Air Spring Hold Control for Unnecessary Stiffness Switching
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Solution Overview
Problem
Active suspension systems with variable stiffness springs experience repeated switching between high and low stiffness states due to discontinuous vehicle acceleration, leading to mechanical wear, computational inefficiency, and uncomfortable driving experiences during dynamic conditions.
Innovation Solution
A control system that determines a spring state hold condition based on the rate of change of acceleration, sending a hold control signal to maintain high stiffness during dynamic driving conditions, and adjusts stiffness states based on adjusted acceleration thresholds considering the rate of change of acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the air spring stiffness is switched based on acceleration threshold values, then the suspension adapts to road conditions, but repeated switching during dynamic driving causes mechanical wear and uncomfortable driving experience
Solution Approach 1:
The control system performs preliminary evaluation by assessing the rate of change of acceleration (jerk) before triggering a stiffness switch. This preliminary action prevents premature or unnecessary switching during dynamic maneuvers, reducing mechanical wear while maintaining necessary adaptability.
Solution Approach 2:
The patent introduces jerk (rate of change of acceleration) as an intermediary parameter between the primary acceleration signal and the stiffness switching decision. This intermediary provides additional context about the driving dynamics, allowing the system to distinguish between genuine road conditions requiring adaptation and transient effects causing unnecessary switching.
2Speed
If the control system continuously monitors acceleration to manage spring operation, then the suspension responds to road conditions, but processing large quantities of acceleration data increases computational load
Solution Approach 1:
The control system extracts only the essential features from the acceleration data - specifically the rate of change of acceleration (jerk) - rather than processing the entire acceleration signal. This extraction approach maintains responsive control while significantly reducing computational requirements by focusing on the most relevant parameter.
Solution Approach 2:
Instead of continuously processing all acceleration data points, the system applies partial monitoring by evaluating specific derived parameters (jerk) only when needed for switching decisions. This partial action approach provides sufficient information for effective control without the excessive computational burden of full signal processing.
3Productivity
If the air spring switches stiffness state frequently to track acceleration changes, then the suspension maintains optimal performance, but mechanical components experience accelerated wear and tear
Solution Approach 1:
The system uses feedback from the jerk signal to regulate switching frequency. By monitoring the rate of change of acceleration, the system receives feedback about driving dynamics that prevents unnecessary switching during transient conditions, thereby extending component service life while maintaining performance when truly needed.
Solution Approach 2:
The control system performs preliminary assessment of driving conditions through jerk evaluation before executing stiffness switches. This preliminary action filters out transient acceleration variations that would otherwise trigger unnecessary switching, reducing mechanical wear while preserving suspension performance for genuine road condition changes.
Data Source
AI summary
Aspects relate to control systems for an air spring of a suspension system of a vehicle. The control system is configured to, when the air spring is operating in a high stiffness state during vehicle motion, receive a signal indicative of a rate of change of acceleration of the vehicle. The control system is configured to determine if a spring state hold condition is satisfied in dependence on the rate of change of acceleration. If the spring state hold condition is determined to be satisfied, the control system is configured to output a hold control signal to cause the air spring to remain operating in the high stiffness state.