JPH0281961A - Bistable shape memory alloy device - Google Patents

Abstract

PURPOSE:To prevent both shape memory alloys from generating the permanent deformation by separating simultaneous shape restoration-preventing contacts and stopping electrification for the shape memory alloy, in a case such that before one of the shape memory alloys is sufficiently cooled, the other shape memory alloy is heated. CONSTITUTION:In emergency, before the first or second shape memory alloy 14 or 16 is sufficiently cooled, the other shape memory alloy is electrified and heated, when both the shape memory alloys 14, 16 are placed in a condition of pulling each other, a movable member 1 is moved along a long hole 2 for a shaft-shaped contact 3 against a bow-shaped spring 13, and a movable member side contact 4 is separated from the shaft-shaped contact 3. Consequently, electrification is stopped to the shape memory alloys 14, 16, so that both of them are prevented from simultaneously applying shape restoring force to each other generating the permanent deformation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a bistable shape memory alloy device that includes a pair of shape memory alloys as drive sources and has two stable states.

[Conventional technology]

In this type of device, the shape-recovery force of one shape-memory alloy causes the device to transition from one stable state to the other stable state, and conversely, the shape-recovery force of the other shape-memory alloy causes the device to transition from the other stable state. state to the one stable state.

[Problem to be solved by the invention]

However, in conventional devices of this type, if one shape memory alloy is heated before the other shape memory alloy is sufficiently cooled, both shape memory alloys simultaneously exert a shape recovery force on each other, causing a permanent There was a drawback that the device would become deformed and the device would not work properly.

The present invention was made in view of the above circumstances, and even if one shape memory alloy is heated before the other shape memory alloy is sufficiently cooled, both shape memory alloys can simultaneously exert shape recovery force. It is an object of the present invention to provide a bistable shape memory alloy device that does not undergo permanent deformation due to interaction.

[Means to solve the problem]

The bistable shape memory alloy device according to the present invention includes a movable member movable between a first position and a second position, and the movable member is linked to the movable member, and the movable member is moved to the first position during shape recovery. a first shape memory alloy that exerts a shape restoring force to cause the movable member to move toward the second position; a second shape memory alloy that exerts a shape recovery force so as to bias the movable member toward the first position when the movable member is closer to the first position than the predetermined position; On the other hand, a movable member biasing spring that biases the movable member toward the second position when the movable member is closer to the second position than the predetermined position;
contacts for preventing simultaneous shape recovery, which are normally in contact with each other, but are separated from each other when the first and second shape memory alloys simultaneously generate a shape recovery force of a predetermined magnitude or more; It has a first current path and a second current path that respectively flow current through the first and second shape memory alloys through this contact for preventing simultaneous shape recovery.

[Effect]

In the present invention, if one shape memory alloy is heated before the other shape memory alloy is sufficiently cooled, the contacts for preventing simultaneous shape recovery are separated and the current supply to the shape memory alloy is stopped. It is possible to prevent the shape-recovery forces of the shape-memory alloys from acting on each other.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

1 to 7 show an embodiment of the present invention. In this embodiment, an elongated hole 2 extending parallel to the lower side 1b of the movable member 1 is provided in the center of the upper side 1a of the roughly T-shaped movable member 1 made of an insulator. The figure shows movable member 1
(shown alone). The elongated hole 2 is penetrated by a ring-shaped contact 3 made of a conductor, so that the movable part can rotate around the axial contact 3 and move in the direction of the elongated hole 2 with respect to the axial contact 3. It is movable.

A plate-shaped movable member side contact 4 (FIG. 5 shows this movable member side contact 4 alone) is fixed to the surface of the upper side 1a of the movable member 1, and this movable member side contact 4 has a A recess 5 is provided to expose the elongated hole 2 of the movable member 1. The lower end of the four parts 5 and the lower end of the elongated hole 2 are made to be at the same height, or the lower end of the recessed part 5 is made higher than the lower end of the elongated hole 2. Here, the shaft-shaped contact 3 and the movable member side contact 4 constitute the simultaneous shape recovery prevention contact of the present invention in this embodiment.

An insulator 6 whose positional relationship is fixed with respect to the shaft-shaped contact 3 is provided below the lower side portion 1b of the movable member 1. This insulator 6 supports the lower ends of a common leaf spring 7, a first leaf spring 8, and a second leaf spring 9, each made of a good conductor. The left side of the leaf spring 7 and the second leaf spring 9 are arranged on the right side of the common leaf spring 7, respectively. A common contact 10 for switching the current supply is provided at a portion slightly below the upper end of the common leaf spring 7. A first energization switching contact 11 is provided at the upper end of the first leaf spring 8, and a second energization switching contact 12 is provided at the upper end of the second leaf spring 9.

Here, in this embodiment, the first contact 11 and the common contact 10 constitute a first energization switching contact pair of the present invention,
The second contact 12 and the common contact 10 constitute a second energization switching contact pair of the present invention.

A bow spring 13 is interposed between the upper end of the common leaf spring 7 and the lower end of the lower side 1b of the movable member 1. When the movable member 1 is tilted to the right, the movable member 1 is biased clockwise and the common leaf spring 7 is biased toward the second leaf spring 9 to bring the common contact 10 into contact with the second contact 12, while the movable member 1 is biased clockwise. When the member 1 is tilted to the left as shown in FIG. The first contact point 11 is contacted.

The upper end of a wire-shaped first shape memory alloy 14 made of a Ti-Ni alloy or the like is attached to the left end of the movable member 1 in the drawing, and the lower end of this first shape memory alloy 14 is an insulating material. It is attached to the body 6. The upper end of a wire-shaped second shape memory alloy 16 made of a Ti-Ni alloy or the like is attached to the right end of the movable member 1 in the drawing, and the lower end of this second shape memory alloy 16 is insulated. It is attached to the body 6. Here, when the first shape memory alloy 14 and the second shape memory alloy 16 return to their memorized lengths, the movable member 1 tilts toward the shape memory alloys. Memorizes different lengths. Further, the upper ends of the first shape memory alloy 14 and the second shape memory alloy 16 are electrically connected to the movable member side contact 4.

6 and 7 mainly represent the electrical connection relationship of this device, and the mechanical (1M configuration is a simplified diagram). As shown in these figures, the first and second shape memory A diode D and a diode D2 are inserted in series and in the same direction between the lower ends of the alloy 14.16, and the connection point of these diodes D and D2 is connected to one power input terminal 17. Power input terminal 18
is connected to the first contact 11 via a diode D3, and is also connected to the second contact 12 via a diode D4 having a direction opposite to that of the diode D3.

Further, the shaft-shaped contact 3 is electrically connected to the common leaf spring 7.

Next, the operation of this embodiment will be explained.

1 and 6 show a state in which the movable member 1 is in the second position in this embodiment, and in this state,
The movable member 1 is inclined at a predetermined angle to the right (to the second shape memory alloy 16 side), and the common contact 10 is in contact with the second contact 12. In this state, when a voltage with a polarity such that the input terminal 17 side is (+) and the input terminal 18 side is (-) is applied to the input terminals 17 and 18, the input terminal 17 - the diode D1 - the first shape memory alloy 14 - Movable member side contact 4-
Current flows through the paths of the axial contact 3 - the common leaf spring 7 and the common contact 10 - the second contact 12 and the second leaf spring 9 - the diode D4 - the input terminal 18. As a result, the first shape memory alloy 14 is heated to a predetermined temperature range by Joule heat, and due to the shape memory effect, it contracts in an attempt to return to the memorized length, so the movable member 1 moves counterclockwise. Rotate and go.

At this time, the bow spring 13 initially resists the rotation of the movable member 1, but when the movable member 1 exceeds the neutral position and tilts to the left in the figure, the shape recovery force of the first shape memory alloy 14 increases. The common contact 1 is biased in the forward direction, that is, the movable member 1 is urged to rotate further to the left (counterclockwise).
0 is biased toward the first contact 11 side. Therefore, as shown in FIGS. 2 and 7, the movable member 1 is now tilted to the left (towards the first shape memory alloy 14) at a predetermined angle. This position is the first position of the movable member 1 in this embodiment, and in this state, the common contact 10 is separated from the second contact 12 and is in contact with the first contact 11, so that the first shape The current supply to the memory alloy 14 is stopped.

Next, with the movable member 1 in the first position as shown in Figs. When a voltage with a polarity such that the 18 side becomes (+) is applied, the input terminal 18 - the diode D3 - the first leaf spring 8 and the first contact 11 - the common contact 10 and the common leaf spring 7 -
Axial contact 3 - Movable member side contact 4 - Second shape memory alloy 1
A current flows through the path 6-diode D2-input terminal 17. As a result, the second shape memory alloy 16 is heated to a predetermined temperature range by Joule heat, and due to the shape memory effect, it contracts in an attempt to return to the memorized length, so the movable member 1 rotates clockwise. move on.

At this time, the bow spring 13 initially resists the rotation of the movable member 1, but when the movable member 1 exceeds the neutral position and tilts to the right in FIG. In other words, the movable member 1 is urged to rotate more clockwise, and the common contact 10 is urged toward the first contact 11. Therefore, the movable member 1 returns to the second position shown in FIGS. 1 and 6, the common contact 10 is separated from the first contact 11 and comes into contact with the second contact 2, and the second shape memory alloy 16
The energization is stopped.

In this way, this device has two states in which the movable member 1 is in the first position (the states shown in Figs. 2 and 7) and in the second position (the states shown in Figs. 1 and 6). It can assume a stable state, and can freely transition from one of the two stable states to the other by selecting the polarity of the voltage applied to the power supply input terminals 17,18.

In the unlikely event that the first shape memory alloy 14 or the second shape memory alloy 16 is not sufficiently cooled, the other shape memory alloy is electrically heated and both shape memory alloys 14.
16 are pulled together, the movable member 1 moves along the elongated hole 2 with respect to the axial contact 3 against the bow spring 13 as shown in FIG. 3, and the movable member side contact 4 is separated from the axial contact 3, the current supply to the shape memory alloy 14.16 is stopped, and both shape memory alloys 14.16
This prevents them from being permanently deformed by applying shape restoring forces to each other at the same time.

In addition, in this embodiment, as described above, by the action of the common contact 10, the first contact 11, the second contact 12, etc., the first shape memory alloy 14 is energized to move the movable member 1 to the second shape. When rotating the movable member 1 from the first position to the first position, the first shape memory alloy 14 is automatically de-energized, and the second shape memory alloy 16 is energized to rotate the movable member 1 from the first position to the first position. When the second shape memory alloy 14 is rotated to the second position, the power supply to the second shape memory alloy 16 is automatically stopped, thereby preventing the shape memory alloy 14 and 16 from overheating.

Figures 8-9 show other embodiments of the invention.

A rod-shaped movable member 22 made of a good conductor is mounted on the base 21 so as to be slidable in a linear direction (horizontal direction in the figure). Energization switching contacts 23 and 24 are attached to both ends of the base 21, respectively, and these contacts 23 and 24
is the energization switching contact 25 attached to the movable member 22.
26, respectively. Here, the energization switching contacts 23 and 25 constitute a first energization switching contact pair in this embodiment, and the energization switching contacts 2
4 and 26 constitute switching contacts in the second passage 7 in this embodiment. In addition, the contacts 25 and 26 also function as stoppers, and these contacts 25 and 26 also function as stoppers.
When the contacts 23 and 24 come into contact with 5.26, the movable member 22 can no longer move in the direction of movement.

A slide shaft 27 is provided in a direction parallel to the sliding direction of the movable member 22, and a spring support 28 is provided on this slide shaft 27 so as to be slidable along the slide shaft 27.
are fitted. The spring support body 28 and the movable member 22
A bow spring 29 is interposed between the bow spring 2 and
9, when the spring support 28 is to the left of a predetermined boundary position with respect to the movable member 22, it biases the spring support 28 to the left and the movable member 22 to the right; In addition, when the spring support 28 is to the right of the predetermined boundary position with respect to the movable member 22, the spring support 28 is biased to the right and the movable member 22 is biased to the left. . Note that the bow spring 29 is electrically insulated from the movable member 22.

The spring support body 28 supports the lower ends of a plate-shaped common contact 30 for preventing simultaneous shape recovery, and a first plate spring 31 and a second plate spring 32 made of a good conductor, respectively.
In the figure, the first leaf spring 31 is arranged on the left side of the common contact 30, and the second leaf spring 32 is arranged on the right side. Said first leaf spring 3
A first simultaneous shape recovery prevention contact 33 is provided at the upper end of the leaf spring 1 , and a second simultaneous shape recovery prevention contact 34 is provided at the upper end of the second leaf spring 32 .
．． 34 are normally brought into contact with the common contact 30 by the elasticity of leaf springs 31 and 32. And the common contact 30
is electrically connected to one pole of a power source 35, and the other pole of this power source 35 is connected to the movable member 22.

Between the first contact point 33 and a support member 36 provided to the left of the contact point 33, a wire-shaped first shape memory alloy 37 made of a Ti-Ni alloy or the like is substantially a movable member. 2
It is passed in a direction parallel to the sliding direction of 2. The second contact point 34 and the support member 3 provided on the right side of this contact point 34
A wire-shaped second shape memory alloy 39 made of a Ti--Ni alloy or the like is passed between the movable member 22 and the movable member 8 in a direction substantially parallel to the sliding direction of the movable member 22. Here, the support material 36
and 38 are fixed in position relative to the base 21. Further, the first shape memory alloy 37 and the second shape memory alloy 39 each have a memorized length slightly shorter than half of the distance between the supporting members 36 and 38.

The left end of the first shape memory alloy 37 is connected to the contact 23 via a switch 40, and the right end of the second shape memory alloy 39 is connected to the contact 23 via a switch 41.

Next, the operation of this embodiment will be explained.

In FIG. 8, spring support 28 has moved to the right, and bow spring 29 urges movable member 22 to the left to move it to the extreme left, bringing contacts 24, 26 into contact. This eighth
The position of the movable member 22 in the figure is the second position of the movable member 22 in this embodiment.

In this state, switch 41 is open and switch 41 is open.
If 0 is closed, power supply 35 - common contact 30 - first contact 3
3-first shape memory alloy 37-switch 40-contact 24
．． A current flows in the path of 26-movable member 22-power source 35,
The first shape memory alloy 37 is heated to a predetermined temperature range and contracts due to the shape memory effect in an attempt to return to the memorized length. Stretch the spring support 28 to the left via the
The spring support 28 is moved to the left.

At this time, the bow spring 29 initially resists the leftward movement of the spring support 28, but the spring support 28
2, the spring support body 28 is biased to the left and the movable member 2
2 to the right. As a result, the movable member 22 moves to the right until the contact 25 comes into contact with the contact 23, as shown in FIG. 9, and then stops there. This rightmost position in FIG. 9 is the first position of the movable member 22 in this embodiment.

Note that when the movable member 22 begins to move to the right, the contact point 2
4.26 is separated and the electricity supply to the first shape memory alloy 37 is stopped at that point, so the first shape memory alloy 3
7 overheating is prevented.

Next, as shown in FIG. 9, the movable member 22 moves to the rightmost side,
When the contacts 23 and 25 are in contact and the first shape memory alloy 37 is sufficiently cooled, the switch 40 is opened and the switch 41 is closed.
〇-Second contact 34-Second shape memory alloy 39-Switch 41-Contact 23.25-Movable member 22-Power source 35 A current flows through the path, and the second shape memory alloy 39 reaches a predetermined temperature range. The second shape memory alloy 39 is heated to the spring support 28 via the second spring plate 32 and contracts due to the shape memory effect in an attempt to return to the memorized length.
is pulled to the right, and the spring support body 28 is moved to the right. At this time, the bow spring 29 is initially
However, when the spring support body 28 comes to the right side of the boundary position with respect to the movable member 22, the spring support body 28 is biased rightward and the movement The member 22 is now biased to the left. As a result, the movable member 22 returns to the rightmost position (second position) where the contact 25 contacts the contact 23 in FIG. 8, and stops there.

Note that when the movable member 22 begins to move to the left, the contact point 2
3.25 is separated and the electricity supply to the second shape memory alloy 39 is stopped at that point, so the second shape memory alloy 3
9 overheating is prevented.

In this way, in this device, the movable member 22 is located on the leftmost side (
The movable member 22 can take two stable states: a state in which the movable member 22 moves to the rightmost position (first position), and a state in which the movable member 22 moves to the rightmost position (first position). By heating the first and second shape memory alloys 37, 39, they can be freely transitioned from one of said two stable states to the other.

In the unlikely event that the first shape memory alloy 37 or the second shape memory alloy 39 is not sufficiently cooled, the other shape memory alloy is electrically heated and both shape memory alloys 37.
39 are pulled together, the 10th
From the common contact 30 to the first and second contacts 33 as shown
．． 34 are spaced apart, so that the shape memory alloy 37 or 39
The current supply to the shape memory alloys 37 and 39 is stopped, thereby preventing the shape memory alloys 37 and 39 from being permanently deformed by applying shape recovery force to each other at the same time.

Furthermore, in this embodiment, the movable portion 22 is a spring (spring plate 3
3.34 and the shape memory alloy 37 via the bow spring 29)
．． 39, even if an overload is applied to the movable member 22, the overload does not directly act on the shape memory alloy 37, 39. When the shape memory alloy 37 or 39 is energized while the movable member 22 cannot move due to overload, the contact 33 or 34 is pulled by the shape memory alloy 37 or 39 and separated from the common contact 30. , the power supply to the shape memory alloy 37 or 39 is stopped, and further heating of the shape memory alloy 37 or 39 is prevented, so even if an overload is applied, the shape memory alloy 37.
39 will not be damaged.

〔Effect of the invention〕

As described above, in the present invention, even if one shape memory alloy is heated before the other shape memory alloy is sufficiently cooled, both shape memory alloys simultaneously exert a shape recovery force on each other and are permanently deformed. This provides an excellent effect of not storing it away.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the shape memory alloy device according to the present invention.
FIG. 2 is a front view showing the embodiment in one stable state, FIG. 3 is a front view showing the embodiment in another stable state, and FIG. ;tc! 4 is a front view showing the movable member 22 in this embodiment, FIG. 5 is a front view showing the movable member side contact 4 in this embodiment, FIG. FIG. 7 is a schematic configuration diagram mainly showing electrical connections and a simplified mechanical configuration, and FIG. 8 is a front view showing another embodiment of the present invention in a stable state. FIG. 9 is a front view showing the embodiment in another stable state, and FIG. 10 is a front view showing the embodiment in a state where one shape memory alloy is heated before the other shape memory alloy is sufficiently cooled. It is a front view. 1... Movable member, 2... Elongated hole, 3... Axial contact,
4... Movable member side contact, 11... First energization switching contact, 12... Second energization switching contact, 13... Bow spring, 14... First shape memory alloy , 16... second shape memory alloy, 22... movable member, 23.24...
・First energization switching contact, 25.26... Second energization switching contact, 28... Spring support, 29... Bow spring, 30... Common contact for preventing simultaneous shape recovery, 31...
First leaf spring, 32... Second leaf spring, 33... First contact for preventing simultaneous shape recovery, 34... Second contact for preventing simultaneous shape recovery, 37... First shape memory alloy, 3
9...Second shape memory alloy. Figure 1 Figure 2

Claims (1)

[Claims] 1. A movable member that is movable between a first position and a second position, and a movable member that is linked to the movable member and that moves the movable member toward the first position when the shape is restored. a first shape memory alloy that applies a shape restoring force so as to cause the movable member to move toward the second position; a second shape memory alloy that applies a shape recovery force to the second shape memory alloy; a movable member biasing spring that biases the movable member toward the second position when the movable member is closer to the second position than the predetermined position; When the first and second shape memory alloys simultaneously generate a shape recovery force of a predetermined magnitude or more, a simultaneous shape recovery prevention contact is separated from each other, and the simultaneous shape recovery prevention contact is connected to the A bistable shape memory alloy device comprising a first current path and a second current path for passing current through the first and second shape memory alloys, respectively. 2. They are provided in the first current path, and are in contact with each other when the movable members are in the first position, but are separated from each other when the movable members move to the second position. A first energization switching contact pair is provided in the second current path, and when the movable member is in the second position, they are in contact with each other, but when the movable member is in the first 2. The bistable shape memory alloy device according to claim 1, further comprising a second energization switching contact pair that separates from each other when moved to the position. 3. A shaft-like contact, and a shaft-like contact that is rotatable between the first position and the second position about the shaft-like contact and movable in a predetermined movement direction with respect to the shaft-like contact. the movable member supported by the axial contact, the movable member side contact attached to the movable member, and the movable member biased in a direction in which the movable member side contact comes into contact with the axial contact. The bistable shape memory alloy device according to claim 1 or 2, further comprising a spring that acts as a spring, wherein the axial contact and the movable member side contact constitute the contact for preventing simultaneous shape recovery. 4. The movable member movable in a linear direction, a spring support movable in a direction parallel to the linear direction, a common contact supported by the spring support, and a first contact supported by the spring support. a spring body, a second spring body, and the first spring body, and the elasticity of the first spring body causes the common contact to move from the first position side toward the second position side. provided on a first contact point to be pressed and the second spring body,
between a second contact point that is pressed against the common contact point from the second position side toward the first position side by the elasticity of the second spring body, and the movable member and the spring support body. An interposed movable member biasing spring acts to apply a shape recovery force to the spring support body through the first spring body when the shape is restored, so as to move the spring support body toward the first position. The first shape memory alloy acts on the spring support body through the second spring body to cause a shape recovery force to move the spring support body toward the second position during shape recovery. and the second shape memory alloy, and the movable member biasing spring is biased toward the spring support when the spring support is closer to the first position than the predetermined boundary position with respect to the movable member. is biased toward the first position and the movable member toward the second position, and the spring support is located closer to the second position than the predetermined boundary position with respect to the movable member. , the spring support is biased toward the second position and the movable member is biased toward the first position, and the common contact and the first 3. The bistable shape memory alloy device according to claim 1, wherein the contact and the second contact constitute the contact for preventing simultaneous shape recovery.