SCROLL TYPE FLUID MACHINE, METHOD AND DEVICE FOR FORMING ELASTIC COATING THEREON

Abstract

A coating solution that contains 10 to 20% by weight of epoxy resin serving as a thermosetting resin, 20 to 30% by weight of MoS.sub.2, and 5 to 10% by weight of graphite, with a remainder thereof constituted by an organic solvent, is sprayed onto a wrap portion side face of an orbiting scroll from a spray nozzle. While spraying the coating solution, the orbiting scroll is rotated on a rotating table and the spray nozzle is moved along a rectilinear movement path toward a radial direction outer side of the orbiting scroll while maintaining an attitude thereof from the start of the spraying process. After applying the coating solution, the coating solution is dried by baking, whereupon a break-in operation is performed. As a result, an elastic coating is formed at a coating thickness that enables elastic deformation in accordance with a clearance between the wrap portion side faces.

Claims

1. A device for forming an elastic coating on a scroll type fluid machine, in which an elastic coating is formed on a side face of a spiral wrap portion, the elastic coating is obtained by dispersing a powdered solid lubricant in a synthetic resin that possesses elasticity and is more flexible than a scroll base material constituting the wrap portion, and is formed at a coating thickness that enables elastic deformation relative to an opposing wrap portion side face of another scroll during an operation while ensuring that a clearance is not generated between the wrap portion side faces is formed on a side face of a spiral wrap portion, the device comprising: a rotation device that includes a rotating table on which a scroll constituted by the wrap portion and an end plate is placed fixedly and a driving device for driving the rotating table, and that rotates the scroll placed fixedly on the rotating table about a spiral center of the wrap portion; a coating solution spraying device having a spray nozzle for spraying a coating solution obtained by dissolving constituent components of the elastic coating in a solvent, onto the rotating scroll toward the wrap portion side face, and a driving device for moving the spray nozzle in a radial direction of the scroll; and a controller that keeps a coating thickness of the coating solution constant by controlling a rotation speed of the rotating table and a movement speed of the spray nozzle.

2. The device for forming an elastic coating on a scroll type fluid machine according to claim 1, wherein the coating solution spraying device comprises a uniaxial system driving device that moves the spray nozzle along a rectilinear path without varying an attitude of the spray nozzle.

3. The device for forming an elastic coating on a scroll type fluid machine according to claim 1, wherein the spray nozzle comprises a slit-shaped discharge port, and a long side of the discharge port has a dimension that corresponds to a height of the wrap portion side face.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 is a partially enlarged sectional view showing a scroll type fluid machine according to a first embodiment of the present invention;

[0046] FIG. 2 is a perspective view showing a method and a device for forming an elastic coating according to the first embodiment of the present invention;

[0047] FIG. 3 is a partial front view showing an elastic coating formation device according to the first embodiment;

[0048] FIG. 4 is a table showing results of a test performed on the elastic coating according to the first embodiment;

[0049] FIG. 5 is a partial front view showing a method and a device for forming an elastic coating according to a second embodiment of the present invention;

[0050] FIG. 6 is a perspective view showing a spray nozzle according to the second embodiment; and

[0051] FIG. 7 is a partial sectional view showing thermal deformation in a scroll type compressor.

BEST MODE FOR CARRYING OUT THE INVENTION

[0052] The present invention will be described in detail below using embodiments shown in the drawings. Note, however, that unless specific description is provided to the contrary, dimensions, materials, shapes, relative arrangements, and the like of constituent components described in the embodiments are not intended to limit the scope of the present invention.

First Embodiment

[0053] A first embodiment of a scroll type fluid machine and a method and a device for forming an elastic coating thereon according to the present invention will now be described on the basis of FIGS. 1 to 4. FIG. 1 shows a meshing portion between a fixed scroll 10 and an orbiting scroll 20 of a non-lubricated scroll type air compressor. In FIG. 1, the aluminum fixed scroll 10 is constituted by a disc-shaped end plate 12 and a spiral wrap portion 14 that stands upright from the end plate 12 in a right-angle direction. The aluminum orbiting scroll 20 is similarly constituted by a disc-shaped end plate 22 and a spiral wrap portion 24 that stands upright from the end plate 22 in a right-angle direction.

[0054] Spiral recessed grooves 16 are engraved in respective end surfaces of the wrap portions 14 and 24, and spiral tip seals 18 are fitted tightly into the recessed grooves 16. A clearance AC between the respective end plates 12, 22 and the respective wrap portions 14, 24 is tightly sealed by the tip seals 18. Further, an elastic coating 28 is formed on a wrap portion side face 24a in order to seal up a clearance RC between the wrap portions 14, 24 such that an enclosed space s is formed between the fixed scroll 10 and the orbiting scroll 20.

[0055] The elastic coating 28 is formed by applying a coating solution containing following components in a following composition to the wrap portion side face 24a using a coating device shown in FIGS. 2 and 3, drying the coating by baking so that the coating is hardened, and then breaking [0056] in the scroll type compressor so that the coating is formed on the wrap portion side face 24a at a coating thickness enabling elastic deformation.

[0057] The coating solution contains 10 to 20% by weight of epoxy resin serving as a thermosetting resin, 20 to 30% by weight of MoS.sub.2, and 5 to 10% by weight of graphite, with the remainder constituted by an organic solvent. Next, a coating method using the coating device shown in FIGS. 2 and 3 will be described.

[0058] In FIGS. 2 and 3, a large number of radiator fins 26 are formed integrally with a back surface of the end plate 22 of the orbiting scroll 20. A rotation device 30 for rotating the orbiting scroll 20 is placed on a floor surface F. The rotation device 30 includes a disc-shaped rotating table 32 having a larger diameter than the end plate 22, a casing 34 attached to a lower portion of the rotating table 32, and a driving device 36 housed in the casing 34 in order to rotate the rotating table 32.

[0059] A coating solution spraying device 40 is fixed onto the floor surface F in the vicinity of the rotation device 30. The coating solution spraying device 40 includes a main body portion 41 having an inbuilt coating solution storage tank, not shown in the drawings, an inbuilt driving device 42 and the like that causes an arm 48, to be described below, to reciprocate in a direction of an arrow, and a guiding frame 44 having a recessed groove 46 along which the arm 48 slides in the direction of the arrow. The recessed groove 46 is disposed in a horizontal direction and has a rectilinear groove shape.

[0060] The arm 48 is engaged to the recessed groove 46 to be free to slide in the direction of the arrow, and thus the arm 48 is moved by the driving device 42 in the direction of the arrow while remaining oriented toward the orbiting scroll 20 side. A downwardly oriented nozzle pipe 50 is attached to a tip end of the arm 48. The aforesaid coating solution is supplied to the nozzle pipe 50 from the main body portion 41 side. A spray nozzle 52 for discharging the coating solution is attached to a lower end of the nozzle pipe 50. The spray nozzle 52 is bent diagonally downward from the nozzle pipe 50 such that a circular coating solution discharge port opposes the wrap portion side face 24a of the orbiting scroll 20.

[0061] The spray nozzle 52 moves while maintaining an identical attitude. In other words, there is no need to provide a mechanism for modifying the attitude of the spray nozzle 52. The arm 48 moves in the horizontal direction along a rectilinear movement path L by moving along the recessed groove 46. A controller 54 controls a rotation angle speed of the rotating table 32 by controlling the driving device 36, and controls a movement speed of the spray nozzle 52 in the direction of the rectilinear movement path L by controlling the driving device 42.

[0062] With this configuration, when the coating solution is to be applied to the wrap portion side face 24a of the orbiting scroll 20, the orbiting scroll 20 is placed on the rotating table 32 and positioned such that a spiral center C of the wrap portion 24 is positioned in a rotary center of the rotating table 32. Next, the spray nozzle 52 is disposed in the spiral center C, whereupon the attitude of the spray nozzle 52 is adjusted such that the coating solution discharge port opposes the wrap portion side face 24a in the spiral center position.

[0063] In this condition, the rotating table 32 is rotated in a direction of an arrow such that the coating solution is discharged from the spray nozzle 52 and sprayed onto the wrap portion side face 24a. The spray nozzle 52 is then moved along the rectilinear movement path L toward a radial direction outer side of the orbiting scroll 20 in while maintaining attitude thereof at the start of the spraying process.

[0064] At this time, the controller 54 controls the movement speed of the spray nozzle 52 to a constant speed, and gradually reduces the rotation angle speed of the rotating table 32 in accordance with the movement of the spray nozzle 52 in an outer peripheral direction of the orbiting scroll 20 from the spiral center C while keeping a distance between the nozzle tip end and the wrap portion side face 24a constant. If the orbiting scroll 20 is rotated at an identical rotation angle speed throughout the coating solution application process, a peripheral speed of the orbiting scroll 20 increases steadily in the outer peripheral direction from the spiral center C. As a result, a coating thickness of the coating solution applied to the wrap portion side face 24a decreases steadily from a central region toward an outside region.

[0065] The controller 54 controls the coating thickness to remain even from the central region to the outside region of the wrap portion side face 24a by gradually reducing the rotation angle speed of the rotating table 32 in accordance with the radial direction movement of the spray nozzle 52. When it is not possible to apply the coating solution to the entire wrap portion side face 24a in a single application, an identical operation is performed again so that the entire wrap portion side face is coated.

[0066] The coating solution need only be applied to the wrap portion side face that contacts the wrap portion 24 of the orbiting scroll 20.

[0067] Following the application process, the coating is dried by baking, whereby the organic solvent evaporates and the epoxy resin hardens. The coating thickness of the elastic coating 28 thus formed on the wrap portion side face 24a of the orbiting scroll 20 is set to exceed the coating thickness that enables elastic deformation during an operation of the scroll type compressor. Following drying by baking, the scroll type compressor is broken in to finish the elastic coating 28 from a coating thickness that causes plastic deformation to the coating thickness that enables elastic deformation in accordance with the clearance RC between the wrap portion side faces. In so doing, the coating thickness of the coating solution does not have to be controlled finely during the application process.

[0068] During the break-in operation, the elastic coating 28 is finished to the coating thickness that enables elastic deformation from the coating thickness that causes plastic deformation either by plastically deforming the elastic coating 28 on the wrap portion side face 24a or by scraping away or wearing down a surface of the elastic coating 28 on the opposing wrap portion side face.

EXAMPLES

[0069] A scroll type air compressor including the elastic coating 28 having the components and composition described above on one side face of the wrap portion 24 was operated, whereupon a damaged condition of the wrap portion 24 and a sealing condition between the wrap portion side faces were inspected. Results are shown in FIG. 4. In the inspection, the clearance RC between the wrap portion side faces of the fixed scroll 10 and the orbiting scroll 20 was changed variously, the elastic coating 28 was formed at different coating thicknesses by performing the coating formation process described above in accordance with the clearances RC, and the inspection was performed using the formed elastic coatings 28.

[0070] It is evident from FIG. 4 that when the elastic coating 28 is between 30 and 80 m, contact between the opposing wrap portions 24 is alleviated, and therefore damage to the wrap portions can be prevented and a favorable sealing condition can be maintained between the wrap portion side faces of the two wrap portions. It was found that when the coating thickness is less than 30 m, a large impact is generated when the wrap portions collide, as a result of which the wrap portions may be damaged. It was also found that when the coating thickness equals or exceeds 90 m, the elastic coating 28 is more likely to peel.

[0071] Further, it was discovered that when a composition range of the epoxy resin is smaller than the aforesaid composition range, an adhesive force of the elastic coating 28 relative to the wrap portion side face decreases, and when the composition range of the epoxy resin is greater than the aforesaid composition range, the elasticity of the elastic coating 28 decreases. It was therefore learned that the adhesive force and the elasticity of the elastic coating can be optimized within the aforesaid composition range of the epoxy resin. Further, it was found that when the composition range of the solid lubricant is smaller than the aforesaid composition range, the lubricating property and the sliding property relative to the wrap portion side face decrease, and when the composition range of the solid lubricant is greater than the aforesaid composition range, the strength of the elastic coating and the adhesive force thereof relative to the wrap portion side face decrease. It was therefore learned that the strength, lubricating property, sliding property, and adhesive strength of the elastic coating relative to the wrap portion side face can be optimized within the aforesaid composition range of the solid lubricant.

[0072] Note that polytetrafluoroethylene (PTFE) may be added to the epoxy resin within the range of the aforesaid composition range. Further, a solid lubricant constituted by MoS.sub.2 alone may be used as the solid lubricant within the range of the aforesaid composition range.

[0073] MoS.sub.2 and graphite are self-lubricating, and therefore, when the present invention is applied to a non-lubricated scroll type air compressor, as in this embodiment, a lubricating property can be maintained between the wrap portions even without the use of lubricating oil.

[0074] Further, by employing the coating device and coating method shown in FIGS. 2 and 3, the elastic coating 28 can be formed on the wrap portion side face 24a of the orbiting scroll 20 at an even coating thickness from the spiral center C to the outside end. Moreover, the movement speed of the spray nozzle 52 remains constant, and therefore even thickness of the elastic coating 28 can be realized by simple control in which only the rotation angle speed of the rotating table 32 is controlled. Since complicated control is not required, a simple and inexpensive control device can be used as the control device.

[0075] Furthermore, during the application process, the spray nozzle 52 is simply moved rectilinearly along the rectilinear movement path L while maintaining attitude thereof at the start of the application process. Therefore, a uniaxial system driving mechanism may be used as a mechanism for driving the spray nozzle 52. As a result, the configuration of the driving device 42 of the coating solution spraying device 40 can be simplified, enabling a reduction in cost.

[0076] Note that in the first embodiment, an operation start position of the spray nozzle 52 is set as the spiral center C of the wrap portion 24, and once the coating solution spraying process has begun, the spray nozzle 52 is moved in the outer peripheral direction of the orbiting scroll 20. Instead, however, the start position of the spray nozzle 52 may be set as the outside end of the wrap portion 24, and once the coating solution spraying process has begun, the spray nozzle 52 may be moved toward the spiral center C side of the orbiting scroll 20. In this case, the rotation angle speed of the rotating table 32 is gradually increased in accordance with the movement speed of the spray nozzle 52.

[0077] In the first embodiment, the coating solution spraying device 40 that moves the arm 48 using a uniaxial system driving mechanism is employed, but instead, the arm 48 may be moved three-dimensionally using a multiaxial system driving mechanism.

Second Embodiment

[0078] Next, a second embodiment of the coating method according to the present invention will be described using FIGS. 5 and 6. A discharge port 58 of a spray nozzle 56 takes the shape of an elongated slit extending in a vertical direction. A dimension h.sub.2 of a long side of the discharge port 58 is set to be substantially identical to a height dimension h.sub.1 of the wrap portion side face 24a. Hence, when the coating solution is discharged from the discharge port 58, the coating solution can be applied to the entire region of the wrap portion side face 24a in a height direction extending from a connecting portion connected to the end plate 22 to a tip end portion in a single application. All other configurations of the coating device are identical to the first embodiment.

[0079] In the first embodiment and the second embodiment, examples in which the elastic coating is formed on the wrap portion of the orbiting scroll were described, but the elastic coating may be formed on the wrap portion of the fixed scroll instead. Further, the present invention may be applied to other scroll type fluid machines.

INDUSTRIAL APPLICABILITY

[0080] According to the present invention, an elastic coating can be formed easily on a wrap portion side face of a scroll type fluid machine while maintaining a tight seal between wrap portion side faces and preventing seizure, galling, wear, contact damage, and the like between wrap portions.