Scroll compressor for a vehicle air-conditioning system having spiral wall including conical cut

Abstract

A scroll compressor for a motor vehicle air-conditioning system includes a compressor housing, two interleaving spirals within the compressor housing, of which one spiral is stationary and the other spiral is movable eccentrically on a circular orbit, whereby the volume of compression chambers formed between the spirals changes cyclically and refrigerant is suctioned in and compressed; at least one refrigerant outlet port for ejecting the compressed refrigerant in a wall, frontal to the spirals, of the compressor housing in the center of the stationary spiral, wherein in the spiral end region on the inner end of at least one of the two spirals the concave side of the spiral wall is provided with a cut that has the form of a cone segment with concave curvature, decreasing from the upper end in the direction toward the lower end of the spiral wall.

Claims

1. A scroll compressor for a motor vehicle air-conditioning system, comprising: a compressor housing, two interleaving spirals within the compressor housing, of which one spiral is stationary and the other spiral is movable eccentrically on a circular orbit, whereby the volume of compression chambers formed between the two interleaving spirals changes cyclically and refrigerant is suctioned in and compressed; at least one refrigerant outlet port for ejecting the compressed refrigerant in a wall, frontal to the two interleaving spirals, of the compressor housing in the center of the stationary spiral, wherein a spiral wall of the two interleaving spirals includes an inner circumferential surface located radially inside with respect to a longitudinal central axis of the spiral wall, and an outer circumferential surface located radially outward with respect to the longitudinal central axis of the spiral wall, a tip inner end having a surface that interconnects the inner circumferential surface and the outer circumferential surface, wherein in a spiral end region that includes the tip inner end of at least one of the two interleaving spirals the inner circumferential surface of the spiral wall is provided with a conical cut formed of a cone segment with a concave curvature, decreasing from an upper end of the spiral wall in a direction toward a lower end of the spiral wall, wherein the conical cut includes a first oblique edge at least partially positioned along the surface of the tip inner end and a second oblique edge that is spaced apart from the surface of the tip inner end, wherein the first oblique edge of at least one of the two interleaving spirals converges towards the lower end of the spiral wall with the second oblique edge of the conical cut that extends from an upper end of the spiral wall down to the lower end, the first oblique edge and the second oblique edge converging at an angular point on a corner of the tip inner end at the lower end, wherein an absolute value of a slope of the first oblique edge positioned at the tip inner end has a greater absolute slope value than an absolute slope value of the second oblique edge.

2. A scroll compressor as in claim 1, wherein the conical cut is developed such and the first oblique edge is inclined at such an angle that the thickness of the spiral wall at the lower end in a region of the conical cut is the same as in regions of the spiral wall outside of the conical cut.

3. A scroll compressor as in claim 2, wherein the stationary spiral is provided with the conical cut.

4. A scroll compressor as in claim 2, wherein the moveable spiral is provided with the conical cut.

5. A scroll compressor as in claim 2, wherein the conical cut has already been worked in during the production of the unmachined part of the moveable spiral.

6. A scroll compressor as in claim 1, wherein the stationary spiral is provided with the conical cut.

7. A scroll compressor as in claim 1, wherein the moveable spiral is provided with the conical cut.

8. A scroll compressor as in claim 1, wherein the conical cut has already been worked in during production of the unmachined part of the moveable spiral.

9. A scroll compressor as in claim 1, wherein the conical cut has been generated by milling using a conical milling tool.

10. A scroll compressor as in claim 1, wherein the conically formed cut extends over the entire height of the spiral wall.

11. A scroll compressor as in claim 10, wherein the stationary spiral is provided with the conical cut.

12. A scroll compressor as in claim 10, wherein the moveable spiral is provided with the conical cut.

13. A scroll compressor as in claim 10, wherein the conical cut has already been worked in during the production of the unmachined part of the spiral.

14. A scroll compressor as in claim 10, wherein the conical cut has been generated by milling using a conical milling tool.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Further details, characteristics and advantages of implementations of the invention are evident in the following description of embodiment examples with reference to the associated drawing. Therein depict:

(2) FIG. 1A: a prior art spiral of a scroll compressor with a prismatic cut form of the spiral end region,

(3) FIG. 1B: a spiral of a scroll compressor with an obliquely cut form of the spiral end region,

(4) FIG. 2A: a top view onto a spiral of a scroll compressor with an obliquely cut form of the spiral end region,

(5) FIG. 2B: a cross section of the spiral along a sectional plane in the spiral end region,

(6) FIG. 2C: a schematic representation of the generation of the oblique cut of the spiral end region by means of a conical milling tool,

(7) FIG. 2D: a perspective representation of the spiral with the cut generated by means of the conical milling tool in the spiral end region,

(8) FIG. 3: a schematic representation of a scroll compressor with a conically cut spiral end of the orbiting spiral, and

(9) FIG. 4: a pressure profile diagram with comparison curves.

DETAILED DESCRIPTION

(10) FIG. 1A shows a spiral of a scroll compressor with a prismatically cut form of the spiral end region according to prior art. In its spiral end region the depicted spiral comprises a vertical cut denoted as prismatic. The wall thickness in the spiral end region is significantly less than in the region of the remaining spiral.

(11) FIG. 1B shows an embodiment example according to the invention of a spiral 1 of a scroll compressor, stated more precisely of its spiral end region. In the spiral end region at the inner end 2 of spiral 1 the concave side 3 of the spiral wall is provided with a cut 4 which has the generated shell form of a concavely curved surface of a cone segment. Through the conical form of the cut 4 an oblique edge 5 results on the inner end 2 of spiral 1, wherein the oblique edge 5 extends over the entire height of the spiral wall. Consequently, the volume of the cut 4, in accordance with its oblique shape, is distributed from its upper end 6 to the lower end 7 of the spiral wall. The cut 4 is herein developed such and, in particular, the oblique edge 5 is inclined at such angle that at the lower end 7 of the spiral 1 the wall thickness of the spiral is maintained. Stated differently, the thickness of the spiral wall at its lower end 7, even in the region of cut 4, is of the same magnitude as in regions of spiral 1 outside of the cut 4. The mechanical strength, rigidity and loading resistance of the spiral is not negatively affected in the region of the cut 4. Since the cut extends from the upper end 6 to the lower end 7 of the spiral, in the generation of the conical cut 4, less material needs to be cut off in the longitudinal direction of the spiral 1 at a volume of the material cut from the spiral that is unchanged compared to a prismatic cut of prior art.

(12) As FIG. 1B shows, the cut 4 is formed conically such that the oblique edge 5 and a second oblique edge 8 of cut 4, that extends from the upper end 6 of the spiral wall down to the lower end 7, converge in an angular point 9 on the corner of the inner end 2 at the lower end 7 of the spiral 1.

(13) FIG. 2A shows a top view onto a spiral 1 of a scroll compressor with a conical cut 4. FIG. 2A shows at the same time the sectional plane A for the cross sectional representation following in FIG. 2B, which extends through the cut 4 in the spiral end region at the inner end 2 of spiral 1. The cross section in FIG. 2B includes the spiral wall starting from the bottom at the lower end 7 up to the upper end 6. The cross sectional depiction shows in particular the oblique orientation of cut 4 at an angle α with respect to an axis 10 that extends parallel to the non-cut spiral wall.

(14) In FIG. 2C the manner in which the conical cut 4 at the inner end 2 of spiral 1 can be generated is shown schematically. The concave side of the spiral wall in the spiral end region, i.e. at the inner end 2 of spiral 1, is worked with a conical milling tool 11 whose diameter tapers downwardly. The conical milling tool 11 is set into the spiral center in the direction of the tool axis 12 (cone axis) and, with a portion of its conically convex circumferential surface, contacts the spiral end region along its tool path 13 which is sketched out in FIG. 2C in a dashed line. The movement of the convex conical milling tool 11 along the tool path 13 leads to a corresponding concave cut 4 on the inside 3 of the spiral wall at the inner end 2 of spiral 1, as is shown in FIG. 2D. This means that this cut 4 has the shape of a cone segment with concave curvature which decreases from the upper end 6 down to the, not shown, lower end of the spiral wall.

(15) In FIG. 3 is shown schematically a scroll compressor 14 comprising interleaving spirals 1.1; 1.2, of which one spiral 1.1 is stationary and the other spiral 1.2 is movable eccentrically on a circular orbit, whereby the volume of compression chambers 15.1, 15.1′; 15.2, 15.2′; 15.3 formed between the spirals 1.1; 1.2 changes cyclically and refrigerant is suctioned in and compressed. FIG. 3 shows herein the scroll compressor 14 at a certain rotational angle of the orbiting spiral 1.2, in which the two spirals 1.1; 1.2 are at several contact points 16.1, 16.2; 16.3 in the radial direction in contact with one another. Although the spiral end regions of both spirals 1.1; 1.2 are closely opposite to one another, due to the conical cut 4 that is developed over the entire height of the spiral wall, there is no radial contact between the two spirals 1.1; 1.2 at this rotational angle. Since therewith one of the radial contacts is eliminated, the redundancy is reduced and consequently the leak-tightness of the outer compression chambers 15.1, 15.1; 15.2, 15.2′ at lower pressures is improved. Moreover, contact forces between the spirals 1.1; 1.2 are thereby gradually shifted to the outer windings where the curvature is lesser and the radius greater. This reduces the wear considerably.

(16) FIG. 4 shows a pressure profile diagram in which the pressure course in a compressor as a function of the rotational angle when applying a cut developed according to prior art at an inner spiral end is compared to the pressure course in a compressor when developing a conical cut on one of the spiral ends. In the pressure profile of the compression curve is evident in a scroll compressor with a conical cut on one of the inner spiral ends a markedly lower leakage during the compression process in comparison to a scroll compressor in which an inner spiral end of one of the two spirals has a prismatic cut. A shoulder in the curve also shows clearly the decrease of the overpressure in the rotational angle region about the union angle, i.e. about the angle in which the complementary compression chambers 15.2; 15.2′, cf. FIG. 3, combine to form a central compression chamber.

LIST OF REFERENCE SYMBOLS

(17) 1 Spiral 1.1 Stationary spiral 1.2 Orbiting spiral 2 Inner end of spirals 1.1 or 1.2 3 Concave side of spiral wall 4 Cut 5 Oblique edge 6 Upper end of spiral wall 7 Lower end of spiral wall 8 Second oblique edge 9 Angular point 10 Axis (parallel to the non-cut spiral wall) 11 Conical milling tool 12 Tool axis 13 Tool path 14 Scroll compressor 15.1 Compression chamber 15.1′ Compression chamber 15.2 Compression chamber 15.2′ Compression chamber 15.3 Compression chamber 16.1 Contact point (radial contact) 16.2 Contact point (radial contact) 16.3 Contact point (radial contact) α Orientation angle of cut with respect to axis 10 A Sectional plane