Rear Suspension Leaf Spring Roll Stiffness
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Solution Overview
Problem
Conventional rear suspension systems for vehicles, particularly in small or medium-size buses and trucks, face challenges in maintaining riding quality and driving stability due to the inverse relationship between natural frequency and spring constant, which deteriorates when the vehicle is partially loaded, as the spring constant is optimized only for empty or fully loaded states.
Innovation Solution
The proposed solution involves a rear suspension apparatus using longitudinal main leaf springs, longitudinal helper leaf springs, and a transverse helper leaf spring applied to the rear axle, with stopper mechanisms to adjust spring constant values (K1, K2, K3) based on load states, and a multi-plate transverse helper leaf spring to enhance roll stiffness and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large spring constant (K) value is used to support vehicle weight, then durability is improved, but natural frequency increases and riding quality deteriorates
Solution Approach 1:
The suspension system is divided into multiple independent leaf springs (main leaf spring, first helper leaf spring, second helper leaf spring) instead of using a single spring. Each spring can independently contribute to weight support and can be optimized for specific functions, allowing the system to achieve both high durability and good riding quality through distributed spring constants.
Solution Approach 2:
The second helper leaf spring is arranged in the width direction (transverse dimension) of the vehicle, perpendicular to the longitudinal arrangement of the main and first helper leaf springs. This spatial arrangement allows the second helper spring to primarily resist roll movements while the other springs handle vertical load support, adding a dimensional aspect to the suspension functionality.
2Force
If the spring constant is optimized for empty or fully loaded states, then weight support is improved, but riding quality deteriorates in half-full loaded state
Solution Approach 1:
The suspension system dynamically adapts its effective spring constant based on the load state through the interaction of multiple leaf springs with different stiffness characteristics. As the vehicle transitions between empty, half-full, and fully loaded states, different combinations of springs engage and disengage, automatically adjusting the overall spring constant to optimize both weight support and riding quality for each loading condition.
Solution Approach 2:
The system changes its effective spring constant parameter according to the load state by utilizing multiple leaf springs with different stiffness values. The main leaf spring provides baseline support, while the helper leaf springs with different constants are progressively engaged as load increases, effectively changing the system's spring constant to match the actual loading conditions and maintain optimal riding quality.
3Force
If longitudinal main leaf springs and longitudinal helper leaf springs are used, then vertical load support is improved, but roll stiffness is insufficient
Solution Approach 1:
The second helper leaf spring is arranged in the width direction (transverse dimension) of the vehicle, perpendicular to the longitudinal arrangement of the main and first helper leaf springs. This spatial arrangement allows the second helper spring to primarily resist roll movements while the other springs handle vertical load support, adding a dimensional aspect to the suspension functionality.
Solution Approach 2:
The second helper leaf spring serves multiple functions: it provides additional vertical load support capability while simultaneously being the primary component for resisting roll movements. This multi-functionality allows a single component to address both weight support and roll stability requirements, improving overall system efficiency.
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 configuration effectively supports the vehicle's weight across varying load states, improves riding quality by optimizing spring constant values, and increases roll stiffness, thereby enhancing driving stability, especially in the half-full loaded state where natural frequency issues are most pronounced.
Implementation Method 1
functions of such springs of the vehicle are to absorb shocks generated from the road surface and to support a weight of the vehicle
Implementation Method 2
The first and second stopper mechanisms are in contact with the transverse helper leaf spring when the vehicle body frame moves downwardly or rolls to restrict a movement of the vehicle body frame
Data Source
AI summary
A rear suspension apparatus of a vehicle includes: a transverse helper leaf spring connected to a rear axle and disposed in a transverse direction; and a first stopper mechanism and a second stopper mechanism contacting the transverse helper leaf spring when the vehicle moves. The rear suspension apparatus is capable of improving riding quality by using a new spring constant value generated by the transverse helper leaf spring when freight is loaded and a vehicle body frame moves downwardly, and restricting rolling movement of the vehicle when rolling is caused, thereby increasing roll stiffness and improving driving stability.