A motor with a rotor cooling structure and a vehicle using the motor

Abstract

The application provides a motor with a rotor cooling structure and a vehicle applying the motor, and belongs to the technical field of motor cooling. The motor is provided with a first cylinder body and a second cylinder body corresponding to the two end portions of the rotor in the axial direction, both of which have a cooling cavity for storing cooling liquid and are connected through a cooling flow channel; a piston is slidingly assembled in the cylinder body along the radial direction of the rotor, and the piston separates the inner cavity of the cylinder body to form the cooling cavity and a liquid-free cavity; an elastic member is arranged in the liquid-free cavity, and the elastic member applies an elastic force to the corresponding piston to force the piston to move towards the central axis of the motor rotor. During variable-speed rotation of the motor rotor, the centrifugal force and the elastic force applied to the first piston act cooperatively to make the piston reciprocate, so that the cooling liquid is discharged and sucked into the cooling cavity of the first cylinder body, and then the cooling liquid is driven to flow back and forth between the cooling cavities of the first cylinder body and the second cylinder body, thereby solving the problems of insufficient internal cooling of the motor and the need for external facilities to complete the circulation.

Description

Technical Field

[0001] This invention relates to an electric motor with a rotor cooling structure and a vehicle using the electric motor, belonging to the field of electric motor cooling technology. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the drive motor, as the heart of the power system of new energy vehicles, has increasingly smaller requirements in terms of size and weight, while the power density of the drive motor is required to be higher and higher. Therefore, more and more motors are developing towards high speed, achieving high power through high speed and achieving deceleration and torque increase to drive the vehicle by matching a single reducer.

[0003] One significant issue brought about by the increasing speed of electric motors is the temperature rise of the rotor. The heat generated by high-speed friction between the rotor's outer circumference and the internal air, as well as the heat generated by the rotor core and magnets, increases substantially, posing a risk to the safe operation of the rotor, especially the magnets. Most existing motors use water-cooled permanent magnet motors, with a heat dissipation path of "stator winding – stator core – casing – coolant," relying primarily on the coolant flowing in the casing's water channels to remove the heat generated by the motor. Because the coolant in a water-cooled motor cannot directly contact the heat-generating parts inside the motor (windings, stator and rotor cores, etc.), it is an indirect heat dissipation method. For motors operating at high speed, high power, and high torque for short periods, the internal heat cannot be cooled in time, resulting in high temperatures in the motor windings, core, and magnets. To address the problem of high temperature rise in the internal windings and core of drive motors under short-term high power and high torque conditions, the industry has researched many types of oil-cooled motors, mainly divided into two categories based on the cooling location: stator oil-cooled and rotor oil-cooled.

[0004] Since the motor stator does not rotate, oil cooling is relatively simple to achieve. Currently, there are mainly two methods: stator oil injection cooling and stator oil channel cooling. However, due to the high-speed rotation of the rotor, achieving dynamic oil cooling through the oil channels is more complex. Based on the principle, it is mainly divided into two categories: rotor oil churning and rotor oil splashing. The rotor oil churning method involves injecting a certain volume of cooling oil into the internal cavity of the motor. When the motor rotates, the oil churning structure of the rotor end ring agitates the internal cooling oil, and the splashing of the cooling oil cools the motor rotor and stator. The advantage of this method is that the oil cooling circulation is achieved entirely by the rotation of the rotor, without the need for external force or other structures, making it simple and convenient. However, the disadvantages are that the cooling effect is insufficient, easily affected by the speed, and increases some mechanical losses. The rotor oil splashing method is achieved through a hollow shaft and rotor oil channels. The advantage of this method is that the cooling oil can closely contact the inside of the rotor through the oil channels, resulting in a more sufficient cooling effect. However, the disadvantage is that after the oil splashes out from the hollow shaft to the rotor oil channels, an external oil pump needs to provide a certain pressure to collect the oil again to complete the circulation.

[0005] Patent CN 106787452 A provides a rotor oil-throwing solution. Specifically, the motor shaft is machined into a hollow shaft, and a cooling channel communicating with the shaft is machined in the rotor core or rotor pressure plate. Cooling oil is injected into the motor through the hollow shaft, and the centrifugal force of the motor rotation throws the oil into the oil channels of the rotor core or pressure plate to cool the motor rotor. The disadvantage of this solution is that the machining of the shaft and the oil channels of the core is relatively complex, and the cooling effect is overly dependent on the motor speed. At low speeds, the cooling effect is not ideal due to the small centrifugal force. Although an external oil pump can be added to ensure that there is still a certain pressure to guarantee the flow of cooling oil at low speeds, this undoubtedly increases the difficulty of external manufacturing.

[0006] Patent application CN 112421833 A discloses an oil-cooled rotor structure. The rotor cooling oil is connected to the rotor oil guide groove structure and the weight-reducing hole inside the rotor through the blind hole of the rotor shaft to achieve the cooling of the rotor. This type of solution can make good use of the rotor weight reduction design to achieve oil cooling, but it also requires an external oil pump to provide external force to complete the circulation of cooling oil. Summary of the Invention

[0007] The purpose of this invention is to provide an electric motor with a rotor cooling structure and a vehicle using the electric motor, in order to solve the problems of insufficient internal cooling of the motor and the need for external facilities to help complete the cycle.

[0008] To achieve the above objectives, the present invention provides a motor with a rotor cooling structure. A first cylinder and a second cylinder are respectively disposed at two axial ends of the motor rotor, each having a cooling chamber for storing coolant and connected by a cooling channel. A first piston is radially and slidably mounted within the first cylinder along the motor rotor, dividing the inner cavity of the cylinder into the cooling chamber and a liquid-free chamber. A first elastic element is disposed within the liquid-free chamber, applying an elastic force to the corresponding piston, forcing it to move towards the rotational axis of the motor rotor. During the rotation of the motor rotor, the centrifugal force and the elastic force acting on the first piston work together to drive the piston to reciprocate, thereby discharging and drawing in coolant from the cooling chamber of the first cylinder, and driving the coolant to flow back and forth between the cooling chambers of the first and second cylinders. The second cylinder has the same structure and is radially mounted along the motor rotor, but in the opposite direction to the first cylinder, resulting in the cooling chamber of the first cylinder discharging and drawing in coolant while the cooling chamber of the second cylinder simultaneously draws in and discharges coolant.

[0009] The beneficial effects of this invention are: the coolant flow circulation is achieved solely by the rotor speed through structural design, which is simple and convenient; the coolant and rotor core are in full contact, resulting in good cooling effect; the pressure in the two cylinders is superimposed in the same direction, increasing the single flow rate of the coolant and enhancing the cooling effect.

[0010] Furthermore, in the aforementioned motor, the first piston or the second piston has a blocking position that blocks the corresponding connecting hole during its stroke; when the motor rotor speed is lower than a set value, the first piston or the second piston remains at the blocking position.

[0011] The beneficial effect of this is that the blocking position corresponds to the motor rotor speed. When the rotor speed is lower than the set value, the piston blocks the connecting hole, thereby realizing that the rotor cooling function is not activated at low speeds, and the rotor cooling function is activated only after the speed reaches a certain level, ensuring the stability of the motor at low speeds.

[0012] Furthermore, in the aforementioned motor, the first piston and / or the second piston have protrusions extending into the cooling chamber on their surfaces facing the cooling chamber, avoiding the connecting hole. The outer surface of these protrusions is inclined and faces the connecting hole.

[0013] The beneficial effects of this are: the protrusion allows the piston to more fully discharge the coolant from the cooling chamber as it moves toward the cooling chamber; the inclined surface of the protrusion facing the connecting hole reduces the resistance to coolant flow, both of which ensure the cooling effect.

[0014] Furthermore, in the aforementioned motor, the liquid-free chamber of the first cylinder is positioned away from the central axis of rotation of the motor rotor, while the liquid-free chamber of the second cylinder is positioned close to the central axis of rotation of the motor rotor. The cooling channel is inclined within the motor rotor, and the distance from the end connecting to the cooling chamber of the first cylinder to the central axis of rotation of the motor rotor is approximately the same as the distance from the end connecting to the cooling chamber of the second cylinder to the central axis of rotation of the motor rotor.

[0015] Furthermore, in the aforementioned motor, the first elastic element is a compression spring, disposed within the liquid-free chamber of the first cylinder; the second elastic element is a tension spring, disposed within the liquid-free chamber of the second cylinder.

[0016] Furthermore, in the aforementioned motor, the first cylinder block, the second cylinder block, and the corresponding cooling channels constitute a heat dissipation unit, and at least two heat dissipation units are evenly arranged on the motor rotor. The number of heat dissipation units is even, and the first cylinder block and the second cylinder block are spaced apart on either end of the motor rotor's axial direction.

[0017] The beneficial effects of this are: the cooling units on the motor rotor are arranged in opposite directions (the first and second cylinders define the direction of the cooling units), and the coolant flows in opposite directions in adjacent cooling units during operation, which ensures the balance of weight at both ends of the motor as much as possible, enhances the stability of rotor rotation, and ensures smooth motor operation.

[0018] Furthermore, the present invention also provides a vehicle in which a first cylinder and a second cylinder are respectively provided at two ends of the motor rotor along the axial direction. Each cylinder has a cooling chamber for storing coolant and is connected to the first cylinder via a cooling channel. A first piston is radially and slidably mounted in the first cylinder along the motor rotor. The first piston divides the inner cavity of the cylinder into the cooling chamber and a liquid-free chamber. A first elastic element is provided in the liquid-free chamber, which applies an elastic force to the corresponding piston, forcing it to move towards the rotational axis of the motor rotor. During the rotation of the motor rotor, the centrifugal force and the elastic force acting on the first piston work together to drive the piston to reciprocate, thereby discharging and drawing in coolant from the cooling chamber of the first cylinder, and driving the coolant to flow back and forth between the cooling chambers of the first and second cylinders. The second cylinder has the same structure and is radially mounted along the motor rotor, but in the opposite direction to the first cylinder, causing the cooling chamber of the first cylinder to discharge and draw in coolant while the cooling chamber of the second cylinder simultaneously draws in and discharges coolant. The first or second piston has a sealing position on its stroke to block the corresponding connecting hole; when the motor rotor speed is lower than a set value, the first or second piston remains at the sealing position. The first piston and / or the second piston have protrusions extending into the cooling cavity on their surfaces facing the cooling cavity, avoiding the connecting hole. The outer surface of these protrusions is inclined and faces the connecting hole. The liquid-free cavity of the first cylinder is located away from the central axis of rotation of the motor rotor, while the liquid-free cavity of the second cylinder is located close to the central axis of rotation of the motor rotor. The cooling channels are inclined within the motor rotor, and the distance from the end connecting to the cooling cavity of the first cylinder to the central axis of rotation of the motor rotor is approximately the same as the distance from the end connecting to the cooling cavity of the second cylinder to the central axis of rotation of the motor rotor. The first cylinder, the second cylinder, and the corresponding cooling channels constitute a heat dissipation unit, and at least two heat dissipation units are evenly arranged on the motor rotor. The number of heat dissipation units is even, and the first cylinder and the second cylinder are spaced apart at either end of the motor rotor's axial direction.

[0019] The beneficial effects of this invention are as follows: the coolant flow circulation is achieved solely through the rotor speed via structural design, which is simple and convenient; the coolant and rotor core are in full contact, resulting in good cooling effect; the protrusion facilitates more thorough discharge of coolant from the cooling chamber as the piston moves toward it; the inclined surface of the protrusion facing the connecting hole reduces the resistance to coolant flow, both of which ensure cooling effect; the heat dissipation units on the motor rotor are arranged in opposite directions (the first and second cylinders define the direction of the heat dissipation units), and the coolant flows in opposite directions in adjacent heat dissipation units during operation, which maximizes the balance of weight at both ends of the motor, enhances the stability of rotor rotation, and ensures smooth motor operation. Attached Figure Description

[0020] Figure 1 A cross-sectional view of the motor rotor cooling device provided by the present invention; Figure 2A plan view of the motor rotor cooling device provided for this invention (and) Figure 1 (Same perspective) Figure 3 This is a schematic diagram of the rotor end face with a motor rotor heat dissipation unit installed in an embodiment of the present invention; Figure 4 This is a schematic diagram of the operation of the heat dissipation unit for increasing motor speed in an embodiment of the present invention (the figure shows half of the cross-section of the motor rotor). Figure 5 This is a schematic diagram of the operation of the heat dissipation unit for reducing motor speed in an embodiment of the present invention (the figure shows half of the cross-section of the motor rotor). Figure 6 This is a schematic diagram of a motor structure with an added rotor cooling structure in an embodiment of the present invention.

[0021] In the diagram, 101 is an elastic element, 1011 is a compression spring, 1012 is a tension spring, 102 is a liquid-free chamber, 103 is a piston, 104 is a cooling chamber, 105 is a connecting plate, 106 is a connecting hole, 107 is a cylinder block, 1071 is the first cylinder block, 1072 is the second cylinder block, 108 is a mounting hole, and 109 is an oil filling hole. 201 is the motor spindle, 202 is the rotor core, 203 is the cooling channel, and 204 is the motor stator. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical principles and practical applications of this invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0023] Centrifugal force on an object in circular motion F The calculation formula is (1) in, The mass of an object moving in a circular motion is represented by the unit kilogram (kg). Angular velocity represents the motion of an object, and its unit is radians per second (rad / s). It represents the radius of the circumference of an object, and the unit is meters (m).

[0024] As can be seen from equation (1), the motor rotor and other parts contained in the rotor will generate centrifugal force when rotating, and the centrifugal force is proportional to the rotation speed and the radius of rotation.

[0025] The magnitude of the elastic force generated by the spring F k The calculation formula is (2) in, The spring constant (also called the stiffness coefficient or elasticity coefficient) is measured in Newtons per meter (N / m). This represents the length by which a spring is stretched or shortened relative to its free length within its elastic limit; the unit is meters (m). - The negative sign indicates that the elastic force generated by the spring is opposite to the direction of its elongation (or compression).

[0026] Combining (1) and (2), it can be seen that if a suitable mechanism is constructed to connect a rotating object to a spring, the spring force and the centripetal force of the rotation can be combined to create a space that compresses or expands with the rotational speed: when the rotational speed of the object increases, the centrifugal force increases, causing it to move outward from the circumference while stretching or compressing the spring; when the rotational speed decreases, the centrifugal force decreases, and the object returns to its original position under the action of the spring force. Furthermore, if cooling oil is added to this compressible space, when the rotational speed increases, the space is compressed due to the centrifugal force, thus injecting the cooling oil into the cooling channel; when the rotational speed decreases, the space expands due to the spring force, thus allowing the cooling oil to return from the oil channel to the cooling chamber.

[0027] Motor Example: like Figure 1 The rotor cooling device shown is a rotor cooling device. Figure 2 From the same perspective, in a plan view, the bottom of the cylinder body 107 is connected to an elastic element 101 via a connecting plate 105. The elastic element 101 is connected to the piston 103, which fits tightly against the inner cavity of the cylinder body 107. The cylinder body 107 and the connecting plate 105 are separately formed and sealed together. There is a mounting hole 108 on each side of the cylinder body 107 for installing positioning screws. The piston 103 divides the internal cavity of the cylinder body 107 into two sealed sections: a liquid-free chamber 102 and a cooling chamber 104 containing a connecting hole 106. The liquid-free chamber 102 is open to the atmosphere, ensuring piston movement. The oil injection hole 109, used to inject cooling medium into the motor rotor at the factory, can be blocked by the piston 103 after oil injection. The length of the piston 103 ensures that the oil injection hole 109 is sealed throughout its entire stroke. The oil injection hole 109 can also be sealed using a dedicated sealing plug.

[0028] When the rotor stops operating, the elastic element 101 is in a free extension and retraction state, and the piston 103 is located at a distance from the bottom of the cooling chamber 104. r 0 When the rotor rotates at high speed, the piston 103 will be subjected to centrifugal force. The magnitude of the centrifugal force can be calculated from formula (1). ,in Therefore, the elastic element 101 is compressed, and the piston 103 is moved from the bottom of the cooling chamber 104. r0 Move to a distance of 104 from the bottom of the cooling chamber r When the force reaches equilibrium, the elastic force of the elastic element 101 is equal to the centrifugal force required by the piston 103. Combining formulas (1) and (2), the displacement of the elastic element 101 can be obtained. x (numerically equal to) r 1 - r ), Elastic modulus of elastic element 101 k Rotation speed n The correspondence is (3) According to formula (3), when the rotational speed n When the piston 103 is raised, the centrifugal force required for its movement increases, and the compression of the elastic element 101 increases. r 1 / r As the speed increases, the air pressure in cooling chamber 104 decreases, and more cooling oil is "drawn" into cooling chamber 104; when the speed increases... n When the piston 103 is lowered, the centrifugal force required for its movement decreases, and the compression of the elastic element 101 decreases. r 1 / r As the rotor speed decreases, the air pressure in the cooling chamber 104 increases, forcing more cooling oil out of the chamber. This allows the cooling oil to flow within the rotor as the rotational speed changes. Simultaneously, the relationship between the position of the elastic element 101 and the rotational speed can be determined. By coordinating this with the position of the movable connecting hole 106, the connecting hole 106 can be closed by the piston 103 below a certain speed; only when the speed reaches a certain level will the piston 103 move to open the connecting hole 106. This ensures that the rotor cooling function is not activated at low speeds, but only activates after a certain speed is reached.

[0029] The elastic element 101 can be a spring, or in other embodiments, it can be a rubber element or a gas spring.

[0030] In another embodiment, the piston 103 has a protrusion extending into the cooling chamber 104 on its end face facing the cooling chamber 104. This protrusion allows as much coolant as possible to be discharged into the rotor cooling channel before the piston 103 blocks the connecting hole 106, thereby enhancing the cooling effect. Specifically, the protrusion is an inclined surface extending into the cooling chamber 104, with the inclined direction facing the connecting hole. This helps the piston to squeeze the coolant out of the connecting hole during movement, reducing the resistance to the coolant flowing out of the connecting hole 106.

[0031] The aforementioned rotor cooling device is installed at one axial end of the motor rotor. This device is positioned away from the rotor's rotation axis to ensure sufficient centrifugal force on the piston during rotation. Simultaneously, the axial direction of the cylinder 107 of the rotor cooling device coincides with the radial direction of the rotor end face, ensuring the piston can move along the cylinder's axis after being subjected to centripetal force. A variable-volume oil reservoir is installed at the other axial end. Specifically, this could be a variable-volume rubber oil reservoir; alternatively, it could be a piston cylinder using a lightweight piston. This piston is unaffected by the rotor's centrifugal force and does not have any elastic components; its purpose is simply to change volume as the cooling chamber of the opposing rotor cooling device changes. A cooling channel is formed axially inside the motor rotor. One end of the cooling channel connects to the connecting hole 106 of the rotor cooling device, and the other end connects to the oil reservoir. The cooling chamber, cooling channels, and oil storage structure of the rotor cooling device are filled with cooling oil as the cooling medium. When the motor rotates and the rotor speed changes continuously, the piston moves along the axis of its cylinder 107 under the action of centrifugal force, compressing and discharging the cooling oil in the cooling chamber of the rotor cooling device into the opposite oil storage structure, or expanding and drawing cooling oil into the opposite oil storage structure. During the process of drawing and discharging cooling oil from the cooling chamber of the rotor cooling device, the cooling oil repeatedly flows through the rotor cooling channels to dissipate heat from the rotor.

[0032] In addition, a rotor cooling device can be installed at each of the two ends of the motor rotor along the axial direction. The cylinders of the device are named the first cylinder and the second cylinder, respectively. The first cylinder, the second cylinder, and the cooling channel connecting the two constitute a heat dissipation unit. In order to ensure that the motor rotor is homogeneous in the circumferential direction and rotates smoothly, multiple sets of heat dissipation units can be evenly spaced on the motor rotor.

[0033] In the preferred embodiment, the number of heat dissipation units should be even and evenly distributed on the end face of the rotor. Simultaneously, the first and second cylinders should be spaced apart to ensure uniform axial mass of the motor rotor. During motor operation, the cooling oil in adjacent heat dissipation units flows in opposite directions to prevent oil concentration at one end of the rotor, which could cause imbalance. Figure 3 The diagram shows one end face of the motor rotor, which is a schematic diagram of the rotor end face with four heat dissipation units. The first cylinder 1071 and the second cylinder 1072 are both mounted on the rotor core 202 and positioned away from the rotational axis of the motor main shaft 201. The cooling chamber of the first cylinder 1071 is close to the motor main shaft at the center of the rotor, while the cooling chamber of the second cylinder 1072 is away from the motor main shaft at the center of the rotor. The elastic element in the first cylinder 1071 is a compression spring 1011, and the elastic element in the second cylinder 1072 is a tension spring 1012. These are respectively located in the liquid-free chambers of their respective cylinders, allowing one cylinder to draw in cooling oil and the other to discharge cooling oil simultaneously during operation.

[0034] In another embodiment, as the motor rotor speed decreases, the centrifugal force on the piston decreases, and the piston in the rotor cooling device moves towards the motor shaft under the action of the spring force. When the speed is lower than the set speed, the piston blocks the connecting hole, and the cooling oil stops flowing. At the same time, since the cooling oil is difficult to compress, the piston stops moving and remains at the blocked position. As can be seen from formula (3), there is a unique correspondence between the rotational speed and the displacement change of the piston. Therefore, there must be a corresponding set speed for the position where the piston just starts to block the connecting hole. This achieves the goal of stopping the flow of cooling oil when the motor speed is lower than the set value, that is, when the motor rotor does not need cooling, thus reducing the influence of the rotor's center of mass changing with the flow of cooling oil on the moment of inertia at low speeds.

[0035] The specific work process is as follows: Figure 4 , Figure 5 As shown, when the rotor speed increases, the centrifugal force generated by the piston 103 in the first cylinder 1071 on the left side of the figure is greater than the thrust provided by the compression spring 1011, and the centrifugal force of the piston in the second cylinder 1072 on the right side is greater than the tension of the corresponding tension spring 1012. Both the left and right pistons move towards... Figure 4 The rotor moves upwards (away from the rotor's rotation axis, i.e., the direction of the motor's main shaft). The left cooling chamber 104 enlarges to draw in cooling oil, while the right cooling chamber shrinks to discharge cooling oil. The cooling oil flows from right to left in the cooling channel 203. When the rotor speed decreases, the centrifugal force generated by the piston 103 in the first cylinder 1071 on the left is less than the thrust provided by the compression spring 1011, and the centrifugal force of the piston in the second cylinder 1072 on the right is less than the tension of the corresponding tension spring 1012. Both the left and right pistons move upwards. Figure 2 The piston moves downward (towards the rotor's rotation axis, i.e., the direction of the motor's main shaft). The left cooling chamber 104 shrinks to discharge cooling oil, while the right cooling chamber expands to draw in cooling oil. The cooling oil flows from left to right in the cooling channel 203. When the rotor speed is less than the set speed, the piston 103 stops at the blocking position of the corresponding connecting hole 106, and both ends of the cooling channel 203 are closed, thus the rotor cooling function is not activated.

[0036] For motors that use the above-mentioned rotor cooling structure, such as Figure 6 As shown, in addition to using the rotor cooling method described above, it can also be combined with the stator cooling method, such as adding a flow channel through the motor stator 204 to cool the motor stator 204 at the same time; the motor spindle 201 can also open a hollow oil channel to connect with the rotor cooling flow channel 203, thereby realizing the integrated design of motor oil cooling.

[0037] Vehicle Example: Furthermore, the present invention also provides a vehicle using an electric motor employing the aforementioned rotor cooling structure. The cooling principle and specific implementation method are the same, and therefore will not be repeated here.

Claims

1. An electric motor, characterized in that, include: The motor rotor includes a heat dissipation unit, which includes a first cylinder and a second cylinder, respectively located at two ends of the motor rotor's axial direction and offset from the rotor's rotation axis, and facing each other. The axial directions of the first and second cylinders coincide with the radial directions of the rotor end faces. Pistons are slidably and sealingly mounted in both the first and second cylinders along the radial direction of the motor rotor. The pistons divide the inner cavities of the corresponding cylinders into a cooling cavity and a liquid-free cavity for storing coolant. The cooling cavity of the first cylinder is close to the rotor's rotation axis, and the liquid-free cavity of the second cylinder is also close to the rotor's rotation axis. The pistons are connected to a first elastic element, which applies an elastic force to the corresponding pistons, forcing them to move toward the rotation axis of the motor rotor. The heat dissipation unit also includes a cooling channel extending along the axial direction of the motor rotor inside the motor rotor, the cooling channel connecting the cooling chambers of the first cylinder and the second cylinder. During the rotation of the motor rotor, when the rotor speed increases, the piston moves away from the central axis of the motor rotor under the action of centrifugal force. The first cylinder cooling chamber enlarges to draw in coolant, while the second cylinder cooling chamber shrinks to discharge coolant. When the rotor speed decreases, the piston moves towards the central axis of the motor rotor under the action of elastic force. The first cylinder cooling chamber shrinks to discharge coolant, while the second cylinder cooling chamber enlarges to draw in coolant. This drives the coolant to flow back and forth in the cooling channel, thereby dissipating heat from the motor rotor. The heat dissipation unit has four or more evenly spaced groups on the motor rotor, and the first cylinder and the second cylinder are spaced apart at any end of the motor rotor axially to ensure that the motor rotor is homogeneous in the circumferential direction and rotates smoothly.

2. The motor according to claim 1, characterized in that, The heat dissipation unit has four sets, with the first cylinder and the second cylinder spaced at four equally spaced positions on any end of the motor rotor axis.

3. The motor according to claim 1, characterized in that, The cooling channel is connected to the first cylinder and the second cylinder through a connecting hole; the first piston or the second piston has a blocking position that blocks the corresponding connecting hole during its stroke; when the motor rotor speed is lower than the set value, the first piston or the second piston stays at the blocking position.

4. The motor according to claim 3, characterized in that, The first piston and / or the second piston have protrusions extending into the cooling chamber on their surfaces facing the cooling chamber, avoiding the connecting hole.

5. The motor according to claim 4, characterized in that, The protrusion includes an inclined surface with a bevel facing the connecting hole.

6. The motor according to claim 5, characterized in that, The cooling channel is inclined in the motor rotor, and the distance from the end of the cooling channel that connects to the cooling chamber of the first cylinder to the rotation center axis of the motor rotor is close to the distance from the end of the cooling channel that connects to the cooling chamber of the second cylinder to the rotation center axis of the motor rotor.

7. The motor according to claim 6, characterized in that, The first elastic element is a compression spring, which is disposed in the liquid-free chamber of the first cylinder; the second elastic element is a tension spring, which is disposed in the liquid-free chamber of the second cylinder.

8. The motor according to claim 1, characterized in that, The oil injection hole for injecting the cooling medium is blocked by the piston after the oil injection is completed.

9. The motor according to claim 1, characterized in that, The motor spindle has a hollow oil passage that is connected to the cooling channel.

10. A vehicle, characterized in that, An electric motor is used, the electric motor comprising: The motor rotor includes a heat dissipation unit, which includes a first cylinder and a second cylinder, respectively located at two ends of the motor rotor's axial direction and offset from the rotor's rotation axis, and facing each other. The axial directions of the first and second cylinders coincide with the radial directions of the rotor end faces. Pistons are slidably and sealingly mounted in both the first and second cylinders along the radial direction of the motor rotor. The pistons divide the inner cavities of the corresponding cylinders into a cooling cavity and a liquid-free cavity for storing coolant. The cooling cavity of the first cylinder is close to the rotor's rotation axis, and the liquid-free cavity of the second cylinder is also close to the rotor's rotation axis. The pistons are connected to a first elastic element, which applies an elastic force to the corresponding pistons, forcing them to move toward the rotation axis of the motor rotor. The heat dissipation unit also includes a cooling channel extending along the axial direction of the motor rotor inside the motor rotor, the cooling channel connecting the cooling chambers of the first cylinder and the second cylinder. During the rotation of the motor rotor, when the rotor speed increases, the piston moves away from the central axis of the motor rotor under the action of centrifugal force. The first cylinder cooling chamber enlarges to draw in coolant, while the second cylinder cooling chamber shrinks to discharge coolant. When the rotor speed decreases, the piston moves towards the central axis of the motor rotor under the action of elastic force. The first cylinder cooling chamber shrinks to discharge coolant, while the second cylinder cooling chamber enlarges to draw in coolant. This drives the coolant to flow back and forth in the cooling channel, thereby dissipating heat from the motor rotor. The heat dissipation unit has four or more evenly spaced groups on the motor rotor, and the first cylinder and the second cylinder are spaced apart to ensure that the motor rotor is homogeneous in the circumferential direction and rotates smoothly.

11. The vehicle according to claim 10, characterized in that, When the speed is lower than the set speed, the piston will block the connecting hole connected to the cooling channel, and the cooling oil will no longer flow.

12. The vehicle according to claim 10, characterized in that, The cooling channel is connected to the first cylinder and the second cylinder through a connecting hole; the first piston or the second piston has a blocking position that blocks the corresponding connecting hole during its stroke; when the motor rotor speed is lower than the set value, the first piston or the second piston stays at the blocking position.

13. The vehicle according to claim 12, characterized in that, The first piston and / or the second piston have protrusions extending into the cooling chamber on their surfaces facing the cooling chamber, avoiding the connecting hole.

14. The vehicle according to claim 13, characterized in that, The protrusion includes an inclined surface with a bevel facing the connecting hole.

15. The vehicle according to claim 14, characterized in that, The cooling channel is inclined in the motor rotor, and the distance from the end of the cooling channel that connects to the cooling chamber of the first cylinder to the rotation center axis of the motor rotor is close to the distance from the end of the cooling channel that connects to the cooling chamber of the second cylinder to the rotation center axis of the motor rotor.

16. The vehicle according to claim 15, characterized in that, The first elastic element is a compression spring, which is disposed in the liquid-free chamber of the first cylinder; the second elastic element is a tension spring, which is disposed in the liquid-free chamber of the second cylinder.

17. The vehicle according to claim 10, characterized in that, The oil injection hole for injecting the cooling medium is blocked by the piston after the oil injection is completed.

18. The vehicle according to claim 10, characterized in that, The motor spindle has a hollow oil passage that is connected to the cooling channel.

Images