Cooling fan and air-cooled refrigerator comprising same

Abstract

A cooling fan and an air-cooled refrigerator are provided. The cooling fan includes a synchronous motor and an impeller. The synchronous motor includes a stator and a permanent magnetic rotor. The permanent magnetic rotor includes a rotary shaft and a permanent magnetic rotor main body attached around the rotary shaft. The stator includes a stator core and a stator winding wound around the stator core and powered by an alternating-current power supply. The permanent magnetic rotor operates at a constant rotational speed of 60f/p during a steady state operation of the motor, where f is a frequency of the AC power source and p is the number of pole pairs of the permanent magnet poles. The impeller is connected to the rotary shaft for rotation under the driving of the rotary shaft.

1 . A cooling fan comprising:
 a synchronous motor, comprising:
 a stator comprising a stator core and a stator winding wound around the stator core and powered by an alternating-current power supply; and 
 a permanent magnetic rotor rotatable relative to the stator, the permanent magnetic rotor including a rotary shaft and a rotor main body with permanent magnetic poles attached around the rotary shaft; and 
   an impeller connected to the rotary shaft for rotation under the driving of the rotary shaft,   wherein the permanent magnetic rotor operates at a constant rotational speed during a steady state operation of the motor.   
     
     
         2 . The cooling fan of  claim 1 , wherein one of the rotor main body and the impeller is in rigid connection with the rotary shaft for synchronous rotation with the rotary shaft, the other one is in soft connection with the rotary shaft to enable relative rotation therebetween, and a delay synchronization device is connected between the other one and the rotary shaft in order to gradually achieve synchronous rotation therebetween. 
     
     
         3 . The cooling fan of  claim 2 , wherein the delay synchronization device includes a mounting seat and a buffering mechanism, the mounting seat is fixedly connected to the rotary shaft, one end of the buffering mechanism is connected to the mounting seat, and the other end of the buffering mechanism is connected to the rotor main body or the impeller which is in sliding connection with the rotary shaft. 
     
     
         4 . The cooling fan of  claim 1 , wherein the impeller comprises a mounting portion for mounting to the rotary shaft, the mounting portion is in sliding fit with the rotary shaft; the cooling fan further comprises a delay synchronization device including a mounting seat and a buffering mechanism, two ends of the buffering mechanism are connected to the mounting seat and the mounting portion, respectively, to synchronize the mounting seat and the mounting portion in rotation speed in a delayed manner. 
     
     
         5 . The cooling fan of  claim 4 , wherein the buffering mechanism is an elastic member that is attached around the rotary shaft and is variable in inner and outer diameters. 
     
     
         6 . The cooling fan of  claim 5 , wherein the elastic member is a helical spring. 
     
     
         7 . The cooling fan of  claim 4 , wherein the delay synchronization device further includes a protective sleeve surrounding an outer periphery of the elastic member. 
     
     
         8 . The cooling fan of  claim 7 , wherein one end of the protective sleeve is fixed on the mounting portion, and the other end of the protective sleeve is movably sleeved around the mounting seat. 
     
     
         9 . The cooling fan of  claim 1 , wherein the stator core includes a yoke and two salient poles protruding inwards respectively from two opposing inner surfaces of the yoke, each salient pole includes a winding portion for mounting the stator winding and arcuate pole shoes extending from an inner radial side towards two circumferential sides of the winding portion, and the permanent magnetic rotor is accommodated in a cavity cooperatively defined by the pole shoes. 
     
     
         10 . The cooling fan of  claim 9 , wherein an outer radial end of each of the salient poles and the inner surface of the yoke are provided with an interlocking structure for connecting the salient pole and the yoke. 
     
     
         11 . The cooling fan of  claim 9 , wherein an outer surface of each of the permanent magnet poles of the permanent magnetic rotor is an arc surface, an air gap with uneven thickness is formed between the outer surface of each permanent magnet pole and an inner surface of a corresponding pole shoe, and the air gap is symmetric with respect to a center line of the respective salient pole. 
     
     
         12 . The cooling fan of  claim 11 , wherein a magnetic bridge or slot opening with a large magnetic reluctance exists between the pole shoes of the two salient poles, and the thickness of the air gap is maximum at the magnetic bridge or slot opening and gradually decreases along directions away from the magnetic bridge or slot opening. 
     
     
         13 . The cooling fan of  claim 1 , wherein the cooling fan further includes a drive circuit, the stator winding and the external alternating-current power supply are connected in series between a first node and a second node, the drive circuit includes a controllable bidirectional alternating-current switch, an alternating-current to direct-current conversion circuit connected with the bidirectional alternating-current switch in parallel between the first and second nodes, a position sensor, and a switch control circuit, when the controllable bidirectional alternating-current switch is switched on, the alternating-current to direct-current conversion circuit has no current flowing therethrough because the first node and the second node are shorted, the switch control circuit is configured to control the controllable bidirectional alternating-current switch to switch between ON and OFF states of a positive or negative half-wave cycle in a predetermined manner according to rotor magnet pole position information detected by the position sensor and polarity information of the external alternating-current power supply, such that the stator winding drives the rotor to rotate only along a predetermined startup direction in a motor startup stage. 
     
     
         14 . The cooling fan of  claim 9 , wherein the stator further includes a housing, the inner surface of the housing includes an annular closed step for supporting an axial end face of the yoke, and a plurality of bumps for abutting against an outer surface of the yoke. 
     
     
         15 . The cooling fan of  claim 1 , wherein the synchronous motor is a single-phase motor and the permanent magnetic rotor operates at the constant rotational speed of 60f/p during the steady state operation of the motor, where f is a frequency of the alternating-current power supply and p is the number of pole pairs of the permanent magnet poles. 
     
     
         16 . The cooling fan of  claim 15 , wherein an input power for the motor is set between 2W and 5W and a current is set between 0.08 A and 0.12 A. 
     
     
         17 . An air-cooled refrigerator comprising:
 an accommodating cavity with a condenser tube; and   a cooling fan of  claim 1  accommodated in the accommodating cavity for cooling the condenser tube.