Armrest

Abstract

An armrest attachable to a seat back includes: an arm frame; and a clutch through which the arm frame is rotatably supported by the seat back. The clutch includes: an inner member (inner race) configured to be fixed to one of the arm frame and the seat back; an outer race provided radially outward of the inner member and spaced apart from the inner member, and configured to be fixed to the other one of the arm frame and the seat back; an unlocking member provided coaxially with the inner member and the outer race and configured to be rotatable relative to both of the inner member and the outer race; and an unlocking manipulation mechanism configured to actuate the unlocking member to unlock a locked state.

1 . An armrest attachable to a seat back, comprising:
 an arm frame; and   a clutch through which the arm frame is rotatably supported by the seat back,   wherein the clutch comprises:   an inner member configured to be fixed to one of the arm frame and the seat back;   an outer race provided radially outward of the inner member and spaced apart from the inner member, and configured to be fixed to the other one of the arm frame and the seat back;   an unlocking member provided coaxially with the inner member and the outer race, and configured to be rotatable relative to both of the inner member and the outer race; and   an unlocking manipulation mechanism configured to actuate the unlocking member to unlock a locked state.   
     
     
         2 . The armrest according to  claim 1 , wherein the inner member is an inner race, wherein the armrest comprises a movable piece received in a pocket which is located between the inner race and the outer race and includes a portion whose radial width decreases with distance toward one circumferential direction, wherein the unlocking member has an unlocking piece arranged adjacent to one side of the movable piece in the one circumferential direction, and wherein the unlocking manipulation mechanism is configured to actuate the unlocking member to unlock the locked state in which the movable piece is trapped by inner walls of the pocket. 
     
     
         3 . The armrest according to  claim 2 , wherein the clutch is a one-way clutch, and the unlocking manipulation mechanism includes a first manipulation member configured to be engaged with or fixed to the unlocking member, and a switching member configured to be coaxial with and rotatable relative to both of the inner race and the outer race and having a circumferential surface, wherein the first manipulation member contacts the circumferential surface of the switching member, and the circumferential surface of the switching member includes a small diameter portion and a large diameter portion having a diameter greater than that of the small diameter portion, wherein one of the inner race and the outer race has a rotation restricting portion engageable with the switching member to restrict a relative rotation thereof with respect to the switching member in a predetermined angular range, wherein the circumferential surface is provided with a return engagement portion protruding radially from the circumferential surface, and wherein when the first manipulation member is brought into contact with one of the small diameter portion and the large diameter portion, the unlocking member is allowed to rotate in the one circumferential direction to cause the movable piece to be trapped and thus locked by the inner walls of the pocket, whereas when the first manipulation member is brought into contact with the other one of the small diameter portion and the large diameter portion, the unlocking member is allowed to rotate in the other circumferential direction to unlock the locked state of the movable piece. 
     
     
         4 . The armrest according to  claim 2 , wherein the inner race comprises a first metal part constituting a part of the inner walls of the pocket, and a first resin part, and wherein a rugged portion formed on an inner periphery of the first metal part and a rugged portion formed on an outer periphery of the first resin part are engaged with each other such that the first metal part and the first resin part are assembled together to prevent relative slippage in circumferential directions. 
     
     
         5 . The armrest according to  claim 2 , further comprising an urging member arranged to urge the movable piece toward the one circumferential direction, wherein the inner race comprises a first metal part constituting a part of the inner walls of the pocket, and a first resin part, wherein a rugged portion formed on an inner periphery of the first metal part and a rugged portion formed on an outer periphery of the first resin part are engaged with each other such that the first metal part and the first resin part are assembled together to prevent relative slippage in circumferential directions, wherein at the outer periphery of the first metal part, the first metal part has an urging member receiving recess which is recessed toward a center of the first metal part to receive the urging member, and wherein the rugged portion of the first metal part has a protrusive portion protruding toward the center of the first metal part, and the protrusive portion is arranged radially inward of the urging member receiving recess. 
     
     
         6 . The armrest according to  claim 2 , wherein the outer race comprises a second metal part constituting a part of the inner walls of the pocket, and a second resin part, and wherein a rugged portion formed on an outer periphery of the second metal part and a rugged portion formed on an inner periphery of the second resin part are engaged with each other such that the second metal part and the second resin part are assembled together to prevent relative slippage in circumferential directions. 
     
     
         7 . The armrest according to  claim 6 , wherein the rugged portion of the second metal part has a protrusive portion protruding radially outward, and when the clutch is in the locked state, the protrusive portion is positioned radially outward of the movable piece. 
     
     
         8 . The armrest according to  claim 2 , wherein the unlocking member has an extension portion extending radially outward, and wherein the first manipulation member engages with the unlocking member at the extension portion, and the first manipulation member is arranged radially outward of the outer race in a region where the first manipulation member and the outer race overlap in an axial direction. 
     
     
         9 . The armrest according to  claim 2 , wherein the inner walls of the pocket have a projection at one side of the movable piece in the one circumferential direction, and when the inner race and the outer race are forcibly and relatively rotated in a locking direction, the projection contacts the movable piece. 
     
     
         10 . The armrest according to  claim 2 , wherein the unlocking manipulation mechanism is engaged with or fixed to the unlocking member and includes a second manipulation member extending toward a distal end of the arm frame, and wherein when the second manipulation member is manipulated to rotate the unlocking member in the other circumferential direction, the movable piece is allowed to be unlocked. 
     
     
         11 . The armrest according to  claim 3 , wherein the unlocking manipulation mechanism is engaged with or fixed to the unlocking member and includes a second manipulation member extending toward a distal end of the arm frame, wherein when the second manipulation member is manipulated to rotate the unlocking member in the other circumferential direction, the movable piece is allowed to be unlocked, wherein the first manipulation member is provided arcuately around an axis of rotation of the arm frame, and the second manipulation member is provided along a longitudinal direction of the arm frame, and wherein the first manipulation member and the second manipulation member are arranged so as not to overlap each other as viewed from an axial direction. 
     
     
         12 . The armrest according to  claim 3 , wherein the small diameter portion and the large diameter portion are formed as flanges extending from a peripheral edge of the switching member in an axial direction of the switching member. 
     
     
         13 . The armrest according to  claim 12 , wherein the flange constituting the small diameter portion and the flange constituting the large diameter portion are connected to each other. 
     
     
         14 . The armrest according to  claim 3 , wherein the return engagement portion is integrally molded with the switching member. 
     
     
         15 . The armrest according to  claim 8 , wherein the extension portion is integrally molded with the unlocking member. 
     
     
         16 . The armrest according to  claim 8 , wherein a first attachment member is fixed to the inner race and a second attachment member is fixed to the outer race, wherein one of the first attachment member and the second attachment member has a stopper which protrudes toward the one-way clutch and is engageable with the inner race or the outer race fixed to the other one of the first attachment member and the second attachment member to restrict a rotation range of the one of the first attachment member and the second attachment member, and wherein the stopper is arranged in a region where the stopper and the extension portion overlap in the axial direction and where the stopper and the extension portion do not overlap as viewed from the axial direction.