JP-2026074531-A - Electric unit

Abstract

[Problem] To provide an electric unit that suppresses heat transfer from the transaxle case to the power control unit, while also suppressing an increase in the overall size of the unit. [Solution] An electric unit 1 comprises a transaxle case 3 housing a transaxle including a motor and gear train, and a PCU case 2 housing a power control unit 4 that controls the power supplied to the motor, with the PCU case 2 having a cylindrical connecting portion 3b protruding from the transaxle case 3. The PCU case 2 has an opening 2e that opens toward the space inside the connecting portion 3b and is fixed to the end of the connecting portion 3b. At least a part of the power control unit 4 is arranged inside the connecting portion 3b and is fixed to the PCU case 2 with a predetermined gap between it and the transaxle case 3. [Selection Diagram] Figure 1

Inventors

• 殿畑 厚

Assignees

• トヨタ自動車株式会社

Dates

Publication Date

20260507

Application Date

20241021

Claims (1)

1. An electric unit comprising a transaxle case housing a transaxle including a motor and gear train, and a PCU case fixed to the transaxle case housing a power control unit that controls the power supplied to the motor, It is equipped with a cylindrical connecting portion that protrudes from the transaxle case, The PCU case has an opening that faces the space inside the connection portion and is fixed to the end of the connection portion. An electric unit characterized in that at least a portion of the power control unit is arranged inside the connection portion and fixed to the PCU case with a predetermined gap between it and the transaxle case.

Description

This invention relates to an electric unit comprising a transaxle including a motor and gear train, and a power control unit for controlling the motor. Patent Document 1 describes an integrated electric unit in which a PCU case housing a power control unit for controlling the motor is fixed to the upper part of a transaxle case containing a transaxle including a motor and differential mechanism. To suppress the influence of radiant heat from the transaxle case on the power control unit, this integrated electric unit is provided with a cylindrical connection portion protruding from the upper side of the transaxle case, ribs with heat dissipation functions are provided inside the connection portion, and the PCU case is fixed to the upper end of the connection portion. The ribs are arranged in a grid pattern within the inner area of the connection portion, and their tips are configured to protrude outside the connection portion. Japanese Patent Publication No. 2023-035537 This is a schematic cross-sectional view showing an example of an electric unit in an embodiment of this invention. This invention will be described based on the embodiments shown in the figures. Note that the embodiments described below are merely examples of how the present invention can be implemented and do not limit the invention. The electric unit in this embodiment of the invention can be applied to a vehicle having a transaxle that includes a motor functioning as a driving force source and a gear train that transmits the motor's torque to the drive wheels. Figure 1 shows an enlarged cross-sectional view illustrating an example of the electric unit in this embodiment of the invention. The electric unit 1 shown in Figure 1 is constructed by combining a PCU case 2 that houses a power control unit (hereinafter referred to as PCU) 4 that controls the motor, and a transaxle case 3 that houses the aforementioned transaxle. In the example shown in Figure 1, the PCU 4 is composed of, for example, a converter that boosts and buckles the output voltage of an energy storage device (not shown), and an inverter that converts the DC voltage of the energy storage device to an AC voltage. The PCU 4 may also include other electronic components, such as a DC-DC converter that adjusts the voltage applied to electrical equipment of auxiliary devices installed in the vehicle. Figure 1 shows that the PCU 4 comprises four components: a first component 4a, a second component 4b, a third component 4c, and a fourth component 4d. The PCU case 2 comprises a mounting plate 2a, a cylindrical first side wall portion 2b extending upward from the outer peripheral edge of the mounting plate 2a in Figure 1, a substantially tapered second side wall portion 2c extending downward from near the outer peripheral edge of the mounting plate 2a in Figure 1, and a flange portion 2d projecting outward from the lower end of the second side wall portion 2c. The flange portion 5a of the cover 5, which has a trapezoidal cross-section, is fixed to the upper end of the first side wall portion 2b by bolts (not shown), for example. Within the upper space 6 enclosed by the cover 5 and the mounting plate 2a and second side wall portion 2c of the PCU case 2, the first component 4a of the PCU 4 is positioned on the upper surface of the mounting plate 2a in Figure 1. On the other hand, a cylindrical connecting portion 3b is formed on the top plate portion 3a of the transaxle case 3, extending upward in Figure 1. The upper end of the connecting portion 3b is fixed to the flange portion 2d of the PCU case 2 by a bolt (not shown), for example. This forms a housing portion 7 between the PCU case 2 and the transaxle case 3, which houses the second component 4b, the third component 4c, and the fourth component 4d of the PCU 4. Specifically, the housing section 7 is formed by the internal space 3c of the connection section 3b of the transaxle case 3 and an opening 2e formed on the inside of the second side wall 2c of the PCU case 2, which opens toward the internal space 3c. In the housing section 7, the second component 4b of the PCU 4 is directly attached to the lower surface of the mounting plate 2a of the PCU case 2 in Figure 1, within the opening 2e of the PCU case 2. The third component 4c of the PCU 4 has a flange-shaped fastening portion 4e that protrudes from one of its sides toward the connection portion 3b of the transaxle case 3. The fastening portion 4e is fixed to a part of the flange portion 2d of the PCU case 2 via a buffer 4f using bolts 8. The buffer 4f is preferably formed from an elastic resin material, thereby allowing it to function as both a heat insulating material and a cushioning material. Thus, the third component 4c does not directly contact the second component 4b, but is supported only by the flange portion 2d of the PCU case 2 via the buffer 4f. The fourth component 4d of the PCU 4 is slightly smaller in width compared to the second component 4b and the third component