Cooling device for motor bearing

Abstract

The utility model discloses a cooling device for a motor bearing, which comprises a rotor, a load end bearing, a bearing fan, an annular air duct and a locking mounting lantern ring, the locking installation lantern ring is connected to the rotor in a sleeving mode and fixed, the bearing fan is connected with the locking installation lantern ring and connected to the rotor through the locking installation lantern ring, and the annular air guide cylinder is installed on the outer side of the bearing fan and guides air flow generated by the bearing fan to a bearing outer cover of the load end bearing and a motor end cover. And the annular air duct is connected with the motor end cover through an air duct stud. According to the utility model, the working temperature of the load end bearing can be effectively reduced, the safety and reliability of motor operation are ensured, field debugging and installation can be realized, and the motor does not need to be returned to a factory for maintenance.

Description

Technical Field

[0001] This utility model relates to the field of motor bearings, specifically to a cooling device for motor bearings. Background Technology

[0002] Bearings are key components of motors, supporting the rotating rotor and serving as crucial components for the transition between static and dynamic states. There are two main types of bearings used in motors: sliding bearings and rolling bearings. There are no strict limitations on the specific type of bearing to choose. Based on bearing performance, rolling bearings are mostly used in small motors with light loads and low speeds, while sliding bearings are mostly used in large motors with high speeds and heavy loads. Figure 1 The motor shown uses rolling bearings. The operating temperature of rolling bearings is mainly determined by factors such as bearing load, speed, and ambient temperature. Usually, the operating temperature of rolling bearings should not exceed 90℃. Excessive bearing temperature will cause the inner and outer rings of the rolling bearing to seize and be damaged, leading to motor failure and shutdown. When the motor is running, the operating temperature of the rolling bearings must be monitored. It is usually set to alarm above 90℃ and shut down above 95℃ to avoid accidents. Figure 1 The method used to cool the bearings is as follows: the inner fan 1 is mounted and fixed on the rotor 2, and the rotor 2 drives the inner fan 3 to rotate. The air inside the drive motor circulates along the air passage 6 in the cooler 4, thereby removing heat. When the inner fan 3 is mounted on the rotor 2, it adopts a small interference fit and is equipped with a key 7 to transmit the torque required for the rotation of the inner fan 3.

[0003] Currently, motors using this design suffer from poor heat dissipation, insufficient bearing cooling, and excessively high operating temperatures. For example, some 450-560KW motors used to drive vertical coal mills in thermal power plants experience excessively high operating temperatures in their load-side rolling bearings, all exceeding 80℃. During the high temperatures of summer, these bearings frequently trigger temperature alarms, affecting the safe operation of the coal mill and consequently impacting the safe production of the power plant. Field investigations revealed two main reasons for the high temperature of the motor's load-side rolling bearings: firstly, the surface temperature of the vertical coal mill casing is high, exceeding 150℃, leading to heat radiation to the load-side bearings; secondly, the load-side bearings are located in the high-temperature zone of the motor's internal circulating air, thus influencing their operating temperature. Furthermore, since the motors are already in operation and cannot be returned to the manufacturer for repair, the primary objective for technical personnel is to address the technical challenges of excessively high operating temperatures in the load-side rolling bearings based on the on-site operating conditions. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a cooling device for motor bearings that can reduce the operating temperature of the bearing at the load end and can be installed and debugged on-site.

[0005] One technical solution to achieve the above objective is: a cooling device for motor bearings, comprising a rotor and a load-end bearing, characterized in that: it further comprises a bearing fan, an annular air guide tube, and a locking mounting collar;

[0006] The locking mounting collar is fitted onto and fixed to the rotor. The bearing fan is connected to the locking mounting collar and is connected to the rotor through the locking mounting collar. The annular air guide is installed on the outside of the bearing fan to guide the airflow generated by the bearing fan to the bearing cover of the load end bearing and the motor end cover. The annular air guide is connected to the motor end cover through the air guide stud.

[0007] Furthermore, the locking and mounting collar is a ring structure with an axial groove along the axial direction and a radial groove along the radial direction. The axial groove and the radial groove are intersected. The locking and mounting collar has a collar bolt hole perpendicular to the axial groove. When the locking and mounting collar is fitted onto the rotor, the inner diameter of the locking and mounting collar is changed by inserting a collar bolt into the collar bolt hole.

[0008] Furthermore, the radial groove is symmetrical about the axial groove, with a width of 3mm for the radial groove and a width of 2mm for the axial groove.

[0009] Furthermore, a bearing fan connection hole is provided on the end face of the locking mounting collar, and the bearing fan is connected and fixed to the locking mounting collar by a fan fixing bolt.

[0010] Furthermore, the bearing fan is an axial flow fan.

[0011] Furthermore, the hub ratio of the axial fan is less than 0.5, and the blade length of the axial fan is at least 100mm.

[0012] Furthermore, the axial fan is a plastic fan with an adjustable blade mounting angle.

[0013] Furthermore, the axial distance L between the annular air guide tube and the motor end cover is adjusted and controlled by the length of the air guide tube stud, with L being 30–50 mm.

[0014] Furthermore, the mating surface of the locking mounting collar facing the motor end cover is provided with a dynamic sealing snap-fit ​​structure, which, together with the motor end cover, forms a curved dynamic sealing structure. The radial mating clearance between the two is 0.5 mm, and the axial mating length is 5 mm.

[0015] This invention discloses a cooling device for motor bearings. Practical testing has proven its effectiveness, demonstrating that it can effectively reduce the operating temperature of the bearing at the load end, with an average temperature reduction of over 15K. Furthermore, this invention allows for on-site modification of the motor, with a convenient and efficient modification process that eliminates the need for factory repairs, thus reducing maintenance costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an existing motor bearing cooling structure;

[0017] Figure 2 This is a schematic diagram of the load end of an existing motor bearing.

[0018] Figure 3 This is a schematic diagram of the cooling device for motor bearings according to the present invention.

[0019] Figure 4 for Figure 3 Cross-sectional view along the AA direction;

[0020] Figure 5 for Figure 3 A magnified view of the details of part I;

[0021] Figure 6 This is a schematic diagram of the locking mounting sleeve of this utility model;

[0022] Figure 7 for Figure 6 Sectional view in the BB direction;

[0023] Figure 8 This is a top view of the locking mounting sleeve of this utility model;

[0024] Figure 9 This is a schematic diagram of the airflow path if a centrifugal fan is used as the bearing fan. Detailed Implementation

[0025] To better understand the technical solution of this utility model, a detailed description is provided below through specific embodiments:

[0026] The present invention relates to a cooling device for motor bearings, which aims to add a bearing fan at the load end bearing to blow flowing cool air onto the surface of the bearing device, thereby improving the surface heat dissipation effect and reducing the bearing temperature.

[0027] Please see Figure 2 During on-site handling, the labyrinth ring 51 and bearing cover 52 of the original load-end bearing assembly need to be removed. Then, as follows... Figures 3 to 4 Install bearing fan 9.

[0028] Normally, the installation of bearing fan 9 should be as follows: Figure 1 The internal fan 3 is installed in the same way, with a small interference fit to the rotor 2 and a keyed structure. However, since the motor is currently running at the user's site, there are no conditions for machining the keyway on the rotor 2 on-site, nor are there conditions for heat-fitting the fan.

[0029] Therefore, in this utility model, a locking mounting collar 10 was developed, which is used to mount the bearing fan 9 onto the rotor.

[0030] Please see Figures 6 to 8 The locking mounting collar 10 is an annular structure with an axial groove 101 along its axial direction to completely cut off the upper half of the locking mounting collar 10, and a radial groove 102 along its radial direction to divide the locking mounting collar 10 into two parts along its axial direction. The axial groove and the radial groove are staggered, and the radial groove 102 is symmetrical about the axial groove 101. The width of the radial groove 102 is 3mm, and the width of the axial groove 101 is 2mm. A set of two collar bolt holes 103, which are M12 threaded holes, are provided on the locking mounting collar 10 perpendicular to the axial groove 101 for installing collar bolts. Seven bearing fan connection holes 104 are provided on the end face of the locking mounting collar 10, and the bearing fan 9 is connected and fixed to the locking mounting collar 10 by fan fixing bolts.

[0031] Please see Figure 3 and Figure 4 The inner diameter tolerance of the locking mounting collar 10 (150R8) is slightly larger than the outer diameter (150d7) of the rotor 2. During installation, the locking mounting collar 10 is fitted onto the load end of the rotor 2, and its axial position is adjusted to match the mounting position of the bearing fan 9. Then, the collar bolts 15 are tightened. At this time, the inner diameter of the locking mounting collar 10 deforms, and the inner diameter (150R8) becomes smaller, firmly fixing the locking mounting collar 10 to the rotor 2. The bearing fan 9 is then installed on the locking mounting collar 10 using seven fan fixing bolts 11, thus fixing the bearing fan 9 to the rotor 2. After installation, the collar bolts 15 are spot-welded to the locking mounting collar 10 to prevent loosening.

[0032] For bearing fan 9, either an axial fan or a centrifugal fan can be selected. Considering that the cool air blown by bearing fan 9 should be directed as close as possible to the center of the bearing assembly, the closer to the heat-generating parts of the bearing, the better the heat dissipation effect. Figure 9 If a centrifugal fan is selected, the airflow generated can only be blown onto the motor end cover 14 after being guided by the air guide shroud, and the heat dissipation effect is not very good. After comparative analysis, an axial fan was finally selected.

[0033] The axial fan 9 was specially designed according to requirements. The fan design hub ratio is less than 0.5. Under the premise of meeting the structural design requirements, the hub diameter d is minimized as much as possible, the outer diameter D of the fan is increased, and the blade length is lengthened (>100mm). This allows the impeller to blow out cold air to the surface of the bearing device as parallel as possible over a large area, thereby improving the heat dissipation effect.

[0034] The axial fan 9 uses a plastic fan with an adjustable blade mounting angle. The plastic fan reduces impeller weight, thereby reducing the torque required for rotation and the pressure of on-site installation. The adjustable blade mounting angle allows for adjustment of the required airflow according to site conditions to meet specific needs.

[0035] The fitting clearance δ between the axial fan 9 and the annular air guide 8 is typically taken as δ = 0.008~0.01S, where S is the blade length. Too large a clearance will cause airflow loss, while too small a clearance will increase the difficulty of manufacturing. Considering the actual on-site installation conditions and the difficulty in controlling the dimensions, the fitting clearance is appropriately increased, and the final design value for this fitting clearance is 5mm.

[0036] like Figure 3 As shown, the airflow generated by the axial fan 9 first flows axially, blowing towards the surfaces of the bearing outer cover 13 and the motor end cover 14, and then flows radially along the surface of the motor end cover 14, carrying away the generated heat. Therefore, the axial installation distance L between the annular air guide duct 8 and the motor end cover 14 is an important consideration. If L is too small, the airflow resistance will be large, resulting in a reduction in airflow; if L is too large, it will reduce the airflow velocity on the surfaces of the bearing outer cover 13 and the motor end cover 14, both of which will reduce the heat dissipation effect. Therefore, a size L that is too large or too small is not suitable. Through fluid calculation and analysis, it was determined that when L is between 30 and 50 mm, the surface airflow velocity of the bearing outer cover 13 and the motor end cover 14 is between 10 and 15 m / s, which is the optimal airflow velocity. In the structural design, the length of the air guide duct stud 12 is controlled to ensure the L dimension. The L value has been verified in the field and the effect is good.

[0037] Considering that the axial distance between the locking mounting collar 10 and the bearing outer cover 13 and the motor end cover 14 should be as close as possible, the labyrinth ring and bearing end cover of the original bearing assembly were eliminated. However, due to the large amount of coal dust at the motor operating site, which can easily enter the motor and contaminate the motor coils, a curved path dynamic seal structure was added to the mating area between the locking mounting collar 10 and the bearing outer cover 13 (see details). Figure 5 The locking mounting collar 10 is a rotating moving part, and the bearing outer cover 13 is a stationary part. The radial fit clearance between the two is 0.5mm, and the axial fit length is 5mm. The two fit together to form a curved dynamic seal structure to prevent coal dust from entering the motor. The motor protection reaches the IP54 protection level.

[0038] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present utility model and are not intended to limit the present utility model. Any changes or modifications to the above embodiments within the scope of the essential spirit of the present utility model will fall within the scope of the claims of the present utility model.

Claims

1. A cooling device for an electric machine bearing, comprising a rotor and a load end bearing, characterized by: The bearing fan, the ring-shaped air duct and the locking mounting ring are further included. The locking mounting ring is sleeved on the rotor and fixed, the bearing fan is connected with the locking mounting ring and connected on the rotor through the locking mounting ring, and the ring-shaped air duct is installed outside the bearing fan to guide the airflow generated by the bearing fan to the bearing cover of the load end bearing and the motor end cover.

2. The cooling device for a motor bearing according to claim 1, characterized by The locking mounting ring is in a ring shape, an axial slot is formed on the locking mounting ring in the axial direction, a radial slot is formed on the locking mounting ring in the radial direction, the axial slot and the radial slot are staggered with each other, a ring bolt hole is formed on the locking mounting ring in a direction perpendicular to the axial slot, and when the locking mounting ring is sleeved on the rotor, a ring bolt is inserted into the ring bolt hole to change the inner diameter of the locking mounting ring.

3. The cooling device for an electric machine bearing according to claim 2, characterized in that, The radial slot is symmetrical about the axial slot, the width of the radial slot is 3 mm, and the width of the axial slot is 2 mm.

4. The cooling device for a motor bearing according to claim 2, characterized by A bearing fan connecting hole is formed on the end face of the locking mounting ring, and the bearing fan is connected and fixed with the locking mounting ring through a fan fixing bolt.

5. The cooling device for an electric machine bearing according to claim 1 or 4, characterized in that, The bearing fan is an axial flow fan.

6. A cooling device for an electric machine bearing according to claim 5, characterized in that The hub ratio of the axial flow fan is less than 0.5, and the blade length of the axial flow fan is at least 100 mm.

7. A cooling device for an electric machine bearing according to claim 6, characterized in that The axial flow fan is a plastic fan with adjustable blade installation angle.

8. The cooling device for a motor bearing according to claim 1, wherein The axial distance L between the ring-shaped air duct and the motor end cover is adjusted and controlled through the length of the air duct bolt, and the length L is 30-50 mm.

9. The cooling device for a motor bearing according to claim 1, wherein The matching surface of the locking mounting ring towards the motor end cover is provided with a dynamic sealing clamping structure, which forms a curved path dynamic sealing structure with the motor end cover, the radial matching gap between the two is 0.5 mm, and the axial matching length is 5 mm.

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