JP2001082569A - Electric linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a rise in temperature by frictional heat and prolong the life of brake mechanisms such as brake shoes. SOLUTION: A brake mechanism 5 includes a disk with elasticity, such as a leaf 6, mounted on a screw shaft 4 or a rotary shaft, brake shoes 7 fixed to one surface of the disk, a friction element 10a for generating frictional force against the brake shoes 7, a ball 8 disposed for contact with the other surface of the disk, and an annular raceway 9 with a partly shallow bottom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electric linear actuator having a brake mechanism.

[0002]

2. Description of the Related Art In a conventional electric linear actuator, after the electric linear actuator is turned off and stopped, there is a possibility that a moving body attached to the electric linear actuator falls naturally due to the weight of the moving body. In this case, a brake mechanism is used to prevent the moving body from falling.

The brake mechanism mainly uses an electromagnetic brake, a sliding brake, or the like.

[0004]

However, for example, an electromagnetic brake requires two power supplies, a power supply for operating the electric linear actuator and a power supply for the electromagnetic brake, and is expensive due to its complicated structure. became.

[0005] The sliding brake is a brake shoe,
A material having a high frictional force such as an O-ring is used.
In order to apply a brake by frictional force and to make the brake mechanism a simple structure, it is necessary to always apply a large frictional force to the structure. Arising brake shoe, O
The ring and the like were worn, shortening the service life and causing a problem.

[0006]

Therefore, according to the present invention, there is provided a disk plate attached to a screw shaft or a rotating shaft and having an elastic force, and fixedly provided on one side surface of the disk plate. A brake shoe, a friction body for generating a frictional force with the brake shoe, a ball provided so as to be in contact with the other side surface of the disc plate, and a ring for disposing the ball. An electric linear actuator, comprising: a brake mechanism provided in a shape and having a through groove formed with a shallow bottom at a portion of a portion.

[0007]

[Function] A disk-shaped spring plate is attached to a screw shaft or a rotating shaft. Then, one side surface of a disc-shaped brake shoe is fixed to one side surface of the spring plate. Then, the ball is brought into contact with the other side surface of the spring plate. Then, this ball is disposed in the passage groove.

[0008] The other side surface of the brake shoe is in contact with a friction member provided on the casing.

As described above, the spring plate is sandwiched between the brake shoe and the ball. However, when the electric actuator is normally operated, the ball is located in the passage groove. Since the side surface of the plate is lightly contacted, the spring plate and the brake shoe are pressed with a small force, and the braking force is in a small state.

When the power of the electric actuator is turned off to reduce the motor torque to zero, an external force causes
As the screw shaft is turned, the ball moves in the passage groove and rides on the protrusion. When the ball rides on the protrusion, the force holding the spring plate between the brake shoe and the ball increases,
That is, the brake torque increases and the rotation of the spring plate is stopped. Therefore, the position of the moving body can be held at this position.

When the power of the motor is turned on, the spring plate starts rotating, and the ball passes over the convex portion and moves to a normal position in the groove.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a partial sectional side view of a brake mechanism of an electric actuator according to the present invention. FIG. 2 is a front view of the groove as the ball is provided. FIG.
FIG. 4 is a development view of a groove as a ball is provided.

In FIG. 1, an electric actuator 1 is
A motor (not shown) as a driving source, a first gear 2 provided at the shaft end of the motor, a second gear 3 meshed with the first gear 2, and a second gear 3 , A brake mechanism 5 attached to one end of the screw shaft 4, a moving body (not shown) screwed to the screw portion 4 a of the screw shaft 4, and a casing containing these members 10.

The brake mechanism 5 includes a disk-shaped spring plate 6 attached to the screw shaft 4, a disk-shaped brake shoe 7 fixedly provided on one side of the spring plate 6, and a spring plate. 6 is made of a steel or resin ball 8 provided so as to be in contact with the other side surface. The other side surface of the brake shoe 7 is configured to be in contact with a friction body 10a provided on the casing 10 and formed of a metal plate or the like.

When the motor is driven, the screw shaft 4 rotates via the first gear 2 and the second gear 3. When the screw shaft 4 rotates, the spring plate 6 also rotates at the same time. The spring plate 6 and the brake shoe 7 fixed to the spring plate 6 are braked by being sandwiched between the friction member 10a of the casing and the ball 8.

The spring plate 6 has an arbitrary elastic force, and can bend when pressed against the ball 8.

In FIG. 2 and FIG.
Are arranged in the groove 9 as provided in a ring shape,
It can move inside the passage groove 9. In addition, a convex portion is provided at a part of the bottom of the passage groove 9 to make the bottom shallow.

When the electric actuator 1 is operating normally, the ball 8 of the brake mechanism 5 and the side surface of the spring plate 6 are configured to make light contact. Therefore, the braking force is set low. The ball 8
Is stationary at that location, or stays at a position pressed against the side surface of the convex portion 9a provided in the passage groove 9.

When the power of the electric actuator 1 is turned off and the motor torque is reduced to zero, when the spring plate 6 is rotated by an external force such as the own weight of the moving body, the force of pressing the ball 8 against the spring plate 6 is strong. In other words, it moves in the passage groove 9 and rides on the projection 9a. Then, the ball 8 becomes the convex portion 9
When the rider rides on a, the force holding the spring plate 6 between the brake shoe 7 and the ball 8 increases, that is, the brake torque increases, and the rotation of the spring plate 6 is stopped.
Therefore, the position of the moving body can be held at this position.

Since the brake torque at this time is much smaller than the motor torque, when the power of the motor is turned on, the spring plate 6 starts rotating, and the ball 8 may get over the convex portion 9a. Then, it moves to the normal position of the passage groove 9.

As described above, by configuring the brake mechanism, the frictional force constantly applied to the brake shoe of the conventional brake mechanism is reduced, so that the degree of wear of the brake shoe is reduced and the life can be extended. further,
Output loss in the brake mechanism is reduced, and an efficient electric actuator can be provided.

Instead of the spring plate 6 used in the brake mechanism 8, a disk plate having little or no elasticity may be used. At this time, an elastic body such as rubber is interposed between the mounting portion of the disk plate and the screw shaft, so that the disk plate has elasticity.

In addition to mounting the brake mechanism on the screw shaft as described above, the brake mechanism may be mounted on another rotary shaft mechanically connected to the screw shaft.

[0024]

According to the present invention, the brake torque is increased only instantaneously without applying a large brake torque at all times, so that a temperature rise due to frictional heat can be suppressed, and the life of a brake mechanism such as a brake shoe can be extended. Can be extended.

[0025]

[Brief description of the drawings]

FIG. 1 is a partial sectional side view of a brake mechanism of an electric actuator according to the present invention.

FIG. 2 is a front view of a groove in which a ball is provided.

FIG. 3 is a development view of a groove as a ball is provided.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electric actuator 2 ... 1st gear 3 ... 2nd gear 4 ... Screw shaft 5 ... Brake mechanism 6 ... Spring plate 7 ... Brake shoe 8 ... Ball 9 ... Through groove 9a ... Convex part 10 ... Casing 10a ... Friction body

Claims (1)

[Claims] 1. An electric linear actuator having a brake mechanism, comprising: a disk plate attached to a screw shaft or a rotating shaft and having an elastic force; and a brake fixed to one side surface of the disk plate. A shoe, a friction body for generating a frictional force with the brake shoe, a ball provided so as to be in contact with the other side surface of the disk plate, and a ring shape for disposing the ball. An electric linear actuator, comprising: a brake mechanism provided with a through groove having a shallow bottom formed at a part of a portion.