Axle drive phase junction box cooling

Abstract

The invention relates to cooling of an axle drive phase junction box. The invention relates to a thermal connection for an electric drive system, comprising: at least one copper layer; at least one ceramic layer in contact with the copper layer; the coil winding is a component of the electric driving system, and the coil winding is provided with a plurality of wires; a hot spot at an end winding of each of the plurality of wires; a bus bar connected to each end winding near the hot spot; and a junction box housing in which each end winding and the bus bar are located. The copper layer is in contact with each end winding near the hot spot, and the ceramic layer is in contact with the junction box housing. The second copper layer is in contact with the junction box housing such that the ceramic layer is disposed between the copper layer and the second copper layer. And the connecting box shell is a part of the shell of the speed reducer.

Description

Technical Field

[0001] This invention relates to a thermal connector, a component of an electric drive system, which reduces the temperature at the location of the connection between the end winding of one or more conductors of the stator coil winding and the busbar. Background Technology

[0002] Modern high-power-density automotive electric drive systems typically consist of an electric motor (e-machine), a reduction gear, and an inverter. Axle-driven components are usually located in the engine compartment, and the connecting boxes are typically housed in a separate housing within the reduction gear. Electric drive systems must operate correctly under various conditions, such as city driving, highway driving, uphill / downhill driving, or repeated acceleration / braking. Therefore, the operating temperature of the electric drive system components must always remain below their corresponding limit temperatures; otherwise, derating will occur, limiting the performance of the electric drive system.

[0003] During the various operating conditions described above, one or more components of the electric drive system may experience extreme temperature increases. One of these components is the connection between the end windings of one or more conductors of the stator winding and the busbar. This connection is located in the phase junction box between the inverter and the motor. During assembly, the ends of one or more conductors of the stator winding are soldered to the busbar, reducing the cross-sectional area of ​​each conductor end. This reduced cross-sectional area leads to an increase in ohmic losses and, therefore, a significant increase in the local temperature of the solder joint during operation of the electric drive system. The area at the end of each conductor exhibiting this increase in local temperature is commonly referred to as a "hotspot." For example, this temperature increase can be as high as 35°C higher than the average temperature of other parts of the stator winding. This temperature increase also affects the choice of plastic material used for the housing surrounding the busbar.

[0004] One proposed solution to reduce the temperature of the stator end winding portion with a reduced cross-sectional area is to expose the phase connection box to guide oil cooling during gearbox operation. However, this will create the problem of oil wetting within the motor and inverter housings (i.e., oil leakage into the motor or inverter). Furthermore, potential chemical reactions between the oil and the coating material on the stator coil winding conductors could also be a problem.

[0005] Therefore, there is a need to reduce the temperature at the connection point (i.e., hot spot) between the end winding of one or more conductors of the stator coil winding and the busbar of the electric drive system. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a thermal connection between the hot spot area of ​​the conductor and the housing of the phase connection box in order to achieve temperature reduction and thus prevent overheating of the hot spot, the conductor being a component of the stator end winding.

[0007] This objective can be achieved by the electric drive system with thermally connected components according to independent claim 1 and the method according to independent claim 8. Preferred embodiments are given in the dependent claims.

[0008] In embodiments, the thermal connector of the present invention includes the use of a separate housing of a phase connector box located within a reducer housing, and the thermal connector includes the use of one or more layers of copper and ceramic plates to connect hot spot areas (busbars, phase conductors surrounding solder joints, etc.) to the housing of the phase connector box to provide conductive heat extraction from the hot spot.

[0009] The thermal connector of this invention improves the sustained and peak performance of the electric drive system. Furthermore, the improved cooling reduces the temperature of hot spots, which in turn leads to a reduction in corresponding ohmic losses, thereby improving system efficiency.

[0010] Heat extraction from the housing of the connecting box occurs through the interaction between the oil and the housing. This heat transfer depends on both the oil temperature and the operating speed of the reducer. During operation, the temperature of the housing of the connecting box is typically similar to that of the oil due to the oil splashing against the housing wall.

[0011] In an embodiment, the surface heat transfer area of ​​the phase connection box near the hot spot can be increased by using additional pins or ribs connected to the phase connection box, such as... Figure 4 The diagram in the middle is shown.

[0012] Without a solid connection between the hot spot of the stator end winding and the housing of the phase connection box, the connection between the stator end winding and the busbar is only surrounded by air, and therefore the temperature of the hot spot cannot be substantially reduced during the operation of the electric drive system; in fact, the oil temperature changes as a result. Due to the heat transfer via conduction through copper and ceramic plates, combined with the use of the thermal connector of the present invention, any change in the oil temperature has an immediate effect on the corresponding temperature of the hot spot.

[0013] In one embodiment, the effect of forced air convection in the engine compartment can be used to further reduce the temperature of the connecting box, as a result of a corresponding reduction in the temperature of the oil.

[0014] In an embodiment, the present invention is a thermal connector for an electric drive system, having at least one copper layer; at least one ceramic layer in contact with the copper layer; a coil winding, which is a component of the electric drive system, the coil winding having a plurality of wires; a hot spot located at the end winding of each of the plurality of wires; a busbar connected to each end winding near the hot spot; and a connector housing, each end winding and busbar being located within the connector housing. The copper layer is in contact with each end winding near the hot spot, and the ceramic layer is in contact with the connector housing.

[0015] In one embodiment, the second copper layer contacts the housing of the connecting box, such that the ceramic layer is disposed between the copper layer and the second copper layer.

[0016] In this embodiment, the connecting box housing is a component of the housing of the reducer of the electric drive system.

[0017] In one embodiment, one or more fins are integrally formed as components connecting the housing.

[0018] In one embodiment, the second thermal connector contacts the hot spot and the sidewall of the connector housing.

[0019] In one embodiment, the connecting box housing includes a first sidewall and a second sidewall, the second sidewall being located on the opposite side of the connecting box housing relative to the first sidewall. A first thermal connector contacts the first sidewall, and a second thermal connector contacts the second sidewall.

[0020] In this embodiment, each end winding is located at the end of a corresponding one of a plurality of conductors.

[0021] In an embodiment, the present invention is a method for reducing the temperature of a hot spot in a junction box housing of an electric drive system, comprising the steps of: providing at least one thermal connector; providing a coil winding, which is a component of the electric drive system, the coil winding having a plurality of wires; providing a hot spot located at the end winding of each of the plurality of wires; providing a busbar connected to each end winding near the hot spot; and providing a junction box housing. In another embodiment, the method comprises the steps of: connecting each end winding to the busbar such that components of each end winding and the busbar are located within the junction box housing; and connecting the hot spot to the junction box housing via at least one thermal connector, such that heat is transferred away from the hot spot via the thermal connector.

[0022] Further applications of the invention will become apparent from the detailed description provided below. It should be understood that, although preferred embodiments of the invention have been indicated, the detailed description and specific examples are for illustrative purposes only and are not intended to limit the scope of the invention. Attached Figure Description

[0023] The invention will be more fully understood from the detailed description and the accompanying drawings, in which:

[0024] Figure 1 This is a schematic diagram of an electric drive system with a thermal connector according to an embodiment of the present invention;

[0025] Figure 2 This is an enlarged perspective view of a plurality of end windings of a stator according to an embodiment of the present invention. Some of the plurality of end windings of the stator are connected to a busbar, which is a component of an electric drive system having thermal connections.

[0026] Figure 3 This is a schematic diagram of the thermal connection between the hot spot and the connecting box housing according to an embodiment of the present invention; and

[0027] Figure 4 This is a schematic diagram of an alternative embodiment of the thermal connection between the hot spot and the connecting box housing according to an embodiment of the present invention. Detailed Implementation

[0028] The following description of preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention or its application or use.

[0029] A schematic diagram of an embodiment of an electric drive system having a thermal connector for a phase connection box is shown in Figure 1 The diagram is shown in the middle, essentially denoted by 10. System 10 includes an electric motor or motor (essentially denoted by 12), which is mechanically connected to a gearbox (essentially denoted by 14). Motor 12 is also electrically connected to an inverter (essentially denoted by 16). Motor 12 and inverter 16 are housed in housing 18, and gearbox 14 is partially housed in housing 18.

[0030] The motor 12 includes a rotor 20 surrounded by a stator 22. The rotor 20 is mounted to a shaft 24, and the shaft 24 is connected to a reducer 14. The reducer 14 includes a plurality of gears (not shown) that are driven by the motor 12 via the shaft 24. The reducer 14 drives one or more output shafts 26a, 26b.

[0031] The motor 12 also includes coil windings connected to the stator 22. The coil windings are made of individual conductors 30a, 30b and include multiple winding heads (generally shown as 28). One or more of the individual conductors 30a, 30b extend into a junction box housing (generally shown as 32), where the junction box housing 32 is a component of the reducer 14. The end of each conductor 30a, 30b is referred to as an end winding, and each end winding is electrically connected to a corresponding busbar, which in this embodiment is a first busbar 34a, where the first busbar 34a is electrically connected to the inverter 16, such as... Figure 1 and Figure 2The diagram shows that each busbar 34a, 34b, 34c can be electrically connected to conductors 30a, 30b either directly or through the use of connecting elements or the like. Also within the scope of the invention, conductors 30a, 30b and / or other individual conductors of the coil windings can be soldered to the first busbar 34a or other busbars electrically connected to the inverter 16. In the illustrated embodiment, the first busbar 34a is at least partially disposed in and supported by the busbar holder 36, which also supports other busbars 34b, 34c, such as... Figure 2 The diagram shows conductors 30a, 30b, the first busbar 34a, and additional busbars 34b, 34c serving as a phase connection box located inside the connection box housing 32.

[0032] The welded connectors that connect conductors 30a and 30b to their corresponding busbars (or connecting elements) (e.g., the first busbar 34a) are located at the end windings of conductors 30a and 30b. During assembly, the welding process reduces the cross-sectional area of ​​the end windings, leading to temperature concentration or "hot spots" during operation. The thermal connector of this invention promotes a reduction in temperature at the location of the hot spots in the end windings. The thermal connector comprises multiple layers. (Reference) Figure 3 The first layer is a first copper layer 38, the second layer is a ceramic layer 40, and the third layer is a second copper layer 42. The first copper layer 38 is in contact with one or more of the copper conductors 30a and 30b near the hot spot (i.e., near the welded connection between the conductors 30a, 30b and the first busbar 34a). The ceramic layer 40 is connected to the copper layers 38 and 42 and is disposed between the copper layers 38 and 42, and the second copper layer 42 is in contact with the surface 44 of the junction box housing 32.

[0033] Formed integrally with housing 18 is a separate housing or reducer housing 46. Reducer housing 46 surrounds the various components of reducer 14, thereby fluidly isolating reducer housing 46 from the remainder of the components of electric drive system 10. Fluid is provided within reducer housing 46 to provide lubrication for the gears of reducer 14 and to control the internal temperature of reducer 14. Figure 1 As shown in the figure, the connecting box housing 32 is a component of the reducer housing 46, such that the connecting box housing 32 and the reducer housing 46 have at least one common sidewall, and in the illustrated embodiment, they have two common sidewalls 48a and 48b, and surface 44 is a component of one of the sidewalls 48a.

[0034] During operation, the fluid in the reducer housing 46 is agitated and / or circulated, causing the fluid to contact the sidewall 48a, reducing the temperature of the sidewall 48a, and thus also reducing the temperature of the copper layers 38, 42 and the ceramic layer 40. This reduction in temperature of the copper layers 38, 42 and the ceramic layer 40 also reduces the temperature of hot spots, or the temperature at the location of the welded connections at the end windings of the conductors 30a, 30b. Heat transfer depends on the temperature of the fluid and the rotational speed of the gears in the reducer 14. Any change in the temperature of the fluid has an immediate effect on the corresponding temperature of the hot spots due to conductive heat transfer through the copper layers 38, 42 and the ceramic layer 40, as well as convective heat transfer between the oil and the housing.

[0035] In another embodiment, a second thermal connector with a ceramic plate disposed between two copper plates may be used. The first copper plate of the second thermal connector contacts one or more of the copper wires 30a and 30b near the hot spot, and the second copper plate of the second thermal connector contacts the second sidewall 48b. In other embodiments, one or more thermal connectors may also include only two layers, such as a copper layer 38 and a ceramic layer 40.

[0036] exist Figure 4 The figure illustrates another embodiment of the invention, wherein similar reference numerals denote similar elements. In this embodiment, a plurality of protrusions or fins 50 are attached to the inner surface of the sidewall 48a, where the fins 50 are parallel to the gears in the reducer 14.

[0037] In another alternative embodiment, the effect of forced air convection in the engine compartment can be used to additionally reduce the temperature of the junction box housing by the corresponding decrease in oil temperature.

[0038] The present invention relates to at least one thermal connection between the end windings of one or more conductors 30a, 30b and the sidewall 48a of a connecting housing 32, where each end winding is connected to a corresponding busbar, such as a first busbar 34a. The thermal connection includes a first copper layer 38 in contact with each end winding of the corresponding conductors 30a, 30b; a second copper layer 42 in contact with the sidewall 48a of the connecting housing 32; and a ceramic layer 40 disposed between and in contact with the first and second copper layers 38 and 42. Each end winding is electrically connected to and can be soldered to the corresponding busbar (e.g., the first busbar 34a). During the soldering process, the cross-sectional area of ​​the end winding decreases, resulting in the formation of hot spots on the end windings during operation of the electric drive system. During operation of the electric drive system 10, the temperature of the end winding at the location of the hot spot is typically significantly higher than the rest of the coil winding. Heat is transferred away from the hot spot through the first copper layer 38, the ceramic layer 40, and the second copper layer 42.

[0039] The description of this invention is merely exemplary in nature, and therefore variations that do not depart from the essential points of the invention are intended to fall within the scope of the invention. Such variations are not considered to depart from the spirit and scope of the invention.

Claims

1. A thermal connector for an electric drive system (10), comprising: - At least one copper layer (38, 42); - At least one ceramic layer (40) is in contact with the at least one copper layer (38, 42); - A coil winding, which is a component of the electric drive system (10), the coil winding having a plurality of conductors (30a, 30b); - Hot spot, the hot spot being located at the end winding of each of the plurality of conductors (30a, 30b); - Busbar (34a), which is connected to each end winding near the hot spot; - Connecting box housing (32), each end winding and the busbar (34a) are located in the connecting box housing (32); - wherein at least one copper layer (38, 42) is in contact with each end winding near the hot spot, and at least one ceramic layer (40) is in contact with the connector housing (32).

2. The thermal connector for an electric drive system (10) according to claim 1, wherein the at least one copper layer (38, 42) further comprises: - A second copper layer (42) is in contact with the connecting box housing (32); - wherein the at least one ceramic layer (40) is disposed between the at least one copper layer (38) and the second copper layer (42).

3. A thermal connector for an electric drive system (10) according to any one of the preceding claims, wherein, The connecting box housing (32) is a component of the housing of the reducer (14) of the electric drive system (10).

4. The thermal connector for an electric drive system (10) according to any one of the preceding claims further comprises one or more fins (50) that are integrally formed as a component of the connector housing (32).

5. The thermal connector for an electric drive system (10) according to any one of the preceding claims, further comprising a second thermal connector in contact with the hot spot and the sidewall (48b) of the connector housing (32).

6. The thermal connector for an electric drive system (10) according to any one of the preceding claims, wherein the connector housing (32) further comprises: First sidewall (48a); as well as The second sidewall (48b) is located on the opposite side of the connecting box housing (32) relative to the first sidewall (48a); The first thermal connector contacts the first sidewall (48a), and the second thermal connector contacts the second sidewall (48b).

7. A thermal connector for an electric drive system (10) according to any one of the preceding claims, wherein each end winding is located at the end of a corresponding one of the plurality of conductors (30a, 30b).

8. A method for reducing the temperature of hot spots in the junction box housing (32) of an electric drive system (10), comprising the steps of: - Provide at least one thermal connection; - Provide a coil winding, which is a component of the electric drive system (10), the coil winding having a plurality of wires (30a, 30b); - Provide hotspots located at the end windings of each of the plurality of conductors (30a, 30b); - A busbar (34a) is provided, the busbar (34a) being connected to each end winding near the hot spot; - Provides a connecting box housing (32); - Connect each end winding to the busbar (34a) such that the components of each end winding and the busbar (34a) are located in the connection box housing (32); - The hot spot is connected to the connection box housing (32) via the at least one thermal connector; - Transfer heat away from the hot spot through the at least one thermal connector.

9. The method of claim 8, further comprising the following steps: - Provide a first copper layer (38), the first copper layer (38) being a component of the at least one thermal connector, the first copper layer (38) contacting each end winding; - A second copper layer (42) is provided, which is a component of the at least one thermal connector, and the second copper layer (42) contacts the connector housing (32); and - Provide a ceramic layer (40), which is a component of the at least one thermal connector, the ceramic layer (40) being disposed between the first copper layer (38) and the second copper layer (42); Heat is transferred away from the hot spot through the first copper layer (38), the ceramic layer (40), and the second copper layer (42), and transferred to the connecting box housing (32).

10. The method according to any one of the preceding claims further comprises the following steps: - A component in which one or more fins (50) are integrally formed as the connecting box housing (32); - Heat is dissipated away from the connecting box housing (32) through the one or more fins (50).

11. The method according to any one of the preceding claims further comprises the following steps: - Provide a second thermal connector that contacts the hot spot and the connection box housing (32); - Transfer heat away from the second hot spot through the second thermal connector.

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