The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
One way or overrunning clutches provide a unique operational capability in mechanical power transmission equipment. In their most basic configuration, coaxial first and second members allow relative rotation between them in one direction but lock or connect the members when relative rotation in the opposite direction is attempted. These devices frequently take the form of inner and outer concentric members with pawls, sprags, struts or rockers obliquely disposed therebetween which release the members in one direction of relative rotation and lock them together in the opposite direction of relative rotation.
Other clutch configurations such as selectable one way clutches (SOWC), as the name implies, achieve such one way or overrunning operation in both directions, the overrunning and locking directions being selectable by an associated control device. A difficulty with such devices arises when it is necessary to reverse the one way or overrunning operation from one direction of relative rotation to the other. Before such reversal can be accomplished, all or substantially all torque across the clutch must be removed as it is the torque across the clutch that locks and maintains engagement of the struts or pawls. Generally speaking, the solution to this problem requires that all or substantially all torque through the clutch be eliminated and the force be removed from the pawls or struts by stopping rotation of the device. While in the condition of negligible torque throughput, the sense of the device can be reversed, the time and conditions necessary to achieve this reversal may interfere with other operational aspects of the transmission.
The present invention addresses this difficulty.