Power Control Unit Case Helmholtz Resonance Reduction
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Solution Overview
Problem
The existing power control unit (PCU) designs for electric vehicles face increased vibration noise due to Helmholtz resonance, which is exacerbated by the airspace between the PCU case and the transaxle case, compromising the rigidity and mounting efficiency of components.
Innovation Solution
A PCU case design with a tubular shape and a beam member that connects long-side side walls, eliminating the lower cover and using the transaxle case surface as the lower surface, thereby eliminating airspace and maintaining rigidity through a plate-shaped beam member that divides the case into upper and lower chambers for efficient component mounting and electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a separate lower lid is used to constitute the lower surface of the PCU case, then the PCU case can be assembled with components, but an airspace is created between the PCU case and transaxle case that induces Helmholtz resonance and increases vibration noise
Solution Approach 1:
The patent merges the lower lid with the transaxle case by making the lower lid identical to or integrated with the transaxle case lower surface. This eliminates the airspace between the PCU case and transaxle case, preventing Helmholtz resonance and reducing vibration noise while maintaining component mounting capability.
2Object-affected harmful factors
If the lower lid is integrated with the transaxle case to eliminate airspace, then vibration noise from Helmholtz resonance is reduced, but the rigidity of the PCU case may be compromised
Solution Approach 1:
The patent introduces a partition wall that divides the PCU case interior into upper and lower chambers. This segmentation reinforces the PCU case structure, maintaining rigidity even when the lower lid is integrated with the transaxle case to eliminate airspace and prevent Helmholtz resonance.
3Object-affected harmful factors
If the PCU case structure is modified to eliminate airspace and add partition walls, then vibration noise is reduced and rigidity is maintained, but the complexity of the case structure increases
Solution Approach 1:
The partition wall serves multiple functions: it reinforces the PCU case structure to maintain rigidity, divides the interior into upper and lower chambers for organized component placement, and works with the integrated lower lid to eliminate airspace and prevent Helmholtz resonance. This multi-functionality reduces the need for additional separate structural elements.
4Productivity
If components are distributed across upper and lower chambers divided by a partition wall, then component mounting efficiency is improved and electrical connections can be established through the partition, but the partition wall structure adds complexity
Solution Approach 1:
The partition wall includes a through-hole that serves as an intermediary pathway for electrical connections between components in the upper and lower chambers. This allows components to be distributed across both chambers for efficient mounting while maintaining necessary electrical connectivity without requiring complex external wiring arrangements.
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 configuration effectively reduces vibration noise from Helmholtz resonance while maintaining the rigidity of the PCU case and allowing for efficient component mounting, enhancing the structural integrity and noise reduction.
Implementation Method 1
a beam member that extends inside the case main body along a short-side direction of the case main body, connects the pair of long-side side walls to each other, and is formed in a plate shape so as to divide the inside of the case main body into an upper chamber and a lower chamber
Implementation Method 2
an intermediate opening that is formed so as to at least partially adjoin the beam member and provides communication between the upper chamber and the lower chamber
Implementation Method 3
a fastening part that is formed so as to surround the lower surface-side opening and fastened to the surface of the transaxle case
Implementation Method 4
an upper cover that constitutes the upper surface of the PCU case and covers the upper surface-side opening
Data Source
AI summary
A PCU case of a power control unit includes a case main body that has an upper surface-side opening and a lower surface-side opening and is formed in a tubular shape with a rectangular cross-section, and an upper cover that covers the upper surface-side opening. The case main body includes a fastening part that is formed so as to surround the lower surface-side opening and fastened to a surface of a transaxle case, and this surface of the transaxle case doubles as a lower surface of the PCU case. The case main body includes a plate-shaped beam member that extends along a short-side direction, connects a pair of long-side side walls to each other, and divides the inside of the case main body into an upper chamber and a lower chamber, and an intermediate opening that provides communication between the upper chamber and the lower chamber.