JPH0275773A - Tehrmally-driven engine - Google Patents

Abstract

PURPOSE:To enable the generation of a power with high efficiency by a method wherein by utilizing a difference in a force between a force by means of which deformation is created at a low temperature phase and a shape memory restoring force by means of which restoration to a state before deformation after martensite reverse transformation is created, a memory belt circulating between a cold water tank and a hot water tank is used. CONSTITUTION:A memory belt 1 made of a shape memory alloy cooled in a cold water tank 7 for stretch enters a water tank 6 at a point (a) to gradually increase temperature. When temperature is increased to some value, martensite transformation occurs, and a shape memory restoration stress is generated. When the shape restoration stress exceeds a given force, length is shortened at points (e) - (f) and a shape is restored, tension between points (d) - (h), and the memory belt 1 is moved in the direction of an arrow mark. The belt enters the cold water tank from a point (j) for cooling, martensite transformation occurs at a point (k) and is stretched between points (k) - (o). The memory belt 1 enters the hot water tank 6 from the point (a) again and is continuously moved. The above movement is taken out as a rotation force from a shaft 8.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention converts low-grade thermal energy such as geothermal heat, heated waste water, solar heat, etc., which has a relatively low utility value, into mechanical energy and aims to utilize energy effectively. A heat-driven engine that can do a lot of things.

(Prior art) As shown in Fig. 6, two pulleys of different diameters 100°101
A memory belt 104 made of a shape memory alloy formed in a loop shape is hung over the pulleys 102 and 1 of the same diameter.
03 are fixed to pulleys 100 and 101, respectively, and a normal belt 105 is hung thereon.

By heating part A and cooling part B, the pulley 100.
A thermally driven engine in which 101 rotates is considered,
Due to the structure, the hot water tank and cold water tank that heat and cool the memory belt 104 are dish-shaped and have a small heat capacity, so the temperature of the hot water and cold water is not stable.Furthermore, the tensile force of the high temperature phase of the memory belt 104 is exerted on the low temperature phase. Since the life of the memory belt 104 is shortened due to excessive stress, the magnitude of high temperature phase stress is limited, and large power cannot be extracted to the outside.

(Example) When a force is applied to a metal called a shape memory alloy while it is in a low-temperature phase (martensitic phase) below its transformation temperature, it undergoes apparent plastic deformation, but when heated, it undergoes a high-temperature alloy (austenite phase).
If you do this, it will return to its pre-transformed state. The transformation from a low-temperature phase to a high-temperature phase is called martensitic reverse transformation, and the transformation from a high-temperature phase to a low-temperature phase is called martensitic transformation. Since the returning shape memory recovery force is greater, power is obtained by utilizing the difference in force. In FIG. 1, pulley 4 and pulley 3 are wedged to shaft 9 and shaft 8, and pulley 5
is an idler and is located in cold water tank 7. Pulley 2
is in the hot water tank 6, and the pulleys 2, 3, 4, 5
All diameters are the same. Sprocket 11 is fixed to pulley 2, and sprocket 12 is fixed to pulley 3. Sprocket 11 and sprocket 12 have the same diameter and are connected by chain 13. Sprocket 14 is for tensioning chain 13. All the pulleys except pulley 5 are connected by conduction mi, and the rotation direction is that pulley 3 rotates clockwise and pulley 4. Pulley 2 is designed to rotate counterclockwise. By the deceleration tl110, the shaft 9 rotates in the opposite direction to the shaft 8 and is decelerated to a deceleration ratio of 1, and i can be changed manually or automatically. Memory belt 1 made of shape memory alloy, cooled and stretched in a cold water tank 7
enters the hot water tank 6 from point A and gradually heats up, and when it reaches a certain temperature, martensite reverse transformation occurs at the point A, the elastic modulus increases to 2, and shape memory recovery stress is generated. The shape recovery stress increases as the temperature rises, and when it exceeds the sum of the stress of the force taken out from the shaft 8 and the stress for stretching the memory belt 1 in the low temperature phase, the length decreases and shape memory recovery occurs. The tension between points 2 and 1000 increases between pulley 4 and pulley 2.
The storage belt l moves in the direction of the arrow and reaches the cold water tank 7.
It enters from point N and is cooled, undergoes martensitic transformation at point L, its elastic modulus decreases, and is stretched between point L and point Y. The memory belt 1 enters the hot water tank 6 again from point A and continues to move continuously. To explain the movement of the memory belt 1 and the pulleys, in Fig. 1, the memory belt 1 recovers its shape memory between points HO and 100, and the memory belt 1 contracts, and the tension between points 2 and 1000 increases, and the pulley 4 attempts to rotate clockwise, and tries to rotate pulley 2 counterclockwise. Now, let the pulley 4 side of the tension of the memory belt 1 be Fl, and the pulley 2 side be F2, and the pulley 4.
If the radius of 2 is R, the reduction ratio of pulley 4 to pulley 3 is i, and 1 clockwise rotation is 10 and counterclockwise rotation is -, then pulley 2 and pulley 3 are sprockets 11 and 12.
, the chain 13 rotates in the opposite direction and at the same rotational speed, so the moment M1 that tries to rotate the shaft 8 at Fl is M, = FIRi X (-1) = -FIRi
The moment M, which tries to rotate the shaft 8 at F, is Mx = (FIR) ,R
So M, <M! Therefore, the shaft 8 rotates clockwise and the storage belt 1 is fed in the direction of the arrow. Also, to explain the relationship between the shape memory recovery amount and speed of the memory belt 1, V is the moving speed of the memory belt 1 in the low temperature phase, and 2 is the moving speed of the memory belt 1 in the high temperature phase.
If the moving speed and reduction ratio are i, and the amount of shape memory recovery per unit time is S, then V = iV, ......■ S = V, -V, ......■ Substituting equation 0 into equation 0 and sorting it out, V+=S/(1-i) Vx=S/l(1/i) 11 If expressed graphically, it will be shown in Figure 2, and the larger the number of subscripts of i, the slower the speed will be. If the reduction ratio i, which indicates that the ratio is small, is constant, then v
l, ■2 indicates that it increases as S increases, and S
Assuming that is the same, the smaller the reduction ratio, the larger ■1 and ■ become.

Figure 3 shows the relationship between the temperature and shape memory recovery stress of the memory belt 1 that has undergone reverse martensitic transformation. Figure 4 shows that the larger the subscript, the greater the amount of strain applied at low temperature, and the maximum value of shape memory recovery stress increases depending on the amount of strain applied at low temperature. indicates the relationship between stress and strain in the memory belt 1, the α curve indicates the relationship gA between strain and stress in the low temperature phase (martensite phase), and the β curve indicates the relationship between strain and stress in the high temperature phase (austenite phase) σ2 is the sum of the stress σ1 that stretches the memory belt l in the low temperature phase and the stress for the power taken out from the shaft 8. The katakana shown in Figure 0 corresponds to the position of the memory belt 1 shown in katakana in Figure 1. The memory belt 1, which has been cooled and stretched in the water tank 7, enters the hot water tank 6 from point A and is heated.When it reaches a certain temperature, it reversely transforms into martensite at the mouth, and further increases stress as the temperature rises, and reaches point E. σ
When reaching , the shape memory recovers and the strain decreases to ε, reaching the point.The recovery force causes the pulley 4.2 to rotate and the memory belt 1 is sent from point N to the cold water tank 7 where the temperature is gradually lowered. At point L, martensitic transformation occurs, the elastic modulus and stress decrease, and when the stress becomes σ1, it is stretched until the strain becomes ε2, reaching point Y. The water is then sent sequentially and enters the hot water tank 6 from point A. A major factor that determines the lifespan of shape memory alloys is excessive stress in the low-temperature phase, and in order to prevent this, it is necessary to maintain the position of the tip in Figure 1 in a fixed position.

This is because as the distance from the mouth of the tiger to point Ha increases, the temperature of the mouth of the tiger remains constant, so the temperature at the point increases and the average stress from the mouth of the tiger to point Ha also increases, and eventually the stress from the mouth of the tiger to point Ha also increases, so the stress in the low temperature phase becomes excessive. Also, when the tiger mouth passes the point and approaches point 2, the difference in tension of the memory belt between point C and between point 2 and point C cannot be received by pulley 2, resulting in excessive stress being applied to the low temperature phase at point 6. The causes of misalignment of the openings include temperature changes in the cold water tank 7 and hot water tank 6 and fluctuations in the torque taken out to the outside. As the heating time changes, the degree of martensite reverse transformation shifts. Also, if there is a change in the torque taken out to the outside, the shape memory recovery stress shown in Figure 3 is proportional to the temperature, so if the torque taken out to the outside is small, the shape memory recovery will be faster, and if the torque taken out to the outside is large, the shape memory recovery will be. Since it slows down, the length after shape recovery changes, and since the total length of memory belt 1 is constant, the amount of strain in the low temperature phase changes, and the amount of shape memory recovery changes, so the speed of memory belt 1 changes, and the position of the tiger mouth changes. . Therefore, as a method of keeping the position of the tiger mouth constant, the speed reduction ratio l of the reducer 10 is changed to change the speed of the memory belt 1. As shown in Fig. 2, when the amount of shape memory recovery is constant, by changing the gear ratio i of the reducer 10, V,, V, can be changed and the 8 positions of the tiger mouth can be kept constant, and the excessive You can avoid stress. The position where martensitic reverse transformation occurs (the first stage) is determined when there is no excessive stress applied to the low temperature phase, such as when the stress in the high temperature phase of the memory belt 1 is small, or when there is a method to alleviate the excessive stress applied to the low temperature phase. If excessive stress is not applied to the low-temperature phase even if the position (see Figure 1) is shifted, the reducer 10 can be used to improve efficiency. When the shape memory recovery force is constant, the faster the speed of the memory belt 1 is, the more M11! 'The power output by the storage belt 1 increases and the efficiency also increases. Point H of shape memory recovery amount 1 in Figure 1
As the speed of the memory belt 1 increases, the memory belt 1 approaches the point where it exits the hot water tank 6, and the closer it gets, the more efficient it becomes.By changing the reduction ratio i of the reducer 10, thermal energy is converted into mechanical energy. Conversion efficiency can be improved.

FIG. 5 shows an embodiment for alleviating excessive stress in the low temperature phase. Several pulleys 15 are installed between the pulleys 2 and 3, and a sprocket 16 is fixed to each pulley 15, and the pulley 15 is driven by a chain 13 so that it has the same rotational direction and the same circumferential speed as the pulley 2. Therefore, the tension of the high temperature phase is not received by the pulley 15 even if the distance between the point of contact between the tiger mouth at the martensitic reverse transformation position and the point of contact between 1 and 2 becomes longer. This is an example in which excessive stress is not applied to the low temperature phase.

(Effect of the invention) By installing pulleys in the cold water tank and the hot water tank, the length of the memory belt in the water tank can be increased, and the storage belt can be sufficiently heated and cooled in a water tank with a large heat capacity, so that the temperature of the water tank can be lowered. Because it is stable, stable power can be extracted. Furthermore, by controlling the speed of the memory belt using a speed reducer, excessive stress on the memory belt can be prevented and efficiency can be improved.

[Brief explanation of the drawing]

Fig. 1 is a side view and structural explanatory diagram of an embodiment of the thermally driven engine of the present invention, and Fig. 2 is a speed diagram of the storage belt 1 entering the hot water tank 6 (low temperature phase) or exiting the hot water tank 6 (high temperature phase). Phase) A diagram showing the relationship between the speed v2, the shape memory recovery amount S, and the reduction ratio i of the reducer 10, FIG. 3 is a diagram showing the relationship between the temperature of the memory belt 1 and the shape memory recovery stress, and FIG. A diagram showing the relationship between strain and stress in the memory belt 1, FIG. 5 is an embodiment of the present invention for alleviating excessive stress in the low temperature phase, and FIG. 6 is a diagram showing the conventional thermally driven engine 1 memory belt 2 pulley 3 pulley 4 pulley 5 Pulley 6 Hot water tank 7 Cold water Wj S shaft

Claims (1)

[Claims] A memory belt 1 made of shape memory alloy is hung on four pulleys 2, 3, 4, and 5, and pulley 5 is an idler and is placed in cold water in a cold water tank 7, and pulley 2 is placed in hot water in a hot water tank 6. The pulleys 3 and 4 are wedged on shafts 8 and 9, respectively, shaft 8 is a transmission shaft for the output taken out to the outside, and shaft 9
is decelerated by a reducer 10 relative to the shaft 8 and rotates in the opposite direction, and the reducer 1 is automatically or manually rotated in response to output torque fluctuations, temperature changes in the cold water tank 7 and the hot water tank 6, etc.
0 reduction ratio can be changed, sprocket 11,
12 is fixed to pulleys 2 and 3, respectively, and chain 1
3, the pulley 3 is connected to the pulley 2 so that it rotates in the opposite direction at the same rotational speed, and the sprocket 14 is for tensioning the chain 13. This heat-driven engine allows installation of several pulleys 15 having the same circumferential speed and several sprockets 16 fixed to the pulleys 15.