Abstract:
Provided is a vehicle brushless AC generator capable of improving workability and improving insulation property to enhance reliability while preventing a decrease in slot space factor of a stator coil. In the vehicle brushless AC generator, grooves ( 20   a,    20   b ) are formed in an inner wall of a front bracket ( 20 ), and a mold body ( 26 ) for insulating and protecting a lead wire ( 25 ) is mounted into the grooves ( 20   a,    20   b ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a vehicle brushless AC generator to be mounted on a vehicle, such as an automobile, a bus, and a truck. 
         [0003]    2. Description of the Related Art 
         [0004]    In a related-art vehicle brushless AC generator, there is known a structure in which a field coil is mounted in a front bracket and a control circuit unit including a voltage regulator and a rectifier is mounted in a rear bracket so that the control circuit unit may be avoided from being thermally affected by a front-side bearing that generates a large amount of heat (see, for example, Japanese Patent Application Laid-open No. Hei 03-195348). 
         [0005]    As another related art, a lead wire as a lead-out portion of the field coil is connected to the voltage regulator from a conductive wire path formed in a stationary yoke section through a first notch groove formed in an outer peripheral-side inner wall surface of a front frame, a through bolt-use notch groove formed in an outer peripheral surface of a stator core, and a second notch groove formed in an outer peripheral-side inner wall surface of a rear frame (see, for example, Japanese Patent No. 4450134). 
         [0006]    In the related-art vehicle brushless AC generator as disclosed in Japanese Patent Application Laid-open No. Hei 03-195348, a connection bracket for connecting the field coil and the voltage regulator together is mounted while passing through a slot of the stator core, and hence a slot space factor of a stator coil in the stator core may decrease to reduce an output. There is also another problem in that the work of mounting the connection bracket into the narrow slot becomes cumbersome. 
         [0007]    In the related-art vehicle brushless AC generator as disclosed in Japanese Patent No. 4450134, the lead wire of the field coil is provided directly on the notch grooves formed in the respective frames and the stator core, and hence there is a problem in that the lead wire is susceptible to vibration, water, or dust and the coating of the lead wire may be damaged to reduce reliability due to insufficient insulation property. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention has been made to solve the above-mentioned problems, and it is an object thereof to provide a vehicle brushless AC generator capable of improving workability and improving insulation property to enhance reliability while preventing a decrease in slot space factor of a stator coil. 
         [0009]    According to one embodiment of the present invention, there is provided a vehicle brushless AC generator, including: a rotary shaft; a magnetic pole core firmly fixed to the rotary shaft, the magnetic pole core having a magnetic pole; a field coil fixedly mounted on an inner peripheral portion of the magnetic pole core; a yoke section that firmly fixes the field coil to form a magnetic circuit with a bias of the field coil; a bowl-shaped front bracket that firmly fixes the yoke section and is supported by the rotary shaft through intermediation of a front bearing; a stator core arranged to be opposed to the magnetic pole core through intermediation of a minute air gap; a stator coil wound around the stator core; a bowl-shaped rear bracket that firmly fixes the stator core together with the bowl-shaped front bracket and is supported by the rotary shaft through intermediation of a rear bearing; a voltage regulator mounted to the bowl-shaped rear bracket, for controlling an energization current of the field coil; a lead wire having one end connected to the field coil and another end connected to the voltage regulator, the lead wire being arranged at an inner peripheral portion of each of the bowl-shaped front bracket and the bowl-shaped rear bracket; a groove formed in an inner wall of the bowl-shaped front bracket; and a mold body mounted in the groove, for insulating and protecting the lead wire. 
         [0010]    According to one embodiment of the present invention, the lead wire is arranged at the inner peripheral portions of the brackets, and hence the coil space factor in the slot is not decreased unlike the related art, thus improving the output. Further, the lead wire can be mounted in the mold body provided in the groove of the inner wall of the front bracket, and hence the mounting workability is improved. Further, the lead wire is mounted in the groove through intermediation of the mold body, and hence the environment resistance to vibration, water, dust, or the like is improved to obtain sufficient insulation property, thus enhancing the reliability. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a vertical cross-sectional view illustrating a vehicle brushless AC generator according to a first embodiment of the present invention. 
           [0012]      FIG. 2  is an enlarged cross-sectional view illustrating a main portion of  FIG. 1 . 
           [0013]      FIG. 3  is a front view illustrating a front bracket of the vehicle brushless AC generator illustrated in  FIG. 1 . 
           [0014]      FIG. 4  is a front view illustrating a mold body as a main portion of the vehicle brushless AC generator illustrated in  FIG. 1 . 
           [0015]      FIG. 5  is a rear view illustrating the mold body as the main portion of the vehicle brushless AC generator illustrated in  FIG. 1 . 
           [0016]      FIG. 6  is a cross-sectional view taken along the line A-A of  FIG. 4 . 
           [0017]      FIG. 7  is an enlarged view of the portion Q illustrated in  FIG. 6 . 
           [0018]      FIG. 8  is an enlarged view of the portion P illustrated in  FIG. 4 . 
           [0019]      FIG. 9  is a cross-sectional view taken along the line B-B of  FIG. 5 . 
           [0020]      FIG. 10  is a cross-sectional view taken along the line C-C of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     First Embodiment 
       [0021]      FIG. 1  is a vertical cross-sectional view illustrating a vehicle brushless AC generator according to a first embodiment of the present invention.  FIG. 2  is an enlarged cross-sectional view illustrating a main portion of  FIG. 1 .  FIG. 3  is a front view illustrating a front bracket of  FIG. 1 .  FIG. 4  is a front view illustrating a mold body as a main portion of the vehicle brushless AC generator illustrated in  FIG. 1 .  FIG. 5  is a rear view illustrating the mold body as the main portion of the vehicle brushless AC generator illustrated in  FIG. 1 .  FIG. 6  is a cross-sectional view taken along the line A-A of  FIG. 4 .  FIG. 7  is an enlarged view of the portion Q illustrated in  FIG. 6 .  FIG. 8  is an enlarged view of the portion P illustrated in  FIG. 4 .  FIG. 9  is a cross-sectional view taken along the line B-B of  FIG. 5 .  FIG. 10  is a cross-sectional view taken along the line C-C of  FIG. 5 . 
         [0022]    Referring to  FIGS. 1 to 3 , a rotor  2  is provided to a rotary shaft  17 , and further, the rotor  2  has a magnetic pole core  3  for transferring a magnetic flux. The magnetic pole core  3  includes a first magnetic pole core  4  and a second magnetic pole core  8 . In a first boss section  5  of a rotary member of the first magnetic pole core  4 , a through hole for inserting the rotary shaft  17  therethrough is formed at an axial center position. A ring-shaped fixed yoke section  6  firmly fixed to a bowl-shaped front bracket  20  is arranged on a radially outer side of the first boss section  5  through intermediation of a minute air gap. A field coil  13  is fixed at an axial end portion of the yoke section  6  through intermediation of a plate  31  and a bobbin  32 . Further, a first claw-shaped magnetic pole section  7  is arranged on a radially outer side of the yoke section  6  through intermediation of a minute air gap. The first claw-shaped magnetic pole section  7  is firmly fixed to a second claw-shaped magnetic pole section  11  through intermediation of a ring  12  as a non-magnetic member, and is arranged so as to be engaged with the second claw-shaped magnetic pole section  11 . Note that, the rotary shaft  17  is press-fitted into a through hole formed at an axial center of the first magnetic pole core  4 , and is mounted thereto in a relatively unrotatable manner. In a second boss section  9  of the second magnetic pole core  8 , on the other hand, an insertion hole for inserting the rotary shaft  17  therethrough is formed at an axial center position similarly to the first magnetic pole core  4 . A yoke section  10 , which is a ring-shaped rotary member, extends from one end of the second boss section  9  to the radially outer side, and further, the second claw-shaped magnetic pole section  11  extends from an outer periphery of the yoke section  10  toward the other axial end. 
         [0023]    Note that, the rotary shaft  17  is press-fitted into an insertion hole formed at an axial center of the second magnetic pole core  8 , and is mounted thereto in a relatively unrotatable manner under a state in which an axial end surface of the second boss section  9  abuts on the other axial end surface of the first boss section  5 . 
         [0024]    In addition, a stator  14  includes a stator core  15  having a stator coil  16  wound therearound, and is arranged so as to surround an outer periphery of the rotor  2 . The front bracket  20  sandwiches the stator core  15  together with a rear bracket  21  with through bolts  23  across shoulder portions of both axial ends of the stator core  15 . Then, the front bracket  20  rotatably supports one end side of the rotary shaft  17  through intermediation of a front bearing  18 , and the rear bracket  21  rotatably supports the other end side of the rotary shaft  17  through intermediation of a rear bearing  19 . In this manner, the rotor  2  is rotatably arranged in the front bracket  20  and the rear bracket  21 . A cooling fan  33  is firmly fixed to the rotary shaft  17  on the outer side of the front bracket  20 . Further, a pulley  24  is firmly fixed at one end of the rotary shaft  17  extending from the front bracket  20  to the outside, and is driven by an engine (not shown). 
         [0025]    A voltage regulator  22  for controlling an energization current of the field coil  13  is mounted outside the rear bracket  21 . A resin cover  29  is firmly fixed to the rear bracket  21  so as to surround the voltage regulator  22  and a rectifier  30 . A plurality of intake holes  29   a  for introducing a cooling air are formed in the resin cover  29 . A lead wire  25  for connecting the voltage regulator  22  and the field coil  13  together is arranged at inner peripheral portions of both the brackets  20  and  21 . One end of the lead wire  25  is connected to the field coil  13 , and the other end thereof is connected to the voltage regulator  22 . A first insulating tube  28 , which is formed of an impregnated resin substantially over its overall length, is mounted around an outer periphery of the lead wire  25 . A receiving groove  20   a,  which is a square recess portion, is formed in aside inner wall of the front bracket  20 . Further, a receiving groove  20   b,  which is a recess having an arc-shaped cross section, is formed in an inner wall of the front bracket  20  on the side on which the stator core  15  is mounted. Then, a mold body  26  for insulating and protecting the lead wire  25  is fitted into the receiving grooves  20   a  and  20   b.  A part of the mold body  26  to be fitted into the receiving groove  20   a  is formed into a square shape, and a part of the mold body  26  to be fitted into the receiving groove  20   b  is formed into a cylindrical shape. Those parts are positioned and received in the respective grooves  20   a  and  20   b.    
         [0026]    The cooling fan  33 , which is an external centrifugal fan and firmly fixed to the rotary shaft  17 , is provided between the outer side of the front bracket  20  and the pulley  24 . A plurality of ventilation holes  20   c  and  21   c  are formed in the front bracket  20  and the rear bracket  21 , respectively. When the cooling fan  33  is rotated, a cooling air is circulated from the intake air  29   a  of the cover  29  to the radially outer side while passing through the ventilation holes  21   c  of the rear bracket  21 , the space between the claw-shaped magnetic pole sections  7  and  11 , an inner peripheral surface of the stator coil  16 , and the ventilation holes  20   c  of the front bracket  20 . 
         [0027]    Next, the mold body  26  is described in more detail with reference to  FIGS. 4 to 10 . 
         [0028]    As illustrated in  FIG. 6 , the mold body  26  is formed into a substantially inverted L-shape in cross section, and is integrally molded with a resin so that the lead wire  25  may be mounted therein. 
         [0029]    At one end portion of the mold body  26  to be fixed to the yoke section  6 , a protrusion portion  26   e  to be fitted into the through hole of the yoke section  6  is provided. A through hole  26   g  for inserting the lead wire  25  therethrough is formed in the protrusion portion  26   e.    
         [0030]    At an outer peripheral portion of the protrusion portion  26   e,  projections  26   f  are equiangularly formed at three positions. With the projections  26   f,  the mold body  26  can be fixedly positioned at the yoke section  6  reliably. 
         [0031]    The mold body  26  further includes a mounting portion  26   a  that has a square cross section and opens on one side so as to be fitted into the groove  20   a  of the front bracket  20 , and sandwiching portions  26   b  for sandwiching the lead wire  25  to prevent the lead wire  25  from protruding out of the mold body  26 . 
         [0032]    A cylindrical portion  26   c  to be fitted into the groove  20   b,  which is formed in the front bracket  20  on the side on which the stator core is mounted, extends in the axial direction, and a flange portion  26   d  is provided at an end portion of the cylindrical portion  26   c.    
         [0033]    A through hole  26   h  for inserting the lead wire  25  therethrough is formed in the cylindrical portion  26   c.    
         [0034]    The flange portion  26   d  is fitted between both the brackets  20  and  21  and fixed reliably. 
         [0035]    A through hole  21   a  for inserting and holding the lead wire  25  therethrough is formed in the inner peripheral portion of the rear bracket  21 . The through hole  21   a  is circular in cross section, and the inner diameter thereof is set to be larger than a lead wire diameter so that the lead wire  25  may be inserted therethrough. On most part of the lead wire  25  to be mounted in the receiving grooves  20   a  and  20   b  and the through hole  21   a,  a second tube  27  made of a silicon tube is mounted around an outer periphery of the first tube  28 . In addition, the end of the lead wire  25  on the field coil  13  side is connected to the field coil  13  through a through hole formed in an inner peripheral portion of the yoke section  6 . 
         [0036]    In the vehicle brushless AC generator configured in this way, when a current is supplied to the field coil  13  from a battery (not shown), a magnetic flux cp is generated around the field coil  13 . The magnetic flux cp flows in the following path. The magnetic flux cp is transferred from the yoke section  6  to the first boss section  5  through the minute air gap formed on the radially inner side, and is then transferred from the second boss section  9  whose end surface abuts on the first boss section  5  to pass through the yoke section  10  and the second claw-shaped magnetic pole section  11 , and to cross the stator  14  arranged on the radially outer side of the rotor  2 . The magnetic flux cp subsequently passes through the first claw-shaped magnetic pole section  7  and the minute air gap formed on the radially inner side thereof, and finally returns to the yoke section  6 . Thus, the second claw-shaped magnetic pole section  11  is magnetized to the N pole, and the first claw-shaped magnetic pole section  7  is magnetized to the S pole. 
         [0037]    On the other hand, when the pulley  24  is driven by the engine, the rotary shaft  17  coupled directly to the pulley  24  is rotated to rotate the rotor  2 . Through the rotation of the rotor  2 , a magnetic field generated by the field coil  13  is also rotated. The magnetic flux cp forming the rotating magnetic field flows in the above-mentioned path to be applied to the stator core  15 , to thereby generate an AC electromotive force in the stator coil  16 . With the AC electromotive force, an AC current generated in the stator coil  16  is rectified into a DC current by the rectifier  30 , and the battery (not shown) is charged. In this case, the field coil  13  is not rotated because the field coil  13  is mounted on the yoke section  6  firmly fixed to the front bracket  20 , but the first boss section  5  and the first claw-shaped magnetic pole section  7  of the first magnetic pole core  4  and the second magnetic pole core  8  integrally including the second boss section  9 , the yoke section  10 , and the second claw-shaped magnetic pole section  11  are rotated. 
         [0038]    According to the first embodiment, the lead wire  25  is inserted through the mold body  26 , and hence the lead wire  25  can be fixedly held and can be protected from the rotor  2  electrically and mechanically. The mold body  26  can be mounted on each of the brackets  20  and  21  through the receiving grooves  20   a  and  20   b  formed in the front bracket  20  and the through hole  21   a  formed in the rear bracket  21 . Consequently, the mold body  26  can be prevented from falling off even when vibrated, and can be sufficiently protected from water and dust. Besides, the positioning of the mold body  26  is facilitated, and hence the lead wire  25  can be fixed to each of the brackets  20  and  21  reliably and easily. 
         [0039]    The flange portion  26   d  of the mold body  26  is fixedly sandwiched between both the brackets  20  and  21 . Consequently, the mold body  26  can be fixedly held reliably. Besides, the work of fixing the lead wire  25  with an adhesive or the like is eliminated, and hence the workability is improved. 
         [0040]    A fixing method using an adhesive or the like has a problem in that the adhesive may peel off in actual use and the rotor  2  and the lead wire  25  may be brought into contact with each other. However, the fixing means according to the present invention can solve this problem. 
         [0041]    In addition, the lead wire  25  is inserted through the mold body  26  and the double tubes  27  and  28 , and hence the exposed area of the lead wire  25  can be reduced to further reduce the influence of water, dust, and the like. 
         [0042]    Besides, the lead wire  25  is inserted through the through hole  21   a  of the rear bracket  21  in order to be connected to the voltage regulator  22  mounted outside the rear bracket  21 , and hence the lead wire  25  can be connected to the voltage regulator  22  with very small dimensions, and further, can be protected and led out reliably. 
         [0043]    Note that, the structure in which the double tubes  27  and  28  are mounted around the lead wire  25  has been exemplified in the above-mentioned embodiment, but only one tube  28  may be mounted. 
         [0044]    Further, the structure in which the part of the lead wire  25  on the field coil  13  side is led out from the inner peripheral portion of the yoke section  6  has been exemplified, but the part of the lead wire  25  on the field coil  13  side may be led out from an outer peripheral portion of the yoke section  6 . 
         [0045]    Note that, the structure in which the voltage regulator  22  is mounted outside the rear bracket  21  has been exemplified in the above-mentioned embodiment, but the present invention is not limited thereto. The voltage regulator  22  may be mounted inside the rear bracket  21 . In this case, instead of forming the through hole  21   a,  a receiving groove may be formed in an inner wall of the rear bracket  21 , and the lead wire  25  may be received directly in the groove. Further, when the lead wire  25  is received in the groove through the intermediation of the mold body similarly to the mold body  26 , the lead wire  25  can be protected more reliably. 
         [0046]    Further, the claw-shaped magnetic pole has been exemplified above as a rotating magnetic pole, but the present invention is not limited thereto.