Patent Publication Number: US-2006014404-A1

Title: Sensor and method of manufacturing the same

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application is based on Japanese Patent Application No. 2004-208984 filed on Jul. 15, 2004, the disclosure of which is incorporated herein by reference.  
     FIELD OF THE INVENTION  
      The present invention relates to a sensor and a method of manufacturing the sensor.  
     BACKGROUND OF THE INVENTION  
      Generally, as shown in  FIG. 11 , a sensor is provided with a sensing unit (not shown) for generating electrical signals responding to a physical quantity, terminals  50  for electrically connecting with the external, a connector housing  40  and the like, for example, referring to JP-2003-302292A. The terminals  50  are accommodated in the connector housing  40 , which is inserted into a housing  10 . The sensing unit is arranged in a protection tube  30 .  
      In this case, the connector housing  40  is insert-molded, while the components of the sensor other than the connector housing  40  are beforehand assembled. In order to properly set the position relation between the connector housing  40  and the terminals  50 , the terminals  50  are fixed in a die of the connector housing  40 . Then, a resin is injected into the die to form the connector housing  40 .  
      However, it is difficult to insert the terminals  50  in the die for forming the connector housing  40 . Therefore, the manufacture performance of the sensor is impaired.  
     SUMMARY OF THE INVENTION  
      In view of the above-described disadvantages, it is an object of the present invention to provide a sensor and a method of manufacturing the sensor to improve a manufacture performance of the sensor.  
      According to an aspect of the present invention, a sensor includes a sensing unit for generating electrical signals responding to a physical quantity, a plurality of terminals for an electrical connection with an external, a plurality of signal wires for transmitting the electrical signals to the terminals, a connector housing in which the terminals are accommodated, and an electrically isolating case, to which the terminals are fixed. The terminals and the electrically isolating case are inserted in the connecter housing.  
      Because the multiple terminals are fixedly connected to the single electrically isolating case, the terminals can be readily inserted into the connector housing. Moreover, because the terminals and the electrically isolating case are to be inserted in the connector housing, the connector housing can be singly formed without being insert-molded. That is, it is unnecessary to insert the terminals in a die when the connector housing is formed. Accordingly, the manufacture performance of the sensor can be improved.  
      According to another aspect of the present invention, a sensor includes a sensing unit for generating electrical signals responding to a physical quantity, a plurality of terminals for an electrical connection with an external, a plurality of signal wires for transmitting the electrical signals to the terminals, a connector housing in which the terminals are accommodated, a plurality of junction portions made of a metal, and an electrically isolating case, to which the junction portions are fixed. The terminals and the signal wires are joined to the junction portions. The terminals and the electrically isolating case are inserted in the connecter housing.  
      Because the multiple terminals are fixedly connected to the single isolating case through the junction portions, the terminals can be readily inserted into the connector housing. Moreover, because the terminals and the isolating case are to be inserted in the connector housing, the connector housing can be singly formed without being insert-molded. It is unnecessary to insert the terminals in the die when the connector housing is formed. Accordingly, the manufacture performance of the sensor can be improved.  
      Moreover, in this case, the heat capacity of the junction portion can be set as an intermediate valve between the heat capacity of the terminal and that of the signal wire. Therefore, the junction portion can be joined to both the signal wire and the terminal. Accordingly, the terminals and the signal wires can be electrically connected with each other through the junction portions, even if the heat-capacity difference between the terminals and the signal wires is large.  
      According to more another aspect of the present invention, a manufacturing method is provided for a sensor which includes a sensing unit for generating electrical signals responding to a physical quantity, a plurality of terminals for an electrical connection with an external, a plurality of signal wires for electrically connecting the sensing unit to the terminals, a connector housing, a plurality of junction portions made of a metal, and an electrically isolating case. The method includes forming the connector housing, insert-molding the electrical isolating case by a die, in which the junction portions are beforehand arranged, joining the terminals and the signal wires to the junction portions after the step of insert-forming, and inserting the terminals and the electrically isolating case in the connector housing after the step of joining.  
      Thus, the sensor can be suitably manufactured.  
      Preferably, the method of manufacturing the sensor includes preparing a terminal member which is constructed of a connection portion and the terminals before the step of joining. The terminals are arranged with a predetermined position relation and connected with each other through the connection portion. The connection portion is to be separated from the terminals after the terminals are joined to the junction portions at the step of joining.  
      Because the connection portion is separated from the terminals after the terminals are joined to the junction portions, the predetermined position relation among the multiple terminals can be properly maintained, as compared with the case where the multiple terminals are singly joined to the junction portions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which:  
       FIG. 1  is a partially cross-sectional view showing a whole construction of a temperature sensor according to a first embodiment of the present invention;  
       FIG. 2  is a plan view showing a case forming process of the temperature sensor according to the first embodiment;  
       FIG. 3A  is a plan view showing a junction member  60 A, and  FIG. 3B  is a cross-sectional view taken along a line IIIB-IIIB in  FIG. 3A ;  
       FIG. 4  is a partially cross-sectional view showing a first joining process of the temperature sensor according to the first embodiment;  
       FIG. 5A  is a plan view showing a second joining process of the temperature sensor according to the first embodiment, and  FIG. 5B  is a cross-sectional view taken along a line VB-VB in  FIG. 5A ;  
       FIG. 6  is a plan view showing a terminal member  50 A according to the first embodiment;  
       FIG. 7A  is a partially cross-sectional view showing an inserting process of the temperature sensor according to the first embodiment, and  FIG. 7B  is a partially cross-sectional view taken along a line VIIB-VIIB in  FIG. 7A ;  
       FIG. 8  is a cross-sectional view showing a connector housing  40  according to the first embodiment;  
       FIG. 9  is a plan view showing a case forming process of a temperature sensor according to a second embodiment of the present invention;  
       FIG. 10  is a partially cross-sectional view showing a joining process of the temperature sensor according to the second embodiment; and  
       FIG. 11  is a partially cross-sectional view showing a whole construction of a temperature sensor according to a related art. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      (First Embodiment)  
      A first embodiment of the present invention will be described with reference to  FIGS. 1-8 . As shown in  FIG. 1 , a sensor is provided with a sensing unit  20  for generating electrical signals responding to a physical quantity (e.g., temperature), multiple terminals  50  for an electrically connection with the external, multiple signal wires  21  for electrically connecting the sensing unit  20  to the multiple terminals  50 , a housing  10 , a connector housing  40 , an electrically isolating case  70  and the like.  
      The sensing unit  20  (e.g., thermistor element) is made of, for example, a ceramic, a silicon semiconductor or the like, so that the resistance thereof is variable responding to a temperature and the sensor is suitably used for a temperature sensor.  
      The housing  10  having a stepped cylinder shape is made of a metal (e.g., stainless steel). The sensing unit  20 , being disposed at the side of one end of the housing  10 , is accommodated in a tubular protection unit  30  which is made of a metal, for example. The protection unit  30  has a bottomed cylindrical shape with one end opened and other end closed. The protection unit  30  is inserted through a cylinder-tubular support unit  31 , which is made of a metal. The protection unit  30  and the support unit  31  are integrated by brazing or the like, and inserted into a welding cylinder portion  101 , which is located at the one end of the housing  10 . The support unit  31  is joined to the welding cylinder portion  101  by, for example, laser welding.  
      The cylindrical connector housing  40  is made of, for example, a resin. One end (insertion end) of the cylindrical connector housing  40  is inserted into (engaged with) other end of the housing  10 . The housing  10  is swaged (crimped) toward the diametrically inner side thereof to construct a swaged portion  102 , which is located at the other end of the housing  10  and at the axially outer side of the insertion end of the cylindrical connector housing  40 . Thus, the connector housing  40  is fixedly connected with the housing  10 .  
      An O-ring  11 , being arranged around the insertion end of the connector housing  40 , is engaged with both the inner surface of the housing  10  and the outer surface of the insertion end of the connector hosing  40  to seal therebetween.  
      The sensing unit  20  is electrically connected with the signal wires  21  (e.g., two signal wires  21 ). The signal wire  21 , being covered with a sheathing tube (not shown), is electrically connected to the terminal  50  through a junction portion  60 . The multiple terminals  50  (e.g., two terminals  50 ) and the multiple junction portions  60  (e.g., two junction portions  60 ) are made of metals. Thus, the electrical signals generated by the sensing unit  20  can be transmitted to the terminals  50  through the signal wires  21  and the junction portions  60 .  
      The junction portions  60  and the terminals  50  are fixed to the electrically isolating case  70 . The terminals  50  and the electrically isolating case  70  (isolating case  70 ) are inserted in the connector housing  40 .  
      Next, the method of manufacturing the temperature sensor with the above-described construction will be described.  
      At first, referring to  FIG. 2 , the isolating case  70  will be formed in a case forming process. Before the case forming process, a junction member  60 A made of a metal (e.g., stainless steel) is prepared as shown in  FIG. 3A . The junction member  60 A includes a connection portion  61  and the two junction portions  60  with a plate shape, for example. The junction portions  60 , extending parallel to each other, are connected with each other through the connection portion  61 . Referring to  FIG. 3B , each of the junction portions  60  is provided with a notch  601 , which is positioned near the connection portion  61 . Thus, the connection portion  61  can be readily separated from the junction portions  60  at the later-described process.  
      Then, at the case forming process, the junction member  60 A is arranged in a die (not shown) of the isolating case  70 . Thereafter, an electrically isolating resin such as a polyphenylene sulfide (PPS) is injected into the die, so that the isolating case  70  is insert molded. In this case, parts of the junction portions  60  are embedded in the isolating case  70 .  
      After the isolating case  70  is formed, the connection portion  61  is bent at the notch  601 , to be separated from the junction portions  61 . Therefore, the two junction portions  60  are electrically separated from each other.  
      The isolating case  70  is provided with a tube insertion groove  701  in which the protection unit  30  is to be inserted, and a pair of wire insertion grooves  702  in which the signal wires  21  are respectively to be inserted. The junction portions  60  are partly exposed in the wire insertion groove  702 .  
      Referring to  FIG. 4 , after the isolating case  70  is insert-molded at the case forming process, the signal wires  21  and the terminals  50  will be joined to the junction portions  60  respectively at a first joining process and a second joining process.  
      Specifically, at the first joining process, the protection unit  30  where the sensing unit  20  is accommodated is inserted in the tube insertion groove  701  of the insulating case  70 . The signal wires  21  are respectively inserted in the wire insertion grooves  702  of the isolating case  70 . In the wire insertion groove  702 , the signal wires  21  are respectively joined to the junction portions  60  by a spot welding or the like.  
      Then, after the first joining process, the terminals  50  will be respectively connected to the junction portions  60  at the second joining process, referring to  FIGS. 5A and 5B . Before the second joining process, a terminal member  50 A is prepared as shown in  FIG. 6 . The terminal member  50 A includes the two terminals  50  which are arranged with a predetermined position relation, and a connection portion  51  connecting the terminals  50  to each other. Preparing the terminal member  50 A can be also performed at any time (e.g., before first joining process) before the second joining process.  
      Thus, at the second joining process, the terminals  50  of the terminal member  50 A are respectively joined to the junction portions  60  by a spot welding or the like. Thereafter, the connection portion  51  is separated from the terminals  50 , so that the terminals  50  are divided from each other. Then, the tube insertion groove  701  and the wire insertion grooves  702  of the isolating case  70  are filled with an epoxy resin or the like. Thus, a resin layer  80  is formed at the isolating case  70 , to fix the junction portions  60  and the terminals  50  to the isolating case  70 .  
      After the second joining process, the terminals  50  and the isolating case  70  will be inserted into the connector housing  40  at an inserting process with reference to  FIGS. 7A and 7B .  
      Before the inserting process, the cylindrical connector housing  40  is prepared (formed) at a connector housing forming process. Referring to  8 , the connector housing  40 , being made of an electively isolating resin such as a polyphenylene sulfide (PPS), is formed to include a connector engagement cylinder portion  401  and a case engagement cylinder portion  403 . The connector engagement cylinder portion  401  and the case engagement cylinder portion  403  are sequentially arranged in an axial direction of the connector housing  40 , and communicated with each other by two penetration holes  402 . The penetration holes  402 , extending in the axial direction of the connector housing  40 , penetrate the partition wall between the connector engagement cylinder portion  401  and the case engagement cylinder portion  403 .  
      The connector housing forming process can be also performed at any time (e.g., before case forming process) before the inserting process, to prepare the connector housing  40 .  
      Then, at the inserting process, while the tips of the two terminals  50  are respectively positioned to correspond to the penetration holes  402 , the terminals  50  and the isolating case  70  are press-inserted into the connector housing  40 . Thus, the terminals  50  are inserted through the penetration holes  402 , so that ends of the terminals  50  protrude into the connector engagement cylinder portion  401 . The isolating case  70  is engaged with the case engagement portion  403 . The connector engagement cylinder portion  401  of the connector housing  40  is to be engaged with a housing (not shown) of other connector.  
      Thereafter, an epoxy resin or the like is supplied to the case engagement cylinder portion  403 , to form a resin layer  90  which seals the overlapping part between the isolating case  70  and the case engagement cylinder portion  403 . Thus, the isolating case  70  is fixed to the connector housing  40  through the resin layer  90 .  
      Thus, the assembly having the above-described construction is inserted into the housing  10 . In this case, the protection unit  30  and the support unit  31  are inserted through the welding cylinder portion  101  of the housing  10  to protrude from the housing  10 . Thereafter, the housing  10  is swaged at the swaged portion  102  toward the diametrically inner side of the housing  10 . The welding cylinder portion  101  is joined to the support unit  31 . Thus, the temperature sensor shown in  FIG. 1  is manufactured.  
      According to this embodiment, because the two terminals  50  are fixedly connected to the single isolating case  70  through the junction portions  60 , the two terminals  50  can be readily inserted into the connector housing  40 . Moreover, because the terminals  50  and the isolating case  70  are to be inserted in the connector housing  40  after it is manufactured, the connector housing  40  can be singly formed without being insert-molded. That is, it is unnecessary to insert the terminals  50  in the die when the connector housing  40  is formed. Accordingly, the manufacture performance of the sensor can be improved.  
      In the case where the heat-capacity difference between the terminal  50  and the signal wire  21  is large, it may be unfeasible to join the signal wire  21  to the terminal  50  by soldering, welding or the like. According to this embodiment, the heat capacity of the junction portion  60  is set as an intermediate valve between the heat capacity of the terminal  50  and that of the signal wire  21 . Therefore, the junction portion  60  can be joined to both the signal wire  21  and the terminal  50 . Accordingly, the terminals  50  and the signal wires  21  can be electrically connected with each other through the junction portions  60 .  
      Furthermore, according to this embodiment, the terminal member  50 A including the two terminals  50  and the connection portion  51  is prepared. The terminals  50  are arranged with the predetermined position relation and connected with each other through the connection portion  51 , which is to be separated from the terminals  50  after the terminals  50  are joined to the junction portions  60 . Therefore, the predetermined position relation between the two terminals  50  can be maintained even after the connection portion  51  is separated. Accordingly, the joining process of the terminal  50  is simplified.  
      (Second Embodiment)  
      A second embodiment of the present invention will be described referring to  FIGS. 9 and 10 .  
      In the above-described first embodiment, the junction portions  60  are fixed to the isolating case  70 . The terminals  50  and the signal wires  21  are joined to the junction portions  60 . According to the second embodiment, the terminals  50  are fixed to the single isolating case  70 , and the signal wires  21  are respectively joined to the terminals  50 .  
      Specifically, as shown in  FIG. 9 , at the case forming process, the terminal member  50 A is arranged in the die (not shown) of the isolating case  70 . Then, the electrically isolating resin is injected into the die, and the isolating case  70  is insert-molded. In this case, the terminal member  50 A (terminals  50 ) is partly embedded in the isolating case  70 , and partly exposed at the wire insertion groove  702 . Thereafter, the connection portion  51  is separated from the terminals  50 , so that the two terminals  50  are separated from each other.  
      Then, as shown in  FIG. 10 , at the joining process, the signal wires  21  are respectively joined to the terminals  50  which are partly exposed at the wire insertion groove  702 . Thereafter, the epoxy resin is supplied to the tube insertion groove  701  and the wire insertion grooves  702  of the isolating case  70 .  
      Next, similarly to the first embodiment, the terminals  50  and the isolating case  70  are inserted into the connector housing  40 , and the connector housing  40  is fixed to the housing  10 .  
      According to this embodiment, the two terminals  50  are fixedly connected to the single isolating case  70 , so that the terminals  50  can be readily inserted in the connector housing  40 . Moreover, because the terminals  50  and the isolating case  70  are to be inserted into the connector housing  40  after it is manufactured, the connector housing  40  can be singly formed without being insert-molded. Accordingly, it is unnecessary to insert the terminals  50  in the die of the connector housing  40  when the connector housing  40  is formed. Therefore, the manufacture performance of the sensor can be improved.  
      Moreover, according to this embodiment, the terminal member  50 A including the two terminals  50  and the connection portion  51  is prepared. The terminals  50  are arranged with the predetermined position relation, and connected with each other through the connection portion  51 , which will be separated from the terminals  50  after the terminals  50  are joined to the isolating case  70 . Therefore, the predetermined position relation between the two terminals  50  can be maintained even after the connection portion  51  is separated. Thus, the joining process of the terminals  50  is simplified.  
      The construction of the sensor and the method of manufacturing the sensor, which have not been described in the second embodiment, are the same with those in the first embodiment.  
      (Other Embodiment)  
      Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art.  
      In the above-described embodiments, the sensor and the manufacturing method thereof are suitably used for the temperature sensor. However, the sensor and the manufacturing method thereof according to the present invention can be also used for other sensors.  
      Such changes and modifications are to be understood as being in the scope of the present invention as defined by the appended claims.