192 clutches and power-stop control – Clutches – Automatic
Reexamination Certificate
2001-05-30
2002-09-03
Rodriguez, Saul (Department: 3681)
192 clutches and power-stop control
Clutches
Automatic
C192S11000B, C474S170000
Reexamination Certificate
active
06443280
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a roller clutch built-in type pulley apparatus for an alternator to be used in an automobile.
A roller clutch built-in type pulley apparatus for an alternator to be provided by the present invention is fixed to an end portion of the rotary shaft of the alternator which serves as a power generator for a car for wrapping an endless belt onto a driving pulley fixed to an end portion of a crank shaft of the engine, so as to be utilized for driving the alternator. Particularly, the present invention is to realize a useful structure when using a so-called poly-V belt in which a plurality of projections each having a V-shaped cross section are extending along the entire circumference are provided on the inner peripheral surface thereof as the above-mentioned endless belt.
2. Related Background Art
The structure of an alternator for generating necessary electric power for a car by use of a driving engine of the car as its driving source is disclosed in, for example, Japanese Patent Laid-Open No. 7-139550.
FIG. 5
shows an alternator
1
disclosed in this application. In the alternator
1
, a rotary shaft
3
is rotatably supported by a pair of rolling bearings
4
,
4
inside the housing
2
. In a middle part of this rotary shaft
3
, there are provided a rotor
5
and a commutator
6
. Also, a pulley
7
is fixed to a portion projecting outward from the housing
2
at one end (the right end in
FIG. 5
) of this rotary shaft
3
. In a state in which it is assembled in the engine, an endless belt is passed over this pulley
7
, so that the rotary shaft
3
is rotated and driven by means of a crank shaft of the engine.
As this pulley
7
, hitherto a pulley which is simply fixed to the rotary shaft
3
is generally used. However, a variety of kinds of a roller clutch built-in type pulley apparatus for an alternator are proposed recently, which allows transmission of the power through the endless belt to the rotary shaft when a running speed of the endless belt is fixed or shows an upward trend, while allows a relative rotation between the pulley and the rotary shaft when the running speed of the endless belt shows downward trend. Some of such pulley apparatuses are used in practice. For example, a several kinds of such roller clutch built-in type pulley apparatus for an alternator having a function as mentioned above are disclosed in Japanese Patent Laid-Open Nos. 56-101353, 7-317807, 8-61443, and 8-226462, and Patent Publication No. 7-72585, French Patent Publication No. FR2726059A1, etc. Also, some of such roller clutch built-in type pulley apparatuses are actually used in practice.
Out of them,
FIG. 6
shows the roller clutch built-in type pulley apparatus for an alternator disclosed in Japanese Patent Laid-Open No. 8-226462. This roller clutch built-in type pulley apparatus for an alternator has a sleeve
8
which is fitted on and fixed to the rotary shaft
3
of the alternator
1
(FIG.
5
). Around this sleeve
8
, a pulley
7
a
is provided concentrically with this sleeve
8
. On the outer peripheral surface of this pulley
7
a, there are formed a plurality of grooves
29
,
29
each having V-shaped cross section and extending along the entire circumference in parallel to each other in the axial direction (the left and right direction in FIG.
6
). An endless belt which is so-called a poly-V belt and which has a plurality of projections each having a V-shaped cross section and extending along the entire circumference on the inner peripheral surface of the belt is passed over such pulley
7
a.
Then, a pair of support bearings
9
,
9
and a roller clutch
10
are provided between the outer peripheral surface of the sleeve
8
and the inner peripheral surface of the pulley
7
a
. Out of them, the support bearings
9
,
9
cause a relative rotation between the sleeve
8
and the pulley
7
a
, while supporting a radial load applied on the pulley
7
a
. On the other hand, the roller clutch
10
causes transmission of the rotating force from this pulley
7
a
to the sleeve
8
only when the pulley
7
a
is inclined to rotate relatively to the sleeve
8
in a given direction. In the structure shown in
FIG. 6
, the support bearings
9
.
9
are cylindrical roller bearings. However, angular or deep groove ball bearings are conventionally known as being used as such support bearings, as disclosed, for example, in the above Japanese Patent Laid-Open No. 7-317807.
On the outer peripheral surface of the middle part of the inner race
24
which constitutes the roller clutch
10
and is fitted on and fixed to the sleeve
8
, a plurality of recesses
25
called a ramp portion are formed at regular intervals in the circumferential direction, while a cam surface
26
is formed on the outer peripheral surface of the middle part. The outer peripheral surfaces of the both ends of the inner race
24
serve as inner race tracks
27
,
27
for the support bearings
9
,
9
. On the other hand, the inner peripheral surface of the outer race
12
which constitutes the roller clutch
10
and is fitted on and fixed to the pulley
7
a
is simply formed as a cylindrical surface substantially over the entire length thereof. A plurality of rollers
11
,
11
for constituting the roller clutch
10
, together with the inner race
24
and the outer race
12
, are supported by a retainer
28
to be capable of rolling and displacing a little in the circumferential direction. Then, there is provided a spring between a column portion arranged on this retainer
28
and each of the rollers
11
so that each of the rollers
11
is elastically pressed in the same direction with respect to the circumferential direction.
A roller clutch built-in type pulley apparatus for an alternator as mentioned above is used for the following reason. If, for example, the driving engine is a diesel engine, the angular velocity of rotation fluctuates largely when the engine is idling or rotated at low speed. As a result, the running speed of the unrepresented endless belt which is passed over the driving pulley fixed to the end of the crank shaft fluctuates minutely. On the other hand, the rotary shaft
3
of the alternator
1
which is driven to rotate by this endless belt through the pulley
7
a
does not fluctuate so drastically due to the inertial masses of this rotary shaft
3
and the rotor
5
, the commutator
6
(FIG.
5
), and the like fixed to this rotary shaft
3
. Accordingly, when the pulley
7
a
is simply fixed with respect to the rotary shaft
3
, the endless belt and the pulley
7
a
are inclined to rub against each other in the both directions upon fluctuation of the angular velocity of rotation of the crank shaft. As a result, the stress in different directions acts repeatedly on the endless belt which rubs against the pulley
7
a
, which causes easy slippery between this endless belt and the pulley
7
a
, or a shortened durability of the endless belt.
The shortened durability of the endless belt based on the friction between the outer peripheral surface of the pulley
7
a
and the inner peripheral surface of the endless belt as described above is also caused by repeated acceleration or deceleration at running time. That is, the driving force is transmitted from the endless belt side to the pulley
7
a
side at acceleration, while the braking force acts from the endless belt onto the pulley
7
a
which intends to continuously rotate based on inertia at deceleration, as described above. The braking force and the driving force respectively act as frictional forces in opposite directions for the inner peripheral surface of the endless belt, which also causes reduction in durability of the endless belt as a result. Particularly, in case of a vehicle equipped with an exhaust brake such as a motor truck, the rotation of the crank shaft when the accelerator is off is conspicuously decelerated, and the frictional force applied on the inner peripheral surface of the endless belt becomes large based on the above-mentioned braking force. As a
Crowell & Moring LLP
NSK Ltd.
Rodriguez Saul
LandOfFree
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