A cooling system for a hub motor

Abstract

The present invention discloses a cooling system for a hub motor, comprising a radiator, a PDU / DCDC / OBC three-in-one device, a hub motor, and a hub motor controller; the hub motor is provided with a cooling water jacket for cooling the hub motor stator coil, and a self-priming pump connected to the cooling water jacket; the cold source outlet of the radiator is connected in sequence to the interior of the PDU / DCDC / OBC three-in-one device and the hub motor controller; the coolant outlet of the hub motor controller is connected to the water inlet of the self-priming pump inside the hub motor, and the interior of the self-priming pump is connected to the cooling water jacket; the water outlet of the self-priming pump is connected to the cold source inlet of the radiator through a cooling water pipe. The beneficial effects of the present invention are as follows: the cooling system of the present invention does not require a dedicated water pump, the power consumption of the entire vehicle is reduced, and the cruising range is improved to a certain extent; the bidirectional plunger pump is assembled in the cooling water jacket, and its axial action with the rotating cam structure of the hub bearing produces a pumping effect, thereby realizing the circulation of the coolant.

Description

Technical Field

[0001] The present invention relates to the field of cooling technology, and in particular to a cooling system for a hub motor. Background Art

[0002] In-wheel motor drive is one of the important development directions of new energy vehicles. Its principle is to install the motor inside the rim of the car and drive the wheel directly by the motor, eliminating the traditional transmission device. Taking a certain in-wheel motor as an example, the structure is as follows Figure 1 As shown ( Figure 1 1-wheel, 2-hub motor outer rotor, 3-brake disc, 4-cooling water pipe interface, 5-low-voltage signal harness interface, 6-high-voltage harness interface, 7-brake caliper, 8-hub motor stator).

[0003] Most new energy passenger vehicles use in-wheel motors with external rotors. Because they utilize direct in-wheel drive, they eliminate transmission components, resulting in a simple transmission structure and flexible drive methods. To improve the motor's power and torque density, current motors mostly use three-phase AC permanent magnet synchronous motors. However, due to the limitations of the current NdFeB permanent magnet technology, they typically begin to demagnetize at around 180°C. Due to the complex driving conditions of vehicles, especially when climbing long slopes with heavy loads, temperatures rise rapidly. Although maximum temperature rise is considered and a safety factor is reserved during motor design, the uncertainty of actual use, the performance degradation of components and materials, and the influence of different road conditions and extreme environments often lead to discrepancies between design and actual performance. This is especially true given the current immaturity of automotive in-wheel motor drives, which necessitates a more efficient and reliable cooling system.

[0004] Outer rotor permanent magnet synchronous motors are developing towards higher power density. Reducing size not only increases power density but also reduces costs. However, to meet the required torque, the magnetic flux density is generally increased. However, the magnetic flux density of the silicon steel laminations is difficult to increase after reaching 1.95T. Moreover, most drive motors are saturated during peak operation, making further increases in magnetic flux density impossible with current technology. Therefore, to increase power density, the most ideal solution under current circumstances is to improve the motor's heat dissipation.

[0005] The cooling technology for permanent magnet synchronous motors (PMSMs), used in most in-wheel hub motors, has reached a mature stage. Air cooling, liquid cooling, or hybrid cooling are selected based on motor performance. Currently, all research focuses on internal motor heat dissipation, particularly on optimizing water channels and selecting cooling methods. However, due to insufficient data collection on in-wheel hub motor operating conditions, most research has been transplanted from integrated motors, resulting in limited improvements in reliability and limited results.

[0006] Currently, the commonly used Figure 2 The in-wheel motor system cooling solution shown in the figure: a water pump first pumps the coolant in the radiator into the controller (some need to be pumped into the PDU or "three-in-one" first). The coolant flowing out of the motor controller is divided into two branches, entering the left and right in-wheel motors respectively (some also have a main path flowing through the left and right motors respectively). Finally, the coolant flowing out of the motors is combined into a main path to flow into the radiator for heat dissipation. Among them, the coolant entering the motor is generally required to be below 65°C, and the maximum temperature inside the motor is below 140°C. Figure 3 This is the wheel hub motor liquid cooling system used on a certain vehicle model. Figure 3 (Image: 9 - Radiator, 10 - Cooling Water Pump, 11 - PDU / DCDC / OBC 3-in-1, 12 - Right Wheel Hub Motor, 13 - Left Wheel Hub Motor, 14 - Cooling Water Pipe, 15 - Wheel Hub Motor Controller). The coolant circulation process is: 9 → 10 → 11 → 15 → 12 / 13 → 9. Water pump 10 pumps the coolant from radiator 9 into 3-in-1 11. After exiting 3-in-1 11, the coolant flows through long cooling water pipe 14 into motor controller 15. The coolant from motor controller 15 then splits into left and right branches, entering left and right wheel hub motors 12 and 13, respectively. Finally, the coolant flowing from wheel hub motors 12 and 13 merges into a main flow, flowing into radiator 9 for heat dissipation.

[0007] However, when applying the existing technical solutions to cool the hub motor, the following problems exist:

[0008] (1) The system is driven by two or four wheel hub motors instead of one centralized motor. The increase in the number of motors and the demand for large torque from the wheel hub motors will lead to a significant increase in the heat dissipation of the system. The size of the original radiator 9 may be difficult to meet the heat dissipation requirements, resulting in problems of insufficient heat dissipation and untimely heat dissipation.

[0009] (2) Once the external water pump has a problem, the cooling system will not work and the motor temperature will rise rapidly. If other strategies fail, the motor may burn out and have poor reliability.

[0010] (3) When the hub motor body and the controller are integrated into one, the current cooling system will be very complicated due to spatial layout reasons, and the increased flow resistance will result in unsatisfactory cooling effect. Summary of the Invention

[0011] The object of the present invention is to provide a cooling system for a hub motor with good heat dissipation effect, low energy consumption and high reliability, in order to address the deficiencies of the prior art.

[0012] The technical solution adopted by the present invention is: a cooling system for a hub motor, the cooling system including a radiator, a PDU / DCDC / OBC three-in-one device, a hub motor and a hub motor controller; the hub motor is provided with a cooling water jacket for cooling the stator coil of the hub motor, and a bidirectional plunger pump connected to the cooling water jacket; the cold source outlet of the radiator is connected to the interior of the PDU / DCDC / OBC three-in-one device and the hub motor controller in sequence, the coolant outlet of the hub motor controller is connected to the water inlet of the self-priming pump inside the hub motor, and the interior of the self-priming pump is connected to the cooling water jacket; the water outlet of the self-priming pump is connected to the cold source inlet of the radiator through a cooling water pipe.

[0013] According to the above scheme, the hub motor includes a hub bearing, a stator frame, a stator wound with coils, a rotor press-fitted with magnetic steel, a self-priming pump and a cooling water jacket for cooling the stator coils; the inner ring of the hub bearing is fixedly connected to the stator frame on which the stator is mounted, and the outer ring of the hub bearing is an outer ring flange surface adapted to the rotor; the self-priming pump is a bidirectional plunger pump installed in the cooling water jacket, the push rod of the bidirectional plunger pump contacts the outer ring flange surface, and when the rotor drives the outer ring flange surface to rotate, the push rod of the bidirectional plunger pump moves axially; the water inlet of the bidirectional plunger pump is connected to the coolant outlet of the motor controller, and the water outlet of the plunger pump is connected to the coolant inlet of the motor controller; the stator and the cooling water jacket are coaxially assembled on the stator frame, and a flow channel is opened in the cooling water jacket, which is connected to the interior of the bidirectional plunger pump; when the push rod of the bidirectional plunger pump moves axially, the coolant in the bidirectional plunger pump and the cooling water jacket flows, and performs convection heat exchange with the stator heat source.

[0014] According to the above scheme, the outer ring flange surface of the hub bearing is additionally provided with a rotating cam structure protruding along the axial direction; the push rod contacts the rotatable cam structure, and when the rotor drives the outer ring flange surface to rotate, the rotating cam structure pushes the push rod of the bidirectional plunger pump to move axially.

[0015] According to the above scheme, the bidirectional plunger pump includes a pump body connected to the push rod, and a first pump chamber and a second pump chamber coaxially arranged in the pump body; a water inlet and a water outlet are respectively provided on both sides of the first pump chamber, and four one-way valves connecting the first pump chamber and the second pump chamber are respectively provided between the two; the plunger is installed in the second pump chamber, and the plunger can move back and forth axially under the drive of the push rod; the plunger divides the second pump chamber into an upper cavity and a lower cavity, and the upper cavity and the lower cavity are respectively connected to the first pump chamber through two one-way valves; the plunger can move axially under the drive of the push rod.

[0016] According to the above scheme, the four one-way valves are the first one-way valve, the second one-way valve, the third one-way valve and the fourth one-way valve respectively; when the push rod is in the descending stage, the first one-way valve and the fourth one-way valve are opened, the second one-way valve and the third one-way valve are closed, and the coolant enters the upper cavity through the water inlet through the first one-way valve, and at the same time flows out from the water outlet in the lower cavity through the fourth one-way valve; when the push rod is in the ascending stage, the second one-way valve and the third one-way valve are opened, the first one-way valve and the fourth one-way valve are closed, and the coolant enters the lower cavity through the water inlet through the second one-way valve, and at the same time flows out from the water outlet in the upper cavity through the third one-way valve.

[0017] According to the above solution, there are three bidirectional plunger pumps, which are installed in the cooling water jacket at even intervals in the circumferential direction.

[0018] According to the above scheme, a U-shaped or spiral flow channel is opened in the cooling water jacket, and the flow channel is connected to a water inlet pipe and a water outlet pipe respectively, wherein the water inlet pipe is connected to the water inlet of the bidirectional plunger pump through a first flow hole, and the water outlet pipe is connected to the water outlet of the bidirectional plunger pump through a second flow hole.

[0019] According to the above solution, a blocking piece is provided between the first flow hole and the second flow hole.

[0020] The beneficial effects of the present invention are:

[0021] (1) Compared with the traditional "-radiator-water pump-controller and motor" cooling system, the cooling system of the present invention does not require a dedicated water pump, the power consumption of the whole vehicle is reduced, and the cruising range is improved to a certain extent;

[0022] (2) In the present invention, the bidirectional plunger pump is installed in the cooling water jacket, and the axial action of the rotating cam structure with the wheel hub bearing produces a pumping effect, thereby realizing the circulation of the coolant, reducing the heat dissipation power consumption of the motor, and at the same time reducing the flow resistance loss caused by the heat dissipation path, forming forced convection heat dissipation inside the motor, and avoiding insufficient heat dissipation and untimely heat dissipation; and regardless of whether the wheel hub motor rotates forward or reverse, the coolant will be cooled from the fixed flow channel; as long as the rotor is rotating, the coolant will be pumped and circulated, and the faster the rotation speed, the faster the circulation, which improves the timeliness of heat dissipation. At the same time, due to the linkage between the cooling system and the motor, its reliability is also improved;

[0023] (3) The present invention can be implemented by installing a plurality of bidirectional plunger pumps arranged at intervals on the cooling water jacket, and the number of rotary cam structures on the flange surface of the bearing outer ring can be changed according to the flow requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of an existing hub motor.

[0025] Figure 2 This is a flow chart of the existing hub motor liquid cooling system.

[0026] Figure 3 The figure is a schematic diagram of the overall structure of the hub motor liquid cooling system in the prior art.

[0027] Figure 4 This is a flowchart of a specific embodiment of the present invention.

[0028] Figure 5 Schematic diagram of the structure of this embodiment.

[0029] Figure 6 Schematic diagram of the structure of the hub motor in this embodiment.

[0030] Figure 7 Schematic diagram of the overall bidirectional plunger pump in this embodiment.

[0031] Figure 8 2 is a cross-sectional view of the bidirectional plunger pump in this embodiment.

[0032] Figure 9 Schematic diagram of the structure of the hub bearing in this embodiment.

[0033] Figure 10 Schematic diagram of the structure of the cooling water jacket in this embodiment. DETAILED DESCRIPTION

[0034] In order to better understand the present invention, the present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0035] In the present invention, a PDU (Power Distribution Unit) is a high-voltage distribution box; a DC-DC (Direct Current) is a device that converts a DC power supply of a certain voltage level into a DC power supply of another voltage level; an OBC (On-Board Controller) is an on-board charger; and the PDU / DCDC / OBC three-in-one device 10 integrates the functions of the three devices into one device. This is an existing device in the industry and will not be described in detail here.

[0036] like Figure 4 and Figure 5 A cooling system for a hub motor is shown. Figure 4The reference numerals in the figures are: 9 - radiator, 10 - PDU / DCDC / OBC three-in-one device, 11 - right hub motor, 12 - left hub motor, 13 - cooling water pipe, 14 - hub motor controller. The cooling system includes a radiator 9, a PDU / DCDC / OBC three-in-one device 10, a hub motor, and a hub motor controller 14. The hub motor is provided with a cooling water jacket 16 for cooling the coils of the hub motor stator 18, and a self-priming pump connected to the cooling water jacket 16. The cold source outlet of the radiator 9 is connected to the interior of the PDU / DCDC / OBC three-in-one device 10 and the hub motor controller 14 in sequence. The coolant outlet of the hub motor controller 14 is connected to the water inlet of the self-priming pump inside the hub motor. The coolant channel in the self-priming pump is connected to the cooling water jacket 16 for cooling the coils of the hub motor stator 18. The water outlet of the self-priming pump is connected to the cold source inlet of the radiator 9 through the cooling water pipe 13.

[0037] The wheel hub motor includes a left wheel hub motor 12 and a right wheel hub motor 11. In this embodiment, the coolant outlet of the wheel hub motor controller 14 is connected to the water inlet of the self-priming pump inside the left wheel hub motor 12, and enters the cooling water jacket 16 through the self-priming pump to cool the stator 18 coil of the left wheel hub motor 12. The coolant flows back into the self-priming pump, flows out through the water blowing port of the self-priming pump, and enters the self-priming pump inside the right wheel hub motor 11 through the pipeline. After flowing into the cooling water jacket 16 inside the right wheel hub motor 11, it flows back to the water outlet of the self-priming pump of the right wheel hub motor 11 and flows out, and is connected to the cold source inlet of the radiator 9 through the cooling water pipe 13. The driving force for the coolant to reflux in the cooling system comes from the self-priming pump inside the hub motor. The coolant circulation process is: radiator 9 → PDU / DCDC / OBC three-in-one device 10 → cooling water pipe 13 → hub motor controller 14 → hub motor (it can first enter the hub motor and then the right hub motor 11, or it can first enter the right hub motor 11 and then the left hub motor 12) → cooling water pipe 13 → radiator 9.

[0038] The present invention connects the self-priming pump of the hub motor in series to the entire cooling circuit, eliminating the dedicated water pump in the prior art. The coolant flows out of the radiator 9 and enters the hub motor controller 14 and the left / right hub motor 11 in sequence. The self-priming pump inside the hub motor allows the coolant to exchange heat within the entire system, thereby achieving the heat dissipation function of the hub motor.

[0039] In the present invention, the structure of the hub motor is as follows Figure 6 As shown, Figure 6The reference numerals in the figures are: 15 - bidirectional piston pump, 16 - cooling water jacket, 17 - stator frame, 18 - stator, 19 - rotor, 20 - wheel hub bearing. The wheel hub motor comprises a wheel hub bearing 20, a stator frame 17, a stator 18 wound with coils, a rotor 19 with magnetic steel pressed in, a self-priming pump and a cooling water jacket 16 for cooling the stator 18 coils; the inner ring flange surface 34 of the wheel hub bearing 20 is fixedly connected (can be bolted) to the stator frame 17 on which the stator 18 is mounted, the outer ring flange surface 35 of the wheel hub bearing 20 is adapted to the rotor 19, and the outer ring flange surface 35 is additionally provided with a rotary cam structure 36 protruding along the axial direction; the self-priming pump is a bidirectional piston pump 15 mounted in the cooling water jacket 16, the push rod 22 of the bidirectional piston pump 15 is in contact with the rotatable cam structure 36, and the rotor 19 drives the outer ring flange When the surface 35 rotates, the push rod 22 of the bidirectional plunger pump 15 moves axially; the water inlet of the bidirectional plunger pump 15 is connected to the coolant outlet of the motor controller, and the water outlet of the plunger pump is connected to the coolant inlet of the motor controller; the stator 18 and the cooling water jacket 16 are coaxially assembled on the stator frame 17, and a flow channel is opened in the cooling water jacket 16, and the flow channel is connected to the interior of the bidirectional plunger pump 15; when the push rod 22 of the bidirectional plunger pump 15 moves axially, the coolant in the bidirectional plunger pump 15 and the cooling water jacket 16 flows and performs convection heat exchange with the heat source of the stator 18, thereby realizing the internal circulation of the coolant to dissipate the heat generated by the stator 18 coil.

[0040] In the present invention, the self-priming cooling principle of the entire hub motor is achieved by specially designing the cooling water jacket 16 and the bidirectional plunger pump 15. The cooling water jacket 16 has a built-in bidirectional plunger pump 15, and the outer ring flange surface 35 of the hub bearing 20 is additionally provided with a rotary cam structure 36. The rotation of the rotor 19 drives the outer ring flange surface 35 to rotate, and the rotary cam structure 36 pushes the push rod 22 of the bidirectional plunger pump 15 to move axially, so that the coolant in the cooling water jacket 16 and the stator 18 heat source are forced to exchange heat by convection, thereby realizing the internal circulation of the coolant to dissipate the heat generated by the stator coil. The coolant circulation speed changes with the speed. In order to reduce the loss caused by the axial action, it can be optimized from the following three aspects: (1) improving the lubrication conditions of the two to reduce the friction coefficient; (2) by optimizing the cam profile stroke, the axial impact effect can be reduced; (3) by optimizing the stiffness coefficient of the internal spring of the plunger pump, the axial load can be reduced and the rebound response can be increased.

[0041] The structure of the bidirectional plunger pump 15 is as follows: Figure 7 and Figure 8 shown. Figure 7 and Figure 8The reference numerals in the figures are: 21-pump body, 22-rod, 23-plunger, 24-first pump chamber, 25-upper chamber, 26-lower chamber, 27-first one-way valve, 28-second one-way valve, 29-third one-way valve, 30-fourth one-way valve, 31-spring, 32-water inlet, 33-water outlet. Preferably, the bidirectional plunger pump 15 includes a pump body 21 connected to a push rod 22, and a first pump chamber 24 and a second pump chamber coaxially arranged within the pump body 21. The first pump chamber 24 is provided with a water inlet and a water outlet on either side, and four one-way valves are provided between the first pump chamber 24 and the second pump chamber, connecting the two. The plunger 23 is installed in the second pump chamber and can reciprocate axially under the drive of the push rod 22. The plunger 23 divides the second pump chamber into an upper chamber 25 and a lower chamber 26, each of which is connected to the first pump chamber 24 via two one-way valves. The plunger 23 can move axially under the drive of the push rod 22. A spring 31 is provided at the bottom of the second pump chamber, and the bottom of the plunger 23 can contact the spring 31.

[0042] In this embodiment, the four one-way valves are the first one-way valve 27, the second one-way valve 28, the third one-way valve 29 and the fourth one-way valve 30. The push rod 22 is linked to the rotary cam structure 36 of the hub bearing 20. Driven by the rotor 19, the push rod 22 drives the plunger 23 to move back and forth in an axial direction: (1) When the push rod 22 is in the descending stage (the push rod 22 drives the plunger 23 to move downward), the first one-way valve 27 and the fourth one-way valve 30 are opened, the second one-way valve 28 and the third one-way valve 29 are closed, and the coolant enters the expansion chamber (i.e., the upper chamber) through the water inlet 32 ​​and the first one-way valve 27. 25), and at the same time, it flows out of the compression chamber (i.e., the lower chamber 26) through the fourth one-way valve 30 from the water outlet 33; (2) when the push rod 22 is in the ascending stage, the second one-way valve 28 and the third one-way valve 29 are opened, the first one-way valve 27 and the fourth one-way valve 30 are closed, and the coolant enters the expansion chamber (lower chamber 26) through the second one-way valve 28 through the water inlet 32, and at the same time, it flows out of the compression chamber (upper chamber 25) through the third one-way valve 29 from the water outlet 33. The push rod 22 reciprocates as the rotor 19 rotates, and the coolant continuously flows in through the water inlet 32 ​​and flows out from the water outlet 33. In the present invention, three bidirectional plunger pumps 15 with a 120° interval are installed circumferentially on the cooling water jacket 16, and the number of the shaft rotating cam structures 36 can be changed according to the flow requirements to achieve this.

[0043] The structure of the hub bearing 20 is as follows Figure 9 As shown, Figure 9The accompanying drawings are labeled: 34 - inner ring flange surface, 35 - outer ring flange surface, 36 - rotating cam structure. The inner ring flange surface 34 of the hub bearing 20 is connected to the stator 18 and stator frame 17, respectively; the outer ring of the hub bearing 20 is connected to the rotor 19; and the outer ring flange surface 35 of the hub bearing 20 is designed with a rotating cam structure 36, the number of which is determined based on the required cooling flow rate. Other configurations of the hub bearing 20 are conventional and will not be described here. In the present invention, the inner ring flange surface 34 of the hub bearing 20 is connected to both the stator 18 and the stator frame 17 and remains stationary during electromagnetic operation. The outer ring flange surface 35 is connected to the rotor 19 and rotates continuously during electromagnetic operation.

[0044] The structure of the cooling water jacket 16 is as follows Figure 10 As shown, Figure 10 The figures are marked as: 37-water inlet pipe, 38-water outlet pipe, 39-flow channel. A U-shaped or spiral flow channel is provided in the cooling water jacket 16, and the flow channels are connected to the water inlet pipe and the water outlet pipe respectively, wherein the water inlet pipe is connected to the water inlet of the two-way plunger pump 15 through the first flow hole, and the water outlet pipe is connected to the water outlet of the two-way plunger pump 23 through the second flow hole; a baffle is provided between the first flow hole and the second flow hole. Due to the characteristics of the two-way plunger pump 15, regardless of whether the hub motor rotates forward or reverse, the coolant will only flow in through the water inlet pipe and flow out from the water outlet pipe. In the present invention, the cooling water jacket 16 is mainly used to cool the stator 18 coil assembled therewith. To install the two-way suction pump into the water jacket, two holes need to be made in the water jacket, which are respectively connected to the water inlet and outlet of the plunger pump. In order to ensure directional cooling, a baffle is provided between the two holes.

[0045] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cooling system for a hub motor, characterized in that: The cooling system includes a radiator, a PDU / DCDC / OBC three-in-one device, a hub motor and a hub motor controller; the hub motor is provided with a cooling water jacket for cooling the hub motor stator coil, and a self-priming pump connected to the cooling water jacket; the cold source outlet of the radiator is connected to the interior of the PDU / DCDC / OBC three-in-one device and the hub motor controller in sequence, the coolant outlet of the hub motor controller is connected to the water inlet of the self-priming pump inside the hub motor, and the interior of the self-priming pump is connected to the cooling water jacket; the water outlet of the self-priming pump is connected to the cold source inlet of the radiator through a cooling water pipe; The wheel hub motor includes a wheel hub bearing, a stator frame, a stator with coils wound around it, a rotor with magnetic steel pressed on it, a self-priming pump and a cooling water jacket for cooling the stator coils; the inner ring of the wheel hub bearing is fixedly connected to the stator frame on which the stator is installed, and the outer ring of the wheel hub bearing is an outer ring flange surface adapted to the rotor; the self-priming pump is a bidirectional plunger pump installed in the cooling water jacket, and the push rod of the bidirectional plunger pump contacts the outer ring flange surface. When the rotor drives the outer ring flange surface to rotate, the push rod of the bidirectional plunger pump moves axially; the water inlet of the bidirectional plunger pump is connected to the coolant outlet of the motor controller, and the water outlet of the plunger pump is connected to the coolant inlet of the motor controller; the stator and the cooling water jacket are coaxially assembled on the stator frame, and a flow channel is opened in the cooling water jacket, which is connected to the interior of the bidirectional plunger pump; when the push rod of the bidirectional plunger pump moves axially, the coolant in the bidirectional plunger pump and the cooling water jacket flows and performs convection heat exchange with the stator heat source; The outer ring flange surface of the hub bearing is additionally provided with a rotary cam structure protruding along the axial direction; the push rod contacts the rotary cam structure, and when the rotor drives the outer ring flange surface to rotate, the rotary cam structure pushes the push rod of the bidirectional plunger pump to move axially; The bidirectional plunger pump includes a pump body connected to a push rod, and a first pump chamber and a second pump chamber coaxially arranged in the pump body; a water inlet and a water outlet are respectively provided on both sides of the first pump chamber, and four one-way valves are respectively provided between the first pump chamber and the second pump chamber to connect the two chambers; the plunger is installed in the second pump chamber and moves back and forth in the axial direction under the drive of the push rod; The plunger divides the second pump chamber into an upper chamber and a lower chamber, and the upper chamber and the lower chamber are connected to the first pump chamber through two one-way valves respectively; the plunger moves axially under the drive of the ejector rod; Regardless of whether the hub motor rotates forward or reverse, the coolant will only flow in through the water inlet pipe and out from the water outlet pipe.

2. The cooling system according to claim 1, wherein: The four one-way valves are the first one-way valve, the second one-way valve, the third one-way valve and the fourth one-way valve; when the push rod is in the descending stage, the first one-way valve and the fourth one-way valve are opened, the second one-way valve and the third one-way valve are closed, and the coolant enters the upper cavity through the water inlet through the first one-way valve, and at the same time flows out from the water outlet in the lower cavity through the fourth one-way valve; when the push rod is in the ascending stage, the second one-way valve and the third one-way valve are opened, the first one-way valve and the fourth one-way valve are closed, and the coolant enters the lower cavity through the water inlet through the second one-way valve, and at the same time flows out from the water outlet in the upper cavity through the third one-way valve.

3. The cooling system according to claim 1, wherein: There are three bidirectional plunger pumps, which are evenly spaced circumferentially and installed on the cooling water jacket.

4. The cooling system according to claim 1, wherein: A U-shaped or spiral flow channel is provided in the cooling water jacket, and the flow channel is connected to a water inlet pipe and a water outlet pipe respectively, wherein the water inlet pipe is connected to the water inlet of the bidirectional plunger pump through a first flow hole, and the water outlet pipe is connected to the water outlet of the bidirectional plunger pump through a second flow hole.

5. The cooling system according to claim 4, wherein: A blocking piece is provided between the first flow hole and the second flow hole.

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