Patent ID: 9004251
Filing Date: 2015-04-14
Classification: F16D

Abstract:
1. An electromagnetic clutch, comprising: a driving-side rotation member rotating about a rotation axis as a center by receiving a driving force; a driven-side rotation member coaxially arranged with the rotation axis; a wrap spring being wound around to be in a pressure bonding state relative to the driving-side rotation member in a normal state; a driving member fixed to the driven-side rotation member, connected with a first end of the wrap spring; an operating member made from a magnetic body rotatable relative to the driven-side rotation member about the rotation axis as the center, movable along the rotation axis, including a disc form member formed in a disc form provided with a rim portion where a second end of the wrap spring connects to; an electromagnetic solenoid configured to generate a magnetic force attracting and retaining the operating member, wherein at a time at which electricity is supplied to the electromagnetic solenoid, which in turn attracts and retains the operating member to the electromagnetic solenoid, the driving member rotates relative to the operating member by a frictional force generated between the driving member and the driving-side rotation member or by inertia, which in turn cancels the wrap spring from the pressure boding state relative to the driving-side rotation member to disconnect power transmission from the driving-side rotation member to the driven-side rotation member; an intermediate member made from a magnetic body provided at a position opposite side of where the electromagnetic solenoid is arranged relative to the operating member, rotates relative to the driven-side rotation member and movable in a direction along the rotation axis; a restraining structure structured by the operating member and the intermediate member, the restraining structure including a primary through-hole extending through the operating member and provided on a surface of the operating member where the electromagnetic solenoid makes contact and a secondary through-hole extending through the intermediate member and provided on a surface of the intermediate member where a magnetic flux from the operating member acts on; and wherein the restraining structure is provided with the primary through-hole and the secondary through-hole arranged in a positional relationship configured to allow a rotation of the driving member by inertia after the operating member is attracted to contact the electromagnetic solenoid by activating the electromagnetic solenoid, to increase an attraction force that acts on the intermediate member at a time at which the operating member and the intermediate member reach a rotational phase that cancels the wrap spring from the pressure bonding state with the driving-side rotation member, and to restrain the rotation of the driving member by attracting the intermediate member to contact the operating member by the attraction force that acts on the intermediate member.