| 摘要 |
Provided is a linear actuator which is simple in structure, inexpensive to manufacture, in addition, has small magnetic leakage, and can provide a large inertial force without increasing the number of parts and weight. The linear actuator is provided with an output shaft 12 which is supported on a supporting case 11 so as to linearly reciprocate freely, an elastic member 13 which biases the output shaft 12 toward a middle position of the linear reciprocation thereof, a permanent magnet 14 which is fixed to the output shaft 12, a coil 15 which linearly reciprocates the output shaft 12 by having a variable magnetic field act on the permanent magnet 14 and is fixed to the supporting case 11 such that the coil 15 faces one of magnetic poles of the permanent magnet 14, a yoke 16, which is composed of a magnetic material, has a midway portion tightly secured to the other magnetic pole of the permanent magnet 14, extends to the exterior of the coil 15 along the exterior of the permanent magnet 14 with a space from the permanent magnet 14, and has an end portion disposed close to the exterior of the coil 15, and power supply means for forming a variable magnetic field on the coil 15. |
| 主权项 |
1. A linear actuator comprising:
a supporting case, two magnetic units disposed in series inside the supporting case such that the magnetic units face each other so as to be vertically symmetric wherein the magnetic unit is composed of a coil, a permanent magnet, a yoke, and a pole piece, an output shaft which extends upward through the supporting case and a lower end portion of which is secured to a top wall portion of the upper yoke, elastic members which bias the output shaft toward an middle position of linear reciprocation of the output shaft, a supporting member which immovably supports two coils in a midway portion of the supporting case in a height direction, a connecting member which integrally connects an upper moving member composed of the permanent magnet, the yoke, and the pole piece in the magnetic unit with a lower moving member composed of the permanent magnet, the yoke, and the pole piece in the magnetic unit, and a power supply means for forming variable magnetic fields in the coils, wherein the two moving members connected by the connecting member are provided so as to linearly reciprocate freely in an up and down direction against the supporting case, each of the upper yoke and the lower yoke is composed of a bottomed cylindrical magnetic material, an opening of the upper yoke faces downward, an opening of the lower yoke faces upward, and both yokes are arranged in an opposing relationship with respect to each other across the supporting member, and one magnetic pole of the permanent magnet is secured to the pole piece, another magnetic pole of the permanent magnet is secured to an inner bottom portion of the yoke, the coil is disposed between the end portion of the circumferential wall portion of the yoke and the facing pole piece with a tiny gap, thereby to form a magnetic circuit by the permanent magnet, the pole piece, the yoke, and the coil in the upper and lower magnetic units. |
