Brake Valve Travel and Pressure Sensor Signal Processing
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Solution Overview
Problem
Existing methods for indicating driver braking demand in heavy vehicles, such as plunger travel and valve delivery pressure, face challenges including high sensitivity at higher braking demands and lack of initial intent information during pedal movement, requiring additional mechanical components and lacking precision.
Innovation Solution
A driver braking demand indicator apparatus comprising a brake valve with a movable member, travel sensors, pressure sensors, and a controller that processes signals to provide a robust braking demand signal, varying based on plunger travel or delivery pressure thresholds, to accurately reflect the driver's braking intent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plunger travel method is used to indicate driver braking demand, then the method is simple to implement, but sensitivity increases significantly at higher braking demand levels making it difficult to determine driver intent
Solution Approach 1:
The patent segments the braking demand indication into two distinct measurement phases: plunger travel measurement for initial pedal movement (low braking demand) and delivery pressure measurement for sustained braking (high braking demand). This segmentation allows each measurement method to operate in its optimal range, resolving the contradiction between simplicity and precision.
Solution Approach 2:
The system dynamically switches between two measurement methods based on the current operating condition. The controller monitors plunger travel and automatically transitions from travel-based indication to pressure-based indication when braking demand exceeds a threshold, allowing the system to adapt its measurement approach to maintain accuracy across all braking scenarios.
2Measurement precision
If valve delivery pressure method is used to indicate driver braking demand, then accuracy is improved, but information about driver intent is lost during initial stages of pedal movement
Solution Approach 1:
The system performs preliminary measurement using plunger travel during the initial stage of pedal movement, before delivery pressure becomes available. This preliminary action captures the driver's initial braking intent, which would otherwise be lost, and then transitions to pressure measurement once sufficient pressure is established.
Solution Approach 2:
The system ensures continuous and accurate braking demand indication by seamlessly transitioning between two measurement methods. The plunger travel measurement provides continuous indication during initial movement, and the system maintains continuous indication by switching to pressure measurement when that becomes the more accurate metric, eliminating gaps in information.
3Measurement precision
If additional mechanical components are added to improve measurement accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing plunger and delivery pressure system multi-functional by using plunger travel as both a mechanical actuator and an initial measurement parameter. This universality allows the system to extract braking demand information from components already present in the braking system, avoiding the need for additional dedicated measurement mechanisms.
Solution Approach 2:
The system replaces complex mechanical measurement mechanisms with electronic sensors and a controller that processes signals from existing components. The travel sensor and pressure sensor convert mechanical movements and pressures into electrical signals, which the controller then processes to determine braking demand, substituting simple electronic measurement for complex mechanical measurement systems.
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 apparatus provides a precise and robust driver braking demand signal, maintaining accuracy even as vehicle components wear, and reduces the need for additional mechanical components, enhancing the sensitivity and accuracy of braking demand indication.
Implementation Method 1
a travel sensor arranged to (i) sense movement of the brake valve member of the brake valve, and (ii) provide a first signal indicative of the extent of travel of the brake valve member
Implementation Method 2
a delivery pressure line sensor arranged to (i) sense pressure in the delivery pressure line of the brake valve, and (ii) provide a second signal indicative of the pressure in the delivery pressure line
Implementation Method 3
a controller arranged to process the first and second signals to provide a driver braking demand signal for the at least one external device
Data Source
AI summary
A driver braking demand indicator apparatus comprises a brake valve including (i) a brake valve member movable in response to a driver moving a brake applicator member, and (ii) a delivery pressure line to operate a vehicle service brake circuit. The apparatus also comprises a travel sensor arranged to (i) sense movement of the brake valve member, and (ii) provide a first signal indicative of the extent of travel of the brake valve member when movement of the brake valve member is sensed. The apparatus further comprises a delivery pressure line sensor arranged to (i) sense pressure in the delivery pressure line of the brake valve, and (ii) provide a second signal indicative of the pressure in the delivery pressure line. The apparatus also comprises a controller arranged to process the first and second signals to provide a driver braking demand signal for at least one external device.