JPH09109320A - Shape recovery device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape recovery device having bidirectional shape recovery actions and good responsibility to temperature by laminating a shape memory composite composed of a shape memory allay having a specified shape recovery temperature and generation force and shape memory polymer having memory of a shape in different direction from the recovery action of the alloy, a Peltier element, a radiator in sequence. SOLUTION: In a shape recovery device, a shape memory composite 3, a Peltier element 4, and a radiator 5 are laminated in sequence. The shape memory composite 3 is composed of a shape memory alloy 1 having memory of a shape recovery action and a shape memory polymer 2 having memory of a shape recovery action in different direction from the recovery action of the alloy 1. The shape recovery temperature (martensite reverse modification temperature Af) of the alloy 1 is made higher than the shape recovery temperature (glass transition temperature Tg) of the polymer 2. Besides, a temperature at which (recovery stress × cross section) or the generation force of the alloy 1 is equal to (recovery stress × cross section) of the polymer 2 is set up to come between Af and the martensite modification temperature (Mf) of the alloy 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape memory composite having a bidirectional shape recovery operation and excellent in responsiveness to temperature.

[0002]

BACKGROUND OF THE INVENTION In recent years,
Drive devices using shape memory materials such as shape memory alloys (hereinafter referred to as SMA) and shape memory polymers (hereinafter referred to as SMP) are used as actuators of various machines and devices. These shape memory materials are often cooled by natural cooling, but in that case, the shape recovery operation takes time because of poor temperature response during cooling, and it is difficult to control the shape recovery operation. Therefore, there is a problem that the function as an actuator is extremely limited. In order to solve the above problem, a drive device using a Peltier element for heating and cooling the SMA has also been proposed (Japanese Patent Laid-Open No. 61-14770). However, the SMA and SMP shape recovering operations of the driving device using the Peltier element are unidirectional (irreversible) occurring in only one direction. Regarding SMA, it is possible to impart bidirectionality (reversibility) by subjecting it to special heat treatment or processing conditions, but the shape recovery force during heating and cooling is significantly different and deformation occurs once. It was difficult to restore the original shape. In other words, since it cannot return to the shape before recovery by itself, in order to operate it as a repetitive drive device, a component that acts to restore the shape before recovery is required, which is a problem in terms of downsizing and weight saving of the device. was there.

An object of the present invention is to solve the above problems, and to provide a shape recovery device having a shape recovery operation in two directions and excellent in responsiveness to temperature.

[0004]

SUMMARY OF THE INVENTION The present invention comprises (1) a shape memory alloy that remembers a certain shape recovery motion, and a shape memory polymer that stores a shape recovery motion in a direction different from that of the shape memory alloy. , The shape recovery temperature (martensite reverse transformation temperature, Af) of the shape memory alloy is higher than the shape recovery temperature (glass transition temperature, Tg) of the shape memory polymer,
The temperature at which the (recovery stress x cross-sectional area) of the shape memory alloy or the generated force becomes the same as the (recovery stress x cross-sectional area) of the shape memory polymer falls between Af and the martensitic transformation temperature (Mf) of the shape memory alloy. The shape memory polymer retains the shape remembered by the shape memory alloy's recovery operation to the memorized shape above the temperature, and the shape memory polymer is maintained at a temperature below the temperature and above the Tg of the shape memory polymer. The shape-recovering device is characterized in that the shape-memory polymer retains the memorized shape by the recovery operation to the memorized shape, (2) a Peltier element, and (3) a heat radiator are laminated in this order. It achieves the purpose.

The SMP used in the present invention is not particularly limited as long as it is usually used as SMP, and examples thereof include polyurethane, polynorbornene, polyisoprene, styrene-butadiene copolymer, etc., at the shape recovery temperature. Polyurethane is particularly preferable because a certain glass transition temperature (hereinafter referred to as Tg) can be arbitrarily set. Polyurethanes commonly used as SMP are block copolymers composed of polyols, diisocyanates, and chain extenders such as short chain glycols and amines, and the shape recovery temperature can be adjusted by changing the molar ratio of these constituents. Can be freely set from −30 ° C. to 60 ° C. In the present invention, Tg is JIS K
It is the value measured according to 7121.

The SMA used in the present invention is the martensite reverse transformation temperature (hereinafter referred to as A
It is called f. ) Is less than or equal to the SMP molding temperature (about 120 to 200 ° C.), and in particular, Af is S.
Ti-Ni-based SMA and copper-based SMA which are considerably lower than the molding temperature of MP are preferably used. Ti-Ni type SMA
Examples thereof include a Ti-Ni binary alloy, a Ti-Ni-Cu alloy, a Ti-Ni-Nb alloy, and a Ti-Ni-Fe alloy. These Ti-Ni-based SMAs have an Af of -10 ° C.
１００100 ° C. Also, as a copper-based SMA, Cu-Z
Examples include n-Al alloys and Cu-Al-Ni alloys, and the Af of these copper-based SMAs is -100 ° C to 100 ° C.

SMA has a martensite phase (hereinafter referred to as M phase) structure at a low temperature, and is a material that undergoes phase transformation to a matrix phase structure at a certain temperature or higher. The shape recovery effect utilizes this phase transformation. When the M-phase SMA is heated, transformation to the parent phase (martensite reverse transformation) gradually occurs,
Eventually, he becomes a perfect mother. Generally, the temperature at which this parent phase transformation ends is called the Af point, and this Af point is the shape recovery temperature of the shape memory alloy. On the contrary, when cooling from the temperature range of the matrix phase, the martensitic transformation gradually occurs and eventually becomes a complete M phase. The end temperature of the martensitic transformation is called the Mf point.

In the present invention, the above-mentioned SMA and SMP
It can be arbitrarily selected from and combined. However,
Since the SMP needs to be already softened when the shape of the SMA is recovered, it is necessary that the Af point of the SMA is higher than the Tg of the SMP. Further, when the temperature is lowered from the Af point, the SMA is not cured until the SMP is cured.
Since the shape recovery force of SMP must be larger than the shape recovery force of SMP, Tg of SMP must be lower than the Mf point of SMA. The difference in shape recovery temperature between SMA and SMP is not particularly limited, but considering practicality, Tg is preferably 10 ° C. or more lower than the Mf point, more preferably Tg is 20 to 40 ° C. or more lower than the Mf point. good. A preferred combination of SMA and SMP has a Tg of 2
Shape memory polyurethane of 0 ~ 40 ℃ and Af point of 50 ~
Ti-Ni SMA at 80 ° C and Mf point of 30 to 60 ° C,
In particular, a Ti-Ni binary alloy and a Ti-Ni-Cu based SMA can be mentioned.

As described above, the shape memory composite used in the present invention is SMA at high temperature (above Af point of SMA).
Keeps the shape that it remembered, but at low temperature (below the Mf point of SMA and above Tg of SMP), SMP must overcome the shape retention of softened SMA and make SMA follow its own shape. There is. Thus SMA and S
The balance of the shape recovery power of MP is the shape recovery power of SMA,
That is, (recovery stress x sectional area) or generated force and SMP
The temperature at which (recovery stress x cross-sectional area) becomes equal to SMA A
It can be set by setting between the f point and the Mf point. If the temperature is higher than the Af point, the SMA may not be in a state where the shape is sufficiently recovered during heating, and if the temperature is lower than the Mf point, the SMP may not be in a state where the shape is sufficiently recovered during cooling. However, it is not preferable because the displacement of the shape memory composite is reduced or the bidirectionality is lost.

In the present invention, when the SMA is processed into a coil shape, the shape recovery force is not (recovery stress × cross-sectional area), and in that case, the shape recovery force is referred to as a generating force. For example, Ti-Ni SMA coil (diameter of wire: 0.2 mm, coil outer diameter: 0.8 m
The generated force of m) is 50 to 70% of the amount of displacement of the coil and 0.2 to 0.3 kgf at the Af point. On the other hand, the recovery stress of the polyurethane SMP is about 0.2 to 0.3 kgf / mm ² at Tg for the same displacement amount as SMA. Therefore, the S when the SMA coil is covered with the SMP sheet
The cross-sectional area of MP may be about 1 mm ² . Thus, SM
When an element such as an A coil is coated with SMP, the generated force of SMA is obtained by calculation or measurement, and the temperature at which (recovery stress x sectional area) of SMP becomes equal to the generated force is the SMA Af point and Mf. The type of SMP and the thickness of the sheet may be determined so as to be between the points.

The shape memory composite used in the present invention is manufactured by the following various methods. First, SMA is processed into a plate shape, a wire material, a coil shape, etc., and then SMP is coated.
The shape of the SMA is not particularly limited, but it is preferable to process it in a coil shape from the viewpoint of the shape recovery force. Also, S
As the coating method of MP, there are a method of coating the surface of SMA with heat-melted SMP, a method of coating SMP dissolved in a solvent and drying, a method of extrusion coating SMP on SMA, a method of hot pressing, etc. Further, there is a method of covering the entire SMA with a sheet of SMP and hot pressing. Whichever method is adopted, since the SMP needs to store a shape different from that of the SMA, the SMA has a shape different from that which the SMA remembers before the SMP is covered. It is necessary to transform it into a shape that should be remembered. Further, when heat is applied to mold the SMP into a desired shape, heat of 400 ° C. or higher may cause SMA re-memory, so heat of preferably 300 ° C. or lower, more preferably 200 ° C. or lower. multiply.

The shape recovery device of the present invention comprises a shape memory composite body, a Peltier element and a heat sink laminated in this order. The heat absorption surface of the Peltier element cools the shape memory composite body, while the heat generation surface of the Peltier element is , Promote heat dissipation by the radiator. The Peltier element utilizes a phenomenon in which heat is generated or absorbed at the junction when a current is passed through the junction between two kinds of metals or semiconductors, and the heat absorption surface and the heat generation surface are reversed depending on the direction of the current flow. It is a thing.
The Peltier element used in the present invention is not particularly limited as long as it is usually used, but when cooling the shape memory composite, a current such that the heat absorption surface of the Peltier element is brought into contact with the shape memory composite. Need to be directional. At that time, the heat generating surface of the Peltier element is in contact with the heat radiator, and the heat radiator accelerates the heat radiation of the Peltier element.
The radiator used in the present invention is not particularly limited as long as it has a good thermal conductivity, and copper, silver, aluminum or the like may be used in a plate shape, a fin shape, a blade shape or the like.

In the present invention, it is preferable to fix one end of the shape memory composite to the Peltier element in order to effectively utilize the displacement amount of the shape memory composite. The fixing method is not particularly limited, and examples thereof include an adhesive and a wire. Further, in the present invention, it is preferable to fix both the Peltier element and the radiator. The fixing method is not particularly limited, and examples thereof include adhesive, wire, and soldering.

The shape memory composite is displaced by heating and cooling. In the present invention, the Peltier element is used for cooling. However, the method for heating the shape memory composite is not particularly limited, and conventional methods can be used. For example, heating with hot water, electric heating, heating by irradiation with heat rays such as laser, etc. may be mentioned. Further, the Peltier element used for cooling can be used for heating by changing the direction of current flow.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The shape recovering apparatus of the present invention is used for a blower wind direction deflecting flap drive mechanism of an air conditioner, an actuator for driving a bending mechanism of an endoscope such as a gastric camera or an industrial end scope, and a temperature of an electromagnetic cooker. It is applied to display actuators, valve switching actuators for automobile fuel evaporative emission control devices, pressure regulator actuators for siphon coffee makers, shutter opening / closing actuators for auto desiccator dry units, and damper switching actuators for fireproof dampers.

FIG. 1 shows an embodiment of the shape recovery device of the present invention. S of Ti-Ni binary alloy with a cross-sectional area of 1.0 mm ^2.
The MA wire (Af point: 80 ° C., Mf point: 50 ° C.) was heat-treated to memorize the bent shape as shown in FIG. This S
The MA wire was stretched into a linear state, and polyurethane SMP (Tg: 30 ° C.) was coated thereon to a thickness of 4.5 mm. The molding temperature is 200 ° C. After that, the shape memory composite, the Peltier element, and the radiator are laminated in this order,
One end of the shape memory composite was fixed to the Peltier device, and the Peltier device and the heat radiator were also fixed. When this linear shape memory composite was heated, it gradually began to deform at around 70 ° C., and at about 80 ° C. or higher, it became a bent shape almost memorized by SMA. When a current is passed through the Peltier element to cause the surface contacting the shape memory composite to absorb heat and the shape memory composite is cooled, the shape memory composite gradually begins to expand at around 60 ° C. Became the shape that I remembered. This operation was repeated 100 times,
Almost no decrease in displacement was observed.

FIG. 2 shows another embodiment of the shape recovery device of the present invention. SMA wire rod of Ti-Ni-Cu alloy with a cross-sectional area of 0.3 mm ² (Af point: 70 ° C, Mf point: 58 ° C)
Was subjected to shape memory heat treatment in a state where the coil was a roughly wound coil having an outer diameter of 1.2 mm. Compress this coil (close winding)
Then, in that state, the polyurethane-based SMP (T
A sheet (g: 40 ° C.) (thickness: 0.2 mm) was wound into a cylindrical shape as shown in FIG. 2, heated and covered with this shape. The molding temperature is 200 ° C. After that, the shape memory composite, the Peltier element, and the radiator were laminated in this order, one end of the shape memory composite was fixed to the Peltier element, and the Peltier element and the radiator were also fixed. When the shape memory composite in this state was heated, when heated to 70 ° C., the shape memory composite expanded due to the shape recovery of the SMA coil. When a current is passed through the Peltier element to cause the surface contacting the shape memory composite to absorb heat and the shape memory composite is cooled, the temperature of the shape memory composite gradually decreases and begins to contract. The shape was memorized by SMP at around 0 ° C, and this shape was maintained even if the temperature was continuously lowered thereafter. This operation 10
Repeated 0 times, but almost no decrease in displacement was observed.

[0018]

The shape recovery device of the present invention comprises (1) a shape memory alloy that stores a certain shape recovery operation, and a shape memory polymer that stores a shape recovery operation in a direction different from that of the shape memory alloy. The shape recovery temperature (martensite reverse transformation temperature, Af) of the memory alloy is higher than the shape recovery temperature (glass transition temperature, Tg) of the shape memory polymer, and the (recovery stress x cross-sectional area) or generated force of the shape memory alloy is shape memory. The temperature at which the (recovery stress x cross-sectional area) of the polymer is the same as that of Af and the martensitic transformation temperature (M
f), the shape memory alloy retains the shape remembered by the shape memory alloy's recovery operation to the remembered shape above the temperature, and is below the temperature and above the Tg of the shape memory polymer. At the temperature of 2, the shape memory polymer retains the memorized shape by the recovery operation of the shape memory polymer to the memorized shape, (2) the Peltier element, and (3) the radiator is laminated in this order, It is directional and has excellent temperature responsiveness. Therefore, since a member for returning to the original shape is not required, the size and weight of the element can be reduced, and the shape recovery operation at the time of cooling becomes faster, so that the memory blur of the shape memory composite can be prevented. ,
Can withstand repeated use. In addition, since the shape recovery operation during cooling is also easily controlled, the function as an actuator is improved. Further, by using SMP as a polymer selected from polyurethane, polynorbornene, polyisoprene, and styrene-butadiene copolymer, it becomes easy to set the shape recovery temperature. In addition, SMA is Ti-
By using Ni-based SMA or copper-based SMA,
Since the f-point is considerably lower than the molding temperature of SMP, the shape memory composite is easily manufactured. Furthermore, by coating SMA with SMP, it has excellent corrosion resistance and insulation,
Wide range of applications such as medical applications. Further, by surrounding the outer circumference of the SMA coil with SMP, it is possible to obtain a shape recovery device having a better shape recovery force.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a shape recovery device of the present invention.

FIG. 2 is a view showing another embodiment of the shape recovery device of the invention.

[Explanation of symbols]

 1: Shape memory alloy 2: Shape memory polymer 3: Shape memory composite 4: Peltier element 5: Heat radiator

Claims (5)

[Claims] 1. A shape memory alloy that stores a shape recovery motion, and a shape memory polymer that stores a shape recovery motion in a direction different from the recovery motion of the shape memory alloy.
The shape memory alloy has a shape recovery temperature (martensite reverse transformation temperature, Af) higher than the shape memory polymer's shape recovery temperature (glass transition temperature, Tg), and the shape memory alloy's (recovery stress x cross-sectional area) or generated force is a shape. The temperature at which (recovery stress x cross-sectional area) of the memory polymer is set to be between Af and the martensitic transformation temperature (Mf) of the shape memory alloy, and above that temperature, the shape remembered by the shape memory alloy is set. The shape remembered by the shape memory alloy by the recovery operation to the shape memory polymer, and the shape remembered by the shape memory polymer by the recovery operation of the shape memory polymer at the temperature below the temperature and above the Tg of the shape memory polymer. A shape recovery device comprising: a shape memory composite for maintaining the above; (2) a Peltier element; and (3) a heat radiator laminated in this order. 2. The shape recovery device according to claim 1, wherein the shape memory polymer is a polymer selected from polyurethane, polynorbornene, polyisoprene, and styrene-butadiene copolymer. 3. The shape recovery device according to claim 1, wherein the shape memory alloy is a Ti—Ni-based shape memory alloy or a copper-based shape memory alloy. 4. The shape recovery device according to claim 1, wherein the shape memory composite is formed by coating a shape memory alloy with a shape memory polymer. 5. The shape memory composite comprises a shape memory alloy coil surrounded by a shape memory polymer.
The shape recovery device according to any one of claims.