Overmolded Metal Bracket for Plastic Cover Retention
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Solution Overview
Problem
Current electric pump arrangements for vehicle transmissions face packaging violations due to the thickness of plastic covers and fasteners, which prevents them from fitting within the limited profile space required, especially when using plastic covers that need to be sealed and corrosion-resistant.
Innovation Solution
A low profile electric pump arrangement is achieved by over molding a metal bracket into a plastic cover, which engages the inverter housing to securely hold the cover in place, eliminating the need for conventional fasteners and ensuring a sealed and corrosion-resistant design that fits within the designated packaging profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional retention methods (screws and bolt limiters) are used to attach the plastic cover, then the cover can be securely retained, but the thickness of the cover and fasteners causes packaging violations and prevents fitting within limited profile space
Solution Approach 1:
The metal bracket is overmolded directly into the plastic cover, merging two separate components (retention mechanism and cover) into a single integrated structure. This eliminates the need for separate fasteners and reduces overall profile thickness while maintaining secure retention through the bracket's engagement with the inverter housing
Solution Approach 2:
The metal bracket is nested within the plastic cover during the overmolding process, with the bracket positioned inside the cover's mold cavity. This nesting approach allows the bracket to be embedded in the cover structure, reducing the external profile while preserving the retention function
2Reliability
If plastic cover thickness is increased to accommodate fasteners and ensure proper sealing, then retention and sealing are improved, but the overall profile exceeds the packaging profile line
Solution Approach 1:
The retention function is moved from a thickness dimension (requiring thick walls for fasteners) to a lateral engagement dimension, where the metal bracket extends sideways to engage with the inverter housing. This dimensional shift allows thin-walled plastic covers to achieve secure retention without increasing profile thickness
3Strength
If metal brackets are used for retention, then strength and retention are improved, but corrosion resistance is reduced compared to plastic
Solution Approach 1:
The solution uses a composite structure combining metal bracket (for strength) with plastic cover (for corrosion resistance). The overmolding process creates a bonded interface between the metal bracket and plastic cover, forming a hybrid component that leverages the advantages of both materials: the metal provides structural strength while the plastic provides corrosion protection
Solution Approach 2:
The plastic material acts as an intermediary between the metal bracket and the corrosive environment. The plastic cover encapsulates the metal bracket, isolating it from exposure to fluids and corrosive elements, while still allowing the bracket to perform its retention function through engagement with the housing
Data Source
AI summary
A low profile electric pump arrangement having a motor housing connected to a pump element of a transmission for a vehicle. An inverter housing connected to the motor housing and has a where an electronics control unit (ECU) connects through the inverter housing to selectively supply power to the motor within the motor housing. The recess and the ECU are covered and sealed off from the elements by a plastic cover. In order to obtain a low profile of the electric pump arrangement so it can fit within a desired packaging line on a transmission casing a metal bracket is over molded into the plastic cover. The metal bracket has at least one exposed surface that engages the inverter housing to hold the plastic cover onto the inverter housing in a position so that the plastic cover covers and seals the ECU and recess at the second side of the inverter housing.