JPH07286763A - Compressor - Google Patents

Abstract

PURPOSE:To restrain the generation of contamination by a method wherein the usage of adhesive agent is reduced as much as possible while securing a necessary strength of connection. CONSTITUTION:The diameter of a shaft for a metallic piston 5 is made larger than the diameter of hole of a sliding member 57 made of synthetic resin. The piston 5 is fitted into the sliding member 57 through force fitting to fit it under the condition of close fit. An adhesive agent layer 59 is formed between both of the members 5, 5 7. A clamping force is generated between both of the members 5, 57 by the close fit whereby the strength of connection depending on the adhesive agent can be reduced by an amount corresponding to the clamping force. The engaging surface of the piston 5 is finished so as to have the surface roughness of 10S or more to 50S or less. According to this method, the securing of, a necessary strength of connection and the reduction of of the usage of adhesive agent can be contrived surely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor in which a piston fitted in a cylinder is reciprocally moved by a linear motor to generate a pressure wave in a working fluid in the cylinder.

[0002]

2. Description of the Related Art Conventionally, this type of compressor has been used, for example, in a free displacer type Stirling refrigerator, and the refrigerator can cool to an extremely low temperature level.
As shown in FIG. 7, in addition to the compressor (a), an expander (b) for expanding a refrigerant gas as a working fluid discharged from the compressor (a) is provided.

The compressor (a) is, for example, a hermetically-sealed casing (c), a cylinder (d) housed in the casing (c), and reciprocally fitted in the cylinder (d). And a linear motor (f) that drives the piston (e). The cylinder (d) is provided at the lower end of the cylinder (d) with the casing (c).
Is provided with a flange (g), an annular permanent magnet (h) is provided on the upper surface of the flange (g), and a magnetic field is applied to the gap between the permanent magnet (h) and the cylinder (d). Is forming. A substantially inverted cup-shaped bobbin (i) integrally provided with the piston (e) is arranged in the gap, and a coil (j) is provided in the bobbin (i). Further, the piston (e) is formed by the coil spring (k) into the casing (c).
It is elastically supported by. Then, due to the interaction between the coil (j) and the permanent magnet (h), the piston (e), the coil spring (k), and the refrigerant gas as the working fluid in the compression chamber (e) form one vibration system. Resonance causes the piston (e) to reciprocate to generate a pressure wave of a predetermined cycle in the refrigerant gas in the cylinder (d).

On the other hand, the expander (b) comprises a cylindrical cylinder (m) and a free displacer (n) fitted in the cylindrical cylinder (m) so as to be reciprocally movable. (N) divides the space in the cylindrical cylinder (m) into an expansion chamber (o) and a working chamber (p). In the working chamber (p), a displacer spring (q) formed of a coil spring that elastically supports the free displacer (n) on the cylindrical cylinder (m) is arranged. The free displacer (n) is filled with a regenerator material (r) made of metal, and the end portion on the expansion chamber (o) side allows the gas to flow between the expansion chamber (o) and the first communication. The holes (s) are respectively provided with second communication holes (t) at the end on the working chamber (p) side for allowing gas to flow between the holes and the working chamber (p). Further, the working chamber (p) communicates with the compression chamber (e) of the compressor (a) through the coupling pipe (u), and reciprocates the free displacer (n) by the pressure wave from the compressor (a). Move the refrigerant gas to the expansion chamber (o)
In this way, cold is generated in the cold head at the tip of the cylindrical cylinder (m).

[0005]

By the way, in the above compressor (a), an adhesive may be used for joining the constituent members, and this adhesive absorbs gas during manufacturing,
The absorbed gas (outgas) is gradually released into the compressor (outgassing). Because the gas release rate of the adhesive is higher than that of metal, the refrigerant gas, which requires extremely high purity, is contaminated (contamination) in a short time to a value lower than the predetermined allowable purity, and the compressor is compressed. There is a problem that the life of (a) is shortened.

When an adhesive is used to join the constituent members, for example, as shown in FIGS. 8 and 9, the piston (e) is slid on the piston (e) for smooth sliding. The moving member (v) may be joined. That is,
After applying the adhesive to the outer peripheral surface of the piston (e), the sliding member (v) is externally fitted to the piston (e), and the adhesive layer (w) is placed between the both members (e) and (v). Is formed. In order to obtain a predetermined bonding strength only with the adhesive, it is necessary to increase the thickness of the adhesive layer (w). For example, a creep test that measures the thickness of the adhesive layer (w) and the time to reach rupture usually requires a durability time of 200 hours or more. To achieve this durability time, the adhesive layer (w) is required.
Had to be as large as 50 to 100 μm, which was a cause of contamination.

Another case in which an adhesive is used is as follows. That is, both ends of the coil spring (k) are fixed to the piston and the casing, respectively, and an adhesive is usually used for this fixing. This is because the coil spring (k) when the joint part is loosened.
This is because the spring constant changes and an abnormal operating state occurs in which a pressure wave having a predetermined period cannot be generated. Therefore, conventionally, the coil spring has been molded with a relatively large amount of adhesive, which has been a cause of contamination.

The present invention has been made in view of the above points, and an object of the present invention is to generate a tightening force between two mating members in a compressor in which high purity of working fluid is required. By doing so, it is possible to reduce the amount of the adhesive used as much as possible while suppressing the occurrence of contamination while ensuring the required bonding strength.

[0009]

[Means for Solving the Problems] In order to achieve the above-mentioned object, a solution means of the invention according to claim 1 is a cylinder (3) provided in a casing (1) as a compressor.
And a linear motor (7) for reciprocatingly moving the piston (5) inserted into the cylinder (3) so that the piston (5) reciprocates. It is assumed that a pressure wave is generated in the working fluid in the cylinder (3). In such a compressor, when the piston (5) reciprocates on either the inner peripheral surface of the cylinder (3) or the outer peripheral surface of the piston (5), A tubular sliding member (57) that reduces frictional resistance with the cylinder (3) is fitted. Of the piston (21) or the cylinder (3) into which the sliding member (57) is fitted and the sliding member (57), the shaft side member which is the shaft side of the fitting is the shaft diameter ( E) is set to be larger than the hole diameter (F) of the perforated member on the side of the fitting hole, and is fitted into the perforated member by shrinkage fit or press fit.

Further, a solution means taken by the invention according to claim 2 is that in the compressor according to claim 1, one of the shaft side member and the perforated member is a metal member,
The other is made of a synthetic resin member, the metal member and the synthetic resin member are fitted by press fitting, and an adhesive agent is applied between both members to form an adhesive layer (59). The fitting surface (5a) of the manufacturing member is finished to have a surface roughness in the range of 10 S or more and less than 50 S.

Further, the means for solving the problems of the invention according to claim 3 is that, as a compressor, a cylinder (3) provided in a casing (1) and a reciprocatingly-movable insertion into the cylinder (3). And a coil spring (3) for elastically supporting the piston (5) on the casing (1).
9) and a linear motor (7) that reciprocates the piston (5), and it is premised that a pressure wave is generated in the working fluid in the cylinder (3) by the reciprocating movement of the piston (5). To do. And in such a compressor, the said casing (1) and the said piston (5).
At least one of them is formed with a convex spring fixing portion (31), (37) for fixing one end of the coil spring (39), and the spring fixing portion (31), (37) has The diameter is set to be larger than the coil inner diameter of the coil spring (39), and the coil spring (39) is fitted into the coil spring (39) by shrinkage fitting or press fitting.

Further, the solution means taken by the invention according to claim 4 is the compressor according to claim 3, wherein the coil spring (3) is provided on the outer peripheral surfaces of the spring fixing portions (31), (37).
9) is provided with a fitting groove (65) into which the fitting groove (6) is fitted.
The minimum outer diameter (M) of the spring fixing portions (31) and (37) in 5) is set to be larger than the coil inner diameter (N) of the coil spring (39).

[0013]

With the above construction, in the invention according to claim 1,
When the sliding member (57) is fitted on the outer peripheral surface of the piston (5), the piston (5) serves as the shaft side member and the sliding member (57) serves as the perforated member. Further, when the sliding member (57) is fitted to the inner peripheral surface of the cylinder (3), the sliding member (57) serves as an axial member and the piston (5) serves as a perforated member. Further, the shaft side member on the shaft side of the fit is set to have a shaft diameter (E) larger than the hole diameter (F) of the perforated member on the hole side of the fit, and the perforated member is contracted or press-fitted. Since the members (5) and (57) are fitted to each other, the fit between the members (5) and (57) is a tight fit, and a tightening force is applied to the members (5) and (57).

Particularly, in the invention according to claim 2, when the shaft side member is a metal member and the perforated member is a synthetic resin member, for example, the fitting surface (5a) of the metal member is exposed. An adhesive is applied to the metal member and the synthetic resin member is press-fitted.

The outer diameter of the metal member measured at the valleys of the irregularities of the fitting surface (5a) (see FIG. 3) and the outer diameter of the member whose surface of the fitting surface (5a) is not exposed (FIG. 9) When the adhesive layer (59) having the same thickness is formed on the fitting surface (5a) of each member, the adhesive is applied to the uneven ridges of the metal member. Therefore, the amount of adhesive adhered to the metal member is reduced as much as that of the metal member having a surface not exposed. Then, the fitting surface of the metal member (5
a) is finished to a surface roughness in the range of 10 S or more and less than 50 S, that is, the maximum depth of the valleys of the unevenness is 10 μm or more and 5
It is less than 0 μm. If it is less than 10S, the mating surface (5
The joint strength is insufficient because the valleys of the irregularities of a) are shallow and the adhesion amount of the adhesive is insufficient, and at 50S or more, the valleys of the irregularities are too deep and the adhesion amount becomes too large. Contamination due to outgassing becomes a problem. On the other hand, within the above range, it is possible to ensure the required bonding strength and reduce the amount of adhesive used.

In the invention according to claim 3, the spring fixing portions (31) and (37) have coil springs (3) whose outer diameters are equal to each other.
Since it is set to be larger than the coil inner diameter of 9) and is fitted into the coil spring (39) by shrinkage fitting or press fitting, the spring fixing portions (31) and (37) and the coil spring (3).
9) A tightening force is generated between and.

Moreover, in the invention according to claim 4, since the coil spring (39) is fitted in the fitting groove (65) of the spring fixing portions (31) and (37), the spring fixing portions (31) and (). Three
7) and the coil spring (39) are in surface contact with each other, and the wall of the fitting groove (65) prevents the coil spring (39) from moving in the axial direction, so that a large joint strength is obtained.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a compressor (A) for a Stirling refrigerator according to an embodiment of the present invention. The compressor (A) is a piston-opposed vibration type compressor, and is combined with a free displacer type expander (not shown) to form the Stirling refrigerator. The compressor (A) includes a casing (1), a cylinder (3) provided in the casing (1), and a pair of left and right pistons fitted in the cylinder (3) so as to be reciprocally movable. (5), (5) and a pair of linear motors (7), (7) for reciprocating the pistons (5), (5), respectively, the pair of linear motors (7), (7) Thus, the pistons (5) and (5) are synchronously reciprocated in opposite directions to generate a pressure wave in the refrigerant gas as a working fluid.

The casing (1) comprises a pair of left and right casing assemblies (9), (9) made of pure iron, and an annular center base (11) into which the casing assemblies (9), (9) are fitted. ) And.

Inside the casing (1), the cylindrical cylinder (3) whose both ends are open is installed in the casing (1).
Are arranged concentrically with the axis line (not shown). The cylinder (3) is composed of a pair of left and right cylinder members (15), (15) made of stainless steel, and a center side end portion of the pair of cylinder members (15), (15) is radially outward. Overhanging flange portions (17) and (17) are provided, respectively. Both flange parts (17), (17)
Are fitted and fixed to the center base (11) in an airtight manner, and are in close contact with the regulation plate (19) fitted to the inner peripheral surface of the center base (11).

Inside the cylinder (3), the pair of pistons (5), which are concentric with the axis of the casing (1),
(5) is provided, and a predetermined minute gap is formed between the cylinder (3) and both pistons (5) and (5). The space between the pair of pistons (5) and (5) in the cylinder (3) is a compression chamber (21). The flange portions (17), (17) have concave grooves (23) extending from the inner peripheral surface toward the outer peripheral surface,
(23) are provided respectively, and the flange portions (1
7), the first gas passage (2) for communicating the space formed by the concave grooves (23), (23) of (17) with the compression chamber (21)
5). In addition, the center base (11) has a second gas passage (2) communicating with the first gas passage (25).
7) is provided, and the second gas passage (27) is connected to the expander by a coupling pipe (not shown).

The casing assembly (9),
Spring assemblies (29), (29) for closing the openings are provided at the left and right opening ends of (9), and an assembly side holder (31) as a spring fixing portion is provided at the center of the inner surface of each spring assembly (29). ) Is attached. Further, each piston (5) has a central hole (33).
And a piston side holder (37) as a spring fixing portion is attached to the bottom surface of the center hole (33) by a screw member (35). A piston spring (39) as a coil spring is arranged between the holders (31) and (37). Both ends of each piston spring (39) are fixed to the holders (31) and (37), respectively, and the piston (5) is elastically supported by the spring assembly (29) by the piston spring (39).

Each of the linear motors (7) has a cylindrical member (41) made of pure iron fitted and fixed around the cylinder (3), and the outer peripheral surface of the cylindrical member (41) and the casing assembly. (9) A gap is formed between the inner peripheral surface and the inner peripheral surface. An annular permanent magnet (43) is fixed to the outer peripheral surface of the cylindrical member (41) with a predetermined gap from the inner peripheral surface of the casing assembly (9). Cylindrical member (41)
Also, the casing assembly (9) is used as a yoke to generate a magnetic field of a predetermined intensity in the gap (magnetic gap) between the permanent magnet (43) and the inner peripheral surface of the casing assembly (9) by the permanent magnet (43). There is.

At the end of the central hole (33) of each piston (5) on the opening side, a brim (45) is projected outward in the radial direction.
Is provided, and a cylindrical bobbin (49) having a bottom is connected to the flange portion (45) by a screw member (47). The bobbin (49) is made of thin stainless steel, which is a non-magnetic material, and its tip is arranged concentrically with the piston (5) so that it is located between the permanent magnet (43) and the inner peripheral surface of the casing assembly (9). It is located in the gap. A concave coil arrangement portion (51) having a predetermined width is provided on the outer peripheral surface of the tip end portion of the bobbin (49).
By winding a wire around 1), the bobbin (4
9) the coils (5) of the linear motors (7), (7)
3) is provided. The bobbin (49) and the coil (53) are capable of reciprocating in the axial direction (left and right direction in the drawing) in the gap between the permanent magnet (43) and the inner peripheral surface of the casing assembly (9). . Then, the coils (5) of both the linear motors (7) and (7) are
By supplying an alternating current of a predetermined frequency to 3), both pistons (5) and (5) reciprocate in the same phase in opposite directions.

Further, the piston (5) and the bobbin (4
9), the coil (53), the piston spring (39) and the refrigerant gas in the compression chamber (21) acting as a spring constitute a single vibration system. In the linear motors (7) and (7), the mass of the movable part including the piston (5), the bobbin (49) and the coil (53), the spring constant of the piston spring (39) and the compression chamber (21). Is set to a predetermined frequency (for example, 50 Hz) that is determined by the gas spring constant of the refrigerant gas, and is set to cause resonance in the vibration system.

In the casing (1), a restricting mechanism (55) for restricting the vibrations of the two pistons (5), (5) in the same direction in the cylinder (3) in the opposite phase mode. Is provided. The restriction mechanism (55) has the restriction plate (19) sandwiched between the cylinder members (15) and (15), and the restriction plate (19) has the first gas passage (25) on the left side. It is divided into a diversion passage (25L) and a right diversion passage (25R). And the compression chamber (21)
The flow path resistance of the flow path that returns from the left side diversion passageway (25L), the second gas passageway (27), and the right side diversion passageway (25R) to the compression chamber (21) becomes Flow passage resistance (left side diversion passage (25L)-
It is set to be larger than the flow path resistance between the second gas passage (27) and the connecting pipe, the right side flow passage (25L) -the flow path resistance between the second gas passage (27) and the connecting pipe). The large flow path resistance restricts the pistons (5) and (5) from vibrating in the antiphase mode.

Next, the operation of the Stirling refrigerator will be described. By alternating current to the coils (53) of both linear motors (7) and (7) in the compressor (A), alternating current is applied to the coils (53). A magnetic field is generated and the pair of pistons (5) and (5) are reciprocated by the interaction between the alternating magnetic field and the magnetic field of the permanent magnet (43). The pistons (5) and (5) reciprocally move in opposite directions to each other in the same phase to increase or decrease the volume of the compression chamber (21) and generate a pressure wave of a predetermined cycle in the refrigerant gas in the compression chamber (21). Let
The pressure wave in the compression chamber (21) is generated by the two gas passages (25),
Propagate to the working chamber of the expander via (27) and the connecting pipe. Due to the pressure wave, the displacer of the expander reciprocates in the same cycle as the pressure wave to expand and cool the refrigerant gas in the expansion chamber.

The pistons (5) are made of metal, and the outer peripheral surface of the pistons (5) is made of synthetic resin and has a cylindrical sliding member (5) as a perforated member, as shown in FIGS.
7) is externally fitted via an adhesive layer (59), the piston (5) constitutes a metal member, and the sliding member (57) constitutes a synthetic resin member. The piston (5) is a shaft side member which is the shaft side of the fit, and the sliding member (57) is a perforated member which is the hole side of the fit. The sliding member (57) has a predetermined small coefficient of friction to reduce frictional resistance between the piston (5) and the cylinder (3) when the piston (5) reciprocates. There is.
As the above-mentioned sliding member (57), for example, one obtained by adding various fillers to a base material of PTFE (polytetrafluoroethylene) is used. Below, to improve the sliding characteristics 4
Examples of seed fillers are given. Any one of these four types of fillers is used.

1. Glass fiber and pigment 2. Polyimide 3. Graphite 4. Carbon fiber The shaft diameter (E) of the piston (5) is set to be larger than the hole diameter (F) of the sliding member (57), and both members (5), (5)
The fitting of 7) is in a tight fit state, and the tightening force acts between both members (5) and (57).

Fitting surface (5a) on the outer circumference of the piston (5)
Is represented by turning. Both members (5),
The joint strength of (57) is set to a predetermined value (for example, 200 kgf or more) at which both the members (5) and (57) are in a retaining state. The fitting surface (5a) is roughened by turning and finished to have a surface roughness in the range of 10 S or more and less than 50 S. Therefore, the maximum depth of the concave and convex valleys (61) of the fitting surface (5a) is 10 μm or more and less than 50 μm, and the conventional depth is 50S to 100S (the maximum depth of the concave and convex valleys is 5 μm).
0 μm to 100 μm). The range is set to be less than 10S because the concaves and convexes (61) of the fitting surface (5a) are shallow and the amount of adhesive is insufficient, resulting in insufficient bonding strength. This is because the adhesion amount becomes too large due to the excessive depth, and contamination due to gas (outgas) generated from the adhesive becomes a problem. Desirably, the range of the surface roughness is 10S to 15S. This is because it is possible to reduce the adhesion amount of the adhesive while ensuring the required bonding strength.

To provide the sliding member (57) on the piston (5), as shown in FIG. 3, first, an adhesive is applied to the fitting surface (5a) of the piston (5), and the fitting surface (5a) is applied. Fill the valleys (61) of the unevenness generated in 5a). After that, a thick sliding member material (B) having a hole diameter (F) smaller than the shaft diameter (E) of the piston (5) is press-fitted into the pistons (5) and (5). As a result, the adhesive layer (59) is formed in the concave and convex valleys (61). The sliding member (57) made of a synthetic resin having a low hardness comes into close contact with the outer peripheral surface of the piston (5) with a predetermined tightening force while slightly expanding. After drying the adhesive,
The sliding member material (B) is cut to form a sliding member (57) having a predetermined thickness.

Then, the outer diameter (G) (see FIG. 3) measured at the valleys (63) of the irregularities of the member (processing member) having the fitting surface (5a) and the fitting surface are exposed. When the outer diameter (H) (see FIG. 9) of a non-treated member (untreated member) is made the same, an adhesive layer (59) having the same height as the unevenness of 10 S or more and less than 50 S is formed on the untreated member. Once formed, no adhesive is applied to the uneven ridges (63) of the treated member, so the amount of adhesive adhered to the treated member is reduced by that amount as compared to that of the untreated member.

The joint structure between the piston spring (39) and the holders (31) and (37) will be described with reference to FIGS. 4 and 5.
1) and (37) are provided with a fitting groove (65) on the outer peripheral surface thereof, and the holders (31) in the fitting groove (65),
The minimum outer diameter (M) of (37) is the piston spring (3
It is set to be larger than the coil inner diameter (N) in 9). Then, the both ends of the piston spring (39) are fitted into the fitting groove (65) by press-fitting into the fitting groove (65) of the holders (31) and (37) while rotating the piston spring (39). Fit and fix to. Mating groove (65)
One to two turns of the piston spring (39) are fitted and fixed to the.

As described above, according to the above embodiment, the shaft diameter (E) of the pistons (5), (5) is set larger than the hole diameter (F) of the sliding member (57). A tightening force is generated between the two members (5) and (57), the bonding strength of the adhesive can be reduced accordingly, the amount used can be reduced, and the occurrence of contamination can be suppressed.

Further, the mating surface (5a) is 10S or more 50
Since the surface roughness is finished within the range of less than S, it is possible to ensure the required bonding strength and reduce the amount of adhesive used, and to achieve effective bonding.

The outer diameters of the holders (31) and (37) are the inner diameter (N) of the coil of the piston spring (39).
Since it is set larger than the above, a large tightening force acts between the piston spring (39) and the holders (31) and (37). Moreover, both holders (3
Since the piston spring (39) is fitted in the fitting groove (65) of 1) and (37), both holders (31),
(37) is in surface contact with the piston spring (39), and the wall of the fitting groove (65) is in contact with the piston spring (3).
The movement in the coil axial direction of 9) (the same direction as the axial direction of the casing (1)) is prevented, and a large joint strength is obtained. As a result, the piston spring (39) can be prevented from coming off without using an adhesive, and contamination can be eliminated. Furthermore, it prevents the looseness of the joined state,
It is also possible to eliminate the occurrence of contamination while always maintaining the vibration system in a predetermined resonance state.

The present invention is not limited to the above embodiment, but includes various modifications. For example, although the piston (5) is fitted to the sliding member (57) in the above embodiment, the sliding member (57) may be fitted to the cylinder member (15). In this case, the sliding member (5
7) becomes the shaft side member, and the cylinder member (15) becomes the perforated member.

Further, in the above embodiment, the case where the metal piston (5) and the sliding member (57) made of synthetic resin are press-fitted has been described. However, metal is put in both the members (5) and (57). By using a shrink fit, both members (5), (5
7) may be joined. In this case, since a large tightening force is generated, it is possible to use no adhesive at all.

Further, in the above embodiment, the fitting surface (5a) of the piston (5) which is the shaft side member is shown, but the fitting surface of the sliding member (57) which is the perforated member is shown. You can do it.

In the above embodiment, the piston spring (39) is fitted in the fitting groove (65) of the holders (31) and (37), but the holders (3) are not always required.
It is not necessary to provide the fitting groove (65) in 1) and (37),
Attach the piston spring (39) to both holders (31),
You may fit on the outer peripheral surface of (37).

The minimum outer diameter (M) is the coil inner diameter (N)
More than that, both holders (31), (37)
Either of them may be used.

Next, a test for confirming the joint strength between the piston and the sliding member was conducted. This will be described below. (Sample) Piston: Brass shaft Sliding member: BEAREE FL3030 (LURON J) bush The inner surface of the bush has been TOS treated. Adhesive: Sumitomo 3M epoxy resin adhesive DP-190
(Gray) Shaft fitting and surface roughness: See Table 1 (Sample preparation and test method) Shaft surface is roughened. For all the shafts, the number of troughs of unevenness per unit area was kept constant, and only the surface roughness was changed for each shaft. After applying the adhesive to the shaft, the bush was press-fitted to produce a sample. 24 of the sample
After allowing to stand naturally for a time, the bonding strength was measured by a tensile compression tester manufactured by Shimadzu Corporation. For the measurement, as shown in FIG. 6, the sample was set below the pressing jig (67) of the tester, and then the pressing portion (67a) of the pressing jig (67) was brought into contact with the bush (69). . The pushing jig (67) was lowered to apply a downward force to the sample bush (69), and the bush (69) was peeled off from the shaft (71). As a comparative example, the shaft (7
The one in which 1) and the bush (69) were fitted was manufactured, and the same test was conducted.

(Measurement conditions) Test speed: 50 mm / min Stroke (S in FIG. 6): 10 mm Chart full scale: 500 kgf Chart ratio: 10 times (measurement items and measuring equipment used) Bonding strength: Tensile compression testing machine Appearance Situation (inner peripheral surface and outer peripheral surface of bush): Microscope Shaft surface roughness: Surface roughness measuring instrument The measurement results were as shown in Table 1. Although not shown in Table 1, the bonding strength of the sample having a surface roughness of less than 10 S was smaller than 200 kgf. Further, in the conventional case in which the adhesive layer having a thickness of 50 μm or more was formed without roughening the surface of the shaft, the adhesive adhesion amount was obviously larger than in Samples A to C, and therefore the measurement was not performed.

[0044]

[Table 1]

(Conclusion) From Table 1, the bonding strengths of Sample B, Sample C, Sample A (A-1, A-2, A-3) and Comparative Example (A
-4, A-5) in that order. It is considered that the strength of Sample B is the largest because the surface roughness of the shaft is large. Among the samples A and C having the same surface roughness, the sample C has a higher strength because the interference is smaller than that of the sample A and the amount of the adhesive extruded is small. Although the sample C has a higher bonding strength than the sample A, the amount of adhesive adhered on the shaft side is small and the sample is broken at the adhesive layer. On the other hand, sample A has a larger amount of adhesive adhered than sample C and ruptured at the bush member portion, so sample A is superior to sample C in the bonding state. From the comparative example in which no adhesive is used, it can be seen that the tightening force acts between both members due to the interference fit. In each of Samples A to C, since the adhesive is attached to the surface of the shaft that is exposed, the amount of the adhesive is smaller than that of the shaft where the surface is not exposed. Between each sample, the adhesive adhesion amount was larger in the order of sample B, sample C, and sample A.

From the above, since the samples A to C have the necessary bonding strength (200 kgf), the sample A having a small amount of adhesive adhered is the most dominant. Among the samples B and C, the sample B having an excellent joined state is dominant. As a result, Sample A, Sample B, and Sample C are superior in this order.

Next, a tensile test was conducted on the piston spring and the holder. First, a piston spring was pressed into the fitting groove of the holder without applying an adhesive, and a sample was manufactured. A tensile force was applied to the sample in the direction of separating the two members. With the degree of the force acting on the joint between the two members when the compressor was operating, the joint did not loosen, and when a tensile force was applied, the holder broke and the two members separated.
From this, it was confirmed that the two members were not separated and the joint was not loosened during the operation of the compressor even without the adhesive.

[0048]

As described above, according to the compressor of the first aspect of the present invention, since the shaft side member and the perforated member are fitted by shrinkage fitting or press fitting, there is no space between both members. The tightening force is generated, the amount of the adhesive used is reduced accordingly, and the generation of outgas can be reduced. It is possible to suppress the generation of contamination that contaminates the working fluid while ensuring the required bonding strength. In particular, when a metal is used for both the members and the two members are joined by shrinkage fitting, a large tightening force is generated, so that it is possible to use no adhesive at all.

Further, according to the invention of claim 2, when a metal member is used for one of the shaft side member and the hole member and a synthetic resin member is used for the other member, the fitting surface (5a) of the metal member is used. ) Is finished to have a surface roughness in the range of 10 S or more and less than 50 S, the maximum depth of the valleys of the irregularities on the mating surface (5a) is 10 μm or more and less than 50 μm, which ensures the necessary bonding strength and the amount of adhesive used. The reduction can be surely achieved, and the effective joining becomes possible.

According to the third aspect of the invention, the spring fixing portions (31) and (37) and the coil spring (39) are fitted by shrinkage fitting or press fitting, so that the spring fixing portion ( A tightening force is generated between the coil springs (39) and (37) and the coil spring (39), and the amount of adhesive used can be reduced by that amount, and the occurrence of contamination can be suppressed while ensuring the necessary bonding strength. .

Further, according to the invention of claim 4, since the coil spring (39) is fitted in the fitting groove (65) of the spring fixing portions (31) and (37), the spring fixing portion ( Three
1), (37) and the coil spring (39) are in surface contact with each other, and the wall of the fitting groove (65) blocks the movement of the coil spring (39) in the coil axial direction, and the adhesive is used at all. Not only can the coil spring (39) be prevented from coming off, contamination can be eliminated, and further, it becomes possible to prevent loosening of the joining state that causes abnormal operation of the compressor.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a compressor according to an embodiment of the present invention.

FIG. 2 is an assembly diagram of a piston and a sliding member.

FIG. 3 is a view showing a state before assembling a piston and a sliding member.

FIG. 4 is an assembly diagram of a piston spring and a holder.

FIG. 5 is a view showing a state before the piston spring and the holder are assembled.

FIG. 6 is an explanatory diagram of a test method.

FIG. 7 is a sectional view of a conventional Stirling refrigerator.

FIG. 8 is a conventional assembly diagram of a piston and a sliding member.

FIG. 9 is a view showing a conventional state before assembling a piston and a sliding member.

[Explanation of symbols]

1 Casing 3 Cylinder 5 Piston 5a Fitting Surface 7 Linear Motor 31 Assembly Side Holder (Spring Fixing Part) 37 Piston Side Holder (Spring Fixing Part) 39 Piston Spring (Coil Spring) 57 Sliding Member 65 Fitting Groove E Piston Shaft Diameter (shaft diameter of shaft-side member) F Hole diameter of sliding member (hole diameter of perforated member) M Minimum outer diameter of assembly side holder and piston side holder N Coil inner diameter of piston spring

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masao Ohno 1304 Kanaoka-machi, Sakai-shi, Osaka Daikin Industry Co., Ltd.Kanaoka factory (72) Inventor Ryuzo Tonoshima 1304, Kanaoka-machi, Sakai-shi, Osaka Daikin Industry Co., Ltd. Sakai Plant Kanaoka Factory

Claims (4)

[Claims] 1. A cylinder (3) provided in a casing (1), a piston (5) inserted in the cylinder (3) so as to be reciprocally movable, and the piston (5) is reciprocally moved. A compressor provided with a linear motor (7) for generating a pressure wave in a working fluid in the cylinder (3) by reciprocating movement of the piston (5), the inner peripheral surface of the cylinder (3) and the piston (3). 5)
The piston (5) and the cylinder (3) when the piston (5) reciprocates on either one of the outer peripheral surfaces of the cylinder (3).
The piston (21) is fitted with a tubular sliding member (57) for reducing frictional resistance between the piston and the sliding member (57).
Or, of the cylinder (3) and the sliding member (57), the shaft side member on the shaft side of the fit is the hole diameter (F) of the perforated member whose shaft diameter (E) is the hole side of the fit. A compressor that is set larger than the above and is fitted into the perforated member by shrinkage fitting or press fitting. 2. One of the shaft side member and the perforated member is made of a metal member and the other is made of a synthetic resin member, and the metal member and the synthetic resin member are fitted by press fitting. And an adhesive layer (59) is formed between both members to form an adhesive layer (59), and the fitting surface (5a) of the metal member is finished to have a surface roughness in the range of 10S or more and less than 50S. The compressor according to claim 1, wherein: 3. A cylinder (3) provided in a casing (1), a piston (5) fitted in the cylinder (3) so as to be capable of reciprocating movement, and the piston (5) provided in the casing (3). A coil spring (39) elastically supported by 1),
A compressor that includes a linear motor (7) that reciprocates the piston (5), and that generates a pressure wave in the working fluid in the cylinder (3) by the reciprocating movement of the piston (5), wherein the casing (1 ) And at least one of the piston (5) is provided with convex spring fixing portions (31) and (37) for fixing one end of the coil spring (39), and the spring fixing portion (31). , (37) has an outer diameter larger than the inner diameter of the coil spring (39) and is fitted into the coil spring (39) by shrinkage fit or press fit. Machine. 4. A fitting groove (6) into which the coil spring (39) is fitted, on the outer peripheral surface of the spring fixing portions (31), (37).
5) is provided, and the minimum outer diameter (M) of the spring fixing portions (31) and (37) in the fitting groove (65) is set to be larger than the coil inner diameter (N) of the coil spring (39). The compressor according to claim 3, wherein