Rotor Position Sensor Shielding in Compact Brake Drive Housings
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Solution Overview
Problem
In drive devices with electric machines, the proximity of the circuit board to electrically conductive lines within the housing causes capacitive interference, affecting the functionality of the sensor unit, particularly the electronic components like ASICs.
Innovation Solution
A shielding sheet made of copper material is radially arranged around the circuit board, providing effective shielding and is fastened to the housing or rotor, establishing an electrical ground connection to dissipate capacitive effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the circuit board is arranged in the housing to save installation space, then the drive device becomes more compact, but the circuit board is in close proximity to electrically conductive lines causing capacitive interference with the sensor unit
Solution Approach 1:
A shielding sheet is introduced as an intermediary element between the circuit board and the electrically conductive lines. The shielding sheet, made of electrically conductive material, acts as a mediator that blocks capacitive coupling and electromagnetic interference from reaching the sensor unit while allowing the compact housing arrangement to be maintained.
Solution Approach 2:
The shielding sheet converts the potentially harmful capacitive effects into a controlled electromagnetic shield. By placing the conductive shielding material between the interference source and the sensor, the harmful capacitive coupling is transformed into a beneficial shielding effect that directs and contains electromagnetic fields.
2Object-affected harmful factors
If the shielding sheet is made of copper material for effective shielding, then capacitive interference is reduced, but the device complexity increases
Solution Approach 1:
The shielding sheet is implemented as a thin, flexible conductive film rather than a rigid bulky structure. This thin-film approach provides effective electromagnetic shielding while minimizing the added complexity and space requirements of the shielding structure.
Solution Approach 2:
The shielding effectiveness is optimized by adjusting parameters such as the conductivity, thickness, and geometric configuration of the shielding sheet. By carefully selecting these parameters, effective interference protection is achieved with minimal additional device complexity.
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
The shielding sheet significantly reduces capacitive interference, ensuring stable operation of the sensor unit by isolating it from conductive lines and high voltage gradients, enhancing the overall performance of the drive device.
Implementation Method 1
the circuit board is in close proximity to electrically conductive lines that extend through the interior of the housing. During operation of the drive device, such lines can interfere with the function of the sensor unit due to capacitive effects.
Implementation Method 2
the shielding sheet shields the circuit board and the elements arranged or configured on the circuit board, so that interference due to capacitive effects is at least reduced
Data Source
AI summary
A drive device. The drive device includes an electric machine arranged in a housing, a rotor of the electric machine being arranged on a drive shaft for conjoint rotation therewith, the drive shaft being rotatably mounted in the housing, and including a sensor unit that is configured to sense a rotary position of the rotor, the sensor unit being provided with a circuit board having at least one sensor element, and the circuit board being in the form of an annular disk and being arranged coaxially to an axis of rotation of the drive shaft. The circuit board is arranged in the housing, and the drive device includes a shielding sheet which radially surrounds at least some parts of the circuit board.