Flat wire motor stator oil cooling structure

Abstract

This invention discloses a stator oil-cooling structure for a flat wire motor, comprising a stator core and stator slots. The stator core includes a middle section core and a spray section core. The middle section core includes an oil inlet channel, a flow channel, and a keyway. The oil inlet channel is formed by rotating and stacking stator laminations, each lamination having a rectangular hole. The spray section core includes a guide channel and an oil spray hole. The guide channel is formed by rotating and stacking stator laminations, each lamination having a T-shaped hole and an elliptical hole. The oil inlet channel, flow channel, guide channel, and oil spray hole are interconnected, forming an oil circuit. This invention features a spray section at the end of the stator core, enabling direct spraying of cooling oil to the stator winding ends, ensuring good cooling performance, significantly reducing the complexity and manufacturing cost of the oil spraying system. The oil spray hole is positioned close to the bottom of the stator slot and axially facing the winding ends, allowing the oil to cover the entire winding ends and maximizing the reduction of winding end temperature.

Description

Technical Field

[0001] This invention belongs to the field of oil-cooled motor technology, and specifically relates to an oil-cooled stator structure for a flat wire motor. Background Technology

[0002] With the accelerated electrification transformation of the global automotive industry, drive motors are continuously developing towards "high efficiency, high power density, and high reliability." Efficient and reliable stator cooling technology is one of the decisive factors for flat-wire motors to achieve a leap in power density and safe operation. Compared to traditional water jacket cooling, direct oil cooling technology can directly contact the heated stator windings and core, resulting in lower thermal resistance and higher heat exchange efficiency, making it the preferred solution for addressing the high heat flux density heat dissipation problem of flat-wire motors.

[0003] One existing solution involves constructing the cooling circuit using additional components independent of the stator core, such as an oil injection ring, oil injection pipe, and external oil sleeve. This solution introduces numerous connection interfaces, sealing surfaces, and assembly steps, increasing material and manufacturing costs. Furthermore, it introduces the potential for coolant leakage under long-term high-vibration conditions of the motor.

[0004] To address this issue, a Chinese invention patent, "A Stator Assembly, Motor, Electric Assembly, and Vehicle" (Patent Publication No.: CN119030201A), proposes a solution that constructs a cooling circuit on the housing. However, this solution requires machining complex flow channels within the housing, resulting in high processing costs. Furthermore, this solution first cools the housing and the outer ring of the stator, requiring heat conduction through the iron core, leading to significant thermal resistance and the potential for hot spots within the iron core. This results in low cooling efficiency and an inability to effectively dissipate the heat generated by high heat flux density. Additionally, the oil exiting the housing cannot directly contact the winding ends for cooling, potentially causing localized overheating at the ends.

[0005] Chinese Invention Patent: An oil circuit device for an oil-cooled motor that can improve cooling effect (Patent Publication No.: CN119483118A). This solution uses two or three laminations to form a centripetal oblique spraying oil circuit. The spraying position is greatly affected by the oil pump flow rate, the motor installation tilt angle and the slope of the vehicle. Under harsh working conditions, the oil cannot be accurately sprayed at the highest point of the winding heat generation, resulting in an unsatisfactory cooling effect.

[0006] Chinese Invention Patent: A Cooling Structure for an Electric Motor Stator, an Oil-Cooled Motor, and a Vehicle (Patent Publication No.: CN120810986A). This design features an oil guide channel and a stepped oil spray channel on the stator core. A circumferentially surrounding oil inlet groove is located in the center of the stator core. The cooling medium enters the oil guide channel through the oil inlet groove in the center of the stator core and is then sprayed obliquely towards the stator windings at both ends of the stator core through the stepped oil spray channel. This invention utilizes three types of stator laminations that are continuously rotated and stacked to form the guide channel and the stepped oil spray channel, allowing the cooling medium to be concentrated and sprayed obliquely towards the stator windings, effectively cooling the stator windings. However, it also has some drawbacks:

[0007] 1. The internal flow channels and stepped, inclined oil injection holes are formed by continuously rotating and stacking three types of stator laminations. This process itself leads to a cumbersome and costly core manufacturing process. The inherently small diameter of the oil injection holes not only makes them prone to clogging but also increases the oil pressure drop. Furthermore, due to their inclined design, it is difficult to visually inspect and clean blockages during the manufacturing process. In addition, the number and layout of the oil injection holes are strictly constrained by the number of motor slots, resulting in insufficient design freedom and flexibility.

[0008] 2. The compact and limited-volume internal oil channel structure created by this design results in both high flow resistance for the cooling medium and a limited effective contact area for heat exchange with the stator core. These two factors combined prevent the cooling medium from achieving sufficient and uniform heat exchange with the stator surface, thus hindering further improvements in the overall heat dissipation efficiency of the stator.

[0009] Furthermore, a Chinese invention patent, "A Stator Heat Dissipation Structure for Oil-Cooled Motors" (Patent Publication No.: CN118100483A), employs a design scheme to improve cooling efficiency by creating slots on the outer circumference of the stator core, thereby increasing the contact area between the cooling oil channels and the core. The cooling oil fully fills all the oil channels, achieving a larger heat exchange area. However, this slotted outer circumference design also has corresponding drawbacks:

[0010] Because the slots reduce the effective contact area between the iron core and the motor housing, a larger interference fit is required to ensure sufficient bonding force and prevent relative slippage under high torque output conditions. This increased interference directly leads to increased assembly stress on the housing. To avoid strength risks, it is often necessary to increase the housing thickness or use higher-strength materials, which increases manufacturing costs and structural complexity to some extent. Summary of the Invention

[0011] The main objective of this invention is to provide a flat wire motor stator oil-cooling structure, which solves the problems of low heat exchange efficiency and insufficient cooling effect caused by the limited contact area between the cooling oil circuit and the stator core in existing oil-cooled motors; complex core manufacturing process and high production cost caused by the complex rotation and stacking of multiple laminations required to realize the oil channel in the centripetal spray structure; and excessive mold development cost caused by the use of multiple types of laminations in the stator core to realize the cooling function.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a stator oil-cooling structure for a flat wire motor, comprising a stator core and stator slots, wherein the stator slots are filled with winding copper wires, the stator core comprising a middle section core and a spray section core, the middle section core comprising an oil inlet channel, a flow channel, and a flat keyway, the oil inlet channel being formed by rotating and stacking stator laminations, the stator laminations being provided with rectangular holes, the spray section core comprising a guide channel and an oil spray hole, the guide channel being formed by rotating and stacking stator laminations, the stator laminations being provided with T-shaped holes and elliptical holes, the oil inlet channel, the flow channel, the guide channel, and the oil spray hole being interconnected to form an oil circuit.

[0013] Furthermore, the spray section core is located on both sides of the middle section core, and the spray section core is located at both ends of the stator core.

[0014] Furthermore, the oil injection hole is close to the bottom of the stator slot and axially aligned with the end of the stator winding.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. This invention eliminates the traditional independent oil injection ring and sets a jetting stack at the end of the stator core. This stack and the motor housing together form a highly efficient flow channel, which can directly spray the cooling oil to the end of the stator winding. This design not only ensures good cooling performance, but also significantly reduces the complexity and manufacturing cost of the oil injection system, while making the overall structure of the motor more compact.

[0017] 2. This invention features several rectangular holes on the outer side of the stator laminations in the middle section of the iron core. These holes are stacked using a specific rotation angle and are interconnected to form a network of internally connected cooling oil channels. This design extends the flow path of the cooling oil inside the iron core, increasing the contact area and contact time between the oil and the iron core. Simultaneously, the strong turbulence generated by the oil flowing through the intersecting channels further enhances the convective heat transfer effect, thereby significantly improving the heat dissipation efficiency of the stator iron core and increasing the power density of the motor.

[0018] 3. The stator end spraying function of this invention is formed by rotating a single stator lamination at a single angle. This structure cleverly guides the oil to complete radial and axial flow, ultimately achieving uniform spraying of the oil onto the entire stator winding. This solution achieves a complex flow guiding effect with a minimalist structure, eliminating the need for repeated stacking at multiple angles to form complex stepped spray holes, greatly simplifying the design and manufacturing process. The oil spray hole is designed to be close to the bottom of the stator slot and axially aligned with the winding end, allowing the oil to cover the entire winding end and minimizing the temperature at the winding end.

[0019] 4. The entire stator core of this invention is composed of only two types of stator laminations, which minimizes the types and number of lamination dies, simplifies the production process, improves assembly efficiency, and has a simple and compact overall structure that is easy to install. This not only reduces production costs but also enhances the applicability of the design to different types of motors.

[0020] 5. The stator outer circle of this invention is close to a complete circle, with no excessive toothed oil passages, which increases the contact area with the housing. Under the same interference fit, it can withstand a larger torque without slippage, increasing the safety margin and reducing the interference fit, thus reducing the difficulty of production and manufacturing. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the stator structure of a flat wire motor stator oil-cooling structure according to the present invention;

[0022] Figure 2 This is a schematic diagram of the core structure of the middle section of the stator oil-cooling structure of a flat wire motor according to the present invention;

[0023] Figure 3 This is a schematic diagram of the spray section core structure of the stator oil-cooling structure of a flat wire motor according to the present invention;

[0024] Figure 4 This is a schematic diagram of the stator oil passage cross-section flow direction of a flat wire motor stator oil cooling structure according to the present invention.

[0025] In the diagram: 1. Injection hole; 2. Guide channel. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] See Figure 1 , Figure 2 , Figure 3 and Figure 4This invention discloses a stator oil-cooling structure for a flat wire motor, comprising a stator core and stator slots. The stator slots are filled with winding copper wires. The stator core includes a middle section core and a spray section core, with the spray section cores located on both sides of the middle section core and at both ends of the stator core. Further, the middle section core includes an oil inlet channel, a flow channel, and a keyway. The oil inlet channel is formed by rotating and stacking stator laminations, and the stator laminations have rectangular holes. Further, the spray section core includes a guide channel 2 and an oil spray hole 1. The guide channel 2 is formed by rotating and stacking stator laminations, and the stator laminations have T-shaped holes and elliptical holes. The oil inlet channel, flow channel, guide channel 2, and oil spray hole 1 are interconnected, forming an oil circuit. Cooling oil enters the iron core through the oil inlet channel and flows outwards through the flow channel, making full contact with the iron core. During the flow, the constant change in the direction of the channel generates strong disturbances, which destroys the thermal boundary layer and significantly enhances the convective heat transfer efficiency. This effectively removes the heat generated by the iron core losses. The oil that has completed the iron core cooling flows into the spray section at both ends and is introduced into the oil spray hole 1 through the rectangular hole to realize the spray function of the stator end. The oil spray hole 1 is designed to be close to the bottom of the stator slot, axially facing the end of the stator winding, and at a close distance. The oil can accurately cover the entire end of the winding, achieving the effect of the entire winding end being immersed in the oil.

[0028] This invention eliminates the traditional independent oil injection ring and sets up a jetting stack at the end of the stator core. This stack, together with the motor housing, forms a highly efficient flow channel that can directly spray cooling oil to the end of the stator winding. This design not only ensures good cooling performance but also significantly reduces the complexity and manufacturing cost of the oil injection system, while making the overall structure of the motor more compact.

[0029] Several rectangular holes are formed on the outer side of the stator laminations in the middle section of the iron core. These holes are stacked by rotating at a specific angle and are interconnected to form an internally connected network of cooling oil channels. This design extends the flow path of the cooling oil inside the iron core, increasing the contact area and contact time between the oil and the iron core. Simultaneously, the strong turbulence generated by the oil flowing through the intersecting channels further enhances the convective heat transfer effect, thereby significantly improving the heat dissipation efficiency of the stator iron core and increasing the motor's power density.

[0030] The stator end spraying function is achieved by rotating a single stator lamination at a single angle. This structure cleverly guides the oil to flow radially and axially, ultimately achieving uniform spraying of the oil onto the entire stator winding. This solution achieves a complex flow-guiding effect with a minimalist structure, eliminating the need for complex stepped spray nozzles formed by repeated stacking at multiple angles, greatly simplifying the design and manufacturing process. The oil spray hole 1 is positioned close to the bottom of the stator slot, axially facing the winding end, allowing the oil to cover the entire winding end and minimizing the temperature at the winding end.

[0031] The entire stator core is composed of only two types of stator laminations, which minimizes the types and number of lamination dies, simplifies the production process, improves assembly efficiency, and makes the overall structure simple and compact and easy to install. This not only reduces production costs but also enhances the applicability of the design to different motor models.

[0032] The stator's outer circle is nearly a full circle with few toothed oil passages, increasing the contact area with the housing. Under the same interference fit, it can withstand greater torque without slippage, increasing the safety margin and reducing the interference fit, thus simplifying manufacturing.

[0033] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0034] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flat wire motor stator oil cooling structure, characterized by: It includes a stator core and a stator slot. The stator slot is filled with winding copper wire. The stator core includes an intermediate section core and a spray section core. The intermediate section core includes an oil inlet channel, a flow channel, and a flat keyway. The oil inlet channel is formed by rotating and stacking stator laminations. The stator laminations are provided with rectangular holes. The spray section core includes a guide channel (2) and an oil spray hole (1). The guide channel (2) is formed by rotating and stacking stator laminations. The stator laminations are provided with T-shaped holes and elliptical holes. The oil inlet channel, the flow channel, the guide channel (2), and the oil spray hole (1) are interconnected to form an oil circuit.

2. The flat wire motor stator oil cooling structure of claim 1, wherein: The spray section core is located on both sides of the middle section core, and the spray section core is located at both ends of the stator core.

3. The flat wire motor stator oil cooling structure of claim 1, wherein: The oil injection hole (1) is close to the bottom of the stator slot and is axially aligned with the end of the stator winding.

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