Vehicle Suspension Damper Gain Control for Step Impact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control systems for adjustable damping force dampers in vehicle suspension systems fail to uniformly enhance ride performance when a vehicle goes over steps, leading to uncomfortable passenger experiences due to differing feelings between ascending and descending motions.
Innovation Solution
A control system that uses a sprung speed sensor to detect the vehicle's speed over steps and adjusts the damping force gain based on the sign and absolute value of the sprung speed, setting a larger gain for positive sprung speeds to increase damping force when going up and a smaller gain for negative sprung speeds when coming down, thereby altering the damping force to improve ride comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a uniform gain is used for skyhook control in both ascending and descending situations, then the control system is simple, but the passenger may feel uncomfortable and ride performance deteriorates
Solution Approach 1:
The gain is made dynamically adjustable based on the sign of sprung speed. When sprung speed is positive (vehicle going up steps), a larger gain is applied. When sprung speed is negative (vehicle coming down from steps), a smaller gain is applied. This dynamic adjustment resolves the contradiction by adapting the control parameter to different operational conditions.
Solution Approach 2:
The control system changes the gain parameter based on the sign of sprung speed detected by the sensor. This parameter change allows the system to optimize ride performance for different motion directions (ascending vs. descending steps) while maintaining a relatively simple control structure.
2Reliability
If the damping force is increased when the vehicle comes down from steps, then the ride performance should be improved, but the passenger's uncomfortable feeling is not resolved
Solution Approach 1:
Instead of increasing damping force when the vehicle comes down from steps (conventional approach), the invention applies a smaller gain when sprung speed is negative, effectively reducing the damping force adjustment. This inverted approach resolves the contradiction by recognizing that excessive damping during descent causes passenger discomfort.
Solution Approach 2:
The gain parameter is changed based on the sign of sprung speed, allowing the system to apply different damping control strategies for ascending and descending motions. This parameter adaptation resolves the contradiction between ride performance and passenger comfort during descent.
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
This approach effectively reduces passenger discomfort by enhancing ride performance by adjusting the damping force in response to the vehicle's motion over steps, ensuring a smoother ride by managing the damping force differently for ascending and descending motions.
Implementation Method 1
a sprung speed sensor for detecting speed of an upper member of the spring, the sprung speed is generated when the vehicle gets over steps on a road surface
Implementation Method 2
MRF (Magneto-Rheological Fluids), whose viscosity is changed by applying a magnetic field, is employed as a viscous fluid of the adjustable damping force damper
Data Source
AI summary
A control system for a adjustable damping force damper includes a damper and a spring provided on a suspension apparatus of a vehicle, a sprung speed sensor for detecting speed of an upper member of the spring, the sprung speed is generated when the vehicle gets over steps on a road surface and a control unit for setting a gain so as to determine an damping force of the damper based on a product of the sprung speed and the gain. When an absolute value of the sprung speed exceeds a predetermined value, the control unit changes the gain in response to a positive sign or a negative sign of the sprung speed.