Cooling system for an axial bearing

Abstract

The invention relates to a cooling system for an axial bearing, comprising: a lubricating fluid storage tank, wherein an axial bearing is arranged centrally inside the lubricating fluid storage tank; ducts arranged inside the lubricating fluid storage tank, said ducts extending axially and parallel to each other, said ducts forming duct modules; a fan fastened to a rotary shaft rigidly connected to said axial bearing, said fan being arranged above the lubricating fluid storage tank; and a protective fan casing surrounding the fan, said protective fan casing comprising openings.

Description

"COOLING SYSTEM FOR THRUST BEARING" TECHNICAL FIELD

[0001] The present invention relates to a cooling system for axial bearings applied in rotating electrical machines used in operating conditions that result in high axial thrust, such as in the case of motors applied to pumps. More specifically, the present invention relates to a modular cooling system, in which the number of ducts (tubes) in the design varies according to the cooling needs of the lubricating fluid in contact with the bearing and of the bearing itself. BACKGROUND OF THE INVENTION

[0002] Rotating electrical machines support relatively high thrust loads. An axial bearing can be provided on the rotating shaft of the rotating electrical machine to reduce friction on the rotating shaft and support axial loads.

[0003] Since such a bearing receives relatively high axial loads, there are friction losses, so the energy lost in friction can be converted into thermal energy, and the thermal energy can act as a heat source that increases the temperature of the bearing.

[0004] Additionally, if the bearing temperature increases, its components may deteriorate and be damaged, reducing the maximum load it can support as well as its lifespan.

[0005] Therefore, lubrication and cooling of the bearing are of utmost importance for it to function correctly and have a long service life.

[0006] Document No. WO2018236154, published on December 27, 2018, on behalf of HYUNDAI ELECTRIC & ENERGY SYSTEMS and entitled: "THURST BEARING COOLING DEVICE" This describes a thrust bearing cooling device that improves its cooling efficiency. The cooling device comprises: a fluid storage tank in which a thrust bearing is installed and a fluid is stored, and whose outer surface is exposed to outside air; and at least one heat exchanger fin disposed in the fluid storage tank.

[0007] Document No. WO2017108562, published on June 29, 2017, on behalf of GE ENERGY POWER CONVERSION TECHNOLOGY and entitled: "SYSTEMS AND METHODS FOR AIR-COOLING MOTOR COMPONENTS" describes a ventilation system that includes a channel formed through a top cover that directs an airflow to cool oil-lubricated bearings applied in rotating electrical machines.

[0008] Document No. US3870907, published on March 11, 1975, in the name of GENERAL ELECTRIC and entitled: "LUBRICANT COOLING APPARATUS FOR A VERTICAL ELECTRIC MOTOR," describes a vertical motor having a thrust bearing immersed in liquid lubricant and provided with a lubricant cooling apparatus comprising a plurality of U-shaped articulated ducts, both legs of which are mounted vertically in the liquid lubricant to provide maximum heat exchange exposure with the lubricant. The legs of each of the U-shaped ducts are radially aligned with the motor drive shaft, and the openings of each of the outermost legs are in communication with the exterior of the motor, while the openings of the innermost legs are in communication with the interior of the motor. Thus, the fan blades associated with the motor rotor are operable to draw air through both of the The U-shaped duct legs extend into the interior of the motor housing, causing air to flow over the heat exchanger fins in the U-shaped ducts to efficiently cool the liquid lubricant and thrust bearing.

[0009] However, a problem with the prior art is that axial bearing cooling systems exhibit relatively low cooling of the lubricating fluid and the bearing in high axial thrust situations.

[0010] Another problem with the state of the art is the fact that cooling systems are not modular. SUMMARY OF THE INVENTION

[0011] One objective of the present invention is to provide a cooling system for thrust bearings that avoids the problems of the prior art.

[0012] This objective is achieved by means of a cooling system for an axial bearing comprising: a lubricant storage tank, in which an axial bearing is disposed in the center of the interior of the lubricant storage tank; ducts disposed within the lubricant storage tank, said ducts extending axially and parallel to each other, said ducts forming duct modules; a fan fixed to a rotating shaft integral with said axial bearing, said fan disposed above the lubricant storage tank; and a fan protection box surrounding the fan, said fan protection box comprising openings.

[0013] Also according to the system of the present invention, the lubricant fluid storage tank It comprises an outer tank surface, cylindrical in shape, facing the external environment; an upper tank surface to seal the upper portion of the lubricating fluid storage tank; and a lower tank surface to seal the lower portion of the lubricating fluid storage tank.

[0014] Furthermore, in the system according to the present invention, in the lower portion of the duct modules, first and second lower sealing elements are arranged between the lower face of the duct modules and the lower tank surface, and in the upper portion of the duct modules, first and second upper sealing elements are arranged between the upper face of the duct modules and the upper tank surface.

[0015] Additionally, the system according to the present invention comprises channels arranged between the duct modules, wherein said channels are fixed inside the surface of a lower tank and extend radially inside the lubricating fluid storage tank; wherein the channels start from a hub of the axial bearing and extend to the region near the surface of the outer tank; and said channels comprising cutouts for fixing them to the inner surface of the lower tank surface.

[0016] According to the system of the present invention, the ducts extend axially from the surface of the lower tank to the surface of the upper tank, through which air circulates.

[0017] Furthermore, the system according to the present invention comprises at least two duct modules, preferably four modules.

[0018] According to the present invention, the ventilation itself can be varied. Machines with lower effort requirements can have smaller fans, while machines with higher requirements can be equipped with larger fans, providing an increase in airflow and heat exchange.

[0019] The modular system also allows for use among the most diverse types of machine constructions, ranging from IC24, IC611, IC511, IC81, up to machines with forced cooling (IC 666, IC516, IC86), with the bearing fan itself being driven by an independent motor driven by an inverter, a system that can operate by varying the rotation according to the demand that the load produces on the bearing and its heating.

[0020] Additionally, in the system according to the present invention, the number of ducts varies according to the cooling needs of the lubricating fluid and the axial bearing.

[0021] Furthermore, in the system according to the present invention, the ducts are arranged away from the axial bearing.

[0022] Furthermore, in the system according to the present invention, the duct modules are fixed, by means of bolted joints, to the surface of the upper tank and to the surface of the lower tank, wherein said bolted joints are radially distributed along the entire perimeter of the duct modules.

[0023] Additionally, the system according to the present invention comprises an air intake region located below the tank.

[0024] The present invention also provides a rotating electrical machine comprising an axial bearing cooling system applied to an upper axial bearing.

[0025] One advantage of the present invention is that it provides an axial bearing cooling system that offers good cooling of the lubricating fluid and the bearing in situations of high axial thrust.

[0026] Another advantage of the present invention is the fact that the cooling system is modular, varying the number of ducts in the system design according to the cooling needs of the lubricating fluid in contact with the bearing and of the bearing itself.

[0027] An additional advantage of the present invention is the fact that the modules and ducts are arranged in such a way as to enhance heat exchange with the internal circulation of oil in the bearing housing between the ducts of the cooling system. The suction and pressure generated in the bearing due to the rotational movement cause the oil to be discharged onto the duct modules of the cooling system; thus, the greater the need to exchange heat from the lubricating fluid with the external environment, the greater the number of modules, and consequently ducts, required. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The objectives and advantages of the present invention will become clearer through the following detailed description of the non-limiting examples and drawings presented at the end of this document:

[0029] Figure 1 is a perspective cross-sectional view of the cooling system for an axial bearing according to a preferred embodiment of the present invention.

[0030] Figure 2 is a perspective cross-sectional view of the axial bearing cooling system, without the fan, according to a preferred embodiment of the present invention.

[0031] Figure 3 is a top cutaway view of the storage tank according to a preferred embodiment of the present invention.

[0032] Figure 4 is a side sectional view of the cooling system for an axial bearing according to a preferred embodiment of the present invention.

[0033] Figure 5 is a side cutaway view of the cooling system for the thrust bearing, without the fan, according to a preferred embodiment of the present invention.

[0034] Figure 5A is an enlarged view of detail A shown in Figure 5 according to a preferred embodiment of the present invention.

[0035] Figure 5B is an enlarged view of detail B shown in Figure 5 according to a preferred embodiment of the present invention.

[0036] Figure 6 is a bottom view of the cooling system for an axial bearing according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0037] Although the present invention may be susceptible to different embodiments, a preferred embodiment is shown in the following detailed discussion, it being understood that the present description should be considered This is an example of the principles of the invention and is not intended to be limited to what has been illustrated and described herein.

[0038] Figures 1 and 2 illustrate a preferred embodiment of the cooling system for the axial bearing 10 according to the present invention.

[0039] According to Figures 1 and 2, the cooling system comprises a lubricant storage tank 20, ducts 30 and a fan 40.

[0040] According to Figures 1 and 2, the axial bearing 10 is located in the center of the interior of the lubricating fluid storage tank 20, such that said axial bearing 10 is in direct contact with the fluid in the storage tank 20. Said axial bearing 10 is coupled to a rotating shaft 50 of the rotating electric machine, said rotating shaft 50 being arranged so as to pass through the center of the storage tank 20.Furthermore, the lubricating fluid storage tank 20 comprises an outer tank surface 21, of cylindrical shape, facing the external environment; an upper tank surface 22 for sealing the upper portion of the fluid storage tank 20, wherein said upper tank surface 22 is formed by a first upper tank surface member 22c and a second upper tank surface member 22d; and a lower tank surface 23 for sealing the lower portion of the fluid storage tank 20.

[0041] According to Figures 1 and 2, the cooling system comprises ducts 30 arranged within the lubricating fluid storage tank 20, said ducts 30 extending axially and parallel to each other. forming duct modules 31. Additionally, the ducts 30 are arranged away from the axial bearing 10 and do not come into contact with it.

[0042] According to Figure 3, which shows the internal portion of the lubricating fluid storage tank 20, the cooling system comprises at least two duct modules 31, said modules 31 being separated by channels 32, such that the channels 32 are arranged between the duct modules 31. In the embodiment presented, four modules 31 are identified forming the cooling system. Furthermore, the channels 32 are fixed inside the lower tank surface 23 and extend radially inside the lubricating fluid storage tank 20. According to Figures 2 and 3, the channels 32 start from the hub 11 of the axial bearing 10 and extend to the region near the outer tank surface 21. Additionally, channels 32 have cutouts 321 that serve to fix them to the inner surface of the lower tank surface 23.

[0043] According to Figures 2 and 3, the ducts 30 extend axially from the surface of the lower tank 23 to the surface of the upper tank 22.

[0044] According to Figures 1 and 4, the fan 40 is positioned above the lubricating fluid storage tank 20 and is fixed to the rotating shaft 50 of the rotating electric machine. Thus, the fan 40 is rotated by the rotational movement of the shaft 50, generating an airflow that passes through the interior of the ducts 30. External air is drawn in by the fan 40 and admitted into the cooling system through an air intake region 65 located below the tank 20. The air then passes through the... The ducts 30 exchange heat with the lubricating fluid located inside the tank 20 and around the ducts 30. This heat exchange mechanism results in a reduction in the temperature of the lubricating fluid, and a consequent increase in the temperature of the air admitted inside the ducts 30. The reduction in the temperature of the lubricating fluid is necessary because it is responsible both for lubricating the axial bearing 10 and for reducing its operating temperature; that is, the lubricating fluid assists in removing heat from said axial bearing 10. The ventilation circuit of the upper bearing is completed by the exit of heated air from inside the ducts 30 through openings 70 arranged along the entire lateral surface of the fan protection box 80, said fan protection box 80 surrounding the upper surface and the lateral surface of the fan 40.These openings 70 are arranged along the entire length of the protective box 80, and are preferably combined with the use of screens or grids, which guarantee the degree of protection required for the equipment, that is, they prevent foreign elements from entering the interior of the machine.

[0045] Additionally, the rotational movement of shaft 50 generates a pumping phenomenon of the oil present in the storage tank 20, due to the particular geometry of the axial bearing 10 which is partially submerged, so that the oil flow generated in the cooling system circulates around the ducts 30 and has as its suction point the end of the channels 32. This oil flow assists in the heat exchange necessary for the correct functioning of the bearing 10 subjected to axial loads.

[0046] According to the present invention, the number of ducts 30 present in the duct modules 31 of the cooling system varies in the design according to the cooling needs of the lubricating fluid and the axial bearing 10. Thus, in applications where a higher machine torque is required, it is possible to design a cooling system with a greater number of ducts 30 to improve the cooling provided. In addition, the sizing of the fan 40 can be varied in order to optimize the airflow and heat exchange.

[0047] Modular construction presents the challenge of maintaining the structure's watertightness, since the operation of rotating electrical machines invariably involves vibration scenarios. According to Figures 5, 5A and 5B, the watertightness of the lower portion of the cooling system is achieved through the use of lower sealing elements in the lower portion of the duct modules 31, such as rubber rings, arranged between the lower face of the duct modules 31a, 31b and the upper face of the lower tank surface 23a, 23b.More specifically, the first lower sealing elements 60 and the second lower sealing elements 61 are arranged between the lower face of the duct modules 31a, 31b, respectively, and the upper face of the lower tank surface 23a, 23b, respectively, in such a way that the first lower sealing elements 60 are arranged closer to the rotating shaft 50 than the second lower sealing elements 61. Thus, the compression guaranteed on the surfaces of the elements offers the guarantee of tightness of the modular cooling system.

[0048] On the other hand, the tightness of the upper portion of the cooling system is ensured in a manner analogous to that of the lower portion, that is, by the combined use of at least two sealing elements mounted against the surfaces of the duct modules 31 and the upper tank surface 22. Thus, upper sealing elements are used in the upper portion of the duct modules 31, namely, first upper sealing elements 60b and second upper sealing elements 61b. The first upper sealing elements 60b are arranged between the upper face of the duct modules 31c and the upper face of the first member of the upper tank surface 22c, and the lower surface of an upper frame of the duct modules 31d. In addition to the first upper sealing elements 60b, spacers 62 are used, positioned adjacent to the first upper sealing elements 60b.The second upper sealing elements 61b are arranged between the members that form the upper tank surface 22, that is, between the lower face of a first member of the upper tank surface 22c, and the upper face of a second member of the upper tank surface 22d. The first upper sealing elements 60b are arranged closer to the rotating axis 50 than the second upper sealing elements 61b.

[0049] Thus, a set of sealing elements, consisting of first 60 and second 61 lower sealing elements, is used per duct module 31 in the lower portion, and an analogous set, consisting of first 60b and second 61b upper sealing elements, is used per duct module 31 in the upper portion.

[0050] The use of independent sealing elements per duct module 31 allows for the independent maintenance of each duct module 31, should replacement of said sealing elements become necessary. This feature also allows the sealing elements to have smaller dimensions, making their positioning easier during assembly in the cooling system modules.

[0051] In addition to the sealing element system, as shown in Figures 2 and 6, the duct module 31 is pressed against the tank 20 by means of bolted joints 100 radially distributed along the entire perimeter of the duct modules 31. Thus, the duct modules 31 are fixed, by means of the bolted joints 100, to the surface of the upper tank 22 and to the surface of the lower tank 23.

[0052] Furthermore, the cooling system according to the present invention is applied to an upper axial bearing of rotating electrical machines.

[0053] In addition to the implementation presented above, the same inventive concept could be applied to other alternatives or possibilities for using the invention.

[0054] Although the present invention has been described in relation to certain preferred embodiments, it should be understood that the invention is not intended to be limited to those particular embodiments. Rather, it is intended to encompass all possible alternatives, modifications and equivalences within the spirit and scope of the invention, as defined by the appended claims.

Claims

CLAIMS 1. A cooling system for a thrust bearing (10), comprising: a lubricating fluid storage tank (20), wherein a thrust bearing (10) is arranged in the center of the interior of the lubricating fluid storage tank (20); ducts (30) arranged within the lubricating fluid storage tank (20), said ducts (30) extending axially and parallel to each other, said ducts (30) forming duct modules (31); a fan (40) fixed to a rotary shaft (50) integral with said thrust bearing (10), said fan (40) arranged above the lubricating fluid storage tank (20); and a fan protective housing (80) surrounding the fan (40), said fan protective housing (80) comprising openings (70).

2. Cooling system, according to claim 1, characterized by the fact that the lubricating fluid storage tank (20) comprises an outer tank surface (21), of cylindrical shape, facing the external environment; an upper tank surface (22) for sealing the upper portion of the lubricating fluid storage tank (20); and a lower tank surface (23) for sealing the lower portion of the lubricating fluid storage tank (20).

3. Cooling system, according to claim 1, characterized by the fact that in the lower portion of the duct modules (31), first and second lower sealing elements (60, 61) are arranged between the lower face of the duct modules (31a, 31b) and the lower tank surface (23), and in the upper portion of the duct modules (31) first and second upper sealing elements (60b, 61b) are arranged between the upper face of the duct modules (31c) and the upper tank surface (22).

4. Cooling system according to claim 1, characterized in that it additionally comprises channels (32) arranged between the duct modules (31), wherein said channels (32) are fixed inside the surface of a lower tank (23) and extend radially inside the lubricating fluid storage tank (20); wherein the channels (32) start from a hub (11) of the thrust bearing (10) and extend to the region close to the surface of the outer tank (21); and said channels (32) comprising cutouts (321) for fixing them to the inner surface of the surface of the lower tank (23).

5. Cooling system, according to claim 1, characterized by the fact that the ducts (30) extend axially from the lower tank surface (22) to the upper tank surface (23), through which air circulates.

6. Cooling system according to claim 1, characterized in that it comprises at least two duct modules (31), preferably four modules.

7. Cooling system according to claim 1, characterized in that the ducts (30) are arranged away from the axial bearing (10).

8. Cooling system, according to claim 1, characterized by the fact that the duct modules (31) are fixed, by means of bolted joints (100), to the upper tank surface (22) and to the lower tank surface (23), in which said bolted joints (100) are radially distributed along the entire perimeter length of the duct modules (31).

9. Cooling system, according to claim 1, characterized by the fact that it comprises an air intake region (65) located below the tank (20).

10. Rotating electrical machine comprising a cooling system as defined in any one of claims 1 to 9, characterized in that said cooling system is applied to an upper axial bearing.

Images