The disclosures of the following priority applications are herein incorporated by references:

Japanese Patent Application No. 2020-056149, and

Japanese Patent Application No. 2021-008822.

TECHNICAL FIELD

The present invention relates to a clutch apparatus, and in particular an excessive torque releasing type clutch apparatus, that is used for the purpose of transmission of torque, backstop and the like in vehicles and industrial machines.

BACKGROUND ART

As a clutch apparatus that can change over torque transmitting direction, a ratchet type clutch apparatus has been known. In such a ratchet type clutch apparatus, a rotation in either direction of a relative rotation of an outer ring to an inner ring is locked transmitting torque. Such a locking of the relative rotation is conducted by pawl members received in either one of the outer ring or inner ring being engaged with splined portions formed in the other of the outer ring and the inner ring. There are concerns in such ratchet type clutch apparatus that quietness would be deteriorated due to impact noise upon engagement as well as durability of constituent members would be deteriorated due to impact torque.

With respect to such problems, Patent Literature 1 discloses an impact absorbing member that reduces impact noise. Patent Literature 2 discloses a configuration for softening impact torque stress to be adopted in portions of the outer ring or inner ring at which pawl members are received.

A sprag type clutch apparatus is known as another type clutch apparatus. The sprag type clutch apparatus comprises an annular outer race, an annular inner race and sprags disposed therebetween, wherein when the outer ring and the inner ring rotate relative to each other, the sprags are brought into engagement with the outer ring and the inner ring regarding one of directions of the relative rotation to lock them and transmit torque therebetween. In the sprag type clutch apparatus, generation of impact noise upon engagement is smaller compared with the ratchet type clutch apparatus. However, with respect to capacity of the clutch apparatus in itself, and capacity of the outer ring and the inner ring against impact torque like an inverse input torque, it is necessary to secure strength of parts in accordance with torque.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Patent Application Laid-Open No. 2003-056605

Patent Literature 2: Japanese Patent Application Laid-Open No. 2019-127989

SUMMARY OF INVENTION

Technical Problem

Even if techniques disclosed in the above Patent Literatures 1 and 2 are adopted in a ratchet type clutch apparatus, very special heat treatment such as carburizing treatment is required in order to secure necessary strength of constituent parts against impact torque, taking in consideration of unexpected excessive torque in abnormal mode. However, it is desirable to avoid or simplify such treatment in view of reducing manufacturing costs or the number of processing steps.

On the other hand, in case of a sprag type clutch apparatus also, if, for example, thickness in circumferential direction of the outer or inner ring is made large in order to secure strength of the outer or inner ring as countermeasure against impact torque, space and weight thereof would be increased. Moreover, special processing or treatment such as shot peening depending on strength requirement onto the outer and inner rings, will be required as in the case of the ratchet type clutch apparatus, and therefore it is desirable to simplify or eliminate such special processing or treatment in view of reducing manufacturing costs or the number of processing steps.

Taking the above described circumstances into consideration, an object of the present invention is to provide an excessive torque releasing type clutch apparatus, which can release excessive torque upon being input thereto, so that treating step for securing strength of constituent parts when manufacturing may be simplified or eliminated.

Solution to Problem

To solve the above object, according to the present invention, there is provided a clutch apparatus comprising:

an outer ring,

an inner ring disposed radially inside the outer ring and in coaxial with a center axis of the outer ring and rotatably relative to the outer ring,

a torque transmitting portion that is capable of transmitting torque having a center on the center axis between the outer ring and the inner ring, and

a restricting mechanism which restricts a transmission of input torque that exceeds a predetermined value from an input torque transmitting member to a driving ring of the outer ring and the inner ring, and a transmission of reverse input torque that is input to a driven ring of the outer ring and the inner ring and exceeds a predetermined torque, to the input torque transmitting member.

Advantageous Effect of the Invention

The present invention can provide an excessive torque releasing type clutch apparatus, which can release excessive torque upon being input thereto, and of which constituent parts can be manufactured with special heat treatment for securing strength being simplified or eliminated.

