Abstract: The method for manufacturing the worm wheel includes a step of combining the first molds for molding the first tooth surfaces of the wheel teeth to be pushed by the shaft tooth when the worm shaft rotates in the direction and the second molds for molding the second tooth surfaces of the wheel teeth to be pushed by the shaft tooth when the worm shaft rotates in the direction to form the cavities defined by the first molds and the second molds, a step of injecting the molten resin into the cavities to mold the wheel teeth, and a step of separating the first molds and the second molds from each other in the direction oblique to the tooth traces of the wheel teeth.

Abstract: An electric power steering device includes a worm shaft; a bearing rotatably supporting the worm shaft; a coil spring configured to bias the worm shaft toward the worm wheel via the bearing; a gear case including an insertion hole, the coil spring being insertable into the insertion hole; and plug configured to close the insertion hole. The plug includes a body part and a supporting part configured to support the coil spring. An outer peripheral surface of the plug is formed into a curved surface from the body part to the supporting part.

Abstract: A power steering device includes a worm shaft configured to rotate as an electric motor is driven; a worm wheel meshed with the worm shaft, the worm wheel being configured to transmit a rotational force of the electric motor to a rack shaft configured to turn wheels; a bearing that rotatably supports a tip side of the worm shaft; a gear case that houses the worm shaft; a biasing member configured to bias the worm shaft toward the worm wheel via the bearing; and a holder including a housing hole configured to house the bearing movably in a biasing direction of the biasing member. The holder includes a plurality of bulging parts formed to bulge radially outwardly, the bulging parts being configured to come into contact with an inner peripheral surface of the gear case.

Abstract: A power steering device includes a worm shaft configured to rotate as an electric motor is driven; a worm wheel meshed with the worm shaft, the worm wheel being configured to transmit a rotational force of the electric motor to a rack shaft configured to turn wheels; a bearing that rotatably supports a tip side of the worm shaft; a gear case that houses the worm shaft; a biasing member configured to bias the worm shaft toward the worm wheel via the bearing; and a holder including a housing hole configured to house the bearing movably in a biasing direction of the biasing member. The holder includes a plurality of bulging parts formed to bulge radially outwardly, the bulging parts being configured to come into contact with an inner peripheral surface of the gear case.

Abstract: A shaft coupler that couples a worm shaft and an output shaft of an electric motor in an electric power steering device includes a joint on a motor side that is connected to the output shaft, a joint on a worm side that is connected to the worm shaft, and a coupling that is provided between the joints and that is for transmitting rotational torque of the electric motor to the worm shaft. The joint on the motor side and the joint on the worm side, each having a plurality of protrusion parts that extend in an axial direction, are arranged so that the protrusion parts are aligned alternately in a circumferential direction. The coupling is formed by a plurality of caps that are fitted to the protrusion parts of the joint on the motor side or the joint on the worm side.

Abstract: A power steering device for assisting a steering force applied to a steering wheel by a driver includes a worm shaft that rotates in association with driving of an electric motor, a worm wheel that meshes with the worm shaft and transmits a rotational force of the electric motor to a rack shaft steering a wheel, a bearing that supports a tip end side of the worm shaft, a gear case that houses the worm shaft, a lid that closes an opening formed in a tip end portion of the gear case, a first elastic portion arranged in a compressed manner between the gear case and the lid, and a second elastic portion arranged between an inner circumferential surface of the gear case and an outer circumferential surface of the bearing. The first and the second elastic portion are formed in an integrated manner via a small thickness portion.

Abstract: A power steering device for assisting a steering force applied to a steering wheel by a driver includes a worm shaft that rotates in association with driving of an electric motor, a worm wheel that meshes with the worm shaft and transmits a rotational force of the electric motor to a rack shaft steering a wheel, a bearing that supports a tip end side of the worm shaft, a gear case that houses the worm shaft, a lid that closes an opening formed in a tip end portion of the gear case, a first elastic portion arranged in a compressed manner between the gear case and the lid, and a second elastic portion arranged between an inner circumferential surface of the gear case and an outer circumferential surface of the bearing. The first and the second elastic portion are formed in an integrated manner via a small thickness portion.

Abstract: A power steering device includes a first bearing and a second bearing that rotatably support the base-end side and the tip-end side of a worm shaft, a biasing member that biases the outer circumferential surface of the second bearing, and an elastic member that is arranged between the inner circumferential surface of a gear case and the outer circumferential surface of the second bearing. The inner circumferential surface of the gear case is formed such that the second bearing can move towards a worm wheel by the biasing force of the biasing member, the inner circumferential surface of the gear case is provided with a ring-like groove that houses the elastic member, and the center of the ring-like groove is offset towards the worm wheel side from the center axis of the worm shaft when the first bearing and the second bearing are in a coaxial state.

Abstract: A shaft coupler that couples a worm shaft and an output shaft of an electric motor in an electric power steering device includes a joint on a motor side that is connected to the output shaft, a joint on a worm side that is connected to the worm shaft, and a coupling that is provided between the joints and that is for transmitting rotational torque of the electric motor to the worm shaft. The joint on the motor side and the joint on the worm side, each having a plurality of protrusion parts that extend in an axial direction, are arranged so that the protrusion parts are aligned alternately in a circumferential direction. The coupling is formed by a plurality of caps that are fitted to the protrusion parts of the joint on the motor side or the joint on the worm side.

Abstract: A power steering device includes a first bearing and a second bearing that rotatably support the base-end side and the tip-end side of a worm shaft, a biasing member that biases the outer circumferential surface of the second bearing, and an elastic member that is arranged between the inner circumferential surface of a gear case and the outer circumferential surface of the second bearing. The inner circumferential surface of the gear case is formed such that the second bearing can move towards a worm wheel by the biasing force of the biasing member, the inner circumferential surface of the gear case is provided with a ring-like groove that houses the elastic member, and the center of the ring-like groove is offset towards the worm wheel side from the center axis of the worm shaft when the first bearing and the second bearing are in a coaxial state.