Patent Publication Number: US-2011061853-A1

Title: Mounting structure for sensor attached to heat exchanger

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-215176 filed on Sep. 17, 2009, of which the contents are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a mounting structure for a sensor, which is attached, for example, to a heat exchanger that is disposed in a vehicular air conditioning apparatus, and which is provided for the purpose of detecting the temperature of air that has passed through the heat exchanger. 
     2. Description of the Related Art 
     Heretofore, in a vehicular air conditioning apparatus installed in a vehicle such as an automobile or the like, air is drawn into a housing by a fan, and after the air, which has been cooled by an evaporator (heat exchanger) that serves as a cooling means, and air, which as been heated by a heater core that serves as a heating means, are mixed together at a predetermined mixing ratio inside the housing, the air is selectively blown out from blowout ports disposed in the vehicle compartment, whereby the temperature and humidity inside the vehicle compartment can be adjusted. 
     As shown in  FIG. 6 , on an evaporator  1 , which is disclosed in Japanese Laid-Open Patent Publication No. 2006-017406, there is attached a temperature sensor  2  on a side thereof forming a downstream side of air that passes through the evaporator  1 , for detecting the surface temperature of the evaporator  1 . Additionally, based on the temperature that is detected by the temperature sensor  2 , control of air conditioning inside the vehicle compartment of the vehicle is carried out. 
     The temperature sensor  2  is constituted from a housing  4  having a sensor portion  3 , and a cable  5  that is connected to a side surface of the housing  4 . Through insertion of the sensor portion  3  between fins  6  that make up the evaporator  1 , the housing  4  is fixedly attached to a side surface of the evaporator  1 . Further, the cable  5  is connected electrically with respect to a controller or the like installed in the vehicle, and together therewith, the path of the cable  5  is restricted by plural clamp members  7   a ,  7   b , which are attached to the side surface of the evaporator  1 , whereby the cable  5  is guided to a desired location. 
     However, using the above-described conventional technique, when the temperature sensor  2  is mounted, the plural clamp members  7   a ,  7   b  must be installed on the evaporator  1  beforehand in order to arrange the cable  5  thereof along a desired path, which is cumbersome and increases the number of parts, together with increasing the number of assembly steps required to assemble the apparatus. Further, because the clamp members  7   a ,  7   b  are affixed by insertion thereof into the fins  6 , for example, damage to the fins  6  can result, leading to a concern that performance of the heat exchanger will become degraded. 
     SUMMARY OF THE INVENTION 
     A general object of the present invention is to provide a mounting structure for a sensor that is attached to a heat exchanger, which is capable of reducing the number of parts and assembly steps when the sensor is mounted to the air conditioning apparatus. 
     The present invention is characterized by a mounting structure for a sensor attached to a heat exchanger in a vehicular air conditioning apparatus installed in a vehicle, the heat exchanger cooling or heating air supplied to a passage of a casing for blowing the air at a predetermined temperature into a vehicle compartment, and the sensor carrying out temperature detection of the heat exchanger. 
     The sensor comprises a detector attached with respect to the heat exchanger for carrying out detection of temperature of the heat exchanger, and a cable connected to the detector, wherein a guide member is formed in the casing, and the guide member restricts a path of the cable and is capable of retaining the cable. 
     According to the present invention, in the heat exchanger, which is utilized in a vehicular air conditioner installed in the vehicle, a sensor is installed that detects the temperature of the heat exchanger. A cable, which is connected to the detector of the sensor, is restricted to a desired path and is retained by the guide member, which is formed in the casing of the vehicular air conditioner. 
     Accordingly, a cumbersome operation like that of the conventional sensor mounting structure, of attaching each of plural clamp members with respect to the heat exchanger in order to restrict the path of the cable, is no longer necessary. Along therewith, when the sensor is installed, the number of assembly steps can be reduced, together with decreasing the number of parts and associated costs for the mounting structure. 
     The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exterior perspective view showing a vehicular air conditioning apparatus having a heat exchanger, to which a mounting structure for a sensor according to an embodiment of the present invention is applied; 
         FIG. 2  is an enlarged perspective view showing the vicinity of an opening of a first divided casing in the vehicular air conditioning apparatus of  FIG. 1 ; 
         FIG. 3  is an enlarged front view of the vicinity of a cable guide shown in  FIG. 2 ; 
         FIG. 4  is a cross sectional view taken along line IV-IV of  FIG. 2 ; 
         FIG. 5A  is an enlarged plan view showing a condition in which a detection sensor is installed on an evaporator, and  FIG. 5B  is an enlarged side view of  FIG. 5A ; and 
         FIG. 6  is a front view of a heat exchanger on which a sensor is attached according to a conventional technique. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1 , reference numeral  10  indicates a vehicular air conditioning apparatus having a heat exchanger therein on which a sensor according to an embodiment of the present invention is installed. 
     As shown in  FIGS. 1 and 2 , the vehicular air conditioning apparatus  10  includes a casing  12  made up of respective air passages, an evaporator  14  (heat exchanger) for cooling air arranged in the interior of the casing  12 , a heater core (not shown) for heating air, and a duct  18  installed at an opening  16  of the casing  12 , which guides air supplied from a fan into the interior of the casing  12 . Further, in the interior of the casing  12 , there are disposed an air mixing door (not shown) through which heat exchange is performed on the air guided into the casing  12  by means of the evaporator  14  and the heater core, and for creating mixed air by mixing at a predetermined mixing ratio the cool air and the heated air having been adjusted in temperature, and a plurality of blowout port doors for selectively supplying the mixed air into the vehicle compartment from each of the opened blowout ports. 
     The casing  12  is constituted from first and second roughly symmetrical divided casings  20 ,  22 . The duct  18  is installed on the opening  16 , which opens on a side portion of the first divided casing (casing)  20 , and together therewith, the evaporator  14  is accommodated through the opening  16  from the exterior of the casing  12  to the interior thereof. 
     As shown in  FIGS. 2 through 4 , there is disposed in the first divided casing  20  a cable guide (guide member)  24  for guiding a cable  50  of the detection sensor (sensor)  46  referred to below at one side of the opening  16 . The cable guide  24 , for example, is formed from a resin material similar to that of the casing  12  itself, which is disposed on an end surface of the opening  16  on which the duct  18  is installed. Further, the cable guide  24  is formed so as to project in a substantially horizontal direction oriented toward the center of the opening  16 . 
     Further, as shown in  FIGS. 2 through 4 , the cable guide  24  is made up from a planar shaped base portion  26 , which is joined to the end of the opening  16  and projects toward a side of the opening  16 , and a pair of first and second guide walls (wall portions)  28 ,  30 , which project with respect to the base portion  26  toward a direction separating away from the opening  16 . Additionally, the first and second guide walls  28 ,  30  are upstanding perpendicularly with respect to the base portion  26 , and extend in a vertical direction perpendicular to a direction in which the base portion  26  extends. 
     Stated otherwise, the first and second guide walls  28 ,  30  are upstanding toward an exterior side (side of the opening  16 ) of the first divided casing  20 , and the first and second guide walls  28 ,  30  are disposed in parallel while being separated a predetermined distance from each other on the base portion  26 . More specifically, the cable guide  24  is formed to have a U-shape in cross section from the base portion  26  and the pair of first and second guide walls  28 ,  30 . Further, the height of the first and second guide walls  28 ,  30  from the inner wall surface of the base portion  26  is set to be substantially the same or somewhat larger than the diameter of the cable  50 . 
     The first guide wall  28  is disposed more toward the central side of the opening  16  than the second guide wall  30 . A hook member (retainer)  32  capable of retaining the cable  50  of the detection sensor  46 , to be described later, is included on the first guide wall  28 . 
     The hook member  32  is disposed at an end of the first guide wall  28  at a position separated maximally from the base portion  26 . The hook member  32  projects from the end toward the side of the second guide wall  30 , and is formed so as to extend in a longitudinal direction of the first guide wall  28 . Additionally, when the cable  50  is retained by the cable guide  24 , the hook member  32  is held against and holds the outer circumferential surface of the cable  50 , in a state in which the cable  50  abuts against inner wall surfaces of the base portion  26  and the first guide wall  28 . 
     Stated otherwise, the cable  50  is placed in a state such that roughly half of the outer circumferential surface is retained by the base portion  26 , the first guide wall  28  and the hook member  32 . 
     Further, when the cable  50  is retained by the hook member  32 , the cable  50  is retained so as to be displaceable along a longitudinal direction of the cable  50 , but wherein displacement of the cable  50  in a direction to separate away from the cable guide  24 , i.e., displacement in the radial direction of the cable  50 , is restricted. 
     On the other hand, the cable guide  24  has a flexible elasticity about a fulcrum where the cable guide  24  is joined with respect to the casing  12 . More specifically, the cable guide  24  is formed such that the base portion  26  thereof, which is joined to the casing  12 , has a plate thickness (thickness dimension) that enables flexibility, so that the cable guide  24  is tiltable with respect to the casing  12  by a predetermined angle to the horizontal direction. 
     Furthermore, in the first divided casing  20 , a cable hole  34  (see  FIG. 1 ) opens at a position upwardly of the cable guide  24 , and the cable  50  of the later-described detection sensor  46  passes through the cable hole  34  from the interior to the exterior of the first divided casing  20 . 
     As shown in  FIGS. 1 ,  5 A and  5 B, the evaporator  14  comprises a plurality of tubes  36  through which a coolant flows, fins  38  which are bent in a wavelike form in a serpentine pattern between the tubes  36 , and a pair of tanks  40   a ,  40   b  disposed at opposite ends of the tubes and in which the coolant is collected. In addition, on one of the tanks  40   a , the coolant is introduced from the exterior through a supply pipe  42 , and after the coolant has circulated in the interior of the evaporator  14  through the tubes  36  whereupon heat exchange is performed thereby, the coolant is directed out to the exterior from a discharge pipe  44 , which is connected again to the tank  40   a.    
     More specifically, on the evaporator  14 , the plural tubes  36  and fins  38  are separated mutually by equal distances and are arranged in parallel in the widthwise direction, and the tanks  40   a ,  40   b , which are disposed at opposite ends of the tubes  36  and the fins  38  are formed in a boxlike shape, arranged at upper and lower portions of the evaporator  14  (see  FIG. 1 ). 
     Further, the detection sensor  46  is disposed on a side surface of the evaporator  14  in order to detect the surface temperature of the evaporator  14 . The detection sensor  46  includes a main body portion  48  which is mounted on the evaporator  14 , the cable  50  connected to the main body portion  48 , and a connector  52  connected to another end of the cable  50 . The detection sensor  46  is disposed on a side surface of the evaporator  14 , which forms a downstream side thereof when air passes through the evaporator  14  and heat exchange is performed thereon. 
     A detector  56  (see  FIGS. 5A and 5B ) projects on the main body portion  48  from a lower surface thereof. The detector  56  is formed, for example, from a thermistor. Further, the cable  50 , which is connected electrically to the detector  56  in the interior of the main body portion  48 , is connected to a side of the main body portion  48 . 
     In addition, the detector  56  of the detection sensor  46 , which has a projecting columnar shape, is supported on a side surface of the evaporator  14  by insertion thereof between the fins  38  on the evaporator  14 . The main body portion  48  including the detector  56  is affixed with respect to the evaporator  14 . The main body portion  48  of the detection sensor  46  is mounted so as to be roughly parallel to the tanks  40   a ,  40   b  and perpendicular to the direction of extension of the tubes  36 . 
     On the other hand, the cable  50  is formed with a predetermined length, one end thereof being connected to the main body portion  48 , and the connector  52 , which is connected to connection terminals of a non-illustrated controller, being connected to the other end of the cable  50 . In addition, in a condition where the detection sensor  46  is mounted on a side surface of the evaporator  14 , the cable  50  extends in a straight line alongside the evaporator  14 , i.e., in a substantially horizontal direction, and after insertion through the cable guide  24  formed in the first divided casing  20 , the cable  50  is directed upwardly. 
     Further, the cable  50 , after having been guided upward by the cable guide  24 , passes through the cable hole  34  formed in the first divided casing  20  and is inserted therethrough to the outside. At this time, the cable  50  is fixed in place by being sandwiched and gripped between the opening  16  of the first divided casing  20  and the duct  18  that is installed on the opening  16 . 
     The vehicular air conditioning apparatus  10 , having a heat exchanger on which the sensor according to the embodiment of the present invention is mounted, is constructed basically as described above. Next, a method of assembling the detection sensor  46  and the evaporator  14  shall briefly be described. 
     Initially, in a state in which the opening  16  of the first divided casing  20  is opened, when the evaporator  14  is arranged inside the casing  12 , the detection sensor  46  is mounted on a side surface of the evaporator  14  that forms the downstream side thereof. More specifically, the detection sensor  46  is moved to a region on the evaporator  14  where it is desired to detect the surface temperature, and the detector  56  thereof is inserted between the fins  38  of the evaporator  14  and fixed there in place. 
     Next, from the opening  16 , the evaporator  14  together with the detection sensor  46  is inserted into and housed in the interior of the first divided casing  20 , and the cable  50  of the detection sensor  46  is made to extend along one surface side of the evaporator  14  so as to be roughly parallel with the tanks  40   a ,  40   b  of the evaporator  14 . Additionally, the cable  50 , after having been extended to reach the cable guide  24  of the first divided casing  20 , is inserted therethrough to the outer side of the cable guide  24  that faces toward the exterior of the first divided casing  20 . Moreover, the evaporator  14  is fixed at a predetermined position in the interior of the casing  12 , which is made up from the first and second divided casings  20 ,  22 . 
     At this time, the cable  50  is inserted so as to abut against the first guide wall  28  and the base portion  26  that make up the cable guide  24 , and further is inserted between the hook member  32  and the base portion  26  of the cable guide  24 . Consequently, the cable  50  is retained reliably and securely in the cable guide  24  via the base portion  26 , the first guide wall  28 , and the hook member  32 . 
     In addition, after the path of the cable  50  is changed and bent upward at a right angle by the cable guide  24 , the cable  50  extends upwardly and is drawn out to the exterior from the cable hole  34  formed in the first divided casing  20 . 
     Lastly, the duct  18  is installed on the opening  16  of the first divided casing  20 , and by fitting thereof into the opening  16 , a portion of the cable  50  becomes gripped and fixed between the opening  16  and the duct  18 . At this time, while being guided by the cable guide  24 , the cable  50  is pulled out toward the other end side to which the connector  52  is connected. In a tensioned state in which a certain amount of tension is applied to the cable  50 , the cable  50  is fixed in place by the duct  18 . Then, deflection of the cable  50 , etc., does not occur, and thus an appropriate condition is obtained. 
     Then, the connector  52 , which is connected to the cable  50 , for example, is connected to connection terminals of a controller that is installed in the vehicle. Accordingly, the surface temperature of the evaporator  14 , which is detected by the detection sensor  46 , is output to the controller as detection signals via the cable  50  and the connector  52 . 
     In the foregoing manner, with the present embodiment, the detection sensor  46  is mounted with respect to the evaporator  14 , which is used in the vehicular air conditioning apparatus  10 , such that when the surface temperature of the evaporator  14  is detected, the cable guide  24  is formed beforehand in the vicinity of the opening  16  of the first divided casing  20  that makes up the vehicular air conditioning apparatus  10 . Owing thereto, when the detection sensor  46  is installed on the evaporator  14 , the cable  50  is guided suitably by the cable guide  24 , and can be directed to the exterior of the casing  12  along a predetermined path. As a result, there is no need for a plurality of clamp members to restrict the path of the cable  50  of the detection sensor  46 , as was necessary in the assembly structure of the conventional art. Along therewith, the number of assembly steps can be reduced, together with decreasing the number of parts and associated costs for the detection sensor  46 . 
     Further, even in a case where tensile forces are applied to the cable  50  that is retained by the cable guide  24 , for example, by variances in the attachment position of the detection sensor  46  or by pulling of the cable  50  during the assembly operation, because the cable guide  24  is joined in a flexible manner with respect to an end surface of the opening  16  in the first divided casing  20 , such tensile forces can suitably be absorbed, and undesirable movements in the position of the detection sensor  46  can be avoided. Further, faulty operation of the detector  56  or the like, which is a concern in the case that tension is applied to the detector  56  via the cable  50 , can be avoided. 
     Furthermore, the cable guide  24  includes the pair of first and second guide walls  28 ,  30 , and since the cable  50  is retained between the first and second guide walls  28 ,  30 , the cable  50  is suitably held by the pair of first and second guide walls  28 ,  30  and separation of the cable  50  from the cable guide  24  can be prevented. 
     Still further, on the aforementioned first guide wall  28 , since a hook member  32  is provided, which is cable of retaining the cable  50  under a condition in which the cable  50  abuts against inner wall surfaces of the base portion  26  and the first guide wall  28 , the cable  50  can reliably be retained by the cable guide  24  including the first guide wall  28 . Moreover, because the hook member  32  retains the cable  50  so as to be displaceable in the longitudinal direction, even in the case that the cable  50  is displaced along the longitudinal direction by variances in the installation position of the detection sensor  46  or the like, the cable  50  can appropriately be displaced freely under a condition in which the cable  50  is retained by the hook member  32 . 
     More specifically, the hook member  32 , which is provided on the first guide wall  28 , allows displacement of the cable  50  along the longitudinal direction, while conversely, the hook member  32  restricts displacement of the cable  50  in a direction whereby the cable  50  would separate away from the cable guide  24 , i.e., in the radial direction of the cable  50 . 
     Still further, since it is not necessary to install a plurality of clamp members, as used in the sensor mounting structure of the conventional art, with respect to the fins  38  of the evaporator  14 , damage to the fins  38 , which is a problem when such clamp members are installed, can be avoided. 
     Further, because the cable  50  of the detection sensor  46  is firmly retained by the cable guide  24 , the cable  50  is not subjected to bending in the vicinity of the side surface of the evaporator  14 , and thus the cable  50  coming into contact with the air mixing door (not shown), which would be of concern if the cable  50  were to become bent, can be avoided. 
     The mounting structure for a sensor, which is attached to a heat exchanger according to the present invention, is not limited to the aforementioned embodiment. It is a matter of course that various changes and modifications may be adopted without departing from the scope and essence of the invention as set forth in the appended claims.