JPS60208440A - Thermosensitive device - Google Patents

Abstract

PURPOSE:To provide a thermosensitive device which has an extremely small hysteresis range and good repetitive service life characteristics by forming an NiTi shape memory alloy in such a way that the two-way motion combined with bias load is the displacement to change the crystal structure of the alloy from a cubic crystal to a rhombohedral crystal when cool and is the displacement reverse thereto when heated. CONSTITUTION:This invention is obtd. as a result of studying the relation between the hysteresis and service life of the two-way motion of a shape memory alloy (MSA) consisting of an NiTi alloy system. More specifically, the two-way motion combining bias load with said MSA is made into the displacement by the transformation of the crystal structure of said MSA changing from a cubic crystal (B2 phase) to a penta-rhombohedral crystal (R phase) when cool and to the displacement by the transformation restoring the B2 phase from the R phase when heated. The provision of the intended thermosensitive device of which the hysteresis of the two-way direction is <=3 deg.C and the change of the working temp. and permanent set in fatigue are considerably decreased in the repetitive service life is made possible by the above-mentioned limitation of the motion.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of Application No. 141I relates to a heat sensitive device using a shape memory alloy.

1 Traditional configurations and their problems In recent years, shape memory alloys (hereinafter referred to as SMA)
(abbreviation for memory alloy))
, Month 1 (1') is actively researched.Many A and gold are known as SMA, but currently, in practical terms, Cu Z
n A I j7 gold and N i T i jl gold are used.

Considering the application to a heat-sensitive device, the KSMA during heating and cooling is 11], and the deformation temperature during heating and the deformation height during cooling are inversely deformed. , the difference from 1 degree (so-called hysteresis) is small, and further heating,
It is desired that there is less deterioration in life due to repeated cooling. Gold - Although it is a unidirectional SMA that deforms only when heated, the alloy's thermal properties are extremely superior to Cu alloys in terms of fatigue life.

For this reason, in α, China, and Germany, N1Tit''r minute, which only shows one-time i'L Ot work, is used -4 direction 0J work VC-L heaven.For example, as shown in Figure 1, A configuration is known in which a coil wire 1 made of N i Ti alloy wire treated with a shape 512 is made in a heated and tightly wrapped ambush, and a heavy bell 2 is hung from this. At temperatures below 1iNiTib gold's tensile strength coefficient and yield strength are low, and due to IR heavy ironing, the airfoil shape due to S force and σ-induced martensite deformation occurs, resulting in NiTiα gold coils. When the spring 1rI'i is stretched or fully heated, a large double bending force is generated that tries to fit the shape of the spring due to the shape memory effect at the production temperature, and the coil spring 1 of the NiTi Shimagane wire contracts and becomes heavy #! l!2 is raised.
The coil spring 1 made of Ti alloy wire is elongated, and the coil spring 1 is made of T i alloy wire. Then, it shrinks and moves in 11 directions within the 03 working range.

Among these, the force that causes movement, which is the opposite of the shape memory effect, as shown in #ll [2] can also be used as the force of a coil made of a normal spring material. many.

Kakaru, SMAK Tunshin (・jIIlliK Coil Gene Burning's counterattack)'s 11: I Heavy Metal Group G Seta One Direction m
In Nosaku's heat sensitive device, '', 1, the relationship between temperature T and friendly position S (SMA's fruit) is as shown in the 21'X, ζ, and the operating temperature during heating and cooling ω1 The so-called hysteresis phenomenon occurs due to the operating temperature6.
In all the heat sensitive devices used, the hysteresis temperature +1JΔT was 10 to 30'C.There was also the problem that the operating temperature decreased due to repeated use.During such hysteresis, the For use as a heat sensitive device to control temperature or move objects.
N i T i with good repeat life characteristics.
e:・This was a major hindrance to the industrial application of gold.

OBJECTS OF THE INVENTION The present invention is intended to solve these problems, and its primary purpose is to provide a heat sensitive device with extremely small hysteresis IIJ and good repeated life characteristics.

Structure of the Invention Undiscovered 1 was made as a result of extensive testing of the relationship between the alloy transformer and the hysteresis and life of the two-way U operation for the two-way operation of the SMA of N I T l & gold thread. Yes, there is a combination of bias loading and directional influence,
During cooling, the crystal structure of the alloy changes from a cubic crystal to a rhombohedral crystal structure, and when heated, the crystal structure changes from a rhombohedral crystal structure back to a cubic crystal structure.

Due to this limitation in the 01 work, it is possible to reduce the hysteresis of the two-way operation to 3C or more, and to minimize the repetition life (by setting υ to +f+, the dAIJ work 11, 1 degree y change and heta 9. Becomes Noh.

NiTi Itonekin is Hen 1 Island d111 degree and above, ;iigiI
II is a B2 phase and a 11f 7) square crystal, and when it is cooled, it directly changes to 11q W, Ill at iS degrees.
There are two known types: one in which the martensitic phase (M phase) of an orthorhic crystal is formed, and the other in which the martensitic phase of the 41 products is changed to a rhombohedral phase (7!i: ^). 1. Here, the rhombohedral crystals are generally called R phase.They have an electrical resistance of 11111 for the unstressed h-phase.
1.1 and X-ray diffraction (11r is observed, but the two directions dl in the stressed state) 4'l have no effect on 1.1 or 1e. And, the eclipse that changes from cubic crystal to diamond 1111G product during cooling is R
On the other hand, a metamorphosis that changes from a diamond-faced one-point product to a one-sided crystal when heated is called a reverse R-henten.

Explanation of Examples” Hereinafter, the unfired uiJ will be explained with reference to its examples.

, tlt: Ft is N i T i fJ gold, N i
A T i Cu alloy and a NiTiFe alloy having a hexagonal gold composition and an operating temperature (variable temperature) of 20 to 40° C. were used. (The uJ production temperature is affected by the 6-karat gold composition as well as the heat treatment and the weight of the alloy).

ViNiTiu gold will be shown below as a representative example.

A wire rod with a diameter of 0.75 J11 was used as a raw material, and this wire rod was wound into a tight coil shape with an average coil diameter of 5.6 mm and subjected to shape memory treatment. Shape memory processing Vi450 ”C ~ 550°
I went between C.

79412 in FIG. 1 for such an SMA coil spring.
Using a method using a 411 weight as a weight, various types of 7 weights were heated and cooled, and the temperature and deflection of the SMA coil spring were investigated for openness. Note that the bias load was converted into shear stress, and the deflection was converted into shear strain.

FIG. 3 shows the correspondence between typical operating hysteresis curves and electrical resistance measurements. This is 475°C, t! This is an example of bias load 6 and 9/mrAO in memory processing. From this relationship, ω
Singular points RMs, RMf, M on the Nosaku hysteresis curve
! l, RA s, RA f and AI are the electric resistance curves M s', M iI, Ms, As', Al, respectively.
1 and AIVC corresponds to the change in the electrical resistance curve of 1° caused by f4jL force 1lJL' (Vi stress applied -)
The following is the first thing we know when we investigate fundamental filf in a situation where it is not.

During cooling, Ms'Mf' and R values are expressed, and the electrical resistance trade region is the R range, and the point where the resistance decreases is the starting point of the interfloor transition to the martensitic phase. Occasionally, reverse R deformation occurs at As' and A I', and the transition to the high temperature B2 phase occurs at the Af point.

In this way, it has become clear for the first time that the singular point in the operating hysteresis curve of all combinations of bias loads is related to the tone metal domain.

r, B2 phase, R phase and M for samples subjected to various memory heat treatments.
Figure 4 is obtained by lowering the phase rf (Ef8).The phase rf (firJ M is up to the bias force corresponding to the maximum shear center force of τR. And τR is the shape notation 1
゜ω Treatment condition (!1), and the relationship is shown in Figure 5. 525C
When it exceeds i, the R phase almost no longer exists.

As described above, in the -1 direction ω] production in which N i T i fj gold-cocoil wire is combined with a bias load and set to D, B
The shear core temperature phase diagrams of 2-phase, R-phase and M-kan are I-J.
It became a big deal.

Therefore, we next examined the relationship between the two-way σσ cropping characteristics and the variation. Condition (2) for the present invention is a combination of a bias load that makes the shear core force less than τR, and a minimum cooling temperature (1-R phase existing region, when heating and cooling of R phase-B2 phase is repeated). A certain condition 111″t shear center force is rR
Bias load below? Set G, minimum cooling temperature f
M s will-cutting M (as the area where 11 is born,
For M, when heating and cooling of the X, R, and B2 phases are repeated, another conventional example, condition (2), is a combination of bias loads that result in a shear center force of 18 or more, and M411 = B2.
This is where the phases are repeatedly heated and cooled.

FIG. 6 shows the difference in hysteresis curves due to repeated heating and cooling under these three conditions. In condition ■, the extremely small 3°
A hysteresis of C or less was obtained.

In addition, changes in operating temperature due to repeated heating and cooling are
As shown in the figure. Condition 1 is operation 111 (1 degree change is extremely small.Furthermore, the change in shear strain applied at high temperature (B2 phase) per 1 turn (settling) is shown in Figure 8, and this cow 4 sex change Condition I is also the smallest.

Hereinafter, let's take the theory 1 -N r T 10 * as an example.)
However, Ni Ti Cu i'i gold and NiTiF
Exactly the same results were obtained for eα gold.

In order to obtain condition I to become Ki-ni 1Jll, use -14
The shear center force and the minimum 11 n'r degree are the R-phase feed M in Figure 4.
, Vc<. As long as this condition is met, the shape of the NiTi thread may be a coil spring, a simple wire, or a plate. As for the heat treatment, does the temperature differ depending on the metal thread?
(The heat treatment conditions should be such that the 1irJ region of 11 is formed3). Only your shop between the phase and the R phase (it is produced as L-01, as a result, the hysteresis is extremely small, and the change and settling of the operating temperature due to repeated heating and cooling are extremely small) .

For this reason, various control devices that were difficult to control in the past due to accuracy, such as temperature setting devices for constant temperature baths, thermal valves for fluid paths,
Air conditioner's wind direction changing mechanism, Roboso which requires long life]・
The application to various actuators including all types of actuators is suitable for IJIF, and provides excellent effects as a heat sensitive device.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a two-way thermal sensing device that combines shape-memory gold and bias loading. Figure 2 is a diagram of the relationship between temperature and displacement (hysteresis curve) to explain the operation of a two-directional thermal sensing device. , Fig. 3 is a relational diagram showing the correspondence between the actual hysteresis curve and electrical resistance change in the operation in the mouth direction O, and Fig. 4 shows the normal 1M (B 2 phase, R
phase and M phase), shear core temperature phase diagram, Fig. 5ViR
A diagram showing the amnestic temperature dependence of the maximum value τR of the shear core force in the region where the phase exists, FIG. 6 is a comparison diagram of the hysteresis curve with a conventional example showing the effect of the present invention, and FIG. 7 is a diagram showing the effect of the present invention. FIG. 8 is an operating humidity life characteristic diagram showing the effect of 1, and FIG. 1... Shape memory 6 gold coil spring, 2...
- Weight ((Bino'suili engineering i1j), Mr. N's deputy + Pruri [: Toshio Nakao and 1 others)
Figure 1. Fig. 1 Skin (1C) Fig. 4 Fig. 5 实银采社/1 6 Fig. 7 Fig. 8 Factor P

Claims (2)

[Claims] (1) A NiTi-based shape memory alloy is configured to operate in one direction by applying a bias 111f to the crystal structure of the alloy, which changes from cubic (B2 phase) to rhombic ( Thermal sensitive device i is defined as the displacement due to y changing to the R phase), and the displacement due to the change 1 island passing from the R phase to the B2 phase during heating.
710 (2) NiTi-based shape memory alloy has a shape memory effect. NiTi alloy, NiT1Cu1 gold or iJ:NiTi
The heating core device according to item 1 of the special J.