Drive motor for a vehicle

Abstract

A driving motor for a vehicle includes a stator, a rotor rotatably disposed inside the stator, a hollow shaft disposed inside the rotor, configured to be rotatable with the rotor and including a plurality of through holes, and a housing configured to accommodate the stator, the rotor, and the hollow shaft, and including a passage, wherein the passage is formed in an inner wall of the housing, and is configured to allow an upper side of the inner wall and an inside of the hollow shaft to communicate with each other and to allow oil to flow therein.

Description

Technical Field

[0001] This disclosure relates to drive motors for vehicles. Background Technology

[0002] The statements in this section provide only background information in connection with this disclosure and may not constitute prior art.

[0003] "Electric vehicles (EVs)" is a general term for vehicles equipped with rechargeable high-voltage, high-capacity batteries, including hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell electric vehicles (FCEVs).

[0004] Drive motors play a crucial role in powering environmentally friendly vehicles. Due to losses caused by heat, airflow, and noise, the efficiency of drive motors is approximately 90%. Heat loss accounts for about 25% of total losses, especially as the drive motor's temperature rises. If the drive motor is heated above its threshold temperature (the upper limit of its stable operating temperature), it will overheat, and the coils may burn out around the stator, or the permanent magnets in the rotor may demagnetize. Therefore, it is essential to incorporate appropriate cooling systems into drive motors to ensure they operate below the threshold temperature, and there is a continuous pursuit of improving drive motor cooling performance and efficiency to achieve smaller size and increased output.

[0005] Depending on the type of coolant, drive motors may be cooled by water, air, or oil. Similarly, drive motors can be cooled directly or indirectly based on the presence of contact. Recently, with the increasing importance of drive motor cooling capabilities and the growing demand for high-performance drive motors, direct oil cooling is increasingly being used for cooling drive motors.

[0006] Based on the injection type, direct oil cooling can include axial dispersion using a rotating drive motor and pressurized oil delivery via an electric oil pump (EOP). In recent years, the increasing demand for better cooling capabilities has led to a combined application of the former and the latter, where pressurized oil delivered by an EOP is used to cool the stator, and oil is distributed from the motor shaft to cool the rotor.

[0007] We are actively researching and developing drive motors to improve cooling performance, aiming to achieve a drive motor cooling structure that both reduces costs and improves cooling performance.

[0008] The foregoing is intended only to help understand the background of this disclosure and is not intended to imply that this disclosure falls within the scope of related technologies known to those skilled in the art. Summary of the Invention

[0009] This disclosure provides a drive motor with excellent cooling performance for use in vehicles.

[0010] This disclosure provides a drive motor for vehicles that has a simple structure and excellent cooling performance.

[0011] This disclosure provides a drive motor for vehicles that can provide improved driving performance.

[0012] This disclosure provides a drive motor for vehicles capable of suppressing the demagnetization of permanent magnets in the rotor.

[0013] One form of this disclosure provides a drive motor for a vehicle, the drive motor comprising: a stator; a rotor rotatably disposed within the stator; a hollow shaft disposed within the rotor and configured to rotate with the rotor and including a plurality of through holes; and a housing configured to receive the stator, rotor and hollow shaft, and including a channel formed in an inner wall of the housing and configured to allow an upper side of the inner wall and the interior of the hollow shaft to communicate with each other and allow oil to flow therein.

[0014] Another form of this disclosure provides a drive motor for a vehicle, the drive motor comprising: a stator wound with coils; a rotor rotatably disposed inside the stator and including a plurality of permanent magnets arranged therearound; a hollow shaft disposed inside the rotor, configured to rotate with the rotor, and including a plurality of through holes formed at predetermined distances along the circumference of the hollow shaft; and a housing configured to receive the stator, rotor and hollow shaft, and including channels formed in the inner wall of the housing, and configured to allow the upper side of the inner wall and the interior of the hollow shaft to communicate with each other and allow oil to flow therein.

[0015] Other application areas will become apparent from the description provided herein. It should be understood that the descriptions and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0016] To facilitate a good understanding of this disclosure, its various forms will now be described by way of example and with reference to the accompanying drawings, wherein:

[0017] Figure 1 It is a diagram showing the circulation process of oil used to cool the drive motor of a vehicle;

[0018] Figure 2 It is a cross-sectional view of a drive motor for a vehicle according to this disclosure;

[0019] Figure 3 yes Figure 2 An enlarged view of part A;

[0020] Figure 4 yes Figure 2 An enlarged view of Part B; and

[0021] Figure 5 The cross-sectional view of the drive motor for a vehicle according to this disclosure shows the oil flow path.

[0022] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way. Detailed Implementation

[0023] The following description is exemplary in nature only and is not intended to limit this disclosure, its application, or its uses. It should be understood that in all the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0024] It will be understood that although the terms “first,” “second,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the teachings of this disclosure, the first element discussed below may be referred to as the second element. Similarly, the second element may also be referred to as the first element.

[0025] What will be understood is that when an element is referred to as "coupled" or "connected" to another element, it can be directly coupled or connected to the other element, or there can be an intermediate element between them. Conversely, it should be understood that when an element is referred to as "directly coupled" or "directly connected" to another element, there is no intermediate element. Other expressions explaining relationships between elements, such as "between," "directly between," "adjacent," or "directly adjacent," should be analyzed in the same way.

[0026] Furthermore, the terminology used herein is for descriptive purposes only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that, when used in this specification, the terms “comprising,” “including,” “having,” etc., specify the presence of the stated components, steps, operations, and / or elements, but do not exclude the presence or addition of one or more other components, steps, operations, and / or elements thereof.

[0027] This disclosure will be described in detail below with reference to the accompanying drawings.

[0028] As described above, drive motor 1 can be cooled by oil supplied from EOP, and will refer to Figure 1 The process of cooling drive motor 1 in the manner described above is described.

[0029] When oil is supplied from EOP 10, oil circulation begins. The oil exchanges heat with the coolant of the vehicle's cooling system 50 in heat exchanger 30, and the oil temperature decreases. Then, drive motor 1 is cooled by the oil injected through the cooling pipe 11 of drive motor 1. After cooling drive motor 1, the oil moves to reducer 70, where impurities are removed by oil filter 72 located in reducer 70, and returns to EOP 10. This cycle is repeated.

[0030] Typically, oil is injected into the coils, which are the main heat-generating parts of the drive motor. This pressurized oil supply satisfactorily cools the stator. However, without this dispersion method, the rotor may not be adequately cooled. When the rotor is not sufficiently cooled, thermal deformation may occur; for example, the permanent magnets in the rotor may demagnetize, or the molded parts may be damaged.

[0031] Temperature sensors used to measure the temperature of drive motors are typically installed in the stator coils, which makes it difficult to measure the temperature of the rotor, and thermal deformation often occurs before the overheat protection logic designed to protect the drive motor from overheating takes effect.

[0032] In cases involving dispersed types, a separate cooling line is required to supply oil from the EOP, and an EOP with advanced capabilities may be needed to account for pressure losses and the amount of oil in the separate line.

[0033] When the drive motor is being cooled, a certain amount of oil supplied to it is wasted instead of being used for cooling. Depending on the winding method of the drive motor's coils, particularly in the case of hairpin motors, the coils are arranged at an angle opposite the stator core. As a result, oil injected from the cooling pipes impacts the angled coils, causing the oil to fly outwards along the coils without penetrating them, resulting in wasted oil.

[0034] In this case, it was found that more oil was wasted at the rear of the drive motor than at the front. This is because, unlike the front which is completely occupied by the coils, the rear lacks the space within the coils that oil could have penetrated through due to the molded structure and insulating sheets. As a result, the injected oil bounces off the coils and flies towards the housing, thus the actual amount of oil used for cooling becomes less than the supplied amount, thereby reducing cooling efficiency.

[0035] This disclosure provides a cooling structure configured to recover waste oil that is not used at the rear of the drive motor and to utilize the recovered oil by dispersing the oil via the motor shaft.

[0036] Figure 2 This is an axial cross-sectional view of a drive motor for a vehicle according to the present disclosure.

[0037] Reference Figure 2 According to this disclosure, the drive motor 1 for a vehicle includes a stator 20, a rotor 40, a hollow shaft 60, and a housing 80.

[0038] The stator 20 includes a stator core 22 and a coil 24 wound on the stator core 22.

[0039] The rotor 40 is rotatably disposed radially inside the stator 20 and includes a rotor core and permanent magnets formed on the rotor core.

[0040] The hollow shaft 60 is located radially inside the rotor 40 and is configured to rotate with the rotor 40. The hollow shaft 60 is rotatably coupled to the housing 80 via a bearing (not shown). The end of the hollow shaft 60 is open, and a certain gap is provided between the end of the hollow shaft 60 and the housing 80.

[0041] A through hole 62 is formed on the hollow shaft 60. The through hole 62 serves as a dispersion hole in the dispersion type. The through hole 62 allows communication between the interior and exterior of the hollow shaft 60. Multiple through holes can be arranged at predetermined intervals around the hollow shaft 60. More specifically, the through hole 62 can be positioned radially aligned with the coil 24 and the rotor 40.

[0042] The housing 80 houses the stator 20, rotor 40, and hollow shaft 60, and is coupled to the hollow shaft 60 via bearings. In one embodiment of this disclosure, the housing 80 includes a collector 82 and a channel 84. The collector 82 and the channel 84 may be formed in the inner wall of the housing 80.

[0043] like Figure 3 As shown, the collector 82 is recessed on the upper side of the housing. In one embodiment of this disclosure, the collector 82 includes a recessed portion 182 and a protruding portion 282.

[0044] The recessed portion 182 and the protruding portion 282 form a receiving space with an open upper portion and serve as a collector 82 configured to collect oil that bounces off the coil 24 and is wasted. The recessed portion 182 protrudes approximately horizontally from the inner surface or inner wall of the upper side of the housing 80, and the protruding portion 282 extends approximately upward from the recessed portion 182.

[0045] Channel 84 is designed to deliver oil collected by collector 82 to hollow shaft 60 for axial dispersion. Channel 84 extends from collector 82 toward the central portion of housing and allows collector 82 and hollow shaft 60 to communicate with each other. Channel 84 may be formed along the inner surface of housing 80 in a vertical direction. In one form of this disclosure, channel 80 includes a first descending portion 184, a switching channel 284, and a second descending portion 384.

[0046] refer to Figure 4The first descending portion 184 is arranged such that it is guided generally downward or radially inward along the inner wall of the housing 80. A switching channel 284 extends from the first descending portion 184 to change the flow path axially, i.e., from a vertical direction to a horizontal direction, and simultaneously extends the flow path along the circumference of the hollow shaft 60. The switching channel 284 also extends simultaneously in both the axial and circumferential directions of the hollow shaft 60, such that the first descending portion 184 advances horizontally by switching from a vertical direction. The switching channel 284 is configured to communicate with the hollow shaft 60. Additionally, the switching channel 284 may include a second descending portion 384 extending downward from the switching channel 284 and configured to communicate with the hollow shaft 60. In one embodiment of this disclosure, the second descending portion 384 is configured to communicate with the open end of the hollow shaft 60.

[0047] Reference Figure 5 The process of cooling a drive motor according to this disclosure is described.

[0048] Oil supplied from the EOP is injected into the drive motor 1 through cooling pipe 11 (path P1). In one embodiment of this disclosure, cooling pipe 11 is disposed on the upper side of housing 80, configured to spray oil onto the lower side of housing 80, and configured to extend axially along the drive motor to inject oil into the front and rear portions of the drive motor. Specifically, the oil is configured to be guided to coil 24. Some of the injected oil permeates into the gaps between the coil portions and cools coil 24, while some of the injected oil bounces back towards housing 80 without permeating into the gaps between the coil portions (path P2). The bounced oil collides with housing 80 and then flows downward along the interior of housing 80, or collides with the top of housing 80 and then falls (path P3). The oil flowing along path P3 is collected in collector 82. The oil collected in collector 82 flows along a first descending portion 184 (path P4) and flows along a second descending portion 384 via switching channel 284 and enters hollow shaft 60 (path P5).

[0049] The rotation of the hollow shaft 60 causes the oil to be dispersed through the through hole 62, thereby cooling the rotor 40 by axial dispersion, and the coils 24 of the stator 20 are additionally cooled (path P6).

[0050] In this disclosure, oil can be supplied to the hollow shaft 60 using the force of the fluid generated by the height difference based on gravity and Bernoulli's principle, without increasing or changing the EOP capability. According to this disclosure, axial dispersion can be used to utilize the oil ejected into the housing 80, thereby achieving rotor cooling with the same oil volume and the same EOP capability, as well as additional cooling to the stator.

[0051] The drive motors for vehicles equipped with the aforementioned cooling structure offer excellent cooling performance. Specifically, the cooling performance of the drive motor can be significantly improved without using large amounts of oil. Oil injected from the cooling pipes and wasted due to collisions with the coils is reused for axial dispersion, allowing for a greater oil supply to cool both the rotor and stator under the same flow conditions. This is done because, although the EOP (Electrical Operating Flow) remains the same magnetic flux, the reuse of waste oil through axial dispersion provides additional cooling to both the rotor and stator coils.

[0052] Furthermore, as the amount of oil supplied from the EOP increases due to the rise in the temperature of the drive motor, the amount of oil wasted after colliding with the coils also increases. Then, through axial dispersion, the amount of oil that can be reused to cool the inner sides of the stator and rotor also increases, thereby improving cooling performance under excessively high temperature conditions.

[0053] The drive motor for vehicles according to this disclosure can improve vehicle driving performance. Since a temperature sensor detects overheating of the drive motor due to increased internal temperature of the stator coils, overheat protection logic is employed. Consequently, the vehicle's driving performance deteriorates due to a decrease in the output power of the drive motor. However, according to this disclosure, although the amount of oil injected into the stator is the same under the same oil supply conditions, the interior of the stator and rotor is cooled by reused oil, thereby mitigating the limitation on the reduction in output power and achieving more stable driving performance.

[0054] Furthermore, according to the present invention, demagnetization of permanent magnets in the rotor of the drive motor can be suppressed. Oil wasted due to collisions with the coils is collected to cool the rotor, thus avoiding the risk of demagnetization of the permanent magnets due to increased rotor temperature and reducing maintenance costs caused by demagnetization-related malfunctions.

[0055] According to this disclosure, the cost of the EOP (Energy Optimizer) can be reduced and the potential travel distance increased. When using a conventional axial dispersion structure, the EOP requires an additional load to supply oil to a separate pipeline for dispersion. In cases where the EOP output is insufficient due to pressure losses in the additional pipeline, an EOP with a higher capacity may be required. However, according to this disclosure, oil is supplied through the reuse of waste oil and oil pressure without additional EOP load or changes in EOP capacity. Therefore, cooling performance can be improved under the same EOP or with the same oil supply, and for the same cooling performance, an EOP with a lower capacity or a lower EOP load can be used, thereby reducing the cost of the EOP and the electronic load due to the reduced EOP load, thus potentially increasing the potential travel distance.

[0056] It is evident from the foregoing that, according to this disclosure, a drive motor with excellent cooling performance for use in vehicles can be provided.

[0057] According to this disclosure, a drive motor for vehicles with a simple structure and excellent cooling performance can be provided.

[0058] According to this disclosure, a drive motor for a vehicle that can provide improved driving performance can be provided.

[0059] According to this disclosure, a drive motor for vehicles that can suppress the demagnetization of permanent magnets in the rotor can be provided.

[0060] It should be understood that this disclosure is not limited to the above-described form and figures, and that various alternatives, modifications and alterations can be devised by those skilled in the art without departing from the technical spirit of this disclosure.

Claims

1. A drive motor for a vehicle, the drive motor comprising: Stator, including coils; The rotor is rotatably disposed inside the stator; A hollow shaft, disposed inside the rotor and configured to rotate with the rotor, and the hollow shaft includes a plurality of through holes; and A housing is configured to house the stator, the rotor, and the hollow shaft, and the housing includes a channel formed in the inner wall of the housing; The channel is configured to allow communication between the upper side of the inner wall and the interior of the hollow shaft and to allow oil to flow within the channel; and A cooling pipe, disposed axially along the upper side of the housing and configured to inject oil into the housing, is located above the stator, wherein the channel is configured to receive oil ejected from the cooling pipe that bounces back from the coil.

2. The drive motor according to claim 1, wherein, The housing also includes a collector recessed in the upper side of the inner wall and configured to communicate with the channel.

3. The drive motor according to claim 2, wherein, The channel extends radially inward from the collector along the inner wall within the housing.

4. The drive motor according to claim 3, wherein, The hollow shaft includes an open end configured to communicate with the channel.

5. The drive motor according to claim 2, wherein, The collector includes: A recessed portion protrudes horizontally from the inner wall of the housing; and The protruding portion extends upward from the recessed portion.

6. The drive motor according to claim 2, wherein, The channel includes: A first descending portion is formed on the inner wall of the housing and extends downward from the collector; and A switching channel extends axially and circumferentially from the first descending portion along the hollow shaft, and the switching channel is configured to switch the direction of oil flowing out from the first descending portion.

7. The drive motor according to claim 6, wherein, The switching channel also includes a second descending portion extending downward from the switching channel.

8. The drive motor according to claim 7, wherein, The hollow shaft includes an open end configured to communicate with the second descending portion.

9. The drive motor according to claim 8, wherein, The oil introduced into the interior of the hollow shaft through the second descending section is dispersed to the rotor and the stator through the plurality of through holes.

10. The drive motor according to claim 1, wherein, The oil is delivered to the cooling pipe under pressure generated by an electric oil pump.

11. The drive motor according to claim 1, wherein, The plurality of through holes are configured to communicate between the interior and exterior of the hollow shaft, and the plurality of through holes are arranged at predetermined distances from each other along the circumference of the hollow shaft.

12. The drive motor according to claim 11, wherein, The oil flows through the channel into the interior of the hollow shaft and disperses towards the rotor and the stator through the plurality of through holes.

13. A drive motor for a vehicle, the drive motor comprising: Stator, including coils wound around the stator; The rotor is rotatably disposed inside the stator, and the rotor includes permanent magnets disposed around the rotor; A hollow shaft is disposed inside the rotor and configured to rotate with the rotor, and the hollow shaft includes a plurality of through holes spaced apart from each other at a predetermined distance along the circumference of the hollow shaft. A housing is configured to house the stator, the rotor, and the hollow shaft, and the housing includes a channel formed in the inner wall of the housing; The channel is configured to allow communication between the upper side of the inner wall and the interior of the hollow shaft and to allow oil to flow within the channel; and A cooling pipe, disposed axially along the upper side of the housing and configured to inject oil into the housing, is located above the stator, wherein the channel is configured to receive oil ejected from the cooling pipe that bounces back from the coil.

14. The drive motor according to claim 13, wherein, The plurality of through holes are located on the hollow shaft, wherein the hollow shaft coincides radially with the coil or the plurality of permanent magnets.

15. The drive motor according to claim 14, wherein, The oil is sprayed radially outward from the hollow shaft through the plurality of through holes.

16. The drive motor according to claim 14, wherein, The oil injected into the housing is directed toward the coil.

17. The drive motor according to claim 14, wherein, The oil is delivered to the cooling pipe under pressure generated by an electric oil pump.

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