192 clutches and power-stop control – Clutches – Automatic
Reexamination Certificate
2002-02-13
2002-10-15
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Automatic
C192S11000B
Reexamination Certificate
active
06464057
ABSTRACT:
FIELD OF THE INVENTION
An alternator pulley unit with a built-in one-way clutch of the present invention is utilized for driving an alternator serving as a generator for vehicles, by fixing the pulley unit to an end of a rotation shaft of the alternator, and spanning an endless belt between the pulley unit and a drive pulley fixed to an end of a crank shaft of an engine.
BACKGROUND OF THE INVENTION
A structure of an alternator for generating electric power required for an automobile using the automobile propulsion engine as a drive source is described for example in Japanese Patent Publication No. Tokukai Hei7-139550.
FIG. 5
shows the alternator described in this Application. A rotation shaft
3
is rotatably supported inside a housing
2
by a pair of rolling bearings
4
. A rotor
5
and a commutator
6
are disposed on an intermediate part of the rotation shaft
3
. In addition, a driven pulley
7
is fixed to a portion protruding toward the outside of the housing
2
, at one end (the right end in
FIG. 5
) of the rotation shaft
3
. In the condition where it is assembled into an engine, an endless belt is spanned around the driven pulley
7
, and the rotation shaft
3
is freely rotated by the engine crank shaft.
For the above described driven pulley
7
, one which is simply fixed to the rotation shaft
3
has heretofore been used. On the other hand, various kinds of alternator pulley unit with a built-in one-way clutch have been proposed and used in part, such as one in which when the running speed of the endless belt is constant or tends to increase, motive power is freely transmitted from the endless belt to the rotation shaft, while when the running speed of the endless belt tends to decrease, the driven pulley and the rotation shaft are freely rotatable relative to each other. An alternator pulley unit with a built-in one-way clutch having functions described above, is described for example in Japanese Patent Publication Nos. Tokukai Sho56-101353, Tokukai Hei7-317807, Tokukai Hei8-614431) Tokukai Hei10-285873, Japanese Patent Publication No. Tokuko Hei 7-72585, France Patent Publication No. FR2726059A1 and the like. Moreover, such an alternator pulley unit with a built-in one-way clutch has been actually used in part.
FIG. 6
shows an alternator pulley unit with a built-in one-way clutch described in Japanese Patent Publication No. Tokukai Hei10-285873. This alternator pulley unit with a built-in one-way clutch has a sleeve
8
that can be freely externally fitted and secured to a rotation shaft
3
(FIG. 5). A driven pulley
7
a
is then disposed concentric with the sleeve
8
around the sleeve
8
. In addition, a pair of support bearings
9
and a one-way clutch
10
are provided between an outer peripheral face of the sleeve
8
and an inner peripheral face of the driven pulley
7
a
. Of these, the support bearings
9
enable free rotation of the sleeve
8
and the driven pulley
7
a
relative to each other, while rotatably supporting a radial load applied to the driven pulley
7
a
.
Moreover, the one-way clutch
10
can transmit a turning force from the driven pulley
7
a
to the sleeve
8
only when the driven pulley
7
a
has a tendency to rotate in a predetermined direction relative to the sleeve
8
. Therefore, to construct the aforementioned one-way clutch
10
, a cam, face
12
is formed on an outer peripheral face of an intermediate portion of an inner ring
11
which is externally fitted and secured to the sleeve
8
. Furthermore, a plurality of rollers
13
are arranged between the outer peripheral face of the cam face
12
and the inner peripheral face of the driven pulley
7
a
. Then, between these rollers
13
and a retainer
14
for retaining these rollers
13
, there are provided a plurality of springs (not shown). These springs resiliently press the respective rollers
13
in a direction to make the respective rollers
13
encroach into a wedge shape at a portion where, of the dimensions of a cylindrical gap formed between the outer peripheral face of the cam face
12
and the inner peripheral face of the driven pulley
7
a
, the width across the diametral direction becomes narrow. Furthermore, a torque for pressing the respective rollers
13
based on the resilience is designated as 4 N•m or less.
According to the alternator pulley unit with a built-in one-way clutch described in the above described Japanese Patent Publication No. Tokukai Hei10-285873 constituted as described above, generating efficiency of the alternator can be ensured to some degree. That is to say, when the rotational speed of the engine increases, and the running speed of the endless belt
15
spanning between the drive pulley and the driven pulley
7
a
tends to increase, there is a tendency for the driven pulley
7
a
to rotate relative to the sleeve
8
in a predetermined direction. As a result, the respective rollers
13
encroach into the wedge shape (become locked) at the portion where, of dimensions of the cylindrical gap formed between the outer peripheral face of the inner ring
11
and the inner peripheral face of the driven pulley
7
a
, the width across the diametral direction becomes narrow, thereby enabling free transmission of the turning force from the driven pulley
7
a
to the rotation shaft
3
. On the other hand, when the rotational speed of the engine decreases, and the running speed of the endless belt
15
tends to decrease, the driven pulley
7
a
rotates relative to the sleeve
8
in the direction opposite to the above described predetermined direction. Therefore, the respective rollers
13
shift to a portion where the width of the above described cylindrical gap becomes wider, enabling free rolling of these respective rollers
13
in the concerned portion (giving an overrun state), so that the driven pulley
7
a
and the rotation shaft
3
can freely rotate relative to each other. At this time, since the respective rollers
13
are pressed by means of a torque of 4 N•m or less based oil the resilience of the aforesaid respective springs, shift from the locked state to the overrun state can be performed at a relatively early stage from when the running speed of the endless belt
15
starts to decrease. Since the shift to the overrun state is performed at a relatively early stage as described above, the rotation shaft
3
of the alternator can continue to rotate in a high region to some extent based on its own rotational force of inertia, regardless of variations in the rotational speed of the engine, so that the power generating efficiency of the alternator can be ensured to some degree.
In the case of the alternator pulley unit with a built-in one-way clutch described in Japanese Patent Publication No. Tokukai Hei10-285873 constituted and operated as described above, it still cannot be said that the power generating efficiency is sufficiently ensured. In addition, there is the possibility of the occurrence of abnormal sounds due to rubbing of the driven pulley
7
a
and the endless belt
15
against each other, and a decrease in the life span of the endless belt
15
cannot be sufficiently prevented. That is to say, since the crank shaft is rotated and driven based on intermittent explosions inside the engine cylinder, completely smooth rotational motion is not performed, and the turning angular velocity varies slightly even during one rotation. The variation in the turning angular velocity increases as the rotational speed of the engine decreases. As a result, the running speed of the endless belt
15
spanning to the drive pulley secured at the end of the crank shaft also varies slightly. Therefore, to ensure sufficient power generating efficiency of the alternator, it is necessary to make the pulley unit follow the slight variations in the running speed of the endless belt
15
, and to promptly perform the shift from the locked state to the overrun state when the running speed of the endless belt
15
tends to decrease.
On the other hand, even if the running speed of the endless belt
15
varies slightly as described above, the rotatio
Crowell & Moring LLP
Lorence Richard M.
NSK Ltd.
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