JPH0660628B2 - Thermo-mechanical energy converter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermodynamic energy conversion device for converting thermal energy into mechanical energy using a shape memory alloy.

[Prior art]

Generally, when the shape memory alloy is repeatedly deformed and restored, the memorized shape of the shape memory alloy is not stable and changes until the repeating operation is performed a considerable number of times. For example, in the case of a thin wire of a Ti-Ni alloy that is a type of shape memory alloy, the thin wire is stretched and deformed by applying tensile stress in a stress range (300 MPa) where shape recovery is possible, and then the thin wire is heated to shape to recover (i.e., to shrink the length of the memory shape) variations that - if allowed repeated shape recovery operation, this repeated operation is performed ¹⁰⁵ times, fine line memory shape of the Ti-Ni alloy is 20% It will grow near.

Therefore, in the conventional thermo-mechanical energy conversion device using a shape memory alloy, while the shape memory alloy is repeatedly subjected to the deformation-shape recovery operation, the operation range of the shape memory alloy fluctuates greatly, and the device However, there was an inconvenience that it would not function properly. Then, in order to prevent such an inconvenience, it is necessary to frequently perform an adjusting operation for operating the shape memory alloy in a normal operating range.

[Object of the Invention]

The present invention has been made in order to solve the above-mentioned conventional drawbacks, and a driven body driven by the shape memory alloy even if the operation range of the shape memory alloy changes due to repeated deformation-shape recovery operations. The operating range is always within a predetermined range so that the device can always function normally, the structure is simple, and the driven body can be driven at high speed with a large force. An object is to provide a conversion device.

[Means for Solving the Problems]

The thermo-dynamic energy conversion device according to the present invention includes a rotatable pulley, a driven body that is mechanically linked to the pulley to move in conjunction with the pulley, and a movable body of the driven body. A control means for controlling the range to a fixed range and a linear shape memory alloy alone, or a linear non-shape memory alloy material connected in series to the linear shape memory alloy, and wound around the pulley. A wrapping material, and a spring means that is connected to one end of the wrapping material and that applies a tensile force to the shape memory alloy, and the torque transmitted from the wrapping material to the pulley. Is a predetermined size, the wrapping material slips with respect to the pulley.

[Action]

In the present invention, when the shape memory alloy is not heated, a tensile force is applied to the spring means, so that the shape memory alloy undergoes elongation deformation as compared with the memorized length. On the other hand, when the shape memory alloy is heated to a predetermined temperature zone, the shape memory alloy shrinks in an attempt to return to the length memorized, and the driven body is driven via the pulley. As a result, when the driven body reaches one of the movement limit positions and becomes immobile, the torque transmitted from the shape memory alloy to the pulley reaches a predetermined magnitude, and the wrapping material slips on the pulley.

When the heating of the shape memory alloy is stopped, the tensile force of the spring means causes the shape memory alloy to undergo extension deformation again, and drives the driven body through the pulley in the direction opposite to that during heating. As a result, when the driven body reaches the other movement limit position and becomes immobile, the torque transmitted from the wrapping material to the pulley reaches a predetermined magnitude, and the wrapping material slips on the pulley.

As a result, even if the operation range of the shape memory alloy changes due to the repeated deformation-shape recovery operation, the operation range of the driven body driven by the shape memory alloy is always set to the predetermined range. Can always function normally.

Further, the shape recovery force of the shape memory alloy is significantly larger in the case of shape recovery from extensional deformation than in the case of shape recovery from bending deformation or torsional deformation. And with this,
The speed at which the shape memory alloy recovers from the deformed state to the memorized shape is also higher than that in the case of shape recovery from bending deformation and torsional deformation.
It is significantly faster in the case of shape recovery from extensional deformation.

This is for the following reason. The shape recovery force of the shape memory alloy increases as the deformation amount of the shape memory alloy increases within a certain range. However, looking at the cross section of the shape memory alloy, in the case of bending or torsional deformation, the entire cross section does not deform uniformly, but the amount of deformation decreases as it approaches the center, Since the amount of deformation is zero, the amount of deformation of the entire cross section is small, and thus the shape recovery force is small as a whole. However, in the case of tensile deformation of a linear or rod-shaped shape memory alloy, ideally, the shape is uniformly deformed over the entire cross section, so the shape recovery force becomes large as a whole (in other words, bending deformation or torsion). In the case of deformation, since the vicinity of the center of the shape memory alloy does not contribute to the generation of the shape recovery force, the efficiency of generating the shape recovery force is inferior, but in the case of elongation deformation of the linear or rod-shaped shape memory alloy, the shape memory alloy Since the vicinity of the center also contributes to the generation of the shape recovery force, the efficiency of the shape recovery force generation is good).

Therefore, when the same cross-sectional area is used for a linear or rod-shaped shape memory alloy, the shape recovery force of the shape memory alloy is greater than that of the shape recovery from bending deformation and torsional deformation as described above. In this case, the size becomes significantly larger, and the speed of shape recovery becomes faster.

Here, in the present invention, since the driven body is driven via the pulley by the shape recovery force from the elongation deformation of the linear shape memory alloy, the driven body can be driven at a high speed with a large force.

〔Example〕

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

FIG. 1 shows an embodiment of the present invention. In this embodiment, a pulley 1 is supported on a base 1 so as to be rotatable around a shaft 3, and the pulley 2 has an arm-shaped cover. One end of the driving body 4 is fixed. The operating range of the driven body 4 is regulated by the stoppers 5 and 6 within the constant angle range θ.

A winding material 7 made of only a linear shape memory alloy such as a Ti—Ni alloy is wound around the pulley 2, and one end portion of the winding material 7 is attached to a fixing member 8. Here, the fixing member 8 has its positional relationship fixed with respect to the base 1. By selecting an appropriate material as the constituent material of the pulley 2, the coefficient of friction between the pulley 2 and the wrapping material 7 is set to an appropriate value, and the friction coefficient is transmitted from the wrapping material 7 to the pulley 2. When the torque reaches a predetermined value, the wrapping material 7 slips on the pulley 2, and no more torque is transmitted from the wrapping material 7 to the pulley 2.

The other end of the wrapping material 7 is connected to one end of a tension coil spring 9, and the other end of the spring 9 is attached to a fixing member 8. An energizing device (not shown) is connected to both ends of the wrapping material 7.

In this case, the linear shape-memory alloy forming the wrapping material 7 remembers the straight shape, but as will become apparent later, in this embodiment, the length of the shape-memory alloy is exclusively used. Since it operates by utilizing deformation in direction and shape recovery (that is, expansion and contraction of the shape memory alloy), it does not matter even if the shape memory alloy remembers a curved shape.

Next, the operation of this embodiment will be described.

When the wrapping material 7 is not energized from the energizing device and the wrapping material 7 is being cooled, the wrapping material 7 has a size Δ from the memory shape due to the force of the spring 9.
It is stretched and deformed by L. Therefore, the pulley 2
Is in the most clockwise direction in the figure (in this state, the point A on the pulley 2 is in the position shown in FIG. 1).

Next, when an appropriate amount of current is applied to the wrapping material 7 from the current-carrying device, the wrapping material 7 is heated by Joule heat and starts to undergo phase transformation when the temperature rises above a predetermined temperature, resulting in a shape memory effect. Tries to return to the memory shape. Therefore, the wrapping material 7 shrinks toward the length of the memorized shape (note that since the wrapping material 7 is linear, the recovery stress from bending deformation is small, and therefore the bending deformation is extremely small. It only shows a good shape recovery).

Then, as the wrapping material 7 contracts, the pulley 2 rotates counterclockwise in the figure against the spring 9 together with the driven body 4. Further, the driven body 4 eventually comes into contact with the stopper 5 and cannot rotate any more. However, the wrapping material 7 continues to shrink while slipping on the pulley 2 and returns to the length of the memorized shape. .

Next, when the energization of the wrapping material 7 by the energizing device is stopped, the wrapping material 7 is cooled and again subjected to the extension deformation by the force of the spring 9. Therefore, the pulley 2 rotates in the clockwise direction in the figure together with the driven body 4. Then, the driven body 4 eventually comes into contact with the stopper 6 and cannot rotate any more. However, the wrapping material 7 is still stretched and deformed while slipping on the pulley 2 to a length that balances the force of the spring 9. to continue.

After that, every time the energization and the energization stop of the wrapping material 7 are repeated, the above operation is repeated.

Now, as long as the number of times of repeating the above-described stretch deformation-shape recovery operation of the wrapping material 7 is small, the length of the memorized shape of the wrapping material 7 is extended each time the operation is repeated.
The rotation range α of the pulley 2 changes accordingly.

However, in this device, the movable range of the driven body 4 is restricted to the constant range θ by the stoppers 5 and 6, so long as the rotation range α of the pulley 2 includes the range θ. The operating range of the driven body 4 is always the constant range θ.

Further, if the spring 9 is provided with a stroke sufficient to absorb the elongation of the wrapping material 7 caused by the repeated operation, the expansion / contraction stroke of the wrapping material 7 due to heating-cooling hardly changes.

Further, in this device, the driven body 4 is driven via the pulley 2 by the shape recovery force from the elongation deformation of the linear shape memory alloy, so that the driven body 4 can be driven at a high speed with a large force. it can.

In the above embodiment, the wrapping material 7 is made of only the shape memory alloy, and the shape memory alloy is wound around the pulley 2. However, the wrapping material 7 is linearly formed into a linear shape memory alloy. The non-shape memory alloy material may be connected in series, and the non-shape memory alloy material may be wound around the pulley 2.

Further, in the above embodiment, the shape memory alloy is heated by direct electric heating, but in the present invention, the shape memory alloy may be heated by another method.

〔The invention's effect〕

As described above, the thermo-dynamic energy converter according to the present invention operates the driven body driven by the shape memory alloy even if the operation range of the shape memory alloy changes due to the repeated deformation-shape recovery operation. Since the range is always the predetermined range, the device can always function normally, the structure is simple, and the excellent effect that the driven body can be driven at high speed with a large force can be obtained. is there.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a thermo-dynamic energy exchange device according to the present invention. 2 ... pulley, 4 ... driven body, 5, 6 ... stopper, 7 ... wrapping material, 9 ... tension coil spring.

Claims (1)

[Claims] 1. A rotatable pulley, a driven body which is mechanically linked to the pulley and moves in conjunction with the pulley, and a movable range of the driven body is restricted to a certain range. A wrapping material wound around the pulley, comprising a regulating means and a linear shape memory alloy alone, or a linear non-shape memory alloy material connected in series to the linear shape memory alloy. And a spring means that is connected to one end side of the wrapping material and that applies a tensile force to the shape memory alloy, and the torque transmitted from the wrapping material to the pulley reaches a predetermined magnitude. Then, the wrapping material slips with respect to the pulley, wherein the thermo-dynamic energy conversion device is characterized.