DC Motor Circuit Board Mounting via Spring Lugs
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Solution Overview
Problem
Existing direct-current motors for motor vehicle assemblies face challenges in simple mounting and grounding of circuit boards with interference suppression components, particularly when using plastic end shields, as they require additional assembly steps like soldering and increased manufacturing effort.
Innovation Solution
A DC motor design featuring a base plate with radially opposite flange eyes for screwing into the motor housing, combined with spring lugs and arms for positive locking and grounding, allowing the circuit board to be slid into place without soldering or screws, using conductive stamped sheet metal or electrically conductive end shields for grounding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soldering is used to connect the circuit board to the motor housing, then reliable electrical connection is achieved, but manufacturing complexity and assembly time increase
Solution Approach 1:
The patent replaces the soldering process (thermal/mechanical system) with a mechanical clamp connection system. The circuit board is secured to the motor housing using a clamp mechanism that provides both mechanical support and electrical grounding without requiring soldering, thus reducing assembly complexity while maintaining connection reliability.
Solution Approach 2:
The patent introduces a clamp connection as an intermediary element between the circuit board and the motor housing. This clamp serves as a mediator that establishes both mechanical attachment and electrical connection, eliminating the need for direct soldering while ensuring reliable grounding for electromagnetic compatibility.
2Ease of manufacture
If plastic end shields are used, then manufacturing cost is reduced, but grounding capability is compromised
Solution Approach 1:
The patent employs composite material construction where the end shield integrates both plastic (for cost reduction and insulation) and conductive elements (for grounding). The clamp connection mechanism incorporates conductive components that establish electrical grounding paths even when the end shield itself is made of non-conductive plastic material, thus maintaining grounding capability while benefiting from lower manufacturing costs.
Solution Approach 2:
The patent segments the grounding function from the structural end shield. Instead of requiring the entire end shield to be conductive, the design separates the structural plastic component from the grounding function, which is achieved through dedicated conductive clamp connections. This allows the end shield to be made of inexpensive plastic while grounding is provided by separate conductive elements.
3Reliability
If additional assembly steps like soldering are required, then connection reliability is improved, but productivity decreases
Solution Approach 1:
The patent replaces the multi-step soldering process with a single mechanical clamp connection operation. This substitution eliminates heating, cooling, and inspection steps associated with soldering, allowing for rapid assembly while maintaining reliable electrical and mechanical connections, thus significantly improving productivity.
Solution Approach 2:
The clamp connection is designed to be pre-assembled or pre-positioned, allowing the circuit board to be quickly attached to the motor housing in a single operation. This preliminary preparation of the connection mechanism enables fast assembly without requiring skilled soldering operations, thereby increasing production speed.
Data Source
Figure 1
AI summary
The motor (10) has an end shield (18) axially limiting the motor, and a printed circuit board (44) on which bypass capacitors (46) are located and comprising a central aperture (48) through which a drive shaft (14) of the motor is projected. The board comprises two passage apertures (50) through which tongue-shaped terminals (24) of the motor is projected. A punching metal sheet (26) produces a ground connection and comprises spring tabs (36) over which the board is electrically and mechanically connected with the metal sheet by a form closure.