Cooling structure for an electric unit

Abstract

The utility model provides a kind of electric unit capable of improving strength or NV characteristic together with cooling performance.The electric unit is housed with motor, transmission mechanism that transmits the torque of motor output and controller that controls motor in the inside of liquid-tight structure shell, wherein, shell has reinforcing rib and the thin plate portion between each other, oil for lubricating motor or transmission mechanism is enclosed in the inside of shell, heat exchanger (10) is arranged between oil and cooling water to exchange heat and cool the inside of shell in the thin plate portion, heat exchanger is equipped with multiple fins (14) vertically erected relative to thin plate portion, and the flow path of any one of oil and cooling water is divided.

Description

Technical Field

[0001] This utility model relates to a structure for cooling an electric unit such as a motor (electric generator) having a motor or a motor having a power generation function, a transmission mechanism for transmitting its output torque, and a power control unit (PCU). Background Technology

[0002] Such electric units are sometimes mounted in vehicles as a driving force source. In this case, the available space is quite limited, so they are usually housed as a whole in a defined housing, or the mechanical drive part and the electrical control part are housed separately in housings as separate units, and these units are connected and housed in the engine compartment, etc. On the other hand, when mounted in electric vehicles as a driving force source, vibration or noise must be minimized to ensure ride comfort. This vibration or noise is mainly generated in the moving parts, but can sometimes be aggravated by resonance or harmonic resonance. Patent Document 1 describes a vehicle-mounted unit in which an electrical unit and an electromechanical unit, each housed in a housing, are connected by an air gap, and a sealing part is provided at the connection point between the electrical unit and the electromechanical unit to provide a surface seal between them. By adopting such a structure, the generation of resonance in the air gap and the associated deterioration of vibration and noise can be suppressed.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2022-152851

[0004] The electric motor unit is typically housed within a casing, as described above. This casing is preferably as lightweight as possible while still meeting the required strength requirements. While reducing the casing wall thickness is considered for weight reduction, the electric motor unit contains movable mechanical parts such as a motor and transmission mechanism inside the casing. Therefore, the generation and transmission of power cause membrane vibration in a portion of the casing, which can potentially be a major cause of deterioration in so-called NV characteristics. In the configuration described in Patent Document 1, even if resonance in the air layer can be suppressed, reductions in other vibrations and noise cannot be achieved.

[0005] Furthermore, the internal structure of the electric motor unit is a sealed structure for oil lubrication, etc. Consequently, heat is generated due to Joule losses, iron losses, and friction in moving parts of the electrical components, requiring aggressive cooling. In vehicle-mounted structures, systems utilizing airflow for cooling the electric motor unit are considered. However, installing new equipment on the electric motor unit for cooling creates new challenges, becoming a major cause of vibration and noise degradation, as well as an increase in the size and weight of the electric motor unit. Utility Model Content

[0006] This invention was developed in response to the aforementioned technical issues, and its purpose is to improve strength or NV characteristics in conjunction with cooling performance.

[0007] To achieve the above objectives, this utility model provides a cooling structure for an electric unit. The electric unit houses an electric motor, a transmission mechanism for transmitting the torque output of the electric motor, and a controller for controlling the electric motor inside a liquid-tight housing. The cooling structure of the electric unit is characterized in that the housing has reinforcing ribs and thin plate portions between the reinforcing ribs. Oil for lubricating the electric motor or the transmission mechanism is sealed inside the housing. A heat exchanger is provided in the thin plate portion. The heat exchanger cools the interior of the housing by exchanging heat between the oil and cooling water. The heat exchanger has multiple fins that stand vertically relative to the thin plate portion and divide the flow path of either the oil or the cooling water.

[0008] According to this invention, a portion of the housing housing containing an electric motor, a transmission mechanism, and a controller that generate heat through operation is reinforced with reinforcing ribs, and the portion between these reinforcing ribs forms a thin plate section that is prone to membrane vibration. A heat exchanger is provided in this thin plate section to exchange heat with cooling water inside the housing, thereby cooling the interior of the housing. This heat exchanger has multiple fins that divide the flow paths for oil or cooling water, thus increasing the heat exchange area. Furthermore, these fins are arranged vertically relative to the thin plate section, thus functioning in the same way as the ribs that improve the rigidity of the thin plate section. That is, not only can the cooling performance be improved by the heat exchanger, but the rigidity can also be increased, thereby improving strength or NV characteristics. Attached Figure Description

[0009] Figure 1 This is a block diagram that conceptually represents the structure of the electric unit involved in this utility model.

[0010] Figure 2 This is a three-dimensional diagram representing an example of a heat exchanger.

[0011] Figure 3 This is a simplified diagram showing the appearance of the electric motor unit.

[0012] Figure 4 This is a partial perspective view showing a portion of the shell with reinforcing ribs and thin plates.

[0013] Explanation of reference numerals in the attached figures

[0014] 1…Electric unit; 2, 3…Electric generator (motor); 4…Transmission mechanism; 6…Housing; 7…Oil; 8…Radiator; 9…Cooling water; 10…Heat exchanger; 11…Flow path; 12…Main body; 13…Base plate; 14…Fin; 15…Cover; 16…Inlet; 17…Outlet; 18…Reinforcing rib; 19…Thin plate. Detailed Implementation

[0015] Next, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the embodiments described below are merely one example of implementing the present invention and do not limit the scope of the invention.

[0016] As an example, the electric unit in the embodiment of this utility model is a device mounted on a vehicle and serving as a driving force source. If an example is conceptually shown, then... Figure 1 The block diagram is shown. The example shown here has two motors (electric motors): a first electric generator 2 and a second electric generator 3, and a transmission mechanism 4 that increases or decreases the torque output from these motors 2 and 3 and outputs it. A power control unit (PCU) 5 is provided as a controller for controlling the output torque and power generation (charge to the battery) of these motors 2 and 3. Furthermore, a battery (not shown) that supplies power to the motors 2 and 3 and charges the battery with power generated by either motor 2 or 3 is mounted on the vehicle along with the electric unit 1.

[0017] Motors 2 and 3, transmission mechanism 4, and PCU5 are housed inside housing 6, forming an electric unit 1 as a whole. Housing 6 is a liquid-tight structure, configured to seal oil 7, which lubricates motors 2 and 3 and transmission mechanism 4, inside housing 6, allowing the oil 7 to circulate in rotating and sliding parts.

[0018] The PCU5 includes an inverter and a converter (not shown), which is water-cooled to maintain the temperature of the converter below a specified temperature. Specifically, the vehicle has a radiator 8 that dissipates heat to external air such as driving winds, and the radiator 8 is configured to circulate cooling water 9, whose temperature has been lowered by passing through the radiator 8, back to the PCU5 to cool the inverter, converter, and other converters.

[0019] Figure 1 The electric unit 1 shown also includes a heat exchanger 10 that cools the oil 7 and the interior of the casing 6 by exchanging heat between the oil 7 and the cooling water 9. Figure 2An example of a heat exchanger 10 is schematically shown. The heat exchanger 10 shown here has flow paths 11 formed inside a rectangular container. The main body 12 is a thin, box-shaped structure, inside which a plurality of fins 14 are arranged parallel to each other at certain intervals, vertically erected on the inner surface of the base plate 13. These fins 14 are plates extending linearly from one of opposing inner wall surfaces towards the other, with their front ends separated from the other inner wall surface. This separation point is opposite to the left and right sides of adjacent fins 14. At the separation points from these other inner wall surfaces, the flow paths of the fins 14 are connected to each other. Furthermore, the main body 12 has an opening on the side opposite to the base plate 13, and a cover 15 is provided to close this opening. Thus, the fins 14 divide and form a serrated flow path 11. An inlet 16 connected to one end of the flow path 11 and an outlet 17 connected to the other end are provided on the side of the main body 12.

[0020] Figure 3 A brief description of the appearance of the electric unit 1 is provided. The motors 2 and 3 are housed in the largest volume portion of the housing 6, and the transmission mechanism 4 is housed in the portion extending axially from this portion. The PCU5 is housed at the top. The housing 6 is a casting made of materials such as aluminum alloy. Figure 4 As shown in the enlarged view, in order to reduce weight, reinforcing ribs 18 are provided in necessary locations, and the portions between these reinforcing ribs 18 form thin plate portions 19.

[0021] The heat exchanger 10 is disposed on the thin plate portion 19. The heat exchanger 10 is positioned on the side of the reinforcing ribs 18 protruding from them (e.g., the outer surface side), which is the portion between the reinforcing ribs 18. If it is on the opposite side (e.g., the inner surface side), it can also span across the portion of the two thin plate portions 19, crossing the portion corresponding to the reinforcing ribs 18. Furthermore, the heat exchanger 10 is configured such that its base plate portion 13 is in close contact with or integrated with the thin plate portion 19. Therefore, the fins 14 are integrated with the thin plate portion 19 in a vertically upright state relative to it. As a result, the fins 14 function to reinforce the thin plate portion 19, increasing the rigidity or strength of the thin plate portion 19.

[0022] When the heat exchanger 10 is located on the outer surface of the housing 6, the oil 7 sealed inside the housing 6 exchanges heat with the heat exchanger 10 via the thin plate portion 19. Conversely, since the cooling water 9 flows inside the heat exchanger 10, the heat of the oil 7 is removed by the cooling water 9, and both the oil 7 and the interior of the housing 6 are cooled. Alternatively, when the heat exchanger 10 is located on the inner surface of the housing 6, the heat exchanger 10 is immersed in the oil 7, or the oil 7 flows in contact with the outer surface of the heat exchanger 10. On the other hand, inside the heat exchanger 10, the cooling water 9 contacts not only the bottom plate portion 13 of the heat exchanger 10 but also the fins 14, and flows along the flow path 11, removing heat from the heat exchanger 10. Therefore, the heat exchange area relative to the cooling water 9 is increased, enabling efficient cooling of the oil 7 and the interior of the housing 6.

[0023] As described above, according to the embodiments of the present invention, the heat exchange area is expanded by the fins 14 for heat exchange, thus enabling efficient cooling of the electric unit 1. Furthermore, the fins 14 increase the rigidity or strength of the thin plate portion 19, which is prone to membrane vibration, thereby suppressing the vibration of the thin plate portion 19 or the housing 6 and improving the NV characteristics of the electric unit 1.

[0024] Furthermore, this invention is not limited to the structure of the above-described embodiments. In short, it is possible to use fins for heat exchange that reinforce the thin plate portion of the shell. For example, when heat exchangers 10 are arranged between the reinforcing ribs 18, the reinforcing ribs 18 and the thin plate portion 19 between them can be used as the sidewall portion and bottom plate portion of the main body portion 12. Fins are vertically erected on this thin plate portion, and a cover portion is provided to cover the fins to form a heat exchanger. Additionally, in this invention, the number of heat exchangers can be multiple. Furthermore, in this invention, oil can flow inside the heat exchanger, and the heat exchanger can be cooled from the outside using cooling water.

Claims

1. A cooling structure for an electric motor, wherein the electric motor houses an electric motor, a transmission mechanism for transmitting the torque output of the electric motor, and a controller for controlling the electric motor within a liquid-tight housing. Its features are, The housing has reinforcing ribs and thin plate portions between the reinforcing ribs. The interior of the housing is sealed with oil for lubricating the electric motor or the transmission mechanism. A heat exchanger is provided in the thin plate section, which exchanges heat between the oil and cooling water to cool the interior of the housing. The heat exchanger has multiple fins that stand vertically relative to the thin plate and divide the flow path of either the oil or the cooling water.

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