Displacement type compressor having a self-start synchronous motor and start load reducing means

#The present invention relates to a displacement type compressor which deals with a refrigerant, air, carbon dioxide and the other compression gases, and is particularly preferable for a displacement type compressor which is driven by a self-start synchronous motor which starts as an induction motor and performs synchronous operation by performing synchronization pull-in almost at a synchronous rotational frequency.

#As one of motors having high energy efficiency, there is a self-start synchronous motor. In displacement type compressors represented by a scroll compressor, a screw compressor, a reciprocating compressor, a rotary compressor and the like, it becomes necessary to improve energy efficiency of a driving motor to improve its energy efficiency, and research and development of the displacement type compressor having the high energy efficiency using the self-start synchronous motor are made increasingly.

#As a prior art relating to a displacement type compressor using a self-start synchronous motor, there is a refrigerating apparatus shown in JP-A-2003-35289. The refrigerating apparatus disclosed in JP-A-2003-35289 includes a compressor which is driven by a self-start synchronous motor, a condenser and an evaporator. The self-start synchronous motor is provided with a winding wire which is wound around an iron core of its rotor so as to operate as an induction-motor, and a permanent magnet which is magnetized to the iron core of the rotor in the same way so as to operate as a synchronous motor, and is driven as an induction motor at startup and as a synchronous motor at a time of steady state operation. A refrigerant gas is compressed in a compression chamber which is constructed by a fixed scroll and a rotary scroll, and is discharged through the inside of a compression container out of the compressor. The refrigerating apparatus is provided with a bypass circuit which establishes a bypass between a discharge side and an inlet side of the compressor so as to bypass the discharge side and the inlet side before starting.

#FIG. 1 is a vertical sectional view of a scroll compressor of a first embodiment of the present invention;

#FIG. 2 is a sectional view taken along line A-A in FIG. 1;

#FIG. 3 is a diagram showing schematic relation between torque and rotational frequency of a self-start synchronous motor in the scroll compressor of the first embodiment;

#A plurality of embodiments of the present invention will be described hereinafter with use of the drawings. The same reference numerals in the drawings of the respective embodiments show the same components or the equivalents.

#A scroll compressor of a first embodiment of the present invention will be described in detail by using FIGS. 1 to 3.

#First, the entire construction of the scroll compressor will be described by using FIG. 1. FIG. 1 is a vertical sectional view of the scroll compressor of this embodiment. The scroll compressor of this embodiment is constructed to include a self-start synchronous motor 5 which starts as an induction motor and performs synchronous operation by performing synchronization pull-in almost at a synchronous rotational frequency, a compression part having a compression chamber 11 which compresses a working fluid, a hermetic container 4 which houses the self-start synchronous motor 5 and the compression part, and a start load reducing means 21 which reduces the load of the compression part at startup.