WO2003042537A1

WO2003042537A1 - Linear compressor

Info

Publication number: WO2003042537A1
Application number: PCT/JP2002/011927
Authority: WO
Inventors: Teruyuki Akazawa; Sadao Kawahara; Nobuaki Ogawa; Hiroshi Hasegawa
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2001-11-15
Filing date: 2002-11-15
Publication date: 2003-05-22
Also published as: JP2003148339A; CN1585857A; KR20040066120A

Abstract

A linear compressor comprises a cylinder (10), a piston (20), a cylinder end surface (11), a movable section (40) and a stationary section (50) that constitute a linear motor, coil springs (15, 30), a head cover (80), a support mechanism (90), a sealed container (100), etc. Defined in the cylinder (10) is a compression chamber (13) for gas compression. The spring member (61) of a spring mechanism member (60) is composed of coil springs (15, 30) having predetermined spring rigidity. When the coil spring (15) is compressed to the fullest extent, a clearance is secured between the end surface of the piston (20) and the cylinder end surface (11), whereby the amplitude of the piston (20) of the linear compressor can be controlled.

Description

Specification

Linear compressor technical field

The present invention relates to a linear compressor for compressing gas by reciprocating a piston fitted in a cylinder by a linear motor. Background art

In the refrigeration cycle, 1 "] 〇 (typically 1 =! 22) is said to destroy the ozone layer due to the stability of its physical properties. In recent years, it has been used as an alternative refrigerant to HCFC-based refrigerants. Although HFC-based refrigerants are used, these HFC-based refrigerants have the property of promoting warming phenomena, so recently, HC-based refrigerants that do not significantly affect the ozone layer destruction and warming phenomena However, HC-based refrigerants have begun to be adopted, however, since HC-based refrigerants are flammable, it is necessary to prevent explosion and ignition from the viewpoint of ensuring safety, and as a result, the amount of refrigerant used is reduced as much as possible. On the other hand, the HC-based refrigerant has no lubricity as a refrigerant itself and has a property of easily dissolving in a lubricant. Or oil-poor compressor Linear compressors that have a small load in the direction perpendicular to the axis of the piston and low sliding surface pressure are reciprocating compressors, rotary compressors, and scroll compressors that have been widely used in the past. Compared to the machine, the oil-less type is easier to use, and the piston movable part is a free piston stroke where the piston position is freely determined by the motor thrust applied to the motor and the operating pressure conditions Also known as a compressor.

However, since this linear compressor is a free piston stroke, it is not mechanically picked up by other members. When the end face collides with the cylinder end face, a collision sound is generated, which may damage the piston and the like.

■ In addition, the linear compressor has a sliding surface between the cylinder and the piston, and the sliding performance of this sliding surface affects the efficiency and durability of the linear compressor. Further linear pressure In order to make a compressor compact without oil, only a simple one-way axial force acts between the cylinder and the piston.For example, it is important to minimize the generation of twisting force due to the coil spring supporting the piston. is there.

Accordingly, an object of the present invention is to provide a highly reliable compressor that prevents collision between a piston and a cylinder end face even during operation and transportation.

Another object of the present invention is to provide a linear compressor suitable for downsizing by reducing the size of the coil spring. Disclosure of the invention

According to a first embodiment of the present invention, a compression mechanism for compressing a gas and a linear motor for operating the compression mechanism are provided in a closed container, the compression mechanism includes a cylinder and a piston, and the cylinder The linear motor has a fixed part connected to the cylinder and a movable part connected to the piston, and one end of the linear motor is connected to the piston or the movable part. And the other end is pressed against the cylinder or the fixed part, and the other end is pressed against the piston or the movable part and the other end is connected to the cylinder or the opposite side of the compression chamber. In the linear compressor, wherein the piston is movably supported in the axial direction by an anti-compression chamber-side coil spring pressed against the fixed portion, the biston end face and the piston when the compression chamber-side coil spring is most compressed. It is obtained by securing a gap between the cylinder end face. According to the present embodiment, the piston behavior is suddenly changed due to a pressure change during operation and a disturbance force at the time of transportation, and the amplitude of the piston is regulated by the compression chamber side coil spring when the amplitude of the piston is increased. Therefore, collision between the piston tip and the cylinder end face can be avoided.

The second embodiment according to the present invention is a linear compressor according to the first embodiment, wherein the compression chamber side coil spring is a non-linear coil spring. According to the present embodiment, the non-linear coil spring increases the spring load as the spring deflection increases. Therefore, it absorbs the velocity near the top dead center, which can be expected to reduce the impact force.

A third embodiment according to the present invention is the linear compressor in the second embodiment, wherein the non-linear coil spring is an unequal pitch coil spring. Form of this implementation According to the state, as the deflection of the unequal-pitch coil spring increases, the wire-to-wire adhesion increases, the effective number of turns decreases, and the spring load increases. Absorbs the approaching piston speed, reduces the impact force, and provides good durability.

A fourth embodiment according to the present invention is the linear compressor according to the second embodiment, wherein the nonlinear coil spring is a conical coil spring. According to the present embodiment, when the spring deflection increases, the same effect of the unequal-pitch coil spring becomes more pronounced, and the spring load increases greatly, so that the brake absorbs the piston speed approaching top dead center. It can work effectively, reduce the impact force of the piston, reduce the impact sound, and increase the reliability.

According to a fifth embodiment of the present invention, a compression mechanism for compressing a gas and a linear motor for operating the compression mechanism are provided in a closed container, wherein the compression mechanism has a cylinder and a biston, The linear motor has a fixed part connected to the cylinder and a movable part connected to the piston, and has one end pressed against the biston or the movable part and the other end. And one end of the coil spring that presses against the cylinder or the fixed portion on the compression chamber side and one end that presses against the piston or the movable portion and the other end presses against the cylinder or the fixed portion on the compression chamber side. In a linear compressor in which the piston is movably supported in the axial direction by a compression chamber-side coil spring, the compression chamber-side coil spring constant is smaller than the anti-compression chamber-side coil spring constant. That's bad. During operation, the piston is reset to the opposite side of the compression chamber by the gas force of the compression chamber. It is necessary to increase the amount of deflection on the anti-compression side by this offset amount. Therefore, if the coil spring constants on the compression chamber side and the non-compression side are the same, it is necessary to increase the maximum deflection from the free length of the spring to the close contact height. In the present embodiment, the coil spring constant on the compression chamber side and the coil spring constant on the anti-compression chamber side are increased, so that the coil constants on the compression chamber side and the counter compression side are determined by design rather than the same coupling. The maximum deflection of the spring can be reduced relative to the maximum stroke of the piston; Therefore, the coil spring can be made compact, and the size of the linear compressor can be reduced.

The sixth embodiment according to the present invention relates to a linear compressor in the fifth embodiment. The amplitude of the piston is a, the offset amount that is pushed toward the anti-compression chamber side by the gas force applied from the compression chamber during operation, the coil spring constant of the compression chamber side is k1, and the coil spring of the anti-compression chamber side is Assuming that the constant is k2, the coil spring constant is determined so that the relational expression of k1X2k2X (a-) holds. According to the present embodiment, since the piston amplitude center position offset during operation is approximately halfway between the maximum deflections of the compression chamber side coil spring and the non-compression chamber side coil spring, the maximum deflection of the spring is reduced. Can be suppressed. Therefore, the coil spring can be made compact, and the linear compressor can be downsized.

According to a fourth embodiment of the present invention, in the linear compressor according to the first to sixth embodiments, the sectional shape of the coil spring is an oval or elliptical shape. In the present embodiment, by making the spring wire into an oval or elliptical cross-sectional shape, it is possible to reduce the maximum narcotic force generated in the wire at the time of spring deflection as compared with a round wire cross section. it can. Therefore, the height of the coil spring can be reduced, so that the coil spring can be made compact and the linear compressor can be downsized. '

An eighth embodiment according to the present invention is the linear compressor according to the first to seventh embodiments, wherein a refrigerant mainly containing carbon dioxide is used. Lubrication becomes severe with a high differential pressure refrigerant. Under CO 2 refrigerant, it is much more efficient and more reliable than other types of compressors.

FIG. 1 is a cross-sectional view showing the overall configuration of a linear compressor according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part showing a coil spring means of the present invention.

Figure 3 shows the load characteristics of the unequal pitch spring of the present invention.

FIG. 4 is an enlarged sectional view of a main part showing another coil spring means of the present invention.

Fig. 5 shows the load characteristics of the conical coil spring of the present invention.

FIG. 6 is a schematic view of the amount of deflection of a coil spring during operation according to an embodiment of the present invention.

Hereinafter, an embodiment of the linear compressor of the present invention will be described with reference to the drawings. First, figure 1, the overall structure of the linear compressor of the present invention will be described.

This linear compressor is roughly divided into a cylinder Ί〇, a piston 20, a movable part 4〇 and a fixed part 50 constituting a linear motor part, a spring mechanism part composed of a coil spring, and a head cover part 80. , A support mechanism 90, and a sealed container 100.

The cylinder 10 includes a cylinder end face 11 to which a valve element (not shown) is assembled, a flange 14, and a boss 12 protruding from the flange 14 toward one side (leftward in the figure). Become. The piston 2〇 includes a frame 22 that forms a recess for accommodating the support portion 21 and the coil spring 30. The piston 20 has a projection 23 provided on the inner bottom surface of the recess of the frame 22. A compression chamber 13 is formed between one end of the piston 20 and the cylinder end face 11.

The linear motor section includes a movable section 40 and a fixed section 5 mm. The movable section 40 includes a permanent magnet 41, a cylindrical holding member 42, and the like. The fixed portion 50 includes an inner yoke 51, an outer yoke 52, a coil 53, and the like. The permanent magnet 41 is held by the cylindrical holding member 42. The cylindrical holding member 42 is disposed concentrically with the piston 20 and held by the frame 22. The inner yoke 51 is formed of a cylindrical body, and is circumscribed and fixed to the pos portion 12 of the cylinder 10. A minute gap is formed between the outer periphery of the inner yoke 51 and the cylindrical holding member 42. The coil 53 is provided on the outer yoke 52. On the other hand, the outer yoke 52 is similarly formed of a cylindrical body, is arranged concentrically so as to form a minute gap on the outer periphery of the cylindrical holding member 42, and is fixed to the flange 14 of the cylinder 10.

As described above, the movable portion 40 and the fixed portion 50 are concentrically held with high precision, and the reciprocating motion can be smoothly performed.

The spring mechanism comprises a compression-chamber-side coil spring 15 and a counter-compression-chamber-side coil spring 30 having predetermined spring rigidity. These coil springs 15 and 3〇 are always used as compression springs that are used in a state of being compressed more than the natural length. One end 16 of the compression chamber side coil spring 15 is coupled to a step 19 formed on the other end surface of the piston 20. The other end 17 of the compression chamber-side coil spring 15 is connected to the outer peripheral end surface 18 of the boss 12 of the cylinder 1〇. One end 3 1 of the anti-compression chamber side coil spring 30 is It is joined to the projection 23 formed on the end face. The other end 32 of the anti-compression-chamber side coil spring 3 される is connected to the projection 63. The anti-compression chamber side coil spring 3〇 presses the coil springs 15 and 30 against the screw 20 with the spring fixing member 62 in order to generate a preload due to compression bending. The spring fixing member 62 is provided in a state of being bridged over an outer yoke 52 that becomes the fixing portion 50 of the linear motor portion, and is fixedly connected to an end of the outer yoke 52.

The closed container 100 is formed of a cylindrical container, and forms a space 101 inside. The components of the linear compressor are housed in this space 1-1. In addition, the sealed container 100 is provided with a suction pipe (not shown) and a discharge pipe (not shown). The support mechanism 9 、 has a plurality of coil springs 9 1, 92 disposed between the components of the linear compressor and the closed casing 1 〇、. To prevent vibration.

Next, the operation of the linear compressor of this embodiment will be described.

First, when the coil 53 of the fixed unit 50 is energized, a thrust proportional to the current is generated between the coil 53 and the permanent magnet 41 of the movable unit 4 according to Fleming's left-hand rule. Due to the generation of this thrust, a driving force that retreats along the axial direction acts on the movable portion 40. Since the cylindrical holding member 42 of the movable portion 40 is connected to the piston 2〇, the piston 2〇 smoothly retreats along its axial direction.

The alternating current in energizing the coil 53 is given as a sine wave, and forward and reverse thrusts are generated alternately in the linear motor unit. Then, the piston 2〇 reciprocates by the alternately generated forward and reverse thrusts.

The refrigerant is introduced from the suction pipe (not shown) into the closed container 1 容器 0 in FIG. The refrigerant introduced into the closed container 1〇〇 is assembled to the cylinder end face 11 from the suction side space of the head cover section 8〇 and enters the compression chamber 13 through a suction valve (not shown). The refrigerant is compressed by the piston 20, passes through a discharge valve (not shown) assembled to the cylinder end face 11, passes through a discharge side space of the head cover 80, and is discharged outward from a discharge pipe (not shown). Is discharged. The vibration of the cylinder 10 caused by the reciprocation of the piston 20 is damped by the plurality of coil springs 91 and 92. In a free-stroke linear compressor where the position of the piston 2 is determined by the operating pressure conditions and the balance of the additional power supplied to the linear motor, etc. The amplitude may change suddenly. As a result, the piston 2〇 is driven beyond the allowable stroke of the linear motor, and the piston 2〇 may collide with the cylinder end surface 11 1.

The compression-chamber-side coil spring 15 is assembled such that the position of the piston 20 in the most compressed state is the top dead center 29 of the piston 20. As a result, the piston 2〇 is mechanically restrained by the compression-chamber-side coil spring 15 and the piston amplitude of the free piston stroke can be regulated, so that the piston 2 ことが does not collide with the cylinder end face 11; The piston tip can be prevented from colliding with the cylinder end face against disturbance force such as when the amplitude of the piston suddenly changes.

In addition, by making the cross-sectional shape of the compression-chamber-side coil springs 15 and the anti-compression-chamber-side coil springs 30 into an oval or elliptical spring, the maximum force generated by the wire when the spring bends can be reduced compared to the round wire cross section. Because it can be lowered, the height of the coil spring can be reduced, the spring can be made compact, and the linear compressor can be downsized.

FIG. 2 is an enlarged view of a main part of a lifting operation in which the compression-chamber-side coil spring is a non-linear coil spring. The other configuration is the same as that of FIG. 1, and the description is omitted.

In the present embodiment, the non-linear coil spring 15 is constituted by an unequal pitch spring. Since uneven pitch springs have non-uniform pitches, as the deflection of the springs increases, more inter-wire bonding occurs and the effective number of turns decreases as compared to equal pitch springs. Therefore, as shown in Fig. 3, when the deflection is large, the spring load is increased with a non-linear load characteristic, the piston speed is absorbed, and the impact force of the piston on the cylinder end face 11 is reduced. It can reduce impact noise and obtain good durability.

FIG. 4 is an enlarged view of a main part showing another embodiment in which the compression chamber side coil spring is a non-linear coil spring. In this embodiment, the other configuration is the same as that of FIG.

In this embodiment, the non-linear coil spring 15 is constituted by a conical coil spring. In this embodiment, since the compression chamber-side coil spring 15 is a conical coil spring as described above, when the spring deflection becomes large, the same as the above-mentioned unequal pitch coil spring is obtained. The effect becomes more pronounced, and as shown in Fig. 5, when the deflection is large, the spring load increases greatly.As the piston speed approaches the top dead center, it works effectively as a brake that absorbs the piston speed, and the cylinder end surface The impact force of the piston can be reduced, the impact noise can be reduced, and the reliability can be improved.

Here, the compression chamber side coil spring 15 shown in FIG. 1 is assumed to have a spring constant weaker than that of the anti-compression chamber side coil spring 30. In particular, the constant k 1 of the coil spring 15 which is the coil spring on the compression chamber side, and the spring constant k 2 of the coil spring 3 で which is the coil spring on the side of the non-compression chamber, the amplitude of the piston a, When the offset amount is pushed to the anti-compression chamber side by the applied gas force, the relational expression of approximately k1X (a +) = k2X (a-) is established.

Fig. 6 shows the correlation between the coil springs. At the time of assembly, a preload FO is added to compress the coil springs in order to use both coil springs 15 and 3 加える as compression springs. During operation, the piston is offset from the piston mounting position to the compression chamber side by the gas force Fg of the compression chamber from the piston amplitude center position. The amount of deflection x 1 and x 2 of each coil spring 15 and 3〇 increases the amount of deflection x 1 of the compression chamber side coil spring 15 with a small spring constant. The predetermined coil spring constant is determined from the sum of k 1 + k 2 from the driving frequency of the linear compressor, and the necessary piston stroke 2 a and offset amount α can be set by the operating pressure condition and the bore diameter of the piston 20. By selecting each spring constant based on these dimensions so as to satisfy the above relational expression, the piston amplitude center position 運転 during operation can be adjusted to the compression chamber side coil spring 15 and the counter compression chamber side coil spring 3 ばね. Is approximately halfway between the maximum deflection of the piston and the maximum deflection of the piston, which is determined by the design. it can. Therefore, the coil spring can be made compact, and the size of the linear compressor can be reduced.

As described above, the piston 20 is mechanically compressed by the compression-chamber-side coil spring 15 when compressed most by the compression chamber-side coil spring 15 against external impact force such as during operation with a large stroke or during transportation. Since the piston amplitude can be regulated under the restraint, the piston end can be prevented from colliding with the cylinder end face, and a highly reliable compressor can be realized. Further, the compression chamber side coil springs 15 may be unequal pitch springs or conical coil springs. As a result, compared to a compression coil spring, when the piston approaches the top dead center, the spring load increases, it acts as a brake that absorbs the piston speed, and the piston impact force on the cylinder end face can be reduced, resulting in an impact sound. And good durability can be obtained.

In addition, each coil spring constant is approximately changed to the compression chamber side coil so that the relational expression of k 1 X (a + c 2 k 2 X (a—) holds). By reducing the length, it is possible to reduce the size of the linear compressor by reducing the size of the coil spring because no extra spring deflection is required.

Also, by making the coil spring into an oval or elliptical cross section, the maximum force generated by the wire when the spring is deflected can be reduced compared to the round wire cross section, and the coil spring height can be reduced. In addition, the coil spring can be made compact, and the size of the linear compressor can be reduced.

In the above embodiment, a linear compressor having a compression mechanism using gas has been described. However, a pressure feed mechanism for liquid other than gas may be used.

Further, in the above-mentioned embodiment, although the refrigerant used is not particularly described, it is preferable to use a refrigerant mainly composed of carbon dioxide. Under high pressure differential refrigerant, lubrication becomes severe. C〇2) Under the refrigerant, it is much more efficient and higher reliability than other compressors. Industrial applicability

According to the invention, when the compression chamber-side coil spring is most compressed, a clearance is secured between the piston end face and the cylinder end face, so that a pressure change during operation and a disturbance force at the time of transportation, etc. Even when the piston suddenly changes, the piston amplitude is regulated by the compression chamber side coil spring when the piston amplitude increases, so that collision between the piston tip and the cylinder end face can be avoided, and reliability can be improved.

According to the invention, by using a non-linear coil spring for the compression chamber side coil spring, the spring load increases as the deflection increases. Therefore, since the piston speed approaching the top dead center is absorbed, the effect of reducing the impact force can be expected.

According to the invention, the non-linear coil spring is formed as an unequal-pitch coil spring. As the deflection is increased, the inter-wire adhesion is more improved as compared with the equal-pitch coil spring. As a result, the effective number of turns decreases and the spring load increases, so the piston speed approaching top dead center is absorbed, the impact force is reduced, and good durability is obtained.

According to the invention, when the compression chamber-side coil spring is a conical coil spring, when the spring deflection increases, the same effect of the unequal-pitch coil spring becomes more remarkable, and the spring load increases greatly. It works effectively as a brake that absorbs the velocity of the piston approaching the point, can reduce the impact force of the piston, reduce ffj sound, and increase reliability.

Further, according to the invention, by setting the coil spring constant on the compression chamber side small and increasing the coil spring constant on the non-compression chamber side, it is determined from the compressor design as compared with the case where the coil spring constants on the compression chamber side and the non-compression side are the same. The maximum amount of deflection of the spring can be suppressed for the maximum piston amplitude obtained. Therefore, the coil spring can be reduced in size, and the linear compressor can be reduced in size.

According to the invention, the coil spring constant is determined so that the relational expression of kX (a + α) '= k2X (a-) is substantially satisfied. Since the center of amplitude can be accurately adjusted so that it is almost halfway between the maximum deflection of the coil spring, the maximum deflection of the spring can be further reduced, making the coil spring more compact. The size of the linear compressor can be reduced. According to the invention, the coil spring has an oval or elliptical cross-sectional shape, so that the maximum force generated in the wire at the time of spring deflection is reduced and the coil spring height is reduced as compared with a round wire cross section. Therefore, the coil spring can be made compact, and the size of the linear compressor can be reduced.

According to the invention, refrigerants containing carbon dioxide as a main component are used, and lubrication becomes severe with high differential pressure refrigerants. And high reliability can be obtained.

Claims

The scope of the claims

1 A compression mechanism for compressing gas and a linear motor for operating the compression mechanism are provided in a closed container, the compression mechanism has a cylinder and a piston, and has a compression chamber for performing gas compression in the cylinder. The linear motor has a fixed portion connected to the cylinder and a movable portion connected to the piston, and has one end pressed to the biston or the movable portion and the other end to the cylinder or the cylinder on the compression chamber side. A compression chamber-side coil spring that presses against a fixed portion) A spring and one end presses against the piston or the movable portion, and the other end presses against the cylinder or the fixed portion on the anti-compression chamber side. Thus, in the linear compressor in which the piston is movably supported in the axial direction, a gap is secured between the piston end face and the cylinder end face when the compression chamber-side coil spring is compressed most. Linear compressor, characterized in that the.

2. The linear compressor according to claim 1, wherein the compression chamber side coil spring is a non-linear coil spring.

3. The linear compressor according to claim 2, wherein the non-linear coil spring is an unequal pitch coil spring.

4. The linear compressor according to claim 2, wherein the non-linear coil spring is a conical coil spring.

5 A compression mechanism for compressing gas and a linear motor for operating this compression mechanism are provided in a closed container, the compression mechanism has a cylinder and a piston, and has a compression chamber for performing gas compression in the cylinder. The linear motor has a fixed portion connected to the cylinder and a movable portion connected to the piston. One end is pressed against the piston or the movable portion, and the other end is connected to the cylinder or the cylinder on the compression chamber side. A compression chamber-side coil spring that presses against the fixed portion and an anti-compression chamber-side coil spring that presses one end against the piston or the movable portion and presses the other end against the cylinder or the fixed portion on the anti-compression chamber side. In the linear compressor, wherein the piston is movably supported in the axial direction, the compression chamber side coil spring constant is smaller than the anti-compression chamber side coil spring constant. Machine.

6 The amplitude of the piston is a, and the amount of offset of the piston to the non-compression chamber side by the gas force applied from the compression chamber during operation is Assuming that the spring constant is k 1 and the anti-compression chamber side coil spring constant is k 2, the coil spring constant k is set such that a relational expression of approximately k 1 X (a ten) 2 k 2 X (a—) holds. The linear compressor according to claim 5, wherein 1, k2 is determined.

7. The linear compressor according to claims 1 to 6, wherein the compression chamber side coil spring or the anti-compression chamber side coil spring has an oval or elliptical cross section.

8. The linear compressor according to claim 1, wherein the linear compressor is operated using a refrigerant containing carbon dioxide as a main component.