Electric brush lifter for wound-rotor three-phase asynchronous motor

Abstract

An electric brush lifting device for a wound-rotor three-phase asynchronous motor is characterized in that an insulating screw is symmetrically arranged on both sides of the short-circuit ring and the collector ring on the motor main shaft, one end of the brush holder is fixed on the insulating screw, and the carbon brush is installed on the other end of the brush holder; one end of the handle is fixedly connected to the insulating screw, and the other end is in contact with the outer edge of the cam through a rolling bearing; the cam is arranged in a box seat and connected to the transmission shaft and the output shaft of the reduction motor; one end of the crank handle is fixedly connected to the cam through a connecting rod, and the roller at the other end of the crank handle is installed in a groove on the outer side of the short-circuit ring; the end of the conductive screw on the collector ring is provided with an insert, and the insert is matched and connected with the short-circuit socket at the end of the short-circuit ring. The present invention has the characteristics of novel and simple structure, low manufacturing cost, reliable and stable performance, etc. In the continuous load operation stage of the motor, the carbon brush and the slip ring do not contact, thereby avoiding continuous wear of the electric carbon brush, and the carbon brush does not need to be replaced after the entire design life range of the motor.

Description

Technical Field

[0001] The invention relates to an electric motor, in particular to an electric brush lifting device for a winding-type three-phase asynchronous motor. Background Art

[0002] The three-phase wound-rotor asynchronous motor can reduce the starting current of the rotor and stator by connecting additional resistance in the rotor circuit through the collector ring and carbon brush. At the same time, as the rotor circuit resistance increases, the power factor of the rotor circuit increases, which can increase the starting torque of the motor accordingly. Therefore, the wound-rotor motor can be started directly under heavy load conditions and is widely used in heavy load equipment such as cement plants, mining metallurgy and lifting machinery.

[0003] After the three-phase wound-rotor asynchronous motor is started, the additional resistance in the rotor circuit needs to be gradually reduced, and finally the additional resistance in the rotor circuit is zero (i.e. the rotor three-phase coil is short-circuited), so that the motor can operate efficiently. This is usually achieved by a water resistance cabinet (liquid rheostat). Because the short-circuit point of the rotor circuit is within the water resistance cabinet (liquid rheostat), during the operation of the wound-rotor motor, the carbon brushes and slip rings must always maintain reliable contact to transmit the rotor current and prevent the rotor circuit from having three-phase imbalance or phase loss. During the continuous operation of the carbon brushes and slip rings, the carbon brushes are constantly worn and need to be stopped regularly for replacement. The working surface of the slip ring will also be worn or burned by electric sparks, and the smoothness will decrease, thereby accelerating the wear of the carbon brushes. The carbon fine powder produced by the wear of the carbon brushes adheres to the surface of the insulating material, which will reduce the insulation performance of the motor and cause various insulation failures in the motor, such as arcing between phases of the collector ring, breakdown to the ground, and burning of the carbon brushes. Therefore, the wound-rotor motor must be stopped regularly to clean the carbon powder in the collector ring to maintain the safe operation of the motor.

[0004] The brush lift device can short-circuit the collector ring and separate the carbon brush and collector ring after the motor is started. During the continuous load operation stage of the motor, the carbon brush and slip ring are not in contact, thereby avoiding the continuous wear of the electric carbon brush and the generation and adhesion of carbon fine powder, which will reduce the insulation performance. The carbon brush does not need to be replaced after the entire design life of the motor. However, due to the high manufacturing cost of the brush lift device and the low market acceptance, the winding motor with brush lift function has not been widely promoted and used. Summary of the invention

[0005] The object of the present invention is to provide an electric brush lifting device for a winding-type three-phase asynchronous motor with a simple structure, low manufacturing cost and reliable and stable performance.

[0006] The electric brush lifting device of the wound-rotor three-phase asynchronous motor of the present invention comprises a carbon brush, a short-circuit ring, a collector ring and a conductive screw, and is characterized in that an insulating screw is symmetrically arranged on both sides of the short-circuit ring and the collector ring on the motor main shaft, the insulating screw is fixed in the box seat through a bearing, one end of the brush holder is fixed on the insulating screw, and the carbon brush is installed at the other end of the brush holder, the brush holder and the carbon brush rotate together with the insulating screw, and the carbon brush can contact the outer side of the collector ring; one end of the rotating handle is fixedly connected to the insulating screw, and the other end contacts the outer edge of the cam through a rolling bearing, and the two ends of the tension spring are respectively fixed on the middle part of the rotating handle and the box seat, and the tension of the tension spring makes The rolling bearing at the end of the handle always keeps in contact with the end face of the cam; the cam is arranged in the box seat and above the short-circuit ring, the cam is connected to the transmission shaft, and the transmission shaft is connected to the output shaft of the reduction motor; the fulcrum of the crank handle is fixed on the box seat, one end of the crank handle is fixedly connected to the cam through a connecting rod, and the other end of the crank handle is provided with a roller, the roller is installed in the groove on the outer side of the short-circuit ring and contacts the end face of the groove, and the lever movement of the crank handle drives the short-circuit ring to move axially on the main shaft of the generator; the end of the conductive screw on the collector ring is provided with an insert, and the end of the short-circuit ring opposite to the insert on the conductive screw is provided with a short-circuit socket, and the short-circuit socket is connected with the insert.

[0007] The working principle of the electric brush lifting device of the wound-type three-phase asynchronous motor of the present invention is that before the wound-type three-phase asynchronous motor is started, the carbon brush is lifted and the plug of the collector ring remains inserted into the short-circuit socket. When the motor is started, the motor control system sends a start signal to the brush lifting device, the reduction motor starts to drive the cam to rotate, and the rolling bearing on the handle keeps in contact with the outer edge of the cam under the tension of the tension spring. When the cam rotates, the rotation radius of the roller bearing contact point gradually increases, the roller bearing is pressed downward, driving the handle and the brush holder to rotate downward, and the carbon brush gradually approaches the collector ring. When the cam rotates about 60° to the maximum radius, the carbon brush is pressed to the lowest position to keep in full contact with the collector ring. At the same time, when the cam rotates, the connecting rod drives the crank handle to push the short-circuit ring to the left through the roller bearing, and the short-circuit socket and the plug are gradually separated; when the cam rotates about 220°, the roller bearing at the lower end of the crank handle pushes the short-circuit ring to the farthest position from the collector ring. At this time, the cam continues to rotate, and the roller bearing at the lower end of the crank handle begins to move to the right and leave the leftmost side of the short-circuit ring groove. When the cam rotates 260 degrees, the travel switch triggers the stop signal, the reduction motor stops rotating, and the roller bearing remains in the middle position of the short-circuit ring groove, and no longer has any contact with the short-circuit ring. The short-circuit ring is separated from the collector ring, and the carbon brush remains in contact with the collector ring. The water resistance cabinet (liquid resistance cabinet) is connected in series to the motor rotor circuit. The travel switch sends a signal that the motor can be started to the motor control system. After receiving the signal, the system supplies power to the motor and starts the motor in the state of serial connection with the water resistance cabinet. When the motor starts and reaches the rated speed, the resistance value in the water resistance cabinet gradually decreases, and finally the three phases of the motor rotor are short-circuited in the water resistance cabinet. When the short circuit of the water resistance cabinet is completed, the motor control system sends an operation signal to the brush lifting device, and the reduction motor starts to drive the cam to rotate in the opposite direction. The connecting rod drives the crank handle to push the short-circuit ring and the short-circuit socket to gradually approach the plug-in through the roller bearing; when the cam is reversed by about 120°, the roller bearing at the lower end of the crank handle pushes the short-circuit ring and the short-circuit socket to start contacting the plug-in. When the cam is reversed by about 190°, the plug-in has been mostly inserted into the short-circuit socket, and the collector ring is already in a short-circuit state. After that, the contact point between the cam and the roller bearing The radius begins to decrease, and the carbon brush begins to separate from the collector ring. When the cam reverses about 220°, the roller bearing reaches the rightmost end of the stroke, the insertion depth of the collector ring plug and the short-circuit ring socket reaches the maximum, and the distance between the carbon brush and the collector ring is still gradually increasing. The roller bearing retreats to the left to the center of the short-circuit ring groove and no longer has any contact with the short-circuit ring; the travel switch triggers the stop signal, the reduction motor stops rotating, the collector ring plug and the short-circuit ring socket maintain the maximum insertion depth, and the carbon brush reaches the position with the maximum distance from the collector ring.

[0008] The electric brush lifting device for a wound-rotor three-phase asynchronous motor of the present invention has the characteristics of novel and simple structure, low manufacturing cost, reliable and stable performance, etc. During the continuous load operation stage of the motor, the carbon brush and the slip ring are not in contact, thereby avoiding continuous wear of the electric carbon brush, and the carbon brush does not need to be replaced after the entire design life range of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a structural schematic diagram of the present invention;

[0010] Figure 2 for Figure 1 A schematic side cross-sectional view of

[0011] Figure 3 for Figure 1 Another working state schematic diagram;

[0012] Figure 4 for Figure 1 Schematic diagram of the connection structure of the central rotating shaft, carbon brush, brush holder, rotating handle and cam;

[0013] 1. Box cover, 2. Box seat, 3. Cam, 4. Connecting rod, 5. Rocker, 6. Short-circuit ring, 7. Short-circuit socket, 8. Insert, 9. Collector ring, 10. Conductive screw, 11. Carbon brush, 12. Turning handle, 13. Roller, 14. Tension spring, 15. Brush holder, 16. Insulating screw, 17. Reducer motor, 18. Transmission shaft. DETAILED DESCRIPTION

[0014] A wound-rotor three-phase asynchronous motor electric brush lifting device, comprising a carbon brush 11, a short-circuit ring 6, a collector ring 9, and a conductive screw 10, characterized in that an insulating screw 16 is symmetrically arranged on both sides of the short-circuit ring 6 and the collector ring 9 on the motor main shaft, and the insulating screw 16 is fixed in the box seat 2 through a bearing, one end of a brush holder 15 is fixed on the insulating screw 16, and three brush holders 15 are fixed on each insulating screw 16, and a carbon brush 11 is installed at the other end of the brush holder 15, and the brush holder 15 and the carbon brush 11 rotate together with the insulating screw 16, and the carbon brush 11 can contact the outer side of the collector ring 9; one end of a rotating handle 12 is fixedly connected to the insulating screw 16, and the other end is connected to the insulating screw 16 through a rolling bearing. It contacts the outer edge of the cam 3, and the two ends of the tension spring 14 are respectively fixed on the middle of the handle 12 and the box seat 2; the cam 3 is arranged inside the box seat 2 and above the short-circuit ring 6, and the cam 3 is connected to the transmission shaft 18, and the transmission shaft 18 is connected to the output shaft of the reduction motor 17; the fulcrum of the crank 5 is fixed on the box seat 2, one end of the crank 5 is fixedly connected to the cam 3 through the connecting rod 4, and the other end of the crank 5 is provided with a roller 13, and the roller 13 is installed in the groove on the outer side of the short-circuit ring 6 and contacts the end face of the groove; the end of the conductive screw 10 on the collector ring 9 is provided with a plug 8, and the end of the short-circuit ring 6 opposite to the plug 8 on the conductive screw 10 is provided with a short-circuit socket 7, and the short-circuit socket 7 is connected with the plug 8.

Claims

1. An electric brush lifting device for a wound-rotor three-phase asynchronous motor, comprising a carbon brush (11), a short-circuit ring (6), a collector ring (9), and a conductive screw (10), characterized in that: An insulating screw (16) is symmetrically arranged on both sides of the short-circuit ring (6) and the collector ring (9) on the main shaft of the motor. One end of the brush holder (15) is fixed on the insulating screw (16). The carbon brush (11) is installed on the other end of the brush holder (15). The brush holder (15) and the carbon brush (11) rotate together with the insulating screw (16). The carbon brush (11) can contact the outer side surface of the collector ring (9). One end of the rotating handle (12) is fixedly connected to the insulating screw (16), and the other end is in contact with the outer edge of the cam (3) through a rolling bearing. The cam (3) is arranged in the box seat (2) and above the short-circuit ring (6). The cam (3) is connected to the transmission shaft (18), and the transmission shaft (18) is connected to the output shaft of the reduction motor (17); the fulcrum of the crank handle (5) The invention is fixed on the box seat (2), one end of the crank handle (5) is fixedly connected to the cam (3) through a connecting rod (4), and the other end of the crank handle (5) is provided with a roller (13), which is installed in a groove on the outer side of the short-circuit ring (6) and contacts the end surface of the groove; the end of the conductive screw (10) on the collector ring (9) is provided with an insert (8), and the end of the short-circuit ring (6) opposite to the insert (8) on the conductive screw (10) is provided with a short-circuit socket (7), and the short-circuit socket (7) is connected with the insert (8); the insulating screw (16) is fixed in the box seat (2) through a bearing; three brush holders (15) are fixed on each insulating screw (16); and the two ends of the tension spring (14) are respectively fixed to the middle of the handle (12) and the box seat (2).

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