Scroll member, method of manufacturing same, compression mechanism and scroll compressor

A method of manufacturing a scroll member includes a casting step and a cutting step. In the casting step an iron casting having a spiraling part is formed. In the cutting step, the iron casting obtained in the casting step is cut to obtain a final shape of the scroll member. Preferably the iron casting obtained in the casting step has a fixing part with the spiraling part extending from one side and a protruding part extending from an opposite side. A specified portion of the spiraling part, a central portion of the fixing part and/or the protruding part has a larger dimension before the cutting step is performed than after the cutting step is performed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. National stage application claims priority under 35 U.S.C. §119(a) to Japanese Patent Application No. 2007-092273 filed in Japan on Mar. 30, 2007, the entire contents of which are hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a scroll member and a method for manufacturing the same.

BACKGROUND ART

A scroll-type compressor comprises a compression mechanism for compressing a refrigerant. The compression mechanism has a fixed scroll and an orbiting scroll.

Methods for forming cast iron by using a metal die, for example, have been used conventionally as methods for manufacturing fixed scrolls, orbiting scrolls, and other scroll members. In conventional methods, the cast iron has been formed into substantially the same shape as the finished products of scroll members (see Japanese Laid-open Patent Application No. 2005-36693, for example).

SUMMARY OF THE INVENTION

Technical Problem

However, if the cast iron is formed into the same shape as the finished products of the scroll members, the portion extending in a spiraling formation of low thickness is easy to cool due to a low heat capacity, and the hardness cannot be increased. Therefore, when the compression mechanism is driven, there is a danger that this portion will suffer wear or deformation.

The strength of this portion can be increased by increasing the thickness of this portion, but this is undesirable because the size of the compression mechanism is increased.

The present invention is made in view of the circumstances described above, and an object thereof is to reduce wear and deformation in a scroll member.

Solution to Problem

A method for manufacturing a scroll member according to a first aspect of the present invention is a method for manufacturing a scroll member used in a compression mechanism installed in a scroll compressor, the method comprising a step (a) and a step (b). In step (a), cast iron is formed and an iron casting is obtained, the iron casting having a spiraling part extending in a spiraling formation. In step (b), the iron casting obtained in step (a) is cut and a scroll member is obtained. The iron casting obtained in step (a) is designed so that a dimension in a specified portion of the spiraling part is greater than the dimension of the same portion after step (b) is performed. The specified portion is positioned at least at an end near a center of the spiral.

A method for manufacturing a scroll member according to a second aspect of the present invention is the method for manufacturing a scroll member according to the first aspect, wherein the specified portion is a portion of the spiraling part which extends around the center from the end to a position located anywhere from a half circle up to a full circle.

A method for manufacturing a scroll member according to a third aspect of the present invention is the method for manufacturing a scroll member according to the first or second aspect, wherein the compression mechanism includes two scroll members, one being an orbiting scroll and the other being a fixed scroll provided with a hole in the center. In the orbiting scroll, the specified portion after step (b) is performed encircles the hole of the fixed scroll when the orbiting scroll has been incorporated into the compression mechanism.

A method for manufacturing a scroll member according to a fourth aspect of the present invention is the method for manufacturing a scroll member according to any of the first through third aspects. The scroll member is a fixed scroll provided with a hole in the center. In the fixed scroll, the specified portion after step (b) is performed encircles the hole.

A method for manufacturing a scroll member according to a fifth aspect of the present invention is the method for manufacturing a scroll member according to any of the first through fourth aspects, wherein the dimension is the thickness of the spiraling part.

A method for manufacturing a scroll member according to a sixth aspect of the present invention is the method for manufacturing a scroll member according to the fifth aspect, wherein the iron casting obtained in step (a) further includes a fixing part for fixing the spiraling part. The height of the specified portion from the fixing part is greater than the height after step (b) is performed.

A method for manufacturing a scroll member according to a seventh aspect of the present invention is the method for manufacturing a scroll member according to any of the first through fourth aspects, wherein the iron casting obtained in step (a) further includes a fixing part for fixing the spiraling part. The dimension is the height of the spiraling part from the fixing part.

A method for manufacturing a scroll member according to an eighth aspect of the present invention is the method for manufacturing a scroll member according to the fifth or sixth aspect, wherein the iron casting obtained in step (a) further includes a fixing part for fixing the spiraling part. In the specified portion, the dimension of a base portion fixed to the fixing part is greater than the dimension after step (b) is performed.

A method for manufacturing a scroll member according to a ninth aspect of the present invention is the method for manufacturing a scroll member according to the eighth aspect, wherein the dimension of the base portion decreases towards a distal end of the spiraling part as viewed from the fixing part.

A method for manufacturing a scroll member according to a tenth aspect of the present invention is the method for manufacturing a scroll member according to the ninth aspect, wherein the dimension of a portion near the distal end in the specified portion is also greater than the dimension after step (b) is performed. The thickness of the spiraling part decrease towards the distal end from the base.

A method for manufacturing a scroll member according to an eleventh aspect of the present invention is the method for manufacturing a scroll member according to the tenth aspect, wherein a side surface of the spiraling part is a flat surface in both the base portion and the portion near the distal end. The side surface of the base portion is inclined with respect to the side surface of the portion near the distal end.

A method for manufacturing a scroll member according to a twelfth aspect of the present invention is the method for manufacturing a scroll member according to any of the eighth through eleventh aspects, wherein the base portion of the specified portion, the portion near the distal end, and the portion of the fixing part in the spiraling part side are all cut in step (b). The thickness at which the base portion is cut is greater than both of the thicknesses with which the portion near the distal end and the portion of the fixing part are cut.

A method for manufacturing a scroll member according to a thirteenth aspect of the present invention is a method for manufacturing a scroll member used in a compression mechanism installed in a scroll compressor, the method comprising a step (a) and a step (b). In step (a), cast iron is formed and an iron casting is obtained having a spiraling part extending in a spiraling formation and a fixing part for fixing the spiraling part. In step (b), the iron casting obtained in step (a) is cut and the scroll member is obtained. The iron casting obtained in step (a) is designed so that in the fixing part, a thickness of the portion near a center of the spiral is greater than the thickness of the same portion after step (b) is performed.

A method for manufacturing a scroll member according to a fourteenth aspect of the present invention is the method for manufacturing a scroll member according to the thirteenth aspect, wherein the iron casting obtained in step (a) has a protruding part fixed to the fixing part on the side opposite the spiraling part. The protruding part extends in a cylindrical shape from the edge of the portion near the center of the fixing part towards the side opposite the spiraling part.

A method for manufacturing a scroll member according to a fifteenth aspect of the present invention is a method for manufacturing a scroll member used in a compression mechanism installed in a scroll compressor, the method comprising a step (a) and a step (b). In step (a), cast iron is formed and an iron casting is obtained having a spiraling part extending in a spiraling formation, a fixing part for fixing the spiraling part, and a protruding part fixed near a center of the fixing part on the side opposite the spiraling part. In step (b), the protruding part of the iron casting obtained in step (a) is cut into a cylindrical shape open only in the side opposite the spiraling part.

A method for manufacturing a scroll member according to a sixteenth aspect of the present invention is the method for manufacturing a scroll member according to any of the first through fifteenth aspects, wherein the cast iron is formed by semi-molten die casting in step (a).

A scroll member according to a seventeenth aspect of the present invention is the scroll member (26) manufactured by the method according to any of the first through sixteenth aspects. After step (b) is performed, the ratio of the height of the spiraling part from the fixing part with respect to the thickness of the spiraling part is 8.5 or greater.

A scroll member according to an eighteenth aspect of the present invention is the scroll member according to the seventeenth aspect, wherein the hardness of the base portion fixed to the fixing part is HRB 95 or greater in the portion near the end at the center of the spiral in the spiraling part.

A compression mechanism according to a nineteenth aspect of the present invention comprises the scroll member according to the seventeenth or eighteenth aspect as either one or both of an orbiting scroll and a fixed scroll.

A scroll compressor according to a twentieth aspect of the present invention comprises the compression mechanism according to the nineteenth aspect.

A scroll compressor according to a twenty-first aspect of the present invention is the scroll compressor according to the twentieth aspect, wherein refrigerant including carbon dioxide as a main component is compressed.

Advantageous Effects of Invention

With the method for manufacturing a scroll member according to the first aspect, the dimension of the end portion at the center of the spiral in step (a) is made to be larger than the dimension after step (b) is performed, whereby the heat capacity is increased in the end portion where stress readily concentrates. Consequently, this end portion is resistant to cooling even after being formed. The hardness of this portion can thereby be increased, and wear in the scroll member can thereby be reduced.

With the method for manufacturing a scroll member according to the second aspect, the hardness can be increased in the portion where stress readily concentrates near the center. Consequently, wear in the scroll member can be reduced.

With the method for manufacturing a scroll member according to the third aspect, the hardness can be increased in the portion where stress readily concentrates near the hole. Consequently, wear in the orbiting scroll can be reduced.

With the method for manufacturing a scroll member according to the fourth aspect, the hardness can be increased in the portion where stress readily concentrates near the hole. Consequently, wear in the fixed scroll can be reduced.

With the method for manufacturing a scroll member according to the fifth aspect, the hardness of the spiraling part can be increased.

With the method for manufacturing a scroll member according to the sixth or seventh aspect, it is possible to increase the hardness of the portion at the distal end of the spiraling part when the spiraling part is viewed from the fixing part.

With the method for manufacturing a scroll member according to the eighth aspect, the thickness of the base portion of the specified portion is made to be greater than the thickness after step (b) is performed, whereby the heat capacity is increased in the base portion where stress readily concentrates. Consequently, the base portion is resistant to cooling even after being formed. The hardness of the base portion can thereby be increased, and deformation in the spiraling part after machining can thereby be prevented.

With the method for manufacturing a scroll member according to the ninth aspect, the thickness of the base portion decreases towards the distal end, whereby the iron casting is easily removed from the metal die in the direction opposite the distal end in cases in which the iron casting is formed using a metal die in step (a). This is because friction is reduced between the metal die and the base portion of the spiraling part.

With the method for manufacturing a scroll member according to the tenth aspect, the iron casting is easily removed from the metal die. Moreover, since the thickness of the portion near the distal end is small, a smaller amount is cut in comparison with the base portion, and machining of the iron casting is thereby made easier.

With the method for manufacturing a scroll member according to the eleventh aspect, since the side surface of the spiraling part has a tapered shape, it is even easier to remove the iron casting from the metal die.

With the method for manufacturing a scroll member according to the twelfth aspect, the heat capacity of the base portion can be made greater than the heat capacity of the other portions because the iron casting obtained in step (a) is designed so that the dimension of the base portion of the spiraling part is greater than the dimensions of the portion near the distal end of the specified portion and the portion on the spiraling part side of the fixing part. Consequently, the hardness of the base portion can be made greater than the other portions.

With the method for manufacturing a scroll member according to the thirteenth aspect, the thickness of the portion near the center of the fixing part in step (a) is made greater than the thickness after step (b) is performed, whereby the heat capacity of this portion is increased. Consequently, this portion is resistant to cooling even after being formed, and the portion of the spiraling part near the center is resistant to cooling. The hardness of the portion near the center of the spiraling part can thereby be increased, and wear in the scroll member can be reduced.

With the method for manufacturing a scroll member according to the fourteenth aspect, the scroll member can be used as an orbiting scroll. The protruding part is used as a bearing, and slidably supports the crankshaft for rotating the orbiting scroll.

With the method for manufacturing a scroll member according to the fifteenth aspect, the protruding part is also formed in step (a), whereby the iron casting is thicker near the center. Consequently, the center vicinity of the iron casting is increased in heat capacity and more resistant to cooling even after being formed, and the portion near the center in the spiraling part is thereby resistant to cooling. The hardness of the portion near the center of the spiraling part can thereby be increased, and wear in the scroll member can be reduced. Moreover, the scroll member can be used as an orbiting scroll by performing step (b). The protruding part after machining is used as a bearing, and slidably supports the crankshaft for rotating the orbiting scroll.

With the method for manufacturing a scroll member according to the sixteenth aspect, the strength of the resulting scroll member is increased by using semi-molten die casting.

With a scroll member according to the seventeenth aspect, since the scroll member is manufactured by the method of any of first through sixteenth aspects, the spiraling portion has high strength, and the spiraling part is thereby resistant to deformation even if the ratio of height to thickness is 8.5 or greater. Consequently, the scroll member can be reduced in size.

With the scroll member according to the eighteenth aspect, the strength of the base portion of the portion near the center can be increased to HRB 95 or greater, and strength can be increased by semi-molten die casting. Therefore, damage in the spiraling part due to stress can be prevented even if the ratio of height to thickness in the spiraling part is 8.5 or greater.

With the compression mechanism according to the nineteenth aspect, damage in the spiraling part due to stress can be prevented because the hardness and strength of the portion near the center of the spiraling part are higher than those of the other portions. Consequently, the compression mechanism does not fail readily.

With the scroll compressor according to the twentieth aspect, since the compression mechanism does not readily fail, the scroll compressor also does not readily fail.

With the scroll compressor according to the twenty-first aspect, since the compression mechanism has high strength, the scroll compressor does not readily fail even in cases in which carbon dioxide is used.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a drawing schematically depicting a scroll compressor1according to an embodiment of the present invention. A direction91is shown inFIG. 1, and hereinbelow the distal side of the arrow of the direction91is referred to as “upper side,” while the opposite side is referred to as “lower side.”

The scroll compressor1comprises a case11and a compression mechanism15. The case11has a cylindrical shape and extends along the direction91. The compression mechanism15is housed within the case11.

The compression mechanism15has a fixed scroll24and an orbiting scroll26and compresses refrigerant. A refrigerant containing, e.g., carbon dioxide as a primary component can be used. Both the fixed scroll24and the orbiting scroll26can be conceived as the scroll member used in the compression mechanism15.

The fixed scroll24includes a panel24aand a compression member24b. The panel24ais fixed to an internal wall11aof the case11, and the compression member24bis linked to the underside of the panel24a. The compression member24bextends in a spiraling shape, and a groove24cis formed along the spiral therein. A hole41is provided in the central vicinity of the panel24a. Refrigerant compressed by the compression mechanism15is discharged through the hole41.

The orbiting scroll26has a panel26aand a compression member26b. The compression member26bis linked to the top side of the panel26aand extends in a spiraling formation.

The compression member26bis accommodated within the groove24cof the fixed scroll24. In the compression mechanism15, a space40between the compression member24band the compression member26bis hermetically sealed by the panels24a,26aand is thereby used as a compression chamber.

In relation to the method for manufacturing a scroll member, the method for manufacturing the orbiting scroll26is described hereinbelow in the first and second embodiments, and the method for manufacturing the fixed scroll24is described in the third embodiment. In the fourth embodiment, the scroll members obtained by the above manufacturing methods are described.

First Embodiment

The method for manufacturing the orbiting scroll26, which is a scroll member, comprises a step (a) and a step (b).

In step (a), cast iron is formed and an iron casting is obtained. For example, an iron casting of high strength can be obtained by forming cast iron by semi-molten die casting. In step (b), the iron casting obtained in step (a) is cut to obtain the orbiting scroll26.

FIGS. 2 and 3schematically depict an iron casting261obtained in step (a). The iron casting261has a fixing part261aand a spiraling part261b. The spiraling part261bis fixed to the fixing part261aand extends in a spiraling formation around a center9. InFIGS. 2 and 3, the shape of the spiraling part261bobtained after step (b) is performed is shown by single-dashed lines.

In the iron casting261obtained in step (a), the dimension of a specified portion of the spiraling part261bis greater than the dimension of this portion after step (b) is performed (Mode A).

Specifically, in a portion2612of an end2611of the spiral at the center9inFIG. 2, the thickness d1is greater than the thickness h1of the portion2612after step (b) is performed. In other words, in the aforementioned Mode A, the portion2612is used as the specified portion, and the thickness d1of the portion2612is used as the dimension.

In the spiraling part261binFIG. 3, a portion2613extending around the center9from the end2611to a position located anywhere from a half circle (angle θ1=90°) up to a full circle (angle θ1=180°) has a thickness d2, which is greater than a thickness h2of the portion2613after step (b) is performed. In other words, in the aforementioned Mode A, the portion2613is used as the specified portion, and the thickness d2of the portion2613is used as the dimension. The angle θ1is an angle formed around the center9by the direction92in which the spiral extends from the end2611.

By performing step (b) on the iron casting261obtained in step (a), the panel26ais obtained from the fixing part261a, and the compression member26bis obtained from the spiraling part261b.

According to this method for manufacturing an orbiting scroll, the dimensions d1, d2of the portions2612,2613of the end2611at the center9of the spiral in step (a) are made to be greater than the dimensions h1, h2of the portions2612,2613after step (b) is performed, thereby increasing the heat capacity of the end portions2612,2613where stress is readily concentrated. These portions2612,2613are consequently more resistant to cooling even after being formed. The hardness of the portions2612,2613can thereby be increased, and wear in the orbiting scroll26can thereby be reduced.

The portion2613after step (b) is performed encircles the hole41formed in the fixed scroll24when the orbiting scroll26is incorporated into the compression mechanism15, as shown inFIG. 3. InFIG. 3, the position of the hole41is shown by dashed lines. Stress readily concentrates in the compression member26bnear the hole41, but wear in the orbiting scroll26is reduced because the portion2613is high in hardness.

FIGS. 4 and 5schematically depict cross sections along the direction91of part of the fixing part261aand spiraling part261bof the iron casting261obtained in step (a). InFIGS. 4 and 5, the shape of the iron casting261, i.e., of the orbiting scroll26obtained by performing step (b) is shown by single-dashed lines.

In the spiraling part261binFIGS. 4 and 5, the thickness d3of the base portion261b1fixed to the fixing part261ais greater than the thickness h3of the portion261b1after step (b) is performed. Specifically, in the aforementioned Mode A, the base portion261b1is used as the specified portion, and the thickness d3of the base portion261b1is used as the dimension.

This shape of the spiraling part261bresults in increased heat capacity in the base portion261b1where stress readily concentrates. Consequently, the base portion261b1is resistant to cooling even after being formed. The hardness of the base portion261b1can thereby be increased, and thereby deformation in the spiraling part261bafter being machined can be prevented.

For example, in the portions2612,2613described above, the thickness d3of the base portion can be made greater than the thickness h3.

InFIGS. 4 and 5, the thickness d3of the base portion261b1decreases towards the distal end2614of the spiraling part261bwhen seen from the fixing part261a.

With this shape of the spiraling part261b, in cases in which the iron casting261is formed using a metal die in step (a), the iron casting261can be easily removed from the metal die to the opposite direction of the distal end2614. This is because friction between the metal die and the base portion261b1of the spiraling part261bis reduced.

InFIGS. 4 and 5, not only in the base portion261b1but the thickness d4of the portion261b2near the distal end2614is also greater than the thickness h4after step (b) is performed.

With this shape of the spiraling part261b, hardness can be increased not only in the base portion261b1, but in the portion261b2near the distal end2614as well.

With this shape of the spiraling part261b, since friction between the spiraling part261band the metal die is reduced, the iron casting261is readily removed from the metal die. Moreover, since the thickness d4of the portion261b2near the distal end2614is small, the amount cut away in step (b) is smaller than the base portion261b1, and thereby the iron casting261is readily machined.

Furthermore, inFIG. 5, the side surfaces261bsof the spiraling part261bare flat surfaces in both the base portion261b1and the portion261b2near the distal end2614. The side surfaces of the base portion261b1are inclined with respect to the side surfaces of the portion261b2near the distal end2614.

Specifically, the side surfaces of the base portion261b1are inclined at an angle θ3with respect to a plane261sperpendicular to the surface261asof the fixing part261a. The side surfaces of the portion261b2near the distal end2614are inclined at an angle θ4with respect to the plane261s. The angle θ3is greater than the angle θ4.

With this shape of the spiraling part261b, the side surfaces261bsof the spiraling part261bhave a tapered shape, and the iron casting261is therefore readily removed from the metal die.

Returning toFIG. 4, the spiraling part261bis greater in height d6from the fixing part261athan the height h6after step (b) is performed.

With this shape of the spiraling part261b, the hardness of the portion261b2near the distal end2614can also be increased. In the spiraling part261binFIG. 4, the thickness d3of the base portion261b1and the height d6of the spiraling part261bare both greater than the thickness h3and the height h6after step (b) is performed, but it is also acceptable if, e.g., only either one of these dimensions is greater than the dimension after step (b) is performed.

For example, just the height d6of the spiraling part261bcan be made greater than the height h6after step (b) is performed. In other words, in Mode A described above, the height d6of the spiraling part261bcan be used as the dimension.

InFIG. 4, all of the base portion261b1, the portion261b2near the distal end2614, and the portion261a1on the spiraling part261bside of the fixing part261aare cut. The thickness c1at which the base portion261b1is cut is greater than both the thicknesses c2, c3at which the portion261b2near the distal end2614and the portion261a1of the fixing part261aare cut.

In the iron casting261obtained in step (a) in this mode, the dimension of the base portion261b1of the spiraling part261bis designed to be greater than the dimensions of the portion261b2near the distal end2614and the portion261a1of the fixing part261a. Consequently, the heat capacity of the base portion261b1can be made greater than the heat capacity of the other portions261b2,261a1, and thereby the hardness of the base portion261b1can be made higher than the other portions261b2,261a1.

Second Embodiment

The present embodiment also relates to a method for manufacturing an orbiting scroll26as a scroll member. This manufacturing method comprises a step (a) and a step (b), similar to the first embodiment. The difference from the first embodiment is in the shape of the iron casting261obtained in step (a). The shape of the iron casting261is described hereinbelow usingFIGS. 6 and 7. InFIGS. 6 and 7, the shape of the iron casting261obtained by performing step (b) is shown by single-dashed lines.

In the fixing part261ainFIG. 6, the thickness d5of the portion261a2near the center9is greater than the thickness h5of the portion261a2after step (b) is performed.

With this method for manufacturing the orbiting scroll26, the heat capacity of the portion261a2of the fixing part261aincreases. Consequently, the portion261a2is resistant to cooling even after being formed, and thereby the portion2617in the spiraling part261bnear the center9is resistant to cooling. The hardness of the portion2617of the spiraling part261bcan thereby be increased, and wear in the orbiting scroll26can thereby be reduced.

InFIG. 6, the iron casting261further includes a protruding part261c. The protruding part261cis fixed to the fixing part261aon the side opposite the spiraling part261band extends in a cylindrical shape in the direction opposite the spiraling part261bfrom the edge of the portion261a2of the fixing part261a.

The protruding part261cmachined in step (b) is used as the bearing26c(FIG. 1), described hereinafter, in the orbiting scroll26.

InFIG. 7, the iron casting261further includes a protruding part261d. The protruding part261dis fixed near the center9of the fixing part261aon the side opposite the spiraling part261b.

In step (b), the protruding part261dis cut into a tube shape which opens only in the direction opposite the spiraling part261b.

With this method for manufacturing the orbiting scroll26, the protruding part261dis also formed in step (a), whereby the iron casting261is thicker near the center9. Consequently, the center9vicinity of the iron casting261is greater in heat capacity and more resistant to cooling even after being formed, and whereby the spiraling part261bis also more resistant to cooling in the portion2617near the center9. The hardness of the portion2617of the spiraling part261bcan thereby be increased, and wear in the orbiting scroll26can be reduced.

Moreover, the protruding part261dmachined in step (b) is used as the bearing26c(FIG. 1), described hereinafter, in the orbiting scroll.

Third Embodiment

The method for manufacturing a fixed scroll24as a scroll member comprises a step (a) and a step (b), similar to the first embodiment.

FIGS. 8 and 9schematically depict an iron casting241obtained in step (a) in the manufacture of the fixed scroll24. The iron casting241has a fixing part241aand a spiraling part241b. The spiraling part241bis fixed to the fixing part241aand extends in a spiraling formation. InFIGS. 8 and 9, the shape of the spiraling part241bobtained by performing step (b) is shown by single-dashed lines.

In the iron casting241obtained in step (a), the dimension of the specified portion of the spiraling part241bis greater than the dimension of the same portion after step (b) is performed (Mode B), similar to the iron casting261shown inFIGS. 2 and 3.

Specifically, inFIG. 8, only in a portion2412of an end2411at the center9of the spiral, the thickness d11is greater than the thickness h11of the portion2412after step (b) is performed. Specifically, in the aforementioned Mode B, the portion2412is used as the specified portion, and the thickness d11of the portion2412is used as the dimension.

In the spiraling part241binFIG. 9, a portion2413extending around the center9from the end2411up to a position located anywhere from a half circle (angle θ2=90°) to a full circle (angle θ2=180°) has a thickness d12greater than a thickness h12of the portion2413after step (b) is performed. Specifically, in the aforementioned Mode B, the portion2413is used as the specified portion, and the thickness d12of the portion2413is used as the dimension. Herein, the angle θ2is the angle formed by the direction92in which the spiral extends from the end2411around the center9.

By performing step (b) on the iron casting241obtained in step (a), a panel24ais obtained from the fixing part241a, and a compression member24bis obtained from the spiraling part241b.

With this method for manufacturing the fixed scroll24, heat capacity is greater in the portions2412,2413of the ends where stress readily concentrates, and the hardness of the portions2612,2613can be increased, similar to the method for manufacturing the orbiting scroll26described in the first embodiment. Consequently, wear in the fixed scroll24can be reduced.

The portion2413after step (b) is performed encircles a hole41, as shown inFIG. 9. Stress readily concentrates in the compression member24bnear the hole41, but since the portion2413has high hardness, wear in the fixed scroll24is reduced.

Also in the method for manufacturing the fixed scroll24, the shape shown inFIGS. 4 and 5is used in the spiraling part241b, whereby the same effects as those described in the first embodiment are obtained.

In the fixing part241a, the thickness of the portion near the center9in the fixing part241ais increased, similar to the second embodiment, whereby hardness can be increased in the portion of the spiraling part241bnear the center9.

Fourth Embodiment

An orbiting scroll26manufactured by either one of the methods in the first and second embodiments will be described.

FIG. 10uses a graph to show the relationship between distance from the center9and hardness of the base portion in a compression member26bof the orbiting scroll26obtained by performing step (b). InFIG. 10, the position of the outside edge of the bearing26c(FIG. 1) is shown by a single-dashed line.

According to the graph shown inFIG. 10, using the manufacturing methods of the first and second embodiments makes it possible to increase the hardness of the base portion of the compression member26bto HRB 95 or greater near the center9, i.e., farther inward than the outside edges of the bearing26c.

Consequently, in the vicinity of the center9, the compression member26bdoes not readily deform even if the ratio H/T of the height H of the compression member26bfrom the panel26a(FIGS. 4 and 5) with respect to the thickness T of the compression member26b(FIGS. 4 and 5) equals to or exceeds 8.5. The orbiting scroll26can be reduced in size if the orbiting scroll26is designed using the ratio H/T.

Wear and deformation do not readily occur in the orbiting scroll26manufactured by the methods according to the first and second embodiments. Consequently, failure of the compression mechanism15can be reduced by using the orbiting scroll26as a scroll member of the compression mechanism15.

Also in the fixed scroll24manufactured using the method according to the third embodiment, a compression member24bhaving a degree of hardness similar to that of the orbiting scroll26is obtained. Consequently, the ratio H/T of the height H of the compression member24bto the thickness T can be 8.5 or greater.

Moreover, the fixed scroll24is not likely to undergo wear or deformation. Consequently, failure of the compression mechanism15can be reduced by using the fixed scroll24as a scroll member of the compression mechanism15.

Working Examples

The structure of the scroll compressor1will be described in greater detail usingFIG. 1. In addition to the case11and the compression mechanism15, the scroll compressor1comprises an Oldham ring2, a fixing member12, a motor16, a crankshaft17, a suction pipe19, a discharge pipe20, and a bearing60.

The case11has a cylindrical shape and extends along the direction91. The Oldham ring2, the fixing member12, the motor16, the crankshaft17, and the bearing60are housed within the case11.

The motor16has a stator51and a rotor52. The stator51is annular in shape and is fixed to an internal wall11aof the case11. The rotor52is provided to the inner periphery side of the stator51and is made to face the stator51with an air gap.

The crankshaft17extends along the direction91and has a main shaft17aand an eccentric part17b. The main shaft17ais a portion that rotates around a rotational axis90and is connected to the rotor52. The eccentric part17bis a portion disposed with being eccentric from the rotational axis90, and is connected to the upper side of the main shaft17a. The lower end of the crankshaft17is slidably supported by the bearing60.

The fixed member12is specifically a housing inFIG. 1, and is fitted without any gaps into the internal wall11aof the case11. The fixed member12is fitted into the internal wall11aby, e.g., press fitting, shrink fitting, or another method. The fixed member12may be fitted into the internal wall11avia a seal.

Since the fixed member12is fitted into the internal wall11awithout gaps, a space28positioned on the underside of the fixed member12and a space29positioned on the top side are partitioned without any gaps. Consequently, the fixed member12is capable of maintaining pressure differences that occur between the space28and the space29. The pressure in the space28is high, and the pressure in the space29is low.

A hollow31opened in the top side of the fixed member12is provided in the vicinity of the rotational axis90. The eccentric part17bof the crankshaft17is accommodated within the hollow31. Furthermore, the fixed member12has a bearing32and a hole33. The bearing32supports the main shaft17awhile the main shaft17aof the crankshaft17is in a state of being inserted through the hole33.

The surface on the top side of the fixed scroll24has a concavity. A space45enclosed by a portion42in this surface having the concavity is closed by a lid44. The lid44partitions two spaces of different pressures; i.e., the space45and the space29on the top side.

The orbiting scroll26further comprises a bearing26c. The bearing26cis linked to the underside of the panel26a, and the bearing26cslidably supports the eccentric part17bof the crankshaft17.

The flow of refrigerant through the scroll compressor1will be described usingFIG. 1. InFIG. 1, the flow of refrigerant is depicted by arrows. Refrigerant is sucked in through the suction pipe19and is led into the compression chamber (space40) of the compression mechanism15. The refrigerant compressed by the compression chamber (space40) is discharged out to the space45through a discharge hole41provided near the center of the fixed scroll24. Consequently, the pressure in the space45is high. Conversely, the pressure in the space29partitioned from the space45by the lid44remains low.

The refrigerant in the space45flows sequentially through a hole46provided in the fixed scroll24and a hole48provided in the fixed member12in this order, and then flows into the space28below the fixed member12. The refrigerant in the space28is directed into a gap55by a guiding plate58. The gap55is herein provided between the case11and part of the side surface of the stator51.

The refrigerant that has flowed through the gap55to the space below the motor16then flows through an air gap or a gap56in the motor16, and then flows into the discharge pipe20. The gap56is herein provided between the case11and another part of the side surface of the stator51.

INDUSTRIAL APPLICABILITY

The present invention can be widely applied to the field of scroll members and their manufacturing methods.