Pumps – Correlated pump and motor or clutch control
Patent
1997-01-17
1999-04-27
Freay, Charles G.
Pumps
Correlated pump and motor or clutch control
417 441, 417310, 41742312, 417440, F04B 3504
Patent
active
058972994
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an anti-reverse rotation apparatus of a compressor and relates to, for example, measures for avoiding an impeller of a centrifugal compressor from rotating in reverse due to high pressure working from a discharge side of the compressor when the centrifugal compressor is deactivated.
BACKGROUND ART
As a compressor used in a refrigerating circuit of an air conditioner, there is known a conventional centrifugal compressor as disclosed in Japanese Patent Application Laid-Open Gazette No. 5-340386.
The above conventional centrifugal compressor will be schematically described below. As shown in FIG. 6, in a casing (a), a motor room (b) and an impeller room (c) are formed. The motor room (b) contains a motor (d) and the impeller room (c) contains an impeller (rotary vanes) (f) directly connected to a driving shaft (e) of the motor (d). Further, the casing (a) is connected to an inlet pipe (g) as opposed to a center portion of the impeller (f) and is connected to a discharge pipe (h) as opposed to an outer peripheral portion of the impeller (f).
When the motor (d) is operated to rotate the impeller (f), a fluid is sucked into the impeller room (c) through the inlet pipe (g), is subjected to centrifugal force into a radially outward flow, is compressed, and is then discharged through the discharge pipe (h).
Upper and lower ends of the driving shaft (e) are inserted into respective through holes (i1, i1) of bearing plates (i, i) fixed on the inner surface of the casing (a). Further, the outer periphery of the driving shaft (e) has herringbone grooves (e1, e1) formed at respective positions opposed to the inner peripheries of the through holes (i1, i1). The herringbone grooves (e1, e1) forms dynamic pressure gas bearings between the driving shaft (e) and the bearing plates (i, i).
In detail, the rotation of the driving shaft (e) produces respective gas layers due to gas pressure between the driving shaft (e) and the inner peripheries of the through holes (i1, i1) so that the driving shaft (e) is rotatably supported by the gas layers in non-contact with the bearing plates (i, i).
The dynamic pressure gas bearing of this kind produces a gas layer only by a rotation of the driving shaft (e) in a single direction to rotatably support the driving shaft (e). Therefore, the dynamic pressure gas bearing functions as a bearing only when the driving shaft (e) rotates in a rotational direction of the impeller (f) under operation of fluid compression of the compressor.
Problems to be Solved
In such a centrifugal compressor, during running operation, the inside of the inlet pipe (g) is put into a low pressure state under reduced pressure due to fluid suction, whereas the inside of the discharge pipe (h) is put into a high pressure state due to a compressed fluid.
Hence, at the time when the rotation of the impeller (f) is stopped by a deactivating operation of the centrifugal compressor, the inside of the discharge pipe (h) located downstream from the impeller (f) becomes higher in pressure than the inside of the inlet pipe (g) upstream from the impeller (f). This higher pressure acts on the inlet pipe (g) through the impeller room (c). As a result, the higher pressure may rotate the impeller (f) opposite to the rotational direction of the impeller (f) under operation of fluid compression.
In such a condition, the driving shaft (e) also rotates in reverse. When the driving shaft (e) rotates in reverse, the bearing functions of the dynamic pressure gas bearings cannot be performed and in some instances, the driving shaft (e) may seize up on the bearing plates (i, i).
In view of the foregoing problems, the present invention has been made and has its object of preventing respective reverse rotations of a rotor and a driving shaft of a compressor by preventing the action of a high pressure on the rotor from a discharge side of the compressor when the compressor is deactivated.
DISCLOSURE OF INVENTION
Summary of the Invention
In the present invention, when a compressor is deactiva
REFERENCES:
patent: 3406897 (1968-10-01), Diels
patent: 4627788 (1986-12-01), Keyes, IV. et al.
patent: 4697980 (1987-10-01), Keyes, IV. et al.
patent: 4764085 (1988-08-01), Jesinger
patent: 5607288 (1997-03-01), Wallis et al.
"Constraints Complicate Centrifugal Compressor Depressurization" Oil & Gas Jornal, XP-002068741, vol. 91, No. 19, May 10, 1993, pp. 50-54.
Daikin Industries Ltd.
Ferguson Jr. Gerald J.
Freay Charles G.
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