Compressor with different resin hardness layers

A compressor includes a compression mechanism and a resin layer including a stack of three or more layers formed on a whole area or a portion of at least one surface of at least one part of the compression mechanism. A hardness of a layer most distant from a base in the resin layer is smaller than a hardness of a layer closest to the base in the resin layer. A difference in hardness between two adjacent layers in the resin layer is smaller than a difference in hardness between the layer most distant from the base and the layer closest to the base.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. National stage application claims priority under 35 U.S.C. §119(a) to Japanese Patent Application Nos. 2010-289811, filed in Japan on Dec. 27, 2010, and 2010-289812, filed in Japan on Dec. 27, 2010, the entire contents of which are hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a compressor that compresses a refrigerant.

BACKGROUND ART

As a compressor, there has traditionally been a rotary compressor including a cylinder and a roller disposed inside the cylinder. In this rotary compressor, the roller is attached to a shaft that eccentrically rotates, and moves along the inner circumference surface of the cylinder with the rotation of the shaft.

In the rotary compressor, there is a minute gap between an end surface of a roller and an end plate member disposed to oppose this end surface, and between the outer circumference surface of the roller and the inner circumference surface of a cylinder, for the purpose of preventing seizure caused by sliding. The size of the gap is preferably as small as possible so as to prevent leakage of a refrigerant or lubricating oil. Even with such a gap however, the gap may close up and seizure may take place due to sliding, if the amount of thermal expansion of the roller is greater than that of the cylinder. Such a case may take place for example when the compressor is activated at a high speed.

Further, as a compressor other than the rotary compressor, there is a scroll compressor including a fixed scroll having a fixed-side wrap having a spiral shape, and a moveable scroll having a moveable-side wrap having a spiral shape that engages with the fixed-side wrap. In this scroll compressor, the moveable scroll is mounted to a shaft that eccentrically rotates, and circles with rotation of the moveable scroll.

In this scroll compressor, there is a small gap between an end surface of the wrap and a surface facing this end surface, and between a side surface of the wrap and a side surface (including a side surface of the other wrap) facing this side surface, for the purpose of preventing seizure caused by sliding. However, the gap closes up and seizure takes place, depending on the operation conditions.

To address the issue of seizure in the compressors, for example, Japanese Unexamined Patent Publication No. 275280/2006 (Tokukai 2006-275280) suggests a use of resin coating to improve the slidability. This allows prevention of seizure without enlarging the gap.

SUMMARY

Technical Problem

However, in addition to the above described problem of seizure, sliding movement also causes a problem that the efficiency of the compressor may deteriorated due to the frictional loss. The compressor of Japanese Unexamined Patent Publication No. 275280/2006 (Tokukai 2006-275280), with the resin coating, is able to prevent the seizure due to sliding; however, leaves the problem of deterioration in the efficiency of the compressor due to the frictional loss. Further, a resin coating layer swells by absorbing the refrigerant or the lubricating oil. Therefore, there is a possibility that the gap may close up not only in cases of activating the compressor at high speeds, but also in cases of ordinary operations. Therefore, when the surface of the resin coating slides in contact with the opposing member, the frictional loss increases due to the sliding.

A conceivable approach to restrain this problem is to reduce the hardness of the resin coating layer. If the resin coating layer is softened, the resin coating layer, even when sliding in contact with another member, is easily worn out or, if not, easily deformed. This reduces the surface pressure between contact surfaces, and thus reducing the frictional loss, and restrains deterioration in the efficiency of the compressor.

Meanwhile, if the hardness of the resin coating layer is reduced to the extent the hardness of the resin coating layer largely differs from that of a base such as roller, the adhesive strength between the resin coating layer and the base is weakened, and the resin coating layer is easily peeled from the base.

An object, of the present invention is to provide a compressor whose efficiency is restrained from deteriorating while a resin layer provided to an end surface of a piston or the like is prevented from separation from the base.

Solution to Problem

A first aspect of the present invention is a compressor, including a cylinder having a compression chamber and a blade housing in communication with the compression chamber; a first end plate member and a second end plate member which are disposed on both axial ends of the cylinder; and a piston disposed in the compression chamber and inside the blade housing, wherein the piston includes an annular roller disposed in the compression chamber and a blade extending from the outer circumference surface of the roller and disposed in the blade housing so as to be able to move forward and backward; a resin layer which is a stack of three or more layers is formed in a whole area or a portion of at least one of (1) an axial direction end surface of the piston; (2) a surface of the first end plate member, opposing to the axial direction end surface of the piston; (3) a surface of the second, end plate member, opposing to the axial direction end surface of the piston; (4) an outer circumference surface of the roller; and (5) an inner circumference surface of the compression chamber, the hardness of a layer most distant from a base in the resin layer is smaller than the hardness of a layer closest to the base in the resin layer, and a difference in the hardness of two adjacent layers in the resin layer is smaller than a difference between the hardness of the layer most distant from the base and the hardness of the layer closest to the base.

A second aspect of the present invention is a compressor, including: a cylinder having a compression chamber and a vane housing in communication with the compression chamber; a first end plate member and a second end plate member which are disposed on both axial ends of the cylinder; an annular roller disposed inside the compression chamber; and a vane having a leading end pressed against an outer circumference surface of the roller, which is disposed in the vane storage unit so as to be able to move forward and backward, wherein a resin layer which is a stack of three or more layers is formed in a whole area or a portion of at least one of (1) an axial direction end surface of the roller; (2) a surface of the first end plate member, opposing to the axial direction end surface of the roller; (3) a surface of the second end plate member, opposing to the axial direction end surface of the roller; (4) the outer circumference surface of the roller; and (5) an inner circumference surface of the compression chamber, the hardness of a layer most distant from a base in the resin layer is smaller than the hardness of a layer closest to the base in the resin layer, and a difference in the hardness of two adjacent layers in the resin layer is smaller than a difference between the hardness of the layer most distant, from the base and the hardness of the layer closest to the base.

A second aspect of the present invention is a compressor, including: a first scroll having a recess and a first wrap in a spiral shape, which projects from a bottom, surface of the recess; a second scroll having a recess and a second wrap in a spiral shape, which projects from a flat plate section, wherein the first scroll and the second scroll are closely located to each other so that the bottom surface of the recess and the flat plate section oppose to each other, and a side surface of the first wrap and a side surface of the second wrap oppose to each other, and wherein a resin layer which is a stack of three or more layers is formed in a whole area, or a portion of at least one of: (1) an end surface of the first wrap; (2) a surface opposing to the end surface of the first wrap on the flat plate section; (3) an end surface of the second wrap; (4) a surface opposing to the end surface of the second, wrap on the bottom surface of the recess; (5) the side surface of the first wrap; (6) the side surface of the second wrap; and (7) a circumference surface of the recess, the hardness of a layer most distant from a base in the resin layer is smaller than the hardness of a layer closest to the base in the resin layer, a difference in the hardness of two adjacent layers in the resin layer is smaller than a difference between the hardness of the layer most distant from the base and the hardness of the layer closest to the base.

In each of these compressors, the layer most distant from the base in the resin layer is soft. In cases of high-speed activation of the compressor or in cases where the compressor is operated under conditions such that the temperature of the refrigerant ejected significantly differs from the temperature of the incoming refrigerant, the amount of thermal expansion of the piston may be greater than that of the cylinder. This may lead to a problem that the resin layer swells by absorbing the lubricating oil, thus causing the layer most distant from the base to slide in contact with another member. However, even in such a case, the layer most distant from the base is easily worn out or, if not, easily deformed. This reduces the surface pressure between the contact surfaces, thus reducing the frictional loss, and restrains deterioration in the efficiency of the compressor. Further, by making the hardness of the layer closest to the base greater than that of the layer most distant from the base, the hardness of the layer closest to the base is approximated to the hardness of the base. This improves the adhesive strength between the resin layer and the base.

To achieve the above described effects, the hardness of the layer most distant from the base needs to made smaller than the hardness of the base. However, when the resin layer is structured by two layers, the difference between the hardness of the layer most distant from the base and that of the layer closest to the base becomes large, which may cause separation of the layer most distant from the base. In view of this problem, in each of the above compressors, the resin layer is structured by three or more layers, and a hardness differential of two adjacent layers is kept within a range smaller than a hardness differential between the layer most distant from the base and the layer closest to the base. This reduces the frictional loss, while improving the adhesive strength between the resin layer and the base, thereby preventing separation of the resin layer.

A fourth aspect of the present invention is the compressor of any one of the first to the third aspect adapted so that, among the three or more layers, the layer most distant from the base does not contain the anti-swelling agent.

Since the resin layer in this compressor contains the anti-swelling agent, the resin layer is kept from swelling by absorbing an oil or a refrigerant. Further, since the layer most distant from the base does not contain the anti-swelling agent, the anti-swelling agent does not abut the other member, even when the surface of the resin layer slides in contact with the other member. Therefore, as compared with a case where the layer most distant from the base contains an anti-swelling agent, the frictional loss is reduced while restraining deterioration in the efficiency of the compressor.

A fifth aspect of the present invention is the compressor of any one of the first to the fourth aspect adapted so that among the three or more layers, the layer closest to the base does not contain the anti-swelling agent.

Since the resin layer in this compressor contains the anti-swelling agent, the resin layer is kept from swelling by absorbing an oil or a refrigerant. Further, since the layer closest to the base does not contain the anti-swelling agent, weakening of the adhesive strength between the resin layer and the base, which is attributed to the anti-swelling agent, will not take place. Thus, unlike a case where the layer closest to the base contains the anti-swelling agent, it is possible to restrain separation of the resin layer from the base.

A sixth aspect of the present invention is the compressor of any one of the first to the fifth aspect adapted so that the hardness of each of the three or more layers is such that, the more distant the layer is from the base, the less the hardness of the layer becomes.

In the resin layer of this compressor, which is structured by three or more layers, the hardness differential between layers is kept small. This more effectively prevents separation of each layer in the resin layer.

A seventh aspect of the present invention is the compressor of any one of the first to the sixth aspect adapted so that the thickness of the layer most distant from the base is not more than 50% of the thickness of the resin layer.

In the compressor, the thickness of the layer most distant from the base, i.e., the layer softer than the layer closest to the base, is not more than 50% of the thickness of the entire resin layer. This restrains the amount of resin layer worn out by dusts such as chips generated by wear-out, as compared with a case where the entire resin layer is made a soft layer. Therefore, damages to the resin layer are kept, small.

An eighth aspect of the present invention is the compressor of any one of the first to the seventh aspect adapted so that, in the resin layer, the hardness of the layer most distant, from the base is smaller than the hardness of the surface opposing to the resin layer.

In this compressor, the hardness of the layer structuring the surface of the resin layer (i.e., layer most distant from the base) is lower than the hardness of the opposing component. Therefore, when the resin layer slides in contact with the opposing contact, due to swelling or the like, the layer most distant from the base is easily worn out. As the result, the surface pressure generated at the slide portion is reduced. This reduces the frictional loss and restrains deterioration in the efficiency of the compressor.

A ninth aspect of the present invention is the compressor of any one of the first to the eighth aspect adapted so that the bend elastic constant of at least one of three or more layers constituting the resin layer is smaller than the Young's modulus of at least one of two members disposed so as to sandwich the resin layer.

In this compressor, the bend elastic constant of at least one of the layers structuring the resin layer is small. Therefore, when the resin layer slides in contact with the opposing member, due to swelling or the like, the resin layer is easily elastically deformed. As the result, the surface pressure generated at the slide portion is reduced. This reduces the frictional loss and restrains deterioration in the efficiency of the compressor.

Advantageous Effects of Invention

As hereinabove described, the present invention brings about the following effects.

In the first to third aspects of the present invention, the layer most distant from the base in the resin layer is soft. In cases of high-speed activation of the compressor or in cases where the compressor is operated under conditions such that the temperature of the refrigerant ejected significantly differs from the temperature of the incoming refrigerant, the amount of thermal expansion of the piston may be greater than that of the cylinder. This may lead to a problem that the resin layer swells by absorbing the refrigerant or the lubricating oil, thus causing the layer most distant from the base to slide in contact with another member. However, even in such a case, the layer most distant from the base is easily worn out or, if not, easily deformed. This reduces the surface pressure between the contact surfaces, thus reducing the frictional loss, and restrains deterioration in the efficiency of the compressor. Further, by making the hardness of the layer closest to the base greater than that of the layer most distant from the base, the hardness of the layer closest to the base is approximated to the hardness of the base. This improves the adhesive strength between the resin layer and the base.

To achieve the above described effects, the hardness of the layer most distant from the base needs to made smaller than the hardness of the base. However, when the resin layer is structured by two layers, the difference between the hardness of the layer most distant from the base and that of the layer closest to the base becomes large, which may cause separation of the layer most distant from the base. In view of this problem, in each of first to third aspects of the present invention, the resin layer is structured by three or more layers, and a hardness differential of two adjacent layers is kept within a range smaller than a hardness differential between the layer most distant from the base and the layer closest to the base. This reduces the frictional loss, while improving the adhesive strength between the resin layer and the base, thereby preventing separation of the resin layer.

Since the resin layer in the fourth aspect of the present invention contains the anti-swelling agent, the resin layer is kept from swelling by absorbing an oil or a refrigerant. Further, since the layer most distant from the base does not contain the anti-swelling agent, the anti-swelling agent does not abut the other member, even when the surface of the resin layer slides in contact with the other member. Therefore, as compared with a case where the layer most distant from the base contains an anti-swelling agent, the frictional loss is reduced while restraining deterioration in the efficiency of the compressor.

In the fifth aspect of the present invention, since the resin layer contains the anti-swelling agent, the resin layer is kept from swelling by absorbing an oil or a refrigerant. Further, since the layer closest to the base does not contain the anti-swelling agent, weakening of the adhesive strength between the resin layer and the base, which is attributed to the anti-swelling agent, will not take place. Thus, unlike a case where the layer closest to the base contains the anti-swelling agent, it is possible to restrain separation of the resin layer from the base.

In the resin layer of the sixth aspect, which is structured by three or more layers, the hardness differential between layers is kept small. This more effectively prevents separation of each layer in the resin layer.

In the seventh aspect, the thickness of the layer most distant, from the base, i.e., the layer softer than the layer closest to the base, is not more than 50% of the thickness of the entire resin layer. This restrains the amount of resin layer worn out by dusts such as chips generated by wear-out, as compared with a case where the entire resin layer is made a soft layer. Therefore, damages to the resin layer are kept small.

In the eighth aspect of the present invention, the hardness of the layer structuring the surface of the resin layer (i.e., layer most distant from the base) is lower than the hardness of the opposing component. Therefore, when the resin layer slides in contact with the opposing contact, due to swelling or the like, the layer most distant from the base is easily worn out. As the result, the surface pressure generated at the slide portion is reduced. This reduces the frictional loss and restrains deterioration in the efficiency of the compressor.

In the ninth aspect of the present invention, the bend elastic constant of at least one of the layers structuring the resin layer is small. Therefore, when the resin layer slides in contact with the opposing member, due to swelling or the like, the resin layer is easily elastically deformed. As the result, the surface pressure generated at the slide portion is reduced. This reduces the frictional loss and restrains deterioration in the efficiency of the compressor.

DESCRIPTION OF EMBODIMENTS

The following describes a first embodiment of the present invention. The present embodiment is an exemplary application of the present invention to a mono cylinder rotary compressor. As shown inFIG. 1, a compressor1of the present embodiment includes a closed casing2and a compressing structure10and a drive mechanism6disposed in the closed casing2. Note that hatching for indicating the cross section of the drive mechanism6is omitted inFIG. 1. This compressor1, which is for use in a refrigerating cycle such as an air conditioner, compresses a refrigerant (CO2 in the present embodiment) introduced from the inlet pipe fitting3and outputs the compressed refrigerant from the outlet pipe fitting4. The following description of the compressor1assumes the up/down direction ofFIG. 1is the vertical direction.

The closed casing2is a cylindrical container with its both ends closed. On top of the casing2is provided an outlet pipe fitting4for output ting the compressed refrigerant, a terminal5for supplying currency to a later-mentioned coil of a stator7bof the drive mechanism6. Note thatFIG. 1omits illustration of wiring connecting the coil and the terminal5. Further, on a side portion of the closed casing2is provided an inlet pipe fitting3for introducing the refrigerant to the compressor1. Further, below the closed casing2is stored a lubricating oil L which smoothens the operation of a slide portion of the compressing structure10. In the closed casing2, the drive mechanism6and the compressing structure10are disposed up and down, respectively.

The drive mechanism6is provided for driving the compressing structure10, and includes a motor7serving as a drive source, and a shaft8attached to the motor7.

The motor7includes a substantially annular stator7bwhich is fixed to the inner circumference surface of the closed casing2, and a rotor7adisposed on the radially inner side of the stator7bwith an air gap therebetween. The rotor7ahas a magnet (not shown), and the stator7bhas a coil. The motor7rotates the rotor7ausing the electromagnetic force generated by supplying of the currency to the coil. Further, the outer circumference surface of the stator7bis not entirely in close contact with the inner circumference surface of the closed casing2, i.e., a plurality of recesses (not shown) extending in the vertical direction and communicating the spaces above and below the motor7are provided along the outer circumference surface of the stator7b.

The shaft8is for transmitting the drive force of the motor7to the compressing structure10, and is fixed to the inner circumference surface of the rotor7ato rotate integrally with the rotor7a. Further, the shaft8has an eccentric portion8ain a position serve as a later-mentioned compression chamber31. The eccentric portion8ais formed in a cylindrical manner, and its shaft center is deviated from the rotation center of the shaft8. To this eccentric portion8ais mounted a later-mentioned roller41of the compressing structure10.

Further, inside a substantially lower half of the shaft8is formed a lubrication path8bextended, in the vertical direction.

At the lower end portion of the lubrication path8bis inserted a pump member (not shown) having a helical blade shape, which draws the lubricating oil L into the lubrication path8bwith rotation of the shaft8. Further, the shaft8has a plurality of outlet holes8cfor outputting the lubricating oil L inside the lubrication path8bto the outside the shaft8.

The compressing structure10includes a front head (first end plate member)20fixed to the inner circumference surface of the closed casing2, a muffler11disposed above the front head20, a cylinder30disposed, below the front head20, a piston40disposed inside the cylinder30, and a rear head (second end plate member)50disposed below the cylinder30. As shown inFIG. 2, the cylinder30is a substantially annular member with a compression chamber31formed, at its center portion. This is detailed later. The cylinder30is fixed to the lower side of the front head20by using a bolt, along with the rear head50. Note thatFIG. 2omits illustration of a bolt hole which is formed on the cylinder30.

As shown inFIG. 1andFIG. 3, the front head20is a substantially annular member, and its center portion has a bearing hole21into which the shaft8is rotatably inserted. The outer circumference surface of the front head20is fixed to the inner circumference surface of the closed casing2by means of spot welding or the like. The under surface of the front head20closes the upper end of the compression chamber31of the cylinder30. On the front head20is formed a discharge hole22which ejects a refrigerant compressed in the compression chamber31. The discharge hole22, when viewed in the vertical direction, is formed nearby a later-mentioned blade housing33in the cylinder30. On the top surface of the front head20is attached a valve structure which opens and closes the discharge hole22according to the pressure inside the compression chamber31. Illustration of this however is omitted. Further, at a portion of the front head20radially outside of the cylinder30, a plurality of oil-returning holes23are formed and aligned in the circumferential direction. The front head20is made of a metal material and example methods of manufacturing include sintering of metal powder, casting, and cutting.

The rear head50is a substantially annular member, and its center portion has a bearing hole51into which the shaft8is rotatably inserted. The rear head50closes the lower end of the compression chamber31of the cylinder30. The rear head50is made of a metal material and example methods of manufacturing include sintering of metal powder, casting, and cutting.

The muffler11is provided for the purpose of reducing the noise generated at the time of ejecting the refrigerant from the discharge hole22of the front head20. The muffler11is attached to the top surface of the front head20by using a bolt, and forms a muffler space M between the front head20and the muffler11. Further, the muffler11has a muffler discharge hole for discharging the refrigerant in the muffler space M.

As shown inFIG. 1andFIG. 2, in the cylinder30are formed the above-mentioned compression chamber31, a draw-in hole32for introducing the refrigerant, inside the compression chamber31, and a blade housing33. Note thatFIG. 2(a) is a cross sectional view taken along the line A-A ofFIG. 1, and the discharge hole22on the front head20is not supposed to be shown. However, for the sake of convenience, the discharge hole22is shown in the figure. The cylinder30is made of a metal material and example methods of manufacturing include sintering of metal powder, casting, and cutting.

The draw-in hole32extends in a radial direction of the cylinder30, and a leading end of the inlet pipe fitting3is inserted into the end portion (the end portion opposite to the compression chamber31) of the draw-in hole32.

The blade housing33penetrates the cylinder30in the vertical direction, and is in communication with the compression chamber31. The blade housing33extends in a radial direction of the compression chamber31. The blade housing33, when viewed in the vertical direction, is formed between the draw-in hole32and the discharge hole22of the front head20. Inside the blade housing33is a pair of bushes34. The pair of bushes34each has a shape such that a substantially cylindrical member is cut in half. Between the pair of bushes34is disposed a blade42. The pair of bushes34is capable of moving within the blade housing33, in the circumferential direction, while the blade42disposed, therebetween.

As shown inFIG. 4, the piston40has an annular roller41, and a blade42extended, radially outward from the outer circumference surface of the roller41. As shown inFIG. 2, the roller41is disposed in the compression chamber31, and is mounted to the outer circumference surface of the eccentric portion8aso that relative rotation is possible. The blade42is disposed between the pair of bushes34in the blade housing33and is capable of moving forward and backward.

As shown inFIG. 2(b) toFIG. 2(a), the space formed between the outer circumference surface of the roller41and the circumferential wall of the compression chamber31, while the blade42is relatively out of the compression chamber31of the blade housing33, is divided into a low pressure chamber31aand a high pressure chamber31bby the blade42.

TheFIG. 5(a) snows the compressor1at the time of shipment. As shown inFIG. 5(a), a vertical length H1of the piston40at the time of shipment is slightly smaller than a vertical length H2of the compression chamber31, and the difference is, for example, 5 to 15 μm. Further, the external diameter of the roller41is such that, while the roller41is mounted to the eccentric portion8a, a minute gap d1of approximately 5 to 30 μm, for example, is formed between the outer circumference surface of the roller41and the circumferential wall of the compression chamber31(the gap is hereinafter referred to as radial-directional gap d1).

As shown inFIG. 4,FIG. 5(a), andFIG. 6, the piston40of the present embodiment includes: a base43of the metal material, a resin layers44a,44bwhich are each a thin film, coating the surfaces of the base43. The outer shape of the base43constitutes substantially the outer shape of the piston40. The base43is made by sintering of metal powder, casting, cutting or the like, and the surface thereof is polished.

The resin layers44a,44bcoats the top surface and the under surface of the base43, respectively. That is, the resin layers44a,44bare formed on the upper and lower end surfaces of the piston, respectively. Further, the resin layers44a,44bare hardly swollen at the time of shipment of the compressor1(slightly swollen, or not at all swollen). The thickness of each of the resin layers44a,44bat this time is, for example, approximately 10 to 20 μm. Note that the thickness is not limited to the thickness.

As shown inFIG. 6(a) andFIG. 6(b), resin layers44a,44bare each a stack of four layers including a first layer closest to the base43, a second layer, a third layer, and a fourth layer stacked in this order on the outside of the first layer. The fourth layer is farthest among the four layers from, the base43. The second layer and the third layer are disposed between the first layer and the fourth layer, and connect the first layer and the fourth layer. The thickness t1of each of the first to third layers is the same and the thickness t2of the fourth layer is smaller than the thickness t1of each of the first to third, layers. The thickness t2of the fourth, layer is not more than 50% of the entire thickness T1(=3×t1+t2) of each of the resin layers44a,44b. Further, in each of the resin layers44a,44b, the second layer and the third layer are each a layer containing an anti-swelling agent which prevents the layer from swelling even when an oil or a refrigerant is absorbed. The first layer closest to the base43and the fourth layer most distant, from the base43on the other hand do not contain the anti-swelling agent. Therefore, the second layer and the third layer are restrained from swelling as compared with the first layer and the fourth layer. The anti-swelling agent may be for example aluminum (Al), alumina, silicon nitride (Si3N4), calcium fluoride (CaF2, wood chips, and the like. Note that, inFIG. 6(a) andFIG. 6(b), the reference numerals L1to L4shown in parenthesis in each of the resin layers44a,44bindicate the hardness of the first layer to the fourth layer, respectively. Further, the hardness of the second layer and that of the third layer are each hardness of portions of the layer other than the anti-swelling agent.

FIG. 7shows an exemplary blending ratio (%) of two types of materials, i.e., a hard material and a soft material, blended in each of the resin layers44a,44b. More specifically, the hard material may be PAI (polyimide amide), FEP (tetrafluoro ethylene.hexafluoropropylene copolymer), or a combination of these materials. Further, the soft material may be PTFE (poly tetrafluoro ethylene), graphite, MoS2(molybdenum disulfide), or a combination of these materials.

As shown inFIG. 7, the blending ratio of the hard material and the soft material varies in four stages from the layer closest to the base43. The number of stages is the same as the number of the layers. Namely, the blending ratio of the hard material is 75% in the first layer, 55% in the second layer, 35% in the third layer, and 15% in the fourth layer. As such, the more distant the layer is from the base43, the less the blending ratio of the hard material becomes. On the other hand, the blending ratio of the soft material is 25% in the first layer, 45% in the second layer, 65% in the third layer, and 85% in the fourth layer. As such, the more distant the layer is from the base43, the more the blending ratio of the soft material becomes. In other words, the hardnesses L1to L4of the resin layers44a,44bare such that, the more distant the layer is from the base43, the less the hardness becomes. Further, the difference in the hardness between adjacent two layers out of the resin layers44a,44bis as follows. Namely, the hardness differential ΔL12(=L1−L2) between the first layer and the second layer, the hardness differential ΔL23(=L2−L3) between the second layer and the third layer, the hardness differential ΔL34(=L3−L4) between the third layer and the fourth layer are all smaller than the hardness differential ΔL14(=L1−L4) between hardness L4of the fourth layer most distant from the base43and the hardness L1of the first layer closest to the base43. The adhesive strength between two adjacent layers increases with a decrease in the hardness differential. Therefore, in the present embodiment, the adhesive strength between the first layer and the second layer, the adhesive strength between the second layer and the third layer, and the adhesive strength between the third layer and the fourth layer are all greater than the adhesive strength between the first layer and the fourth layer in cases of forming the fourth layer on the surface of the first layer.

Further, the hardness of the fourth layer most distant from the base43is smaller than that of the metal material constituting the front head20and the rear head50. Note that, in the present embodiment, the hardnesses of the rest of three layers are also smaller than that of the metal material constituting the front head20and the rear head50. Further, the bend elastic constant of each layer constituting the resin layers44a,44bis smaller than the Young's modulus of the metal material constituting the base43, the front head20, and the rear head50. Note that the “two members provided so as to sandwich the resin layer” are base43and the front head20in cases of the resin layer44aprovided on the top surface of the piston40, and are base43and the rear head50in cases of the resin layer44bprovided on the under surface of the piston40.

Next, the following describes an operation of the compressor1of the present embodiment, with reference toFIG. 2(a) toFIG. 2(d).FIG. 2(a) shows a state where the piston40is at the upper dead center, andFIG. 2(b) toFIG. 2(d) show states where the shaft8has rotated by 90°, 180° (lower dead center), and 270° from the state ofFIG. 2(a), respectively.

Driving the motor7to rotate the shaft8, while the refrigerant is supplied from the inlet pipe fitting3to the compression chamber31through the draw-in hole32, causes the roller41mounted to the eccentric portion8ato move along the circumferential wall of the compression chamber31, as shown inFIG. 2(a) toFIG. 2(d). This way, the refrigerant is compressed in the compression chamber31. The following details how the refrigerant is compressed.

When the eccentric portion8arotates from, the state shown inFIG. 2(a) in the direction of the arrow in the figure, the space formed between the outer circumference surface of the roller41and the circumferential wall of the compression chamber31is divided into the low pressure chamber31aand the high pressure chamber31b, as shown inFIG. 2(b). When the eccentric portion8afurther rotates, the volume of the low pressure chamber31aincreases as shown inFIG. 2(b) toFIG. 2(d), and therefore, the refrigerant is drawn from the inlet pipe fitting3to the low pressure chamber31athrough the draw-in hole32. At the same time, the volume of the high pressure chamber31bdecreases, and this compresses the refrigerant in the high pressure chamber31b.

When the pressure inside the high pressure chamber31bis a predetermined pressure, the valve structure provided to the front head20is opened and the refrigerant in the high pressure chamber31bis ejected to the muffler space M through the discharge hole22. After that, the eccentric portion8areturns to the state shown inFIG. 2(a), and ejection of the refrigerant from the high pressure chamber31bis completed. Repeating this process enables successive compression and ejection of the refrigerant supplied from the inlet pipe fitting3to the compression chamber31.

The refrigerant, ejected to the muffler space M is ejected outside the compressing structure10from the muffler discharge hole (not shown) of the muffler11. The refrigerant ejected from the compressing structure10passes through an air gap between the stator7band the rotor7a, or the like, and then finally discharged outside the closed casing2from the outlet pipe fitting4.

At this time the lubricating oil L supplied to the compression chamber31from the outlet hole8cof the shaft8is partially ejected to from the discharge hole22to the muffler space M along with the refrigerant, and then, ejected from the muffler discharge hole (not shown) of the muffler11to the outside the compressing structure10. The lubricating oil L ejected to the outside the compressing structure10is partially returned to the storage at the bottom of the closed casing2through the oil-returning hole23of the front, head20. Further, another part of the lubricating oil L ejected to the outside the compressing structure10passes the air gap between the stator7band the rotor7aalong with the refrigerant, and then returns to the storage at the bottom, of the closed, casing2, through the gap between the recess (not shown) formed on the outer circumference surface of the stator7band the inner circumference surface of the closed casing2, and the oil-returning hole23of the front head20.

As described, the vertical length of the piston40is slightly smaller than the vertical length of the compression chamber31. Therefore, during the ordinary operation of the compressor1, the lubricating oil L ejected from the outlet hole8cof the shaft8exists in the minute gap D1between the upper end surface of the piston40and the front head20, and in the minute gap D2between the lower end surface of the piston40and the rear head50(hereinafter, these gaps are referred to as axial directional gaps D1, D2), as shown inFIG. 5(a).

Further, as hereinabove described, the external diameter of the roller41is such that, while the roller41is mounted to the eccentric portion8a, there is a minute radial-directional gap d1between the circumferential wall of the compression chamber31and the outer circumference surface of the roller41. Therefore, during the ordinary operation of the compressor1, the lubricating oil L discharged from the outlet hole8cof the shaft8is in the radial-directional gap d1, as shown inFIG. 5(a).

[Characteristics of Compressor of First Embodiment]

In the compressor1of the present embodiment, the fourth layer most distant from the base43in the resin layers44a,44bis soft. In cases of high-speed activation of the compressor1or in cases where the compressor is operated under conditions such that the temperature of the refrigerant ejected significantly differs from the temperature of the incoming refrigerant, the amount of thermal expansion of the piston40may be greater than that of the cylinder30. This may lead to a problem that the resin layers44a,44bswell by absorbing the refrigerant or the lubricating oil L, thus causing the fourth layer most distant from the base43to slide in contact with the front head20or the rear head50as shown inFIG. 5(b). However, even in such a case, the fourth layer most distant from, the base43is easily worn out or, if not, easily deformed. This reduces the surface pressure between the contact surfaces, thus reducing the frictional loss, and restrains deterioration in the efficiency of the compressor1.

By making the hardness L1of the first layer closest to the base43greater than the hardness L4of the fourth layer most distant from the base43, the hardness L1of the first layer closest to the base43is approximated, to the hardness of the base43. This improves the adhesive strength between the resin layers44a,44band the base43.

Further, in the compressor1of the present embodiment, the resin layers44a,44bare each made of four layers, and hardness differential between two adjacent layers (ΔL12, ΔL23, ΔL34) is kept smaller than the hardness differential ΔL14between the fourth layer most distant from the base43and the first layer closest to the base43. This reduces the frictional loss and prevents separation of the layers (first layer to fourth, layer) included in each of the resin layers44a,44b, while improving the adhesive strength between the resin layers44a,44band the base43.

Further, in the compressor1of the present embodiment, the resin layers44a,44bcontains an anti-swelling agent. This prevents the resin layers44a,44bfrom swelling by absorbing an oil or a refrigerant.

Further, of the first layer to the fourth layer in each of the resin layers44a,44b, the fourth layer most distant from the base43does not contain the anti-swelling agent. Therefore, when the surface of the resin layers44a,44bslides in contact with the front head20and the rear head50, the anti-swelling agent does not abuts the front head20and the rear head50. This reduces a frictional loss and restrains deterioration in the efficiency of the compressor1, as compared with cases where the fourth layer contains the anti-swelling agent.

Further, of the first layer to the fourth layer in each of the resin layers44a,44b, the first layer closest, to the base43does not contain the anti-swelling agent. Therefore, a decrease in the adhesive strength between the resin layers44a,44band the base43which is attributed to the anti-swelling agent does not take place. It is therefore possible to prevent separation of the resin layers44a,44bfrom the base43, as compared with cases where the first layer contains an anti-swelling agent.

Further, in the compressor1of the present embodiment, the thickness t2of the fourth layer which is softer than the first layer closest to the base43is kept not more than 50% of the thickness T1of each of the resin layers44a,44b. This reduces the amount of the resin layers44a,44bbeing worn out by dusts such as chips generated by wear-out, as compared with cases where the entire resin layers44a,44bis made as soft as the fourth layer is. Accordingly, damages to the entire resin layers44a,44bis kept small.

Further, in the compressor1of the present embodiment, the hardness of the fourth layer most distant, from the base43is smaller than the hardnesses of the front head20and the rear head50. Thus, when the resin layers44a,44bswell and slides in contact with the front head20or the rear head50, the fourth layer most distant from the base43is easily worn out.

Further, in the compressor1of the present embodiment, the bend elastic constant of the four layers constituting each of the resin layers44a,44bis small. Thus, when the resin layers44a,44bslides in contact with the front head20or the rear head50, due to swelling of the resin layers44a,44b, or the like, the resin layers44a,44bare easily elastically deformed.

Next, the following describes Second Embodiment, according to the present invention. A compressor of the present embodiment is different from the compressor of the First Embodiment in that the resin layer is provided not on the piston40, but on the front head or the rear head. Note that, elements of the present embodiment identical to those described in First Embodiment are given the same reference numerals and details for these elements are omitted.

As shown inFIG. 8andFIG. 9(a), a front head220of the present, embodiment has on its under surface a resin layer244in the form of thin film. Although illustration is omitted inFIG. 8, a rear head250also has on its top surface a resin layer245in the form of thin film (seeFIG. 9(a),FIG. 9(b)). As shown inFIG. 8, the resin layer244is formed in an area including an area where the top surface of the piston40slides (hatched area in the figure). Similarly, the resin layer245is formed in an area, including an area, where the under surface of the piston40slides.

As shown inFIG. 10(a),FIG. 10(b), each of the resin layers244,245is a stack of three layers, i.e., a first layer closest to the front head220or the rear head250, and a second layer and a third layer which are stacked in this order towards outside. That is, the third layer is most distant from the base of the front head220or the rear head250. The second layer is disposed between the first layer and the third layer, and connects the first layer with the third layer. Further, the thickness t21of each of the first layer and the second layer is the same, and the thickness t22of the third layer is smaller than the thickness t21of each of the first layer and the second layer. Thus, the thickness t22of the third layer is not more than 50% of the thickness T2(=2×t21+t22) of the resin layers244,245. Further, in the resin layers244,245, the second layer contains an anti-swelling agent which prevents swelling of the layer even when an oil of a refrigerant is absorbed, and the first layer closest to the base and the third layer most distant from the base do not contain the anti-swelling agent. Thus, the second layer is kept from swelling as compared with the first layer and the third layer. Note that, inFIG. 10(a) andFIG. 10(b), the reference numerals L21to L23shown in par entries is in each of the resin layers244,245indicate the hardness of the first layer to the third layer. Further, the hardness of the second layer is hardness of portions of the layer other than the anti-swelling agent.

As shown inFIG. 11, in the resin layers244,245, the blending ratio of the hard material and the soft material varies in three stages. The number of stages is the same as the number of the layers. Namely, the blending ratio of the hard material is 75% in the first layer, 55% in the second layer, and 35% in the third layer. As such, the more distant the layer is from the front head220or the rear head250, the less the blending ratio of the hard material becomes. On the other hand, the blending ratio of the soft material is 25% in the first layer, 45% in the second layer, and 65% in the third layer. As such, the more distant the layer is from the front head220or the rear head250, the more the blending ratio of the soft material becomes. In other words, the hardnesses L21to L23of the resin layers244,245are such that, the more distant the layer is from the front head220or the rear head250, the less the hardness becomes. Further, the difference in the hardness between adjacent two layers out of the resin layers244,245is as follows. Namely, the hardness differential ΔL12(=L21−L22) between the first layer and the second layer, the hardness differential ΔL23(=L22−L23) between the second layer and the third layer, are all smaller than the hardness differential ΔL13(=L21−L23) between hardness L23of the third layer most distant from the base and the hardness L21of the first layer closest to the base. In the present embodiment, the adhesive strength between the first layer and the second layer, and the adhesive strength between the second layer and the third layer are all greater than the adhesive strength between the first layer and the third layer in cases of forming the third layer on the surface of the first layer.

Further, the hardness of the third layer most distant from the base is smaller than that of the metal material constituting the piston40. In the present embodiment, the hardness of each of the rest of two layers is also smaller than the hardness of the metal material constituting the piston40. Further, the bend elastic constant of each layer constituting the resin layers244,245is smaller than the Young's modulus of the metal material constituting the base of the front head20, the base of the rear head50, and the piston40. Note that the “two members provided so as to sandwich the resin layer” are the base of the front head20and the piston40in cases of the resin layer244provided to the under surface of the front head20, and are base of the rear head50and the piston40in cases of the resin layer245provided to the top surface of the rear head50.

[Characteristics of Compressor of Second Embodiment]

As in First Embodiment, in the compressor of the present embodiment, the frictional loss is reduced and each of the resin layers244,245is kept from separating from the base.

Next, the following describes Third Embodiment, according to the present invention. A compressor of the present embodiment is different from the compressor of the First Embodiment in that the resin layer344is provided on the outer circumference surface of the base43of the piston40(excluding the surface where the blade is attached), instead of providing the resin layers to the top surface or the under surface of the base43of the piston40. Note that elements of the present, embodiment identical to those of First Embodiment are given the same reference numerals and details of those elements are omitted.

As shown inFIG. 15, the resin layer344is a stack of four layers, i.e., a first layer closest to the outer circumference surface of the base43, and a second layer, third layer, and a fourth layer which are stacked in this order towards outside. That is, the fourth layer is most distant from the base43. Further, the thickness t31of each of the first layer to the third layer is the same, and the thickness t32of the fourth layer is smaller than, the thickness t31of each of the first layer to the third layer. Thus, the thickness t32of the fourth layer is not more than 50% of the thickness T3(=3×t31+t32) of the entire resin layer344. Further, as in the First Embodiment, in the resin layer344, the second layer and the third layer are each a layer containing an anti-swelling agent which prevents the layer from swelling even when an oil or a refrigerant is absorbed. The first layer and the fourth layer on the other hand, do not contain the anti-swelling agent. Therefore, the second layer and the third layer are kept from swelling as compared with the first layer and the fourth layer. Note that, inFIG. 15, the reference numerals L31to L34shown in parenthesis in each layer of the resin layer344indicate the hardness of the first layer to the fourth layer, respectively. Further, the hardness of the second layer and that of the third layer are each hardness of portions of the layer other than the anti-swelling agent.

As in the resin layers44a,44bof First Embodiment, in the resin layer344, the blending ratio (%) of the hard material and the soft material is varied, in four stages. The number of stages corresponds to the number of layers. In the resin, layer344, the hardness differential of two adjacent layers is as follows. Namely, the hardness differential (=L31−L32) between the first layer and the second layer, the hardness differential (=L32−L33) between the second, layer and the third layer, the hardness differential (=L33−L34) between the third layer and the fourth layer are all smaller than the hardness differential (=L31−L34) between the hardness L34of the fourth layer most distant from the base43and the hardness L31of the first layer closest to the base43. In the present embodiment, the adhesive strength between the first layer and the second layer, the adhesive strength between the second layer and the third layer, and the adhesive strength between the third layer and the fourth layer are all greater than the adhesive strength between the first layer and the fourth layer in cases of forming the fourth layer on the surface of the first layer.

Further, the hardness of the fourth layer most distant from the base43is smaller than the hardness of the metal material constituting the cylinder30. In the present embodiment, the hardness of each of the rest of three layers is also smaller than the hardness of the metal material constituting the cylinder30. Further, the bend elastic constant of each layer constituting the resin layer344is smaller than the Young's modulus of the metal material constituting the base43and the cylinder30. Note that the “two members provided so as to sandwich the resin layer” are the base43and the cylinder30.

[Characteristics of Compressor of Third Embodiment]

As in First Embodiment, in the compressor of the present embodiment, the frictional loss is reduced while the resin layer344is kept from separating from the base43.

Next, the following describes Fourth Embodiment, according to the present invention. A compressor of the present embodiment is different, from, the compressor of First Embodiment in that a resin layer444is provided to the inner circumference surface of the cylinder30(excluding the refrigerant inlet hole, and opening of the blade storage groove), instead of providing a resin layer to the piston40. Note that elements of the present embodiment identical to those of First Embodiment are given the same reference numerals and details of those elements are omitted.

The resin layer444is a stack of three layers, i.e., a first layer closest to the inner circumference surface of the base of the cylinder30, and a second layer and a third layer which are stacked in this order towards outside. In other words, the third layer is most distant from, the base of the cylinder30. The second layer is disposed between the first layer and the third layer, and connects the first layer with the third layer. The thickness of the first layer and that of the second layer is the same, and the thickness of the third layer is smaller than those of the first layer and the second layer. The thickness of the third layer is not more than 50% of the thickness of the resin, layer444. Further, as in First Embodiment, in resin layer444, the second layer contains an anti-swelling agent which keeps the layer from absorbing an oil and a refrigerant, and the first layer and the third layer do not contain the anti-swelling agent. Therefore, the second layer is kept from swelling as compared with the first layer and the third layer.

As in the case of the resin layers244,245of Second Embodiment, in the resin layer444, the blending ratio (%) of the hard, material and the soft material is varied in three stages. The number of stages corresponds to the number of layers. In the resin layer444, the hardness differential between two adjacent layers is as follows. Namely, the hardness differential between the first layer and the second layer, the hardness differential between the second layer and the third layer are all smaller than the hardness differential between the hardness of the third layer most distant from the base and the first layer closest to the base. In the present embodiment, the adhesive strength between the first layer and the second layer, and the adhesive strength between the second layer and the third layer are both stronger than the adhesive strength between the first layer and the third layer in cases of forming the third layer to the surface of the first layer.

Further, the hardness of the third layer most distant from the base is smaller than the hardness of the metal material constituting the piston40. Note that, in the present embodiment, the hardness of each of the rest of two layers is also smaller than the hardness of the metal material constituting the piston40. Further, the bend elastic constant of each layer constituting the resin layer444is smaller than the Young's modulus of the metal material constituting the base of the cylinder30and the piston40. Note that the “two members provided so as to sandwich the resin layer” are the base of the cylinder30and the piston40.

[Characteristics of Compressor of Fourth Embodiment]

As in First Embodiment, in a compressor of the present, embodiment, the frictional loss is reduced while the resin layer444is kept from separating from the base.

The following describes Fifth Embodiment, according to the present invention. The present embodiment is an exemplary application of the present invention to a dual-cylinder rotary compressor. As shown inFIG. 17, a compressor501of the present embodiment is different from First. Embodiment in the structures of the shaft508and the compressing structure510. Further, the compressor501of the present embodiment has two inlet pipe fittings3on a side of the closed casing2, aligned in the vertical direction. The structure other than the above is the same as that of First Embodiment. Therefore, the same reference numerals are given and the explanations are omitted as needed.

The shaft508has two eccentric portions508a,508d. The shaft centers of the two eccentric portions508a,508aare shifted from, each other by 180° about the rotational axis of the shaft508. Further, as in the shaft8of First Embodiment, the shaft508has a lubrication path508band a plurality of outlet holes508c.

The compressing structure510sequentially has, from, the top to the bottom along the axial direction of the shaft508, a front muffler511, a front head520, a cylinder530, a piston540, a middle plate550, a cylinder560, piston570, a rear head580, and a rear muffler512. The front head520and the middle plate550are disposed at the upper and lower ends of the piston540, and correspond to the first end plate member and the second end plate member of the present invention, respectively. Further, the middle plate550and the rear head580are disposed at the upper and lower ends of the piston570, and correspond to the first end plate member and the second end plate member of the present invention, respectively.

The front muffler511has a structure similar to that of the muffler11of First Embodiment, and forms a muffler space M1between the muffler511and the front head520.

To the front head520are formed a bearing hole521, a discharge hole522(seeFIG. 18), and an oil-returning hole523. Further, the front head520has a through hole (not shown) penetrating the front head520in the vertical direction. The through hole constitute a part of the passage for discharging a refrigerant in the muffler space M2formed by the rear head580and the rear muffler512to the muffler space M1. The structure of the front head520other than this through hole is the same as that of the front head20of First Embodiment.

As shown inFIG. 18, in the cylinder530are formed a compression chamber531, a draw-in hole532, and a blade housing533. Further, the cylinder530has a through hole535formed at its outer circumference-side portion of the compression chamber531. The through hole535is for discharging the refrigerant in the later-mentioned muffler space M2to the muffler space M1. The structure of the cylinder530other than this through hole535is the same as that of the cylinder30of First Embodiment.

The structure of the piston540is similar to that of the piston40of First Embodiment, and includes a roller41and a blade42. The roller41is rotatably mounted to the outer circumference surface of the eccentric portion508a. The blade42is disposed between a pair of bushes34in the blade housing533of the cylinder530and is capable of moving forward and backward.

The middle plate550is an annular plate member which is disposed between the cylinder530and the cylinder560, and closes the lower end of the compression chamber531of the cylinder530while closing the upper end of the compression chamber531of the cylinder560. Further, the middle plate550has a through hole (not shown) for discharging the refrigerant in the later-mentioned muffler space M2to the muffler space M1. The middle plate550is made of a metal material and example manufacturing methods include sintering of metal powder, casting, cutting, or the like.

The structure of the cylinder560is similar to that of the cylinder530, and includes a compression chamber561, a draw-in hole562, a blade housing (not shown) in which the pair of bushes34are disposed, and a through hole (not shown).

The structure of the piston570is similar to that of the piston40of First Embodiment and includes the roller41and the blade42. The roller41is rotatably mounted to the outer circumference surface of the eccentric portion508d. The blade42is disposed between a pair of bushes34in the blade housing (not shown) of the cylinder560and is capable of moving forward and backward.

The rear head580is disposed on the lower side of the cylinder560and closes the lower end of the compression chamber531of the cylinder560. The rear head580is a substantially annular member, and its center portion has a bearing hole581into which the shaft508is rotatably inserted. Further, to the rear head580is formed a discharge hole (not shown) for discharging the refrigerant compressed in the compression chamber561of the cylinder560to the muffler space M2formed between the rear head580and the rear muffler512. Further, to the rear head580is formed a through hole (not shown) for discharging the refrigerant in the muffler space M2to the muffler space M1. On the under surface of the rear head580is provided a valve structure (not shown) which opens and closes the discharge hole according to the pressure in the compression chamber531. The rear head580is made of a metal material and example manufacturing methods include sintering of metal powder, casting, cutting, or the like.

The rear muffler512is provided for reducing the noise generated when the refrigerant is ejected from the discharge hole (not shown) from the rear head580. The rear muffler512is attached to the under surface of the rear head580by using a bolt and forms the muffler space M2between the rear muffler512and the rear head580. The muffler space M2is in communication with the muffler space M1through the through holes of the rear head580, the cylinder560, the middle plate550, the cylinder530, and the front head520.

In the compressor of the present embodiment, resin layers44a,44b(seeFIG. 4) similar to those of First Embodiment may be formed in a whole area or in a part of the upper end surface and the lower end surface of the piston540,570. Further, resin layers244,245(seeFIG. 8,FIG. 9) similar to those in Second Embodiment may be formed in a whole area or in a part of the lower end surface of the front head520, the upper and lower end surfaces of the middle plate550, and the upper end surface of the rear head580. Further, a resin layer344(seeFIG. 12toFIG. 14) similar to that in Third Embodiment may be formed in a whole area or in a part of the outer circumference surface of the roller41of the pistons540,570. Further, a resin layer444(seeFIG. 16) similar to that in. Fourth Embodiment may be formed in a whole area or in a part of the inner circumference surface of the cylinders530,560.

The following describes an operation of the compressor501of the present embodiment. When the motor7is driven to rotate the shaft508, while supplying the refrigerant from the draw-in holes532,562to the compression chambers531,561, the roller41of the piston540mounted to the eccentric portion508amoves along the circumferential wall of the compression chamber531. This compresses the refrigerant in the compression chamber531. Meanwhile, the roller41on the piston570mounted to the eccentric portion508dmoves along the circumferential wall of the compression chamber561. This compresses the refrigerant in the compression chamber561.

When the pressure inside the compression chamber531reaches a predetermined pressure or higher, the valve structure provided to the front head520opens and the refrigerant in the compression chamber531is ejected to the muffler space M1from the discharge hole22on the front head520. Further, when the pressure inside the compression chamber561reaches a predetermined pressure or higher, the valve structure provided to the rear head580opens and the refrigerant in the compression chamber561is ejected to the muffler space M2from the discharge hole (not shown) on the rear head580. The refrigerant ejected to the muffler space M2is then ejected to the muffler space M1through the through holes of the rear head580, the cylinder560, the middle plate550, the cylinder530, and the front head520.

The refrigerant ejected, to the muffler space M1is ejected, outside the compressing structure510from the muffler discharge hole (not shown) of the front muffler511, passes the air gap between the stator7band the rotor7a, and then discharged from the outlet pipe fitting4to outside the closed casing2.

[Characteristics of Compressor of Fifth Embodiment]

As in First Embodiment, in the compressor of the present embodiment, the frictional loss is reduced while the resin layer is kept from separating from the base.

Next, the following describes a. Sixth Embodiment of the present invention. A compressor of the present embodiment is different from First Embodiment in the structure of its compressing structure610. The structure other than the above is the same as that of First Embodiment. Therefore, the same reference numerals are given and the explanations are omitted as needed.

As shown inFIG. 19, the compressing structure610is different from the cylinder630in its structure of the members arranged inside the cylinder630; however, the structures other than that are the same as those of First Embodiment.

The cylinder630has a compression chamber631and a draw-in hole632. Further, the cylinder630has a vane housing633in place of the blade housing33of First Embodiment, and the structures other than that are the same as those of the cylinder30of First Embodiment. The vane housing633penetrates the cylinder630in the vertical direction, and is in communication with the compression chamber631. Further, the vane housing633extends in a radial direction of the compression chamber631.

Inside the compression chamber631is an annular roller641. The roller641is disposed inside the compression chamber631and is mounted to the outer circumference surface of the eccentric portion8aso that relative rotation is possible. The vertical length of the roller641is the same as the vertical length H1of the piston40of First Embodiment. Further, the external diameter of the roller641is the same as that of the roller41of the piston40of First Embodiment.

Inside the vane housing633is disposed a vane644. As shown inFIG. 20, the vane644is a flat plate member and its vertical length is the same as the vertical length of the roller641.

The leading end portion of the vane644, which is an end on the side closer to the center of the compression chamber631(the leading end portion on the lower side inFIG. 19), has a tapered shape when viewed, from the top. Further, the vane644is biased by a biasing spring647provided inside the vane housing633, and the leading end portion on the side of the compression chamber631is pressed against the outer circumference surface of the roller641. Therefore, as shown inFIG. 19(a) toFIG. 19(d), when the roller641moves along the circumferential wall of the compression chamber631with rotation of the shaft8, the vane644moves forward and backward in a radial direction of the compression chamber631within the vane housing633. Further, as shown inFIG. 19(b) toFIG. 19(d), when the vane644sticks out from the vane housing633towards the compression chamber631, the space formed between the outer circumference surface of the roller641and the circumferential wall of the compression chamber631is divided into a low pressure chamber631aand the high pressure chamber631bby the vane644.

As shown inFIG. 20andFIG. 21, the roller641includes a base642made of a metal material, and resin layers643ato643cwhich are thin films coating the surfaces of the base642. Further, the vane644includes a base645made of a metal material, and resin layers646a,646bwhich are thin films coating the surfaces of the base645.

As shown inFIG. 20, the bases642,645have a shape similar to the shapes of the roller641and the vane644. The bases642,645are made by sintering metal powder, casting, or cutting, and their surfaces are polished.

The resin layers643a,643bof the roller641coats the top surface and the under surface of the base642, respectively. In other words, the resin layers643a,643bare formed on the upper and lower end surfaces of the roller641, respectively. Further, the resin layer643cis formed on the outer circumference surface of the roller641. Further, the resin layers646a,646bof the vane644are formed on the top surface and the under surface of the base645, respectively. In other words, the resin layers646a,646bare formed on the upper and lower end surfaces of the vane644. The material and the film thickness of the resin layers643ato643c,646,646bare the same as those of the resin layers44a,44bon the piston40of First Embodiment.

Next, the following describes an operation of the compressor of the present embodiment. TheFIG. 19(a) shows that the roller641is at the upper dead center, andFIG. 19(b) toFIG. 19(d) shows states where the shaft8rotates by 90°, 180° (lower dead center), and 270° from the state ofFIG. 19(a), respectively.

when the motor7is driven to rotate the shaft8, while the refrigerant is supplied from the inlet pipe fitting3to the compression chamber631through the draw-in hole632, the roller641mounted to the eccentric portion8amoves along the circumferential wall of the compression chamber631, as shown inFIG. 19(a) toFIG. 19(d). This compresses the refrigerant in the compression chamber631. The following details the process in which the refrigerant is compressed.

When the eccentric portion8arotates in the direction shown by the arrow in the figure from the state shown inFIG. 19(a), the space formed between the outer circumference surface of the roller641and the circumferential wall of the compression chamber631is divided into a low pressure chamber631aand a high pressure chamber631b, as shown inFIG. 19(b). When the eccentric portion8afurther rotates, the volume of the low pressure chamber631aincreases as shown inFIG. 19(b) toFIG. 19(d). Therefore, the refrigerant is drawn into the low pressure chamber631afrom the inlet pipe fitting3through the draw-in hole632. At the same time, the volume of the high pressure chamber631bis reduced. Therefore, the refrigerant in the high pressure chamber631bis compressed.

Then, when the pressure inside the high pressure chamber631breaches a predetermined pressure or higher, the valve structure provided to the front head20is opened and the refrigerant in the high pressure chamber631bis ejected to the muffler space M from the discharge hole22. The refrigerant ejected to the muffler space M flows the path similar to the compressor1of First Embodiment, and at the end, is discharged from the outlet pipe fitting4to the outside the closed casing2.

[Characteristics of Compressor of Sixth Embodiment]

As in First Embodiment, in the compressor of the present embodiment, the frictional loss is reduced while the resin layer is kept from separating from the base.

Next, the following describes a Seventh embodiment of the present invention. The present embodiment is an exemplary application of the present invention to a scroll compressor. As shown inFIG. 22, a compressor701of the present embodiment includes a closed casing702, a compressing structure710disposed inside the closed casing702, and the drive mechanism706.FIG. 22omits hatching that indicates the cross section of the drive mechanism706. The following description of the compressor701assumes that the up/down direction of theFIG. 22is the vertical direction.

The closed casing702is a cylindrical container with its both ends closed. On top of the closed casing702is provided an inlet pipe fitting703for introducing the refrigerant. On a side of the closed casing702is provided an outlet pipe fitting704for discharging the compressed refrigerant, and a terminal (not shown) for supplying electricity to the coil of a later-mentioned stator707bin the drive mechanism706. Further, at the bottom in the closed casing702is stored a lubricating oil L for smoothening the operation of the slide portion in the compressing structure710. Inside the closed casing702, the compressing structure710and the drive mechanism706are disposed, aligned in the vertical direction.

The drive mechanism706includes a motor707serving as a drive source, and a shaft708attached to this motor707. In other words, it includes the motor707and the shaft708for transmitting the drive force of the motor707to the compressing structure710.

The structure of the motor707is substantially the same as that of the motor7of First Embodiment, and includes a substantially annular stator707bwhich is fixed to the inner circumference surface of the closed casing702, and a rotor707adisposed on the radially inner side of the stator707bwith an air gap therebetween. Further, the outer circumference surface of the stator707bis not entirely in close contact with the inner circumference surface of the closed casing702, i.e., a plurality of recesses (not shown) extending in the vertical direction and communicating the spaces above and below the motor707are provided along the outer circumference surface of the stator707b.

The shaft708is for transmitting the drive force of the motor707to the compressing structure710, and is fixed to the inner circumference surface of the rotor707ato rotate integrally with the rotor707a. The shaft708has at its upper end portion an eccentric portion708a. This eccentric portion708ahas a cylindrical shape and its shaft center is deviated from, the rotational center of the shaft708. To this eccentric portion708ais mounted a later-mentioned bearing portion743of the moveable scroll740.

Further, in the shaft708is formed a lubrication path708bwhich penetrates the shaft708in the vertical direction. At the lower end portion of this lubrication path708bis a pump member (not shown) for drawing in the lubricating oil L into the lubrication path708bwith rotation of the shaft708.

Further, the shaft708has a plurality of outlet holes708cfor discharging the lubricating oil L in the lubrication path708bto the outside the shaft708.

The compressing structure710includes a housing720fixed to the inner circumference surface of the closed casing702, a fixed scroll (first scroll)730disposed on top of the housing720, a moveable scroll (second scroll)740disposed between the housing720and the fixed, scroll730.

The housing720is a substantially annular member, and is press fit and fixed to the closed, casing702. The entire outer circumference surface of the housing720is closely attached to the inner circumference surface of the closed casing702. At the center portion of the housing720are formed an eccentric portion storage hole721and a bearing hole722whose diameter is smaller than the eccentric portion storage hole721. The eccentric portion storage hole721and the bearing hole722are aligned in the vertical direction. Inside the eccentric portion storage hole721, the eccentric portion708aof the shaft708is stored while being inserted inside the bearing portion743of the moveable scroll740. The bearing hole722supports the shaft708so as to enable relative rotation of the shaft708through the bearing723. Further, an annular groove724is formed on the top surface of the housing720, on the outer circumference-side of the eccentric portion storage hole721. Further, on the outer circumference of the annular groove724is a communication hole725penetrating the housing720in the vertical direction.

As shown inFIG. 22andFIG. 23, the fixed scroll730is a substantially disc-like member, whose outer circumference-side portion of the under surface is fixed to the housing720by using a bolt (not shown) so as to closely contact the top surface of the housing720. At the center portion on the under surface of the fixed scroll730is formed a substantially circular recess731. Further, on the bottom surface (ceiling surface) of the recess731is formed a fixed-side wrap (first wrap)732having a spiral shape, which project downwards. The under surface (excluding the bottom surface of the recess731) of the fixed scroll730and the leading end surface of the fixed-side wrap732are substantially flush with each other. Further, as shown inFIG. 23, the end portion (winding-end end portion) of the fixed-side wrap732, on the outer circumference-side is connected to the circumferential wall of the recess731.

Further, as shown inFIG. 22, the fixed scroll730has a draw-in path733extended from the top surface to the vicinity of the under surface of the fixed scroll730. The draw-in path733is for introducing a refrigerant into the recess731. At the upper end of the draw-in path733is inserted an inlet pipe fitting703. As shown inFIG. 23, the lower end of this draw-in path733is formed on the bottom surface of the recess731, where the radius of the recess731is the largest.

At substantially the center portion of the top surface of the fixed scroll730, a recess734is formed, and a cover member735is attached to the fixed scroll730so as to cover the recess734. Further, at the bottom surface of the recess734is formed a discharge hole736extended downward and in communication with the recess731. The lower end of the discharge hole736is formed at substantially the center portion of the bottom surface of the recess731. Further, on the fixed scroll730is formed a communication hole737which communicates a space surrounded by the recess734and the cover member735with the communication hole725formed on the housing720. Note thatFIG. 23omits illustration of the bolt hole formed on the fixed scroll730, and a later-mentioned communication hole737. Further, the fixed scroll730is made of a metal material, and example manufacturing methods include sintering metal powder, casting, cutting, or the like.

The moveable scroll740includes a disc-like flat plate section741, a spiral moveable-side wrap742projecting upward from the top surface of the flat plate section741, and a cylindrical bearing portion743which projects downwards from the under surface of the fiat plate section741. Inside the bearing portion743is inserted the eccentric portion708aso that relative rotation is possible.

The flat plate section741is sandwiched by the under surface of the fixed scroll730and the upper end of the peripheral wall section of the eccentric portion storage hole721. Further, the flat plate section741is supported by the housing720through the Oldham ring750disposed in the annular groove724. The Oldham ring750is for preventing the rotation movement of the moveable scroll740, and has sub-protrusions (not shown) on its top and under surfaces. The sub-protrusions engage with linear grooves (not shown) formed on the housing720and the moveable scroll740and which extend in a direction perpendicular to each other. This way the Oldham ring750is able to move relatively to the housing720and the moveable scroll740(i.e., two directions perpendicular to each other). Therefore, the moveable scroll740is moveable in horizontal directions with respect to the housing720, while keeping its orientation (angle) constant. With the flat plate section741supported by the housing720through the Oldham ring750and with the eccentric portion708ainserted into the bearing portion743so that relative rotation is possible, rotation of eccentric portion708a(shaft708) causes the moveable scroll740to move (circle) about the rotational axis of the shaft708, without rotating about the center of the moveable scroll740.

Further, the flat plate section741has a small hole (not shown) which guides the compressed refrigerant in the recess731to the eccentric portion storage hole721of the housing720. Thus, during the operation of the compressor701, the flat plate section741receives an upward force from the high-pressure refrigerant in the eccentric portion storage hole721, and the top surface of the flat plate section741is pressed against the under surface of the fixed scroll730. This prevents the high-pressure refrigerant in the recess731from pressing the moveable scroll740downward, increasing later-mentioned axial directional gaps D3, D4.

Further, as shown inFIG. 23, the moveable-side wrap742of the moveable scroll740is substantially symmetrical to the fixed-side wrap732of the fixed scroll730, and is disposed on the flat plate section741so as to engage with the fixed-side wrap732. Thus, a plurality of substantially crescent spaces are formed between the side surface of the fixed-side wrap732and the circumferential wall of the recess731and the side surface of the moveable-side wrap742.

FIG. 24(b) show the compressor701at the time of shipment. As shown inFIG. 24(b), the moveable-side wrap742is formed so as to move along the side surface of the fixed-side wrap732when the moveable scroll740circles, while the side surface of the moveable-side wrap742approximates to the side surface of the fixed-side wrap732and the circumferential wall of the recess731with a minute gap d2(hereinafter, the gap is referred to as radial-directional gap d2) of, for example, 10 to 30 μm therebetween. Further, as shown inFIG. 24(a), between the top surface of the flat plate section741of the moveable scroll740and the leading end surface of the fixed-side wrap732, and between the bottom surface of the recess731of the fixed scroll730and the leading end surface of the moveable-side wrap742, there are minute gaps D3, D4(hereinafter, these gaps are referred to as axial directional gaps D3, D4) of, for example, approximately 10 to 30 μm, respectively.

As shown inFIG. 24, the moveable scroll740of the present embodiment includes: a base745made of a metal material and resin layers746ato746dwhich are thin films covering the surfaces of the base745. The shape of the base745is substantially the shape of the moveable scroll740. The base745is formed by sintering of metal powder, casting, or cutting.

As shown inFIG. 24(a), the resin layer746ais formed on a leading end surface of the moveable-side wrap742. Further, the resin layer746bis formed in an area of the top surface of the flat plate section741, which opposes the bottom surface of the recess731(an area of the fixed-side wrap732opposing the leading end surface). Further, as shown inFIG. 24(a) andFIG. 24(b), the resin layers746c,746dare formed on the outer circumference surface and the inner circumference surface of the moveable-side wrap742. The material of the resin layers746ato746dand the film thickness of the same at the time of shipment are the same as the resin layers44a,44con the piston40of First Embodiment. Note that, as in First Embodiment, the resin layers746ato746dat the time of shipment are hardly swollen.

Next, the following describes an operation of the compressor701of the present embodiment, with reference toFIG. 23(a) toFIG. 23(d),FIG. 23(b) toFIG. 23(d) show the states where the shaft708has rotated by 90°, 180°, and 270° from the state shown inFIG. 23(a).

When the motor707is driven to rotate the shaft708, while the refrigerant is supplied from the inlet pipe fitting703to the recess731through the draw-in path733, the moveable scroll740mounted to the eccentric portion708acircles without rotating, as shown inFIG. 23(a) toFIG. 23(d). With this, the substantially crescent spaces formed by the side surfaces of the moveable-side wrap742, the fixed-side wrap732, and the circumferential wall of the recess731move towards the center, while reducing their volumes. This way the refrigerant is compressed in the recess731.

In the following description, with reference toFIG. 23(a), on the process of compressing the refrigerant, the substantially crescent spaces (spaces indicated by dot hatching in the figure) at the outermost circumference is focused. In the state shown inFIG. 23(a), the refrigerant is supplied from the draw-in path733into the substantially crescent space. When the shaft708rotates from this state, the volume of the space increases as shown inFIG. 23(b), and the refrigerant is drawn in from the draw-in path733. When the shaft708further rotates from this state, the crescent space moves towards the center as shown inFIG. 23(c) andFIG. 23(d), and the space is no longer in communication with the draw-in path733and its volume decreases. Therefore, in this space, the refrigerant is compressed. With the rotation of the shaft708, the space further moves towards the center and shrinks. When the shaft708rotates twice, the space moves to the position indicated by grid hatching inFIG. 23(a). When the shaft708further rotates, the space matches with a space surrounded by the inner circumference surface of the moveable-side wrap742and the outer circumference surface of the fixed-side wrap732, and is in communication with the discharge hole736as indicated by the grid hatching inFIG. 23(c). This way, the compressed refrigerant in the space is ejected from, the discharge hole736.

The refrigerant ejected from the discharge hole736passes the communication hole737of the fixed scroll730and the communication hole725of the housing720and then discharged into the space below the housing720. Then, the refrigerant is finally ejected to the outside the closed casing702from the outlet pipe fitting704.

As hereinabove mentioned, the axial directional gaps D3, D4are formed between the leading end surface of the fixed-side wrap732and the top surface of the flat plate section741of the moveable scroll740and between the leading end surface of the moveable-side wrap742and the bottom, surface of the recess731of the fixed, scroll730, respectively (seeFIG. 24). Therefore, during an ordinary operation of the compressor701, there is the lubricating oil L discharged from the outlet hole708cof the shaft708in the axial directional gaps D3, D4(illustration omitted).

Further, as hereinabove described, the radial-directional gap d2is formed in a plurality of parts between the side surface of the move able-side wrap742, the side surface of the fixed-side wrap732, and the circumferential wall of the recess731(seeFIG. 24). Therefore, during an ordinary operation of the compressor701, there is the lubricating oil L discharged from the outlet hole708cof the shaft708in the radial-directional gap d2.

[Characteristic of Compressor of Seventh Embodiment]

As in First Embodiment, in the compressor of the present embodiment, the frictional loss is reduced while the resin layer is kept from separating from the base.

Thus, embodiments of the present invention are described hereinabove with reference to the drawings. However, the specific structure of the present invention shall not be interpreted as to be limited to the above described embodiments. The scope of the present invention is defined not by the above embodiments but by claims set forth below, and shall encompass the equivalents in the meaning of the claims and every modification within the scope of the claims.

The above described First to Seventh Embodiments deal with a case where the hardness of each layer in the resin layer is such that, the more distant the layer is from the base, the less the hardness becomes; however, the present, invention is not limited to those embodiments. As shown inFIG. 25, in a resin layer844which is a stack of five layers, i.e., a first layer to a fifth layer, the hardness LOS of the fifth layer most distant from the base43is smaller than the hardness L01of the first layer closest, to the base43, and the hardness differential (ΔL12, ΔL23, ΔL34, ΔL45) of two adjacent layers is smaller than the hardness differential (ΔL15) between the first layer and the fifth layer. Thus, for example, the hardness of each of the five layers, i.e., first layer to the fifth layer, may be such that, the more distant the layer is from the base, the less the hardness becomes.

The above described First to Seventh Embodiments deal with a case where the hardness of each of the layers constituting the resin layer is smaller than the hardness of the metal material of a member opposing to the resin layer; however, as long as the hardness of the layer most distant from the base is smaller than the hardness of the metal material, the hardnesses of the other layers may be greater than the hardness of the metal material.

The above described First to Seventh Embodiments deal with a case where a layer closest to the base and a layer most distant from, the base in the resin, layer do not contain an anti-swelling agent; however, the present, invention is not limited to those embodiments, as long as one of the layer closes to the base and the layer most distant from the base is a layer not containing the anti-swelling agent.

Therefore, the layer closest to the base may contain an anti-swelling agent, while the layer most distant from the base contains no anti-swelling agent. This reduces the frictional loss, and restrains deterioration in the efficiency of the compressor, even when the layer most distant from the base slides in contact with another member.

Further, the layer closest to the base may contain no anti-swelling agent, while the layer most distant from the base contains an anti-swelling agent. This prevents separation of the resin layer from the base.

Further, the above described First to Seventh Embodiments deal with a case where the layer between the layer closest to the base and the layer most distant from the base in the resin layer contain an anti-swelling agent; however, the present, invention is not limited to the embodiments, as long as any one of layers constituting the resin layer contains the anti-swelling agent.

The above described First to Seventh Embodiments deal with a case where the bend elastic constant of each of the layers constituting the resin layer is smaller than the Young's modulus of two members provided to sandwich the resin layer. However, as long as the bend elastic constant of at least one layer out of the layers constituting the resin layer is smaller than the Young's modulus of the two members, the bend elastic constant of each of the other layers may be greater than the Young's modulus of the two members.

The above described First Embodiment deals with a case where the resin layers44a,44bare formed in a whole area of the upper end surface and a whole area of the lower end surface of the base43, respectively; however, the present invention is not limited to the embodiment, and the resin layers44a,44bmay be formed in a part of the upper end surface and in a part of the lower end surface of the base43, respectively.

The above described Second Embodiment deals with a case where the resin layer244is formed in a part of the under surface of the front head220, which part including an area where the top surface of the piston40slides, and the resin layer245is formed in a part of the top surface of the rear head250, which part includes an area where the under surface of the piston40slides. However, the present invention is not limited to the embodiment. The resin layer244may be formed in a whole area of the under surface of the front head220, and the resin layer245may be formed in a whole area of the top surface of the rear head250.

The above described First to Seventh Embodiments deal with a case where the resin layer includes three or four layers; however, the present invention is not limited to the embodiments, and the number of layers in the resin layer may be five or more.

The above described First Embodiment deals with a case where the thickness of each of the first layer to the third layer in each of the resin layers44a,44bis the same; however, the present invention is not limited to the embodiment, and as long as the thickness t2of the fourth layer is not more than 50% of the thickness T1of each of the entire resin layers44a,44b, the thickness of each of the first layer to the third layer is not particularly limited.

The above described First Embodiment deals with a case where the thickness t2of the fourth layer is smaller than the thickness t1of each of the first layer to the third layer. However, the present invention is not limited to the embodiment, and the thickness t2of the fourth layer may be equal to or greater than the thickness t1of each of the first layer to the third layer, as long as the thickness t2of the fourth layer is not more than 50% of the thickness T1of each of the entire resin layers44a,44b.

The above described Sixth Embodiment deals with a case where the resin layer is formed in whole areas of the upper end surface, the lower end surface, and the outer circumference surface of the roller641, and in whole areas of the upper and lower end surfaces of the vane642. However, the present invention is not limited to the embodiment. Resin layers244,245(seeFIG. 8,FIG. 9) similar to those of Second Embodiment, according to the present invention may be formed in a whole area or in a part of the under surface of the front head and in a whole area or in a part of the top surface of the rear head. Further, a resin layer344(seeFIG. 12toFIG. 14) similar to that of Third Embodiment may be formed in a whole area or in a part of the outer circumference surface of the roller641. Further, a resin layer444(seeFIG. 16) similar to that of Fourth Embodiment may be formed in a whole area or in a part of the inner circumference of the cylinder630.

The above described Seventh Embodiment deals with a case where a resin layer is formed on the end surface of the moveable-side wrap (second wrap)742, an area of the top surface of the flat plate section741opposing to the bottom surface of the recess731(area opposing to the end surface of the fixed-side wrap (first wrap)732), and on the outer circumference surface and the inner circumference of the moveable-side wrap742. However, the present invention is not limited to the embodiment, and the similar resin layer may be formed in other parts (specifically, the end surface of the fixed-side wrap732, a part of the bottom surface of the recess731, opposing to the end surface of the moveable-side wrap742, a side surface of the fixed-side wrap732, and a circumferential wall of the recess731).

Industrial Applicability

The present invention realizes a compressor structured so as to restrain deterioration in the efficiency of the compressor, while preventing separation of a resin layer formed on an end surface of the piston or the like.