Starter

Details Starter Starter

2000-03-24

2001-04-24

Nguyen, Tran (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S091000, C290S03800C, C290S03800C, C074S00700R, C074S00700R, C074S00700R

Reexamination Certificate

active

06222293

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a starter having an epicyclic gear reduction unit for reducing the rotation of a motor output shaft integrated with an armature and transmitting the reduced rotation to a starting output shaft and, particularly, to an impact absorbing unit for a starter which absorbs impact stress caused by excessive rotation torque on a load side.
2. Description of the Prior Art
FIG. 14
is a partly exploded side view of a starter incorporating an epicyclic gear reduction unit of the prior art and
FIG. 15
is a front view showing key parts of the mated internal gear of the epicyclic gear reduction unit in the starter of the prior art.
In FIG.
14
and
FIG. 15
, the starter comprises a starting motor
3
for generating rotation force, an epicyclic gear reduction unit for reducing the rotation of the motor output shaft
4
of this starting motor
3
and outputting the reduced rotation, an overrunning clutch
7
which is fitted onto the starting output shaft
6
of the epicyclic gear reduction unit
5
, a pinion
8
which can slide over the starting output shaft
6
together with this overrunning clutch
7
, and an electromagnetic switch
9
for controlling power supply to the starting motor
3
and urging the pinion
8
toward the ring gear
14
of an engine together with the overrunning clutch
7
through a shift lever
10
.
This starting motor
3
is formed like a bottomed cylinder and comprises a yoke
11
which also functions as an outer frame and magnetic circuit, a field coil
12
placed on the yoke
11
, an armature
13
placed on the inner side of the field coil
12
, a rectifier (not shown) attached to the motor output shaft
4
which is the rotation shaft of the armature
13
, and a brush (not shown) in sliding contact with the rectifier. A rear bracket
2
is mated with the rear end of the yoke
11
to be connected to the yoke
11
so as to supports the rear end of the motor rotation shaft
4
. A front bracket
1
is mated with the front end of the yoke
11
to be connected to the yoke
11
.
This epicyclic gear reduction unit
5
comprises a sun gear
15
formed around the front end of the motor rotation shaft
4
, a plurality of epicyclic gears
16
which mesh with the sun gear
15
and an internal gear
17
which meshes with the epicyclic gears
16
.
As shown in
FIG. 15
, the internal gear
17
is formed like a bottomed cylinder having a center hole in the center of the bottom portion, rotation stoppers
19
formed on the outer wall and an internal gear portion
18
formed on the inner wall. The internal gear
17
is fixed to the front bracket
1
so that it is open at the rear end (on the armature side). The rotation stoppers
19
are mated with the front bracket
1
to limit the movement in a circumferential direction of the internal gear
17
. The rotation stoppers
19
are required to transmit torque required by the engine from the motor rotation shaft
4
to the starting output shaft
6
.
A disk-like flange portion
20
is formed at the rear end of the starting output shaft
6
integratedly. A plurality of pins
21
are provided on the rear end surface of the flange portion
20
concentrically at an equal angular pitch. The epicyclic gears
16
are supported by the respective pins
21
rotably. This flange portion
20
, namely, the starting output shaft
6
is rotably supported by a bearing
22
fixed in the center hole of the internal gear
17
fixed to the front bracket
1
, and the front end portion of the motor output shaft
4
is rotably supported by a bearing
23
fixed to the flange portion
20
. Thereby, the plurality of epicyclic gears
16
mesh with the sun gear
15
and the internal gear portion
18
to constitute the epicyclic gear reduction unit
5
.
The sun gear
15
rotates together with the motor rotation shaft
4
to transmit the rotation of the motor rotation shaft
4
to each of the epicyclic gears
16
. The epicyclic gears
16
revolve round the sun gear
15
by the rotation of the sun gear
15
while they rotate on their own axes. The starting output shaft
6
is rotated by this revolution of the epicyclic gears
16
.
The overrunning clutch
7
can move in an axial direction and is fitted onto the starting output shaft
6
. The pinion
8
is connected to the front end portion of a sleeve shaft
24
constituting the overrunning clutch
7
. A shift lever
10
is installed such that it can rotate on an intermediate fulcrum portion
10
a
, one end of which is mated with the overrunning clutch
7
and the other end is connected to the plunger (not shown) of the electromagnetic switch
9
installed above the starting motor
3
.
A description is subsequently given of the operation of this starter of the prior art constituted as described above.
Before the operation of the starter, the shift lever
10
is first located at a position shown in
FIG. 14
, the overrunning clutch
7
does not move, and the pinion
8
is not mated with the ring gear
14
.
Then, when a key switch (not shown) is closed and the starter is activated, the armature
13
is energized with power supplied from the electromagnetic switch
9
and rotated by the energization force of the field coil
12
. The motor output shaft
4
integrated with the armature
13
is rotated by the rotation of the armature
13
. The shift lever
10
is driven by the plunger of the electromagnetic switch
9
and turned on the fulcrum portion
10
a
in the counterclockwise direction of FIG.
14
. The overrunning clutch
7
is pressed by the rotation of this shift lever
10
and moves the starting output shaft
6
forward (right direction in
FIG. 14
) together with the pinion
8
, and the pinion
8
is thereby mated with the ring gear
14
.
At this point, rotation torque output from the armature
13
is transmitted from the sun gear
15
of the motor output shaft
4
to the epicyclic gears
16
. The epicyclic gears
16
rotate on the respective pins
21
between the sun gear
15
and the internal gear portion
18
. That is, the epicyclic gears
16
revolve round the sun gear
15
while they rotate on their own axes. The flange portion
20
supporting the epicyclic gears
16
rotates at a speed lower than the rotation speed of the motor output shaft
4
by the revolution of the epicyclic gears
16
and transmits this reduced rotation output to the starting output shaft
6
. The starting output shaft
6
rotates the ring gear
14
(crank shaft) through the overrunning clutch
7
and the pinion
8
at a reduced speed.
In this type of starter, the crank shaft which is connected to the starting output shaft
6
to be rotated may stop suddenly, or the starting output shaft
6
being rotated may be connected to the crank shaft suddenly. In this case, excessive rotation torque is applied to the starting output shaft
6
all of a sudden. The rotation torque applied to the starting output shaft
6
is transmitted from the flange portion
20
at one end of the starting output shaft
6
to the epicyclic gears
16
, then to the internal gear
17
through the internal gear portion
18
and finally to the motor output shaft
4
through the sun gear
15
.
In the above starter of the prior art, as the internal gear
17
and the front bracket
1
are connected to each other by the rotation stoppers
19
, impact stress caused by excessive rotation torque on a load side which undergoes a sudden change may be transmitted to the front bracket
1
and the motor output shaft
4
through the epicyclic gear reduction unit
5
and break a fragile portion of each element of the output transmission system of the starter.
SUMMARY OF THE INVENTION
The starter of the present invention comprises a fixing member which has a cylindrical portion and rotation stoppers on the outer wall of the cylindrical portion and is fixed to a bracket so that its movement in a circumferential direction is limited by the rotation stoppers, a mating portion is formed by mating the inner surface of the cylindrical portion of the fixing member with the outer surface of the internal

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