Scroll type fluid machine

Abstract: Object: To provide a scroll type fluid machine in which a pair of mutually engaged scrolls, one being made of an aluminum material, the other being made hard, are provided, a wearing amount of the engaging tip seal and end plate is reduced, and yet the growth of wearing of both elements is equalized. Construction: Tip seals (47, 48) provided at the tips of wraps (12, 16) of a pair of scrolls (10, 14) are made of a composite plastic material composed of a polyphenylene sulfide as a base material and a carbon fiber and others as a filler, the carbon fiber composition rate of the tip seal material of the scroll (10) made of an aluminum material is made higher than the carbon fiber composition rate of the tip seal material of the other scroll (14) made of an aluminum material applied by a surface treatment or of a ferrous metal or of a ferrous metal applied by a surface treatment, thereby the wearing amount of each engaging tip seal (47, 48) and end plate (11, 15) is reduced and simultaneously the growth of wearing of both elements is equalized.

Description: BACKGROUND OF THE INVENTION: Field of the Invention: The present invention relates to a scroll type fluid machine used, for example, as a component in a refrigeration cycle etc. Description of the Prior Art: In recent days, for an air conditioning unit, a compressor named a scroll type compressor (a scroll type fluid machine) in which a pair of mutually engaged spiral wraps are provided, is used for a reason that an operation of high efficiency can be obtained. In Fig. 4, an example of a heretofore known scroll type compressor as described in Japanese Laid-open application No. 5-240174 is shown, and this scroll type compressor is now described. In Fig. 4, numeral 1 designates a hermetic housing. This hermetic housing 1 consists of a cup-like body 2, a front end plate 4 fixed thereto by bolts 3 and a cylindrical element 6 fixed thereto by bolts 5. And a rotating shaft 7, passing through said cylindrical element 6, is supported rotatably by the housing 1 via a bearing 8 and a bearing 9. Within the hermetic housing 1, a stationary scroll 10 (one of said pair of scroll elements) and a swivel scroll 14 engaged therewith (the other of said pair of scroll elements) are provided. More particularly, the stationary scroll 10 has an end plate 11 and a spiral wrap 12 provided standingly on its inner surface. Said end plate 11 is fixed to the bottom side of the cup-like body 2 by bolts 13. The outer circumferential surface of the end plate 11 and the inner circumferential surface of the cup-like body 2 are sealingly contacted each other, thereby the inner space of the housing 1 is partitioned so that, in a space within the hermetic housing 1, a discharge cavity 31 is formed on the outer side of the end plate 11 and a suction chamber 28 is formed on the inner side of the end plate 11. Incidentally, at the central part of the end plate 11, a discharge port 29 is provided so as to be opened and closed by a discharge valve 30. The swivel scroll 14 has an end plate 15 and a spiral wrap 16 provided standingly on its inner surface, said spiral wrap 16 being of a substantially same shape as the spiral wrap 12 of the stationary scroll 10. The swivel scroll 14 and the stationary scroll 10 are mutually engaged eccentrically by a length of a radius of the revolution with a deviation of angle of 180 degrees, as shown in the figure. On a tip surface of each spiral wrap 12, 16, a spiral tip seal 17, 18 is provided ridgedly along the spiral. More particularly as to the fitting of the tip seal 17, a groove 17a is formed along the spiral on the tip surface of the spiral wrap 12, and the spiral tip seal 17 is inserted in the groove 17a so that a portion of one side of the tip seal 17 is projecting from the tip surface of the spiral wrap 12. Likewise as to the fitting of the tip seal 18, a groove 18a is formed along the spiral on the tip surface of the spiral wrap 16 and the spiral tip seal 18 is inserted in the groove 18a so that a portion of one side of the tip seal 18 is projecting from the tip surface of the spiral wrap 16. The tip seal 17 of the spiral wrap 12 contacts sealingly to the inner surface of the end plate 15 of the opponent swivel scroll 14, and the tip seal 18 of the spiral wrap 16 contacts sealingly to the inner surface of the end plate 11 of the opponent stationary scroll 10. The side surfaces of the spiral wrap 12 and of the spiral wrap 16 make line contacts at a plurality of places and thereby form a plurality of crescent compression chambers 19a, 19b (fluid chambers) at the positions between the wraps which make nearly a point symmetry each other around the centers of the spirals. Within a cylindrical boss 20 provided projectingly at the central part of the outer surface of the end plate 15, a drive bush 21 is inserted rotatably via a revolutional bearing 23, and within a slide groove 24 provided in said drive bush 21, an eccentric drive pin 25 provided eccentrically and projectingly at the inner end of the rotating shaft 7 is inserted slidably. Said drive bush 21 is fitted with a balance weight 27 for balancing dynamic unbalances caused by revolutional swivel motions of the swivel scroll 14. Incidentally, in Fig. 4, numeral 36 designates a thrust bearing provided between the circumferential edge of the outer surface of the end plate 15 and the inner surface of the front end plate 4, numeral 26 designates a rotation preventing mechanism consisting of an Oldham coupling for allowing revolutional swivel motions of the swivel scroll 14 but preventing a rotation thereof, and numeral 37 designates a balance weight fixed to the rotating shaft 7. In a scroll type compressor so constructed, upon the rotating shaft 7 being driven, the swivel scroll 14 is driven via a revolutional drive mechanism consisting of the eccentric drive pin 25, the drive bush 21, the cylindrical boss 20, etc. Thereupon, the swivel scroll 14, being prevented from rotating by the rotation preventing mechanism 26, makes revolutional swivel motions on a circular track having a radius of the revolution, i.e. a radius which is an eccentricity amount between the rotating shaft 7 and the eccentric drive pin 25. Then, the line contact parts of the side surfaces of the spiral wrap 12 and of the spiral wrap 16 move gradually to the direction of the spiral centers, and as a result, the compression chambers 19a, 19b move, with volume thereof being reduced, to the direction of the spiral centers. Accompanying with such movement of the compression chambers 19a, 19b, a gas (fluid) flown into a suction chamber 28 through a suction inlet (not shown in the figure) is taken into each of the compression chambers 19a, 19b from openings of the outer finish ends of the spiral wraps 12, 16 and, while being compressed, comes in the central chamber 22, and upon completion of compression, passing through the discharge port 29 and pushingly opening the discharge valve 30, the gas is discharged into the discharge cavity 31 and flown out through a discharge outlet (not shown in the figure). Incidentally, the movement occurring at the swivel scroll 14 while it is making revolutional swivel motions, is allowed by the slide groove 24, i.e. while the swivel scroll 14 is making revolutional swivel motions, it receives a centrifugal force acting to the direction of the eccentricity and a gas pressure by the compressed gas in each of the compression chambers 19a, 19b and is pushed to the direction to increase the revolutional radius. With such motions, the side surfaces of the spiral wrap 16 of the swivel scroll 14 contact sealingly to the side surfaces of the spiral wrap 12 of the stationary scroll 10, by which leakage of the gas from the compression chambers 19a, 19b is prevented. And the motions of the swivel scroll 14 of which revolutional radius is about to change when the side surface of the spiral wrap 12 and the side surface of the spiral wrap 16 are making sliding motions each other while they are keeping sealing contacts, are allowed by the eccentric drive pin 25 which makes slide movements within the slide groove 24 along its longitudinal direction. In a scroll type compressor, a weight reduction both of the stationary scroll 10 and the swivel scroll 14 is being pursued. For this purpose, in the prior art, the stationary scroll 10 and the swivel scroll 14 are made of an aluminum material, and the spiral wraps 12, 16 of both scrolls 10, 14 so made of an aluminum material and the tip seals 17, 18 made of a composite plastic material, as has so far been used, composed of a polyphenylene sulfide (PPS) as a base material and a carbon fiber of 15 weight percent and others as a filler, are used in combination. However, the stationary scroll 10 and the swivel scroll 14 made of an aluminum material, if used, have such a disadvantage that an extreme wearing occurs or a seizure occurs, etc. Therefore, it is disclosed that one of the scrolls is applied by a hard surface treatment, more concretely as shown in Fig. 5, one of the scrolls, for example, the movable swivel scroll 14, is applied on the surface by a surface treatment, such as an alumite (aluminum is anodized and aluminum oxide coating is formed on the surface), a special alumite (aluminum is anodized, aluminum oxide coating is formed on the surface and a fluororesin etc. is impregnated on the surface), etc. However, while a hard aluminum oxide coating is formed by this surface treatment on the inner surface of the end plate 15 of the swivel scroll 14, a surface roughness becomes worse than that of the aluminum material. For this reason, upon the swivel scroll 14 being driven, the tip seal 17 of the stationary scroll 10 making sealing contacts to the inner surface (the surface being made hard and the surface roughness being worsened by a surface treatment) of the end plate 15 of the swivel scroll 14, and the tip seal 18 of the swivel scroll 14 making sealing contacts to the inner surface (soft surface of aluminum material itself) of the end plate 11 of the stationary scroll 10, make relative sliding motions between the respective components, and a slide wearing occurs between the relative two surfaces. More concretely, at the portion where the tip seal 17 of the stationary scroll 10 made of a composite plastic material (composed of a polyphenylene sulfide as a base material and a carbon fiber of 15 weight percent and others as a filler) and the end plate 15 of the swivel scroll 14 applied by a surface treatment make sealing contacts (combination of a composite plastics and a treated surface), there occurs a considerable slide wearing on the side of the tip seal 17, and likewise at the portion where the tip seal 18 of the swivel scroll 14 and the end plate 11 of the stationary scroll 10 made of an aluminum material make sealing contacts (combination of a composite plastics and an aluminum material), there occurs a considerable wearing on the side of the end plate 11. And yet generally, a slide wearing grows quickly as the contact pressure becomes larger. Therefore, if a compressor is operated in a state named a high differential pressure operation where a differential pressure of a discharge pressure and a suction pressure is large, and as a contact pressure between the tips of tip seals 17, 18 and the inner surfaces of the end plates 11, 15 becomes larger, the wearing of one component grows quickly, i.e. the wearing of the tip seal 17 of the stationary scroll 10 and the wearing of the inner surface of the end plate 11 of the stationary scroll 10 grow more quickly than those of the engaging swivel scroll 14, which leads to a problem that a life of product is hurt. SUMMARY OF THE INVENTION: In view of the above-described problems inherent in the prior art, it is an object of the present invention to provide a scroll type fluid machine in which a pair of mutually engaged scroll elements, one being made of an aluminum material, the other being applied by a hard treatment, are provided and, while the wearing amount of each engaging tip seal and end plate can be reduced, the degree of growth of wearing of both components can be equalized. For attaining the above object, the present invention set out in Claim 1 discloses that spiral tip seals provided at the tip surfaces of spiral wraps of a pair of scroll elements are made of a composite plastic material composed of a polyphenylene sulfide as a base material and a carbon fiber and others as a filler and yet the carbon fiber composition rate of a tip seal material of a scroll element made of an aluminum material is made higher than the carbon fiber composition rate of a tip seal material of the other scroll element made of an aluminum material applied by a surface treatment or of a ferrous metal or of a ferrous metal applied by a surface treatment. The present invention set out in Claim 2 discloses, in order to obtain an excellent effect of reducing the wearing amount in addition to the object mentioned above, that the carbon fiber composition rate, as mentioned in Claim 1, is specified in the range of 17 to 50 weight percent with respect to a tip seal material of a scroll element made of an aluminum material and in the range of 3 to 12 weight percent with respect to a tip seal material of the other scroll element. The present invention set out in Claim 3 discloses, in order to obtain an excellent effect of reducing the wearing amount to meet a character of a tip seal material in addition to the object mentioned above, that the other scroll element mentioned in Claim 1 is applied by a hard coating treatment on the surface. The present invention set out in Claim 4 discloses, in order to obtain a further excellent effect of reducing the wearing amount to meet a character of a tip seal material, that the surface treatment set out in Claim 3 is made by an alumite treatment or a special alumite treatment. According to the present invention set out in Claim 1, a tip seal fitted to a scroll element made of an aluminum material is made of a composite plastic material of a high carbon fiber composition rate and has an increased hardness and an enhanced wear resistance. On the contrary, a tip seal fitted to the other scroll element which is engaged with a scroll element made of an aluminum material and is made hard by a surface treatment etc., is made of a composite plastic material of a lowered carbon fiber composition rate and has a lowered hardness. As a result of the former, the tip seal of the scroll element made of an aluminum material is reduced of the wearing amount to be otherwise caused by the worsened surface roughness and the hard surface of the opponent inner surface of the end plate of the other scroll applied by a surface treatment etc. And as a result of the latter, the end plate of the scroll element made of an aluminum material is reduced of the wearing amount of the inner surface to be otherwise caused by the sliding contact with the opponent tip seal. Thereby, the wearing amount of each engaging tip seal and end plate is reduced and simultaneously the degree of growth of wearing of both components is induced to be equalized. By the above, a life of product is no longer hurt and a reliability of product is enhanced. According to the present invention set out in Claim 2, a good effect of reducing the wearing amount is secured. According to the present invention set out in Claim 3, an effect of reducing the wearing amount to meet a character of a tip seal material is obtained. According to the present invention set out in Claim 4, a further effect of reducing the wearing amount to meet a character of a tip seal material is obtained. BRIEF DESCRIPTION OF THE DRAWINGS: In the accompanying drawings: Fig. 1 is a cross section showing a scroll type compressor of a preferred embodiment according to the present invention. Fig. 2 is a table showing compositions of materials of tip seals fitted to a stationary scroll and a swivel scroll of said compressor of a preferred embodiment, together with materials of a scroll engaged therewith. Fig. 3 is a graph showing, in comparison, wearing amounts of a tip seal of a stationary scroll and of an inner surface of an end plate of a stationary scroll, in the high differential operation tests, of a compressor using tip seals of changed carbon fiber composition rates and of a compressor using tip seals of same composition as heretofore used. Fig. 4 is a cross section for explaining a construction of a scroll type compressor of the prior art. Fig. 5 is a table showing compositions of materials of tip seals fitted to said scroll type compressor of the prior art, together with materials of a scroll engaged therewith. DESCRIPTION OF THE PREFERRED EMBODIMENTS: In the below, the present invention is described based on a preferred embodiment as shown in Fig. 1 to Fig. 3. Incidentally, in this preferred embodiment, component parts same as those mentioned in the above description are given same reference numerals and further explanation thereof will be omitted, and different elements (features of the invention) are described in this article. A scroll type compressor according to the present invention differs from the prior art in using tip seals 17, 18 made of a composite plastic material of a different composition. For a purpose of distinction from tip seals 17, 18 of the prior art, a tip seal fitted to the stationary scroll 10 is designated by numeral 47 and a tip seal fitted to the swivel scroll 14 is designated by numeral 48. According to the present invention, the carbon fiber composition rate of the tip seal material of a scroll element made of an aluminum material, i.e. the carbon fiber composition rate of the material of the tip seal 47 fitted to the stationary scroll 10, is made higher than the carbon fiber composition rate of of the tip seal material of the other hard scroll element, i.e. the carbon fiber composition rate of the material of the tip seal 48 fitted to the swivel scroll 14. More concretely, while the tip seal 17 of the conventional stationary scroll 10 and the tip seal 18 of the conventional swivel scroll 14, as described previously, are both made of a composite plastic material of a same composition composed of a poly.phenylene sulfide (PPS) as a base material and a carbon fiber of 15 weight percent and others as a filler, as shown in Fig. 5, the tip seal 47 of the stationary scroll 10 and the tip seal 48 of the swivel scroll 14 of this preferred embodiment are different in the material composition, e.g. as shown in Fig. 2, the tip seal material of the stationary scroll 10 made of an aluminum material has a higher carbon fiber composition rate of 20 weight percent, and the tip seal material of the swivel scroll 14 applied by a surface treatment on an aluminum material has a lower carbon fiber composition rate of 10 weight percent. Incidentally, the swivel scroll 14 is applied on the surface of an aluminum material by an alumite treatment (aluminum is anodized and aluminum oxide coating is formed on the surface) or by a special alumite treatment (aluminum is anodized, aluminum oxide coating is formed on the surface and a fluororesin etc. is impregnated on the surface) (surface treatment and hard coating treatment), thus a hard coating is formed on the surface of the swivel scroll 14 made of an aluminum material. By so changing the carbon fiber composition rate, the wearing of the tip seal 47 of the stationary scroll 10 and of the inner surface of the end plate of the stationary scroll 10 can be reduced, and yet the wearing amount of said tip seal 47 and of the inner surface of the end plate can be equalized. These effects are confirmed by experiments. In the experiments, a scroll type compressor of the prior art in which tip seals 17, 18 made of a composite plastic material of same composition (composed of a polyphenylene as a base material and a carbon fiber of 15 weight percent and others as a filler) are incorporated, and a scroll type compressor of this preferred embodiment according to the present invention in which tip seals 47, 48 of which material composition is different between the stationary scroll 10 and the swivel scroll 14 are incorporated, are operated in a high differential pressure operation (compression operation with a large differential pressure between the discharge pressure and the suction pressure), and the wearing amounts of the tip seals 17, 47 of each compressor and of the inner surface of the stationary scroll 10 of each compressor, after passing of a certain operation time, are measured. The result of the experiments is shown in Fig. 3. From Fig. 3, it is found that, by changing the carbon fiber composition rate, in comparison with the wearing amounts of the tip seal 17 of the stationary scroll 10 and of the inner surface of the end plate of the stationary scroll 10, both in a conventional scroll type compressor, the wearing amounts of the tip seal 47 of the stationary scroll 10 and of the inner surface of the stationary scroll 10, both in this preferred embodiment according to the present invention, are far smaller and yet the growth of wearing of both components is nearly a same degree. According to the experiments, not limited to the above-described carbon fiber composition rate, in the range of the carbon fiber composition rate of the material of the tip seal 47 fitted to the stationary scroll 10 of 17 to 50 weight percent, and in the range of the carbon fiber composition rate of the material of the tip seal 48 fitted to the swivel scroll 14 of 3 to 12 weight percent, a same excellent effect of reducing the wearing amount can be obtained. Such reduction of the wearing amount of the tip seal 47, i.e. the reduction of the wearing amount of the tip seal 47 to be otherwise caused by the worsened surface roughness and the hard surface of the opponent inner surface of the end plate of the swivel scroll 14 applied by a surface treatment, is brought presumably by an increased hardness and an enhanced wear resistance of the tip seal material with its carbon fiber composition rate being enhanced. The reduction of the wearing amount of the inner surface of the end plate of the stationary scroll 10, i.e. the reduction of the wearing amount of the inner surface of the end plate to be otherwise caused by the sliding contacts with the tip seal 48, is brought presumably by a lowered hardness of the material of the tip seal 48 with its carbon fiber composition rate being lowered. Such reduction of the wearing amount acts presumably to induce the growth of wearing between each engaging tip seal 47, 48 and end plate 11, 15 of each scroll 10, 14 to be equalized. If a swivel scroll 14 applied by a hard coating treatment on the surface is employed, an excellent effect of reducing the wearing amount to meet a character of a tip seal material can be brought. Especially, if this treatment is an alumite treatment (aluminum is anodized and aluminum oxide coating is formed on the surface) or a special alumite treatment (aluminum is anodized, aluminum oxide coating is formed on the surface and a fluororesin etc. is impregnated on the surface), a further effect of reducing the wearing amount to meet a character of a tip seal material can be obtained. Needless to mention, the swivel scroll 14 is not limited to that made of an aluminum material applied by a surface treatment, but that made hard of a ferrous metal or of a ferrous metal applied by a surface treatment gives the same effect. Incidentally, the preferred embodiment is described with an example of a pair of mutually engaged scrolls in which a stationary scroll 10 is made of an aluminum material but, not limited thereto, if a swivel scroll 14 is made of an aluminum material and a stationary scroll 10 is made of an aluminum material with a surface treatment or made of a ferrous metal or made of a ferrous metal applied by a surface treatment, the same effect is obtained. Further, needless to mention, the present invention is applied to a scroll type compressor but, not limited thereto, it can be applied to other scroll type fluid machines. According to the present invention set out in Claim 1, as described above, the wearing amount between each engaging tip seal and end plate, which has so far been a problem in a pair of mutually engaged scroll elements, one being made of an aluminum material and the other being applied by a hard treatment, can be reduced. And yet, the growth of wearing both of engaging tip seal and inner surface of end plate can be equalized, thus a disadvantage of the prior art where the wearing of one scroll grows quicker can be supressed. As a result, a life of product is no longer uselessly hurt and a reliability of product can be increased. According to the present invention set out in Claim 2, an excellent effect of reducing the wearing amount can be obtained in addition to the effect of the invention set out in Claim 1. According to the present invention set out in Claim 3, an excellent effect of reducing the wearing amount can be brought to meet a character of a tip seal material, in addition to the effect of the invention set out in Claim 1. According to the present invention set out in Claim 4, a further excellent effect of reducing the wearing amount can be obtained to meet a character of a tip seal material, in addition to the effect of the invention set out in Claim 1. While the preferred form of the present invention has been described, variations thereto will occur to those skilled in the art within the scope of the present inventive concepts which are delineated by the following claims.

Claims: A scroll type fluid machine in which a pair of scroll elements (10,14), each having a spiral wrap (12,16) provided standingly on one surface of a respective end plate thereof, one of said scroll elements (10,14) being made of an aluminum material, the other being made of an aluminum material applied by a surface treatment or of a ferrous metal or of a ferrous metal applied by a surface treatment, are engaged with a deviation of phase of 180 degrees so as to form fluid chambers (19a,19b) therebetween; and a spiral tip seal (47,48) is provided in a groove formed along the spiral at a tip surface of the respective spiral wrap (12,16) of said pair of scroll elements (10,14); characterized in that said tip seal (47,48) is made of a composite plastic material composed of a polyphenylene sulfide as a base material and a carbon fiber and others as a filler; and the carbon fiber composition rate of the tip seal material of said scroll element (10,14) made of aluminum material is made higher than the carbon fiber composition rate of the tip seal material of the other scroll element. A scroll type fluid machine as claimed in claim 1, characterized in that the carbon fiber composition rate of the tip seal material of said scroll element (10,14) made of aluminum material is 17 to 50 weight percent and the carbon fiber composition rate of the tip seal material of the other scroll element (10,14) is 3 to 12 weight percent. A scroll type fluid machine as claimed in claim 1 or 2, characterized in that a hard coating treatment is applied on the surface of said the other scroll element (10,14). A scroll type fluid machine as claimed in claim 3, characterized in that the surface treatment of said the other scroll element (10,14) made of aluminum material is an alumite treatment or a special alumite treatment.

Inventors: HIROOKA KATSUMI, KOBAYASHI HIROYUKI, MATSUDA SUSUMU, HIROOKA, KATSUMI, KOBAYASHI, HIROYUKI, MATSUDA, SUSUMU, Hirooka, Katsumi, c/o Mitsubishi Jukyogo K.K., Kobayashi, Hiroyuki, c/o Nagoya R&amp;D C., Mitsubishi, Matsuda, Susumu, c/o Nagoya R&amp;D Ctr., Mitsubishi
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1995
Main classification: F04C18
IPC codes: F04C18, F04C27