The invention relates to miniature drives for use in automobile locks. A return of the mechanism once the lock is opened and the motor is shut down is prevented completely mechanically. For this purpose, the worm wheel is associated with a mechanically active locking element which allows first to slightly turn back the wheel to unlock and reduce the load on the mechanism, but then prevents any further rotation against the direction of drive.

A distance between a rotation center of an input member and a contact portion between an input side engaging portion and an input side engaged portion in a second direction is set to be shorter than a distance between a rotation center of an output member and a contact portion between an output side engaging portion and an output side engaged portion in the second direction. In a locked or semi-locked state, a contact portion between the output side engaging portion and the output side engaged portion is located on the side closer to the rotation center of the output member in a first direction in relation to a virtual line connecting the rotation center of the output member and a contact portion between one pressing surface of the pair of pressing surfaces and the pressed surface.

A distance between a rotation center of an input member and a contact portion between an input side engaging portion and an input side engaged portion in a second direction is set to be shorter than a distance between a rotation center of an output member and a contact portion between an output side engaging portion and an output side engaged portion in the second direction. In a locked or semi-locked state, a contact portion between the output side engaging portion and the output side engaged portion is located on the side closer to the rotation center of the output member in a first direction in relation to a virtual line connecting the rotation center of the output member and a contact portion between one pressing surface of the pair of pressing surfaces and the pressed surface.

In a locking type reverse input blocking clutch, smooth finished surfaces having no directionality are formed, by barrel polishing, on surfaces brought into contact with rollers while rotation is being transmitted from the input side to the output side, i.e. an inner peripheral cylindrical surface of an outer ring and a surface of a lid portion opposed to the rollers. With this arrangement, it is possible to reduce the sliding resistance between the rollers and the outer ring and between the rollers and the lid portion, without the need to reduce the forces of springs for pushing the rollers into narrow portions of wedge-shaped spaces. This in turn makes it possible to reduce the torque necessary to transmit rotation from the input side to the output side, while maintaining high locking performance.

In a locking type reverse input blocking clutch, smooth finished surfaces having no directionality are formed, by barrel polishing, on surfaces brought into contact with rollers while rotation is being transmitted from the input side to the output side, i.e. an inner peripheral cylindrical surface of an outer ring and a surface of a lid portion opposed to the rollers. With this arrangement, it is possible to reduce the sliding resistance between the rollers and the outer ring and between the rollers and the lid portion, without the need to reduce the forces of springs for pushing the rollers into narrow portions of wedge-shaped spaces. This in turn makes it possible to reduce the torque necessary to transmit rotation from the input side to the output side, while maintaining high locking performance.

A brake-side clutch part to transmit a rotational torque input from a lever-side clutch part to an output side, and interrupt a rotational torque reversely input from the output side includes an inner ring, an outer ring including a recess/protrusion part, an output shaft, an engaging element including a recess/protrusion part capable of meshing with the recess/protrusion part, and a control mechanism to engage the engaging element with the outer ring through meshing between the recess/protrusion part and the recess/protrusion part when the rotational torque is interrupted, and disengage the engaging element from the outer ring through release of the meshing when the rotational torque is transmitted. The control mechanism includes a support part, which is provided between the engaging element and the inner ring, and is configured to maintain an engagement state between the engaging element and the outer ring when the rotational torque is interrupted.

A clutch unit includes a lever-side clutch part to control transmission and interruption of rotational torque input through a lever operation and a brake-side clutch part to transmit the rotational torque from the lever-side clutch part to the output side and interrupt rotational torque reversely input from the output side. The brake-side clutch part includes an outer ring constrained in rotation, an output shaft to output the rotation, cylindrical rollers to control interruption of the rotational torque reversely input from the output shaft and transmission of the rotational torque input from the lever-side clutch part through engagement and disengagement between the outer ring and the output shaft, a friction ring to apply a rotational resistance to the output shaft, and a variable part to change the rotational resistance applied to the output shaft between the transmission and the interruption of the rotational torque.

A clutch includes a roller arranged between a clutch housing and a driven side rotating body. The roller is rotated about a rotation axis of a drive side rotating body together with the drive side rotating body when the drive side rotating body is rotationally driven. The roller hinders rotation of the driven side rotating body by being sandwiched between the clutch housing and the driven side rotating body when the drive side rotating body is not rotationally driven. The support member sandwiches the roller between the clutch housing and the driven side rotating body. The support member rotates about the rotation axis of the drive side rotating body together with the drive side rotating body. The grease is arranged between the clutch housing and the roller. The support member restricts rotation of the roller about a central axis of the roller.

A fluid driving device, a motor assembly and a friction clutch thereof are disclosed. The friction clutch includes: a fixing member fixed on a rotary shaft; a connecting member slidable disposed on the rotary shaft, wherein when the rotary shaft starts rotating, an axial distance between the connecting member and the fixing member changes such that a friction force between the fixing member and the connecting member increases until the connecting member rotates synchronously with the fixing member; a loading member slidable disposed on the rotary shaft, the loading member and the connecting member being circumferentially positioned; and a restoring member configured to reduce an amount of change of the axial distance between the fixing member and the connecting member when the rotary shaft stops rotating.

A fluid driving device, a motor assembly and a friction clutch thereof are disclosed. The friction clutch includes: a fixing member fixed on a rotary shaft; a connecting member slidable disposed on the rotary shaft, wherein when the rotary shaft starts rotating, an axial distance between the connecting member and the fixing member changes such that a friction force between the fixing member and the connecting member increases until the connecting member rotates synchronously with the fixing member; a loading member slidable disposed on the rotary shaft, the loading member and the connecting member being circumferentially positioned; and a restoring member configured to reduce an amount of change of the axial distance between the fixing member and the connecting member when the rotary shaft stops rotating.