Linear Actuator

Abstract

A linear actuator has an alternating drive apparatus, an alternating motion member, a fixing member fixed to a housing member, a direct acting member, a first wedge joining mechanism incorporated between the alternating motion member and the direct acting member, and a second wedge joining mechanism incorporated between the fixing member and the direct acting member. The first wedge joining mechanism and the second wedge joining mechanism have an inclined surface, a non-inclined surface at a constant distance from the central axis, and a wedge member arranged between the inclined surface and the non-inclined surface. The non-inclined surfaces of the first and second wedge joining mechanisms are formed on the direct acting member. The inclined surface of the first wedge joining mechanism is formed on the alternating motion member, and the inclined surface of the second wedge joining mechanism is formed to the fixing member.

1 . A linear actuator comprising:
 first and second joint members, a housing member for storing the first and second joint members, a drive apparatus for driving the first and second joint members in a mutually approaching direction thereof and in a separating direction thereof in the housing member, a direct acting member joined to the first and second joint members for executing a linear motion in an axial direction,   a first wedge joining mechanism incorporated between the first joint member and the direct acting member for permitting a relative displacement in one axial direction between the first joint member and the direct acting member and inhibiting a relative displacement in the other axial direction between the first joint member and the direct acting member, and a second wedge joining mechanism incorporated between the second joint member and the direct acting member for permitting a relative displacement in one axial direction between the second joint member and the direct acting member and inhibiting a relative displacement in the other axial direction between the second joint member and the direct acting member, wherein:   the first wedge joining mechanism and the second wedge joining mechanism include an inclined surface at a distance from a central axis changing in the axial direction, a non-inclined surface at a constant distance from the central axis, and a wedge member arranged between them, and   the direct acting member is supported in a radial direction by a shaft support section provided in the housing member.   
     
     
         2 . The linear actuator according to  claim 1 , wherein the first and second joint members are restricted on a radial position by the direct acting member. 
     
     
         3 . The linear actuator according to  claim 1 , further comprising a wedge joint inhibition mechanism for inhibiting wedge joining by the wedge member. 
     
     
         4 . The linear actuator according to  claim 1 , wherein the drive apparatus includes a pair of movable iron cores sliding in the axial direction, a spring arranged between the movable iron cores for driving the movable iron cores in a direction for separating them from each other, and a magnetic coil for driving the movable iron cores in a direction for bringing the movable iron cores close to each other, wherein the magnetic coil is supplied with power to generate drive force for extending and contracting the paired movable iron cores in the axial direction. 
     
     
         5 . The linear actuator according to  claim 1 , wherein the first and second joint members make contact respectively with two surfaces of the drive apparatus orthogonal to the axial direction and springs are arranged additionally outside the first and second joint members and are held by the housing member in the axial direction. 
     
     
         6 . The linear actuator according to  claim 1 , wherein the first and second joint members are arranged on an outer peripheral part of the direct acting member. 
     
     
         7 . The linear actuator according to  claim 1 , wherein at least one of the first and second wedge joining mechanisms has a plurality of wedge members arranged in a circumferential direction and the inclined surfaces in contact with the wedge members are formed by a common inner peripheral spherical surface. 
     
     
         8 . The linear actuator according to  claim 7 , wherein a forward inclined surface and a backward inclined surface of at least one of the first and the second wedge joining mechanisms are formed by a common inner peripheral spherical surface. 
     
     
         9 . The linear actuator according to  claim 7 , wherein the wedge member in contact with the inclined surface formed by a part of the inner peripheral spherical surface is a rotator having a contour shape composed of a part of a great circle of the spherical surface and the non-inclined surface of the direct acting member in contact with the wedge member is a concave groove having a contour of a right-angled section thereof composed of a part of the great circle. 
     
     
         10 . The linear actuator according to  claim 8 , wherein the wedge member in contact with the inclined surface formed by a part of the inner peripheral spherical surface is a rotator having a contour shape composed of a part of a great circle of the spherical surface and the non-inclined surface of the direct acting member in contact with the wedge member is a concave groove having a contour of a right-angled section thereof composed of a part of the great circle.