Electromagnetic actuator
An electromagnetic actuator includes a stator, a coil for excitation, a mover, a shaft of a single outer diameter, and a buffer unit. The mover moves in a predetermined axis direction to move to an actuation position due to energization of the coil and return to a rest position due to non-energization of the coil. The shaft is fixed to the mover and exerts a driving force to outside. The buffer unit is held at the mover and positions the mover at the rest position while absorbing impact when the mover returns to the rest position. The buffer unit includes: a rod abutting against the stator at the rest position; a biasing member biasing the rod toward the stator; and a buffer member interposed between the rod and the shaft. The mover includes a fitting hole into which the shaft is fitted and a receiving part receiving the biasing member.
1 . An electromagnetic actuator comprising:
a stator;
a coil for excitation;
a mover which moves in a predetermined axial direction to move to an actuation position due to energization of the coil and return to a rest position due to non-energization of the coil;
a shaft of a single outer diameter which is fixed to the mover and exerts a driving force to outside; and
a buffer unit which is held at the mover and positions the mover at the rest position while absorbing impact when the mover returns to the rest position, wherein
the buffer unit comprises: a rod which abuts against the stator at the rest position; a biasing member which biases the rod toward the stator; and a buffer member which is interposed between the rod and the shaft, and
the mover comprises a restricting part, a fitting hole, a guide inner wall surface and a receiving part,
the restricting part is crimped to restrict the rod from coming off,
the shaft is fitted into the fitting hole,
wherein the guide inner wall surface guides the rod slidably in the axial direction, and the guide inner wall surface is formed to have a diameter larger than a diameter of the fitting hole,
wherein the receiving part is formed in an annular shape around the fitting hole and receives one end part of the biasing member in the axial direction, and the receiving part is formed to have an outer diameter larger than a diameter of the fitting hole.
2 . The electromagnetic actuator according to claim 1 , wherein
the biasing member is a compression-type coil spring.
3 . The electromagnetic actuator according to claim 2 , wherein
the mover comprises a fitting inner wall surface which is formed continuously with an outer edge of the receiving part and into which one end part of the coil spring is fitted.
4 . The electromagnetic actuator according to claim 2 , wherein
the shaft is press-fitted into the fitting hole such that a fixed end part of the shaft protrudes inward from the receiving part in the axial direction.
5 . The electromagnetic actuator according to claim 1 , wherein
the mover is a forged product.
6 . The electromagnetic actuator according to claim 1 , wherein
the stator comprises:
a first stator which comprises a rest-side stopper part abutting against the rod and accommodates the mover; and
a second stator comprising a through-hole which allows the shaft to pass and exposes a free end part of the shaft.
7 . The electromagnetic actuator according to claim 6 , wherein
the first stator comprises: a cylindrical part which accommodates the mover in a non-contact manner; a bottom wall part which is continuous with the cylindrical part to define the rest-side stopper part; and a flange part which extends in a radial direction from the cylindrical part, and
the second stator comprises: an inner cylindrical part which defines the through-hole; and an outer cylindrical part which surrounds the coil arranged around the cylindrical part and the inner cylindrical part and fixes the flange part by crimping.
8 . The electromagnetic actuator according to claim 7 , wherein
the second stator comprises an actuation-side stopper part which receives the mover at the actuation position.
9 . The electromagnetic actuator according to claim 8 , wherein
the actuation-side stopper part is subjected to a hardening treatment.
10 . The electromagnetic actuator according to claim 8 , wherein
the actuation-side stopper part comprises a guide hole which slidably guides the shaft.
11 . The electromagnetic actuator according to claim 10 , wherein
the second stator comprises a bearing which is fitted to the through-hole to slidably guide the shaft.