Semi-Hermetic Refrigerant Compressor

Abstract

In order to improve a semi-hermetic refrigerant compressor, comprising a reciprocating piston compressor, an electric motor, an overall housing which has a motor housing portion for the electric motor and a compressor housing portion for the reciprocating piston compressor, a suction-side refrigerant path which leads from a suction connection on the overall housing to an inlet chamber of the reciprocating piston compressor, and a pressure-side refrigerant path which leads from an outlet chamber of the reciprocating piston compressor to a pressure connection on the overall housing, such that the refrigerant compressor functions more efficiently, it is proposed that the electric motor is configured as a synchronous motor, in the rotor of which there are arranged permanent magnets for the synchronous operation of the electric motor and a squirrel cage for starting up the electric motor in asynchronous operation.

1 . A semi-hermetic refrigerant compressor, comprising a reciprocating piston compressor and an electric motor, an overall housing which has a motor housing portion for the electric motor and a compressor housing portion for the reciprocating piston compressor, a suction-side refrigerant path which leads from a suction connection on the overall housing to an inlet chamber of the reciprocating piston compressor, and a pressure-side refrigerant path which leads from an outlet chamber of the reciprocating piston compressor to a pressure connection on the overall housing, wherein at least one cylinder of the reciprocating piston compressor is provided in the compressor housing portion and has a piston movable in a cylinder bore formed in the compressor housing portion, a valve plate closing the cylinder bore, and a cylinder head extending over the valve plate and forming part of the compressor housing portion,
 the electric motor is configured as a synchronous motor, in the rotor of which there are arranged permanent magnets for the synchronous operation of the electric motor and a squirrel cage for the start-up of the electric motor in asynchronous operation.   
     
     
         2 . A refrigerant compressor according to  claim 1 , wherein the permanent magnets extend parallel to a rotor axis of the rotor. 
     
     
         3 . A refrigerant compressor according to  claim 2 , wherein the permanent magnets are formed as planar bodies, the flat sides of which extend in a longitudinal direction and in a transverse direction running transversely to the longitudinal direction. 
     
     
         4 . A refrigerant compressor according to  claim 1 , wherein the permanent magnets each extend with their longitudinal direction parallel to the rotor axis. 
     
     
         5 . A refrigerant compressor according to  claim 1 , wherein the permanent magnets extend with their transverse directions along outer edges of a geometric rectangle that is symmetrical with respect to the rotor axis. 
     
     
         6 . A refrigerant compressor according to  claim 1 , wherein the permanent magnets formed as planar bodies have a different magnetic polarity (N, S) on their mutually opposite flat sides, one of which faces towards the rotor axis and the other of which faces away from the rotor axis. 
     
     
         7 . A refrigerant compressor according to  claim 1 , wherein the suction-side refrigerant path passes through the motor housing for cooling of the electric motor. 
     
     
         8 . A semi-hermetic refrigerant compressor, comprising a reciprocating piston compressor and an electric motor, an overall housing which has a motor housing portion for the electric motor and a compressor housing portion for the reciprocating piston compressor, a suction-side refrigerant path which leads from a suction connection on the overall housing to an inlet chamber of the reciprocating piston compressor, and a pressure-side refrigerant path which leads from an outlet chamber of the reciprocating piston compressor to a pressure connection on the overall housing, wherein at least one cylinder of the reciprocating piston compressor is provided in the compressor housing portion and has a piston movable in a cylinder bore formed in the compressor housing portion, a valve plate closing the cylinder bore, and a cylinder head extending over the valve plate and forming part of the compressor housing portion, the refrigerant compressor is provided with an externally controlled mechanical capacity control unit. 
     
     
         9 . A semi-hermetic refrigerant compressor, comprising a reciprocating piston compressor and an electric motor, an overall housing which has a motor housing portion for the electric motor and a compressor housing portion for the reciprocating piston compressor, a suction-side refrigerant path which leads from a suction connection on the overall housing to an inlet chamber of the reciprocating piston compressor, and a pressure-side refrigerant path which leads from an outlet chamber of the reciprocating piston compressor to a pressure connection on the overall housing, wherein at least one cylinder of the reciprocating piston compressor is provided in the compressor housing portion and has a piston movable in a cylinder bore formed in the compressor housing portion, a valve plate closing the cylinder bore, and a cylinder head extending over the valve plate and forming part of the compressor housing portion, the mechanical capacity control unit for capacity reduction in at least one cylinder connects the outlet-side refrigerant path to the inlet-side refrigerant path. 
     
     
         10 . A refrigerant compressor according to  claim 9 , wherein the mechanical capacity control unit is arranged on the at least one cylinder head. 
     
     
         11 . A refrigerant compressor according to  claim 10 , wherein the mechanical capacity control unit is at least partially integrated in the at least one cylinder head. 
     
     
         12 . A refrigerant compressor according to  claim 9 , wherein the mechanical capacity control unit, for capacity reduction, connects an outlet chamber in the cylinder head to an inlet chamber in the cylinder head by means of a connection channel. 
     
     
         13 . A refrigerant compressor according to  claim 12 , wherein the connection channel is arranged integrated in the cylinder head. 
     
     
         14 . A refrigerant compressor according to  claim 1 , wherein the outlet chamber is arranged in the cylinder head directly adjacently to at least one outlet opening for the corresponding cylinder in the valve plate. 
     
     
         15 . A refrigerant compressor according to  claim 1 , wherein the inlet chamber is arranged in the cylinder head directly adjacently to an inlet opening for the corresponding cylinder in the valve plate. 
     
     
         16 . A refrigerant compressor according to  claim 9 , wherein the mechanical capacity control unit has a sealing piston for closing the connection channel. 
     
     
         17 . A refrigerant compressor according to  claim 16 , wherein the sealing piston, in order to close the connection channel, is placeable against a seal seat, which runs around the connection channel peripherally. 
     
     
         18 . A refrigerant compressor according to  claim 16 , wherein a seal region of the sealing piston is made of a metal having a lower hardness than a metal from which the seal seat is made. 
     
     
         19 . A refrigerant compressor according to  claim 17 , wherein the seal seat is arranged in a wall portion of the cylinder head separating the inlet chamber from the outlet chamber. 
     
     
         20 . A refrigerant compressor according to  claim 17 , wherein the seal seat is arranged in a wall portion running above the valve plate and above the inlet chamber. 
     
     
         21 . A refrigerant compressor according to  claim 17 , wherein the seal seat is arranged on the side of the inlet chamber opposite the valve plate. 
     
     
         22 . A refrigerant compressor according to  claim 17 , wherein starting from the seal seat, the stroke of the sealing piston ranges from a quarter to half of the mean diameter of the connection channel. 
     
     
         23 . A refrigerant compressor according to  claim 1 , wherein a cylinder head has an inlet chamber and an outlet chamber for a cylinder bank comprising at least two cylinders. 
     
     
         24 . A refrigerant compressor according to  claim 1 , wherein the mechanical capacity control unit is associated with a cylinder bank. 
     
     
         25 . A refrigerant compressor according to  claim 23 , wherein in the case of N cylinder banks of the refrigerant compressor a mechanical capacity control unit is associated with at least N−1 cylinder bank(s). 
     
     
         26 . A refrigerant compressor according to  claim 23 , wherein a mechanical capacity control unit is associated with each cylinder bank. 
     
     
         27 . A refrigerant compressor according to  claim 1 , wherein a check valve is provided in the compressor housing portion following on from the refrigerant paths that can be influenced by the mechanical capacity control unit. 
     
     
         28 . A refrigerant compressor according to  claim 27 , wherein the check valve has an outlet opening provided in the valve plate and a valve element cooperating with the valve plate. 
     
     
         29 . A refrigerant compressor according to  claim 28 , wherein the valve element is held on the valve plate. 
     
     
         30 . A refrigerant compressor according to  claim 16 , wherein the sealing piston in the direction of its position cooperating with the seal seat is acted on by a compression spring. 
     
     
         31 . A refrigerant compressor according to  claim 16 , wherein the sealing piston is actuable by a pressure chamber, which is actable on either by suction pressure or by high pressure depending on the external control of the capacity control unit. 
     
     
         32 . A refrigerant compressor according to  claim 31 , wherein the pressure chamber in the open position of the sealing piston has a volume that is less than a third, better still less than a quarter of the maximum volume of the pressure chamber in the closed position. 
     
     
         33 . A refrigerant compressor according to  claim 8 , wherein a control unit comprised by the capacity control unit is provided and is usable to control the pressure applied to the sealing piston. 
     
     
         34 . A refrigerant compressor according to  claim 8 , wherein a capacity controller is provided and controls the at least one mechanical capacity control unit in accordance with a required compressor delivery capacity. 
     
     
         35 . A refrigerant compressor according to  claim 1 , wherein a start-up control unit is provided and controls the start-up of the electric motor. 
     
     
         36 . A refrigerant compressor according to  claim 35 , wherein the start-up control unit operates the electric motor to start up with the windings connected in a manner reducing the start-up current. 
     
     
         37 . A refrigerant compressor according to  claim 35 , wherein the start-up control unit in order to start up the electric motor initially energizes a first part-winding and then energizes a second part-winding in a stator of the electric motor. 
     
     
         38 . A refrigerant compressor according to  claim 35 , wherein the start-up control unit controls the capacity controller at the start-up of the electric motor such that the reciprocating piston compressor operates only with reduced compressor delivery capacity at the start-up of the electric motor. 
     
     
         39 . A refrigerant compressor according to  claim 38 , wherein the start-up control unit controls the capacity controller in such a way that the reciprocating piston compressor works with the smallest possible compressor delivery capacity at the start-up of the electric motor. 
     
     
         40 . A refrigerant compressor according to  claim 1 , wherein the reciprocating piston compressor works with a suction pressure ranging from 10 bar to 50 bar. 
     
     
         41 . A refrigerant compressor according to  claim 1 , wherein the reciprocating piston compressor works with a high pressure ranging from 40 to 160 bar. 
     
     
         42 . A refrigerant compressor according to  claim 1 , wherein the reciprocating piston compressor works with carbon dioxide as refrigerant and in particular is configured for operation with carbon dioxide as refrigerant.