Patent Application
20130071279
The invention relates to a scroll-type fluid machine suitable for a refrigeration circuit used for vehicle air conditioning.
A scroll-type fluid machine of this type has fixed and movable scrolls each including an end plate and a spiral body integral with the end plate. The spiral bodies and the end plates come into sliding contact with each other between the fixed and movable scrolls, demarcating a compression or expansion chamber of working fluid, which is formed between the spiral bodies.
Patent Document 1 discloses a scroll-type compressor in which a base portion with a curvature radius (r) is provided to a corner located on the end plate side of a spiral body of one of the scrolls, and a rounded portion with a curvature radius (R) is provided to a corner located on the tip end of a spiral body of the other scroll, the curvature radius (R) being larger than the curvature radius (r).
Patent Document 2 discloses a scroll-type compressor in which a first chamfered portion in an arc-like shape is provided to the base portion of a spiral body, and a second chamfered portion in an arc-like shape, which is slightly smaller than the first chamfered portion, is provided to a corner of the tip end of the spiral body. The radii of first and second chamfered portions are 5 percent or less of thickness of the spiral body.
In a scroll-type compressor disclosed in Patent Document 3, a space for a compression chamber is formed in a surface of at least one of two scrolls, and is filled with a surface treatment material of less hardness than the other scroll.
Patent Document 4 discloses a scroll-type fluid machine in which an interference avoidance portion with respect to a base portion of a spiral body is formed in a second paneling (bottom plate).
Patent Document 5 discloses a scroll-type fluid machine in which a spiral body and an end plate come into sliding contact with each other between a fixed scroll and a movable scroll with a chip seal of the spiral body intervening therebetween, and the chip seal having a concave or convex cross-sectional shape is mounted on a tip end of the spiral body.
In late years, a vehicle weight saving has been promoted due to a rise of environmental awareness, and there is a tendency that an engine room is made smaller and smaller for vehicle interior comfort. Accordingly, there has been a demand for a compact scroll-type fluid machine that is installable, for example, in a small engine room.
On the other hand, the scroll-type fluid machine has a scroll unit that is generally formed in a cantilever structure in which a movable scroll makes an orbital rotation relative to a fixed scroll. In order to downsize the scroll unit and maintain the discharge rate of the scroll unit at the same time, a spiral body has to be made high and is therefore prone to get damaged. For prevention of damage, the spiral body needs to be made with an expensive high-strength material. If any high-strength material is unusable, the spiral body has to be made low in height. This discourages the promotion of downsizing of fluid machines.
To downsize the fluid machines while the spiral body is made high without using a high-strength material, the spiral body needs to be prevented from damage by controlling stress concentration that takes place in the spiral body due to the rotating movement of the movable scroll.
To solve this, Patent Documents 1 and 2 provide a so-called fillet to the base portion and tip end of the spiral body to prevent the spiral body from being damaged. However, the fillets have different curvature radii, and are formed directly in the spiral bodies. This produces the possibility that the fillets are abraded along with the rotating movement of the movable scroll. Moreover, there is created a space having a crescent-shaped cross-section between the base portion and the tip end of the fixed and movable spiral bodies, so that the airtightness of the compression or expansion chamber cannot be maintained, which might lead to considerable deterioration of actuation efficiency of the fluid machine.
If, as described in Patent Document 2, the curvature radius of the fillet is set to be 5 percent or less of wall thickness of the spiral body, it becomes difficult to completely fill the crescent-shaped space because the fillet is too small especially if the fluid machine is of a compact size. Furthermore, there is the possibility that the stress concentration that takes place in the spiral body cannot be successfully controlled.
In Patent Document 3, if the fillet is subjected to surface treatment with a surface treatment material such as a soft metal plating material, the surface treatment material is abraded to have a proper film thickness. The crescent-shaped space might be able to be filled with the fillet. On the other hand, the surface treatment material generally has micron-order thickness, and the thickness thereof does not take abrasion into consideration. If the surface treatment material is too thick, it might fall out along with the orbital rotation of the movable scroll. It is thus difficult to fill the crescent-shaped space even if the fillet is subjected to the surface treatment with a surface treatment material. There is also the possibility that the stress concentration that takes place in the spiral body cannot be successfully controlled.
In Patent Document 4, it is likely that not only the crescent-shaped space but also another space will be created between the base portion of the spiral body and a bottom plate. It is then apparent that airtightness cannot be maintained in the compression or expansion chamber.
To solve this problem, as mentioned in Patent Document 5, if concave and convex chip seals are mounted on the tip end of the spiral body, the crescent-shaped space can be filled with the chip seals. However, a particular attention is given neither to the shape of corners of tip ends of the chip seals nor to the deformation of the chip seals, which is caused by the rotating movement of the movable scroll. For that reason, there still is a problem in completely filling the crescent-shaped space and successfully controlling the stress concentration that takes place in the spiral body.
The present invention provides a scroll-type fluid machine that controls the stress concentration that takes place in fixed and movable spiral bodies, and enhances the airtightness of a compression or expansion chamber of working fluid, which is formed between the spiral bodies, the fluid machine thus being improved in actuation efficiency and yet being downsized.
The scroll-type fluid machine of the invention includes a fixed scroll and a movable scroll each having an end plate and a spiral body integral with the end plate. The spiral body and the end plate come into sliding contact with each other between the fixed and movable scrolls with a chip seal, which is provided to the spiral body, intervening therebetween, thus demarcating a pressure chamber of working fluid, which is formed between the spiral bodies. The spiral body of at least one of the scrolls has a base portion formed in a corner on the end plate side in the form of a concave arc face. The chip seal of the other scroll has a fillet formed of a first convex arc face that comes into sliding contact with the concave arc face on the corner of the tip end of the chip seal.
Preferably, the chip seal has an engaged portion that is engaged with the spiral body, and the engaged portion is situated on a more inner side than the fillet in a width direction of the chip seal.
Preferably, a relationship represented by W2>W1 is satisfied, where the width of the spiral body is W1, and the width of the chip seal is W2.
Preferably, the chip seal has a second convex arc face covering a center end portion of the spiral body, and a relationship represented by R2>R1 is satisfied, where a curvature radius of the first convex arc face is R1, and a curvature radius of a second convex arc face is R2.
Preferably, a relationship represented by (R0−0.1 mm)≦R1≦(R0+0.1 mm) is satisfied, where a curvature radius of a concave arc face is R0, and a curvature radius of the first convex arc face is R1.
Preferably, the first convex arc face of the fillet is provided with an auxiliary rib for reinforcing the sealing between the first convex arc face and the concave arc face at a third convex arc face. A relationship represented by R3≦R0≦R1 is satisfied, where curvature radii of the concave arc face, the first convex arc face and the third convex arc face are R0, R1 and R3, respectively.
Preferably, a plurality of auxiliary ribs are arranged more densely with decreasing distance to the center end portion of the spiral body.
According to the invention, since the chip seal has the fillet formed of the first convex arc face in the corner of the tip end thereof, the stress concentration that takes place in the corner of the tip end of the fixed and movable spiral bodies can be controlled. Moreover, the fillet formed in the first convex arc face of the chip seal of one of the scrolls comes into sliding contact with the base portion formed in the concave arc face of the spiral body of the other scroll, so that the airtightness of the compression or expansion chamber of working fluid, which is formed between the spiral bodies, is enhanced. As a result, the fluid machine is improved in actuation efficiency and can be downsized at the same time.
According to the invention, the chip seal has the engaged portion that is engaged with the spiral body. The engaged portion is situated on a more inner side than the fillet in the width direction of the chip seal. Along with the sliding contact of the fillet with the base portion, the fillet is allowed to be slightly deformed. For this reason, when the fillet is pushed against the base portion, sealability between the spiral bodies, that is, airtightness of the pressure chamber, is further enhanced. This further improves the actuation efficiency of the fluid machine.
According to the invention, the relationship represented by W2>W1 is satisfied, where the width of the spiral body is W1, and the width of the chip seal is W2. It is then possible to reliably protect the tip end of the spiral body with the chip seal and to firmly push the fillet against the base portion. The sealability between the spiral bodies, that is, the airtightness of the pressure chamber, can be further enhanced, thus further improving the actuation efficiency of the fluid machine.
According to the invention, the chip seal has the second convex arc face covering the center end portion of the spiral body, and the relationship represented by R2>R1 is satisfied, where the curvature radius of the first convex arc face is R1, and the curvature radius of the second convex arc face is R2. Accordingly, the chip seal can be formed into a smoothly curved face continuously expanding in the center end portion of the spiral body. This makes it possible to further enhance the sealability between the spiral bodies, that is, the airtightness of the pressure chamber, and thus to further improve the actuation efficiency of the fluid machine.
According to the invention, the relationship represented by (R0−0.1 mm)≦R1≦(R0+0.1 mm) is satisfied, where the curvature radius of the concave arc face is R0, and the curvature radius of the first convex arc face is R1. The curvature radii of the concave arc face and the first convex arc face can therefore be set at values within a proper range that takes account of an elastic deformation of the chip seal. It is then possible to further enhance the sealability between the spiral bodies, that is, the airtightness of the pressure chamber, and thus to further improve the actuation efficiency of the fluid machine.
According to the invention, the first convex arc face of the fillet is provided with the auxiliary rib for reinforcing the sealing between the first convex arc face and the concave arc face at the third convex arc face. The relationship represented by R3≦R0≦R1 is satisfied, where the curvature radii of the concave arc face, the first convex arc face and the third convex arc face are R0, R1 and R3, respectively. It is therefore possible to set the curvature radii of the concave arc face and the first convex arc face at values within a proper range that takes account of the abrasion of the auxiliary rib. In result, the sealability between the spiral bodies, that is, the airtightness of the pressure chamber, is further enhanced, so that the actuation efficiency of the fluid machine is further improved.
According to the invention, since the auxiliary ribs are arranged more densely with decreasing distance to the center end portion of the spiral body, the curvature radii of the concave arc face and the first convex arc face can be set at values within a range that takes account of the abrasion of the auxiliary ribs in the vicinity of the center end portion of the spiral body, where the pressure of the pressure chamber reaches its highest. As a result, the sealability between the spiral bodies, that is, the airtightness of the pressure chamber, is further efficiently enhanced, so that the actuation efficiency of the fluid machine is further improved.
The compressor 1 has a rear housing 2 and a front housing 4. A scroll unit 6 is accommodated in the rear housing 2. The scroll unit 6 is made up of a fixed scroll 8 fixed to the rear housing 2 and a movable scroll 10 fitted to the fixed scroll 8 in an engaged manner. In response to an orbital rotation of the movable scroll 10, the scroll unit 6 continuously carries out a series of processes including the suction, compression, and discharge of the refrigerant in order.
More specifically, a discharge chamber 12 is formed in the rear housing 2 to be located between an end plate thereof and the fixed scroll 8 of the scroll unit 6. The discharge chamber 12 is connectable to a discharge aperture 14 formed in an end plate 8a of the fixed scroll 8, with a reed discharge valve 16 intervening therebetween. The discharge chamber 12 is also connected to a refrigerant circulating path of the refrigeration circuit through a discharge port (not shown) formed in the rear housing 2.
The rear housing 2 is further provided with an intake port (not shown) of the refrigerant. This intake port guides the refrigerant from the refrigerant circulation path and introduces the refrigerant into the rear housing 2. The refrigerant that has been introduced into the rear housing 2 is sucked into the scroll unit 6.
A drive shaft 18 is disposed in the front housing 4. The drive shaft 18 has a large-diameter end 20 and a small-diameter shaft 22. The large-diameter end 20 is rotatably supported by the front housing 4 with a needle bearing 24 intervening therebetween. The small-diameter shaft 22 is rotatably supported by the front housing 4 with a ball bearing 26 intervening therebetween. A lip seal 28 is disposed between the small-diameter shaft 22 and the front housing 4. The lip seal 28 airtightly separates the inside of the front housing 4.
The small-diameter shaft 22 of the drive shaft 18 is protruding from the front housing 4. A protruding end of the small-diameter shaft 22 is interlocked with a drive pulley 30 including a built-in electromagnetic clutch. The drive pulley 30 is rotatably supported by the front housing 4 with a bearing 32 intervening therebetween. The drive pulley 30 is connected via a belt to an output pulley located on the engine side of the vehicle, and is rotated by receiving power from the engine. If the electromagnetic clutch in the drive pulley 30 is ON while the engine is being driven, the drive shaft 18 is rotated together with the drive pulley 30.
A crankpin 34 is protruding from the large-diameter end 20 of the drive shaft 18 in the direction of the movable scroll 10. The crankpin 34 supports a boss 40 of the movable scroll 10 with an eccentric bushing 36 and the needle bearing 38 intervening therebetween. Accordingly, when the drive shaft 18 is rotated, the movable scroll 10 receives the rotation through the crankpin 34 and the eccentric bushing 36 and makes a rotating movement.
A rotation preventing coupling is disposed between the front housing 4 and an end plate 10a of the movable scroll 10. In the case of this embodiment, the rotation preventing coupling is made up of an EM coupling 42. The EM coupling 42 is formed by placing a ball 48 between annular race grooves of ring-like movable and fixed plates 44 and 46.
The fixed scroll 8 has a fixed spiral body 50 integrated with an end plate 8a. The movable scroll 10 also has a movable spiral body 52 integrated with the end plate 10a. Inner and outer faces of the fixed and movable spiral bodies 50 and 52, except for center end portions thereof, are formed of involute faces, and are molded from aluminum alloy such as A4032-T6.
The discharge aperture 14 is positioned close to a center end portion 54 of the fixed spiral body 50. There is secured a certain clearance between the discharge aperture 14 and an inner face of the center end portion 54.
The fixed spiral body 50 is provided with a fixed chip seal 56 in a tip end 50a, and the movable spiral body 52 with a movable chip seal 58 in a tip end 52a. The fixed and movable chip seals 56 and 58 are molded from engineering plastic, such as polyphenylene sulfide (PPS), which has an elastic modulus of approximately a thirtieth part or less of elastic modulus of the fixed and movable spiral bodies 50 and 52 molded from the above-mentioned aluminum alloy.
The fixed spiral body 50 and the end plate 10a are brought into sliding contact with each other with the fixed chip seal 56 intervening therebetween. The movable spiral body 52 and the end plate 8a are brought into sliding contact with each other with the movable chip seal 58 intervening therebetween. Due to the sliding contact between the fixed and movable scrolls 8 and 10, a compression chamber (pressure chamber) 60 of refrigerant is demarcated and located between the fixed and movable spiral bodies 50 and 52, and the above-mentioned series of processes are continuously carried out.
The shape of the base portion 62 of the movable spiral body 52, the fixed chip seal 56, and the tip end 50a of the fixed spiral body 50 of the first embodiment will be described below in detail with reference to a state at the time of the fitting of the movable scroll 10 to the fixed scroll 8 shown in
The movable spiral body 52 is formed to have width W1, and has the base portion 62 in the corner of the end plate 10a side. The base portion 62 has a concave arc face 64 with a curvature radius R0, which is formed by using a cutting tool, such as an end mill, in the step of cutting work of the movable spiral body 52.
The fixed chip seal 56 has substantially the same length as the length of the fixed spiral body 50 in a spiral direction. In the case of the present embodiment, the fixed chip seal 56 has a concave cross-section. In contrast, the fixed spiral body 50 is formed to have a convex cross-section. A convex portion 66 is formed in the tip end 50a of the fixed spiral body 50. The fixed chip seal 56 is engaged with and mounted on the fixed spiral body 50 by fitting to the convex portion 66 of the fixed spiral body 50 a concave portion (engaged portion) 68 forming the concave cross-sectional shape of the fixed chip seal 56 along with the spiral direction of the fixed spiral body 50.
The fixed chip seal 56 has a fillet 70 in each corner of the tip end 56a located on the side brought into sliding contact with the end plate 10a. The fillet 70 is provided with a first convex arc face 72 with a curvature radius R1. The first convex arc face 72 comes into sliding contact with the concave arc face 64 of the base portion 62 in response to the rotating movement of the movable scroll 10.
The fixed chip seal 56 is engaged with a concave portion 68, namely, the fixed spiral body 50 at a portion on a more inner side than the fillet 70 in the width direction of the fixed chip seal 56. Width W2 between outer circumferential surfaces 56c of a lateral portion 56b of the concave portion 68 is larger than at least the width W1 of the fixed and movable spiral bodies 50 and 52. The fixed chip seal 56 has a shape that is gradually widened from the tip end 56a towards the lateral portion 56b.
A relationship below is satisfied among the curvature radius R0 of the concave arc face 64, the curvature radius R1 of the first convex arc face 72, and the curvature radius R2 of the second convex arc face 76.
R2>R1
(R0−0.1 mm)≦R1≦(R0+0.1 mm)
When the above expression is true, it is possible to maintain the sealability between the fillet 70 and the base portion 62, and materialize a smooth rotating movement of the movable spiral body 52, while giving consideration to the moldability of the fixed chip seal 56.
In the compressor 1 of the first embodiment, as described above, the chip seal 56 has the fillet 70 formed of the first convex arc face 72 in the corner of the tip end 56a thereof. This makes it possible to control the stress concentration that takes place in the corners of the tip ends of the fixed and movable spiral bodies 50 and 52. Moreover, since the first convex arc face 72 of the tip end 56a comes into sliding contact with the concave arc face 64 of the base portion 62, the airtightness of the compression chamber 60 of refrigerant, which is formed between the spiral bodies 50 and 52, is enhanced. At the same time, the compression efficiency of the compressor 1 is improved, and thus, the compressor 1 is downsized.
Since the concave portion 68 is situated in a more inner side than the fillet 70 in the width direction of the chip seal 56, the fillet 70 is allowed to be slightly deformed along with the sliding contact of the fillet 70 with the base portion 62. When the fillet 70 is pushed against the base portion 62, the fillet 70 is deformed to fill a minute crescent-shaped space between the fillet 70 and the base portion 62. The sealability between the spiral bodies 50 and 52, that is, the airtightness of the compression chamber 60, can be further enhanced.
The relationship represented by R2>R1 is satisfied, where the curvature radius of the first convex arc face 72 is R1, and that of the second convex arc face 76 is R2. The chip seal 56 can therefore be formed into a smooth curved face continuously expanding in the center end portion 54 of the spiral body 50. In result, the sealability between the spiral bodies 50 and 52, that is, the airtightness of the compression chamber 60, is further enhanced.
The relationship represented by (R0−0.1 mm)≦R1≦(R0+0.1 mm) is satisfied, where the curvature radius of the concave arc face 64 is R0, and that of the first convex arc face 72 is R1. Accordingly, the curvature radii of the concave arc face 64 and the first convex arc face 72 can be set at values within a range that takes account of the elastic deformation of the chip seal 56. It is then possible to further enhance the sealability between the spiral bodies 50 and 52, that is, the airtightness of the compression chamber 60.
As is apparent from
In the fixed spiral body 50, a stepped portion 78 is formed on each side of the convex portion 66 to have width W3 that is a width measured from the convex portion 66. In the fixed chip seal 56, the lateral portion 56b is formed to have width W4.
As described above, the fixed spiral body 50 has the width W1 in the width direction thereof. The fixed chip seal 56 is so formed that distance between the outer circumferential surfaces 56c of the lateral portions 56b is equal to the width W2. The fixed chip seal 56 is so formed that the tip end 56a has thickness T1 in a height direction thereof, and that the lateral portion 56b has thickness T2 in a height direction thereof.
A relationship below is satisfied among the angle θ1 of the base portion 62, the gradual widening angle θ2 of the fixed chip seal 56, the width W1 of the fixed spiral body 50, the width W2 between the outer circumferential surfaces 56c, the width W3 of the stepped portion 78, the width W4 of the lateral portion 56b, the thickness T1 of the tip end 56a, and the thickness T2 of the lateral portion 56b.
W2>W1
(W3−W4)<0.2 mm
θ1<θ2
T2>R1
(R1: the curvature radius of the first convex arc face 72)
T1>1 mm
When the above expression is true, it is possible to maintain the sealability between the fillet 70 and the base portion 62, and materialize a smooth rotating movement of the movable spiral body 52, while giving consideration to the moldability of the fixed chip seal 56.
More specifically, as shown in
As shown in
As shown in
In the compressor 1 of the second embodiment, there is a relational expression of dimension and shape of the base portion 62, the fixed chip seal 56, and the fixed spiral body 50. Especially, the relationship represented by W2>W1 is satisfied, where the width of the spiral body 50 is W1, and the width of the chip seal 56 is W2. It is therefore possible to reliably protect the tip end face 56d of the spiral body 50 by using the chip seal 56, and firmly push the fillet 70 against the base portion 62. This further enhances the sealability between the spiral bodies 50 and 52, that is, the airtightness of the compression chamber 60.
As shown in
A curvature radius R3 of the third convex arc face 84 satisfies a relationship below.
R3≦R0≦R1
(R0: the curvature radius of the concave arc face 64, R1: the curvature radius of the first convex arc face 72)
When the above expression is true, it is possible to maintain the sealability between the fillet 70 and the base portion 62, and materialize a smooth rotating movement of the movable spiral body 52, while giving consideration to the moldability of the fixed chip seal 56.
To be more specific, as shown in
As shown in
As described above, in the compressor 1 of the third embodiment, the auxiliary ribs 86 are arranged in the first convex arc face 72 of the fillet 70. The relationship represented by R3≦R0≦R1 is satisfied, where the curvature radii of the concave arc face 64, the first convex arc face 72, and the third convex arc face 84 are R0, R1, and R3, respectively. Since the fourth convex arc face 88 with the curvature radius R4 substantially equal to R0 is formed, the curvature radius of the concave arc face 64 and that of the first convex arc face 72 can be set at values within a range that takes account of the abrasion of the auxiliary ribs 86. As a consequence, the sealability between the spiral bodies 50 and 52, that is, the airtightness of the compression chamber 60, is further enhanced.
More specifically, when the fillet 70 is pushed against the base portion 62, the wedge-shaped oil film formed in the space created in the compression chamber 60 and the auxiliary ribs 86 work together, and thus completely block a refrigerant leakage passage. Consequently, the sealability between the spiral bodies 50 and 52, that is, the airtightness of the compression chamber 60, can be effectively enhanced.
Since the refrigerant leakage passage can be completely blocked, it is possible to prevent a backward flow of the refrigerant, a decrease in refrigerant pressure, and noises caused by fluctuations of the movable scroll, attributable to the above phenomena.
Since the auxiliary ribs 86 are arranged more densely with decreasing distance to the center end portion 54 of the spiral body 50, the curvature radii of the concave arc face 64 and the first convex arc face 72 can be set at values within the range that takes account of the abrasion of the auxiliary ribs 86 in the vicinity of the center end portion 54 where the pressure of the compression chamber 60 reaches its highest. As a result, the sealability between the spiral bodies 50 and 52, that is, the airtightness of the compression chamber 60, can be further enhanced.
The invention is not limited to the above-described embodiments, and may be modified in various ways.
For example, the chip seal 56 of the invention is not necessarily limited in shape. A convex portion (engaged portion) 92 of the chip seal 90, which is formed to have a convex cross-sectional shape, for example, as shown in
The chip seal 56 and the auxiliary ribs 86 of the invention do not always have to be formed in the entire circumference of the spiral bodies 50 and 52. For example, as shown in
In the above-mentioned case, it is preferable that an outer end 96 of the movable chip seal 58 have an end surface that is formed along a rotating direction (direction of the arrow in
Furthermore, according to the invention, the fillet 70 and the auxiliary ribs 86 may be provided to the chip seal of the spiral body of at least one of the fixed and movable scrolls 8 and 10. It is not always necessary to provide these elements to both the fixed and movable chip seals 56 and 58 or both the fixed and movable spiral bodies 50 and 52.
Needless to say, the invention may be applied not only to scroll compressors but also to any scroll-type fluid machine, such as a scroll expansion machine, in which an expansion chamber is demarcated as a refrigerant pressure chamber.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-121537 | May 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/061854 | 5/24/2011 | WO | 00 | 11/27/2012 |
