Vehicle Height Control for Gear-Dependent Wheel Longitudinal Force
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Solution Overview
Problem
Existing vehicle suspension systems fail to effectively reduce longitudinal forces on wheels due to vertical inputs from the road surface, particularly when the moment of inertia of the drive system changes with gear ratio fluctuations.
Innovation Solution
A vehicle height control device with a suspension arm and shock absorber arrangement that adjusts vehicle height based on the equivalent moment of inertia of the drive system, using an electronic control unit to control the vehicle height adjustment device to offset changes in longitudinal forces through backward inclination of the wheel's rotational axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the suspension arm is arranged so that the rotational axis draws a backward inclined locus to offset longitudinal force, then longitudinal force reduction is improved, but the effectiveness deteriorates when the equivalent moment of inertia of the drive system changes due to transmission gear ratio changes
Solution Approach 1:
The patent applies the dynamics principle by making the vehicle height adjustable based on the transmission gear ratio. The control unit dynamically changes the vehicle height according to the detected gear ratio, allowing the suspension system to adapt its characteristics. When the gear ratio changes, the vehicle height is adjusted to maintain the optimal backward inclination angle of the rotational axis locus, ensuring continuous effectiveness in offsetting longitudinal forces despite changes in the drive system's equivalent moment of inertia.
Solution Approach 2:
The patent applies the parameter changes principle by modifying the vehicle height parameter in response to gear ratio changes. The control unit detects the gear ratio and accordingly adjusts the vehicle height to a predetermined value, thereby changing the geometric parameters of the suspension system. This parameter adjustment maintains the appropriate backward inclination angle of the rotational axis locus, ensuring the suspension effectively counteracts longitudinal forces across different driving conditions.
2Device complexity
If the vehicle height is fixed, then the structure is simple, but the longitudinal force cannot be effectively reduced when the gear ratio changes
Solution Approach 1:
The patent applies the self-service principle by enabling the vehicle height control system to automatically adjust the vehicle height based on the transmission gear ratio without requiring complex external intervention. The control unit detects the gear ratio and autonomously determines the appropriate vehicle height, making the system self-regulating. This approach balances structural simplicity with effective longitudinal force reduction, as the adjustment mechanism leverages existing sensor and actuator infrastructure.
3Force
If the vehicle height is adjusted to maintain optimal backward inclination angle, then longitudinal force reduction is improved, but the control system complexity increases
Solution Approach 1:
The patent applies the feedback principle by implementing a control unit that detects the transmission gear ratio and uses this information to determine the appropriate vehicle height. The system continuously monitors the gear ratio and adjusts the vehicle height accordingly, creating a closed-loop control mechanism. This feedback-based approach ensures that the vehicle height is optimally adjusted to maintain the backward inclination angle of the rotational axis locus, effectively reducing longitudinal forces while managing control system complexity through intelligent algorithms.
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
Effectively reduces longitudinal forces on the wheel by dynamically adjusting vehicle height to counteract changes in the drive system's moment of inertia, ensuring consistent performance across varying gear ratios.
Implementation Method 1
The suspension arm is arranged so that the rotational axis, when viewed in the lateral direction of the vehicle, draws a locus that is inclined backward as the wheel moves up and down
Implementation Method 2
the electronic control device is configured to control the vehicle height adjustment device such that a change in the angle of backward inclination of the locus necessary to offset a change in the first longitudinal force due to a change in the equivalent moment of inertia by a change in the second longitudinal force is achieved by a change in the vehicle height
Data Source
AI summary
A vehicle height control device applied to a vehicle equipped with a wheel that is rotatably supported about a rotational axis and has a tire, and a drive system that drives the wheel via a transmission by an engine, in which a suspension arm is arranged between a wheel carrier and a vehicle body so that the rotational axis when viewed in the lateral direction of the vehicle draws a locus inclined backward as the wheel moves up and down, the vehicle height control device includes a vehicle height adjustment device and an electronic control device that controls the vehicle height adjustment device, and the electronic control device acquires information on an index indicating an equivalent moment of inertia of the drive system, and controls the vehicle height adjustment device such that the smaller the equivalent moment of inertia indicated by the index, the lower the vehicle height.