JP2801159B2 - Linear actuator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator, and more particularly, to a linear actuator in which a slide rod is provided in a housing and the slide rod performs a linear motion. In the above, the brake shoe driving member is smoothly displaced under the rolling operation of the rolling member interposed between the housing and the slide rod, whereby the brake shoe is securely biased or deenergized, and The rod can be braked reliably,
The present invention relates to a linear actuator capable of reliably releasing braking of the slide rod. 2. Description of the Related Art In recent years, with the technical development of automatic machines represented by robots, the importance of linear actuators for performing accurate linear motion has been increasingly recognized and revealed. In particular, linear actuators for transferring workpieces of assembly robots that require high positioning accuracy are being widely used. [0003] As described above, these linear actuators are not only accurate in positional accuracy, but also reliable, have a long life, are compact, have a uniform operating force, can easily change the moving direction, and have high bending rigidity. Etc. are required. [0004] To meet these requirements, various linear actuators have been conventionally proposed. An example is an apparatus disclosed in Japanese Patent Publication No. 56-14883. In this prior art linear actuator,
A linear ball bearing is disposed in the longitudinal direction of the inner circumference of the housing, and a slide rod in which a cylinder is incorporated in contact with the bearing is disposed, and the slide rod is slid in the axial direction. Are provided with a plurality of orifices, and an operating force is applied to the slide rod by hydraulic pressure or pneumatic pressure or the like to achieve positional accuracy and smooth sliding. [0005] However, the linear ball bearing provided in the linear actuator according to the prior art has a function of smoothly sliding the slide rod along the axial direction. It does not exhibit the function of braking the slide rod. In addition, since the linear actuator requires a control device such as a hydraulic pressure or a pneumatic pressure, the size of the entire device is increased. Further, since the control device such as a hydraulic pressure or a pneumatic pressure is expensive, there is a problem in economical efficiency. There are various inconveniences. Further, since the linear actuator maintains the positional accuracy by the operating force related to the hydraulic pressure or the air pressure, the slide rod cannot be braked when the power supply of the control device related to the hydraulic pressure or the air pressure is cut off. And, in particular,
Various difficulties have been pointed out, for example, it is difficult to ensure safety at the moment of a power interruption, and there is a possibility that a malfunction may occur. SUMMARY OF THE INVENTION The present invention has been made to overcome all of the above-mentioned disadvantages, and a slide rod can be braked reliably by smoothly displacing a brake shoe driving member via a rolling member. It is another object of the present invention to provide a linear actuator capable of reliably releasing the braking of the slide rod. [0009] In order to achieve the above object, the present invention provides a housing, in which a plurality of coil units and a magnetic body as an iron core are provided, and the coil unit and the magnetic body are provided. A linear actuator having a slide rod that penetrates the slide rod and is relatively displaceable with respect to the housing, a brake shoe that presses the slide rod to brake the slide rod, the slide rod and the housing, When a brake shoe driving member made of a magnetic material disposed between the housing and the brake shoe driving member is interposed between the brake shoe and the brake rod, or when releasing the brake of the slide rod, A plurality of rolling members for guiding the brake shoe driving member substantially parallel to the axis of the slide rod by rolling; And the following. According to the linear actuator of the present invention,
The brake shoe is urged by the displacement action of the brake shoe driving member, and the brake shoe presses the slide rod to brake the slide rod. In this case, since the brake shoe driving member is guided by the plurality of rolling members, it is smoothly displaced along the axial direction of the slide rod. As a result, the brake shoe can be reliably biased. Next, a preferred embodiment of a linear actuator according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view of a linear actuator having one slide rod according to an embodiment of the present invention. That is, in FIG. 1, reference numeral 10 indicates a linear actuator, and the linear actuator 1
0 basically comprises a rectangular parallelepiped housing 12 and a conductor such as aluminum or copper.
And a slide rod 14 that is provided so as to be relatively displaceable with respect to the slide rod 2. In the housing 12, contacts 16a to 16c for inputting electric signals are connected to a terminal block 18.
Mounted on top. FIG. 2 is a partially omitted sectional view of the linear actuator 10. As shown in FIG. In FIG. 2, a cylindrical iron core 24 made of a magnetic material is disposed on the inner peripheral surface of the housing 12, and a donut-shaped coil is formed on the inner peripheral surface of the iron core 24 through an annular recess. (Coil unit) 26a to 26f (however, 2
6c to 26f are not shown). The iron core 24
And the coils 26a to 26f are housed in the housing 12, respectively. A rectangular cap member 28c is engaged with both ends of the housing 12, and a slide rod 14 is inserted into a hole defined in the cap member 28c.
Here, a linear ball bearing (not shown) may be provided in the hole of the cap member 28c in which the slide rod 14 fits, if necessary. Although not shown, the donut-shaped coils 26a to 26f are connected to a predetermined connection mode described later,
a to 16c. A moving member (brake shoe driving member) 52 made of a magnetic material is provided at an end of the housing 12.
The moving member 52 is formed such that the bear coil 50 is embedded and the spring 22 makes contact with the iron core 24. The moving member 52 is formed in a ring shape having a hole having a tapered cross section on the inner wall surface, and is provided movably along the axial direction of the slide rod 14 via ball bearings 58a and 58b. An annular projection 28d is formed on one side surface of the cap member 28c,
Between the tapered surface of the moving member 52 and the projection 28d of the cap member 28c, the tapered surface and the projection 28 are provided.
Roller members 54 that engage with the respective members d and press the brake shoes 56 against the slide rod 14 are provided.
In this case, the displacement of the roller member 54 is regulated by engaging with the protrusion 28d. The linear actuator 10 according to the present invention is basically constructed as described above, and its operation and effects will be described below. As can be easily understood from FIGS. 1 and 2, in the linear actuator 10 according to the present invention,
The slide rod 14 and the housing 12 are mutually slidable. That is, in the present invention, whether to fix the housing 12 or the slide rod 14 can be appropriately selected according to the needs of the user. In this case, the other component is replaced with the moving component with respect to the fixed component. It is possible to use as. Here, for convenience of explanation, it is assumed that the housing 12 is fixed to a fixed body (not shown). Therefore, the donut type coils 26a to 26a
When the power is not supplied to the motor f, the moving member 52 is moved by the ball bearings 58a, 58b due to the elastic force of the spring 22.
And moves in the direction of arrow A while slidingly contacting the ball bearings 58a and 58b. A roller member 5 slidably disposed on the brake shoe 56.
When the roller 4 comes into contact with the projection 28d of the cap member 28c and stops, the roller member 54 engaging with the tapered surface of the moving member 52 receives a normal force from the moving member 52 on the slide rod 14. The brake shoe 56 presses the slide rod 14 by the force in the normal direction. As a result, the slide rod 14 is braked by the frictional force.
As described above, when the slide rod 14 is braked, the moving member 52 is guided substantially in parallel with the axis of the slide rod 14 under the rolling operation of the plurality of ball bearings 58a and 58b, so that the moving member 52 is moved by an arrow. The slide rod 14 can be securely displaced along the direction A, and the slide rod 14 can be reliably braked. On the other hand, donut type coils 26a to 26f
When power is supplied to the movable member 52, the moving member 52 receives a force attracted to the iron core 24, and at this time, the slide rod 14 becomes slidable. That is, the donut-shaped coils 26a to 26a
At the time of energizing the 6f, the moving member 52 moves in a direction parallel to the axis of the slide rod 14 against the elastic force of the spring 22 due to the suction force generated in the iron core 24, and the roller member 54 By moving the roller member 54 away from the projection 28d of the cap member 28c by moving the roller member inward, braking of the slide rod 14 is released. When the braking of the slide rod 14 is released, the moving member 52 is guided substantially parallel to the axis of the slide rod 14 under the rolling operation of the plurality of ball bearings 58a, 58b, so that the moving member 52 is moved by an arrow. The slide rod 14 can be securely displaced in the direction opposite to the direction A, and the braking of the slide rod 14 can be reliably released. In this state where the braking on the slide rod 14 is released, the slide rod 14 can be moved right and left by applying an electromagnetic force to the slide rod 14. These are donut-shaped coils 26a to 26
This is possible by passing an appropriate alternating current through f. Therefore, next, the donut-shaped coil 26a
Consider the direction of action of the electromagnetic force induced by passing an appropriate alternating current through to 26f. In the circuit diagram of FIG.
Numerals 0a to 40l denote fuses that melt at a predetermined temperature and protect the linear actuator 10 from burning of the coil. However, these fuses are not the gist of the present invention and will not be described in detail. Here, in order to facilitate understanding of the above connection, the circuit connection diagram is rearranged and arranged as shown in FIG. 3B.
As can be easily understood from the circuit connection diagram of FIG.
This circuit is a circuit equivalent to a Δ-connection load in three-phase alternating current. Therefore, as shown in FIG.
6c is connected to a symmetric three-phase AC power supply 36. Here, the reference symbol E represents the ground of the symmetric three-phase AC power supply 36. Next, the direction of the magnetic flux interlinking with the slide rod 14 when the current from the symmetrical three-phase AC power supply 36 is supplied to the donut-shaped coils 26a to 26f, similarly to the first slide rod 14. The direction of the generated eddy current and the electromagnetic force generated by these magnetic flux and eddy current, so-called,
The direction of the Lorentz force will be described. In the symmetric three-phase alternating current, if the period of the power of one arbitrary phase is T, the electromotive forces of the other phases have the same waveform and have a T
The same process is repeated with a delay of / 3, 2T / 3. Therefore, now, assuming that T = 3t ₁ , time t ₁ , 2t ₁ ,
If Shimese a magnetic field orientation caused by toroidal coil 26a-26f in time 3t ₁ macroscopically, represented by the direction of magnetic field lines drawn upwardly in FIG. 3a. In the direction diagram of the magnetic field drawn above this FIG. 3 a, the symbol S represents the south pole of the magnet and the symbol N represents the north pole of the magnet. The arrow drawn between the S pole and the N pole indicates the direction of the line of magnetic force. As can be easily understood from the diagram showing the direction of the magnetic field lines drawn in the upper part of FIG. 3A, the magnetic field moves along the axial direction of the slide rod 14, so that the eddy current is generated by 14 occurs in a substantially spiral shape. In this case, the slide rod 14 receives an electromagnetic force in the axial direction, and as a result, performs a linear motion in the axial direction. In addition, the moving direction, moving speed,
The moving distance and the like can be easily controlled by preparing a three-phase power supply reversing switch and a power supply device with variable voltage and frequency. As described above, according to the present invention, when braking the slide rod or releasing the braking of the slide rod, a plurality of rolling members roll to thereby drive the brake shoe. The member can be smoothly guided substantially parallel to the axis of the slide rod. As a result, the brake shoe is reliably biased or de-energized, and the slide rod can be braked reliably, and the brake of the slide rod can be reliably released. Also, the brake shoe urged by the brake shoe driving member for the rolling operation of the rolling member enables immediate braking even when the power supply is momentarily interrupted, thereby improving safety and preventing malfunction. To play. Further, since the slide rod can be moved by the electromagnetic force, the contact portion between the slide rod and the inner periphery of the housing can be considerably reduced.
As a result, a linear actuator having a small frictional force can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a linear actuator according to the present invention. FIG. 2 is a partially omitted sectional view of a linear actuator according to the present invention. FIG. 3 is a schematic electric circuit diagram for driving a linear actuator according to the present invention. [Description of Signs] 10 Linear actuator 12 Housing 14 Slide rods 16a to 16c
... Contacts 22 ... Springs 24 ... Iron cores 26a-26f ... Coils 28c ... Cap members 28d ... Protrusions 50 ... Bearing coils 52 ... Movement members 54 ... Roller members 56 ... Brake shoes 58a and 58b
…ball bearing

Claims (1)

(57) [Claims] A linear actuator in which a plurality of coil units and a magnetic material as an iron core are disposed in a housing, and a slide rod penetrating the coil unit and the magnetic material is disposed so as to be relatively displaceable with respect to the housing. A brake shoe that presses the slide rod to brake the slide rod; a brake shoe drive member made of a magnetic material disposed between the slide rod and the housing; a housing and the brake shoe drive member A plurality of rolling members that are interposed between the guide members to guide the brake shoe driving member substantially parallel to the axis of the slide rod by rolling when braking the slide rod or releasing the brake from the slide rod. A linear actuator, comprising: a member;