In an aspect, the invention is directed to a clutched device that includes a clutch input member, a clutch output member, and a wrap spring clutch. The wrap spring clutch is engageable with the clutch input member and the clutch output member and has a radially outer surface and a radially inner surface. One of the radially outer and inner surfaces is engageable with a clutch engagement surface on one of the clutch input member and the clutch output member. The clutch engagement surface has a surface finish that includes peaks and valleys, wherein the peaks engage the wrap spring clutch and each have a selected width.

In an aspect a system is provided for generating vacuum in a vehicle. The system includes a vacuum pump, an engagement clutch, an actuator, and a torque limiting clutch. The e engagement clutch operatively connects a camshaft to the rotor. The actuator controls the clutch. The actuator is movable, based on air pressure in a vacuum conduit, between a low-pressure position in which the actuator causes the clutch to operatively disconnect the camshaft from the rotor, and a high-pressure position in which the actuator causes the clutch to operatively connect the camshaft to the rotor. The torque limiting clutch limits torque transfer to the rotor when the engagement clutch operatively connects the camshaft to the rotor. The system also provides control hysteresis.

In an aspect a system is provided for generating vacuum in a vehicle. The system includes a vacuum pump, an engagement clutch, an actuator, and a torque limiting clutch. The e engagement clutch operatively connects a camshaft to the rotor. The actuator controls the clutch. The actuator is movable, based on air pressure in a vacuum conduit, between a low-pressure position in which the actuator causes the clutch to operatively disconnect the camshaft from the rotor, and a high-pressure position in which the actuator causes the clutch to operatively connect the camshaft to the rotor. The torque limiting clutch limits torque transfer to the rotor when the engagement clutch operatively connects the camshaft to the rotor. The system also provides control hysteresis.

A clutch system includes a rotary input member, a wrap spring clutch and a rotary output member. The wrap spring clutch has a first end, a second end, and a plurality of coils. The stiffness of the wrap spring clutch is selected such that, when transmitting less than a selected coil engagement torque, the clutch system transmits torque helically from the rotary input member, to the second end, helically through the wrap spring clutch to the first end, and into the rotary output member. When transmitting more than the selected coil engagement torque, the clutch system transmits torque in parallel from the rotary input member, to the second end, helically through the wrap spring clutch to the first end, and into the rotary output member, and from the rotary input member through the coil engagement surface, to the first end, and into the rotary output member.

A decoupler having an input member, an output member and a combination one-way clutch and torsional isolator that couples the input and output members. The combination one-way clutch and torsional isolator includes a single helical coil spring. The decoupler being designed to provide torsional damping through a range of torque transmitted through the decoupler, the range including a maximum rate torque for the decoupler.

A decoupler having an input member, an output member and a combination one-way clutch and torsional isolator that couples the input and output members. The combination one-way clutch and torsional isolator includes a single helical coil spring. The decoupler being designed to provide torsional damping through a range of torque transmitted through the decoupler, the range including a maximum rate torque for the decoupler.

Clutch assemblies that can provide variable break-away torques are described. An exemplary multi-state clutch assembly can include a shaft, a first frictional element frictionally engaged with the shaft and a second frictional element that can provide variable friction. When the second frictional element provides a low friction, second frictional element can be rotatable relative to the first frictional element, which can remain stationary relative to the shaft. When the second frictional element provides a high friction, it can be secured to the first frictional element. Hence, the first and second frictional elements can be locked together and be rotatable relative to the shaft. Tightening or loosening the second frictional element can vary the overall break-away torque provided by the clutch assembly. The multi-state clutch assembly can be in communication with a sensor or a switch that can respond to a user to change the friction of the clutch assembly.

A torque limiter (120) includes a coil spring (124), an inner shaft which is connected to a drive shaft (58) and is disposed to be inserted into a coil portion of the coil spring (124) so that the coil portion of the coil spring (124) is configured to come into close contact with an outer peripheral surface, a bottomed cylindrical outer member (122) which is disposed at the outside of the coil portion with a gap interposed therebetween and is provided relatively rotatable with respect to the inner shaft so that both end portions of a wire forming the coil spring (124) are locked thereto, and a drive gear (123) which is integrally formed with a plate portion (122a) of the outer member (122) and is configured to transmit a rotational force to the screw shaft.

A driving force transmission mechanism includes a first transmission member and a second transmission member that are arranged on an identical rotational center axis. The first transmission member includes one or more transmission claws engaged with the second transmission member. The transmission claw includes, at a position away from the rotational center axis, a fixing portion with respect to the first transmission member, and extends in a direction crossing a direction directed from the fixing portion to the rotational center axis. The second transmission member includes one or more stoppers engaged with a tip end of the transmission claw and one or more holding portions engaged with a side of the transmission claw, which faces the rotational center axis.