A bushing bearing cooling system

Abstract

The application relates to the technical field of oil circuit lubrication and cooling of water turbine bearings, and discloses a shaft collar type bearing cooling system, which comprises a bearing bush, the bearing bush is sleeved on a shaft collar, the shaft collar is immersed in an oil pool, a plurality of cold oil circulation oil circuits and hot oil circulation oil circuits are arranged on the bearing bush, and the hot oil circulation oil circuits are connected with coolers, characterized in that: an oil nozzle is arranged at the bottom of the shaft collar, the oil nozzle is communicated with the hot oil circulation oil circuits, the oil nozzle pumps cold oil into the hot oil circulation oil circuits, the hot oil circulation oil circuits pass hot oil into the coolers, the hot oil is cooled and then passed into the cold oil circulation oil circuits, and the cold oil circulation oil circuits are communicated with the oil nozzle; the working temperature of the bearing is controlled to be below 60 DEG C; the hot oil circulation and exchange efficiency are high; the service life of the bearing is prolonged; and the bearing can be prevented from burning the bush and even from emergency shutdown.

Description

Technical Field

[0001] This invention relates to the field of oil circuit lubrication and cooling technology for turbine bearings, specifically to a shaft-type bearing cooling system. Background Technology

[0002] A shaft-type bearing is a radial self-lubricating sliding bearing, mainly including two structures: cylindrical self-lubricating bearing and segmented self-lubricating bearing. Its main function is to bear the radial unbalanced force generated by the unit during high-speed rotation, reduce the radial runout of the unit, and ensure that the unit can operate stably for a long time.

[0003] The operating speed of the shaft-type bearing is relatively high, usually between 300 r / min and 750 r / min. Due to the unbalanced load of the rotating part of the unit, the shaft and the bearing shell will come into frictional contact during operation, and a large amount of heat will be generated on the surface of the bearing shell. If this heat is not carried away by the cooling system in time, it will cause the oil temperature in the lubrication system to rise rapidly. When it exceeds the allowable temperature rise of the bearing, it will cause the bearing to burn out or even cause a safety accident such as emergency shutdown.

[0004] Chinese patent document CN207513733U discloses a cooling device for a mixed-flow turbine water guide bearing, including an oil circulation cooling system and an oil spray pipe connected to the cooling system. The oil circulation cooling system is an external heat exchanger that extracts hot oil from the water guide oil tank to cool it down, and then sprays it into the water guide oil tank through the oil spray pipe to cool the bearing bush, thereby reducing the temperature of the water guide bearing. The water guide oil tank is equipped with a baffle to separate the cold oil and the hot oil.

[0005] The existing technology has the following shortcomings: low bearing cooling efficiency, inability to effectively control the bearing operating temperature, resulting in excessively high operating temperature, which can easily lead to bearing burnout or even emergency shutdown safety accidents. Summary of the Invention

[0006] The purpose of this invention is to provide a shaft-type bearing cooling system to solve the problem of bearing burnout or even emergency shutdown caused by excessively high bearing operating temperature.

[0007] To achieve the above objectives, the present invention provides a shaft collar type bearing cooling system, including a bearing bush, the bearing bush being sleeved on a shaft collar, the shaft collar being immersed in an oil bath, and the bearing bush being provided with multiple cold oil circulation channels and hot oil circulation channels, the hot oil circulation channels being connected to a cooler. The system is characterized in that: an oil nozzle is provided at the bottom of the shaft collar, the oil nozzle being connected to the hot oil circulation channels, the oil nozzle pumping cold oil into the hot oil circulation channels, the hot oil circulation channels passing hot oil into the cooler, cooling it, and then passing it into the cold oil circulation channels, the cold oil circulation channels being connected to the oil nozzle.

[0008] To facilitate oil pumping, the cooler is located outside the oil sump, and the oil nozzle is located inside the oil sump.

[0009] To increase the pressure difference between the lubricating oil inside and outside the oil sump, the range of the oil nozzle is 0.05m to 0.12m.

[0010] Furthermore, the radial angle between the oil nozzle and the shaft is 0-90°.

[0011] To improve cooling efficiency, an oil separator is provided at the bottom of the bearing bush, which separates the bottom oil passage of the cold oil circulation circuit from the bottom oil passage of the hot oil circulation circuit.

[0012] Furthermore, the oil separator is annular and has multiple cold oil holes and hot oil holes. The cold oil circulation path and the hot oil circulation path are respectively connected to the cold oil holes and the hot oil holes. The hot oil hole is connected to one end of the oil nozzle, and the cold oil hole is connected to the other end of the oil nozzle. The flow paths of cold and hot oil are independent and flow smoothly, restricting hot oil from entering the inner side of the oil tank.

[0013] In order to quickly guide hot oil to flow to the cooler along the hot oil circulation circuit, the hot oil circulation circuit includes oil passages along the axial and radial directions of the bearing base. The radial oil passage is connected to the cooler through a pipeline. The top of the axial oil passage is provided with a screw plug to block the axial oil passage and prevent oil leakage from above.

[0014] Furthermore, the inlet of the cold oil circulation circuit is lower than the highest oil level in the oil sump.

[0015] The beneficial effects of this invention are: improving the pumping capacity of the bearing oil circuit lubrication and cooling system, effectively controlling the bearing's operating temperature, extending the bearing's service life; increasing the pressure difference between the inner and outer sides of the oil sump by adding oil nozzles, ensuring stable, smooth, and rapid heat exchange; considering that all the heat of the lubricating oil in the bearing oil sump comes from the mechanical friction between the bearing collar and the bearing bush, and that the rotational speed of the bearing collar agitating the lubricating oil is constant, according to the principle of energy conservation: Given the rotational speed ω, the inner diameter of the shaft collar D, and the gravitational acceleration g, to increase the oil level in the oil circuit, the length S of the radial oil nozzle of the shaft collar needs to be increased. The greater the oil level, the greater the pressure difference, the better the oil pumping effect, and the higher the efficiency of hot oil circulation and exchange. This effectively avoids the problem of bearing burnout or even emergency shutdown caused by excessively high bearing operating temperature. Compared with the prior art that only uses partitions for separation, the cold and hot oil circulation circuits of the shaft collar in this invention are completely independent and do not interfere with each other. This restricts hot oil from entering the inner side of the oil sump, ensures a smooth hot oil circulation path, stabilizes the heat exchange with the cooler, and fully cools the hot oil on the outside of the oil sump. The cold oil fully absorbs the heat generated by the bearing bush and the shaft collar, ensuring that the oil temperature in the bearing area is below the standard value of 60°C. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of Embodiment 1; Figure 2 for Figure 1 A partial structural diagram; Figure 3 for Figure 1 A schematic diagram of the structure of a neural network; Figure 4 Here is a schematic diagram of the oil separator: Figure 5 This is a cloud map showing the static pressure distribution of the lubricating oil.

[0017] Reference numerals in the attached diagram: 1. Spindle; 2. Shaft collar; 3. Bearing shell; 4. Cooler; 5. Oil sump; 6. Cold oil circulation circuit; 7. Hot oil circulation circuit; 8. Oil nozzle; 9. Oil separator; 901. Cold oil hole; 902. Hot oil hole; 10. Plug. Detailed Implementation

[0018] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. However, the present invention is not limited to these embodiments. Any improvements made to the present invention without departing from the principle of the present invention also fall within the protection scope of the claims of the present invention. Example 1

[0019] like Figure 1-4 As shown, a shaft-type bearing cooling system includes a shaft collar 2, a bearing shell 3, and a cooler 4. The shaft collar 2 is located on a main shaft 1 and rotates with the main shaft 1. The bearing shell 3 is sleeved on the shaft collar 2. The shaft collar 2 is immersed in an oil bath 5. Multiple independent cold oil circulation passages 6 and hot oil circulation passages 7 are spaced apart along the axial direction of the bearing shell 3. The hot oil circulation passages 7 are connected to the cooler 4. The cooler 4 is located on a platform outside the oil bath 5. An oil nozzle 8 is provided at the bottom of the shaft collar 2, located inside the oil bath 5. The oil nozzle 8 is connected to the hot oil circulation passage 7, and pumps cold oil into the cooling system. In the hot oil circulation circuit 7, hot oil is passed into the cooler 4 for cooling and then discharged into the oil sump 5. The oil sump 5 is connected to the oil inlet at the top of the cold oil circulation circuit 6. The oil outlet of the cold oil circulation circuit 6 is located inside the oil sump 5. Cold oil enters the grease nipple 8 through the inside of the oil sump 5 to achieve the circulation and cooling of the lubricating oil. The oil inlet of the cold oil circulation circuit 6 is lower than the highest oil level of the oil sump 5. During the rotation of the bearing 3, the lubricating oil inside the oil sump 5 is forced into the grease nipple 8 and pumped into the outside of the oil sump 5 after absorbing heat through the hot oil circulation circuit 7, thereby achieving heat exchange with the bearing ring 2 and the bearing 3.

[0020] The bearing bush 3 is provided with an oil separator plate 9 at its bottom. The oil separator plate 9 separates the bottom oil passages of the cold oil circulation passage 6 and the hot oil circulation passage 7, preventing them from being directly connected. The oil separator plate 9 is annular and has 6 cold oil holes 901 and 6 hot oil holes 902. The cold oil circulation passage 6 and the hot oil circulation passage 7 are respectively connected to the cold oil holes 901 and the hot oil holes 902. The hot oil hole 902 is connected to one end of the oil nozzle 8, and the cold oil hole 901 is connected to the other end of the oil nozzle 8.

[0021] The hot oil circulation circuit 7 includes oil circuits along the axial and radial directions of the bearing base. The radial oil circuit is connected to the cooler 4 through a pipeline. The top of the axial oil circuit is provided with a screw plug 10 to block and prevent oil leakage from above.

[0022] The mass of the lubricating oil in the grease nipple 8 is m, the centrifugal force it experiences is F, the work done by the lubricating oil entering the grease nipple 8 under the centrifugal force is Wc, the kinetic energy of the lubricating oil increased in the grease nipple 8 is ΔEk, and theoretically, the oil level height can be increased by Δh by increasing the grease nipple 8. Because when the bearing is working, the shaft collar 2 of the main shaft 1 bears a certain amount of radial unbalanced force, which causes the bearing shell 3 to contact and rub against the shaft collar 2, generating heat.

[0023] Considering that all the heat of the lubricating oil in the oil tank 5 comes from the mechanical friction between the bearing ring 2 and the bearing bush 3, and the rotational speed of the bearing ring 2 in stirring the lubricating oil is constant, according to the principle of energy conservation: Wc=F·Scosθ F=mω 2 r=mω 2 ×(0.5D) According to the above formula, for a shaft-type bearing with fixed operating parameters, such as operating speed ω, shaft inner diameter D, and gravitational acceleration g, if the oil level in its oil circuit is to be increased, the length S of the oil nozzle 8 in the radial direction of the shaft 2 needs to be increased.

[0024] The main parameters of the shaft-type bearing are: rotational speed of 300 r / min, height H of the bearing bush 3 of 0.3 m, inner diameter D of the shaft collar 2 of 0.6 m, length S of the grease fitting 8 of 0.1 m (including the oil hole), radial angle between the grease fitting 8 and the shaft collar 2 of 45°, gravitational acceleration of 9.81 m / s², and reference pressure of 1.01 × 10⁻⁶ m / s². 5Pa. Using the above formula, the theoretical net increase in oil level Δh is calculated to be 2.134m. Considering local and friction losses in the oil circuit, the increase in oil level is 1.28m. This value is much greater than the height H = 0.3m of the bearing 3, ensuring smooth and continuous heat exchange between hot and cold oils through the oil circuit. Furthermore, a CFD numerical calculation method was used for comparison, yielding the hydrostatic pressure distribution cloud map of the lubricating oil in the hot oil circulation circuit 7, as shown below. Figure 5 As shown in the diagram, the location of the maximum oil pressure in the oil pipe is at the inlet of the nozzle, with a maximum value of 1.33 × 10⁻⁶. 5 The oil pressure at the oil pipe outlet is approximately 1.22 × 10 Pa. 5 All pressures are greater than the reference pressure, and the net pressure difference between the inlet and outlet of the oil pipe is 0.11 × 10⁻⁶ Pa. 5 Pa, the equivalent oil level height difference is 1.1m, which is greater than the height of bearing shell 3 by 0.3m, indicating that the lubricating oil in the oil pipe flows smoothly. The selected bearing operating speed is 300r / min, which is the minimum value within the operating speed range of this type of bearing, and the other parameters are taken as reasonable average levels.

Claims

1. A shaft collar type bearing cooling system, comprising a bearing shell (3), the bearing shell (3) being sleeved on a shaft collar (2), the shaft collar (2) being immersed in an oil bath (5), the bearing shell (3) being provided with multiple cold oil circulation passages (6) and hot oil circulation passages (7), the hot oil circulation passages (7) being connected to a cooler (4), characterized in that: The bottom of the bearing (2) is provided with an oil nozzle (8), which is located inside the oil sump (5). The oil nozzle (8) is connected to the hot oil circulation circuit (7), and pumps cold oil into the hot oil circulation circuit (7). The hot oil circulation circuit (7) then passes the hot oil into the cooler (4), and after cooling, it passes into the cold oil circulation circuit (6). The cold oil circulation circuit (6) is connected to the oil nozzle (8). The bottom of the bearing bush (3) is provided with an oil separator (9), which separates the cold oil circulation circuit (6) from the oil separator. The bottom oil passage of the hot oil circulation oil passage (7) is spaced apart; the oil separator (9) is annular, and the oil separator (9) is provided with multiple cold oil holes (901) and hot oil holes (902). The cold oil circulation oil passage (6) and the hot oil circulation oil passage (7) are respectively connected to the cold oil holes (901) and the hot oil holes (902). The hot oil hole (902) is connected to one end of the oil nozzle (8), and the cold oil hole (901) is connected to the other end of the oil nozzle (8). By adding the oil nozzle (8), the pressure difference of the lubricating oil inside and outside the oil pool (5) is increased.

2. The shaft-mounted bearing cooling system according to claim 1, characterized in that: The cooler (4) is located outside the oil tank (5).

3. The shaft-mounted bearing cooling system according to claim 1 or 2, characterized in that: The range of the nozzle (8) is 0.05m to 0.12m.

4. The shaft-mounted bearing cooling system according to claim 1 or 2, characterized in that: The radial angle between the oil nozzle (8) and the shaft collar (2) is 0-90°.

5. The shaft-mounted bearing cooling system according to claim 3, characterized in that: The radial angle between the oil nozzle (8) and the shaft collar (2) is 0-90°.

6. The shaft-mounted bearing cooling system according to claim 5, characterized in that: The hot oil circulation circuit (7) includes oil circuits along the axial and radial directions of the bearing (3) base. The radial oil circuit is connected to the cooler (4) through a pipeline, and the top of the axial oil circuit is provided with a screw plug (10).

7. The shaft-mounted bearing cooling system according to claim 6, characterized in that: The oil inlet of the cold oil circulation circuit (6) is lower than the highest oil level of the oil tank (5).

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