JP2000002181A - Linear compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure durability, wear resistance and sealing property without using lubricating oil or by using an extremely small amount of lubricating oil by forming a piston and a cylinder by an aluminum material and making a coefficient of thermal expansion of the piston than that of the cylinder. SOLUTION: By performing energizing to a stator 31 of a linear motor 25, a piston 28 is moved rightward and coolant introduced from a suction port 40 is introduced into a compression chamber 24 via a suction valve 28'. By stopping energizing to the stator 31, the piston 28 is moved leftward by a resonance spring 32, and coolant within the compression chamber 24 is compressed and is discharged from a discharge port 41. At this time, the piston 28 and a cylinder 27 are made of aluminum and a coefficient of thermal expansion of the piston 28 is made larger than that of the cylinder 27. As a result, a gap between the piston 28 and the cylinder 27 at the time of cooling is made large and a high speed starting is made possible, and after a warming up, the gap is reduced and compression efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear compressor for compressing and discharging a refrigerant by reciprocating a piston slidably supported by a cylinder by a linear motor, and in particular, uses an oilless or lubricant. It relates to a small amount of oil-poor linear compressor.

[0002]

2. Description of the Related Art As a linear compressor for compressing and discharging a refrigerant by reciprocating a piston slidably supported by a cylinder in the axial direction thereof, a linear vibration actuator (Liner Oscillator Actuator) is known.
or, abbreviated as LOA). Among them, a magnetically movable LOA using magnetic force is often used for a compressor. There are also various types of this type of magnetically movable LOA, for example,
There are a radial type, an axial type, a magnetic path independent type, a magnetic path common type and the like.

FIG. 2 is a schematic view of a linear compressor 200a for explaining a schematic structure of a magnetically movable LOA. The cylinder 2a held in the closed container 23a has a piston 2
8a is slidably supported along its axial direction. A magnet 30a is fixed to the piston 28a. A stator 31a embedded in the outer yoke 38a is provided at a position facing the magnet 30a.
A suction pipe 40a and a discharge pipe 35a are connected to the compression chamber 24a formed by the cylinder 27a and the piston 28a, and a discharge valve 43 is provided in the discharge pipe 35a. The piston 28a is elastically supported by the support spring 32a. In FIG. 2, the linear motor 25a including the outer yoke 38a, the stator 31a, and the magnet 30a is intermittently energized so that the piston 28a
Reciprocates in the axial direction, and refrigerant is sucked and compressed in the compression chamber 24a. Each component of the conventional linear compressor 200a is mainly made of an iron material.

[0004]

Incidentally, it is desirable to use an HC-based refrigerant as a refrigerant for a compressor in order to prevent ozone layer destruction and global warming. However, HC
Since the system refrigerant is flammable, it is necessary to minimize the amount of filling. And in order to reduce the amount of refrigerant to be enclosed,
It is effective to minimize the amount of lubricating oil in which the refrigerant is dissolved or to use no lubricating oil at all. Here, paying attention to the structure of the conventional linear compressor, since the cylinder 27a and the piston 28a slide in contact with each other, it is necessary to use lubricating oil, but other members are not necessarily in contact with each other. No moving action is required. Therefore, the cylinder 27a
If the sliding surface between the piston 28a and the piston 28a can be configured to be slidable without using lubricating oil or by using only a very small amount of lubricating oil, the amount of the enclosed refrigerant can be reduced. Further, if the lubricating oil is not used or can be extremely small, there is no need to consider the reaction and characteristics of the refrigerant to be used with the lubricating oil. Therefore, the range of selection of usable refrigerants is widened, and high-efficiency refrigerants can be used.

Accordingly, an object of the present invention is to provide a linear compressor that can ensure durability, abrasion resistance, and sealing performance without using a lubricating oil or with a very small amount of lubricating oil.

[0006]

According to the first aspect of the present invention, there is provided a linear compressor according to the present invention, wherein a cylinder, a piston slidably supported by the cylinder along an axial direction thereof, and the piston are moved. A linear compressor having a linear motor and configured to discharge a compressed refrigerant by compressing a refrigerant introduced into the cylinder, wherein the piston and the cylinder are formed of an aluminum material, Wherein the coefficient of thermal expansion is larger than the coefficient of thermal expansion of the cylinder. According to a second aspect of the present invention, in the linear compressor according to the first aspect, the silicon content of the cylinder is larger than the silicon content of the piston. 4. The linear compressor according to claim 3, wherein the linear compressor includes a cylinder, a piston slidably supported by the cylinder along an axial direction thereof, and a linear motor that moves the piston. A linear compressor configured to compress a refrigerant introduced into the compressor and discharge a compressed refrigerant, wherein the piston and the cylinder are formed of an aluminum material, and thermal expansion coefficients of the piston and the cylinder are substantially equal. It is characterized by doing. The linear compressor according to the present invention according to claim 4, comprising: a cylinder; a piston slidably supported by the cylinder along an axial direction thereof; and a linear motor that moves the piston. A linear compressor configured to compress a refrigerant introduced therein and discharge a compressed refrigerant, wherein Ni-P-B or Ni-CO-P / Si3N4 particles are formed on a surface of the piston or the cylinder. Are dispersed and subjected to a surface treatment. The linear compressor according to the present invention according to claim 5, comprising: a cylinder; a piston slidably supported by the cylinder along an axial direction thereof; and a linear motor for moving the piston. A linear compressor configured to compress the refrigerant introduced into and discharge the compressed refrigerant,
An alumite treatment and a dispersion treatment of MOS2 particles are performed on the surface of the piston or the cylinder.
The linear compressor according to the present invention according to claim 6, comprising: a cylinder; a piston slidably supported by the cylinder along an axial direction thereof; and a linear motor that moves the piston. A linear compressor configured to compress a refrigerant introduced into the compressor and discharge a compressed refrigerant, wherein a surface of the piston or the cylinder includes Ti.
It is characterized by performing AlN or diamond-like carbon (DLC) treatment. The linear compressor according to the present invention according to claim 7, comprising: a cylinder; a piston slidably supported by the cylinder along an axial direction thereof; and a linear motor for moving the piston. A linear compressor configured to compress a refrigerant introduced therein and discharge a compressed refrigerant, wherein a porous ceramic layer is formed on the piston or the cylinder. The linear compressor according to the present invention according to claim 8, further comprising: a cylinder, a piston slidably supported by the cylinder along an axial direction thereof, and a linear motor that moves the piston. A linear compressor configured to compress a refrigerant introduced therein and discharge a compressed refrigerant, wherein a dry coating is applied to the piston or the cylinder. The linear compressor of the present invention according to claim 9 has a cylinder, a piston slidably supported by the cylinder along the axial direction thereof, and a linear motor that moves the piston,
A linear compressor configured to compress a refrigerant introduced into the cylinder and discharge a compressed refrigerant, wherein the piston or the cylinder is formed of sintered aluminum powder. The linear compressor of the present invention according to claim 10, a cylinder, and a piston slidably supported by the cylinder along the axial direction thereof,
A linear motor having a linear motor for moving the piston, and configured to compress the refrigerant introduced into the cylinder and discharge the compressed refrigerant, wherein the piston or the cylinder is densely sintered. It is made of iron. The linear compressor according to claim 11, wherein the cylinder includes a cylinder, a piston slidably supported by the cylinder along an axial direction thereof, and a linear motor that moves the piston. A linear compressor configured to compress a refrigerant introduced therein and discharge a compressed refrigerant, wherein liquid crystal is used as a lubricant. According to a twelfth aspect of the present invention, in the linear compressor according to any one of the first to eleventh aspects, the linear motor is embedded in the outer yoke fixed to the cylinder and the outer yoke. A stator,
An inner yoke fixed to the piston and a magnet fixed to the inner yoke and opposed to the stator are provided.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A linear compressor according to an embodiment of the present invention includes a cylinder, a piston slidably supported by the cylinder along the axial direction thereof, and a linear motor for moving the piston. I have. The linear motor is composed of an outer yoke fixed to the cylinder, a stator embedded in the outer yoke, an inner yoke fixed to the piston, and a magnet fixed to the inner yoke and arranged to face the stator. Be composed.

In the first embodiment of the present invention, the piston and the cylinder are formed of aluminum material, and the coefficient of thermal expansion of the piston is made larger than the coefficient of thermal expansion of the cylinder. As shown in the embodiment, the silicon content is changed. in this way,
By setting the coefficient of thermal expansion of the piston to be larger than the coefficient of thermal expansion of the cylinder, the gap between the piston and the cylinder can be increased. Therefore, for example,
When the temperature of the piston or the cylinder is low when the temperature is low, friction caused by sliding between the piston and the cylinder can be reduced, and high-speed starting can be performed. Also, after the start-up operation, the temperature of the piston and cylinder has risen,
The gap between the piston and the cylinder becomes smaller, and high-efficiency operation becomes possible.

In a third embodiment of the present invention, the piston and the cylinder are formed of aluminum material, and the piston and the cylinder have substantially equal thermal expansion coefficients. By making the thermal expansion coefficients of the piston and cylinder approximately equal in this way, the gap between the piston and cylinder is constant even when the piston or cylinder is cold or when the temperature rises. Even if a change occurs, highly efficient operation can be performed.

[0010] In a fourth embodiment of the present invention, Ni-P-B or Ni-
CO-P / Si3N4 particles are dispersed. In a fifth embodiment of the present invention, the surface of a piston or a cylinder is subjected to alumite treatment and MOS2 particle dispersion treatment. The surface of the piston or cylinder is subjected to TiAlN or diamond-like carbon (DLC) treatment. By performing surface treatment on the piston or cylinder as in the fourth to sixth embodiments, the durability is improved, and the piston or the cylinder can be operated without using lubricating oil or with very little lubricating oil. Also,
By performing the TiAlN or DLC treatment, the effect of lowering the friction coefficient is obtained, the efficiency is improved, and the performance can be improved.

In a seventh embodiment of the present invention, a porous ceramic layer is formed on a piston or a cylinder. As described above, according to the present embodiment, since the lubricating oil is held by the porous ceramic layer, the operation can be performed with an extremely small amount of lubricating oil.

In an eighth embodiment of the present invention, dry coating is performed on a piston or a cylinder. As described above, according to the present embodiment, the initial conformability is improved by the dry coating, and particularly, the operation at the time of starting can be smoothly performed.

In a ninth embodiment of the present invention, the piston or the cylinder is formed from sintered aluminum powder. As described above, according to the present embodiment, since the piston and the cylinder are porous, a large amount of lubricating oil can be held in the piston and the cylinder, so that operation with a small amount of lubricating oil is possible.

In a tenth embodiment of the present invention, the piston or the cylinder is made of high-density sintered iron. As described above, according to the present embodiment, since there are a number of independent holes on the surfaces of the piston and the cylinder, lubricating oil is retained on the surfaces of the piston and the cylinder, and hydraulic pressure is generated during sliding. Therefore, operation with extremely small amount of lubricating oil becomes possible.

The eleventh embodiment of the present invention uses a liquid crystal as a lubricant. As described above, according to the present embodiment, the operation can be performed without using the lubricating oil by using the liquid crystal as the lubricant.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the linear compressor according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the structure of the linear compressor 200. The linear compressor 200 includes a cylinder 27, a piston 28, a linear motor 25, a spring mechanism 4
2. It comprises a discharge pipe 35 and a sealed container 23 for accommodating them.

The linear motor 25 includes an outer yoke 38
And a magnet 30 disposed at a position facing the stator 31 and fixed to an inner yoke 39, and connected to an alternating current supply source (not shown).

The cylinder 27 has a cylinder hole 27 'for slidably supporting a piston 28 and a flange portion 27 ". The outer yoke 3 is formed in the flange portion 27".
8 are connected. On the other hand, the piston 28 has an opening 28 'for opening and closing the suction valve 37 at the front end thereof and a flange 28 "at the rear end. An inner yoke 39 is connected to the flange 28". The inner yoke 39 is slidably supported on the outer periphery of the cylinder 27, and holds the magnet 30 as described above. The piston 28 has a suction hole 36 for introducing a refrigerant.
Having. A seal member 2 is provided on the outer periphery of the piston 28.
9 is fitted to provide a seal between the cylinder 27 and the piston 28.

The front side of the cylinder 27 is closed by a discharge valve support 33, and a compression chamber 24 is formed between the cylinder 27 and the front end surface of the piston 28. A discharge valve (not shown) is housed in the center of the discharge valve support 33.
The discharge valve support 33 is connected to a spiral discharge pipe 35 via a muffler 34.

The resonance spring 32 of the spring mechanism 42 is fixed to the rear ends of the outer yoke 38 and the piston 28.
The resonance spring 32 is connected to the closed container 23 via the support spring 26.
Is held. A support spring 26 ′ held on the front side of the sealed container 23 holds the muffler 34 and the like. A suction port 40 is formed at the rear end of the closed container 23. A discharge port 4 connected to a discharge pipe 35 is provided on the front side of the closed container 23.
1 is formed.

Next, the operation of the linear compressor having the above structure will be described. When the stator 31 of the linear motor 25 is energized, an eddy current flows between the stator 31 and the magnet 30. As a result, the piston 28 moves in a direction opposite to the discharge pipe 35 side (that is, moves backward). Therefore, the refrigerant introduced from the suction port 40 and the suction hole 36 opens the suction valve 28 ′ and is introduced into the compression chamber 24. Note that energy is stored in the resonance spring 32 and the support spring 26 by the retreat of the piston 28.

When the current supply to the stator 31 is stopped in this state, the energy stored in the resonance spring 32 and the like is released, and the piston 28 moves in the direction of the discharge pipe 35 (that is, moves forward). As described above, the suction valve 37 is closed, and the refrigerant in the compression chamber 24 is compressed. The compressed refrigerant pushes and opens a discharge valve provided at the center of the discharge valve support 33, is discharged into the muffler 34 and is muffled, flows through the spiral discharge pipe 35, and flows out of the discharge port 41. It is discharged outside. The compression capacity of the linear compressor 200 is determined by the release of power supply to the linear motor 25, the input of power supply, and the like. In addition, since the vibration generated at the time of suction and discharge is suppressed by the resonance spring 32 and the support springs 26 and 26 ', the overall vibration of the linear compressor is suppressed and the noise is reduced. The reason why the discharge pipe 35 is formed in a spiral shape is to absorb the movement of the cylinder 27 due to the movement of the piston 28.

Next, a description will be given of a specific embodiment of the material of the cylinder 27 and the piston, which are main components of the linear compressor 200, and the surface treatment thereof. First, the cylinder 27
And the piston 28 is formed of an aluminum material. Thereby, the weight can be reduced first. In this case, the coefficient of thermal expansion of the piston 28 is made larger than the coefficient of thermal expansion of the cylinder.
Specifically, for example, the content of silicon in the cylinder 27 is made larger than that in the piston 28. The means for changing the coefficient of thermal expansion is not limited to this specific example. By making the thermal expansion coefficient of the piston 28 larger than that of the cylinder 27, the gap between the outer surface of the piston 28 and the inner surface of the cylinder 27 when the linear compressor 200 is cold can be increased. Thus, piston 2
By increasing the gap between the outer surface of the cylinder 8 and the inner surface of the cylinder 27, high-speed starting can be performed, and at the time of heat, the gap becomes smaller, thereby improving the efficiency. On the other hand, the piston 28
By making the thermal expansion coefficients of the piston 27 and the cylinder 27 substantially the same, the gap between the outer surface of the piston 28 and the inner surface of the cylinder 27 can be reduced. By thus reducing the gap between the outer surface of the piston 28 and the inner surface of the cylinder 27, high efficiency can be maintained even when the thermal conditions change.

In the next embodiment, a cylinder 27 and a piston 28
Is subjected to a surface treatment. This surface treatment may be applied to either the cylinder 27 or the piston 28, but the efficiency is further increased by applying the surface treatment to both. In this case, the material of the base material of the cylinder 27 and the piston 28 is not limited. As a specific example of the surface treatment, detailed description is omitted because each is a known technique, for example,
Ni-P-B, Ni-CO-P / Si3M4 particles are dispersed on the surface, alumite treatment, MOS2 particle dispersion, TiAlN, DLC coating treatment, and the like. By performing this surface treatment, the durability can be greatly improved, and oilless and oil poor inside the compressor can be achieved. Further, by performing the TiAlN or DLC treatment, there is an effect of reducing the friction coefficient, and the efficiency is improved and the performance can be improved.

In the next embodiment, a porous ceramic layer is formed on the contact engagement surface side of the piston 28 and the cylinder 27, but the efficiency is further increased by applying both layers. Due to the formation of the porous ceramic layer, the oil film holding power is improved, and oil poor can be realized.

In the following embodiment, a solid lubricating film is applied to both or one of the contact sliding surfaces of the piston 28 and the cylinder 27. By applying such a dry coating, especially the initial conformability can be improved.

In the next embodiment, one or both of the piston 28 and the cylinder 27 are formed from sintered aluminum powder. As described above, the piston 28 and the cylinder 28 are formed to be porous, and it is easy to realize oil poor.

In the next embodiment, one or both of the piston 28 and the cylinder 27 are formed of high-density sintered iron. When high-density sintered iron is used, the oil film holding power can be improved by appropriately setting the density, the average pore diameter, the distribution and the area ratio. This has the effect of improving durability and reducing weight. Here, specific characteristics of the high-density sintered iron used in the present invention and a method for manufacturing the same will be briefly described. First, the high-density sintered iron to be used is composed of independent pores, the density of which is about 7.3 or more, the average pore diameter is 10 μm or less in a circle equivalent diameter, and the frequency distribution of the pore diameter is a circle equivalent. It is preferable to use one having a frequency of 10% or less in diameter and 10% or less and an area ratio of 5% or less. Also,
The production method is usually one-time sintering after pressing. In particular, in the case of the present invention, two-time sintering is preferable. That is, sintering is performed after pressing, and further pressing is performed to perform second sintering. In addition, warm molding is performed in a state where the entire mold is heated.

In the next embodiment, one or both of the piston 28 and the cylinder 27 are formed of an inexpensive iron-based material, and liquid crystal is used as a lubricant in an oil poor. As such a liquid crystal, there is a thermotropic liquid crystal.
The thermotropic liquid crystal is a mixed liquid crystal mainly composed of biphenyl-based and ester-based substances, and assumes a liquid crystal state in a temperature range between a liquid phase and a solid phase. Thermotropic liquid crystals include a nematic liquid crystal that is generally used for liquid crystal displays, and a smectic liquid crystal that has higher crystallinity than the nematic liquid crystal. As described above, the sealing performance is improved, and the effect of higher efficiency can be obtained.

In the above description, the linear compressor is shown in FIG.
However, the present invention is not limited to this embodiment, and may have the configuration shown in FIG. 2 showing the general structure of the linear compressor or another configuration.

[0031]

According to the present invention, the compressor is driven to rotate with high efficiency, and durability, wear resistance, weight reduction,
Improved oil film retention and sealability, high-speed starting,
In addition, an oil-less or oil-poor compressor can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the overall structure of a linear compressor according to the present invention.

FIG. 2 is a schematic diagram showing a schematic structure of a linear compressor.

[Explanation of symbols]

 23 Closed Vessel 24 Compression Chamber 25 Linear Motor 26 Support Spring 26 'Support Spring 27 Cylinder 28 Piston 29 Seal Member 30 Magnet 31 Stator 32 Resonance Spring 33 Discharge Valve Support 34 Muffler 35 Discharge Pipe 36 Suction Hole 37 Suction Valve 38 Outer Yoke 39 Inner yoke 40 Suction port 41 Discharge port 42 Spring mechanism 200 Linear compressor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sadao Kawahara 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 3H003 AA02 AC03 AD01 BC03 BD02

Claims (12)

[Claims] A cylinder, a piston slidably supported by the cylinder along an axial direction thereof, and a linear motor for moving the piston, for compressing a refrigerant introduced into the cylinder. Wherein the piston and the cylinder are formed of an aluminum material, and a coefficient of thermal expansion of the piston is larger than a coefficient of thermal expansion of the cylinder. Linear compressor. 2. The linear compressor according to claim 1, wherein a silicon content of the cylinder is larger than a silicon content of the piston. 3. A cylinder comprising: a cylinder; a piston slidably supported by the cylinder along an axial direction thereof; and a linear motor for moving the piston, and compresses a refrigerant introduced into the cylinder. A linear compressor configured to discharge a compressed refrigerant by using a piston and the cylinder formed of aluminum material, wherein the piston and the cylinder have substantially equal thermal expansion coefficients. . 4. A cylinder comprising: a cylinder; a piston slidably supported by the cylinder along the axial direction thereof; and a linear motor for moving the piston, for compressing a refrigerant introduced into the cylinder. A linear compressor configured to discharge a compressed refrigerant through the piston or the cylinder, wherein Ni-P-B or Ni-CO-P
/ Linear compressor characterized by dispersing Si3N4 particles and performing surface treatment. 5. A cylinder comprising: a cylinder; a piston slidably supported by the cylinder along an axial direction thereof; and a linear motor for moving the piston, and compressing a refrigerant introduced into the cylinder. A linear compressor configured to discharge a compressed refrigerant through an alumite process and a dispersion process of MOS2 particles on a surface of the piston or the cylinder. 6. A cylinder comprising: a cylinder; a piston slidably supported by the cylinder along an axial direction thereof; and a linear motor for moving the piston, and compressing a refrigerant introduced into the cylinder. A linear compressor configured to discharge a compressed refrigerant by applying TiAlN or diamond-like carbon (DLC) treatment to a surface of the piston or the cylinder. 7. A cylinder comprising: a cylinder; a piston slidably supported by the cylinder along the axial direction thereof; and a linear motor for moving the piston, and compresses a refrigerant introduced into the cylinder. A linear compressor configured to discharge a compressed refrigerant through the piston or the cylinder, wherein a porous ceramic layer is formed on the piston or the cylinder. 8. A cylinder having a cylinder, a piston slidably supported by the cylinder along the axial direction thereof, and a linear motor for moving the piston, wherein the linear motor compresses a refrigerant introduced into the cylinder. A linear compressor configured to discharge compressed refrigerant by dry coating, wherein the piston or the cylinder is dry-coated. 9. It has a cylinder, a piston slidably supported by the cylinder along the axial direction thereof, and a linear motor for moving the piston, and compresses a refrigerant introduced into the cylinder. Wherein the piston or the cylinder is formed of sintered aluminum powder. 10. A cylinder comprising: a cylinder; a piston slidably supported by the cylinder along the axial direction thereof; and a linear motor for moving the piston, for compressing a refrigerant introduced into the cylinder. A linear compressor configured to discharge compressed refrigerant through the piston, wherein the piston or the cylinder is made of high-density sintered iron. 11. A cylinder comprising: a cylinder; a piston slidably supported by the cylinder along an axial direction thereof; and a linear motor for moving the piston, for compressing a refrigerant introduced into the cylinder. A linear compressor configured to discharge compressed refrigerant by using a liquid crystal as a lubricant. 12. The linear motor includes an outer yoke fixed to the cylinder, a stator embedded in the outer yoke, an inner yoke fixed to the piston, and the linear motor fixed to the inner yoke. The linear compressor according to any one of claims 1 to 11, comprising a magnet arranged to face each other.