlet hose  30 . The connecting pipe  38  which is fixed to the engine  10  may be provided on each of the inlet hose  30  and the outlet hose  32 . 
     REFERENCE SIGNS LIST 
       10  engine,  12  radiator,  14  motor unit,  16  power control unit,  18  radiator core,  20  radiator fan,  22  introduction port,  24  discharge port,  26  inlet pipe,  28  outlet pipe,  30  inlet hose (radiator hose),  32  outlet hose (radiator hose),  34  cooler hose,  35  upstream hose,  36  downstream hose,  38  connecting pipe,  40  quick joint,  42  clamp,  44  bracket,  50  main tube,  52  sub tube,  54  protruding portion,  56  annular rib,  58  columnar portion,  60  pipe-side connection portion,  62  engine-side connection portion,  64  first clamp piece,  66  second clamp piece,  68  center hole,  70  hinge portion,  72  engaging pin,  74  engaging hole,  76  fitting claw,  80  hose band,  100  engine compartment.