SCROLL COMPRESSOR

Abstract: A scroll compressor having a fixed scroll member (7) and an orbiting scroll member (8). The fixed scroll member (7) has an end plate (13) and a wrap (14) attached to the end plate in an involute curve and, similarly, the orbiting scroll member (8) has an end plate (16) and a wrap (17) attached to the end plate thereof in a juxtaposed relation with the fixed scroll member so that the wraps of the two scroll members are fitted closely together. A check valve (20) is provided so that an exhaust opening of the end plate is always opened when the compressor is in its operation and closed only when the operation is stopped.

Description: The invention relates to a scroll compressor according to the preamble of claim 1. Such a scroll compressor is disclosed in JP-A-55-35151 and JP-K-56-28237 which will be explained in connection with Figure 4. The scroll compressor 50 has a fixed scroll member 53 having a wrap 52 in an involute curve on an end plate 51, and an orbiting scroll member 56 which is formed as similar as the fixed scroll member 53 and has an end plate 54 and a wrap 55 so that the two scroll members are arranged in a juxtaposed relation with the two wraps being fitted closely together. A stationary member 58 is fixed to the fixed scroll member 53 and an Oldam ring 57 is provided between the stationary member 58 and the orbiting scroll member 56. The fixed scroll member 53 has an exhaust opening 59 at a center of the end plate 51 so that a gas which has been compressed by a gas pocket formed by the wraps of the two scroll members 53, 56 is exhausted from the exhaust opening 59. The exhaust opening 59 is opened and closed by a check valve 61 to prevent a back-flow of a fluid, which has been compressed and exhausted from the exhaust opening 59, to a lower pressure side in the scroll compressor when the operation of the system is stopped so that a reversal rotation of the orbiting scroll member is prevented. However, this known scroll compressor has the disadvantage that the check valve is repeatedly opened and closed during the operation of the compressor so that noise is produced by repeated valve operation. That is also the case if the one-way valve known from US-A-3 606 588 is used for a scroll compressor. It is the object of the invention to provide a scroll compressor of the above mentioned kind in such a way that the one-way valve is maintained open during operation of the compressor and is closed only when the operation is stopped so that the noise arising from the valve operation can be reduced. This object is achieved by the features in the characterizing part of claim 1. The invention is described by way of an example in connection with the drawings. Figure 1 is a sectional elevation of a scroll compressor according to the present inventnion, Figure 2 is a sectional view of a check valve attached to an end plate of a fixed sroll member of the scroll compressor shwon in Figure 1, Figure 3 is a plan view of the check valve shown in Figure 2, and Figure 4 is an illustration of an example of the conventional scroll compressor. PREFERRED EMBODIMENTS OF THE INVENTION A preferred embodiment of the present invention will be described with reference to Figures 1 through 3. Referring first to Figure 1, a hermetically sealed container 1 includes therein a compression device which is generally indicated at 2 at its upper portion and an electric motor 4 at its lower portion. The compression device 2 has a frame 6 which is fixed to an inner surface of the container 1 and has a bearing portion 5 for a driving shaft 3, a fixed scroll member 7 attached to the frame 6 and having a boss 9, an orbiting scroll member 8 arranged in a juxtaposed relation with the fixed scroll member 7 with their wraps being fitted closely together, which will be described presently, a slide bearing 11 which journals a crank portion 10 of the driving shaft 3 fitted to the boss of the orbiting scroll member 8, and an Oldham ring 12 which is arranged to the frame 6 to prevent a rotation of the orbiting scroll member 8 relative to the fixed scroll member. The fixed scroll member 7 has an end plate 13, a wrap 14 attached to a surface of the end plate 13 in an upstanding posture and substantially formed in an involute curve, and an annular wall 15 fixed to the frame 6. Similarly, the orbiting scroll member 8 has an end plate 16 positioned inside the annular wall 15 of the fixed scroll member 7, and a wrap 17 attached to a surface of the end plate 16 in an upstanding posture and substantially formed in an involute curve. The fixed scroll member 7 is arranged in a juxtaposed relation with the orbiting scroll member 8 so that the wraps 14, 15 are fitted closely together in an opposed relation to form a gas pocket 18, which is moved toward the center of the wraps as a volume of the gas pocket 18 is decreased. The fixed scroll member 7 has an exhaust opening 19 formed at a center of the end plate 13 thereof, and a one-way valve or a check valve 20 is disposed adjacent to the exhaust opening 19 on the upper surface of the end plate 13 to thereby prevent a back-flow of a fluid which has been discharged from the exhaust opening 19. With reference to Figures 2 and 3, the check valve 20 has a leaf valve 21 and a reinforcing plate 22, which is warped away from the opening 19 as illustrated, and these elements 21, 22 are fixed to the end plate 13 by a bolt 23. The leaf valve 21 is also warped toward the reinforcing plate 22 and away from the exhaust opening 19. The reinforcing plate 22 has an aperture 24 at a warped, extended portion so that a back-flowing fluid can effect directly on the leaf valve 21 through the aperture 24. Thus, when the leaf valve 21 is temporarily and unexpectedly adhered to the reinforcing plate 22 by an oil and the like, the exhaust opening 19 is closed by the leaf valve 21 by the effect of the gas. If necessary, the leaf valve 21 can be extended beyond the end of the reinforcing plate 22 to facilitate an operation of the valve when the leaf valve 21 is adhered to the reinforcing plate as above. Referring back to Figure 1, a discharge tube 25 is disposed at an upper wall of the sealed container 1 and opened to an upper chamber 26 above the end plate 13 of the fixed scroll member 7. A suction tube 27 is disposed at an upper side wall of the container and opened to a lower chamber 28. In operation, the orbiting scroll member 8 is driven by the crank portion 10 of the driving shaft 3 to provide an orbiting movement of the orbiting scroll member 8 relative to the fixed scroll member 7 so that the gas pocket 18 confined by the wraps of the two scroll members 7, 8 is moved to the center thereof as a volume of the gas pocket 18 is decreased gradually. Thus, the gas in the gas pocket 18 is compressed and then moved to the center of the wraps and thereafter exhausted out of the exhaust opening 19. The gas exhausted out of the opening 19 is discharged out of the container 1 through the upper chamber 26. The leaf valve 21 of the check valve 20 is formed warped toward the reinforcing plate 22 to maintain the exhaust opening opened during operation of the compressor holding the leaf valve opening. Thus, a noise of the valve can be avoided. When the operation of the compressor is stopped, the pressure difference between the upper chamber 26 and the lower chamber 28 permits the gas in the upper chamber 26 to flow back toward the lower chamber 28 through the exhaust opening 19 and, at this moment, the leaf valve 21 is actuated to close the exhaust opening 19 by the back-flowing gas. Consequently, the gas in the upper chamber 26 does not flow back to the lower chamber 28 through the wraps of the two scroll members 7, 8. Therefore, a reversal movement of the orbiting scroll member 8 can be prevented except for only a little reversal rotation due to a residual gas which was left in the gas pocket 18, and a noise due to the reversal rotation of the orbiting scroll member 8. According to the present invention, the check valve is provided to maintain the exhaust opening to be opened at the time of operation of the compressor so that a noise of the valve is eliminated, and close the exhaust opening when the operation of compressor is stopped to prevent the reversal rotation of the orbiting scroll member.

Claims: A scroll compressor comprising: a fixed scroll member (7) having an end plate (13) and a wrap (14) attached to the surface of said end plate in an involute curve; an orbiting scroll member (8) having an end plate (16) and a wrap (17) attached to a surface of said end plate of the orbiting scroll member (8) in a juxtaposed relation with said fixed scroll member (7) so that the wraps (14,17) of the two scroll members are fitted closely together to form a plurality of sealed spaces for compression; said end plate (13) of said fixed scroll member (7) having an exhaust opening (19), said exhaust opening being connected to the sealed space of completed compression process to permit a compressed gas in said sealed space to be discharged out of said wraps; said end plate (13) of said fixed scroll member (7) having a one-way valve (20) at said exhaust opening (19) for opening and closing said exhaust opening, wherein said one-way valve (20) has a leaf valve (21) and a reinforcing plate (22), said reinforcing plate being warped in a direction away from said exhaust opening (19), characterized in that said leaf valve (21) is warped toward and adjacent to said reinforcing plate (22) for maintaining said exhaust opening (19) normally open and always open during the operation of the compressor, and said leaf valve (21) being separately movable away from said reinforcing plate (22) for closing said exhaust opening (19) only when the operation of the compressor is stopped to provide a pressure difference between the exhaust opening and said sealed space. A scroll compressor according to claim 1, wherein said reinforcing plate (22) has an aperture (24) therein for allowing gas therethrough to press against said leaf valve (21) for closing said exhaust opening (19) when the compressor is stopped.

Inventors: ISHIAI, YOSHIO
Applicants: SANYO ELECTRIC CO., LTD.
Application year: 1987
Main classification: F04C18
IPC codes: F04C29, F16K15, F16K21, F04C18, F04B39