Patent Publication Number: US-2022221361-A1

Title: Physical quantity sensor-fixing structure

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present patent application claims the priority of Japanese patent application No. 2021-002799 filed on Jan. 12, 2021, and the entire contents of Japanese patent application No. 2021-002799 are hereby incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to a physical quantity sensor-fixing structure. 
     BACKGROUND ART 
     Conventionally, vehicles are equipped with physical quantity sensors that detect various physical quantities. For example, Patent Literature 1 discloses an integrated temperature and pressure sensor device to detect temperature and pressure in an intake manifold of an internal combustion engine. 
     This integrated temperature and pressure sensor device includes a pressure sensor cell, a temperature sensor, pressure sensor terminals, temperature sensor terminals, and a resin case housing these components. The case is made of an overmold resin member and a premold resin member. The temperature sensor has a temperature sensing element and a lead wire electrically connected to the temperature sensor terminal, and is configured in such a manner that the lead wire is connected to the temperature sensor terminal inside the premold. The temperature sensing element is arranged on the inner side of a guard provided to prevent collision with foreign matter flowing into the intake manifold, and the lead wire is led out of the premold on the inner side of the guard. The temperature sensing element is supported by the lead wire being led out of the premold without being in contact (in a contactless manner) with the guard. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: JP 2020-180944A 
       
    
     SUMMARY OF THE INVENTION 
     In the integrated temperature and pressure sensor device described in Patent Literature 1, since the temperature sensing element of the temperature sensor is supported by the lead wire, the temperature sensing element is likely to be shaken by, e.g., vibration of the internal combustion engine, which may raise concerns about durability depending on the mounting position of the sensor device. In addition, when the temperature sensor is used to detect, e.g., temperature of a heat-generating portion such as electric motor or electric wire, temperature detection accuracy may decrease due to changes in a distance between the temperature sensing element and the heat-generating portion caused by vibration. 
     Therefore, it is an object of the invention to provide a physical quantity sensor-fixing structure, in which a physical quantity sensor having a detection unit to detect a physical quantity and lead wires can be supported, with increased support rigidity, on conductive support members connected to the lead wires. 
     So as to achieve the above object, one aspect of the invention provides a physical quantity sensor-fixing structure, comprising:
         a holder holding a physical quantity sensor comprising a detection unit to detect a physical quantity and a plurality of lead wires connected to the detection unit, the holder fixing the physical quantity sensor to a plurality of conductive support members to be respectively connected to the plurality of lead wires,   wherein the holder comprises a main body member comprising a housing portion to house at least a portion of the physical quantity sensor, and a lid member covering at least a portion of the housing portion.       

     Effect of the Invention 
     According to the present invention, it is possible to provide a physical quantity sensor-fixing structure, in which a physical quantity sensor having a detection unit to detect a physical quantity and lead wires can be supported, with increased support rigidity, on conductive support members connected to the lead wires. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing a holder integrated-type physical quantity detection device to which a physical quantity sensor-fixing structure in an embodiment of the present invention is applied. 
         FIG. 2  is a cross-sectional view taken along line A-A in  FIG. 1 . 
         FIGS. 3A and 3B  are perspective views showing an assembly process. 
         FIGS. 4A and 4B  are a front view and a side view showing a main body member of a holder configured to hold the physical quantity sensor. 
         FIG. 5A  is a cross-sectional view taken along line B-B in  FIG. 4A . 
         FIG. 5B  is a cross-sectional view taken along line C-C in  FIG. 4A . 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Embodiment 
       FIG. 1  is a perspective view showing a holder integrated-type physical quantity detection device to which a physical quantity sensor-fixing structure in an embodiment of the invention is applied.  FIG. 2  is a cross-sectional view taken along line A-A in  FIG. 1 .  FIGS. 3A and 3B  are perspective views showing an assembly process.  FIGS. 4A and 4B  are a front view and a side view showing a main body member of a holder configured to hold the physical quantity sensor.  FIG. 5A  is a cross-sectional view taken along line B-B in  FIG. 4A  and  FIG. 5B  is a cross-sectional view taken along line C-C in  FIG. 4A . 
     A physical quantity sensor-fixing structure in the present embodiment is configured to fix a physical quantity sensor to plural conductive support members by a holder. Although the case where the physical quantity sensor is a thermistor  1  to detect temperature will be described as an example in the present embodiment, the physical quantity sensor may be, e.g., a thermocouple. In addition, the physical quantity sensor is not limited to a sensor to detect temperature as a physical quantity, and may be, e.g., a magnetic sensor to detect magnetic field intensity. 
     The thermistor  1  has a detection unit  10  to detect temperature and plural lead wires  11 ,  12  connected to the detection unit  10 . As shown in  FIG. 2 , the detection unit  10  is composed of a flat plate-shaped sintered metal oxide  100 , a pair of electrode plates  101 ,  102  sandwiching the sintered metal oxide  100 , and a sealing body  103  sealing the sintered metal oxide  100  and the pair of electrode plates  101 ,  102 . The sealing body  103  is made of, e.g., a glass sealing material and is formed in an elliptical sphere shape. However, the material or shape of the sealing body  103  is not limited thereto, and an appropriate material or shape can be used. 
     The lead wires  11 ,  12  of the thermistor  1  are made of, e.g., a highly-electrical conductive metal in wire shape such as tin-plated copper wire and are arranged in such a manner that respective end portions are connected to the pair of electrode plates  101 ,  102  of the detection unit  10 . The lead wires  11 ,  12  are bent at four locations, respectively at bent portions  111 - 114  and bent portions  121 - 124 , as shown in  FIG. 3A . 
     The thermistor  1  is held by a holder  2  composed of a resin. The holder  2  has a main body member  3  having a housing portion  30  to house at least a portion of the thermistor  1  and a lid member  4  covering a portion of the housing portion  30 , and is formed in a rectangular parallelepiped shape as a whole. Each of the main body member  3  and the lid member  4  is an injection-molded article made of a resin. As the resin member of the main body member  3 , it is preferable to use a material having a thermal conductivity of not less than 1 W/m·K and it is more preferable to use a material having a thermal conductivity of not less than 3 W/m·K. 
     The holder  2  fixes the thermistor  1  to plural conductive support members  51 ,  52 . The plural conductive support members  51 ,  52  are, e.g., terminals of a connector, but are not limited thereto and may be, e.g., wires partially protruding outside from a case of an electronic device such as control device. The conductive support members  51 ,  52  are made of rod-shaped metal conductors having a larger cross-sectional area than the lead wires  11 ,  12  of the thermistor  1 , have higher rigidity than the lead wires  11 ,  12 , and extend parallel to each other. 
     Other end portions of the lead wires  11 ,  12  of the thermistor  1  on the opposite side to the end portions connected to the detection unit  10  are respectively connected to the conductive support members  51 ,  52 . The lead wires  11 ,  12  are connected to the conductive support members  51 ,  52  by, e.g., welding. However, the lead wires  11 ,  12  may be connected to the conductive support members  51 ,  52  by soldering or crimping. 
     Hereinafter, the lead wire  11 , one of the lead wires  11 ,  12 , is referred to as the first lead wire  11  and the other lead wire  12  is referred to as the second lead wire  12 . In addition, of the conductive support members  51 ,  52 , the conductive support member  51  connected to the first lead wire  11  is referred to as a first conductive support member  51 , and the conductive support member  52  connected to the second lead wire  12  is referred to as a second conductive support member  52 . 
     As shown in  FIG. 4 , a recess  300  to house the detection unit  10 , a first recessed groove  301  to house at least a portion of the first lead wire  11 , a second recessed groove  302  to house at least a portion of the second lead wire  12 , and a connection groove  31  connecting the first recessed groove  301  to the second recessed groove  302  are formed on the main body member  3 . Of those, the recess  300  and the first and second recessed grooves  301 ,  302  are in communication with each other and form the housing portion  30 . In this regard, the connection groove  31  may not be formed on the main body member  3 . 
     As shown in  FIGS. 2 and 3A , the recess  300  is composed of a hemispherical bottom-side portion  300   a  curved along the outline of the sealing body  103  of the detection unit  10  and an opening-side portion  300   b  located on the opening side relative to the bottom-side portion  300   a , and the opening-side portion  300   b  opens on a flat upper surface  3   a  of the main body member  3 . A step surface  300   c  is formed at a boundary between the bottom-side portion  300   a  and the opening-side portion  300   b , and the recess  300  is formed in such a manner that an inner diameter of the opening-side portion  300   b  is larger than an inner diameter of the step surface  300   c  (the largest inner diameter of the bottom-side portion  300   a ). 
     In the present embodiment, the first and second recessed grooves  301 ,  302  respectively house portions of the first and second lead wires  11 ,  12 , and connections between the first lead wire  11  and the first conductive support member  51  and between the second lead wire  12  and the second conductive support member  52  are made outside the holder  2 . 
     As shown in  FIG. 3A , a first fitting hole  321  to house an end portion of the first conductive support member  51  and a second fitting hole  322  to house an end portion of the second conductive support member  52  are formed on the main body member  3 . The main body member  3  is fixed to the first and second conductive support members  51 ,  52  by fitting the first and second conductive support members  51 ,  52  into the first and second fitting holes  321 ,  322 . The first conductive support member  51  is provided with protrusions  511 ,  512  to prevent it from slipping out of the first fitting hole  321 . Likewise, the second conductive support member  52  is provided with protrusions  521 ,  522  to prevent it from slipping out of the second fitting hole  322 . 
     The first and second fitting holes  321 ,  322  are open on a side surface  3   b  of the main body member  3  that is perpendicular to a longitudinal direction of the first and second conductive support members  51 ,  52 , and the first and second recessed grooves  301 ,  302  are also open on the side surface  3   b . The first and second lead wires  11 ,  12  are arranged in such a manner that tip portions to be connected to the first and second conductive support members  51 ,  52  are led out of the holder  2  from ends of the first and second recessed grooves  301 ,  302  on the side surface  3   b  side. Portions of the main body member  3  between the first conductive support member  51  and the first recessed groove  301  and between the second conductive support member  52  and the second recessed groove  302  serve as partition wall portions  331 ,  332  that separate the first and second conductive support members  51 ,  52  from the first and second recessed grooves  301 ,  302 . 
     The housing portion  30  (the recess  300  and the first and second recessed grooves  301 ,  302 ) is open toward a predetermined direction perpendicular to an alignment direction and a longitudinal direction of the first and second conductive support members  51 ,  52  in the vicinity of the holder  2  (a direction perpendicular to the paper surface of  FIG. 4A  and toward the near side of the paper). The first and second lead wires  11 ,  12  of the thermistor  1  housed in the housing portion  30  are prevented from slipping out of the first and second recessed grooves  301 ,  302  by the lid member  4 . 
     The lid member  4  has a flat plate portion  40 , and a pair of arm portions  41 ,  42  extending from both longitudinal ends of the plate portion  40  in a direction perpendicular to a longitudinal direction of the plate portion  40  (the alignment direction of the first and second conductive support members  51 ,  52 ). The plate portion  40  covers the first and second recessed grooves  301 ,  302 . Locking protrusions  411 ,  412  engaging with the main body member  3  are respectively provided on the arm portions  41 ,  42 . 
     A lid member-housing portion  34  to house the lid member  4  is formed on the main body member  3 . As shown in  FIG. 5B , the lid member-housing portion  34  is composed of a recessed portion  340  to house the plate portion  40  of the lid member  4 , and groove portions  341 ,  342  to respectively house the arm portions  41 ,  42 . The groove portions  341 ,  342  respectively have locking surfaces  341   a ,  342   a  that engage with the locking protrusions  411 ,  412 . The first and second recessed grooves  301 ,  302  are formed so as to be recessed from a bottom surface  340   a  of the recessed portion  340 . Depths of the first and second recessed grooves  301 ,  302  from the bottom surface  340   a  are greater than thicknesses of the first and second lead wires  11 ,  12 . The first and second lead wires  11 ,  12  housed in the first and second recessed grooves  301 ,  302  may or may not be in contact with the plate portion  40  of the lid member  4 . 
     The detection unit  10  of the thermistor  1  is fixed to the main body member  3  inside the recess  300  by a curable resin  20 . An epoxy resin can be suitably used as the curable resin  20 , and it is more preferable to use an epoxy resin particularly having a thermal conductivity of not less than 1 W/m·K. A portion of the curable resin  20  may enter the first and second recessed grooves  301 ,  302 , and may enter between the bottom surface  340   a  of the recessed portion  340  and the plate portion  40  of the lid member  4 . 
     Next, a procedure for assembling the holder  2  and surrounding parts will be described. This assembly procedure includes a first housing step of placing the thermistor  1  so as to be housed in the housing portion  30  of the main body member  3 , a second housing step of placing the lid member  4  so as to be housed in the lid member-housing portion  34  of the main body member  3 , an injection step of injecting the curable resin  20  in liquid form before curing into the recess  300  housing the detection unit  10  of the thermistor  1 , a fitting step of fitting the first and second conductive support members  51 ,  52  into the first and second fitting holes  321 ,  322  of the main body member  3 , and a connection step of connecting the first and second lead wires  11 ,  12  to the first and second conductive support members  51 ,  52 . The order of these steps is not specifically limited, except that the first housing step is performed before the second housing step and the injection step. 
     A holder integrated-type physical quantity detection device  6 , which includes the thermistor  1  and the holder  2  and in which the thermistor  1  is fixed to the first and second conductive support members  51 ,  52  by the holder  2 , is obtained by this assembly procedure. 
     Effects of the Embodiment 
     According to the embodiment of the invention described above, the following effects are obtained. 
     (1) Since the thermistor  1  is housed in the housing portion  30  of the main body member  3  and at least a portion of the housing portion  30  is covered with the lid member  4 , the thermistor  1  is prevented from slipping out of the housing portion  30  and is held by the holder  2 . This makes it possible to increase support rigidity as compared to when the detection unit  10  of the thermistor  1  is supported by only the first and second lead wires  11 ,  12 . 
     (2) Since the housing portion  30  has the recess  300  to house the detection unit  10  of the thermistor  1  and the first and second recessed grooves  301 ,  302  to house the first and second lead wires  11 ,  12 , it is possible to reliably hold the thermistor  1 . 
     (3) The recess  300  and the first and second recessed grooves  301 ,  302  are open toward a predetermined direction perpendicular to the alignment direction of the first and second conductive support members  51 ,  52 . Therefore, in the first housing step, the thermistor  1  can be easily placed so as to be housed in the housing portion  30  of the main body member  3  and also the first and second lead wires  11 ,  12  can be arranged respectively along the first and second conductive support members  51 ,  52  and it is easy to connect therebetween. 
     (4) Since the first and second lead wires  11 ,  12  are arranged in such a manner that the tip portions on the opposite side to the detection unit  10  are led out of the holder  2  from the first and second recessed grooves  301 ,  302  and are connected to the first and second conductive support members  51 ,  52 , work of connecting the first and second lead wires  11 ,  12  to the first and second conductive support members  51 ,  52  can be performed reliably in the state in which the thermistor  1  is held by the holder  2 . 
     (5) It is possible to easily fix the main body member  3  to the first and second conductive support members  51 ,  52  by fitting the first and second conductive support members  51 ,  52  into the first and second fitting holes  321 ,  322  of the main body member  3 . 
     (6) Since the main body member  3  has the partition wall portions  331 ,  332  that separate the ends of the first and second recessed grooves  301 ,  302  from the first and second fitting holes  321 ,  322 , cracks, etc., on the main body member  3  can be prevented from occurring when the first and second conductive support members  51 ,  52  are fitted into the first and second fitting holes  321 ,  322 . 
     (7) Since the detection unit  10  of the thermistor  1  is fixed inside the recess  300  by the curable resin  20 , it is possible to firmly fix the detection unit  10  to the main body member  3 . In addition, since the recess  300  has the bottom-side portion  300   a  along the outline of the sealing body  103  of the detection unit  10  and the opening-side portion  300   b  having a larger inner diameter than the bottom-side portion  300   a , the detection unit  10  is reliably positioned by the bottom-side portion  300   a  and it is possible to ensure that the curable resin  20  spreads around the sealing body  103  in a portion on the opening side relative to the step surface  300   c.    
     (8) Since the lid member  4  has the flat plate portion  40  covering the first and second recessed grooves  301 ,  302  and the first and second recessed grooves  301 ,  302  are formed on the main body member  3  so as to be recessed from the bottom surface  340   a  of the recessed portion  340  which houses the plate portion  40 , the first and second lead wires  11 ,  12  can be reliably prevented from slipping out by the lid member  4 . 
     Summary of the Embodiment 
     Technical ideas understood from the embodiment will be described below citing the reference numerals, etc., used for the embodiment. However, each reference numeral described below is not intended to limit the constituent elements in the claims to the members, etc., specifically described in the embodiment. 
     [1] A physical quantity sensor-fixing structure, comprising: a holder ( 2 ) holding a physical quantity sensor (thermistor  1 ) comprising a detection unit ( 10 ) to detect a physical quantity and a plurality of lead wires ( 11 ,  12 ) connected to the detection unit ( 10 ), the holder ( 2 ) fixing the physical quantity sensor ( 1 ) to a plurality of conductive support members ( 51 ,  52 ) to be respectively connected to the plurality of lead wires ( 11 ,  12 ), wherein the holder ( 2 ) comprises a main body member ( 3 ) comprising a housing portion ( 30 ) to house at least a portion of the physical quantity sensor ( 1 ), and a lid member ( 4 ) covering at least a portion of the housing portion ( 30 ). 
     [2] The physical quantity sensor-fixing structure described in [ 1 ], wherein a recess ( 300 ) to house the detection unit ( 10 ) and a plurality of recessed grooves ( 301 ,  302 ) to house at least respective portions of the plurality of lead wires ( 11 ,  12 ) are formed on the main body member ( 3 ) in such a manner that the recess ( 300 ) is in communication with the plurality of recessed grooves ( 301 ,  302 ). 
     [3] The physical quantity sensor-fixing structure described in [ 2 ], wherein the recess ( 300 ) and the plurality of recessed grooves ( 301 ,  302 ) are open toward a predetermined direction perpendicular to an alignment direction of the plurality of conductive support members ( 51 ,  52 ). 
     [4] The physical quantity sensor-fixing structure described in [ 2 ] or [ 3 ], wherein the plurality of lead wires ( 11 ,  12 ) are arranged in such a manner that tip portions on an opposite side to the detection unit ( 10 ) are led out of the holder ( 2 ) from the plurality of recessed grooves ( 301 ,  302 ), and wherein the respective tip portions of the plurality of lead wires ( 11 ,  12 ) are connected to the plurality of conductive support members ( 51 ,  52 ) outside the holder ( 2 ). 
     [5] The physical quantity sensor-fixing structure described in any one of [ 2 ] to [ 4 ], wherein a plurality of fitting holes ( 321 ,  322 ) to respectively house end portions of the plurality of conductive support members ( 51 ,  52 ) are formed on the main body member ( 3 ), and wherein the main body member ( 3 ) is fixed to the plurality of conductive support members ( 51 ,  52 ) by fitting the plurality of conductive support members ( 51 ,  52 ) into the plurality of fitting holes ( 321 ,  322 ). 
     [6] The physical quantity sensor-fixing structure described in [ 5 ], wherein the main body member ( 3 ) comprises partition wall portions ( 331 ,  332 ) that separate the plurality of fitting holes ( 321 ,  322 ) from ends of the plurality of recessed grooves ( 31 ,  32 ) from which the plurality of lead wires ( 11 ,  12 ) respectively are led out. 
     [7] The physical quantity sensor-fixing structure described in any one of [ 2 ] to [ 6 ], wherein the lid member ( 4 ) covers the plurality of recessed grooves ( 301 ,  302 ), and wherein the detection unit ( 10 ) is fixed inside the recess ( 300 ) by a curable resin ( 20 ). 
     [8] The physical quantity sensor-fixing structure described in any one of [ 2 ] to [ 7 ], wherein the lid member ( 4 ) comprises a flat plate portion ( 40 ) covering the plurality of recessed grooves ( 301 ,  302 ), wherein a recessed portion ( 340 ) to house the plate portion ( 40 ) is formed on the main body member ( 3 ), and wherein the plurality of recessed grooves ( 301 ,  302 ) are formed so as to be recessed from a bottom surface ( 340   a ) of the recessed portion ( 340 ). 
     Although the embodiment of the invention has been described, the invention according to claims is not to be limited to the embodiment described above. Further, please note that not all combinations of the features described in the embodiment are necessary to solve the problem of the invention.