Oil-cooled motor with stator capable of being cooled in multiple directions

Abstract

The invention discloses an oil-cooled motor with a multidirectional stator cooling function, and belongs to the technical field of oil-cooled motor structures, the motor comprises a motor assembly and an oil sleeve assembly, a stator iron core with a winding, a rotor assembly, a whole machine oil inlet hole and a whole machine oil outlet hole are arranged in a casing of the motor assembly; the oil sleeve assembly is composed of two oil sleeves and installed at the two ends of the stator iron core, an S-shaped oil way space is formed through oil way ribs distributed in a staggered mode, and multi-direction cooling of the outer surface and the end face of the stator iron core is achieved through the combination of radial oil holes and axial oil holes, and in the rotor assembly, a rotating shaft oil way and inclined multi-angle pressing plate oil holes of a rotor pressing plate act synergistically. According to the invention, the split type oil sleeve is designed to replace a traditional punching sheet oil duct, the process is simplified, the cost is reduced, the heat dissipation efficiency is improved by more than 30%, the problems of non-uniform cooling and local high temperature are solved, the service life of the stator is prolonged, and the service life of the stator is prolonged. And the power density and the long-term reliability of the motor are obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil-cooled motor structures, and more particularly to an oil-cooled motor with a multi-directional stator cooling system. Background Art

[0002] In the field of oil-cooled motors, the cooling efficiency of the stator core and windings directly affects the power density and operational reliability of the motor. In existing technologies, the main solutions for stator cooling include the following:

[0003] (1) Stator core outer diameter expansion scheme: By increasing the outer diameter of the stator core, different shapes of stamping sheets are stacked to form internal oil channels to enhance core cooling. However, this scheme has significant drawbacks: the increase in the stator outer diameter leads to deterioration of electromagnetic performance, affecting motor efficiency; multiple stamping dies need to be designed, the stacking process is complex, and the manufacturing cost is high.

[0004] (2) Centripetal winding end cooling solution: Centripetal oil holes are formed by stacking stamping sheets to cool the stator winding ends. However, this solution has the following problems: it requires the coordination of stamping sheets of multiple specifications, which makes oil hole processing difficult and leads to low production efficiency; the oil holes are unevenly distributed, resulting in significant differences in the cooling effect of the ends and easily forming local high-temperature areas; the oil ring or oil pipe can only cover the outer surface of the end and cannot effectively cool the axial middle position of the end. Especially when there are many layers of flat wire, the temperature rise problem in the middle area is prominent.

[0005] (3) Rotor oil-spinning cooling solution: This solution utilizes the centrifugal force of the rotor to spin the cooling oil toward the inner surface of the stator winding ends. However, the fixed angle of the oil-spinning holes in traditional designs only covers a local area of the end, limiting the cooling area and preventing uniform coverage of the entire inner surface. This results in cooling blind spots and the risk of localized high temperatures.

[0006] In addition, the existing technology also has the following systemic deficiencies: the cooling paths of the stator core and the winding ends are separated, making it difficult to achieve coordinated heat dissipation; the oil circuit design relies on a complex punching structure, with poor process flexibility and scalability; the temperature rise problem caused by local uneven cooling limits the long-term reliability of the motor under high power density conditions. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention provides an oil-cooled motor with multi-directional stator cooling. This oil-cooled motor with multi-directional stator cooling solves the pain points of traditional oil-cooled motors such as uneven cooling, complex process, and local overheating through an innovative multi-directional oil circuit design, a split component structure, and a rotor-stator collaborative cooling mechanism.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] An oil-cooled motor with multi-directional stator cooling, comprising:

[0010] The motor assembly includes a housing, a stator core with windings, and a rotor assembly installed in the housing. The housing is provided with an oil inlet for the entire machine, an oil outlet for the entire machine, and an oil outlet for the stator core area.

[0011] An oil sleeve assembly includes two oil sleeves, both of which are located in the casing and are respectively installed at the two ends of the stator core with windings. The stator core with windings, the casing and the space between the two oil sleeves form an oil path space. The oil inlet hole of the whole machine and the oil outlet hole of the stator core area are connected to the oil path space. The oil outlet hole of the stator core area is connected to the oil outlet hole of the whole machine. A plurality of oil channel ribs are provided on opposite sides of the two oil sleeves. The plurality of oil channel ribs are staggered and distributed to form an "S"-shaped oil path in the oil path space. Both oil sleeves are provided with a plurality of radial oil holes and a plurality of axial oil holes that are connected to the oil path space. The radial oil holes face the outer surface of the end of the stator core with windings, and the axial oil holes face the end surface of the end of the stator core with windings.

[0012] Furthermore, the rotor assembly includes a rotating shaft, a rotor pressure plate, a rotor core segment and a plurality of magnets. The rotor core segment is provided with a plurality of magnet slots, the magnets are installed on the magnet slots, the rotor core segment is installed on the rotating shaft, and the rotor pressure plate is respectively located at both ends of the rotor core segment. A rotating shaft oil circuit is provided in the rotating shaft, and a plurality of pressure plate oil channels and a plurality of pressure plate oil holes are provided on the rotor pressure plate. The rotating shaft oil circuit, the pressure plate oil channel, the magnet slots and the pressure plate oil holes are connected in sequence, and the pressure plate oil holes face the inner surface of the end of the stator core with windings.

[0013] Furthermore, the pressure plate oil holes are arranged obliquely on the rotor pressure plate, and the inclination angles of several pressure plate oil holes are different and all face the end of the stator core with winding.

[0014] Furthermore, the oil sleeve is provided with a diverter loop and several axial flow channels connected to the diverter loop, an oil inlet for communication is provided between the diverter loop and the oil passage space, and the several axial flow channels are respectively connected to several radial oil holes and several axial oil holes.

[0015] Furthermore, a plurality of radial oil holes are distributed in a ring shape on the oil sleeve to form a plurality of groups, and each group includes a plurality of radial oil holes arranged at an axial distance.

[0016] Furthermore, the end of the oil sleeve is provided with a plurality of protruding rods distributed in a ring shape, and the plurality of axial oil holes are respectively located on the plurality of protruding rods and face the end surface of the end of the stator core with winding.

[0017] Furthermore, the stator core with windings includes a non-parallel end, a stator core and a parallel end, the two oil jackets include a non-parallel end oil jacket and a parallel end oil jacket assembly, the non-parallel end oil jacket is installed at the non-parallel end, the parallel end oil jacket assembly includes a parallel end oil jacket and an oil ring, and the parallel end oil jacket and oil ring are both installed at the parallel end.

[0018] Furthermore, an oil sleeve stop is provided in the casing at the non-parallel end side, and the oil sleeve at the non-parallel end is positioned and installed through the oil sleeve stop.

[0019] Furthermore, an oil sleeve mounting step surface is provided in the casing at the parallel head end side, and a first mounting platform and a second mounting platform are provided on the parallel head end oil sleeve and the oil ring respectively. The first mounting platform of the parallel head end oil sleeve is positioned and installed with the oil sleeve mounting step surface, and the first mounting platform of the parallel head end oil sleeve and the second mounting platform of the oil ring are installed and connected to each other.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. Multi-directional collaborative cooling, comprehensive coverage of heat sources: The stator core is cooled through an "S"-shaped oil circuit, and radial and axial oil holes are used to cool the outer surfaces and end faces of both ends; the multi-angle oil holes of the rotor pressure plate cover the inner surface of the stator end, forming a three-dimensional cooling network of "outer-inner-axial end face", which completely eliminates local high temperatures.

[0022] 2. Structural simplification and process optimization: The oil sleeve assembly replaces the traditional punching die oil channel, reducing manufacturing complexity and cost; the split oil sleeve and oil ring design takes into account both installation convenience and cooling performance, improving assembly efficiency.

[0023] 3. Efficient heat dissipation and improved reliability: The oil circuit space and shunt loop design increase the heat exchange area, improving heat dissipation efficiency by more than 30%; the rotor magnets and stator windings are cooled synchronously, extending the motor life and adapting to high power density conditions.

[0024] 4. Flexible adaptability and scalability: The oil sleeve and oil ring can be customized according to different motor sizes, with strong compatibility; the oil outlet can be equipped with a nozzle to further enhance the cooling effect and meet diverse application needs.

[0025] The present invention solves the pain points of traditional oil-cooled motors such as uneven cooling, complex processes, and local overheating through an innovative multi-directional oil circuit design, split component structure, and rotor-stator collaborative cooling mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0027] Figure 1 The internal schematic diagram of an oil-cooled motor with multi-directional stator cooling;

[0028] Figure 2 This is a schematic diagram of two oil jackets installed on a stator core with windings;

[0029] Figure 3 This is a structural diagram of the non-parallel end oil jacket;

[0030] Figure 4 This is a structural diagram of the parallel end oil jacket;

[0031] Figure 5 It is the structural diagram of the oil ring;

[0032] Figure 6 is a schematic structural diagram of the rotor assembly;

[0033] Figure 7 Schematic diagram of the structure of the rotor pressure plate.

[0034] The following are marked in the figure: 1. Front cover; 2. Casing; 201. Oil inlet of the whole machine; 202. Oil outlet of the stator core area; 203. Oil outlet of the whole machine; 204. Oil jacket stop; 205. Oil jacket mounting step; 3. Oil jacket at the non-parallel end; 4. Stator core with winding; 401. Non-parallel end; 402. Stator core; 403. Parallel end; 5. Oil jacket at the parallel end; 6. Oil ring; 7. Rear cover; 8. Bearing; 9. Rotor Shaft; 901, rotating shaft oil circuit; 10, rotor core segment; 1001, magnetic steel slot; 11, rotor pressure plate; 1101, pressure plate oil hole; 1102, pressure plate oil channel; 12, magnetic steel; 13, radial oil hole; 14, axial oil hole; 15, axial flow channel; 16, radial flow channel; 17, oil channel rib; 18, diverter loop; 19, oil inlet; 20, oil circuit space; 21, first mounting platform; 22, second mounting platform; DETAILED DESCRIPTION

[0035] In the description of the present invention, it should be noted that, for directional words, such as the terms "center", "horizontal (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like, indicating directions and positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific scope of protection of the present invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Therefore, the terms "first" and "second" may explicitly or implicitly refer to one or more of these features. Throughout the description of the present invention, "several" and "a number" mean two or more, unless otherwise specifically defined.

[0037] An oil-cooled motor with multi-directional stator cooling, such as Figure 1-3 Shown, including:

[0038] The motor assembly includes a housing 2, a stator core 4 with windings installed in the housing 2, and a rotor assembly. The housing 2 is provided with an oil inlet 201 for the whole machine, an oil outlet 203 for the whole machine, and an oil outlet 202 for the stator core area.

[0039] The housing 2 is provided with a front cover 1 and a rear cover 7 at both ends, and a bearing 8 is provided between the rotating shaft 9 and the front cover 1 and the rear cover 7;

[0040] The oil sleeve assembly includes two oil sleeves, both of which are located in the casing 2 and are respectively installed at the two ends of the stator core 4 with windings. The stator core 4 with windings, the casing 2 and the space between the two oil sleeves form an oil path space 20. The oil inlet hole 201 of the whole machine and the oil outlet hole 202 of the stator core area are connected to the oil path space 20. The oil outlet hole 202 of the stator core area is connected to the oil outlet hole 203 of the whole machine. A plurality of oil channel ribs 17 are provided on opposite sides of the two oil sleeves. The plurality of oil channel ribs 17 are staggered and distributed with each other so that the oil path space 20 forms an "S"-shaped oil path. Both oil sleeves are provided with a plurality of radial oil holes 13 and a plurality of axial oil holes 14 that are connected to the oil path space 20. The radial oil holes 13 face the outer surface of the end of the stator core 4 with windings, and the axial oil holes 14 face the end surface of the end of the stator core 4 with windings.

[0041] Specifically, staggered oil channel ribs 17 are provided on opposite sides of the two oil jackets to form an "S"-shaped oil path. After the cooling oil enters the oil path space 20 from the oil inlet hole 201 of the whole machine, it flows along the "S"-shaped path, prolonging the residence time of the oil on the surface of the stator core and increasing the contact area with the stator core, thereby significantly improving the heat exchange efficiency and avoiding oil short-circuiting. At the same time, the radial oil holes 13 and the axial oil holes 14 are respectively oriented to the side and end faces of the stator core. The radial and axial oil holes work together to cover the outer surface and end of the stator core. The cooling uniformity is better than that of the traditional single-path design, and multi-directional jet cooling is achieved. In addition, the use of the oil jacket assembly does not require dependence on the stator punching mold, which simplifies the manufacturing process and reduces production costs.

[0042] Preferably, Figure 1 and Figure 6As shown, the rotor assembly includes a rotating shaft 9, a rotor pressure plate 11, a rotor core segment 10 and a plurality of magnetic steels 12. The rotor core segment 10 is provided with a plurality of magnetic steel slots 1001, and the magnetic steels 12 are installed on the magnetic steel slots 1001. The rotor core segment 10 is installed on the rotating shaft 9, and the rotor pressure plates 11 are respectively located at both ends of the rotor core segment 10. A rotating shaft oil passage 901 is provided in the rotating shaft 9, and a plurality of pressure plate oil passages 1102 and a plurality of pressure plate oil holes 1101 are provided on the rotor pressure plate 11. The rotating shaft oil passage 901, the pressure plate oil passage 1102, the magnetic steel slots 1001 and the pressure plate oil holes 1101 are connected in sequence, and the pressure plate oil holes 1101 face the inner surface of the end of the stator core 4 with windings.

[0043] Preferably, Figure 1 and Figure 7 As shown, the pressure plate oil holes 1101 are arranged obliquely on the rotor pressure plate 11 , and the inclination angles of several pressure plate oil holes 1101 are different and all face the end of the stator core 4 with windings.

[0044] Specifically, a shaft oil circuit 901 is set inside the shaft 9, and the cooling oil passes through the pressure plate oil channel 1102 and the magnet groove 1001, and is finally ejected from the pressure plate oil holes 1101 with different inclination angles. When the rotor rotates, the centrifugal force throws the oil to the inner surface of the stator winding end, realizing the integrated cooling function of the shaft oil circuit, synchronously cooling the rotor magnet 12 and the stator winding to avoid overheating of the magnet 12; and the pressure plate oil holes 1101 inclined at multiple angles cover the entire inner surface of the stator end, solving the blind spot problem of traditional oil-throwing cooling; the cooling oil directly contacts the winding end, with high heat dissipation efficiency, significantly reducing the risk of local hot spots.

[0045] Preferably, Figure 1-5 As shown, the oil sleeve is provided with a bypass loop 18 and a plurality of axial flow channels 15 connected to the bypass loop 18. An oil inlet 19 for communication is provided between the bypass loop 18 and the oil passage space 20. The plurality of axial flow channels 15 are respectively connected to a plurality of radial oil holes 13 and a plurality of axial oil holes 14.

[0046] Preferably, Figure 1-5 As shown, a plurality of radial oil holes 13 are distributed in a ring shape on the oil sleeve into a plurality of groups, and each group includes a plurality of radial oil holes 13 arranged at axial intervals.

[0047] Preferably, Figure 1-5 As shown, the end of the oil sleeve is provided with a plurality of protruding rods distributed in a ring shape, and a plurality of axial oil holes 14 are respectively located on the plurality of protruding rods and facing the end surface of the end of the stator core 4 with windings. The axial oil holes 14 on the protruding rods are connected with the axial flow channel 15 through the radial flow channel 16.

[0048] Specifically, a diverter loop 18 and an axial flow channel 15 are provided in the oil jacket. After the cooling oil enters from the oil inlet 19, it is evenly distributed to each axial flow channel 15 through the diverter loop 18, and then ejected through the annular radial oil holes 13 and the axial oil holes 14 on the extension rod. The diverter loop 18 can achieve uniform oil distribution to avoid insufficient local flow. The annular radial oil hole group covers the circumference of the stator core, and the axial oil hole 14 accurately sprays the end face area through the extension rod. The overall structure is compact, the oil circuit is highly integrated, and it is easy to assemble and maintain.

[0049] Preferably, Figure 1-5 As shown, the stator core 4 with windings includes a non-parallel end 401, a stator core 402 and a parallel end 403, and two oil jackets include a non-parallel end oil jacket 3 and a parallel end oil jacket assembly 5. The non-parallel end oil jacket 3 is installed at the non-parallel end 401, and the parallel end oil jacket assembly 5 includes a parallel end oil jacket 5 and an oil ring 6. The parallel end oil jacket 5 and the oil ring 6 are both installed at the parallel end 403.

[0050] Preferably, Figure 4-5 As shown, the parallel end oil sleeve 5 is provided with oil channel ribs 17, axial flow channels 15, diverter loops 18, oil inlets 19 and radial oil holes 13, and the oil ring 6 is provided with axial flow channels 15, axial oil holes 14, radial flow channels 16 and extension rods. The axial flow channels 15 on the parallel end oil sleeve 5 and the axial flow channels 15 on the oil ring 6 can be connected after being installed and connected to each other.

[0051] Preferably, Figure 1 As shown, an oil sleeve stop 204 is provided at the non-parallel end side in the casing 2 , and the non-parallel end oil sleeve 3 is positioned and installed through the oil sleeve stop 204 .

[0052] Preferably, Figure 1 As shown, an oil jacket mounting step surface 205 is provided at the parallel end side in the casing 2, and a first mounting platform 21 and a second mounting platform 22 are respectively provided on the parallel end oil jacket 5 and the oil ring 6. The first mounting platform 21 of the parallel end oil jacket 5 is positioned and mounted on the oil jacket mounting step surface 205, and the first mounting platform 21 of the parallel end oil jacket 5 and the second mounting platform 22 of the oil ring 6 are mounted and connected to each other. Specifically, the first mounting platform 21 and the second mounting platform 22 can be fastened with bolts.

[0053] Specifically, the split oil jacket and oil ring design solves the installation problem of the stator core 4 with winding and the head end. The oil jacket stop 204 and the mounting platform ensure the positioning accuracy of the components and avoid oil path deviation.

[0054] advantage:

[0055] 1. Multi-directional collaborative cooling, comprehensive coverage of heat sources: The stator core is cooled through an "S"-shaped oil circuit, and radial and axial oil holes are used to cool the outer surfaces and end faces of both ends; the multi-angle oil holes of the rotor pressure plate cover the inner surface of the stator end, forming a three-dimensional cooling network of "outer-inner-axial end face", which completely eliminates local high temperatures.

[0056] 2. Structural simplification and process optimization: The oil sleeve assembly replaces the traditional punching die oil channel, reducing manufacturing complexity and cost; the split oil sleeve and oil ring design takes into account both installation convenience and cooling performance, improving assembly efficiency.

[0057] 3. Efficient heat dissipation and improved reliability: The oil circuit space and shunt loop design increase the heat exchange area, improving heat dissipation efficiency by more than 30%; the rotor magnets and stator windings are cooled synchronously, extending the motor life and adapting to high power density conditions.

[0058] 4. Flexible adaptability and scalability: The oil sleeve and oil ring can be customized according to different motor sizes, with strong compatibility; the oil outlet can be equipped with a nozzle to further enhance the cooling effect and meet diverse application needs.

[0059] The present invention solves the pain points of traditional oil-cooled motors such as uneven cooling, complex processes, and local overheating through an innovative multi-directional oil circuit design, split component structure, and rotor-stator collaborative cooling mechanism.

[0060] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An oil-cooled motor with multi-directional stator cooling, characterized in that: include: The motor assembly includes a housing, a stator core with windings, and a rotor assembly installed in the housing. The housing is provided with an oil inlet for the entire machine, an oil outlet for the entire machine, and an oil outlet for the stator core area. An oil sleeve assembly includes two oil sleeves, both of which are located in the casing and are respectively installed at the two ends of the stator core with windings. The stator core with windings, the casing and the space between the two oil sleeves form an oil path space. The oil inlet hole of the whole machine and the oil outlet hole of the stator core area are connected to the oil path space. The oil outlet hole of the stator core area is connected to the oil outlet hole of the whole machine. A plurality of oil channel ribs are provided on opposite sides of the two oil sleeves. The plurality of oil channel ribs are staggered and distributed to form an "S"-shaped oil path in the oil path space. Both oil sleeves are provided with a plurality of radial oil holes and a plurality of axial oil holes that are connected to the oil path space. The radial oil holes face the outer surface of the end of the stator core with windings, and the axial oil holes face the end surface of the end of the stator core with windings.

2. The oil-cooled motor with multi-directional stator cooling according to claim 1, characterized in that: The rotor assembly includes a rotating shaft, a rotor pressure plate, a rotor core segment and a plurality of magnets. The rotor core segment is provided with a plurality of magnet slots, the magnets are installed on the magnet slots, the rotor core segment is installed on the rotating shaft, and the rotor pressure plates are respectively located at both ends of the rotor core segment. A rotating shaft oil circuit is provided in the rotating shaft, and a plurality of pressure plate oil channels and a plurality of pressure plate oil holes are provided on the rotor pressure plate. The rotating shaft oil circuit, the pressure plate oil channel, the magnet slots and the pressure plate oil holes are connected in sequence, and the pressure plate oil holes face the inner surface of the end of the stator core with windings.

3. The oil-cooled motor with multi-directional stator cooling according to claim 2, characterized in that: The pressure plate oil holes are arranged obliquely on the rotor pressure plate, and the inclination angles of the pressure plate oil holes are different and all face the end of the stator core with windings.

4. The oil-cooled motor with multi-directional stator cooling according to claim 1, characterized in that: The oil sleeve is provided with a diverter loop and several axial flow channels connected with the diverter loop. An oil inlet for communication is provided between the diverter loop and the oil passage space. The several axial flow channels are respectively connected with several radial oil holes and several axial oil holes.

5. The oil-cooled motor with multi-directional stator cooling according to claim 4, characterized in that: The radial oil holes are distributed in a ring shape on the oil sleeve to form a plurality of groups, and each group includes a plurality of radial oil holes arranged at an axial distance.

6. The oil-cooled motor with multi-directional stator cooling according to claim 4, characterized in that: The end of the oil sleeve is provided with a plurality of protruding rods distributed in a ring shape, and a plurality of axial oil holes are respectively located on the plurality of protruding rods and face the end surface of the end of the stator core with winding.

7. The oil-cooled motor with multi-directional stator cooling according to claim 1, characterized in that: The stator core with windings includes a non-parallel end, a stator core and a parallel end. The two oil jackets include a non-parallel end oil jacket and a parallel end oil jacket assembly. The non-parallel end oil jacket is installed at the non-parallel end. The parallel end oil jacket assembly includes a parallel end oil jacket and an oil ring. The parallel end oil jacket and the oil ring are both installed at the parallel end.

8. The oil-cooled motor with multi-directional stator cooling according to claim 7, characterized in that: An oil sleeve stop is provided at the non-parallel end side in the casing, and the oil sleeve at the non-parallel end is positioned and installed through the oil sleeve stop.

9. The oil-cooled motor with multi-directional stator cooling according to claim 7, characterized in that: An oil sleeve mounting step surface is provided in the casing at the parallel head end side, and a first mounting platform and a second mounting platform are provided on the parallel head end oil sleeve and the oil ring respectively. The first mounting platform of the parallel head end oil sleeve is positioned and mounted on the oil sleeve mounting step surface, and the first mounting platform of the parallel head end oil sleeve and the second mounting platform of the oil ring are mounted and connected to each other.

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