Patent ID: 8286771

Claim:
A rotational direction switching clutch unit comprising an input gear ( 12 ), an output gear ( 13 ) and a reverse input gear ( 14 ) which are coaxially arranged in the axial direction, and a spring clutch ( 26 , 26 a ); wherein said input gear ( 12 ) includes an input clutch portion ( 15 , 15 a ), and said output gear ( 13 ) includes an output clutch portion ( 16 , 16 a ) that radially opposes said input clutch portion ( 15 , 15 a ); wherein said spring clutch ( 26 , 26 a ) comprises coil springs ( 27 and 27 â€², 27 a and 27 â€² a ) tightly bound to said input clutch portion ( 15 , 15 a ) and having such directivity that said spring clutch is locked when the input clutch portion ( 15 , 15 a ) rotates in a forward rotational direction A, each of said coil springs ( 27 and 27 â€², 27 a and 27 â€² a ) having a transmission hook ( 28 ) at one end thereof and a release hook ( 29 ) at another end thereof, wherein with said transmission hooks ( 28 ) in engagement with a hook engaging portion ( 21 , 21 a ) of the output clutch portion ( 16 , 16 a ), said release hooks ( 29 ) are spaced by a predetermined distance from said transmission hooks ( 28 ) in the forward rotational direction A; wherein said reverse input gear ( 14 ) has a release portion ( 24 , 24 a ) axially protruding into a space between the input clutch portion ( 15 , 15 a ) and the output clutch portion ( 16 , 16 a ) and opposed to said release hooks ( 29 ) in a reverse rotational direction B; and wherein when said release portion ( 24 , 24 a ) is rotated in the reverse rotational direction B by a distance c from an unlocking starting state in which the release portion ( 24 , 24 a ) is in contact with the release hooks ( 29 ) while pushing the release hooks ( 29 ), said spring clutch ( 26 , 26 a ) is configured to be unlocked, and when said release portion ( 24 , 24 a ) is rotated in the reverse rotational direction B by a distance a from said unlocking starting state while pushing said release hooks ( 29 ), said release portion ( 24 , 24 a ) is configured to engage said hook engaging portion ( 21 , 21 a ), said distance a being greater than said distance c (a>c).