JP2003148534A - Spring constant variable type spring and stirling engine with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spring constant variable type spring easily changing a spring constant and capable of finely adjusting the spring constant after assembling it into an object material. SOLUTION: This spring constant variable type spring 10 is characterized in that multiple elastic base material formed into a spiral shape with a prescribed width and the thickness from a minimum-diameter inner end 11 to a maximum-diameter outer end 11b are assembled in such a disposition that the mutual surfaces in the thickness direction are spirally opposed to one another.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spring constant variable spring and a Stirling engine including the spring.

[0002]

2. Description of the Related Art Generally, a Stirling refrigerator uses a thermodynamic cycle known as a reverse Stirling cycle, and obtains cryogenic cold heat by reciprocating a displacer and a piston with a predetermined phase difference. In this Stirling refrigerator, in order to reduce the vibration during the reciprocating motion of the displacer and the piston, it is required to minimize the shake in the direction perpendicular to the reciprocating direction of the displacer and the piston.

Therefore, for example, Japanese Patent Laid-Open No. 5-288419.
As disclosed in the publication, a leaf spring elastically supporting a compressor in a compressor so as to reciprocate in its axial direction and immovably in a direction (radial direction of piston) perpendicular to the reciprocating direction of the piston. By use, it is known to reduce the vibration of its piston.

That is, since this leaf spring has a high rigidity in the radial direction of the piston and is hardly deformed in that direction, the radial deviation of the piston is reduced and the vibration of the piston is reduced, while the axial direction of the piston is reduced. Since the elastic deformation is large, the vibration of the piston during reciprocating motion can be reduced.

Further, as disclosed in Japanese Patent Application Laid-Open No. 10-325629, a spiral shape is formed by removing unnecessary portions by heat such as laser processing between the central portion and the outer peripheral edge portion of the leaf spring. It is known that the above-mentioned function can be obtained even if the slit hole is formed, but they are common in that they are manufactured by cutting out one plate.

[0006]

These leaf springs are supposed to be attached to an object (for example, a Stirling engine) for use. Therefore, it is important that the attached leaf spring does not deviate from the predetermined spring constant in order to ensure stable performance when the Stirling engine is operated.

However, with the above-described processing method, it is not possible for the leaf spring itself to correct the deviation of the spring constant caused by the variation in spring constant during mass production of the leaf spring and the dimensional tolerance of the mounting position on the object. Furthermore, even if it is a part, if the leaf spring is damaged, the leaf spring itself must be replaced.

The present invention has been made in view of the above conventional problems, and the spring constant can be easily changed, and the spring constant can be finely adjusted after the spring constant is assembled to an object. The purpose is to provide a spring. Another object of the present invention is to provide a Stirling engine that can obtain stable performance by including such a spring.

[0009]

In order to achieve the above object, a spring constant variable spring of the present invention comprises an elastic base material having a predetermined width and thickness from an inner end having a minimum diameter to an outer end having a maximum diameter. It is characterized in that a plurality of them are combined in an arrangement such that their surfaces in the thickness direction face each other. Therefore, by selecting the number according to the elastic force of the elastic base material, a constant spring constant can be realized as the whole spring constant variable spring. That is, the number of elastic base materials required to obtain a constant spring constant can be changed.

Further, according to the spring constant variable spring of the present invention, the spring constant can be gradually increased by cutting the elastic base material by a predetermined length from the outer end of the maximum diameter of the elastic base material. Therefore, it can be changed to an arbitrary spring constant.

In the spring constant variable spring of the present invention, a screw hole penetrating in the thickness direction is provided at the inner end or the outer end of the elastic base material so that a screw is inserted within the range. Fine adjustment of the spring constant is possible.

By integrating the inner end portion of the elastic base material with a disk, the center portion of the spring can be securely fixed without being displaced in the radial direction. Furthermore, by integrating the outer end portion of the elastic base material with the ring-shaped holding member, the outer peripheral portion of the spring can be securely fixed without being displaced in the radial direction. In that case, a donut-shaped washer with a rounded edge may be sandwiched between the disk and the elastic base material, and a flat washer with a rounded edge may be sandwiched between the ring-shaped holding member and the elastic base material. .

According to the present invention, in a Stirling engine having a piston and a displacer which reciprocate in the same direction in a cylinder with a predetermined phase difference, the variable spring constant spring described above is provided as a piston spring and a displacer spring. Characterize. According to this, after assembling the piston spring and the displacer spring to the Stirling engine, the spring constants thereof can be adjusted as designed while performing an operation test.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 2 is a plan view showing a spring constant variable spring (hereinafter, simply referred to as “spring”) of the present invention. Spring 1
0 is a combination of three elastic base materials 11 arranged such that their surfaces in the thickness direction face each other in a spiral shape.

FIG. 3 is a plan view of the elastic base material. The elastic base material 11 includes an inner end 11a having the smallest diameter and an outer end 11b having the largest diameter.
It is formed in a spiral shape with a predetermined width and thickness. The length from the inner end 11a to the outer end 11b is selected to have a predetermined dimension. Furthermore, the inner end 11a and the outer end 11
A screw hole 16 penetrating in the thickness direction is provided near b. By designing the width, thickness, and length of the elastic base material 11, a desired spring constant can be obtained for each elastic base material 11, and by combining a plurality of them, a necessary spring constant can be obtained as a whole. become. For example, when the spring constant is 100 N / m, the elastic force per elastic base material is 50 N / m, 2 and 25 N / m, 4 and so on.

As shown in FIG. 5, the elastic base materials 11 are spirally arranged so that the inner ends 11a of the three elastic base materials 11 are arranged in the circumferential direction at a central angle of 120 °, and the inner ends 1 thereof are arranged.
The central portion near 1a is sandwiched between the disc-shaped inner teeth 14 from above and below. At this time, the screw holes 15 of the inner teeth 14 and the elastic substrate 1
The screw holes 16 of the inner end 11a of No. 1 are aligned with each other. Then, the central portions of the three elastic base materials 11 are connected together with the inner teeth 14 by screws 17. This can prevent the center portion of the elastic base material 11 from being displaced in the radial direction. As shown in FIG. 4, by cutting the elastic base material 11 from the outer end 11b of the elastic base material 11 by a predetermined length, the spring constant of the spring 10 can be increased to an arbitrary value.

Next, as shown in FIG. 6, the outer ends 11b of the three elastic base materials 11 are sandwiched by the two outer peripheral holding rings 18 from above and below. At this time, the three screw holes 19 provided in the outer periphery holding ring 18 and the screw holes 16 of the outer ends 11b of the three elastic base materials 11 are made to coincide with each other.
Further, the outer end 11b of the elastic base material 11 is sandwiched with the outer peripheral holding ring 18 by the outer male member 20 having a U-shaped cross section. At this time, the outer teeth 20 are held so that the screw holes 21 provided on the upper and lower sides of the outer member 20 are aligned with the screw holes 19 of the upper and lower outer retaining rings 18 aligned with the screw holes 16 of the elastic base material 11. deep. Then, the screw hole 21 of the outer member 20, the screw hole 19 of the outer periphery holding ring 18, the elastic base material 11
The screw 17 is inserted into the screw hole 16 of and fixed at three points.
As a result, the spring 10 as shown in the plan view of FIG. 2 and the sectional view of FIG. 7 is completed.

As shown in FIG. 6, a flat plate type mounting portion 22 is integrally formed on the back side of the outer member 20,
A screw hole 23 is provided substantially in the center of the mounting portion 22. Therefore, as shown in FIG. 7, the spring 10 can be attached to an object such as a Stirling engine by the screw 24 inserted into the screw hole 23. As shown in FIG. 8, the screw hole 16 of the inner end 11a or the outer end 11b of the elastic base material 11 is provided long along the spiral, and the spring constant is finely adjusted depending on the position where the screw 17 is inserted within the range. Is possible.

FIG. 1 shows a typical free piston type Stirling engine (hereinafter simply referred to as "Stirling engine").
Is a schematic cross-sectional view showing). First, the configuration and operation of the Stirling engine 186 will be described with reference to this figure.

The external portion of the Stirling engine 186 is composed of a pressure resistant container 174, a warm head 182 and a cold head 183, and a working medium such as helium is enclosed in a working space 178 therein.

Cylinder 17 forming a part of pressure vessel 174
A piston 171 and a displacer 172, which are slidable along the inner peripheral wall surface of the cylinder, are coaxially arranged in 4a. A rod 175, the inner end of which is fixed to the displacer 172, penetrates the center of the piston 171, and the outer end thereof is dismounted by the displacer spring 177.
It is elastically supported by 74. On the other hand, the piston 171 is elastically supported by the pressure resistant container 174 by a piston spring 176.

The working space 178 has a compression space 181a and an expansion space 181b, and the piston is a piston driving body 1 such as a linear motor housed in the back space 179.
80 reciprocates in the compression space 181a in the axial direction at a predetermined cycle. The piston spring 176 plays a role of stabilizing the cycle of the piston 171 that has started reciprocating substantially constant.

Reference numeral 173 is a regenerator, which is the expansion space 1
The cold heat is recovered from the working medium moving from 81b to the compression space 181a side and stored therein, and the stored cold heat is transferred to the working medium moving from the compression space 181a to the expansion space 181b side to cool it. According to this, the temperature change due to the contraction / expansion of the working medium that reciprocates between the compression space 181a and the expansion space 181b becomes large, and the cold heat can be efficiently extracted from the Stirling engine 186.

Upon being compressed in the compression space 181a, the working medium passes through the regenerator 173 and moves to the expansion space 181b side. Therefore, the displacer 172 is the piston 1
The piston 171 reciprocates in the axial direction at the same cycle as the piston 171 while maintaining a predetermined phase difference with the piston 71. As a result, the working medium is repeatedly compressed and expanded with sinusoidal pressure fluctuations in the expansion space 181b.

The displacer spring 177 is set with a spring constant and the like so as to stabilize the displacer 172 that has started reciprocating in the same cycle as the piston 171 and maintain a constant phase difference with the piston 171. The working medium expanded in the expansion space 181b is
Since the temperature is low, the cold head 183 is cooled and heat is taken from the outside. On the other hand, the working medium compressed in the compression space 181a becomes high temperature and the warm head 1
82 is heated to release heat to the outside.

Further, the piston 171 and the displacer 1
In order to reduce the vibration of the Stirling engine 186 mainly generated in the axial direction due to the reciprocating motion of the 72, the anti-vibration spring 184 and the metal having a predetermined weight are provided at the end of the Stirling engine 186 opposite to the cold head 183. An anti-vibration mechanism including a lid 185 is provided.

FIG. 9 shows a variable spring constant type spring 10 of the present invention.
FIG. 11 is a cross-sectional view for explaining the work of adjusting the spring constant after assembling to the Stirling engine 186. As shown in FIG. 9, the spring 10 is provided as a piston spring 176 and a displacer spring 177 in parallel with their centers aligned. First, as shown in FIG. 9A, the screw 190 on the outer periphery of the pressure resistant container 174 is removed to disassemble the pressure resistant container 174. Then, as shown in FIG. 9B, the spring constants of the displacer spring 177 and the piston spring 176 are adjusted. To adjust the displacer spring 177, loosen the screw 17 for holding the outer circumference with a screwdriver or a wrench, and
(See FIG. 8) Move it back and forth in the direction, and when the position is determined, tighten the screw again. Elastic base material 1 whose position you want to correct
Do for 1. Since the upper displacer spring 177 interferes with the piston spring 176, a hexagon wrench or the like is inserted from the side and the piston spring 176 is adjusted in the same manner as the displacer spring 177.

The spring 10 connected in this way is
Due to its structure, the spring 10 is provided in the vicinity of the joint portion between the elastic base material 11 and the target object, the inner teeth 14, the outer peripheral holding ring 18, and the like.
It is conceivable that cracks may occur when the edges touch each other due to the effects of long-term operation, such as the amount of displacement and the stress on the spring. Therefore, as shown in FIG.
A donut-shaped washer 25 having a rounded edge is sandwiched between the inner tooth 14 and the elastic base material 11, and the edge is rounded between the outer peripheral holding ring 18 and the elastic base material 11 inside the outer tooth 20. Insert the flat washer 26 with the. Thereby, the generation of cracks can be suppressed.

FIG. 11A is a plan view of the flat washer 26, and FIG. 11B is a side view thereof. A screw hole 27 through which the screw 17 is inserted is provided at the center. Instead of the flat washer 26, a spherical spacer 28 as shown in FIG. 12 may be used.

In addition to the above reasons, the spring 10 may be damaged due to aged deterioration. In that case, the function as a spring can be restored by replacing only the damaged parts, so that the labor and cost for repairing are greatly increased. To be omitted.

[0031]

As described above, since the variable spring constant type spring of the present invention is made of a combination of a plurality of spiral elastic base materials, the spring in the radial direction when the entire spring is seen in a plane is viewed. There is little variation in the spring constant, and its adjustment can be done easily. That is, the spring constant can be increased to a predetermined value by cutting the elastic base material from the outer end of the spiral by a predetermined length.

Further, by providing a screw hole at the outer end portion of the elastic base member in the spiral direction so as to be long, the spring constant is small even after the spring is assembled to the object according to the position of the screw inserted into the screw hole. It can be adjusted.

Further, even if a part of the spring is damaged due to aging, the function as the spring can be restored by replacing only the damaged part, so that the labor and cost for repair can be greatly saved.

In a Stirling engine incorporating such a spring as a displacer spring and a piston spring, the spring constant can be adjusted while performing an operation test after assembly, so that the performance as designed can be stably obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a hand money showing an example of a free piston type Stirling engine.

FIG. 2 is a plan view showing a spring constant type spring of the present invention.

FIG. 3 is a plan view of an elastic base material used for the spring constant variable spring.

FIG. 4 is an enlarged view of a main part for explaining that an outer end portion of the elastic base material is cut to increase a spring constant.

FIG. 5 is a plan view showing a state where the central portions of three elastic base materials are fixed.

FIG. 6 is a perspective view for explaining a method of fixing outer peripheral portions of three elastic base materials.

7 is a cross-sectional view of the spring constant variable spring of FIG.

FIG. 8 is a plan view (a) and a side view (b) showing an example in which a screw hole at an outer end portion of an elastic base material is formed as an elongated hole.

FIG. 9 is a cross-sectional view for explaining an example of a method of adjusting a spring constant after assembling in a Stirling engine equipped with a spring constant variable spring of the present invention.

10 is a cross-sectional view of the spring constant variable spring of FIG.

FIG. 11 is a plan view (a) and a side view (b) of the flat washer.

FIG. 12 is a plan view (a) and a side view (b) of the spherical spacer.

[Explanation of symbols]

10 Spring constant variable spring 11 Elastic base material 14 Inside 15,16,19,21,23 screw holes 17,24 screws 18 Peripheral retaining ring 20 Outside 22 Attachment 176 Piston spring 177 Displacer Spring 186 Stirling engine

Claims (7)

[Claims] 1. A plurality of elastic base materials formed with a predetermined width and thickness from an inner end having a minimum diameter to an outer end having a maximum diameter are combined in such a manner that their surfaces in the thickness direction face each other. A variable spring constant type spring characterized in that. 2. The spring constant variable spring according to claim 1, wherein the spring constant can be changed to an arbitrary spring constant by cutting the elastic base material from the outer end by a predetermined length. 3. The spring constant can be finely adjusted by providing a screw hole penetrating in the thickness direction at the inner end or the outer end, and adjusting the spring constant depending on the position where the screw is inserted within the range. 2. A variable spring constant spring according to item 2. 4. The variable spring constant spring according to claim 1, wherein the inner end portion is integrated with a disk. 5. The variable spring constant type spring according to claim 4, wherein the outer end portion is integrated with a ring-shaped holding member. 6. A doughnut-shaped washer with rounded edges is sandwiched between the disk and the elastic base material, and a flat washer with rounded edges is sandwiched between the ring-shaped holding member and the elastic base material. The spring constant variable spring according to claim 5, wherein 7. A Stirling engine having a piston and a displacer that reciprocate in the same direction with a predetermined phase difference in a cylinder, wherein the variable spring constant spring according to claim 1 is used as the piston spring and the displacer spring. A Stirling engine that is equipped with.