Abstract:
Provided is a rotating electric machine capable of suppressing an increase in temperature of an output terminal ( 26 ) to suppress a temperature rise of an internal device, and preventing lowering of a force for fastening the output terminal and a terminal portion of an external device. The rotating electric machine for a vehicle includes a rectifier provided inside a casing, and a terminal device projecting outward through an opening portion of the casing to connect the internal device and the external device. The terminal device includes the output terminal ( 26 ) projecting outward through the opening portion to be connected to the terminal portion of the external device by fastening, and a resin body ( 37 ) having electrical insulating property and high thermal conductivity, for integrally covering the output terminal ( 26 ) except at least for a portion to be connected to a harness-side terminal ( 35 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a rotating electric machine including a terminal device for electrically connecting an external device provided outside a casing to an internal device provided inside the casing. 
         [0003]    2. Description of the Related Art 
         [0004]    In a related-art AC generator for a vehicle, an output terminal projects in a radial direction of a rear bracket. A terminal electrically connected to a harness on a vehicle side is inserted into the output terminal and is securely fastened by a nut. In this manner, power of the AC generator for a vehicle is output to a device on the vehicle side. 
         [0005]    In recent years, as an output of the AC generator for a vehicle, a high output equal to or higher than 200 A is required. Therefore, such a high current flows through the output terminal. The output terminal is generally firmly fixed integrally with an insulating bush made of a resin and is mounted to a heat sink of a rectifier or the like (see, for example, Japanese Patent No. 3974560). 
         [0006]    The related-art AC generator described above has a problem in that the output terminal generates heat by a flow of the high current to cause a rise in temperature of semiconductor elements such as diodes constituting the rectifier provided in proximity to the output terminal. 
         [0007]    Moreover, there is another problem. Specifically, the heat generation of the output terminal leads to thermal deterioration and thermal contraction of the insulating bush made of a resin. As a result, the fastened nut is loosened to lower a force applied by the nut for fastening the harness-side terminal to the output terminal. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention has been made to solve the problems described above, and therefore has an object to provide a rotating electric machine capable of suppressing an increase in temperature of an output terminal to suppress a temperature rise of an internal device provided inside a casing, and preventing lowering of a force for fastening the output terminal and a terminal portion of an external device to each other. 
         [0009]    According to one embodiment of the present invention, there is provided a rotating electric machine, including:
       a casing having an opening portion;   an internal device provided inside the casing; and   a terminal device provided so as to project outward from inside of the casing through the opening portion, the terminal device being configured to electrically connect the internal device and an external device provided outside the casing,   in which the terminal device includes:
           an output terminal projecting outward through the opening portion to be connected to a terminal portion of the external device by fastening; and   a resin body having electrical insulating property and high thermal conductivity, for integrally covering the output terminal except at least for a portion to be connected to the terminal portion.   
               
 
         [0016]    Further, according to another embodiment of the present invention, there is provided a rotating electric machine, including:
       a casing having an opening portion;   an internal device provided inside the casing; and   a terminal device provided so as to project outward from inside of the casing through the opening portion, the terminal device being configured to electrically connect the internal device and an external device provided outside the casing,   in which the terminal device includes:
           an output terminal projecting outward through the opening portion to be connected to a terminal portion of the external device by fastening;   a cylindrical body having electrical insulating property and high thermal conductivity, the cylindrical body including:
               a joint portion joined to an outer circumferential portion of a part of the output terminal, the part being connected to the internal device;   a base portion extending from the joint portion in a radial direction of the cylindrical body; and   an extended portion having a larger diameter than a diameter of the joint portion and extending from the base portion in an axial direction of the cylindrical body so as to surround the output terminal;   
               a heat sink jointed to an outer circumferential portion of the extended portion of the cylindrical body; and   a resin body having electrical insulating property and high thermal conductivity, the resin body being provided so as to surround the output terminal, the resin body integrating the output terminal, the cylindrical body, and the heat sink with each other.   
               
 
         [0028]    According to the rotating electric machine of one embodiment of the present invention, the output terminal is covered integrally with the resin body having the electrical insulating property and the high thermal conductivity except at least for the portion to be connected to the terminal portion. Therefore, with a simple configuration, an increase in temperature of the output terminal can be suppressed to suppress a temperature rise of the internal device provided inside the casing. Further, the force for fastening the output terminal and the terminal portion of the external device to each other can be prevented from being lowered. 
         [0029]    Further, according to the rotating electric machine of another embodiment of the present invention, the resin body having the electrical insulating property and the high thermal conductivity is provided so as to surround the output terminal. In addition, the output terminal, the cylindrical body, and the heat sink are integrated with each other by using the resin body. Thus, the increase in temperature of the output terminal can be further suppressed. As a result, the temperature rise of the internal device provided inside the casing can be suppressed. Further, the force for fastening the output terminal and the terminal portion of the external device to each other can be prevented from being lowered. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0030]      FIG. 1  is a vertical sectional view illustrating an AC generator for a vehicle according to a first embodiment of the present invention. 
           [0031]      FIG. 2  is an enlarged sectional view of a main part of  FIG. 1 . 
           [0032]      FIG. 3  is a plan view of  FIG. 2 . 
           [0033]      FIG. 4  is a vertical sectional view illustrating an AC generator for a vehicle according to a second embodiment of the present invention. 
           [0034]      FIG. 5  is an enlarged sectional view of a main part of  FIG. 4 . 
           [0035]      FIG. 6  is a plan view of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    Now, embodiments of the present invention are described referring to the accompanying drawings. In the drawings, the same or corresponding members and parts are denoted by the same reference symbols. 
       First Embodiment 
       [0037]      FIG. 1  is a vertical sectional view illustrating an AC generator for a vehicle according to a first embodiment of the present invention,  FIG. 2  is an enlarged sectional view of a main part of  FIG. 1 , and  FIG. 3  is a plan view of  FIG. 2 . 
         [0038]    An AC generator  1  for a vehicle, which is a rotating electric machine, includes a casing  4 , a shaft  6 , a pulley  7 , a rotor  8 , a pair of fans  11 , and a stator  12 . The casing  4  includes a front bracket  2  and a rear bracket  3 , each being made of aluminum to have an approximately bowl-like shape. The shaft  6  is rotatably supported by the casing  4  through a pair of bearings  5 . The pulley  7  is firmly fixed to an axial end portion of the shaft  6 , which extends to a front side of the casing  4 . The rotor  8  is fixed to the shaft  6  and is provided in the casing  4 . The fans  11  are respectively fixed to both axial end surfaces of the rotor  8 . The stator  12  is fixed to the casing  4  so as to surround the rotor  8 . 
         [0039]    The AC generator  1  for a vehicle further includes a pair of slip rings  15 , a pair of brushes  16 , a brush holder  17 , a voltage regulator  19 , and a rectifier  20 . The slip rings  15  for supplying a current to the rotor  8  are each fixed to a portion of the shaft  6 , which is extended to a rear side of the casing  4 . The brushes  16  come into sliding contact with surfaces of the respective slip rings  15 . The brush holder  17  receives the pair of brushes  16  therein. The voltage regulator  19  is mounted to a surface of the brush holder  17 , which is located on the rear bracket  3  side, and regulates a magnitude of an AC voltage generated in stator windings  14  described below, which are provided to the stator  12 . The rectifier  20  is provided in a rear-side space inside the rear bracket  3  and converts an AC electromotive force generated in the stator  12  into a DC output voltage. 
         [0040]    The rotor  8  is a Lundell-type rotor. The rotor  8  includes field windings  9  and pole cores  10 . An exciting current flows through the field windings  9  to generate magnetic fluxes. The pole cores  10  are provided so as to cover the field windings  9 . Magnetic poles are formed in the pole cores  10  by the magnetic fluxes generated by the field windings  9 . 
         [0041]    The stator  12  includes a stator core  13  having a cylindrical shape and the stator windings  14 . The stator windings  14  are wound around the stator core  13  and induce the AC electromotive force by a change in magnetic flux from the field windings  9  along with the rotation of the rotor  8 . 
         [0042]    The stator core  13  of the stator  12 , which is provided so as to surround the rotor  8 , is provided between an open end of the front bracket  2  and an open end of the rear bracket  3 . The stator core  13  is interposed between the front bracket  2  and the rear bracket  3  by fastening the front bracket  2  and the rear bracket  3  provided on both axial ends of the stator core  13  with a plurality of bolts. 
         [0043]    The rectifier  20  includes a positive-pole side heat sink  21 , a negative-pole side heat sink  22 , and a circuit board  23 . The positive-pole side heat sink  21  has an approximately C-like shape as viewed from an axial direction of the shaft  6 . A plurality of positive-pole side fins  21   a , which extend outward in the axial direction of the shaft  6 , are provided on one surface of the positive-pole side heat sink  21 , whereas a plurality of positive-pole side rectifier elements (not shown) are mounted on another surface of the positive-pole side heat sink  21 . The negative-pole side heat sink  22  has an approximately C-like shape as viewed from the axial direction of the shaft  6  and is provided so as to overlap the positive-pole side heat sink  21  in the axial direction of the shaft  6 . On the negative-pole side heat sink  22 , a plurality of negative-pole side rectifier elements (not shown) are mounted. The circuit board  23  has an approximately C-like shape as viewed from the axial direction of the shaft  6  and retains the positive-pole side heat sink  21  and the negative-pole side heat sink  22 . 
         [0044]    For the positive-pole side heat sink  21  and the negative-pole side heat sink  22 , a material having high thermal conductivity such as aluminum is used. For the circuit board  23 , a resin such as polyphenylene sulfide is used. 
         [0045]    The positive-pole side heat sink  21 , the negative-pole side heat sink  22 , and the circuit board  23  are fastened to the rear bracket  3  by a mount screw (not shown). 
         [0046]    Next, a terminal device of the AC generator  1  for a vehicle is described referring to  FIGS. 2 and 3 . 
         [0047]    The terminal device includes an output terminal  26 , a cylindrical body  30 , a heat sink  31 , and a resin body  32 . The cylindrical body  30  has an end portion joined to the output terminal  26 . The heat sink  31  is joined onto an outer circumferential portion of the cylindrical body  30 . The resin body  32  has electrical insulating property and high thermal conductivity. The resin body  32  surrounds the output terminal  26  and integrates the output terminal  26 , the cylindrical body  30 , and the heat sink  31  with each other. 
         [0048]    The terminal device is mounted to a relay terminal bolt  25  provided inside the rear bracket  3 . 
         [0049]    The relay terminal bolt  25  is made of an electrically conductive material such as iron. The relay terminal bolt  25  includes a head portion  25   a  and an output-terminal mounting male screw  25   c . The head portion  25   a  has a knurled portion  25   b , which is formed by knurling a bottom portion (small-diameter portion) of the head portion  25   a . The relay terminal bolt  25  is mounted to one of flange portions  24  provided on both ends of the positive-pole side heat sink  21  by press-fitting the knurled portion  25   b  into a through hole  24   a  formed through the one flange portion  24 . 
         [0050]    The output terminal  26  of the terminal device is made of an electrically conductive material such as iron. The output terminal  26  includes a coupling seat  27 , a harness-side terminal mounting male screw portion  28 , and a mounting portion  29 . The harness-side terminal mounting male screw portion  28  is provided on one side of the coupling seat  27  so as to be extended therefrom. The mounting portion  29  is provided on another side of the coupling seat  27  so as to be extended therefrom. A through hole  29   a  is formed through a distal end portion of the mounting portion  29 . 
         [0051]    The output terminal  26  is securely fastened to the one flange portion  24  of the positive-pole side heat sink  21  by inserting the output-terminal mounting male screw  25   c  into the through hole  29   a  and then screwing an output-terminal mounting nut  33  onto the output-terminal mounting male screw  25   c.    
         [0052]    The cylindrical body  30  includes a joint portion  30   a , a base portion  30   b , and an extended portion  30   c . The joint portion  30   a  has a cylindrical shape and extends inward from the coupling seat  27  of the output terminal  26  in a radial direction of the shaft  6  to be joined to the output terminal  26 . The base portion  30   b  extends from the joint portion  30   a  in a radial direction of the cylindrical body  30 . The extended portion  30   c  having a larger diameter than that of the joint portion  30   a  extends from the base portion  30   b  in an axial direction of the cylindrical body  30 . The cylindrical body  30  is made of a ceramic having electrical insulating property and high thermal conductivity. 
         [0053]    The heat sink  31  made of aluminum is mounted integrally to an outer circumferential portion of the extended portion  30   c  of the cylindrical body  30 . The heat sink  31  includes a plurality of, for example, thirty-four cooling fins  31  a, which are provided equiangularly to the heat sink  31 . 
         [0054]    The resin body  32  includes a terminal portion  32   a , a base portion  32   b , and a mounting portion  32   c . The terminal portion  32   a  is integral with the extended portion  30   c  of the cylindrical body  30  and is separated away from the output terminal  26 . The base portion  32   b  is integral with the base portion  30   b  of the cylindrical body  30 . The mounting portion  32   c  is integral with the joint portion  30   a  of the cylindrical body  30 . The resin body  32  integrates the output terminal  26 , the cylindrical body  30 , and the heat sink  31  by insert molding. 
         [0055]    In the manner described above, the terminal device including the output terminal  26 , the cylindrical body  30 , the heat sink  31 , and the resin body  32  is constructed as a single component. 
         [0056]    In this embodiment, the resin body  32  is made of a thermoplastic polyphenylene sulfide (PPS) resin. 
         [0057]    An opening portion of the mounting portion  32   c  of the resin body  32  is closed by a cap  34  as illustrated in  FIG. 1 . 
         [0058]    A harness-side terminal  35 , which is a terminal portion of an external device, is securely fastened to the coupling seat  27  with a harness-side terminal mounting nut  36  screwed onto the harness-side terminal mounting male screw portion  28 . 
         [0059]    An opening portion  3   a  is provided to the rear bracket  3  located on the outer side of the rectifier  20  so as to be formed at a position corresponding to the rectifier  20  in the radial direction of the shaft  6 . The output terminal  26 , which is integral with the cylindrical body  30 , the heat sink  31 , and the resin body  32 , projects outward in the radial direction of the shaft  6  through the opening portion  3   a  from the inside of the rear bracket  3 . 
         [0060]    The terminal portion  32   a  of the resin body  32 , which projects in the radial direction of the shaft  6 , includes a pair of cutout portions  32   d  formed on a circumference so that the cutout portions  32   d  are opposed to each other, as illustrated in  FIG. 3 . The harness-side terminal  35  can be inserted through any one of the cutout portions  32   d . Moreover, at the time of fastening with the nut  36 , the cutout portions  32   d  have a function of retaining the harness-side terminal  35 . As a result, the fastening is facilitated. 
         [0061]    In the thus constructed AC generator  1  for a vehicle, a current is supplied from a battery (not shown) through the brushes  16  and the slip rings  15  to the field windings  9  to generate the magnetic fluxes. 
         [0062]    By the magnetic fluxes, magnetic poles of one of the pole cores  10  are magnetized to the N-pole, whereas magnetic poles of another pole core  10  are magnetized to the S-pole. 
         [0063]    On the other hand, a rotating torque of an engine is transmitted through an intermediation of a belt (not shown) and the pulley  7  to the shaft  6  to rotate the rotor  8 . As a result, a rotating magnetic field is applied to the stator windings  14  to generate the electromotive force in the stator windings  14 . The AC electromotive force is rectified into a direct current through the rectifier  20 , while a magnitude of the DC voltage is regulated by the voltage regulator  19 . Then, an output of the rectifier  20  passes through the relay terminal bolt  25 , the output terminal  26 , and the harness-side terminal  35  to charge the battery. 
         [0064]    According to the AC generator  1  for a vehicle of the first embodiment of the present invention, an output current of about 200 A at a maximum flows through the output terminal  26 . Heat generation by the energization with the current flow is transmitted to the base portion  30   b  and the extended portion  30   c  through the joint portion  30   a  of the cylindrical body  30  so as to be radiated from the cooling fins  31  a of the heat sink  31 . 
         [0065]    In this manner, a temperature rise of the output terminal  26  and the resin body  32  can be suppressed. As a result, a temperature rise of the relay terminal bolt  25  and the positive-pole side heat sink  21  is also suppressed. Thus, a temperature rise of the diodes mounted to the positive-pole side heat sink  21  is also suppressed. Accordingly, thermal deterioration is prevented, and durability is improved. 
         [0066]    Further, an increase in temperature of the resin body  32  can also be suppressed. Therefore, thermal deterioration and thermal contraction of the resin body  32  can be prevented, and a force applied by the nut  36  for fastening the harness-side terminal  35  to the output terminal  26  can be prevented from being lowered. 
         [0067]    Further, the output terminal  26 , the cylindrical body  30 , the heat sink  31 , and the resin body  32  are constructed as the single component. Thus, the number of components is reduced. Moreover, excellent ease of assembly is obtained. 
         [0068]    When a space between the joint portion  30   a  of the cylindrical body  30  and the output terminal  26  is filled with a silicon resin having high thermal conductivity, heat radiating performance of the output terminal  26  is further improved. As a result, the temperature rise of the output terminal  26  and the resin body  32  can be further suppressed. 
         [0069]    Alternatively, when the space between the joint portion  30   a  of the cylindrical body  30  and the output terminal  26  is filled with an adhesive having high thermal conductivity in place of the silicon resin, joint strength between the output terminal  26  and the cylindrical body  30  can be improved in addition to the improvement of the heat radiating performance of the output terminal  26 . 
         [0070]    Further alternatively, the space may be filled with a silicon resin mixed with an adhesive. 
         [0071]    The heat sink  31  made of aluminum may be formed by extrusion. 
         [0072]    Moreover, the heat sink  31  may also be formed by die-cast molding because the plurality of cooling fins  31   a  are formed. 
         [0073]    Although the cylindrical body  30  made of the ceramic has been described by way of example, any material having electrical insulating property and high thermal conductivity may be used. 
         [0074]    Further, although the heat sink  31  made of aluminum has been described by way of example, other materials having high thermal conductivity, such as copper, may also be used. 
         [0075]    Further, the heat sink  31  provided with the cooling fins  31   a  has been described by way of example. However, when the heat sink  31  itself is formed into, for example, a lattice pattern or a net-like pattern to be exposed externally, the heat radiating performance can be ensured even without the cooling fins  31   a.    
       Second Embodiment 
       [0076]      FIG. 4  is a vertical sectional view illustrating an AC generator  1  for a vehicle according to a second embodiment of the present invention,  FIG. 5  is a view of a main part of  FIG. 4 , and  FIG. 6  is a plan view of  FIG. 5 . 
         [0077]    In the second embodiment, a resin body  37  is made of a thermoplastic resin mixed with an inorganic filler having high thermal conductivity. The resin body  37  is formed integrally with the output terminal  26  by insert molding. 
         [0078]    The resin body  37  includes a terminal portion  37   a , a base portion  37   b , and a mounting portion  37   c . The terminal portion  37   a  is separated away from the output terminal  26 . The base portion  37   b  is integral with the coupling seat  27 . The mounting portion  37   c  is integral with an end portion of the output terminal  26 , which is located on the relay terminal bolt  25  side. 
         [0079]    The terminal portion  37   a , which is located outside the rear bracket  3  in the radial direction of the shaft  6 , has a pair of cutout portions  37   d  formed on a circumference so that the cutout portions  37   d  are opposed to each other, as illustrated in  FIG. 6 . A plurality of (for example, thirty-four) cooling fins  38  are formed on a circumference of an outer circumferential portion of the resin body  37  so as to be integral therewith. 
         [0080]    In the second embodiment, the thermoplastic resin used for the resin body  37  is a PPS resin as in the case of the resin body  32  of the first embodiment. The filler is a metal such as alumina. 
         [0081]    The remaining configuration is the same as that of the AC generator  1  for a vehicle according to the first embodiment. 
         [0082]    According to the AC generator  1  for a vehicle of the second embodiment, the resin body  37  formed integrally with the output terminal  26  is made of the material having the electrical insulating property and the high thermal conductivity. In addition, the plurality of cooling fins  38  are provided on the outer circumferential portion of the resin body  37 . Therefore, heat generated from the output terminal  26  is radiated externally through the resin body  37 . 
         [0083]    In this manner, a temperature rise of the output terminal  26  and the resin body  37  can be suppressed. As a result, a temperature rise of the relay terminal bolt  25  and the positive-pole side heat sink  21  is also suppressed. Thus, a temperature rise of the diodes mounted to the positive-pole side heat sink  21  is also suppressed. Accordingly, thermal deterioration of the diodes is prevented, and durability is improved. 
         [0084]    Further, an increase in temperature of the resin body  37  can also be suppressed. Therefore, thermal deterioration and thermal contraction of the resin body  37  can be prevented, and a force applied by the nut  36  for fastening the harness-side terminal  35  to the output terminal  26  can be prevented from being lowered. 
         [0085]    Further, the output terminal  26  is formed integrally with the resin body  37  by the insert molding. In addition, the cylindrical body  30  and the heat sink  31  of the first embodiment are omitted. Therefore, the manufacturing is further facilitated. 
         [0086]    In the second embodiment described above, the cooling fins  38  are provided on the outer circumferential portion of the resin body  37 . Depending on the kind of filler having high thermal conductivity to be mixed in the thermoplastic resin, however, sufficiently high heat radiating performance can be ensured even without the cooling fins  38 . 
         [0087]    Moreover, by using the resin body  37  of the second embodiment in place of the resin body  32  of the first embodiment, the temperature rise of the output terminal  26  of the first embodiment can be further suppressed. 
         [0088]    Although the output terminal  26  projects outward in the radial direction of the shaft  6  from the opening portion  3   a  of the rear bracket  3  in the first and second embodiments, the output terminal  26  may project from the rear bracket  3  in the axial direction of the shaft  6 . 
         [0089]    Moreover, an output-terminal bolt having a hexagonal head portion may be used for the output terminal  26 . 
         [0090]    Further, the present invention is applied to the terminal device of the AC generator  1  for a vehicle, which is a rotating electric machine, in the first and second embodiments described above. However, as a matter of course, the present invention is not limited thereto, but may also be applicable to, for example, a motor generator serving both as a starter motor and as an AC generator. 
         [0091]    Further, the casing including the front bracket  2  and the rear bracket  3  has been described by way of example in each of the embodiments described above. However, casing may also be a resin case mounted to the rear bracket  3 . 
         [0092]    In this case, the voltage regulator  19  and the rectifier  20  are provided outside the rear bracket  3 . The resin case is mounted to the rear bracket  3  so as to surround the voltage regulator  19  and the rectifier  20 . 
         [0093]    Further, the mounting portion  29  of the terminal device is connected to the positive-pole side heat sink  21  of the rectifier  20 , whereas the output terminal  26  of the terminal device projects outward through an opening portion of the resin case so as to be connected to the terminal of the external device by fastening.