Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
1997-09-02
2001-04-03
Freay, Charles G (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C417S368000, C417S372000, C417S201000, C418S055600, C418S101000
Reexamination Certificate
active
06210132
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a compressor of the type used for air compressor, refrigeration, air-conditioning, etc., and more particularly to an oil-free scroll compressor.
An oil-free scroll compressor, which does not use oil, such as a lubricating oil, for the flow passage of the operation gas, is a well known compressor for use in air compressor, refrigeration, and air condition. In this oil-free scroll compressor, two sealed spaces are defined by wraps and end plates on the outer wall surface of an orbiting scroll wrap and a stationary scroll wrap by combining the orbiting scroll and the stationary scroll, each of which is equipped with spiral wraps perpendicular to an end plate, while the inside of the wraps face one another. The sealed spaces move towards the center portion due to the relative motion of both scrolls. As their volumes thus decrease, a gas sucked from the outer peripheral sides of these scrolls is compressed and is discharged from a discharge port disposed at the center portion of the stationary scroll. When the operation gas is compressed in this way by the relative motion of the orbiting scroll and the stationary scroll, the scroll compressor generates heat. This also holds true for other types of compressors handling gas. Japanese Patent Laid-Open No. 217580/1995 describes a two-stage oil-free screw compressor having a small capacity of 22 kW to 37 kW, for example, wherein the first stage discharge air temperature reaches about 190 to about 240° C. Therefore, in the scroll compressor which is of the same displacement type, heat generation of a similar level can be expected if the compressor ratio, etc., is the same.
When the compressor generates heat, the clearance of each portion of the compressor changes from the design value due to thermal deformation, and the compressor becomes less reliable. At the same time, performance of the compressor drops due to a leakage from clearances caused by the thermal deformation, etc. Therefore, a cooling system for effectively guiding the heat generated inside the compressor to the outside has been necessary, and an example of such a system is described in Japanese Patent Laid-Open No. 217580/1995 and Japanese Utility Model Laid-Open No. 104384/1983.
According to Japanese Laid-Open No. 217580/1995, a pre-cooler for primarily cooling a gas discharged from a low pressure stage compressor element is interposed between the low pressure stage compressor main body and an intercooler in a two-stage oilless scroll compressor, and this pre-cooler is accommodated inside an exhaust duct and is cooled by exhaust air flowing through each cooler. This technique retains the effect of dissipating heat generated by the scroll compressor from the compressor to a certain extent, but is not yet sufficient for improving the reliability by cooling the compressor as a whole. In other words, though this approach considers how to cool the cooler on the discharge side of the cooling fan, it does not take cooling of the compressor element disposed on the suction side into consideration. In this regard, if the compressor element which generates a high compression heat is cooled by air, the mass of cooling air increases and a problem develops in that the noise increases due to the increase of a flow velocity inside the exhaust duct. Additionally, the compressor element, the cooling fan, the cooler, etc., are disposed plane-wise, and require a large installing space. Therefore, a reduction of the size of the compressor can not be achieved.
According to Japanese Utility Model Laid-Open No. 104384/1983, on the other hand, a compressor driven by a vertical motor is disposed below the motor, a blower is disposed above the motor, and they are accommodated in a casing so as to cool the compressor as a whole using the blower. According to this technique, however, the air steam around each portion of the compressor changes depending on the flow passage resistance, and all the heat generating portions cannot always be cooled.
SUMMARY OF THE INVENTION
It is therefore a main object of the present invention to achieve a low noise oil-free scroll compressor which can eliminate the problems described above.
It is another object of the present invention to achieve an oil-free scroll compressor which does not need a large installing space.
An oil-free scroll compressor, of the type to which the invention applies, comprises scroll compressor element having an orbiting scroll and a stationary scroll; a motor for driving the scroll compressor element; a cooler for cooling an operation gas compressed by the scroll compressor element; a cooling fan for blasting cooling air subjected to heat-exchange with the operation gas by the cooler; and a casing for accommodating these members. A first embodiment of the present invention for accomplishing the objects described above employs a construction wherein partition means for partitioning a suction flow passage and a discharge flow passage of the cooling fan is provided in the casing. Preferably, this partition means divides the inside of the casing into two chambers with the suction side of the cooling fan as a part thereof.
Preferably, a dryer for dehumidifying the operation gas cooled by the cooler is accommodated in the casing, a discharge port for cooling air is formed on the ceiling plate portion of the casing, a suction port for cooling air is formed on the side portion of the casing, and a first flow passage, through which cooling air introduced via the suction port flows from above to below, a second flow passage, through which cooling air flows from below to above to flows out via the discharge port, and a third flow passage, connecting the first and second flow passage, are exclusively disposed in the casing. Preferably, the second and third flow passages are constituted by a duct respectively.
A second embodiment of the present invention for accomplishing the objects described above employs a construction wherein the motor and the scroll compressor elements are disposed in a stratified form, and the cooling fan and the cooler are disposed in a stratified form. These two stratified arrangements are preferably juxtaposed on the floor surface of the casing.
Preferably, the casing is shaped into a rectangular parallelepiped, the motor is accommodated at the lowermost portion of this rectangular parallelepiped through insulating means for vibration-insulation from the casing, the duct is disposed above the motor, the scroll compressor element is disposed above the duct, a dryer for dehumidifying the operating as compressed by the scroll compressor element, the cooler is interconnected to the scroll compressor element, partition means is a duct defining the cooler and the cooling fan from other members, an exhaust port is formed on the ceiling plate side of the casing, and a suction port is formed on the side surface of the casing on the opposite side to the cooling fan.
Further, a first flow passage through which cooling air flows from above to below, a second flow passage through which cooling air flows from below to above and a third flow passage which connects these first and second flow passages are exclusively disposed inside the casing. Further, the second and third flow passages are preferably constituted by a duct.
In an oil-free scroll compressor of the type wherein a scroll compressor element, a motor and a cooler accommodated inside a casing are cooled by a cooling fan fitted to a double-end motor, the third embodiment of the present invention for accomplishing the afore-mentioned objects comprises a duct for communicating the suction side of the cooling fan and the scroll compressor elements; and an exhaust duct with a built-in cooler disposed on the discharge side of the cooling fan. Preferably, the duct and the exhaust duct are disposed in such a manner as to cross each other substantially orthogonally.
Preferably, a duct for communicating the suction side of the cooling fan and the scroll compressor element and an exhaust duct with a built-in cooler on the discharge side of
Kawabata Natsuki
Kawano Isamu
Shiinoki Kazuaki
Suzuki Akira
Antonelli Terry Stout & Kraus LLP
Freay Charles G
Hitachi , Ltd.
Tyler Cheryl J.
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