Scroll type fluid machine

Abstract: Object: To provide a scroll type fluid machine which can suppress increase of inclining vibrations of an Oldham ring with facilitated adjustments. Construction: A stationary scroll (1) and a swivel scroll (2), in a pair, are engaged with each other and said swivel scroll (2) is driven to make revolutional motions, while prevented from making rotations, via an Oldham ring (18) disposed between an end plate (6) of said swivel scroll (2) and a frame (10) and, where a distance between said end plate (6) of the swivel scroll (2) and said frame (10) is s and a thickness of a ring portion (19) of said Oldham ring (18) is t, a gap δ, formed as (s-t), to a radius r of said ring portion (19) of the Oldham ring (18) is set so that δ/r is 0.01 or less. Thus, only by the ring portion (19) of the Oldham ring (18) being adjusted of its thickness, increase of inclining vibrations of an Oldham ring (18) can be suppressed.

Description: BACKGROUND OF THE INVENTION: Field of the Invention: The present invention relates to an improvement in a scroll type fluid machine to be used e.g. as a compressor, an expander, etc. Description of the Prior Art: Scroll type fluid machines, as having ability to operate with a high efficiency and a low noise, are used in a large number as compressors for air conditioning and refrigeration purposes. Generally, such a scroll type fluid machine e.g. a scroll type compressor has a compression portion 3, as shown in Fig. 4, in which a stationary scroll 1 and a swivel scroll 2, in a pair, are engaged with each other. More concretely, the stationary scroll 1 has an end plate 4 and a spiral wrap 5 provided projectingly from the inner face of the end plate 4. The swivel scroll 2 has likewise an end plate 6 and a spiral wrap 7 provided projectingly from the inner face of the end plate 6 and these wraps are engaged with each other with a predetermined phase. The stationary scroll 1 is fixed to a frame 10 provided e.g. within a hermetic casing 9, and the swivel scroll 2, with the back face of its end plate 6 being directed downwardly, is supported on the frame 10 via a thrust bearing 11. The central portion of the back face of the swivel scroll 2 is connected to a drive source, such as a rotational shaft 13 of an electric motor 12, provided within the hermetic casing 9 so that the swivel scroll in its entirety is driven to make revolutional swivel motions around the central axis of the stationary scroll 1. More concretely, at the shaft end of the rotational shaft 13, there is provided an eccentric pin 14 to be fitted rotatably in the central portion of the end plate of the swivel scroll 2, and by the rotation of the electric motor 12, the swivel scroll 2 is driven to make revolutional swivel motions relatively to the stationary scroll 1. The scroll type compressor makes compression work by the swivel scroll being driven by the electric motor 12 to make swivel motions, that is, a plurality of compression chambers 15 formed between the wraps make motions to reduce their volumes gradually while moving from a suction port 16 disposed on the outer side of the wrap 5 to a discharge port 17 disposed at the center of said wrap 5. In such scroll type fluid machine, in order to attain its work, there is provided an Oldham ring 18 between the end plate 6 of the swivel scroll 2 and the frame 10, as shown in Fig. 5, for prohibiting rotations of the swivel scroll 2. Said Oldham ring 18 is conventionally so constructed that it has a ring portion 19, as shown in Fig. 6, to be located between the end plate 6 of the swivel scroll 2 and the frame 10, and at two places where a diametrical line of the ring crosses the ring portion 19, two swivel side keys 20, 20 are formed, in a pair, projectingly from the end faces of the ring portion 19 as an integral body with the ring portion 19 and at two places of the ring portion 19 on a diametrical line rectangularly crossing said diametrical line, two stationary side keys 21, 21 are formed, in a pair, projectingly from the opposite end faces of the ring portion 19 as an integral body with the ring portion 19. The swivel side keys 20, 20 are fitted slidably in key ways 22 formed extendingly in the diametrical direction on the back face (lower face) of the end plate 6 of the swivel scroll 2 and the stationary side keys 21, 21 are likewise fitted slidably in key ways 23 formed extendingly in the diametrical direction on the upper face of the frame 10. Thus, upon rotation of the rotational shaft 13, the swivel side keys 20, 20 make reciprocal displacements in the direction of A (Fig. 6) within the key ways 22, the stationary side keys 21, 21 make reciprocal displacements in the direction of B (Fig. 6) within the key ways 23, thus the swivel scroll 2 makes revolutional swivel motions, without making rotational motions, around the central axis of the stationary scroll 1. In the Oldham ring 18, as the position of the key is deviated from the ring portion 19 in the thickness direction, if the scroll type fluid machine makes a high speed rotation, the Oldham ring 18 tends to incline by a moment caused by an inertia force Fi (Fig. 7) of the Oldham ring 18 and a reaction force Fd (Fig. 7) acting against said inertia force on the end face of the key way 22 of the swivel side. The Oldham ring 18 thus makes reciprocal movements while it is inclining and making vibrations (hereinafter such vibrations are referred to as "inclining vibrations). But at the time of a high speed rotation, as the inertia force Fi of the Oldham ring 18 increases in proportion to the square of the rotation, said moment sharply increases and the Oldham ring 18 makes more increased inclining vibrations. As a result, the Oldham ring 18 makes collisions with the end plate 6 of the swivel scroll 2 and with the flame 10, which causes shock sounds, thus there is a problem that the operation noises of the scroll type fluid machine are more and more increased. Especially, if the flatness of the Oldham ring 18 is not good enough, due to the revolutional swivel motions, being accompanied by conical motions, of the swivel scroll 2 in the compression process, vibrations of the Oldham ring 18 are remarkably increased and intensified, the Oldham ring 18 abnormally wears off, seizure occurs between the Oldham ring 18 and the end plate 6 (the swivel scroll 2) or between the Oldham ring 18 and the frame 10, and there is a fear of a fluid machine inoperability occurring. As a countermeasure therefor in recent years, there is such art as disclosed in the Japanese laid-open utility model application No. Hei 1(1989)-157201, that is, an allowable inclination of the Oldham ring 18 is restricted by the thickness of the swivel side key 20 and the depth of the key way 22 in which said swivel side key 20 is fitted, or as disclosed in the Japanese laid-open utility model application No. Hei 2(1990)-127701, that is, an allowable inclination of the Oldham ring 18 is restricted by the bottom face of the key way 23 in which the stationary side key 21 is fitted and the sliding face of the thrust bearing 11 with which said stationary side key 21 makes a sliding contact. In such art to make adjustment by the thickness of the individual separate key portions or to make control by the flatness between the separate key portions, only the individual portion of the key portions or between the key portions is restricted and there is a difficulty in making the thickness adjustment and the flatness control as a whole. Therefore, a facilitated countermeasure is being desired. A prior art scroll type fluid machine with the features of the preamble portion of the claim is described in EP 157 390 A. In this machine various gaps between an upper frame, an Oldhams coupling and an orbiting scroll are made as small as possible, typically an the order of 0.1 mm. SUMMARY OF THE INVENTION: In view of the circumstances as mentioned above, it is an object of the present invention to provide a scroll type fluid machine in which increase of the inclining vibrations can be suppressed by a facilitated adjustment. In order to attain said object, in the invention claimed in the Claim, where the distance between the end plate of the swivel scroll and the frame is s and the thickness of the ring portion of the Oldham ring is t, a gap δ, formed as (s-t), to the radius r of the ring portion of the Oldham ring is set so that δ/r is 0.01 or less. In the invention, in addition to the object mentioned above, in order to suppress increase of the inclining vibrations caused for reason of flatness also, warp of the ring portion of the Oldham ring located between the end plate of the swivel scroll and the frame is made to 0.25 mm or less. According to the invention, as the result of experiments, the colliding speed becomes smaller and even if the Oldham ring inclines and makes collisions with the swivel scroll or the frame, it is found that the shock force becomes less. This means that increase of the inclining vibrations of the Oldham ring is suppressed and increase of noises due to shocks is prevented. And yet, this effect is obtained only by the ring portion of the Oldham ring being adjusted of its thickness, and as compared with making adjustment of thickness of individual key portions or making control of flatness between individual key potions, suppression of the inclining vibrations of the Oldham ring is facilitated. According to the invention, increase of the inclining vibrations of the Oldham ring caused for reason of flatness of the Oldham ring is also suppressed. BRIEF DESCRIPTION OF THE DRAWINGS: In the accompanying drawings; Fig. 1 is a cross sectional view showing an Oldham ring and its surroundings of a scroll type compressor of a first preferred embodiment according to the present invention. Fig. 2(a) is a diagrammatic view showing a state where the inclining vibrations of the Oldham ring are occurring increasingly. Fig. 2(b) is a diagrammatic view showing a state where the inclining vibrations of the Oldham ring are suppressed of increase by the gap being restricted. Fig. 3 is a side view showing an Oldham ring of a scroll type compressor of a second preferred embodiment according to the present invention. Fig. 4 is a cross sectional view showing a structure of a scroll type compressor. Fig. 5 is a side view showing said Oldham ring and its surroundings. Fig. 6 is an explanatory perspective view showing a structure of said Oldham ring. Fig. 7 is an explanatory view showing how the inclining vibrations of said Oldham ring are generated. DESCRIPTION OF THE PREFERRED EMBODIMENTS: Herebelow, the present invention is described based on the first preferred embodiment shown in Figs. 1 and 2. As the entire structure of a scroll type fluid machine is same as that of Fig. 4 described above in the item of the prior art, said Fig. 4 is commonly used as an entire view of a scroll type fluid machine, an entire description of a scroll type fluid machine is omitted and a main part of the invention is described here. That is, Fig. 1 shows an Oldham ring 18 being disposed between a swivel scroll 2 and a frame 10. Incidentally, the frame 10 supports a rotational shaft 13 to drive the swivel scroll 2 to make revolutional swivel motions. The Oldham ring 18, being same as that described before, is so constructed that it has a ring portion 19 to be located between an end plate 6 of the swivel scroll 2 and the frame 10, and at two places where a diametrical line of the ring crosses the ring portion 19, two swivel side keys 20, 20 are formed, in a pair, projectingly from the end faces of the ring portion 19 as an integral body with the ring portion 19 and at two places of the ring portion 19 on a diametrical line rectangularly crossing the above-mentioned diametrical line, two stationary side keys 21, 21 are formed, in a pair, projectingly from the opposite end faces of the ring portion 19 as an integral body with the ring portion 19. The swivel side keys 20 of the Oldham ring 18 are fitted slidably in key ways 22 formed on the lower face of the end plate 6 of the swivel scroll 2, the stationary side keys 21 are fitted slidably in key ways 23 formed on the upper face of the frame 10 and the swivel scroll 2 makes revolutional swivel motions, without making rotational motions, around the central axis of a stationary scroll 1. In said Oldham ring 18, the ratio of the amount of gap between the swivel scroll 2 and the frame 10 to the radius r of the ring portion 19 is limited within a predetermined value. That is, where the distance between the end plate 6 of the swivel scroll 2 and the frame 10 is s and the thickness of the ring portion 19 of the Oldham ring 18 is t, the ratio of the gap δ, formed as (s-t), to the radius r of the ring portion 19 of said Oldham ring 18 is set so that δ/r is 0.01 or less. At the time of a high speed rotation of a scroll type fluid machine made with such setting, even if the Oldham ring 18 inclines and makes collisions with the end plate 6 of the swivel scroll 2 or with the frame 10, it is found that the colliding speed becomes smaller and the shock force caused thereby also becomes smaller. That is, there are taken place experiments for study of increase of the shock sounds wherein a scroll type fluid machine is operated with a high speed rotation with said gap δ (the gap formed as the difference of the distance s between the end plate 6 of the swivel scroll 2 and the frame 10 and the thickness t of the ring portion 19 of the Oldham ring 18) being variously changed to the radius r of the ring portion 19 of the Oldham ring 18, and a resulted difference as shown in Fig. 2 is obtained. Fig. 2 shows a difference of the vibrations of the frame portion between a state where shocks occur and a state where shocks do not occur, wherein Fig. 2(a) shows a state where the shocks occur and Fig. 2(b) shows a state where the shocks do not occur. From the above experiments, it is confirmed that remarkable increases of the shock sounds occur at the places pointed by fingers of Fig. 2(a) at the time when the value of δ/r is more than 0.01 and do not occur at the time when the value of δ/r is 0.01 or less as seen in Fig. 2(b). The reason for that is considered because, at the time of δ/r being 0.01 or less, the colliding speed of the Oldham ring 18 is small and even if the Oldham ring 18 inclines and makes collisions with the swivel scroll 2 or the frame 10, only the small shock forces occur. That is, increase of the inclining vibrations of the Oldham ring can be suppressed. As a result, shocks can be avoided and increase of noises due to the shocks can be prevented. And yet, this effect is obtained only by the ring portion 19 of the Oldham ring 18 being adjusted of its thickness t, and as compared with making adjustment of thickness of individual key portions or making control of flatness between individual key portions in the prior art, suppression of the inclining vibrations of the Oldham ring is facilitated. Fig. 3 shows a second preferred embodiment according to the present invention. In the second preferred embodiment, in addition to the provision of δ/r as mentioned in the first preferred embodiment, the warp γ of the ring portion 19 of the Oldham ring 18 located between the end plate 6 of the swivel scroll 2 and the frame 10 is restricted. More concretely, the warp γ of the ring portion 19 is set to 0.25 mm or less. By making such setting of the warp of the ring portion 19, increase of the inclining vibrations of the Oldham ring 18 caused for reason of flatness of the Oldham ring 18 can also be suppressed. That is, in the scroll type fluid machine, if the flatness of the ring portion 19 of the Oldham ring is not good enough, due to the revolutional swivel motions, being accompanied by conical motions, of the swivel scroll 2 in the compression process, the inclining vibrations of the Oldham ring 18 show movements to be increased. Here, there are taken place experiments wherein a scroll type fluid machine is operated with the warp γ of the ring portion 19 being variously changed and as a result, it is confirmed that increase of the inclining vibrations of the Oldham ring 18 occurs at the time when the warp γ of the ring portion 19 of the Oldham ring 18 is more than 0.25 mm and does not occur at the time when the warp γ is 0.25 mm or less. That is, by the warp of the ring portion 19 being restricted, the inclining vibrations of the Oldham ring 18 can be further avoided and increase of noises can be further prevented. Incidentally, the present invention is applied to a scroll type compressor in the above, but needless to mention, not limited thereto, it can be applied also to other scroll type fluid machines like a scroll type expander etc. As mentioned above, according to the invention, by the gap formed by the difference of the distance between the end plate of the swivel scroll and the frame and the thickness of the ring portion of the Oldham ring between the end plate of the swivel scroll and the frame being restricted, increase of the inclining vibrations of the Oldham ring is suppressed, shocks due to said Oldham ring is avoided and increase of noises due to said shocks can be prevented. And yet, this effect is obtained only by the ring portion of the Oldham ring being adjusted of its thickness, and as compared with making adjustment of thickness of individual key portions or making control of flatness between individual key portions, suppression of the inclining vibrations of the Oldham ring is facilitated. According to the invention, in addition to the above-mentioned effect, increase of the inclining vibrations of said Oldham ring caused for reason of flatness of the Oldham ring can also be suppressed and a further effect of shock avoidance and noise prevention can be obtained.

Claims: A scroll type fluid machine comprising: a stationary scroll (1) and a swivel scroll (2) engaged with each other, said swivel scroll (2) having an end plate (6); a frame (10), said stationary scroll (1) being stationary relativ to said frame (10), and said end plate (6) of said swivel scroll (2) and said frame (10) being spaced a distance s from each other; and an Oldham ring (18) disposed between said end plate (6) of said swivel scroll (2) and said frame (10), said Oldham ring (18) comprising a ring portion (19) and key portions (20,21) on said ring portion (19) engaging said frame (10) and said end plate (6) of said swivel scroll (2), said ring portion (19) having a thickness t and a radius r; wherein a gap δ is defined by (s-t) and δ/r is 0.01 or less; characterized in that a warp γ of said ring portion (19) of said Oldham ring (18) located between said end plate (6) of said swivel scroll (2) and said frame (10) is 0.25 mm or less.

Inventors: HIROOKA KATSUMI, KOBAYASHI HIROYUKI, SATO KAZUHIRO, HIROOKA, KATSUMI, KOBAYASHI, HIROYUKI, SATO, KAZUHIRO, Hirooka, Katsumi, c/o Air Con&amp;Ref Machinery Works, Kobayashi, Hiroyuki, c/o Nagoya Res. &amp; Dev. Ctr, Sato, Kazuhiro, c/o Nagoya Res. &amp; Dev. Ctr
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1996
Main classification: F04C18
IPC codes: F01C17, F04C18