Steering Device Equal Wire Length Impedance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing steering devices face challenges in accurately detecting a driver's grip on the steering wheel due to noise resistance issues and increased complexity and cost associated with the number of sensors and wiring, particularly with electrostatic capacitive sensors installed in the steering core.
Innovation Solution
A steering device with left and right sensors installed in the rim, a detection circuit that maintains equal wire lengths for both sensors to ensure constant impedance, and an electroconductive film interposed between sensors and the substrate to shield electrostatic capacitance and prevent thermal shrinkage, allowing for reliable and accurate detection without a complicated circuit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sensors is increased to improve detection accuracy of the grip portion, then the detection accuracy is improved, but the number of wires increases which disadvantagesly increases the size of the steering wheel and the working time for wiring
Solution Approach 1:
The steering wheel is divided into multiple detection zones with sensors strategically positioned at key grip locations. This segmentation allows accurate detection of driver grip status while using a limited number of sensors, avoiding the need for excessive wiring that would result from using more sensors.
2Device complexity
If electrostatic capacitive sensors are installed in the steering core to simplify structure and reduce wires, then the structure is simplified, but it is necessary to measure a minute change of the electrostatic capacitance which has weak noise resistance
Solution Approach 1:
A shield layer is introduced as an intermediary component between the electrostatic capacitive sensors and the surrounding environment. This shield layer acts as a mediator that blocks external electromagnetic interference and noise from reaching the sensors, thereby protecting the weak electrostatic capacitance measurements while maintaining the simplified structure.
3Reliability
If a shield layer is added to improve noise resistance, then the noise resistance is improved, but the number of parts increases and the manufacturing complexity increases
Solution Approach 1:
The shield layer is merged with the existing steering core structure rather than being added as a separate component. The shield layer is integrated into the steering core during the manufacturing process, combining the structural support function with the electromagnetic shielding function, thereby improving noise resistance without significantly increasing the number of parts or manufacturing complexity.
4Measurement precision
If the wire length of left harness and right harness are made equal to set constant impedance, then the impedance is constant and detection accuracy is improved, but the wiring complexity increases
Solution Approach 1:
The wiring layout is designed with asymmetric routing paths that compensate for differences in sensor positions. By carefully planning the wire routes along the steering core, the left and right harnesses achieve equal lengths despite the asymmetric positions of the sensors, maintaining constant impedance without requiring complex adjustment mechanisms.
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
Enables reliable and accurate detection of a driver's grip on the steering wheel, reducing manufacturing costs and facilitating maintenance while maintaining high detection accuracy and aesthetic integrity.
Implementation Method 1
an electrostatic capacitive sensor which has a flexible plate having flexibility and a plurality of electrostatic capacitance detection sensors provided on the flexible plate
Implementation Method 2
an electroconductive film interposed between sensors and the substrate to shield electrostatic capacitance and prevent thermal shrinkage
Data Source
AI summary
A steering device 10 mounted on a vehicle includes: a steering body 12 having left and right sensors 22L and 22R installed in a rim 16 gripped by a driver to detect a driver's condition; and a detection circuit 14 configured to detect a driver's condition on the basis of a detection signal from at least the left and right sensors 22L and 22R, wherein a wire length Ll of a left harness 30L from the detection circuit 14 to the left sensor 22L is substantially equal to a wire length Lr of a right harness 30R from the detection circuit 14 to the right sensor 22R.