Motor having clutch and manufacturing method thereof

Details Motor having clutch and manufacturing method thereof Motor having clutch and manufacturing method thereof

2001-05-23

2003-04-22

Bonck, Rodney H (Department: 3681)

192 clutches and power-stop control

Transmission and brake

Torque-responsive brake

C029S596000, C310S049540, C310S077000, C310S083000

Reexamination Certificate

active

06550599

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-168784 filed on Jun. 6, 2000 and Japanese Patent Application No. 2001-118997 filed on Apr. 18, 2001.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor having a rotatable rotor shaft (rotatable shaft) coupled with a worm shaft via a clutch and also to a manufacturing method of such a motor.
2. Description of Related Art
With reference to
FIG. 12
, one previously proposed motor used, for example, in a vehicle power window system includes a motor main body
82
, an output arrangement
84
and a clutch
85
(FIG.
13
). The motor main body
82
has a rotatable shaft
81
that is rotated upon energization of the motor. The output arrangement
84
has a worm shaft
83
. The clutch
85
transmits rotation of the rotatable shaft
81
to the worm shaft
83
but prevents transmission of rotation of the worm shaft
83
to the rotatable shaft
81
.
As shown in
FIG. 13
, the clutch
85
includes a driving-side rotator
86
, a driven-side rotator
87
, a collar
89
and rolling elements
90
. The driving-side rotator
86
is secured to a distal end of the rotatable shaft
81
in non-rotatable relationship with respect to the rotatable shaft
81
. The driven-side rotator
87
is securely connected to a base end of the worm shaft
83
in non-rotatable relationship with respect to the worm shaft
83
. The collar
89
is secured to a gear housing
88
of the output arrangement
84
to surround both the driving-side rotator
86
and the driven-side rotator
87
. The rolling elements
90
are positioned between the driven-side rotator
87
and the collar
89
.
At an axial center of the driving-side rotator
86
, there is provided an annular recess
86
a
having diametrically opposing flat inner surfaces. Furthermore, at the distal end of the rotatable shaft
81
, there is provided an annular protrusion
81
a
having diametrically opposing flat outer surfaces. When the protrusion
81
a
is fitted within the recess
86
a
, the rotatable shaft
81
is secured to the driving-side rotator
86
. The inner surfaces of the annular recess
86
a
are tapered such that a width of the recess
86
a
increases toward an opening (upper side in
FIG. 13
) of the recess
86
a
to facilitate insertion of the protrusion
81
a
into the recess
86
a
during assembly.
Protrusions
86
b
are formed on a worm shaft
83
side of the driving-side rotator
86
at predetermined angular positions at radially outward region of the driving-side rotator
86
. Each protrusion
86
b
axially protrudes toward the worm shaft
83
and extends radially outwardly. A plurality of recesses
87
a
are formed at predetermined angular positions at a radially outward region of the driven-side rotator
87
. A radially inward portion (where a rubber component G is arranged) of each protrusion
86
b
is received within the corresponding recess
87
a
of the driven-side rotator
87
in such a manner that a predetermined circumferential space is provided between each protrusion
86
b
and the corresponding recess
87
a
. Control surfaces
87
b
are provided in radially outer surfaces of protruded portions of the driven-side rotator
87
that are formed between the recesses
87
a
. A radial space between an inner peripheral surface of the collar
89
and each control surface
87
b
varies in a circumferential direction. Each rolling element
90
is arranged between the corresponding control surface
87
b
and the inner peripheral surface of the collar
89
.
An annular disk portion
89
a
that extends radially inwardly is formed at one end (upper end in
FIG. 13
) of the collar
89
. An annular cover plate
91
is fitted within the other end (lower end in
FIG. 13
) of the collar
89
. The cover plate
91
and the annular disk portion
89
a
cooperate to limit axial relative movement of the driving-side rotator
86
, the driven-side rotator
87
and the rolling elements
90
. More specifically, an inner diameter of the annular disk portion
89
a
is selected such that the annular disk portion
89
a
prevents the driving-side rotator
86
to pass through it. Likewise, an inner diameter of the cover plate
91
is selected such that the cover plate
91
prevents the driven-side rotator
87
to pass through it. The other end of the collar
89
(lower end in
FIG. 13
) is securely fitted within a serrated annular groove
88
a
formed in the gear housing
88
.
The motor having the above-described structure is assembled as follows.
First, with reference to
FIG. 14
, the driving-side rotator
86
, the rolling elements
90
and the driven-side rotator
87
that is previously connected to the worm shaft
83
are inserted inside of the collar
89
from the other end of the collar
89
. Then, the cover plate
91
is fitted to prevent these components from falling out of the collar
89
. In this way, a clutch-worm shaft unit
92
is assembled. Then, a sensor magnet
93
that constitutes a rotational sensor is secured around a shaft portion of the driving-side rotator
86
which protrudes from the collar
89
.
Next, the worm shaft
83
of the clutch-worm shaft unit
92
is received within a worm shaft receiving recess
88
b
defined within the gear housing
88
. More specifically, the worm shaft
83
of the clutch-worm shaft unit
92
is received within a pair of metal bearings
94
retained within the worm shaft receiving recess
88
b
. During this process, the collar
89
of the clutch-worm shaft unit
92
is clamped by a human hand or chuck claws of a manufacturing device (not shown) to insert the worm shaft
83
of the clutch-worm shaft unit
92
into the worm shaft receiving recess
88
b
. Then, the other end of the collar
89
is fitted within the serrated annular groove
88
a.
Thereafter, as shown in
FIG. 15
, a yoke
95
of the motor main body
82
is connected to the gear housing
88
of the output arrangement
84
, and the protrusion
81
a
of the rotatable shaft
81
is fitted within the recess
86
a
of the driving-side rotator
86
to securely connect the rotatable shaft
81
to the driving-side rotator
86
.
In the clutch
85
of the assembled motor, when the motor main body
82
is energized or driven to rotate the rotatable shaft
81
and thereby the driving-side rotator
86
, each rolling element
90
is pushed by a radially outward portion of the corresponding protrusion
86
b
, and a wall surface of each recess
87
a
of the driven-side rotator
87
is pushed by a radially inward portion of the corresponding protrusion
86
b
. As a result, the driven-side rotator
87
and the worm shaft
83
are rotated by the driving-side rotator
86
.
On the other hand, in a non-actuated state of the motor main body
82
, if the driven-side rotator
87
is forcefully rotated along with the worm shaft
83
, each rolling element
90
is clamped between the corresponding control surface
87
b
and the inner peripheral surface of the collar
89
to prevent further rotation of the driven-side rotator
87
(locked state).
While the driven-side rotator
87
is provided as the clutch-worm shaft unit
92
(i.e., while the driven-side rotator
87
is not installed in the gear housing
88
), there is a small play between the driven-side rotator
87
and the other clutch components (such as driving-side rotator
86
, cover plate
91
or the like), and thereby the driven-side rotator
87
can slightly tilt relative to the collar
89
.
Thus, when the collar
89
of the clutch-worm shaft unit
92
is clamped to insert the worm shaft
83
within the metal bearings
94
, the worm shaft
83
may swing freely, so that, for example, a worm
83
a
(tooth) of the worm shaft
83
may contact an inner peripheral surface of the corresponding metal bearing
94
(the contact surface between the worm shaft
83
and the metal bearing
94
), resulting in damage to the inner peripheral surface of the metal bearing
94
.
SUMMARY OF THE INVENTION
The present invention addresses the above described d

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