Claims:
1. A starter comprising:
a yoke (4) that forms a magnetic circuit;
an armature (7) that is fixed on a rotor shaft (8) and generates rotation torque based on magnetic flux from the yoke (4);
a commutator (9) that is provided on the rotor shaft (8) and that changes a direction of an electric current supplied from a power source and then supplies the electric current to the armature (7);
a brush (10) that makes slidable contact with an outer circumferential surface of the commutator (9);
a spring (12) that has elastic force for pressing the brush (10) to the outer circumferential surface of the commutator (9),
a brush holder (131, 132, 133, 134) that contains the brush (10) and the spring (12); and
a base member (14) having a brush-holder mounting portion (141, 142, 143, 144) in which the brush holder (131, 132, 133, 134) is mounted, the starter (100) starting an internal combustion engine through torque generated in the armature (7),
wherein the brush-holder mounting portion (141, 142, 143, 144) has a first rail portion (14c) that extends in a radial direction of the commutator (9) and slidably engages with the brush holder (131, 132, 133, 134) in the radial direction,
a second rail portion (14a) that extends in the radial direction of the commutator ((9), that is disposed at an upstream side of the first rail portion (14c) in a rotation direction of the commutator (9), and that slidably engages with the brush holder (131, 132, 133, 134) in the radial direction, and
a locking portion (14b) that engages with the brush holder 131, 132, 133, 134) so as to prevent the brush holder (131, 132, 133, 134) from traveling toward the outside in the radial direction, when the brush holder (131, 132, 133, 134) engages with the first rail portion (14c) and the second rail portion (14a) so as to be mounted at a predetermined position in the brush-holder mounting (141, 142, 143, 144) portion,
wherein the brush holder (131, 132, 133, 134) mounted in the brush-holder mounting portion (141, 142, 143, 144) abuts on the locking portion (14b) by being pressed toward the outside in the radial direction, based on elastic force of the spring.

2. The starter according to claim 1, wherein an inner end portion of the first rail portion (14c) in the radial direction is provided more inside in the radial direction than an inner end portion of the second rail portion (14a) in the radial direction is.

3. The starter according to any one of claims 1 and 2, wherein an outer end portion of the first rail portion (14c) in the radial direction is provided more outside in the radial direction than an outer end portion of the second rail portion (14a) in the radial direction is.

4. The starter according to any one of claims 1 through 3, wherein the locking portion (14b) is provided more outside in the radial direction than the second rail portion (14a) is.

5. The starter according to any one of claims 1 through 4,
wherein the locking portion (14b) is formed integrally with the base member (14), and
wherein when the brush holder (131, 132, 133, 134) is mounted at a predetermined position in the brush-holder mounting portion (141, 142, 143, 144), the locking portion (14b) engages with the brush holder (131, 132, 133, 134) by being bent in a direction departing from a flat portion (1411) of the base member (14).

6. The starter according to any one of claims 1 through 5,
wherein the brush holder (131, 132, 133, 134) has an endface portion (131m2) facing the outside in the radial direction,
wherein the locking portion (14b) has a side-surface portion (14b2) that abuts on the endface portion (131m2) of the brush holder (131, 132, 133, 134) from the outside in the radial direction, and
wherein at least one of the endface portion (13m2) of the brush holder (131, 132, 133, 134) and the side-surface portion (14b2) of the locking portion (14b2) is formed in such a way as to slant in a direction departing from the outer circumferential surface of the commutator (9) toward the downstream side in the rotation direction of the commutator (9).

7. The starter according to any one of claims 1 through 5,
wherein the brush holder (131, 132, 133, 134) has an endface portion (131m2) facing the outside in the radial direction,
wherein the locking portion (14b) has a side-surface portion (14b2) that abuts on the endface portion of the brush holder (131, 132, 133, 134) from the outside in the radial direction, and
wherein at least one of the endface portion (131m2) of the brush holder (131, 132, 133, 134) and the side-surface portion (14b2) of the locking portion (14b) is formed in such a way as to slant toward the outside in the radial direction, as the distance from the flat portion (1411) of the base member (14) perpendicular to the axial direction of the commutator (9) increases.
, Description:
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[See section 10, Rule 13]

STARTER

MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
SPECIFICATION

BACKGROUND OF THE INVENTION
Field of the Invention
[0001]
The present disclosure relates to a starter.

Description of the Related Art
[0002]
As is well known, a starter for starting an internal combustion engine has a motor unit that is configured in such a way as to obtain a commutation action through a brush that makes slidable contact with the outer circumferential portion of a commutator provided on an axis-direction end portion of a rotor shaft. The brush of the motor unit is slidably contained in a brush holder and is configured in such a way as to make slidable contact with the outer circumferential portion of the commutator, while being pressed thereto by a spring contained in the brush holder. Two or more brush holders are provided; each of these brush holders is fixed to a base member.
[0003]
In the brush and the brush holder of the motor unit in the starter configured in such a manner, due to frictional force between the commutator and the brush, a pressing load on the brush by the spring, and the like, the brush vibrates in a gap between the brush and the brush holder and the spring vibrates in a gap between the spring and the brush holder; each of those vibrations becomes not only a cause of occurrence of noise at a time when the starter operates but also a cause of shortening of the lifetime of the brush.
[0004]
To date, there have been proposed various kinds of technologies for suppressing vibration of a brush inside a brush holder; for example, Patent Document 1 proposes a technology in which an end-portion slant surface is formed at the anti-commutator-side of a brush and is pressed by a spring so that the brush is pressed not only toward the commutator but also toward the side wall of a brush holder and hence vibration of the brush is reduced. In addition, Patent Document 2 proposes a technology in which an urging means including a spring is provided with a seat surface for changing urging force of the spring in such a way that force of a brush pressing a commutator becomes smaller at the downstream side in the rotation direction of the commutator than at the upstream side in the rotation direction thereof.
[0005]
Meanwhile, as a configuration for fixing a brush holder to a base member of a motor unit so as to prevent the brush holder from vibrating, there has been utilized to date a configuration in which a brush holder is fixed by use of a screw, a vis, or the like or a configuration in which a brush holder, as a sheet metal component, is directly crimped and fixed to a base member.
[Prior Art Reference]
[Patent Literature]
[0006]
[Patent Document 1] Japanese Patent Application Laid-Open No. H5-211748
[Patent Document 2] Japanese Patent Application Laid-Open No. 2012-44842

SUMMARY OF THE INVENTION
[0007]
As described above, in a conventional starter for starting an internal combustion engine, various kinds of countermeasures have been taken to prevent vibrations of a brush and a spring 44 in a motor unit. In contrast, although as described above, a brush holder itself is fixed to a base member by use of a screw, a vis, or the like or the brush holder is directly crimped and fixed to the base member, no configuration for preventing vibration of the brush holder itself has been provided in a conventional starter.
[0008]
The present disclosure has been implemented in order to solve the foregoing problem; the objective thereof is to provide a starter provided with a brush holding apparatus that realizes prevention of vibration of a brush holder itself.
[0009]
A starter disclosed in the present disclosure includes
a yoke that forms a magnetic circuit,
an armature that is fixed on a rotor shaft and generates rotation torque based on magnetic flux from the yoke,
a commutator that is provided on the rotor shaft and that changes a direction of an electric current supplied from a power source and then supplies the electric current to the armature,
a brush that makes slidable contact with an outer circumferential surface of the commutator,
a spring that has elastic force for pressing the brush to the outer circumferential surface of the commutator,
a brush holder that contains the brush and the spring, and
a base member having a brush-holder mounting portion in which the brush holder is mounted; the starter is configured in such a way as to start an internal combustion engine through torque generated in the armature. The starter is characterized
in that the brush-holder mounting portion has
a first rail portion that extends in a radial direction of the commutator and slidably engages with the brush holder in the radial direction,
a second rail portion that extends in the radial direction of the commutator, that is disposed at an upstream side of the first rail portion in a rotation direction of the commutator, and that slidably engages with the brush holder in the radial direction, and
a locking portion that engages with the brush holder so as to prevent the brush holder from traveling toward the outside in the radial direction, when the brush holder engages with the first rail portion and the second rail portion so as to be mounted at a predetermined position in the brush-holder mounting portion, and
in that the brush holder mounted in the brush-holder mounting portion abuts on the locking portion by being pressed toward the outside in the radial direction, based on elastic force of the spring.
[0010]
The present disclosure makes it possible to obtain a starter provided with a brush holding apparatus that realizes prevention of vibration of a brush holder itself.
The foregoing and other object, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS
[0011]
FIG. 1 is a partial cross-sectional view illustrating a starter according to Embodiment 1;
FIG. 2 is a perspective view illustrating a brush holding apparatus of the starter according to Embodiment 1;
FIG. 3 is an explanatory view of a base member in the brush holding apparatus of the starter according to Embodiment 1;
FIG. 4 is an explanatory view of the brush holder when viewed in the direction of an arrow A in FIG. 2;
FIG. 5 is an explanatory view of the brush holder when viewed in the direction of an arrow B in FIG. 4;
FIG. 6 is a plan view of a base member in a brush holding apparatus of a starter according to Embodiment 2;
FIG. 7 is an explanatory view for explaining the function of the brush holding apparatus in the starter according to Embodiment 2;
FIG. 8 is a perspective view of a base member in a brush holding apparatus of a starter according to Embodiment 3; and
FIG. 9 is a cross-sectional view of the brush holding apparatus of the starter according to Embodiment 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012]
Embodiment 1.
FIG. 1 is a partial cross-sectional view illustrating a starter according to Embodiment 1. In FIG. 1, a starter 100 includes a solenoid switch 1 and a motor unit 2 as a DC motor. The motor unit 2 has a cylindrical tubular yoke 4 forming a magnetic circuit, a rear bracket 6 fitted with an opening portion at one axial-direction end of the yoke 4, and a front bracket 17 fitted with an opening portion at the other axial-direction end of the yoke 4.
[0013]
With a through-bolt 16, the front bracket 6 and the rear bracket 17 are tightened with each other, via the yoke 4, in a direction in which the front bracket 6 and the rear bracket 17 approach each other, so that the rear bracket 6 and the front bracket 17 are fixed integrally with the yoke 4. In the front bracket 17, there is mounted a transfer mechanism unit (unillustrated) that transfers torque, generated in a rotor shaft 8 of the motor unit 2, to an internal combustion engine (unillustrated). The axis-direction end portion, at the anti-yoke side, of the rear bracket 6 is sealed with an end wall portion 61. A screw 11 fixes the solenoid switch 1 to a protruding wall portion 171 formed integrally with the front bracket 17 of the motor unit 2.
[0014]
The motor unit 2 is provided with a stator 40 and a rotor 50. The stator 40 has the yoke 4 and two or more magnets 5, as magnetic-field magnetic poles, that are circularly arranged on the inner circumferential surface of the yoke 4. The rotor 50 is provided with an armature 7 having an armature coil 3 fixed to the rotor shaft 8 and a commutator 9 fixed to the rotor shaft 8. The commutator 9 is disposed at an axis-direction end portion of the rotor shaft 8 and is contained in the rear bracket 6. The commutator 9 is formed in the shape of a cylindrical tube in such a way that as is well known, two or more commutator segments and two or more insulating segments are alternately arranged. The two or more commutator segments are connected with two or more respective coil terminals of the armature coil 3.
[0015]
A bearing 15 for pivotably supporting the rotor shaft 8 is provided on the inner surface of the end wall portion 61 of the rear bracket 6. In addition, a brush holding apparatus 70 is fixed to the inner surface of the end wall portion 61 of the rear bracket 6. The brush holding apparatus 70 includes a discoidal metal base member 14 having a central through-hole 140 in the center portion thereof, and a first brush holder 131, a second brush holder 132, a third brush holder 133, and a fourth brush holder 134 that are each mounted on the base member 14 (in FIG. 1, only the first brush holder 131 is illustrated).
[0016]
In the base member 14, the bearing 15 penetrates the central through-hole 140 thereof, and a first flat portion 1411 (refer to after-mentioned FIG. 2) and a second flat portion 1412 (refer to after-mentioned FIG. 2), which are in a front-and-back relationship, are arranged in such a way as to be perpendicular to the axial direction of the rotor shaft 8. The foregoing first brush holder 131, second brush holder 132, third brush holder 133, and fourth brush holder 134 are mounted on the first flat portion 1411 of the base member 14; the second flat portion 1412 of the base member 14 abut on and is fixed to the inner surface of the end wall portion 61 of the rear bracket 6.
[0017]
Next, the brush holding apparatus 70 of the starter according to Embodiment 1 will be explained. FIG. 2 is a perspective view illustrating the brush holding apparatus of the starter according to Embodiment 1; FIG. 3 is an explanatory view of the base member in the brush holding apparatus of the starter according to Embodiment 1; FIG. 4 is an explanatory view of the brush holder when viewed in the direction of an arrow A in FIG. 2; FIG. 5 is an explanatory view of the brush holder when viewed in the direction of an arrow B in FIG. 4. As illustrated in FIGS. 2 and 3, the first brush holder 131, the second brush holder 132, the third brush holder 133, and the fourth brush holder 134 are mounted, in such a manner as described later, on the first flat portion 1411 of the base member 14 having the central through-hole 140.
[0018]
In FIGS. 2, 4, and 5, the first brush holder 131 has
a top-surface portion 131a that extends horizontally,
upper flat portions 131b1 and 131b2 that each vertically bend and extend from the top-surface portion 131a toward the base member 14,
swelling portions 131c1 and 131c2 that each swell in an arc-shaped manner from the upper flat portions 131b1 and 131b2, respectively, toward the respective sides thereof,
lower flat portions 131d1 and 131d2 that each vertically bend from the swelling portions 131c1 and 131c2, respectively, and extend toward the base member 14,
a bottom-surface portion 131e that vertically bend from the lower flat portions 131d1 and 131d2 and extend in parallel with the flat portion of the base member 14, and
a base portion 131f that is formed in such a way as to protrude from the bottom-surface portion 131e toward the base member 14.
[0019]
A first U-shaped groove 131g1 and a second U-shaped groove 131g2 are provided in the respective boundary portions between the both corresponding side-surface portions of the base portion 131f and the lower flat portions 131d1 and 131d2. In the swelling portions 131c1 and 131c2, there are provided cutout portions 131h1 and 131h2 that extend from opening end edges 131c11 and 131c21, respectively, thereof toward an end wall portion 131k.
[0020]
The base portion 131f is formed in such a way that the length between one endface portion 131m1 and the other endface portion 131m2 thereof is shorter than each of the length between the swelling portions 131c1 and 131c2, the length between the upper flat portions 131b1 and 131b2, and the length between the lower flat portions 131d1 and 131d2. The endface portion 131m2 of the base portion 131f is formed in such a way as to extend in a direction perpendicular to the flat portion of the base member 14 from the bottom-surface portion 131e of the first brush holder 131 and in such a way as to face the radial-direction outside of the base member 14.
[0021]
As indicated by a broken line in each of FIGS. 4 and 5, a strip-shaped brush 10 is contained in the inner space of the first brush holder 131 in such a way as to be slidable in the radial direction of the base member 14. In addition, as indicated by a broken line in each of FIGS. 4 and 5, a spring 12, which is a coil-shaped compression spring, is contained in the inner space of the first brush holder 131. One end portion of the spring 12 abuts on the inner wall surface of the end wall portion 131k of the first brush holder 131; the other end portion of the spring 12 abuts on one end portion of the brush 10. The brush 10 is constantly pressed by elastic force of the spring 12 toward the center “O” of the base member 14, i.e., in a direction perpendicular to the outer circumferential surface of the commutator 9 and slidably abuts on the outer circumferential surface of the commutator 9. The commutator 9 rotates in the direction of an arrow X in FIG. 3, with respect to the base member 14.
[0022]
Each of the second brush holder 132, the third brush holder 133, and the fourth brush holder 134 is configured in the same manner as the foregoing first brush holder 131 and contains the brush 10 and the spring 12.
[0023]
Next, the base member 14 will be explained. As illustrated in FIG. 2, in the base member 14, there are provided a first brush-holder mounting portion 141, a second brush-holder mounting portion 142, a third brush-holder mounting portion 143, and a fourth brush-holder mounting portion 144 around the central through-hole 140.
[0024]
In FIGS. 2 and 3, the first brush-holder mounting portion 141 has
a first rail portion 14c that extends in the radial direction of the base member 14, i.e., in the radial direction of the commutator 9,
a second rail portion 14a that is provided in such a way as to be spaced apart from and stand face to face with the first rail portion 14c in the circumferential direction of the base member 14 and that extends in the radial direction of the base member 14, and
a locking portion 14b that is disposed at the outside of the second rail portion 14a in the radial direction of the base member 14.
[0025]
The second rail portion 14a in the first brush-holder mounting portion 141 is situated at the downstream side of the first rail portion 14c in a rotation direction X of the commutator 9. The inner end portion of the first rail portion 14c in the radial direction of the commutator 9 is provided more inside in the radial direction of the commutator 9 than the inner end portion of the second rail portion 14a in the radial direction of the commutator 9 is. In addition, the outer end portion of the first rail portion 14c in the radial direction of the commutator 9 is provided more outside in the radial direction of the commutator 9 than the outer end portion of the second rail portion 14a in the radial direction of the commutator 9 is.
[0026]
The locking portion 14b has a pair of side-surface portions 14b1 and 14b2 that face each other in the radial direction of the commutator 9; these side-surface portions 14b1 and 14b2 are formed in such a way as to extend in parallel with each other and to each extend in a direction perpendicular to the radial direction of the base member 14, i.e., to the radial direction of the commutator 9.
[0027]
The first brush-holder mounting portion 141 is formed in such a way that for example, a pressing machine punches a punching hole 14d in the base member 14, leaving the first rail portion 14c, the second rail portion 14a, and the locking portion 14b. When the punching is performed by a pressing machine, the first rail portion 14c, the second rail portion 14a, and the locking portion 14b are formed in a planar manner on a plate that is one and the same as the base member 14; after the punching, as illustrated in FIG. 2, the first rail portion 14c and the second rail portion 14a are raised from the first flat portion 1411 of the base member 14, so that as described later, the first rail portion 14c and the second rail portion 14a can slidably engage with and hold the first brush holder 131.
[0028]
Moreover, as described later, by engaging with the first brush holder 131 mounted in the first brush-holder mounting portion 141, the locking portion 14b prevents the first brush holder 131 from falling down from the first brush-holder mounting portion 141 toward the radially outside of the commutator 9.
[0029]
Each of the second brush-holder mounting portion 142, the third brush-holder mounting portion 143, and the fourth brush-holder mounting portion 144 is configured in the same manner as the foregoing first brush holder mounting portion 141.
[0030]
As illustrated in FIG. 2, the first brush-holder mounting portion 141 and the third brush-holder mounting portion 143 are arranged in such a way as to face each other via the center “O” of the base member 14; the second brush-holder mounting portion 142 and the fourth brush-holder mounting portion 144 are arranged in such a way as to face each other via the center “O” of the base member 14.
[0031]
The brush 10 held by the first brush holder 131 and the brush 10 held by the third brush holder 133 are connected with the positive-polarity side of a power source. The brush 10 held by the second brush holder 132 and the brush 10 held by the fourth brush holder 134 are connected with the negative-polarity side of the power source. A lead wire (unillustrated) is embedded in each of the respective brushes 10 inserted in the first brush holder 131, the second brush holder 132, the third brush holder 133, and the fourth brush holder 134.
[0032]
The respective lead wires of the brushes 10, which are inserted into the first brush holder 131 and the third brush holder 133 and are connected with the positive-polarity side of the power source, are pulled out to the outside of the motor unit 2 through a grommet 21 attached to a through-hole (unillustrated) formed in the yoke 4 illustrated in FIG. 4 and then are connected with the power source via switches or the like. The respective lead wires of the brushes 10, which are inserted into the second brush holder 132 and the fourth brush holder 134 and are connected with the negative-polarity side of the power source, are connected with the first flat portion 1411 of the base member 14, for example, through welding. The base member 14 is provided with a raised portion 1402 to which the foregoing grommet 21 is fixed. A through-hole 1401 is formed in the base member 14 through punching for the foregoing raised portion 1402.
[0033]
As illustrated in FIG. 3, in the radial direction of the commutator 9, an inner punching position 14a1, in the base member 14, of the second rail portion 14a of the first brush-holder mounting portion 141 is situated at the outside of the inner punching position 14c1 of the first rail portion 14c. Each of the second brush-holder mounting portion 142, the third brush-holder mounting portion 143, and the fourth brush-holder mounting portion 144 is configured in the same manner as the first brush holder mounting portion 141.
[0034]
When as described above, in the radial direction of the commutator 9, the inner punching position 14a1 of the second rail portion 14a is situated at the outside of the inner punching position 14c1 of the first rail portion 14c, it is made possible that in comparison with the case where the foregoing configuration is not implemented, a distance “a” between the punching position 14a1 of the second rail portion 14a in the first brush-holder mounting portion 141 and the punching position 14c1 of the first rail portion 14c in the second brush-holder mounting portion 142 is made large without shortening the length of the first rail portion 14c.
[0035]
As a result, when the first brush-holder mounting portion 141 though the fourth brush-holder mounting portion 144 are formed by punching the base member 14, the distance “a” between the adjacent first and second brush-holder mounting portions 141 and 142 and the distance “a” between the adjacent third and fourth brush-holder mounting portions 143 and 144 can be made large; therefore, the workability of the base member 14 is raised. Furthermore, because the rigidity of the base member 14 can be raised by increasing the distance “a” between the adjacent brush-holder mounting portions, the base member 14 is prevented from being deformed by a tightening load of the through-bolt 16 at a time when the motor unit 2 is assembled; thus, the respective mounting positions of the first brush holder 131 through the fourth brush holder 134 can more accurately be set.
[0036]
In addition, the length, in the radial direction of the commutator 9, of the second rail portion 14a that is situated at the upstream side of the first rail portion 14c in the rotation direction X of the commutator 9 is made shorter than that of the first rail portion 14c, so that the locking portion 14b can be provided at the radially outside of the second rail portion 14a.
[0037]
As illustrated in FIG. 2, the first brush holder 131 is mounted in the first brush-holder mounting portion 141 formed in the base member 14; the second brush holder 132 is mounted in the second brush-holder mounting portion 142; the third brush holder 133 is mounted in the third brush-holder mounting portion 143; the fourth brush holder 134 is mounted in the fourth brush-holder mounting portion 144.
[0038]
Next, there will be explained the method of mounting the brush holder in the base member 14. In the following explanation, the method of mounting the first brush holder 131 in the first brush-holder mounting portion 141 will be explained; however, the second brush holder 132, the third brush holder 133, and the fourth brush holder 134 are mounted in the second brush-holder mounting portion 142, the third brush-holder mounting portion 143, and the fourth brush-holder mounting portion 144, respectively, in the same manner as the first brush holder 131 is mounted.
[0039]
Before the first brush holder 131 through the fourth brush holder 134 are mounted on the base member 14, the first rail portion 14c and the second rail portion 14a in each of the first brush-holder mounting portion 141 though the fourth brush-holder mounting portion 144 of the base member 14 are raised from the first flat portion 1411 of the base member 14, as illustrated in FIG. 2. At this time, the locking portion 14b has not been raised and is left in a planar manner.
[0040]
The base member 14 formed in such a manner as described above is held in a state where the rotor shaft 8 provided with the commutator 9 penetrates the central through-hole 140 thereof; next, the first rail portion 14c of the first brush-holder mounting portion 141 is inserted into the first U-shaped groove 131g1 of the first brush holder 131 from the radial-direction outside of the base member 14. At this moment, as indicated by the broken lines in each of FIGS. 4 and 5, the brush 10 and the spring 12 have preliminarily been contained in the first brush holder 131. Accordingly, when the first brush holder 131 is mounted in the first brush-holder mounting portion 141, the elastic force of the spring 12 makes the endface, at the opposite side of the spring 12, of the brush 10 abut on the surface of the commutator 9.
[0041]
Next, in the above situation, the first brush holder 131 is made to slide toward the radial-direction inside of the base member 14 while resisting the elastic force of the spring 12, so that the second rail portion 14a of the first brush-holder mounting portion 141 is inserted into the second U-shaped groove 131g2 of the first brush holder 131. Next, in that situation, the first brush holder 131 is made to slide toward the radial-direction inside of the base member 14 up to the position thereof illustrated in FIG. 2, while the spring 12 is being compressed.
[0042]
After the first brush holder 131 is made to reach the position indicated in FIG. 2 in such a manner as described above, the locking portion 14b in the first brush-holder mounting portion 141 of the base member 14 is raised from the first flat portion 1411 of the base member 14; then, the radially-inside side-surface portion 14b2 of the locking portion 14b is made to abut on the endface portion 131m2 (refer to FIG. 4) in the base portion 131f of the first brush holder 131. As a result, the first brush holder 131 is pressed to the locking portion 14b by the elastic force of the spring 12.
[0043]
Because mounted in the first brush-holder mounting portion 141 in such a manner as described above, the first brush holder 131 is prevented from falling down from the first brush-holder mounting portion 141 toward the radially outside of the commutator 9; concurrently, because constantly pressed to the locking portion 14b by the elastic force of the spring 12, vibration of the first brush holder 131 itself is suppressed.
[0044]
The brush 10 is constantly pressed by the spring 12 toward the radially inside of the commutator 9; as illustrated in FIG. 1, the anti-spring-side end portion of the brush 10 is pressed to the outer circumferential portion of the commutator 9, which penetrates the through-hole in the base member 14, and make slidable contact with the outer circumferential surface of the rotating commutator 9.
[0045]
The structure, in which as described above, the first brush holder 131 through the fourth brush holder 134 are inserted into the first brush-holder mounting portion 141 though the fourth brush-holder mounting portion 144, respectively, from the outer-circumferential side of the base member 14, i.e., from the radial-direction outside, makes it possible to assemble the two or more brush holders, for example, concurrently, with the base member 14; thus, the assembly man-hours can be reduced.
[0046]
As illustrated in FIG. 1, the brush holder 70 configured as described above is fixed to the inside of the rear bracket 6. The brush 10 attached to the brush holding apparatus 70 makes slidable contact with the circumferential surface of the commutator 9. In this situation, the first brush holder 131 through the fourth brush holder 134 are pressed by the respective springs 12 contained therein toward the side opposite to the commutator 9 side, i.e., toward the radial-direction outside of the base member 14, and hence are pressed to and abut on the respective locking portions 14b of the first brush-holder mounting portion 141 through the fourth brush-holder mounting portion 144, as described above.
[0047]
As described above, because the first brush holder 131 through the fourth brush holder 134 are pressed by the respective springs 12 contained therein toward the side opposite to the commutator 9 side so as to abut on the respective locking portions 14b, vibration thereof are suppressed in comparison with conventional brush holders.
[0048]
In the starter 100, illustrated in FIG. 1, according to Embodiment 1, when the solenoid switch 1 is turned on, a vehicle battery (unillustrated) as the power source supplies an electric current to the armature coil 3 via the brush 10 and the commutator 9. The current flowing in the armature coil 3 is interlinked with magnetic flux from the magnet 5 provided in the yoke 4, so that torque is generated in the rotor 50 having the armature coil 3 and hence the rotor 50 rotates. When the rotor 50 rotates, the commutator 9 integrally fixed on the rotor 50 and the brush 10 sliding on the outer circumferential surface of the commutator 9 perform commutation, as is well known; the rotor 50 continuously rotates. As a result, the internal combustion engine is started through the transfer mechanism unit (unillustrated) coupled with the rotor shaft 8 of the motor unit 2.
[0049]
Embodiment 2.
Next, a brush holding apparatus of a starter according to Embodiment 2 will be explained. The starter according to Embodiment 2 is the same as the starter in FIG. 1, except for the configuration of a brush holding apparatus 70. FIG. 6 is a plan view of a base member in the brush holding apparatus of the starter according to Embodiment 2.
[0050]
In FIG. 6, the locking portion 14b of the first brush-holder mounting portion 141 provided in the base member 14 is formed in such a way that the side-surface portion 14b2 thereof at the inside in the radial direction of the base member 14, i.e., in the radial direction of the commutator 9, that is to say, the side-surface portion 14b2 abutting on the endface portion 131m2 (refer to FIG. 4) of the base portion 131f of the first brush holder 131 is slanted from the endface portion 131m2 of the base portion 131f of the first brush holder 131.
[0051]
In other words, the locking portion 14b has the side-surface portion 14b2 that abuts on the endface portion 131m2 in the base portion 131f of the first brush holder 131 from the outside in the radial direction of the commutator 9; the endface portion 131m2 of the base portion 131f of the first brush holder 131 and the side-surface portion 14b2 of the locking portion 14b are formed in such a way as to depart from the outer circumferential surface of the commutator 9 toward the downstream side in the rotation direction of the commutator 9.
[0052]
The other configurations are the same as those of the brush holding apparatus according to Embodiment 1. In addition, although not illustrated, each of the second brush holder, the third brush holder, and the fourth brush holder is configured in the same manner as the foregoing first brush holder, and each of the second brush-holder mounting portion, the third brush-holder mounting portion, and the fourth brush-holder mounting portion is configured in the same manner as the foregoing first brush-holder mounting portion 141.
[0053]
FIG. 7 is an explanatory view for explaining the function of the brush holding apparatus in the starter according to Embodiment 2. In FIG. 7, pressing force e0 based on the elastic force of the spring 12 contained in the first brush holder 131 presses the first brush holder 131 to the side-surface portion 14b2 of the locking portion 14b of the first brush-holder mounting portion 141. In this situation, because as described above, the side-surface portion 14b2 of the locking portion 14b is formed in such a way as to be slanted from the endface portion 131m2 of the base portion 131f of the first brush holder 131, only an end edge of the endface portion 131m2 in the base portion 131f of the first brush holder 131 abuts on the side-surface portion 14b2 of the locking portion 14b.
[0054]
The pressing force e0 to be exerted on the side-surface portion 14b2 of the locking portion 14b is decomposed into component force e1 perpendicular to the side-surface portion 14b2 of the locking portion 14b and component force e2 perpendicular to the component force e1. The component force e2 pushes the first brush holder 131 to the first rail portion 14c of the first brush-holder mounting portion 141. Because the commutator 9 rotates in the direction indicated by an arrow X in FIG. 7, the brush 10 receives frictional force b in the rotation direction X of the commutator 9, due to contact with the outer circumferential surface of the commutator 9. Accordingly, force c that is one and the same as the frictional force b pushes the first brush holder 131 to the first rail portion 14c of the first brush-holder mounting portion 141 through the brush 10.
[0055]
As a result, because the component force e2 of the pressing force e0 exerted by the spring 12 and the force c based on the frictional force b caused by rotation of the commutator 9 constantly pushes the first brush holder 131 to the first rail portion 14c, vibration of the first brush holder 131 itself is suppressed.
[0056]
In the above explanation, only the operation between the first brush holder 131 and the first brush-holder mounting portion 141 has been described; however, each of the operation between the second brush holder and the second brush-holder mounting portion, the operation between the third brush holder and the third brush-holder mounting portion, and the operation between the fourth brush holder and the fourth brush-holder mounting portion is the same as the operation between the first brush holder 131 and the first brush-holder mounting portion 141.
[0057]
In addition, in the foregoing explanation, the side-surface portion 14b2 of the locking portion 14b has been slanted; however, it may be allowed that the endface portion 131m2 of the base portion 131f of the brush holder is slanted.
[0058]
Embodiment 3.
Next, a brush holding apparatus according to Embodiment 3 will be explained. A starter according to Embodiment 3 is the same as the starter in FIG. 1, except for the configuration of a brush holding apparatus 70. FIG. 8 is a perspective view of a base member in the brush holding apparatus of the starter according to Embodiment 3.
[0059]
In FIG. 8, the locking portion 14b of the first brush-holder mounting portion 141 provided in the base member 14 has the side-surface portion 14b2 that abuts on the endface portion 131m2 in the base portion 131f of the first brush holder 131 from the outside in the radial direction of the commutator 9; the endface portion 131m2 of the base portion 131f of the first brush holder 131 and the side-surface portion 14b2 of the locking portion 14b are formed in such a way as to become more slanted toward the outside in the radial direction of the commutator 9, as the distance from the flat portion of the base member 14 perpendicular to the axial direction of the commutator 9 increases.
[0060]
The other configurations of the first brush-holder mounting portion 141 are the same as those of the brush-holder mounting portion in the brush holding apparatus according to Embodiment 1. Although not illustrated, each of the second brush-holder mounting portion, the third brush-holder mounting portion, and the fourth brush-holder mounting portion is configured in the same manner as the first brush-holder mounting portion 141.
[0061]
FIG. 9 is a cross-sectional view of the brush holding apparatus of the starter according to Embodiment 3. In FIG. 9, the first brush holder 131 is formed in such a way that the endface portion 131m2 of the base portion 131f becomes more slanted toward the outside in the radial direction of the commutator 9, as the distance from the flat portion of the base member 14 perpendicular to the axial direction of the commutator 9 increases. When the elastic force of the spring 12 (unillustrated) contained in the first brush holder 131 presses the first brush holder 131 to the side-surface portion 14b2 of the locking portion 14b of the first brush-holder mounting portion 141, the slanted side-surface portion 14b2 of the locking portion 14b and the slanted endface portion 131m2 of the base portion 131f of the first brush holder 131 make facial contact with each other, so that the first brush holder 131 is pushed up to the side opposite to the base member 14, along the slanted side-surface portion 14b2 of the locking portion 14b.
[0062]
As a result, the inner-surface portion, at the base member 14 side, of the first U-shaped groove 131g1 (unillustrated) provided in the base portion 131f of the first brush holder 131 is pressed to the plane portion, at the base member 14 side, of the first rail portion 14c (unillustrated); similarly, the inner-surface portion, at the base member 14 side, of the second U-shaped groove 131g2 provided in the base portion 131f of the first brush holder 131 is pressed to the plane portion, at the base member 14 side, of the second rail portion 14a. In addition, the side-surface portion 14b2 of the locking portion 14b of the first brush-holder mounting portion 141 presses the endface portion 131m2 of the base portion 131f of the first brush holder 131.
[0063]
As a result, based on pressing force from the spring 12, the slanted side-surface portion 14b2 of the locking portion 14b presses up the first brush holder 131 in a direction perpendicular to the flat portion of the base member 14; the first brush holder 131 is pressed by and fixed to the plane portion, at the base member 14 side, of the first rail portion 14c and the plane portion, at the base member 14 side, of the second rail portion 14a, so that vibration of the first brush holder 131 itself is suppressed. Moreover, because the first brush holder 131 does not slant toward the rotor shaft 8, uneven wear of the brush 10 is suppressed and hence an effect for prolongation of the lifetime is demonstrated.
[0064]
In the above explanation, only the operation between the first brush holder 131 and the first brush-holder mounting portion 141 has been described; however, each of the operation between the second brush holder and the second brush-holder mounting portion, the operation between the third brush holder and the third brush-holder mounting portion, and the operation between the fourth brush holder and the fourth brush-holder mounting portion is the same as the operation between the first brush holder 131 and the first brush-holder mounting portion 141.
[0065]
In addition, with regard to each of the starters according to the foregoing embodiments 1 through 3, there has been explained the case where the starter has four brush holders and four brush-holder mounting portions; however, neither the number of the brush holders nor the number of the brush-holder mounting portions is limited to four.
[0066]
In the starter according to each of the foregoing embodiments, because the respective rail portions of the adjacent brush-holder mounting portions in the base member do not become so close to each other that the strength of the base member is deteriorated, the rail portions can be situated at a side, in the base member, that is closer to the commutator; thus, because when frictional force caused by rotation of the commutator pulls the brush toward the downstream side in the rotation direction of the commutator, wobble of the brush holder is reduced and hence is suppressed from vibrating, so that it is made possible to expect prevention of noise and prolongation of the lifetime of the brush.
[0067]
Moreover, in the starter according to each of the foregoing embodiments, the rail portion at the downstream side in the rotation direction of the commutator is made long, so that the contact surface between the base member and the brush holder increases and hence the vibration-suppression effect can be raised.
[0068]
Furthermore, in the starter according to each of the foregoing embodiments, the simple structure, in which it is only required that the brush holder is inserted into the brush-holder mounting portion so that the locking portion of the base member is raised, does not increase the number of components, and the assembly time can be shortened by concurrently inserting two or more brush holders into the base member. In addition, the brush holder is pressed to and fixed to the base member, so that vibration of the brush holder can be suppressed. Suppression of vibration makes it possible to reduce noise and to prolong the lifetime of the brush.
[0069]
In addition, the brush holder is pressed to and fixed to the surface, at the base member side, of the rail portion, so that the brush holder can be prevented from slanting toward the rotor shaft; thus, it is made possible to prevent the brush from being unevenly worn and to prolong the lifetime thereof.
[0070]
Although the present application is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functions described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations to one or more of the embodiments. Therefore, an infinite number of unexemplified variant examples are conceivable within the range of the technology disclosed in the present application. For example, there are included the case where at least one constituent element is modified, added, or omitted and the case where at least one constituent element is extracted and then combined with constituent elements of other embodiments.