External motor cooling system of permanent-magnet direct-drive medium-speed coal mill
By introducing an external lubricating oil cooling system into the permanent magnet direct-drive medium-speed coal mill, the problem of bearing temperature rise was solved, and continuous circulation cooling of lubricating oil was achieved, thereby improving the reliability and operational stability of the equipment.
Patent Information
- Application Number
- CN202520288636.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-21
- Publication Date
- 2025-11-04
- Estimated Expiration
- 2035-02-21
AI Technical Summary
The bearing temperature of the permanent magnet direct drive medium-speed coal mill rises, especially in high-temperature environments where the oil temperature self-cools slowly, leading to frequent high bearing temperature alarms and posing a risk of oil failure due to high temperature during long-term operation.
An external lubricating oil cooling system was designed, including a thrust bearing oil trough, an oil sump, and an external lubricating oil cooling system. The system is connected to a cooler through an oil drain hole and an oil filling hole. The system utilizes an independent oil pump and an electric motor to achieve circulating cooling of the lubricating oil. A tubular cooler is used to remove heat. The system is combined with a level gauge and valves for real-time monitoring and maintenance.
It effectively reduced bearing temperature, decreased equipment downtime for maintenance, improved equipment reliability and operational stability, and prevented oil failure due to high temperatures.
Smart Images
Figure CN223511353U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to motor cooling technical field, more exactly, it relates to a kind of external motor cooling system of permanent magnet direct drive medium speed coal mill. BACKGROUND
[0002] Permanent magnet speed regulation is the transmission technology of torque transmission through air gap, it is based on modern magnetism as basic theory, the air gap or coupling area between permanent magnet and conductor is adjusted, the output torque of load end is changed, so that the change of load end rotating speed is realized, and the continuous control of flow is achieved.
[0003] The feature is that mechanical connection is not needed between motor and load shaft, when motor drives conductor disc to rotate, strong magnetic field generated by cutting permanent magnet disc, and then eddy current is generated in conductor disc and reverse induction magnetic field is established, forming magnetic torque. Since the torque output to conductor disc by motor is equal to the torque output to load end by permanent magnet disc, when permanent magnet speed regulation mechanism receives a speed regulation instruction, the size of air gap or meshing surface adjustment mode between conductor disc and permanent magnet disc is adjusted, the torque is changed, so that the change of load rotating speed is realized.
[0004] The conventional coal mill of large-scale thermal power generator set is motor + speed reducer + coal mill structure, in recent years, with the gradual development of frequency conversion speed regulation device and permanent magnet speed regulation device, it has become one of the effective measures to save cost. Large-scale thermal power generator set coal mill uses permanent magnet direct drive medium speed coal mill, which has been applied in individual power plants. The magnetic force coupling device of permanent magnet speed regulation replaces the conventional rigid coupling, so that there is no mechanical connection between motor and load, and the vibration on both sides will not be transmitted. It has been proved that, after using permanent magnet speed regulation device, the vibration can be reduced by about 80%. The difficulty of fault finding is easy, the number of fault points is small, and the required personnel is low. Only bench worker needs to maintain permanent magnet mechanical equipment, the operation is simple, and the operation and maintenance cost is small.
[0005] When permanent magnet direct drive medium speed coal mill starts, the air gap is adjusted to the maximum to realize no-load start, which can greatly reduce motor starting current and starting time. When motor reaches rated rotating speed, the load is started smoothly by adjusting air gap, and starting current is reduced.
[0006] The permanent magnet motor of permanent magnet direct drive medium speed coal mill is composed of bottom support bearing, middle guide bearing and upper sliding bearing, and the permanent magnet motor is of integrated structure, and each bearing is self-lubricated by oil bath. In actual operation, the temperature of bearing of permanent magnet direct drive medium speed coal mill is increased, and the temperature is close to alarm temperature, especially in summer environment with high temperature, the oil temperature is slowly cooled, the oil temperature is high, the motor bearing temperature high alarm condition frequently occurs, and there is a risk of oil quality high-temperature failure in long-time operation. UTILITY MODEL CONTENTS
[0007] The purpose of this utility model is to address the shortcomings of existing technologies by proposing an external motor cooling system for a permanent magnet direct-drive medium-speed coal mill, comprising:
[0008] Thrust bearing oil sump, oil bath, and external lubricating oil cooling system;
[0009] The thrust bearing oil groove and the oil sump are both connected to the external lubricating oil cooling system. The thrust bearing oil groove and the oil sump are provided with oil drain holes and oil filling holes. The lubricating oil in the thrust bearing oil groove and the oil sump is drawn out from the oil drain holes, cooled by the external lubricating oil cooling system, and then returned to the thrust bearing oil groove and the oil sump through the oil filling holes.
[0010] Preferably, the external lubricating oil cooling system includes a first cooler, a first motor, a first oil pump, a cooling water inlet pipe, a first cooling water return pipe, a second cooling water return pipe, an oil sump, a second cooler, a second motor, and a second oil pump.
[0011] The thrust bearing oil sump has an oil drain hole connected to the first cooler, which is connected to the oil filler hole of the thrust bearing oil sump via a first oil pump. The first oil pump is connected to the first motor. The first cooler is connected to a cooling water inlet pipe and a first cooling water return pipe. The end of the first cooling water return pipe away from the first cooler is connected to a second cooler, which is also connected to a second cooling water return pipe. The oil drain hole of the oil sump is connected to the second cooler, which is connected to the oil filler hole of the oil sump via a second oil pump. The second oil pump is connected to the second motor.
[0012] Preferably, a level gauge is installed between the oil drain hole and the oil filling hole of the thrust bearing oil groove.
[0013] Preferably, a first filter is provided between the first cooler and the oil drain hole of the thrust bearing oil tank; a second filter is provided between the second cooler and the oil drain hole of the oil sump.
[0014] Preferably, a first valve is provided between the oil filling hole of the thrust bearing oil tank and the first oil pump, and a second valve is provided between the oil filling hole of the oil sump and the second oil pump.
[0015] The beneficial effects of this utility model are:
[0016] 1. This utility model features an external lubricating oil cooling system installed through an oil filling hole and an oil drain hole. A separate oil pump draws lubricating oil directly from the drain hole, cools it in a cooler, and then pumps it back to the bearing oil chamber through the oil filling hole. The cooler is a tubular type; heat is carried away by cooling water, and the lubricating oil, after being cooled by the cooler, is returned to the machine body, achieving continuous circulating cooling.
[0017] 2. This utility model uses a level gauge to monitor the oil level in real time and combines it with valves to enable non-stop maintenance operations, significantly reducing equipment downtime for maintenance.
[0018] 3. This utility model removes impurities from lubricating oil through a filter, which can prevent impurities from entering the oil circuit and causing equipment wear. Attached Figure Description
[0019] Figure 1 A schematic diagram of the structure of an external motor cooling system for a permanent magnet direct-drive medium-speed coal mill provided by this utility model;
[0020] Explanation of reference numerals in the attached drawings: 1. Thrust bearing oil tank; 2. First cooler; 3. First motor; 4. First oil pump; 5. Cooling water inlet pipe; 6. First cooling water return pipe; 7. Second cooling water return pipe; 8. Oil sump; 9. Second cooler; 10. Second motor; 11. Second oil pump; 12. First valve; 13. First filter; 14. Second filter; 15. Level gauge; 16. Second valve. Detailed Implementation
[0021] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that, for those skilled in the art, several modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
[0022] As one example, such as Figure 1 As shown, this application provides an external motor cooling system for a permanent magnet direct-drive medium-speed coal mill, which replaces the conventional oil bath lubrication of the permanent magnet direct-drive medium-speed coal mill with an external cooling system, thereby reducing the lubricating oil temperature and improving the reliability of the permanent magnet direct-drive medium-speed coal mill.
[0023] Specifically, the external motor cooling system of this permanent magnet direct-drive medium-speed coal mill includes:
[0024] Thrust bearing oil sump 1, oil tank 8, and external lubricating oil cooling system;
[0025] The thrust bearing oil groove 1 and the oil sump 8 are both connected to the external lubricating oil cooling system. The oil sump 8 is a sliding bearing oil sump. Both the thrust bearing oil groove 1 and the oil sump 8 are provided with oil drain holes and oil filling holes. The lubricating oil in the thrust bearing oil groove 1 and the oil sump 8 is drawn out from the oil drain holes, cooled by the external lubricating oil cooling system, and then returned to the thrust bearing oil groove 1 and the oil sump 8 through the oil filling holes.
[0026] The external lubricating oil cooling system includes a first cooler 2, a first electric motor 3, a first oil pump 4, a cooling water inlet pipe 5, a first cooling water return pipe 6, a second cooling water return pipe 7, an oil sump 8, a second cooler 9, a second electric motor 10, and a second oil pump 11.
[0027] The oil drain hole of the thrust bearing oil sump 1 is connected to the first cooler 2, and the first cooler 2 is connected to the oil filling hole of the thrust bearing oil sump 1 via the first oil pump 4; the first oil pump 4 is connected to the first motor 3; the first cooler 2 is connected to a cooling water inlet pipe 5 and a first cooling water return pipe 6; the end of the first cooling water return pipe 6 away from the first cooler 2 is connected to a second cooler 9, and the second cooler 9 is also connected to a second cooling water return pipe 7; the oil drain hole of the oil sump 8 is connected to the second cooler 9, and the second cooler 9 is connected to the oil filling hole of the oil sump 8 via the second oil pump 11; the second oil pump 11 is connected to the second motor 10.
[0028] A level gauge 15 is installed between the oil drain hole and the oil filling hole of the thrust bearing oil tank 1.
[0029] A first filter 13 is provided between the first cooler 2 and the oil drain hole of the thrust bearing oil tank 1; a second filter 14 is provided between the second cooler 9 and the oil drain hole of the oil sump 8.
[0030] A first valve 12 is provided between the oil filling hole of the thrust bearing oil tank 1 and the first oil pump 4, and a second valve 16 is provided between the oil filling hole of the oil sump 8 and the second oil pump 11.
[0031] Currently, the modified motor's lower thrust bearing and upper sliding bearing have no longer experienced overheating, improving the reliability of the permanent magnet direct drive medium-speed coal mill and making its subsequent promotion possible.
[0032] In summary, this application utilizes an external lubricating oil cooling system installed through an oil filler hole and an oil drain hole. A separate oil pump draws lubricating oil directly from the oil drain hole, cools it in a cooler, and then pumps it back to the bearing oil chamber through the oil filler hole. The cooler is a tubular type; heat is carried away by cooling water, and the lubricating oil, after being cooled by the cooler, is returned to the machine body, achieving continuous circulating cooling.
Claims
1. An external motor cooling system for a permanent magnet direct-drive medium-speed coal mill, characterized in that, include: Thrust bearing oil groove (1), oil sump (8) and external lubricating oil cooling system; The thrust bearing oil groove (1) and the oil sump (8) are both connected to the external lubricating oil cooling system. The thrust bearing oil groove (1) and the oil sump (8) are provided with oil drain holes and oil filling holes. The lubricating oil in the thrust bearing oil groove (1) and the oil sump (8) is drawn out from the oil drain hole and cooled by the external lubricating oil cooling system before being returned to the thrust bearing oil groove (1) and the oil sump (8) through the oil filling hole.
2. The external motor cooling system for a permanent magnet direct-drive medium-speed coal mill according to claim 1, characterized in that, The external lubricating oil cooling system includes a first cooler (2), a first motor (3), a first oil pump (4), a cooling water inlet pipe (5), a first cooling water return pipe (6), a second cooling water return pipe (7), an oil sump (8), a second cooler (9), a second motor (10), and a second oil pump (11). The oil drain hole of the thrust bearing oil tank (1) is connected to the first cooler (2), and the first cooler (2) is connected to the oil filling hole of the thrust bearing oil tank (1) through the first oil pump (4); the first oil pump (4) is connected to the first motor (3); the first cooler (2) is connected to a cooling water inlet pipe (5) and a first cooling water return pipe (6); the end of the first cooling water return pipe (6) away from the first cooler (2) is connected to the second cooler (9), and the second cooler (9) is also connected to the second cooling water return pipe (7); the oil drain hole of the oil sump (8) is connected to the second cooler (9), and the second cooler (9) is connected to the oil filling hole of the oil sump (8) through the second oil pump (11); the second oil pump (11) is connected to the second motor (10).
3. The external motor cooling system for a permanent magnet direct-drive medium-speed coal mill according to claim 2, characterized in that, A level gauge (15) is installed between the drain hole and the fill hole of the thrust bearing oil groove (1).
4. The external motor cooling system for a permanent magnet direct-drive medium-speed coal mill according to claim 3, characterized in that, A first filter (13) is provided between the first cooler (2) and the oil drain hole of the thrust bearing oil tank (1); a second filter (14) is provided between the second cooler (9) and the oil drain hole of the oil sump (8).
5. The external motor cooling system for a permanent magnet direct-drive medium-speed coal mill according to claim 4, characterized in that, A first valve (12) is provided between the oil filling hole of the thrust bearing oil tank (1) and the first oil pump (4), and a second valve (16) is provided between the oil filling hole of the oil sump (8) and the second oil pump (11).