Scroll compressor including fixed and orbiting scroll having stepped portions and a surface hardened treatment

Abstract

A scroll compressor comprising a fixed scroll (15); an orbiting scroll (16) supported in a manner allowing for orbiting motion; a discharge port through which a fluid compressed by the two scrolls (15, 16) is discharged; an end plate step portion (16E) provided on an end plate of the orbiting scroll (16) formed so that a height of the end plate is higher on a center portion side in the direction of a spiral wrap and lower on an outer end side; and a wrap step portion (15E) provided on a wall portion of the fixed scroll (15) that corresponds to the end plate step portion (16E) so that a height of the wall portion is lower on the center portion side of the spiral and higher on the outer end side; wherein the orbiting scroll (16) is treated for surface hardening and the fixed scroll (15) is not treated for surface hardening.

Claims

1. A scroll compressor comprising: a fixed scroll comprising a spiral-shaped wall portion disposed in an upright manner on a side surface of an end plate; an orbiting scroll comprising a spiral-shaped wall portion disposed in an upright manner on a side surface of an end plate, the orbiting scroll being supported in a manner capable of orbiting motion with the two wall portions meshing while being prevented from self rotation; a discharge port through which a fluid compressed by the two scrolls is discharged; a single end plate step portion provided on the end plate of one of the two scrolls formed on the side surface of the end plate of the one of the two scrolls so that a height of the end plate of the one of the two scrolls is higher on a center portion side in the direction of the spiral-shaped wall portion of the one of the two scrolls and lower on an outer end side, the single end plate step portion being provided on the end plate of one of the two scrolls that is approximately 180 degrees along a length direction of the spiral-shaped wall portion of the one of the two scrolls spirally inbound from an outer end position where the spiral-shaped wall portion of the one of the two scrolls ends; and a single wall portion step portion provided on the spiral-shaped wall portion of the other of the two scrolls that corresponds to the single end plate step portion so that a height of the spiral-shaped wall portion of the other of the two scrolls is lower on a center portion side of the spiral-shaped wall portion of the other of the two scrolls and higher on an outer end side, wherein the scroll on which the single end plate step portion is provided is treated for surface hardening and the other scroll is not treated for surface hardening.

2. The scroll compressor according to claim 1, wherein Ls/Lout is 0.1 or greater, where Ls is the height of the single end plate step portion on the center portion side of the single end plate step portion of the one of the two scrolls, and Lout is the height of the spiral-shaped wall portion of the other of the two scrolls at the outer end side of the spiral-shaped wall portion of the other of the two scrolls.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a vertical cross-sectional view of a scroll compressor according to an embodiment of the present invention.

(2) FIG. 2 is a horizontal cross-sectional view of how a fixed scroll and an orbiting scroll mesh.

(3) FIG. 3 is an enlarged horizontal cross-sectional view of an end plate step portion and a wrap step portion.

(4) FIG. 4 is an enlarged vertical cross-sectional view of the end plate step portion and the wrap step portion.

(5) FIG. 5 is an enlarged perspective view of the wrap step portion.

(6) FIG. 6 is a vertical cross-sectional view of a scroll compressor according to an embodiment of the present invention.

(7) FIG. 7 is an enlarged vertical cross-sectional view of the end plate step portion and the wrap step portion.

DESCRIPTION OF EMBODIMENTS

(8) Embodiments of the present invention will be described below with reference to the drawings.

(9) As illustrated in FIG. 1, a scroll compressor 1 includes a housing 2 that defines the exterior of the scroll compressor 1. The housing 2 is a cylinder with an open front end side (left side in the drawing) and a sealed rear end side. By fastening and fixing a front housing 3 into the opening on the front end side using bolts 4, a sealed space is formed in the interior of the housing 2, and a scroll compression mechanism 5 and a drive shaft 6 are incorporated in the sealed space.

(10) The drive shaft 6 is rotatably supported by the front housing 3 via a main bearing 7 and an auxiliary bearing 8. A pulley 11, which is rotatably provided on an outer circumferential portion of the front housing 3 via a bearing 10, is connected, via an electromagnetic clutch 12, to a front end portion of the drive shaft 6, which protrudes to the outside from the front housing 3 via a mechanical seal 9, such that motive power can be transmitted from an external source.

(11) A crank pin 13, which is eccentric by a predetermined dimension, is integrally provided on the rear end of the drive shaft 6, and is connected to an orbiting scroll 16 of the scroll compression mechanism 5 described below, via a known slave crank mechanism 14 that includes a drive bushing and a drive bearing that enable a variable rotation radius.

(12) In the scroll compression mechanism 5, a pair of compression chambers 17 are formed between a fixed scroll 15 and the orbiting scroll 16, the pair of compression chambers 17 opposing one another on either side of the center of the fixed scroll 15, as a result of the fixed and orbiting scrolls 15 and 16 being engaged with each other with a 180? phase difference. The scroll compression mechanism 5 is configured to compress a fluid (refrigerant gas) by moving each of the compression chambers 17 from an outer circumferential position toward a center position while gradually reducing the capacity thereof.

(13) A discharge port 18, which discharges compressed gas, is provided in a center section of the fixed scroll 15, and the fixed scroll 15 is provided fixed on a bottom wall surface of the housing 2 via bolts 19. Further, the orbiting scroll 16 is connected to the crank pin 13 of the drive shaft 6 via the slave crank mechanism 14, and is supported by a thrust bearing surface of the front housing 3 via a known self-rotation prevention mechanism 20, such that the orbiting scroll 16 can freely orbit and turn.

(14) An O-ring 21 is provided around the outer circumference of an end plate 15A of the fixed scroll 15. As a result of the O-ring 21 making close contact with the inner circumferential surface of the housing 2, the internal space of the housing 2 is partitioned into a discharge chamber 22 and an intake chamber 23.

(15) The discharge port 18 opens into the discharge chamber 22. The compressed gas from the compression chambers 17 is discharged from the discharge port 18, and then discharged to a refrigeration cycle side therefrom.

(16) An intake port 24, which is provided in the housing 2, opens into the intake chamber 23. A low-pressure gas, which has circulated through the refrigeration cycle, is, through the intake port 24, taken into the intake chamber 23, and then, the refrigerant gas is taken into the interior of the compression chambers 17 from the intake chamber 23.

(17) The pair of the fixed scroll 15 and the orbiting scroll 16 include spiral wraps 15B and 16B integrally disposed in an upright manner on the end plate 15A and an end plate 16A, respectively, as wall portions. A blade tip surface 15C of the fixed scroll 15 is in contact with a blade base surface 16D of the orbiting scroll 16, and a blade tip surface 16C of the orbiting scroll 16 is in contact with a blade base surface 15D of the fixed scroll 15.

(18) An end plate step portion 16E is provided on the end plate 16A of the orbiting scroll 16 such that the height of the end plate 16A transitions from higher on the center portion side to lower on the outer end side in the spiral direction of the spiral wrap 16B. Specifically, as illustrated in FIG. 2, the end

(19) Specifically, as illustrated in FIG. 2, the end plate step portion 16E is provided at a position approximately 180? from the position where the spiral wrap 16B of the orbiting scroll 16 ends.

(20) A wrap step portion 15E is provided on the spiral wrap 15B of the fixed scroll 15 in a manner corresponding to the end plate step portion 16E of the orbiting scroll 16 described above, such that the height of the spiral wrap 15B transitions from lower on the center portion side of the spiral to higher on the outer end side. Specifically, as illustrated in FIG. 2, the wrap step portion 15E is provided at a position 360? from the position where the spiral wrap 15B of the fixed scroll 15 ends. In other words, the end plate step portion 16E is only provided on the end plate 16A of the orbiting scroll 16, and the wrap step portion 15E is only provided on the spiral wrap 15B of the fixed scroll 15. Thus, a wall portion step portion is not provided on the spiral wrap 16B of the orbiting scroll 16 and the tip end of the spiral wrap 16B is an even height. Additionally, an end plate step portion is not provided on the end plate 15A of the fixed scroll 15 making the end plate 15A a flat surface.

(21) FIG. 6 illustrates an embodiment similar to FIG. 1 except that the embodiment of FIG. 6 includes the fixed scroll 15 provided with an end plate step portion having a height lower than the end plate step portion 16E of the orbiting scroll 16, with respect to FIG. 1. FIG. 6 illustrates the scrolls having different height end plate step portions. As illustrated reference numeral 15G denotes an end plate step portion provided on the fixed scroll 15, and reference numeral 16G denotes a wrap step portion provided on the orbiting scroll 16.

(22) As illustrated in FIG. 2, the compression chambers 17 are formed by at least a pair of compression chambers 17A, 17B that oppose one another on either side of the center of the fixed scroll 15.

(23) The fixed scroll 15 and the orbiting scroll 16 described above are made of an aluminum alloy. The fixed scroll 15 is not treated for surface hardening. Accordingly, the aluminum alloy material after cutting and finishing makes the outermost surface layer. The orbiting scroll 16 is treated for surface hardening via a hard alumite treatment.

(24) Accordingly, as illustrated in FIGS. 3 and 4, a hard alumite layer C is formed on the end plate step portion 16E of the orbiting scroll 16, and the wrap step portion 15E of the fixed scroll 15 is not treated for surface hardening. FIG. 4 illustrates, in the configuration shown in FIG. 6, the state in which surface hardening treatment is applied only to the end plate step portion 16E.

(25) When the orbiting scroll 16 orbits relative to the fixed scroll 15, as illustrated in FIG. 3, the end plate step portion 16E and the wrap step portion 15E move relative to one another while in contact. Thus, the curved surface of the tip end of the wrap step portion 15E comes into contact with the curved surface of the end plate step portion 16E, which has a larger radius.

(26) For the surface hardening treatment, at least the area of the orbiting scroll 16 which comes into contact with the fixed scroll 15 is treated, and preferably the area including the entire of the spiral wrap 16B and the entire of the end plate 16A on the side where the spiral wrap 16B is provided is treated. The entire of the orbiting scroll 16 may of course be treated for surface hardening. As shown in the embodiment of FIG. 7, contrary to the embodiment of FIG. 4, the surface hardening treatment is also applied to the spiral wrap 15B of the fixed scroll 15. More specifically, FIG. 7 shows, in the configuration of FIG. 6, that the orbiting scroll 16 has a harder surface hardening treatment than the fixed scroll 15.

(27) Note that the reference sign 31 in FIG. 4 denotes a tip seal for preventing fluid leakage disposed in the groove formed in the tip end of the spiral wrap 15B.

(28) Ls/Lout is 0.05 or greater, where the height of the spiral wrap 15B formed to be higher on the outer end side of the fixed scroll 15, in other words the height on the outer side of the wrap step portion 15E, is Lout (see FIG. 1), and the height of the end plate step portion 16E formed to be higher on the center portion side of the orbiting scroll 16, in other words the height of the step on the center portion side of the end plate step portion 16E, is Ls (see FIG. 1). Additionally, Ls/Lout preferably ranges from 0.05 to 0.3, and more preferably from 0.1 to 0.2.

(29) According to the scroll compressor 1 of the present embodiment, the following effects are achieved.

(30) During orbiting motion with the fixed scroll 15 and the orbiting scroll 16 in mesh, the wrap step portion 15E and the end plate step portion 16E are in contact and move relative to one another. The end plate step portion 16E has a larger contact surface area than the wrap step portion 15E, which has a curved surface with a small radius than that of the end plate step portion 16E. Accordingly, by treating the end plate step portion 16E with hard alumite treatment, wear of the hard alumite layer C can be significantly prevented, thus preventing seizure.

(31) Additionally, the spiral wrap 15B provided with the wrap step portion 15E experiences stress concentration at a root 15F of the wrap step portion 15E. However, hard alumite treatment increases the surface roughness of the surface, thus the fatigue strength of the root 15F of the wrap step portion 15E may be reduced. As such, fatigue strength can be improved by not treating the fixed scroll including the wrap step portion 15E for surface hardening.

(32) The ratio Ls/Lout of the height Ls of the end plate step portion 16E on the center portion side divided by the height Lout of the spiral wrap 15B on the outer end side is 0.05 or greater, preferably ranges from 0.05 to 0.3, and more preferably ranges from 0.1 to 0.2. When Ls/Lout is large, the dimensions of the step are increased, and a decrease in performance may be caused by an increase in the size of the path through which the compressed fluid can leak. However, with such dimensions described above, the decrease in performance can be significantly prevented. When Ls/Lout is small and the dimensions of the step are decreased, the compression ratio is decreased and a decrease in the strength of the spiral wrap due to the height of the spiral wrap on the center portion side being relatively high may be caused. With such dimensions described above, the decrease in the strength can be significantly prevented.

(33) Note that in the present embodiment described above, the end plate step portion 16E is only provided on the end plate 16A of the orbiting scroll 16 and the wrap step portion 15E is only provided on the spiral wrap 15B of the fixed scroll 15. However, in other embodiments of the present invention, the opposite may be the case with an end plate step portion being only provided on the end plate 15A of the fixed scroll 15 and a wrap step portion being only provided on the spiral wrap 16B of the orbiting scroll 16. In such an embodiment, the fixed scroll 15 is treated for surface hardening and the orbiting scroll 16 is not treated for surface hardening.

(34) Additionally, in the present embodiment described above, the scrolls 15, 16 are made of an aluminum alloy. However, in embodiments in which the scrolls 15, 16 are made of cast iron or iron, phosphate coating or diamond-like coating (DLC) can be used for the surface hardening treatment.

(35) In the present embodiment described above, only one scroll was treated for surface hardening. However, in other embodiments, both scrolls may be treated for surface hardening. In such embodiments, the scroll provided with the end plate step portion is treated for surface hardening to have a harder surface than that of the other scroll. For the surface treatment for the harder surface, NiP (nickel phosphorus) plating may be used, and for the other surface, Sn (tin) plating may be used, for example.

(36) Additionally, in another embodiment, a scroll compressor such as that described in Patent Document 1 provided with an end plate step portion on the end plates of both the fixed scroll and the orbiting scroll may be employed. In other words, when the height of the end plate step portion provided on the end plate of the orbiting scroll is greater than that of the end plate step portion provided on the end plate of the fixed scroll, the orbiting scroll is treated for surface hardening and the fixed scroll is not treated for surface hardening. Alternatively, the orbiting scroll is treated for surface hardening treatment to have a harder surface than the fixed scroll.

(37) When the height of the end plate step portion provided on the end plate of the fixed scroll is greater than that of the end plate step portion provided on the end plate of the orbiting scroll, the fixed scroll is treated for surface hardening and the orbiting scroll is not treated for surface hardening. Alternatively, the fixed scroll is treated for surface hardening treatment to have a harder surface than the orbiting scroll.

REFERENCE SIGNS LIST

(38) 1 Scroll compressor 15 Fixed scroll 16 Orbiting scroll 15A, 16A End plate 15B, 16B Spiral wrap 15C, 16C Blade tip surface 15D, 16D Blade base surface 15E Wrap step portion (wall portion step portion) 16E End plate step portion 17 Compression chamber 17A Front compression chamber 17B Back compression chamber