JP2009075085A5 - - Google Patents

Claims (13)

An electric motor that reciprocally rotates the drive shaft ;
A ball screw,
A semi-rigid coupling that coaxially connects the ball screw and the drive shaft of the electric motor;
A nut that engages with the ball screw;
A linear guide that restricts the moving direction of the nut to only the axial direction of the ball screw;
A linear motion actuator comprising: a support plate having the electric motor fixed to one surface and the linear guide fixed to the other surface ;
The support plate is provided with an opening through which the ball screw is vertically inserted, and a bearing for rotatably supporting the ball screw is fixed to the opening.
The semi-rigid coupling is
A pair of outer rings that are rigid elements having a tapered hole formed in the center;
A cylindrical through-hole is formed between the pair of outer rings and passes through a shaft connected to the center, and can be engaged with the inner circumferences of the tapered holes of the pair of outer rings at both axial ends of the outer circumference. An inner ring which is an elastic element or viscoelastic element formed with a tapered surface;
With
The ball screw and the drive shaft of the electric motor are inserted into the through hole of the inner ring, the inner circumferences of the tapered holes of the pair of outer rings are in contact with the tapered surfaces of the inner ring, and the pair of outer rings are fixed to each other with bolts. Thus , the linear actuator is characterized in that the front end of the drive shaft of the electric motor and the front end of the shaft portion of the ball screw are connected to each other with an interval through the inner ring . The semi-rigid coupling provides torsional rigidity equal to or greater than that of the ball screw and the drive shaft of the electric motor to the connection between the ball screw and the drive shaft of the electric motor, and provides flexibility in the bending direction, and The linear motion actuator according to claim 1, wherein the linear motion actuator is configured to inhibit transmission of vibration in an extension direction of the drive shaft of the electric motor. The inner ring of the semi-rigid coupling is a viscoelastic element, linear actuator according to claim 1 or 2, characterized in that. Linear actuator according to claim 3, wherein at least a portion is formed of a resin, of the viscoelastic element. The semi-rigid coupling, the linear actuator according to any one of claims 1 to 4, wherein the attenuation factor of the vibration is configured to maximize, that at a desired frequency. The linear motion actuator according to claim 5 , wherein the desired frequency is a drive frequency of the motor. The linear motion actuator according to claim 5, wherein the desired frequency is a natural frequency of a drive shaft of the motor. The linear motion actuator according to any one of claims 1 to 7, wherein the electric motor is a low-inertia servo motor that can be driven reversely at a repetition rate of 500 Hz.   The linear actuator according to claim 8, wherein the linear actuator can generate a linear reciprocating motion at a repetition rate of 500 Hz. Linear actuator according to any one of claims 1 to 9, wherein the bearing is an angular contact ball bearing, characterized in that. The angular contact ball bearing, claim 10 load-bearing direction of the axial load is a combination angular ball bearing comprising a pair of single row angular contact ball bearing which is arranged such that the opposite directions, characterized in that Linear actuator. Linear actuator of claim 11 wherein the combined angular ball bearings to a front combination type duplex angular contact ball bearings, characterized in that. The linear motion actuator according to any one of claims 1 to 12 , wherein the support plate is composed of one metal plate or a plurality of metal plates integrated by welding.