Liquid-cooled hub motor

Abstract

The utility model discloses a liquid-cooled hub motor, and relates to the technical field of hub motors. The rotor is used for driving the rim to rotate; the stator support is rotationally arranged on the inner circumferential side face of the rotor, and a stator is arranged on the outer circumferential side face of the stator support; and the cooling flow channel is integrally in a wave shape and is arranged in the stator support in a surrounding mode, an inlet channel is formed in the first end of the cooling flow channel, and an outlet channel is formed in the second end of the cooling flow channel. According to the liquid-cooled hub motor, the technical problem that the hub motor is overheated when the hub motor is continuously used at overpower in the prior art is solved, the cooling liquid is circularly input into the cooling flow channel through the inlet channel, heat on the stator support is taken away, and the performance of the hub motor can still be kept unchanged when the hub motor is continuously used at overpower. And the overall structure of the cooling flow channel accords with fluid mechanics, and the cooling liquid does not form turbulent flow and vortex when flowing in the cooling flow channel, so that the energy consumption required for driving the cooling liquid to flow can be reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to wheel hub motor technical field, especially a kind of liquid-cooled wheel hub motor. BACKGROUND

[0002] Wheel hub motor adopts outer rotor structure motor, rotor part is combined into an organic whole with rim.The stator component is wrapped by the whole of shell and rotor component, and the stator component is the heat source of motor heat generation.Due to the stator component and shell no contact intermediate air barrier heat rapid conduction, resulting in motor temperature rising continuously inhibits the sustained performance of motor, and under super power continuous use, wheel hub motor can appear overheating condition, resulting in wheel hub motor performance decline and demagnetization phenomenon.

[0003] In the prior art, the motor performance is in the best range by motor liquid cooling technology, and the liquid-cooled motor technology is to add cooling liquid directly in the motor, an oil-gas filtering device is installed in the motor, the oil-gas filtering device is connected with a gas guide pipe, when the stator component is heated, the cooling liquid absorbs heat, and heat conduction is carried out through the cooling liquid contacting the shell, however, the stator flow channel structure is completed by die casting processing, the die casting alloy material itself has pores, and the pore leakage probability is high after processing, in this case, the flow channel formed by the die casting alloy material is easy to appear cooling liquid leakage when the heat and cold are alternately aged, thereby causing the performance of the whole machine to be reduced and damaged. Therefore, a liquid-cooled wheel hub motor for solving the above problems is proposed. SUMMARY

[0004] The utility model aims at providing a kind of liquid-cooled wheel hub motor, solve the technical problem that wheel hub motor appears overheating condition under super power continuous use in prior art.

[0005] To achieve the above object, the utility model provides a kind of liquid-cooled wheel hub motor, comprising:

[0006] Rim;

[0007] Rotor, is located in the inner circumferential side of the rim, for driving rim synchronous rotation;

[0008] Stator support, rotationally arranged on the inner circumferential side of the rotor, the outer circumferential side of the stator support is provided with stator, and the stator is used to drive the rotor to rotate;

[0009] Cooling flow channel, it is integrally arranged in the interior of the stator support in wave shape, the first end of the cooling flow channel is provided with inlet channel for inputting cooling liquid into the cooling flow channel, and the second end of the cooling flow channel is provided with outlet channel for discharging cooling liquid in the cooling flow channel.

[0010] Preferably, the inner array of the stator support is arranged with a plurality of first assembly rods, two adjacent first assembly rods combine to form a first U-shaped slot, the side of the stator support is provided with a cooling flow channel cover plate, the cooling flow channel cover plate is arranged with a plurality of second assembly rods near one side of the stator support, two adjacent second assembly rods combine to form a second U-shaped slot, and each first U-shaped slot is staggered and connected with one second U-shaped slot to form the cooling flow channel when the cooling flow channel cover plate is connected with the stator support.

[0011] Preferably, when the cooling flow channel cover plate is connected with the stator support, the first assembly rod is not in contact with the side of the second U-shaped slot, and the second assembly rod is not in contact with the side of the first U-shaped slot.

[0012] Preferably, one side of the stator support provided with the cooling flow channel cover plate is provided with an inlet and outlet flow channel cover plate, and the inlet and outlet flow channel cover plate is used for sealing the inlet channel and the outlet channel.

[0013] Preferably, the side of the inlet and outlet flow channel cover plate is provided with an inlet liquid channel and an outlet liquid channel, the inlet liquid channel is connected with the cooling flow channel and the inlet channel, and the outlet liquid channel is connected with the cooling flow channel and the outlet channel.

[0014] Preferably, the side of the stator support away from the inlet and outlet flow channel cover plate is provided with a water nozzle pressing plate, the side of the water nozzle pressing plate near the stator support is provided with a sealing pressing plate, the sealing pressing plate is used for sealing the inlet channel and the outlet channel, and the water nozzle pressing plate is provided with an inlet water pipe and an outlet water pipe, the inlet water pipe is connected with the inlet channel, and the outlet water pipe is connected with the outlet channel.

[0015] Preferably, one side of the stator support is provided with a flat end cover, and the flat end cover is used for protecting the internal structure of the hub.

[0016] Preferably, the axis position of the stator support is provided with an assembly hole, a motor shaft is coaxially arranged in the assembly hole, and the motor shaft is rotatably connected with the rotor.

[0017] Preferably, the both ends of the motor shaft are provided with bearings, and the bearings are fixedly connected with the stator support.

[0018] Preferably, the side of the stator support opposite to the flat end cover is provided with a brake end cover, and the brake end cover is drivingly connected with the rotor.

[0019] With respect to the above background, the liquid-cooled hub motor provided by the present application has the following beneficial effects:

[0020] (1) The in-process heat generated by the stator component is transferred to the stator support through the stator, the cooling liquid is input into the cooling flow channel through the import channel, the cooling liquid circulates from one end of the cooling flow channel to the other end of the cooling flow channel, and the heat on the stator support is taken away, so that the overheat and demagnetization of the wheel hub motor are effectively prevented, the performance of the wheel hub motor can remain unchanged under the condition of over-power continuous use, compared with directly adding cooling liquid in the motor, the sealing effect of the cooling flow channel arranged in the stator support on the cooling liquid is better, the heat dissipation effect of the stator component is ensured, and the cooling liquid leakage is avoided, so that the performance of the wheel hub motor is not affected, and the practicality is better.

[0021] (2) The cooling flow channel is arranged in the interior of the stator support in a whole wave shape, the structure of the cooling flow channel meets fluid mechanics, when the cooling liquid flows in the cooling flow channel, the change of the speed and the pressure is relatively relatively flat, and local high-speed area and low-pressure area are not easily generated like at right angles or sharp corners, so that the formation of turbulence and vortex is avoided, the resistance of the cooling liquid in the cooling flow channel is smaller, the energy consumption required for driving the cooling liquid to flow is reduced, and the power requirement of the pump can be reduced. On the other hand, the wave-shaped cooling flow channel can improve the contact area of the cooling liquid and the stator support, so that the cooling liquid is in full contact with the stator support, and the heat dissipation effect of the stator component is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and those skilled in the art can obtain other drawings according to the provided drawings without creating any creative labor.

[0023] Figure 1 A perspective view of the liquid-cooled wheel hub motor provided by the embodiment of the present application is provided.

[0024] Figure 2 A cross-sectional view of the liquid-cooled wheel hub motor provided by the embodiment of the present application is provided.

[0025] Figure 3 An explosion view of the liquid-cooled wheel hub motor provided by the embodiment of the present application is provided.

[0026] Figure 4 A partial cross-sectional view of the liquid-cooled wheel hub motor provided by the embodiment of the present application is provided.

[0027] Figure 5 A perspective view of the liquid-cooled wheel hub motor provided by the embodiment of the present application is provided.

[0028] Figure 6 A flow direction schematic view of the cooling liquid in the cooling flow channel provided by the embodiment of the utility model;

[0029] Figure 7 A whole flow direction schematic view of the cooling liquid in the stator support provided by the embodiment of the utility model;

[0030] Figure 8 A plane schematic view of the cooling flow channel after being unfolded in plane provided by the embodiment of the utility model.

[0031] Specifically, 1 - rotor;2 - stator support;201 - import passage;202 - export passage;203 - first assembly rod;204 - first U-shaped groove;3 - stator;4 - cooling flow channel;5 - cooling flow channel cover plate;501 - second assembly rod;502 - second U-shaped groove;503 - sealing ring;6 - water nozzle pressure plate;7 - import and export flow channel cover plate;701 - liquid inlet passage;702 - liquid outlet passage;8 - flat end cover;9 - motor shaft;10 - bearing;11 - brake end cover;12 - sealing pressure plate;13 - water inlet pipe;14 - water outlet pipe;15 - fit cross structure. DETAILED DESCRIPTION

[0032] The technical scheme in the embodiments of the utility model will be described clearly and completely below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0033] In order to make those skilled in the art better understand the technical scheme of the utility model, the utility model will be further described in detail below in conjunction with the drawings and specific embodiments.

[0034] As Figure 1 , Figure 2 and Figure 3 shown, to realize the above-mentioned purpose, the utility model provides a kind of liquid cooling hub motor, it include: wheel rim and the rotor 1 and stator 3 being set on wheel rim, wherein, rotor 1 is integrally arranged in the inner circumferential side surface of wheel rim, and rotor 1 is synchronous rotation with wheel rim.

[0035] The inner circumferential surface of the rotor 1 is rotatably provided with a stator support 2, and the outer circumferential surface of the stator support 2 is provided with a stator 3 for driving the rotor 1 to rotate. Preferably, the stator 3 is a silicon steel sheet stator 3, which has high magnetic conductivity and low hysteresis characteristics, can effectively reduce the magnetic field loss during the operation of the motor, improve the efficiency of the motor, and the high magnetic conductivity of the silicon steel sheet can enhance the magnetic field strength of the stator 3 core, generate a stronger magnetic field under the same current, thereby improving the output power and efficiency of the motor, on the other hand, it has good supporting effect, increases the overall structural strength of the hub motor. In addition, the stator 3 is provided with a stator 3 winding, and after the stator 3 winding is connected to three-phase alternating current, a rotating magnetic field is generated, and through the interaction between the rotating magnetic field and the rotor 1, the stator 3 winding converts electrical energy into mechanical energy to drive the rotor 1 to operate.

[0036] It should be noted that the cooling flow channel 4 is arranged in the inner part of the stator support 2, and the cooling flow channel 4 is in a whole wave shape, and the cooling flow channel 4 is arranged in the inner part of the stator support 2 in a whole wave shape, which conforms to fluid mechanics. When the cooling liquid flows in the cooling flow channel 4, the changes of speed and pressure are relatively smooth, and local high-speed areas and low-pressure areas are not easily formed like at right angles or sharp corners, avoiding the formation of turbulence and vortex, and the cooling liquid in the cooling flow channel 4 is subjected to smaller resistance, reducing the energy consumption required to drive the cooling liquid to flow, thereby reducing the power requirement of the pump.

[0037] In use, one end of the cooling flow channel 4 is provided with an inlet channel 201, and the cooling liquid is input into the cooling flow channel 4 through the inlet channel 201, and the other end of the cooling flow channel 4 is provided with an outlet channel 202, and the cooling liquid in the cooling flow channel 4 is discharged through the outlet channel 202, so that the cooling liquid forms a circulation in the cooling flow channel 4. After the heat generated by the stator 3 component is transmitted to the stator support 2 through the stator 3, the heat on the stator support 2 is taken away, which has a heat dissipation effect on the stator 3 component, effectively prevents the hub motor from overheating and demagnetization, and makes the performance of the hub motor remain unchanged under the condition of continuous use of super power.

[0038] In one embodiment of the utility model, the inside array of stator support 2 is equipped with several first assembly bars 203, the first assembly bar 203 is integrally formed with stator support 2, two adjacent first assembly bars 203 are combined to form a first U-shaped groove 204, the first assembly bar 203 extends along the axis direction of stator support 2 to a certain length, so that the first U-shaped groove 204 has a certain width, the side surface of stator support 2 is provided with cooling flow channel cover plate 5, the side surface of cooling flow channel cover plate 5 close to stator support 2 is arrayed with several second assembly bars 501, two adjacent second assembly bars 501 are combined to form a second U-shaped groove 502, the second assembly bar 501 extends along the axis direction of cooling flow channel cover plate 5 to a certain length, so that the second U-shaped groove 502 has a certain width, when cooling flow channel cover plate 5 is connected with stator support 2, each first U-shaped groove 204 is staggered with a second U-shaped groove 502 to form a wave-shaped cooling flow channel 4, and the cooling flow channel 4 is arranged in the inside of stator support 2 in a ring shape.

[0039] It should be noted that when cooling flow channel cover plate 5 is connected with stator support 2, the side surface of first assembly bar 203 and second U-shaped groove 502 do not contact each other, and the side surface of second assembly bar 501 and first U-shaped groove 204 do not contact each other, which effectively ensures that the two ends of cooling flow channel 4 are always kept in communication.

[0040] In addition, compared with directly adding cooling liquid in the motor, the cooling flow channel 4 arranged in the inside of stator support 2 has better sealing effect on the cooling liquid, which can ensure the heat dissipation effect of stator 3 and prevent the cooling liquid from leaking, so as to not affect the performance of the hub motor and have better practicability.

[0041] In one embodiment of the utility model, the side of stator support 2 provided with cooling flow channel cover plate 5 is provided with inlet and outlet flow channel cover plate 7, after inlet and outlet flow channel cover plate 7 is buckled on the side surface of stator support 2, inlet and outlet flow channel cover plate 7 can seal inlet channel 201 and outlet channel 202, at the same time, inlet and outlet flow channel cover plate 7 is provided with liquid inlet channel 701 and liquid outlet channel 702 on the side surface, after inlet and outlet flow channel cover plate 7 is buckled on the side surface of stator support 2, liquid inlet channel 701 and liquid outlet channel 702 do not communicate with each other, liquid inlet channel 701 communicates cooling flow channel 4 and inlet channel 201, cooling liquid sequentially passes through inlet channel 201 and liquid inlet channel 701 and then enters the heat exchange channel, liquid outlet channel 702 communicates cooling flow channel 4 and outlet channel 202, after absorbing the heat of stator support 2, the cooling liquid is discharged from the heat exchange channel to outlet channel 202, sequentially discharged from outlet channel 202 and liquid outlet channel 702, and the single cycle of the cooling liquid is completed.

[0042] In addition, the water nozzle pressing plate 6 is arranged on the side of the stator support 2 away from the inlet-outlet flow channel cover plate 7, the water inlet pipe 13 and the water outlet pipe 14 are arranged on the water nozzle pressing plate 6, the water inlet pipe 13 is connected with the inlet channel 201, the water outlet pipe 14 is connected with the outlet channel 202, the water inlet pipe 13 is connected with a water pump (not shown in the figure), the water outlet pipe 14 is connected with a water storage tank (not shown in the figure), the water pump pumps the cooling liquid in the water storage tank and delivers it to the inlet channel 201, and then the cooling liquid enters the heat exchange channel through the inlet channel 201 and the liquid inlet channel 701 in sequence, and the cooling liquid discharged from the heat exchange channel is discharged to the water storage tank through the liquid outlet channel 702, the outlet channel 202 and the water outlet pipe 14 in sequence. Preferably, a filtering device is arranged in the water storage tank, which can filter the cooling liquid discharged from the cooling flow channel 4, and the cooling liquid can be recycled, thereby saving the cost of hub motor heat dissipation.

[0043] In addition, the sealing pressing plate 12 is arranged on the side of the water nozzle pressing plate 6 close to the stator support 2, the inlet channel 201 and the outlet channel 202 are sealed by the sealing pressing plate 12, the water inlet pipe 13 is sealingly connected with the inlet channel 201 through the sealing pressing plate 12, the water outlet pipe 14 is sealingly connected with the outlet channel 202 through the sealing pressing plate 12, and the leakage of the cooling liquid during circulation is prevented, and preferably, rubber sealing pads (not shown in the figure) are arranged on the inner side of the sealing pressing plate 12, so as to enhance the sealing strength of the sealing pressing plate 12 and the stator support 2. At the same time, the sealing ring 503 is arranged on the side of the cooling flow channel cover plate 5 close to the stator support 2, the side surface of the sealing ring 503 is attached to the side surface of the cooling flow channel cover plate 5, and the sealing property of the connection between the cooling flow channel cover plate 5 and the stator support 2 is further enhanced, so as to prevent the leakage of the cooling liquid from the cooling flow channel 4 and improve the safety of the hub motor during operation.

[0044] It should be noted that the fitting cross structure 15 is arranged on the stator support 2 and the cooling flow channel cover plate 5, two mutually unconnected through holes are arranged at the position of the fitting cross structure 15, one through hole is used for connecting the inlet channel 201 and the liquid inlet channel 701, and the other through hole is used for connecting the outlet channel 202 and the liquid outlet channel 702, the two fitting cross structures 15 are matched with each other, which can prevent incorrect installation during assembly and improve the assembly efficiency of the cooling flow channel cover plate 5 on the stator support 2. At the same time, the first U-shaped groove 204 and the second U-shaped groove 502 are accurately docked, the parts of the flow channel are uniformly distributed, and the cooling liquid can stably circulate in the cooling flow channel 4.

[0045] In one embodiment of the utility model, the side of the stator support 2 provided with the water nozzle pressing plate 6 is provided with a flat end cover 8, the flat end cover 8 is connected with the rim through bolts, the internal structure of the hub is protected through the flat end cover 8, and the safety of the hub during operation is improved.

[0046] In one embodiment of the utility model, the assembly hole is arranged at the axis position of stator support 2, motor shaft 9 is arranged coaxially in the assembly hole, motor shaft 9 is rotatably connected with rotor 1, and motor shaft 9 is fixedly connected with stator support 2, that is, motor shaft 9 cannot rotate relative to stator support 2, after the winding of stator 3 drives rotor 1 to rotate, rotor 1 drives the rim to move, thereby driving the car to travel.In addition, bearings 10 are arranged at the two ends of motor shaft 9, and the bearings 10 are rotatably connected with the rim, and when the rim is driven to move by rotor 1, the bearings 10 can ensure that the rim stably rotates on the motor shaft 9.

[0047] In one embodiment of the utility model, brake end cover 11 is arranged on the side opposite to stator support 2 and flat end cover 8, brake end cover 11 is drivingly connected with rotor 1, and brake end cover 11 is connected with bearings 10, the correct position of bearings 10 on motor shaft 9 is limited through brake end cover 11, the movement of bearings 10 along the axis direction of motor shaft 9 is prevented, and the stability of the rim rotating on motor shaft 9 is further improved.On the other hand, brake end cover 11 can prevent dust and other external substances from entering the hub motor, keep the hub motor internal components clean and lubricated, and at the same time provide support for the brake system to ensure its stable operation.

[0048] In one embodiment of the utility model, water inlet pipe 13 and water outlet pipe 14 are connected with a liquid flow direction conversion device, the functions of water inlet pipe 13 and water outlet pipe 14 are flexibly converted according to the steering of the hub, that is, the direction of the cooling liquid flowing in cooling flow channel 4 is changed, the flowing direction of the cooling liquid in stator support 2 is opposite to the direction of stator support 2 rotating with the hub, thereby further reducing the resistance of the cooling liquid in cooling flow channel 4 and reducing the power requirement of the pump.

[0049] When the utility model is used, the temperature of the coil on stator 3 rises, and the heat is transferred to stator support 2 in the form of heat transfer, the water pump sucks the cooling liquid in the water storage tank and delivers it to the inlet channel 201, the cooling liquid enters the heat exchange channel in turn through the inlet channel 201 and the liquid inlet channel 701, the heat on stator support 2 is transferred to the cooling liquid, the cooling liquid is discharged from the heat exchange channel to the outlet channel 202, and is discharged from the outlet channel 202, the liquid outlet channel 702 and the water outlet pipe 14 to the water storage tank in turn, and the cooling liquid forms a cycle in the cooling flow channel 4.

[0050] In summary, the cooling liquid is circulated into the cooling flow channel 4 through the import channel 201 to take away the heat on the stator support 2, so that the performance of the wheel hub motor can remain unchanged under the use of super power. Moreover, the cooling flow channel 4 is in a whole wave shape and is arranged around the inside of the stator support 2, so that the sealing effect of the cooling liquid is better, and the leakage of the cooling liquid does not occur. The structure of the cooling flow channel 4 conforms to the fluid mechanics, so that the cooling liquid does not form turbulence and vortex when flowing in the cooling flow channel 4, the resistance of the cooling liquid in the cooling flow channel 4 is smaller, the energy consumption required for driving the cooling liquid to flow is reduced, and the power requirement of the pump can be reduced.

[0051] It should be noted that the relational terms herein such as first and second, and the like, are used solely to distinguish one entity from another, without necessarily requiring or implying any actual relationship or order between or among the entities.

[0052] The principles and implementation modes of the present application are described by applying specific examples herein, and the above description of the examples is only for helping to understand the method and core idea of the present application. It should be pointed out that, for ordinary skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the present application.

Claims

1. A liquid-cooled wheel hub motor, characterized by, The utility model relates to a kind of motorized wheel, including: Wheel rim; Rotor, it is located in the inner circumferential side of the wheel rim, for driving wheel rim synchronous rotation; Stator support, rotation is arranged in the inner circumferential side of the rotor, the outer circumferential side of the stator support is provided with stator, the stator is used to drive the rotor rotation; Cooling flow channel, it is integrally arranged in the inside of the stator support in wave shape, the first end of the cooling flow channel is provided with inlet channel for inputting cooling liquid into the cooling flow channel, the second end of the cooling flow channel is provided with outlet channel for discharging cooling liquid in the cooling flow channel.

2. The liquid-cooled wheel motor of claim 1, wherein, The inside of the stator support is arranged with a plurality of first assembly rods, and two adjacent first assembly rods are combined to form a first U-shaped groove, and the side of the stator support is provided with a cooling flow channel cover plate, the side of the cooling flow channel cover plate close to the stator support is arranged with a plurality of second assembly rods, and two adjacent second assembly rods are combined to form a second U-shaped groove, and when the cooling flow channel cover plate is connected to the stator support, each first U-shaped groove is staggered to a second U-shaped groove to form the cooling flow channel.

3. The liquid-cooled wheel motor of claim 2, wherein, When the cooling flow channel cover plate is connected to the stator support, the first assembly rod and the side of the second U-shaped groove are not in contact with each other, and the second assembly rod and the side of the first U-shaped groove are not in contact with each other.

4. The liquid-cooled wheel motor of claim 1, wherein, The side of the stator support provided with the cooling flow channel cover plate is provided with an inlet and outlet flow channel cover plate, and the inlet and outlet flow channel cover plate is used to seal the inlet channel and the outlet channel.

5. The liquid-cooled wheel motor of claim 4, wherein, The side of the inlet and outlet flow channel cover plate is provided with an inlet channel and an outlet channel, the inlet channel is connected to the cooling flow channel and the inlet channel, and the outlet channel is connected to the cooling flow channel and the outlet channel.

6. The liquid-cooled wheel motor of claim 5, wherein, The side of the stator support away from the inlet and outlet flow channel cover plate is provided with a water nozzle pressing plate, the side of the water nozzle pressing plate close to the stator support is provided with a sealing pressing plate, the sealing pressing plate is used to seal the inlet channel and the outlet channel, and the water nozzle pressing plate is provided with an inlet pipe and an outlet pipe, the inlet pipe is connected to the inlet channel, and the outlet pipe is connected to the outlet channel.

7. A liquid-cooled wheel hub motor according to any one of claims 1-6, characterized in that, The side of the stator support is provided with a flat end cover, and the flat end cover is used to protect the internal structure of the hub.

8. The liquid-cooled wheel motor of claim 7, wherein, The axis position of the stator support is provided with an assembly hole, and a motor shaft is coaxially arranged in the assembly hole, and the motor shaft is rotatably connected to the rotor.

9. The liquid-cooled wheel motor of claim 8, wherein, The both ends of the motor shaft are provided with bearings, and the bearings are fixedly connected to the stator support.

10. The liquid-cooled wheel motor of claim 9, wherein, The side of the stator support opposite to the flat end cover is provided with a brake end cover, and the brake end cover is drivingly connected to the rotor.

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