BACKGROUND

1. Field

A scroll compressor is disclosed herein.

2. Background

In general, a compressor is applicable to a vapor compression type refrigeration cycle (hereinafter, referred to as a “refrigeration cycle”), such as a refrigerator, or au air conditioner, for example. A compressor can be typically divided into a hermetic type compressor, in which an electric motor drive, which is a typical electromotor, and a compression device operated by the electric motor drive are provided together at an inner space of a sealed casing, and an open type compressor, in which the electric motor drive is additionally provided at an outside of the casing. The hermetic compressor is mostly used for household or commercial refrigeration devices.

Further, compressors can be divided into a reciprocating type, a rotary type, or a scroll type, for example, according to a type of compressing of a refrigerant. The reciprocating type compressor is a type that compresses a refrigerant while a piston drive portion linearly moves a piston. The rotary type compressor is a type that compresses a refrigerant using a rolling piston that performs an eccentric rotational movement in a compression space of the cylinder and a vane in contact with the rolling piston to partition the compression space of the cylinder into a suction chamber and a discharge chamber. The scroll compressor is a compressor in which a fixed scroll is fixed to an inner space of the hermetic container, and a plurality of compression chambers including of a suction chamber, an intermediate pressure chamber, and a discharge chamber is consecutively formed between a fixed wrap of the fixed scroll and an orbiting wrap of the orbiting wrap while the orbiting scroll engaged with the fixed scroll performs an orbiting movement. The scroll compressor is widely used for air conditioners, for example, to compress refrigerant due to an advantage of obtaining a relatively high compression ratio compared to the other types of compressors, as well as obtaining a stable torque as suction, compression, and discharge strokes are smoothly carried out.

Furthermore, a compressor can be divided into an upper compression type and a lower compression type according to a location of the electric motor drive and compression device. The upper compression type is a type in which the compression device is located at an upper side of the electric motor drive, and the lower compression type is a type in which the compression device is located at a lower side of the electric motor drive. In particular, in a case of the lower compression type, refrigerant discharged into an internal space of the casing moves to a discharge pipe located at an upper portion of a casing, while oil is recovered to an oil storage space, and thus, there is a concern that oil may be mixed with refrigerant to be discharged out of the compressor or pushed by a pressure of the refrigerant to stagnate at an upper side of the electric motor drive during the process. According to embodiments disclosed herein, a technique in which a passage to recover oil and a passage to discharge a refrigerant may be divided within the casing to reduce oil spill will be described using a high-pressure, lower compression type scroll compressor (hereinafter, referred to as a “lower compression type scroll compressor”) as an example.

FIG. 1is a cross-sectional view of a lower compression type scroll compressor according to the related art. As illustrated in the drawing, a lower compression type scroll compressor according to the related art may include an electric motor drive2provided in an internal space of a casing1and having a stator and a rotor, a compression unit or device3provided at a lower side of the electric motor drive2, and a rotational shaft5that transmits a rotational force of the electric motor drive2to the compression device3. A refrigerant discharge pipe16may be provided at an upper portion of the casing1.

A passage (Pm) to guide oil separated from refrigerant at an upper side space of the electric motor drive2to be recovered to an oil storage space (V3) at an upper side space of the electric motor drive2at a lower side of the compression device3while at the same time guiding refrigerant discharged from the compression device3to move in a direction of the refrigerant discharge pipe16may be formed on an inner circumferential surface of the casing1and an outer circumferential surface of the electric motor drive2or an inner portion of the electric motor drive2.

According to the foregoing lower compression type scroll compressor according to the related art, refrigerant and oil discharged from the compression device3may move to an upper side of the electric motor drive2through the passage (Pm) provided in the electric motor drive2, and then, may be discharged to an outside of the compressor through the refrigerant discharge pipe16. At the same time, oil separated from refrigerant between the electric motor drive2and the compression device3may move to the oil storage space (V3) through a passage (Pc) provided in the compression device3, while oil separated from refrigerant at the upper side of the electric motor drive2may moves to the oil storage space (V3) at the lower side of the compressor through the passage (Pm) provided in the electric motor drive2and the passage (Pc) provided in the compression device3.

Discharge refrigerant discharged into the internal space of the casing1from the compression device3may include oil. Recovery of oil contained in the discharged refrigerant is a key factor for system efficiency and compressor reliability.

For the upper compression type scroll compressor, the compression device may be located at an upper side of the casing, and thus, refrigerant coming out of the compression device may be almost directly discharged through the refrigerant discharge pipe, and has a short period of discharge time, thus resulting in a low oil separation efficiency. In contrast, for the lower compression type scroll compressor, the compression device3is located at the lower side of the casing1, and thus, refrigerant coming out of the compression device3passes through other spaces to be discharged through the refrigerant discharge pipe16, and thus, there is a sufficient time for oil to be separated therefrom before the discharge time, thus resulting in a relatively high oil separation efficiency.

Oil in the oil storage space (V3) may be supplied to the compression device3, and oil remaining after lubricating the compression device3and oil mixed with compressed refrigerant may be accumulated on an upper surface of the compression device3. As a result, the supply of oil to the compression device3may not be efficiently carried out in the oil storage space (V3) due to the shortage of oil, thereby causing damage to the compression device3or the rotational shaft5.

Accordingly, the oil accumulated on an upper surface of the compression device3should be guided to the oil storage space (V3) at a bottom portion thereof in order to supply oil to the compression device3. The recovery of oil to the oil storage space (V3) is very important to of the reliability of the compressor.

However, a wide oil discharge path should be provided to efficiently recover oil, but if the oil discharge path is too wide, then a fixed area for the casing of the main frame may decrease, deteriorating a fixing strength of the main frame. As a result, the oil discharge path should be formed to provide a sufficient fixed area.

