Wiper Sweep Limit Control Using Tracer Position Feedback
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Solution Overview
Problem
Conventional wiper control systems suffer from inaccuracies in controlling the position of the wiper arm due to environmental changes or soft control failures, leading to under or over sweep, which can cause erratic behavior and potential damage.
Innovation Solution
A system with a tracer connected to the wiper arm that mimics its movement and interacts with position indicators or limit switches to provide precise control, using sensors or limit switches to stop or reverse the wiper arm movement when it approaches predefined limits, independent of motor shaft revolutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional software-coded control logic is used to define motor shaft rotations, then the wiper arm can cover the required sweep arc, but the position control accuracy deteriorates due to under sweep or over sweep from environmental changes or soft control failures
Solution Approach 1:
The patent implements a feedback mechanism using position indicators (sensors) that detect the actual position of the wiper arm and provide this information back to the controller. The controller compares the actual position with the desired position and adjusts the motor shaft rotations accordingly, ensuring accurate positioning even when environmental conditions change or soft control failures occur. This closed-loop feedback system resolves the contradiction by maintaining both reliability and measurement precision.
Solution Approach 2:
The patent replaces the purely software-coded control logic with a hybrid system that incorporates physical position indicators (sensors) and mechanical feedback through the tracer mechanism. This substitution of mechanical sensing elements for software-only control provides tangible, accurate position detection that is independent of environmental conditions, thereby improving position control accuracy while maintaining the required sweep arc coverage.
2Adaptability or versatility
If soft control logic is used to define sweep limits, then the system can operate flexibly, but the system reliability deteriorates due to unexpected failures causing erratic wiper arm behavior
Solution Approach 1:
The patent introduces position indicators (sensors) as intermediary elements between the motor control system and the wiper arm. These sensors act as mediators that provide independent verification of the wiper arm position, preventing erratic behavior caused by soft control failures. The intermediary sensing system maintains system reliability while allowing the soft control logic to retain its flexibility for defining sweep limits and operating modes.
Solution Approach 2:
The patent implements a protective mechanism where position indicators and limit switches are positioned to detect approaching sweep limits before the wiper arm can cause damage or erratic behavior. This beforehand cushioning through proactive position monitoring and early warning systems prevents reliability issues by intercepting potential failures before they manifest as erratic wiper arm behavior, while the flexible soft control logic can still define operational parameters.
3Productivity
If the wiper arm is allowed to sweep beyond predefined positions, then the motor shaft can complete predetermined revolutions, but harmful effects occur due to over sweep or under sweep
Solution Approach 1:
The patent applies preliminary anti-action by positioning limit switches and sensors to detect when the wiper arm is approaching the predefined sweep limits before the motor shaft completes its predetermined revolutions. The system takes preemptive action by stopping or reversing the motor shaft rotation before over sweep or under sweep can occur, thereby preventing harmful effects while still allowing the motor to complete nearly all predetermined revolutions. This ensures productivity is maximized without compromising the wiper arm or windshield.
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
Ensures accurate wiper arm positioning within defined sweep limits, preventing over or under sweep, thereby reducing damage and improving system reliability and accuracy.
Implementation Method 1
Each of the first and second sensors can include respective sensor receivers configured to receive the sensor signal from the tracer to determine a position of the tracer along the sensor array
Data Source
AI summary
A system includes a wiper arm configured to sweep along a sweep zone defined between a start position and an end sweep position, a wiper drive shaft operatively connected at a proximal end to the wiper arm to drive the wiper arm between the start position and the end sweep position, a tracer operatively connected to a distal end of the wiper drive shaft configured to mimic movement of the wiper arm, and one or more position indicators disposed proximate a distal end of the tracer corresponding to at least the start position and the end sweep position, where the distal end of the tracer configured interact with the one or more limiters during operation of the wiper arm.