DC Motor Filter Unit for Automotive Wiper EMC Noise
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Solution Overview
Problem
Automotive brush type DC motors generate significant electromagnetic noise, failing to meet stringent Original Equipment Manufacturer (OEM) electromagnetic compatibility (EMC) specifications, with existing solutions being costly and ineffective.
Innovation Solution
A DC motor arrangement featuring a filter unit with metallic plates and capacitors connected to a printed circuit board, forming a Faraday cage-like structure to reduce electromagnetic noise, utilizing inductors and capacitors in a symmetrical arrangement to minimize parasitic inductance and enhance EMC performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brush type DC motors are used in automotive wipers, then the motor can provide reliable mechanical power, but it generates significant electromagnetic noise that fails to meet OEM EMC specifications
Solution Approach 1:
A filter unit is introduced as an intermediary component between the DC motor and the electrical system. This filter unit includes capacitors connected to power lines and a metallic plate structure that acts as a mediator to capture and dissipate electromagnetic noise, allowing the motor to operate reliably while meeting EMC specifications
Solution Approach 2:
The metallic plate structure of the filter unit captures electromagnetic noise (harmful factor) and converts it into a controlled electrical discharge through the capacitors, transforming the harmful electromagnetic interference into a manageable electrical phenomenon that can be safely dissipated
2Object-generated harmful factors
If existing EMC solutions are implemented, then electromagnetic noise is reduced, but the cost increases significantly
Solution Approach 1:
The filter unit uses inexpensive capacitors and a simple metallic plate structure (can be made from standard aluminum housing material) instead of costly specialized EMC components. The capacitors are standard electronic components that are cheap and readily available, making the solution cost-effective
Solution Approach 2:
The metallic plate structure serves multiple functions: it acts as part of the motor housing structure, provides electromagnetic shielding, and serves as a mounting surface for the capacitors. This multi-functionality eliminates the need for separate EMC shielding components, reducing overall cost
3Object-generated harmful factors
If existing EMC solutions are implemented, then electromagnetic noise is reduced, but the effectiveness is insufficient
Solution Approach 1:
The filter unit applies electromagnetic filtering locally at the motor level, with capacitors connected directly to each power line and the metallic plate positioned close to the motor windings. This localized approach effectively addresses EMC issues at their source, providing superior noise reduction compared to distant filtering solutions
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 and cost-efficiently reduces electromagnetic noise, ensuring compliance with OEM EMC specifications by creating a robust electromagnetic shield around the DC motor.
Implementation Method 1
The filter unit comprises a first filter means connected in series with the first power line and a second filter means connected in series with the second power line
Implementation Method 2
a first portion of a metallic plate connected to the first filter means; a second portion of a metallic plate connected to the second filter means; wherein the first portion of the metallic plate and the second portion of the metallic plate are electrically connected to a common substrate
Implementation Method 3
the first filter means are connected to the first power line by the interposition of a first inductor and the second filter means are connected to the second power line by the interposition of a second inductor
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention is referred to a DC motor arrangement for an automotive wiper. This DC motor arrangement comprises a first portion of a housing (1) and a second portion of a housing (12), a DC motor (2) located inside the first portion of the housing (1), the DC motor (2) comprising a first power line (2a) and a second power line (2b), and a filter unit (30) associated to the DC motor (2). The filter unit (30) comprises: a first filter means (3) connected in series with the first power line (2a), a second filter means (4) connected in series with the second power line (2b), a first portion (5) of a metallic plate (56) connected to the first filter means (3), a second portion (6) of a metallic plate (56) connected to the second filter means (4). The first portion (5) of the metallic plate (56) and the second portion (6) of the metallic plate (56) are electrically connected to a common substrate (8), and respectively connected in series to the second portion of the housing (12).