Work Vehicle Parking Brake Release Calibration From Lever Displacement
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Solution Overview
Problem
Existing work vehicles face issues with inaccurate detection of parking brake release timing due to environmental variations and sensor errors, leading to potential unintended vehicle movement when parked.
Innovation Solution
A work vehicle design that includes left and right operation tools for adjusting rear wheel speeds, a parking brake system with real-time calibration of release displacement calculation, and detection sensors to ensure accurate parking brake release timing, using limit switches and potentiometers to stabilize the disembarkation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the parking brake is automatically operated through displacement of operation tools to a parking position, then the parking brake operation is automated, but the release timing becomes inaccurate due to sensor detection variations and environmental factors
Solution Approach 1:
The system changes the detection parameter from absolute position detection to relative displacement detection. By measuring the displacement distance of the operation tool from the neutral position along the first path, the system achieves accurate release timing detection that is independent of environmental variations and sensor calibration issues.
Solution Approach 2:
The patent replaces mechanical linkage-based parking brake operation with an automated system using detection sensors and control sections. The release displacement calculation section computes the displacement based on sensor signals, and the calibration section adjusts for environmental variations, eliminating the need for direct mechanical connection between the operation tool and brake release mechanism.
2Extent of automation
If the control lever is used to operate the parking brake by displacing to a branch path parking position, then the parking brake is automatically operated, but the vehicle body may become unstable and start moving when the brake is released due to the lever disengaging from the parking position
Solution Approach 1:
The patent separates the parking brake operation function from the travel control function by using independent detection for brake operation (displacement to standby position on third/fourth paths) and brake release (displacement along first/second paths). This segmentation allows the brake to be released while the operation tool remains in a stable neutral position, preventing vehicle instability.
Solution Approach 2:
The system introduces a control section as an intermediary between the operation tool and the parking brake release mechanism. The control section monitors the displacement of the operation tool along the first path and commands the brake release based on calculated release displacement, providing stable and controlled brake release independent of the operation tool's final position.
3Reliability
If a large tolerable range is set for disengagement detection to account for sensor variations, then detection reliability is improved, but the release timing of the parking brake cannot be accurately obtained
Solution Approach 1:
The system changes from detecting disengagement as a binary state (engaged/not engaged) to measuring continuous displacement distance from the neutral position. The release displacement calculation section computes the exact displacement based on sensor signals, and the calibration section adjusts for environmental variations, maintaining both reliability and precision simultaneously.
Solution Approach 2:
The calibration section implements a feedback mechanism that continuously adjusts the detection parameters based on environmental conditions and sensor variations. By calibrating the release displacement calculation in real-time, the system maintains accurate release timing detection despite sensor variations, eliminating the need for large tolerable ranges.
Data Source
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AI summary
A work vehicle includes a left operation tool (12a) that adjusts the speed of a left rear wheel by displacement along a first path, a right operation tool (12b) that adjusts the speed of a right rear wheel by displacement along a second path, a parking brake operating section (71) that operates a parking brake (16) in response to displacement of the left operation tool (12a) along a third path branching from the first path and displacement of the right operation tool (12b) along a fourth path branching from the second path, a parking brake release section (72) that releases operation of the parking brake (16) in response to release displacement of the left operation tool (12a) along the first path from a neutral position or release displacement of the right operation tool (12b) along the second path from a neutral position, a release displacement calculation section (73) that calculates the release displacement, and a calibration section (74) that calibrates the release displacement calculation section (73) in real time.