Machine element or mechanism – Engine starters – Automatic
Reexamination Certificate
2001-08-24
2004-06-22
Fenstermacher, David (Department: 3682)
Machine element or mechanism
Engine starters
Automatic
C074S00700R, C403S348000
Reexamination Certificate
active
06752032
ABSTRACT:
REFERENCE TO RELATED APPLICATIONS
This application is based on Japanese Patent Application No. 2000-257439, filed in Japan on Aug. 28, 2000, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a starting apparatus for an internal combustion engine having a pinion moving mechanism which can reliably perform engagement and disengagement of a pinion of the starting apparatus with respect to a ring gear of an engine.
2. Description of the Related Art
An internal combustion engine for an automobile, for example, is typically started by engaging a pinion of a starting apparatus with a ring gear of the internal combustion engine and rotating the pinion with an electric starter motor. In order to smoothly carry out starting, it is necessary to perform meshing and disengagement of the pinion and the ring gear with certainty. An example of an arrangement for engaging a pinion of a starting apparatus with a ring gear of an engine is described in Japanese Published Unexamined Patent Application Sho 64-56966.
FIG. 6
is a longitudinal cross-sectional view of an example of a starting apparatus disclosed in that publication. In the starting apparatus of
FIG. 6
, a shaft
1
of an electric motor has a gear
2
mounted thereon for driving a one-way clutch. The one-way clutch includes an outer portion
3
, an inner portion
6
, and a plurality of rollers
5
which transmit torque between the outer portion
3
and the inner portion
6
. The outer portion
3
is equipped with a gear
4
on its outer periphery which engages with the gear
2
mounted on the shaft
1
. The inner portion
6
of the one-way clutch is rotatably supported by bearings
7
and
8
mounted in a housing
9
.
A pinion shaft
10
is disposed inside the one-way clutch and engages with the inner portion
6
of the clutch through a helical spine
11
. A pinion
12
is mounted on the pinion shaft
10
and engages it through a helical spline
13
. Helical spline
11
and helical spline
13
spiral in the opposite rotational direction from the direction in which the pinion shaft
10
is rotated by the electric motor (i.e., like a right-hand thread in the example shown in
FIG. 6
in which the motor rotates in counterclockwise direction as viewed from the tip of the output shaft), and helical spline
13
has a greater lead angle than helical spline
11
. The position of the pinion
12
on the pinion shaft
10
is restricted by a stopper
14
mounted on the pinion shaft
10
. A spring
15
for pressing the pinion
12
towards the stopper
14
is disposed between the pinion
12
and a washer
16
. A pinion return spring
17
disposed between the inner portion
6
of the clutch and the left end of the pinion shaft
10
urges the pinion shaft
10
and the pinion
12
to the left in the figure. The pinion shaft
10
and the pinion
12
can be shifted to the right in the figure by a shift lever
18
for bringing the pinion
12
into engagement with a ring gear
19
of an unillustrated internal combustion engine.
The starting apparatus of
FIG. 6
performs starting operation in the following manner. The shift lever
18
moves the pinion shaft
10
against the force of the pinion return spring
17
towards the ring gear
19
, the electric motor is driven to generate a torque limited to a prescribed value, and the pinion shaft
10
and the pinion
12
are driven through the outer portion
3
, the rollers
5
, and the inner portion
6
of the clutch. The pinion
12
is moved together with the pinion shaft
10
to the right in the figure, and it engages with the ring gear
19
. As the pinion shaft
10
and the pinion
12
move to the right, they rotate in accordance with the lead angle of helical spline
11
. If the teeth surfaces of the pinion
12
and the ring gear
19
collide without meshing with each other, the spring
15
is deformed by the movement of the pinion shaft
10
, so the pinion
12
rotates due to the difference between the lead angles of helical spline
11
and helical spline
13
and completes meshing with the ring gear
19
, and with the completion of meshing the electric motor is fully energized and the internal combustion engine is started.
FIGS. 7 and 8
are longitudinal cross-sectional views of another example of a starting apparatus for an internal combustion engine which has been proposed in the past. In this example, a gear
2
which is mounted on a shaft
1
of an electric motor meshes with a gear
21
which is mounted on an output shaft
20
. A helical external spline
22
is formed on the output shaft
20
. A one-way clutch
23
includes an outer or drive portion
24
which engages with helical spline
22
. Torque which is transmitted from the output shaft
20
to the drive portion
24
is transmitted from the drive portion
24
through rollers
25
to an inner or driven portion
26
. The driven portion
26
rotates a pinion shaft
27
which is integral with the driven portion
26
.
A pinion
29
engages with a straight external spline
28
which is formed on the end of the pinion shaft
27
. When the one-way clutch
23
is moved in the axial direction of the pinion shaft
27
by an unillustrated shift lever, the pinion
29
is moved in the axial direction of the pinion shaft
27
while rotating in accordance with the lead angle of helical spline
22
, and it engages with an unillustrated ring gear of an engine. A stopper
30
for preventing the pinion
29
from coming off the pinion shaft
27
is mounted on the pinion shaft
27
by a ring
32
in the manner shown in
FIG. 8
, which is a cross-sectional view of the right end of the pinion shaft
27
. A spring
31
presses the pinion
29
towards the stopper
30
. Helical spline
22
spirals in the opposite rotational direction from the direction in which the output shaft
20
is rotated by the electric motor.
In the apparatus of
FIGS. 7 and 8
, when the unillustrated shift lever moves the one-way clutch
23
to the right in
FIG. 7
, the one-way clutch
23
moves together with the pinion
29
while rotating in accordance with the lead angle of helical spline
22
, the pinion
29
engages with the unillustrated ring gear of the engine, and the internal combustion engine is started. If the teeth surfaces of the pinion
29
and the ring gear collide without meshing, the spring
31
is bent by the movement of the pinion shaft
27
, the pinion
29
rotates in accordance with the lead angle of helical spline
22
to complete engagement with the ring gear, and when engagement is completed, the electric motor is energized and starts the internal combustion engine.
In the starting apparatus illustrated in
FIG. 6
, when the pinion
12
is moved in the axial direction of the pinion shaft
10
, if the corners of the teeth of the pinion
12
contact the corners of the teeth of the ring gear
19
or a portion of the ring gear
19
which has been damaged during use, when the pinion
12
is further pushed by the shift lever
18
, the corners of the pinion
12
bite into the corners or a damaged portion of the ring gear
19
, and there are cases in which the pinion
12
cannot rotate in accordance with the lead angle of helical splines
11
or
13
. Particularly when the lead angle of helical spline
13
is large, as in the apparatus of
FIG. 6
, the component of force in the rotational direction with respect to the force in the axial direction is small, so rotation becomes impossible, and there are cases in which meshing of the pinion
12
with the ring gear
19
becomes impossible.
In such a situation, in order to again perform starting operation, if power to the electric motor is turned off, the shift lever
8
returns, and the pinion
12
and the pinion shaft
10
return to their original positions under the pressing force of the pinion return spring
17
. This return movement is accompanied by the rotation of the pinion
12
in accordance with the lead angle of helical spline
11
in the same rotational direction as the direction in which the pinion shaft
10
is rotated by the electr
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