JPH0337433A - Brake device - Google Patents

Abstract

PURPOSE:To enhance thinning and reduction in weight of the whole device and simplification of the structure by braking a rotating body by the elastic deformation of a first elastic body by a linear shape memory alloy contracted by electrification, keeping the braked state by a second elastic body, and releasing the braked state by the elastic deformation of the second elastic body. CONSTITUTION:When the linear shape memory alloy 3 of a first elastic body 2 is electrified, the shape memory alloy 3 is contracted, the elastic body 2 is elastically deformed and curved in the arrowed direction, and its top end part 2b is engaged with the teeth part 4a of a gear 4 to brake the gear 4. At this time, a second elastic body 5 is in a restored state, and the front surface of its top end part 5b is touched by the back surface of the top end part 2b of the elastic body 2 to keep the braked state. When a linear shape memory alloy 6 of the elastic body 5 is electrified, the shape memory alloy 6 is contracted, the elastic body 5 is contracted, elastically deformed, curved, and separated from the elastic body 2. Hence, the elastic body 2 is restored to release the brake of the gear 4. The front surface of the top end part 2b is touched by the back surface of the top end part 5b of the elastic body 5 to keep the elastic deformation of the elastic body 2.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a brake device using a shape memory alloy.

[Summary of the Invention] This invention provides a brake device using a shape memory alloy, in which a first elastic body is elastically deformed by a linear shape memory alloy that shrinks when heated by electricity, thereby braking a rotating body. While the braking state is maintained by the second elastic body, the linear shape memory alloy of the second elastic body is compressed by being heated by electricity, thereby elastically deforming the second elastic body to release the braking state. By doing so, it is possible to further reduce the thickness and weight of the entire device, and it also has a simple structure and can be manufactured at low cost.

[Prior Art] For example, Japanese Utility Model Application Publication No. 59-164134 discloses a switching mechanism for electrical equipment using a shape memory alloy. To explain this in detail with reference to FIG. 5, 10 is a VTR.
This is a switching mechanism that presses or separates the pinch roller 13 from the capstan 11 via the tape 12. This switching mechanism 10 includes a lever 15 which is pivotally supported by a pin on one end of the chassis 14 and rotatably supports the pinch roller 13 at the other end, and a pin 16 that is erected in the middle of this lever 15 and a lever 15 that is supported by a pin on the chassis 14. A toggle spring 18 is interposed between the provided pins 17 and urges the pinch roller 13 to rotate toward the capstan 11 or the stopper 19, a pin 20 provided upright near the pinch roller 13 of the lever 15, and the chassis 14. A shape memory alloy 22 in the shape of a tension coil spring is interposed between pins 21 standing upright near the capstan 11, and urges the pinch roller 13 to be pressed against the capstan 11 by heating and restoring when energized; A shape memory alloy 24 in the shape of a tension coil spring is interposed between the pin 20 and a pin 23 that stands upright near the stopper 19 of the chassis 14, and urges the pinch roller 13 toward the stopper 19 by heating and restoring when energized. has been done.

When the pinch roller 13 is pressed onto the capstan 11, the shape memory alloy 22 is energized and heated to restore it to the shape of a tension coil spring.
5 to the capstan 11 side, and
Press the pinch roller to 1 and press the pinch roller to toggle spring 1.
8 and maintained.

In addition, when the pinch roller 13 is separated from the capstan 11, the lever 1
5 toward the stopper 19, the lever 15 is brought into contact with the stopper 19, and this state is maintained by the toggle spring 18.

[Problem to be Solved by the Invention 1] However, in the conventional switching mechanism 10 and the like that utilize the shape memory alloys 22 and 24 described above, the toggle springs 18 and 18 maintain the state after operation. Since the stopper 19 and the like are indispensable, the number of parts increases and the structure becomes complicated, and the entire mechanism becomes large and the cost increases. In particular, when shape memory alloys are used in the brake equipment of the reel stand of a VTR, the installation space for the rimisota gear of the reel stand is small, so the development of an M-shaped one is desired. ing.

Therefore, the present invention provides a brake device that can be made thinner, lighter, and have fewer coils.

[Means for Solving the Problems] The brake device of the present invention elastically deforms to brake a rotary body using a linear shape memory alloy that shrinks when heated by energization, and changes the braking state of the rotary body when not energized. a linear shape memory alloy that maintains the braking state when the first elastic body brakes the rotary body and shrinks when heated by electricity; and a second elastic body which is elastically deformed so as to release the braking state of the first elastic body, and whose state is maintained by the restored first elastic body.

"Operation 1 When electricity is applied to the linear shape memory alloy of the first elastic body, the linear shape memory alloy contracts, the first elastic body elastically deforms, and brakes the rotating body. At this time, the second elastic body Since the elastic body is in its restored state and hits the first elastic body, the braking state is maintained.

Furthermore, when the linear shape memory alloy of the second elastic body is energized, the linear shape memory alloy contracts and the second elastic body is elastically deformed and separated from the first elastic body. This allows the first
The elastic body is restored and the braking of the rotating body is released. By restoring the first elastic body, the elastically deformed state of the second elastic body is maintained.

[Example] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In FIGS. 1 and 2, a brake device 1 is suitable for use in, for example, a limiter attached to a reel stand of a VTR for braking the reel stand. This brake device l is elastically deformed so as to brake a gear (rotating body) 4 by a wire-shaped shape memory alloy 3 that shrinks due to the processing in the eighth part, and also releases the braking state of the gear 4 when the power is not applied. A first elastic body 2 that restores its original shape as shown in FIG. and a second elastic body 5 which is elastically deformed so as to release the braking state of the first elastic body 2, and whose state is maintained by the restored first elastic body 2. .

The first elastic body 2 is formed from synthetic resin into a flexible arcuate arm shape, and its base 2a is fixed to the chassis 7 via a predetermined means. Further, the tip end 2b of the first elastic body 2 is formed into a tooth shape, and is connected to the gear 4.
The teeth 4a are engaged with each other and can be freely disengaged.

- The second elastic body 5 is molded from synthetic resin into a flexible arcuate arm shape, and its base 5a is about the same as the first elastic body 2 about the rotation axis 4b of the gear 4 of the sawshield 7. They are fixed at positions separated by 90 degrees via predetermined means. Then, the tip 5b of the second elastic body 5 comes into contact with the tip surface and back surface of the tip 2b of the first elastic body 2,
They are free to defect.

The wire-shaped shape memory alloys 3, 6 are fixed between the bases 2a, 5a and the tips 2b, 5b of the first and second elastic bodies 2, 5 through predetermined means, and are energized to Due to heat generation (approximately 120°C), several percent of the total length shrinks.

At both ends of each of these shape memory alloys 3.6, there are conductive wires 8,
9 are connected to each other.

The gear 4 corresponds to, for example, a limiter attached to a reel stand of a VTR that brakes the reel stand.

According to the brake device 1 of the above embodiment, the first elastic body 2
Electrify the linear shape memory alloy 3 (about a fraction of a second)
Then, as shown by the pair of arrows in FIG. 4, the linear shape memory alloy 3 contracts, and the first elastic body 2 is deformed in the direction shown by the arrows in FIGS. Bend, its tip 2b
meshes with the tooth portion 4a of the gear 4 to brake the gear 4.

At this time, as shown in FIG. 1, the second elastic body 5 is in the restored state, and the front surface of its tip 5b hits the back surface of the tip 2b of the first elastic body 2 to maintain the braking state (locked). ) to be done.

Further, the linear shape memory alloy 6 of the second elastic body 5 is energized (
(about a fraction of a second) Then, as shown by the pair of arrows in FIG. 4, the linear shape memory alloy 6 contracts, and the second elastic body 5 becomes elastic as shown by the arrows in FIG. It deforms and bends and separates from the first elastic body 2. As a result, as shown by the arrow in FIG. 2, the first elastic body 2 is restored and releases the braking of the gear 4 (unrotter). This restoration of the first elastic body 2 hits the front side of the tip 2b of the first elastic body 2 or the back side of the tip 5a of the second elastic body 5.

Thereby, the elastically deformed state of the second elastic body 2 is maintained. By repeating this, the first of the above pairs:
The gear 4 is braked and released by the elastic bodies 2 and 5 shown in FIG.

In this way, each linear shape memory alloy 3, 6 is alternately energized for a minute time to brake the gear 4 via each elastic body 2, 5.
Since the brakes are released, power consumption can be kept low. Moreover, since each of the elastic bodies 2 and 5 can also be made thicker between the gear 4 and the gear 4, the brake device 1 can be made thinner and more compact. Furthermore, since the gear 4 can be braked and released by the pair of elastic bodies 25, the number of parts can be significantly reduced and the structure can be simplified, and the brake device 1 can be Can be manufactured at low cost.

In addition, according to the above embodiment, a wire shape was used as the linear shape memory alloy, but the shape is not limited to this, and a shape such as a coil spring shape may be used.

Further, although the brake device has been described, it goes without saying that the present invention can also be applied to switching devices for various types of electrical equipment.

[Effects of the Invention] As described above, according to the brake device of the present invention, the first elastic body is elastically deformed by the linear shape memory alloy that shrinks when heated by electricity to brake the rotary body, and this braking state is maintained by the second elastic body, and the second elastic body is elastically deformed by shrinkage due to heating of the linear shape memory alloy of the second JII body by energization, thereby releasing the braking state. This makes it possible to further reduce the thickness and weight of the entire device, and also to simplify the structure, allowing the device to be manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing a braking state of a brake device according to an embodiment of the present invention, FIG. 2 is a schematic plan view showing a non-braking state of the brake device, and FIG. 3 is a schematic plan view showing a non-braking state of the brake device. 4 is a schematic explanatory diagram showing the state of a linear shape memory alloy and an elastic body when energized. Figure 5 is a schematic explanatory diagram showing the state of a linear shape memory alloy and an elastic body when energized. FIG. 2 is a perspective view of an example. brake device, 2... first supra-extension body, 3... linear shape memory alloy, 4... gear (co-moving body), 5. second elastic body, linear shape memory alloy. JP-A-3 37433 (5)

Claims (1)

[Claims] (1) A first elastic body that is elastically deformed so as to brake the rotating body by a linear shape memory alloy that shrinks when heated by electricity, and restores itself to release the braking state of the rotating body when electricity is not applied; , When the first elastic body brakes the rotating body, the braking state is maintained, and the braking state of the first elastic body is released by a linear shape memory alloy that shrinks when heated by electricity. and a second elastic body that is elastically deformed and maintained in its state by the restored first elastic body.