Multistage rotary compressor

Abstract

The present invention relates to a multistage rotary compressor. In the multistage rotary compressor, a motor-operating element 5 and a rotary compressing element 6 are provided at upper and lower portions in a closed vessel 1. In the rotary compressing element 6, a low stage side rotary compressing element 9 and a high stage side rotary compressing element 11 are positioned on the upper and lower sides respectively. An upper supporting member 12 is attached onto the low stage side rotary compressing element 9, and a substantially cup-shaped cover material 16 is attached onto the upper supporting member 12 to close an opening surface of a muffling chamber 12b formed in the upper supporting member 12. The substantially cup-shaped cover material 16 is formed in a high dimension so that the upper end of the cover material 16 is positioned at an upper end or near an upper end of a bearing portion 12a formed in the upper supporting member 12. Further, a discharge hole 16b for discharging a refrigerant gas is provided in the upper end surface of the cover material 16 near an outer diameter portion of the bearing portion 12a. Consequently, the level h of the oil surface for oil filled in the closed vessel 1 can be set so as to be near the upper end of the cover material 16. According to the present invention, the amount of oil filled in the closed vessel can be increased and the oil separation in the closed vessel can be efficiently made.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a multistage rotary compressor, and more specifically it relates to a multistage rotary compressor that can increase the amount of oil filled into a closed vessel and can efficiently make oil separation in the closed vessel. [0003] 2. Description of the Related Art [0004] A multistage rotary compressor including a motor-operating element and a rotary compressing element driven by this motor-operating element disposed in a closed vessel has been known. For example, a two-stage rotary compressor shown in FIG. 4 will be described. In FIG. 4, an upper portion in a closed vessel A is provided with a motor-operating element B composed of a stator and a rotor, the rotor is journalled to an upper end portion of a rotating shaft C, a lower portion in the closed vessel A is provided with a rotary compressing element G composed of a low stage side rotary compressing element E and a high stage s...

AI Technical Summary

Benefits of technology

[0012] The present invention was made to solve such a problem in a conventional multistage rotary compressor and the object of the present invention is to provide a multistage rotary compressor in which the amount of oil filled into a closed vessel A can be increased and oil separation in the closed vessel can be efficiently made.

[0016] According to the first aspect of the invention, since in the multistage rotary compressor comprising a plurality of rotary compressing elements in a closed vessel, discharge refrigerant gas in any one of said rotary compressing elements being discharged into the closed vessel, and discharge refrigerant gas in other rotary compressing elements being discharged outside the closed vessel, a cover material, which defines a discharge muffling chamber, is mounted onto the upper rotary compressing element, and when oil is filled into said closed vessel, the oil level of said filled oil is designed so as to be slightly lower than the discharge hole formed in the cover material, the amount of oil filled into the closed vessel can be made more than that of a conventional case. Therefore, even if the level of the oil surface is lowered during the operation, a situation in which oil cannot be sucked up from the oil reservoir does not occur, a lack of lubrication in the sliding portion and the like of the rotating shaft is removed to protect them from wear and at the same time the compressive performance can be maintained significantly.

[0017] Further, according to the second aspect of the invention, since in the inside intermediate pressure type multistage rotary compressor, the low stage side rotary compressing element of the rotary compressing elements is positioned on the high stage side rotary compressing element, the upper supporting member is provided on the low stage side rotary compressing element and the substantially cup-shaped cover material is provided on the upper supporting member in such a manner that the height of the cover material is extended to the position of an upper end of the bearing portion in the upper supporting member, the amount of oil filled into the closed vessel can be made more. Therefore, even if the level of the oil surface is lowered during the operation, a situation in which oil cannot be sucked up from the oil reservoir does not occur, a lack of lubrication in the sliding portion and the like of the rotating shaft is removed to protect them from wear and at the same time the compressive performance can be maintained significantly. Further, since the intermediate pressure refrigerant gas compressed by the low stage side rotary compressing element is discharged from the discharge hole provided on an upper end surface of the substantially cup-shaped cover material near an outer diameter portion of the bearing portion, the refrigerant gas can be blown onto a lower end portion of the rotor positioned just near the discharge hole. Consequently, oil contained in the intermediate pressure refrigerant gas discharged from the discharge hole can be efficiently separated in the closed vessel.

[0018] Further, according to the third aspect of the invention, since in the inside intermediate pressure type multistage rotary compressor, the high stage side rotary compressing element of the rotary compressing element is positioned on the low stage side rotary compressing element, the upper supporting member is provided on the high stage side rotary compressing element and the substantially cup-shaped cover material is provided on the upper supporting member in such a manner that the height of the cover material is extended to the position of an upper end of the bearing portion in the upper supporting member, the amount of oil filled into the closed vessel can be made more. Therefore, even if the level of the oil surface is lowered during the operation, a situation in which oil cannot be sucked up from the oil reservoir does not occur, a lack of lubrication in the sliding portion and the like of the rotating shaft is removed to protect them from wear and at the same time the compressive performance can be maintained significantly. Further, since the high pressure refrigerant gas compressed by the high stage side rotary compressing element is discharged from the discharge hole provided on an upper end surface of the substantially cup-shaped cover material near an outer diameter portion of the bearing portion, the refrigerant gas can be blown onto a lower end portion of the rotor positioned just near the discharge hole. Consequently, oil contained in the high pressure refrigerant gas discharged from the discharge hole can be efficiently separated in the closed vessel.

[0019] Further, according to the third aspect of the invention, in the multistage rotary compressing element according to the first or second aspect, since the level of oil filled in the closed vessel is set near the upper end of the substantially cup-shaped cover material, the amount of oil in the oil reservoir formed on the bottom portion of the closed vessel can be increased. Accordingly, a suction of oil from the oil reservoir during operation can be ensured, a lack of lubrication in the sliding portion and the like of the rotating shaft is removed to protect them from wear and at the same time the compressive performance can be maintained significantly.

Problems solved by technology

However, the level of the oil surface in the oil reservoir at a bottom portion of the closed vessel A cannot be made at a higher position than the cover plate R. If the level of the oil surface in the oil reservoir exceeds the cover plate R, oil flows into the oil reservoir from an outlet of a passage (not shown) for discharging the intermediate pressure refrigerant gas compressed by the low stage side rotary compressing element into the closed vessel A so that the gas discharge is hindered, resulting in that the compression function is remarkably reduced.

Nevertheless the oil cannot be perfectly separated and a part of oil remains in the refrigerant gas.

However, since the outlet of the passage (not shown) is not near to the lower end portion of the motor-operating element B, there is a problem that the oil separation in the refrigerant gas in the closed vessel cannot be efficiently made.

Images