Motor Inverter Transistor Mounting for Cooling and Service Access
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Solution Overview
Problem
Conventional arrangements for mounting power transistors in electric machines face serviceability issues, making it inconvenient and time-consuming to access the transistors for repair, replacement, and maintenance, while also complicating heat dissipation.
Innovation Solution
The introduction of a frame element with urging elements that simultaneously urge multiple power transistors against the bottom wall of the inverter housing, improving heat dissipation and providing a more accessible and serviceable design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional metallic leaf spring elements are used to urge power transistors against the bottom wall, then heat dissipation is achieved, but serviceability deteriorates due to complex disassembly requirements
Solution Approach 1:
The mounting structure is divided into separate functional modules: the inverter housing with bottom wall for heat dissipation, the printed circuit board assembly for electronics, and the power transistor assembly with integrated mounting tabs. This segmentation allows the power transistors to be accessed and replaced independently by simply removing the PCB assembly, while the bottom wall remains fixed for continuous heat dissipation function.
2Force
If multiple leaf springs are used to secure power transistors, then adequate urging force is provided, but device complexity increases
Solution Approach 1:
The mounting tabs are integrally formed with the power transistor housing as a single piece, eliminating the need for separate leaf springs and screws. The tabs directly engage with slots in the bottom wall, providing both mechanical retention and urging force through the inherent elasticity of the tab-bottom wall interface, thereby reducing part count and assembly complexity.
Solution Approach 2:
The mounting tabs are designed with elastic deformation capability, allowing them to automatically provide urging force against the bottom wall without external spring elements. The tabs self-adjust to maintain contact pressure, and the entire mounting mechanism can be quickly released by disengaging the tabs from the slots, enabling self-service maintenance.
3Temperature
If power transistors are mounted against the bottom wall for heat dissipation, then thermal management is improved, but access to transistors becomes difficult
Solution Approach 1:
The system is segmented into a stationary heat dissipation component (bottom wall) and a movable electronic assembly (PCB with power transistors). This allows the electronic assembly to be easily removed for access to transistors, while the bottom wall remains in place to maintain thermal management capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances serviceability by simplifying access to the power transistors and improves heat dissipation, thereby preventing damage to the transistors and ensuring efficient performance.
Implementation Method 1
the bottom wall being in contact with refrigerant received in the motor accommodating space of the motor housing on other side thereof acts as a heat sink
Implementation Method 2
The power transistors are urged against a bottom wall of the inverter housing for heat dissipation from the power transistors
Implementation Method 3
The frame element is provided with urging elements adapted to urge corresponding power transistors towards the bottom wall
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An electric machine (100) for a motor vehicle includes an electric motor (125), a machine (115) and an inverter (140). The machine (115) is driven by the electric motor (125). The inverter (140) is received and held in an inverter housing (130) and is adapted to process and regulate electrical power being supplied to the electric motor (125) from an external power source. The inverter (140) comprises a printed circuit board (141) and power transistors (142) for converting a High Voltage (HV) Direct Current (DC) to a three-phase Alternating Current (AC) that drives the electric motor (125). The inverter (140) further comprises a frame element (144) disposed between the printed circuit board (141) and a bottom wall (131a) of the front head (131). The frame element (144) is provided with urging elements (145) adapted to urge the corresponding power transistors (142) towards the bottom wall (131a).