Patent ID: 7857278

Claim:
A vehicular mirror device comprising: a mirror stand on which a support shaft is provided and which is coupled to a vehicle body; a rotary case that is disposed on an outer periphery of the support shaft such that the rotary case is supported rotatably by the support shaft, and that is coupled with a rearview mirror; a driven clutch disk of annular shape, that is fitted by insertion to the outer periphery of the support shaft such that the driven clutch disk is fixed to the support shaft along a rotation direction whose center is the support shaft, and is supported movably in an axial direction of the support shaft; a driving clutch disk of annular shape, that is fitted by insertion to the outer periphery of the support shaft such that the driving clutch disk is supported relatively rotatably by the support shaft, and is coupled to the rotary case along the rotation direction; a clutch biasing member that biases in the axial direction the driven clutch disk toward the driving clutch disk; a clutch groove that is formed on one of one end surface of the driven clutch disk or another end surface of the driving clutch disk, the clutch groove being formed so as to extend along a radial direction whose center is an axis center of the support shaft; and a clutch projection that is formed on the other of the one end surface of the driven clutch disk or the another end surface of the driving clutch disk, the clutch projection being formed so as to extend along the radial direction, in which when torque is transmitted from the rotary case to the driving clutch disk in a value which is equal to or smaller than a set value corresponding to a bias force of the biasing member, the clutch projection is received in the clutch groove to be in a coupling state in which the driving clutch disk is coupled to the driven clutch disk so as to allow transmission of torque, and when torque is transmitted from the rotary case to the driving clutch disk in a value which exceeds the set value, the clutch projection is moved out from the clutch groove to release the coupling state; wherein the clutch groove is formed substantially in a trapezoidal shape in a cross section along a circumferential direction whose center is the axis center of the support shaft, in which a width of the clutch groove increases from a groove bottom surface toward a groove opening end, and the clutch projection is formed substantially in a trapezoidal shape in the cross section along the circumferential direction, in which a width of the clutch projection decreases from a projection base end toward a projection tip end, and a top surface of the clutch projection is formed in an inverted radial shape in which a width of the top surface decreases from an inner periphery side toward an outer periphery side.