Brake Pressure Control via Cage Clearance Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Brake pressure control systems face inaccuracies due to variations in cage clearance and pressure versus volume relationships, leading to significant errors in pressure estimation and braking performance.
Innovation Solution
A method that includes a cage clearance reduction phase followed by a wheel control phase, utilizing pressure command strategies to minimize cage clearance dynamics and reduce errors, thereby achieving refined pressure control without the need for pressure transducers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure control is implemented using a pressure sensor to measure actual pressure, then pressure control accuracy can be achieved, but the system complexity and cost increase due to requiring pressure transducers
Solution Approach 1:
The patent replaces the mechanical pressure sensing system (pressure transducers) with an electronic control system that estimates pressure based on pump commands and system modeling. The controller uses a model of the brake system's pressure-volume characteristics to calculate expected pressure without physical sensors, thereby eliminating the need for pressure transducers while maintaining control accuracy.
Solution Approach 2:
The system uses its own control commands and internal models to determine pressure state, rather than relying on external sensing devices. The controller monitors its own pump commands and uses the known characteristics of the brake system to infer the actual pressure, making the system self-diagnosing and self-measuring without additional hardware.
2Adaptability or versatility
If cage clearance variations are present in the brake system, then the pressure versus volume relationship changes, but this leads to significant errors in pressure estimation and control
Solution Approach 1:
The patent implements a cage clearance reduction phase before the wheel control phase. During this preliminary phase, the system applies pressure commands specifically designed to reduce cage clearance to a minimal level. By establishing a known, reduced cage clearance state beforehand, the system eliminates the uncertainty that would otherwise cause estimation errors during the subsequent control phase.
Solution Approach 2:
The system dynamically adjusts the brake pressure in two distinct phases: first reducing cage clearance through controlled pressure application, then maintaining that reduced clearance state during wheel control. This dynamic approach adapts the system's mechanical state to optimize control accuracy, rather than attempting to compensate for fixed, variable clearance through software alone.
3Ease of manufacture
If the brake controller uses empirical testing and modeling to determine pressure control estimates, then pressure control can be achieved, but the mean pressure estimate error remains high (26.5% to 267%)
Solution Approach 1:
The patent introduces a preliminary cage clearance reduction phase that must be executed before the empirical pressure control model can achieve accurate results. By pre-conditioning the mechanical system to have minimal cage clearance, the subsequent empirical modeling and control operations operate from a known, optimized starting point, dramatically reducing the estimation errors that would otherwise occur.
Data Source
AI summary
A method for brake pressure apply in a hydraulic brake system includes commanding a cage clearance reduction phase and commanding a wheel control phase subsequent to the cage clearance reduction phase. Accordingly, the cage clearance is reduced prior to entering the wheel control phase. A method for cage clearance reduction in a hydraulic brake system for roll stability control is also provided.