Two-Stage Vehicle Suspension Ride Height Control
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Solution Overview
Problem
Vehicle suspension systems take too long to lower to a safe height at the end of a journey, causing safety and comfort issues for passengers exiting, as air suspension systems typically take several seconds to evacuate and lower, leading to an unpredictable vehicle height during egress.
Innovation Solution
A two-stage ride-height adjustment system that detects preliminary and decisive end-of-journey events, with an initial lowering before door opening and a second adjustment upon door opening to reach a predetermined access height, using an electronic processor and memory device to control the suspension system, allowing for a controlled and timely lowering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the suspension system is lowered quickly to reach access height at end of journey, then passenger safety and comfort during egress is improved, but the suspension system may not have enough time to complete the lowering before passenger exits
Solution Approach 1:
The system detects preliminary end-of-journey events (such as ignition switch-off or seat belt unbuckling) and initiates the first stage of suspension lowering in advance. This preliminary action allows the suspension to begin descending before the passenger actually opens the door, ensuring that the vehicle reaches or approaches the access height by the time egress begins, thereby eliminating the safety risk of unpredictable height changes during exit.
Solution Approach 2:
The suspension lowering process is divided into two distinct stages: a first stage that operates in response to preliminary EOJ events and a second stage that operates in response to decisive EOJ events (such as door opening). This segmentation allows the system to manage the lowering process more effectively, providing an initial reduction in height early and completing the adjustment later, thus ensuring safety throughout the egress process.
2Ease of operation
If the suspension system is lowered to access height before door opening, then egress facilitation is improved, but the vehicle may be too low if the journey continues
Solution Approach 1:
The system dynamically adjusts the suspension height based on detected events. It transitions from a normal ride height to an access ride height in response to end-of-journey events, and can reverse this adjustment if the journey continues. This dynamic behavior allows the system to optimize for egress facilitation when needed while maintaining adaptability for continued driving, resolving the contradiction between fixed height optimization and flexible adaptability.
Solution Approach 2:
The system continuously monitors for EOJ events and adjusts suspension height accordingly. If a decisive EOJ event occurs (such as door opening), the system confirms the lowering action; if no such event occurs within a predetermined time, the system can reverse the lowering and return to normal height. This feedback mechanism ensures that the suspension height adapts to the actual driver intent, facilitating egress when the journey ends while maintaining normal operation if the journey continues.
3Device complexity
If the suspension system uses a single-stage lowering response to EOJ event, then system complexity is reduced, but the precision of height control during egress is insufficient
Solution Approach 1:
The control system is segmented into two distinct control stages with different trigger conditions and objectives. The first stage responds to preliminary EOJ events with an initial lowering action, while the second stage responds to decisive EOJ events with a completion or reversal action. This segmentation provides precise height control at different phases of the egress process without requiring overly complex control logic, as each stage has a clear, simple trigger and objective.
Solution Approach 2:
The system implements a preliminary detection and response stage that prepares the suspension for the actual egress event. By detecting preliminary EOJ events and initiating the first stage of lowering in advance, the system achieves better overall height control precision without requiring complex real-time adjustments during the actual door opening moment, thereby balancing control precision with system simplicity.
Data Source
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Figure 3
Figure 3
AI summary
A ride-height adjustment system (100) for a vehicle (10) comprises its suspension system, which is adjustable to change the ride height of a vehicle in which it is fitted. The system has a first means, to detect a preliminary end-of-journey (EOJ) event, such as seat belt unbuckling or ignition switch-off. A controller adjusts the suspension system in a first movement in response to detection of said preliminary EOJ event, to change the ride height of the vehicle towards an access ride height of the vehicle. The access ride height is a predetermined ride height that facilitates egress from and entrance to the vehicle. Second means detect opening of a door of the vehicle. When the ride height of the vehicle remains different from the access ride height after said first movement, the controller is adapted to further adjust the suspension system in a second movement in response to said door-opening detection. This further changes the ride height of the vehicle towards said access ride height of the vehicle.