Reverse input blocking clutch and clutch device using the same

Details Reverse input blocking clutch and clutch device using the same Reverse input blocking clutch and clutch device using the same

2002-03-07

2004-02-24

Bonck, Rodney H. (Department: 3681)

192 clutches and power-stop control

Transmission and brake

Torque-responsive brake

C359S877000

Reexamination Certificate

active

06695118

ABSTRACT:

BACKGROUND OF THE INVENTION
In devices which perform a desired operation by transmitting input torque from a rotational driving source such as a motor to an output mechanism, when the driving source is stopped, there are occasions in which it is desirable to block the transmission of reverse input torque from the output mechanism back to the input side.
An example of such an occasion is when a retention function is employed to prevent the position of the output mechanism fluctuating when the driving source is stopped. In this type of device, taking an electric shutter as an example, the input torque from the driving motor in either a forward or reverse direction is input to an opening and closing mechanism on the output side, which then performs the operation for either opening or closing the shutter, although if for some reason (such as a power failure or the like) the driving motor is stopped partway through the opening or closing operation, reverse input torque resulting from the descent of the shutter under its own weight is returned to the input side, resulting in the possibility of damage to the input side components. Consequently, a mechanism is required which holds the position of the shutter, and prevents the return of reverse input torque from the shutter to the input side.
Furthermore, in a construction in which a reduction gear is used to reduce the revolutions of a motor, the following problems may arise in those cases where, for some reason, torque is reverse input from the output side.
(a) In a case in which worm gearing is used as the reduction gear, then because rotation under reverse input is impossible with this type of worm gearing, a very large load is exerted on the worm wheel or the teeth of the worm. In particular, a very large thrust loading acts upon the worm. As a result, there is a danger of damage to the bearing supporting the teeth and the worm, or alternatively, the mechanism must be increased in size in order to prevent this type of damage.
(b) Even in the case of a reduction gear which utilizes a spur gear or a helical gear, there is still a possibility of damage to the teeth in those cases where the reverse input torque becomes excessively large (such as the case of a shocking reverse input).
In order to resolve the problems outlined above, a mechanism is required which is capable of transmitting input torque from the motor of the input side to the output side, but also capable of locking the output side with respect to reverse input torque from the output side, thereby preventing the return of reverse input torque to the motor or the reduction gear on the input side.
Furthermore in recent years, many vehicles including automobiles hive been equipped with motor driven electric retractable door mirrors, wherein the mirror moves through an angle of approximately 90° between a working position in which the mirror protrudes out from the side of the vehicle, and a retracted storage position. A conventional electric retractable door mirror (such as that disclosed in Japanese Patent Laid-Open Publication No. Hei 11-51092) utilizes a driving mechanism such as that shown in
FIG. 29
, wherein a mirror
42
can be moved easily by driving a motor
41
, but when an external force acts upon the mirror
42
, a clutch
43
effectively blocks the external force, holding the mirror
42
firmly in place and preventing the external force from acting upon the motor
41
.
However, in the driving mechanism disclosed in the above publication, because the mirror is securely fixed and undergoes no rotation even if an external force results in a reverse input torque acting upon the mirror, the mechanism is unable to absorb such an external force, and the mirror is consequently prone to damage. In order to resolve this problem, a mechanism is required which is capable of transmitting input torque from the motor of the input side to the mirror of the output side, but also permits the mirror to slip with respect to reverse input torque, thereby blocking the transmission of such reverse input torque back to the input side.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a reverse input blocking clutch which has the functions described above, and yet is compact, lightweight and low cost, as well as a clutch device using such a reverse input blocking clutch.
In order to achieve this object, a reverse input blocking clutch of the present invention comprises an input member into which torque is input, an output member to which torque is output, a stationary member for constraining the revolutions, locking means provided between the stationary member and the output member for locking the output member and the stationary member with respect to reverse input torque from the output member, lock release means provided on the input member for releasing a locked state produced by the locking means with respect to input torque from the input member, and torque transmission means provided between the input member and the output member for transmitting input torque from the input member to the output member when the locked state produced by the locking means is released, wherein at least the input member from amongst the input member, the output member and the stationary member is produced by deformation processing of a metal plate.
The “locking means” described above incorporates a device which applies an antirotation force by means of a wedge engagement force, an engagement between concave and convex surfaces, frictional force, magnetic force, electromagnetic force, fluid pressure, fluid viscosity resistance or a fine particle medium or the like, although from the viewpoints of cost, the simplicity of the structure and the control mechanism, and the smoothness of operation a device which applies an antirotation force by means of a wedge engagement force is preferred. Specifically, a wedge shaped gap is formed between the output member and the stationary member, and an engagement member is then either engaged into, or disengaged from this gap to switch the device between a locked state and a slipping state respectively. Furthermore, this type of construction includes Structures in which a cam surface for forming the wedge shaped gap is provided on either the output member or the stationary member (and an engagement member with a circular cross section such as a roller or a ball is used), and structures in which a cam surface for forming the wedge shaped gap is provided on the engagement member (and a sprag or the like is used as the engagement member).
Furthermore, the “metal plate” described above may be any metal plate capable of being shaped by deformation processing to the desired shape and dimensions. There are no particular restrictions on the material used, and a steel plate is a suitable example. Furthermore, the deformation processing can utilize techniques such as press working.
According to the above construction, when input torque is input at the input member, first the locked state produced by the locking means is released by the lock release means, and with the device in this released state, the input torque from the input member is transmitted to the output member via the torque transmission means. In contrast, a reverse input torque from the output member is locked between the output member and the stationary member by the locking means. Accordingly, a function is achieved wherein input torque from the input side is transmitted to the output side, whereas reverse input torque from the output side is not returned to the input side. Furthermore, by producing at least the input member from amongst the input member, the output member and the stationary member, from a metal plate which has undergone deformation processing, then in comparison with forged products, cast products or cutout products, the device is more compact, lighter, and cheaper to produce.
In the above construction, a connector can be provided for connecting an input shaft to the input member, and this connector can be positioned inside the clutch. As a result, the dimensions of th

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