Pedal Simulator Nonlinear Feedback via Segmented Pistons
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Solution Overview
Problem
Conventional pedal simulators for active brake systems provide inadequate pedal feeling due to simple primary linear reaction forces, leading to inconsistent braking operations and frequent replacement of consumable components, which can affect vehicle safety.
Innovation Solution
A pedal simulator with a serial structure of first and second reaction pistons, damping members, and a reaction spring, providing a low reaction force in the initial braking section through a first damping member and a high reaction force in the last braking section through a second damping member and reaction spring, to generate nonlinear pedal feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If two springs are used as damping members in the pedal simulator, then a reaction force is provided according to brake pedal force, but the pedal feeling is deteriorated due to simple primary linear reaction force and bump feeling
Solution Approach 1:
The single spring system is segmented into two distinct springs (first spring and second spring) with different characteristics. The first spring provides initial reaction force with softer characteristics, while the second spring engages later to provide additional reaction force. This segmentation allows the system to deliver a more nuanced, nonlinear reaction force curve that mimics natural brake pedal feeling, eliminating the bump sensation caused by single-spring linear response.
Solution Approach 2:
Different regions of the pedal stroke are assigned different spring characteristics. The first spring is optimized for the initial pressing phase with lower stiffness to provide soft initial feeling, while the second spring is designed for the later pressing phase with higher stiffness to provide progressive resistance. This local optimization of spring properties across different operational phases creates a more natural and comfortable pedal experience.
2Force
If the first spring is used to provide reaction force in the initial low pedal force section, then reaction force is provided, but bump feeling is generated and pedal feeling is deteriorated
Solution Approach 1:
The first spring is pre-positioned and pre-loaded to provide cushioning from the very beginning of the pedal stroke. This initial spring is designed with softer characteristics to absorb and dampen the initial impact force, preventing the bump sensation that would otherwise occur when the piston first engages the spring system. The second spring is then engaged progressively to maintain smooth force delivery throughout the remaining stroke.
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
Enhances pedal feeling by providing a soft initial braking sensation and a high, smoothly increasing reaction force in the last braking section, reducing the likelihood of sudden or insufficient braking and extending component lifespan.
Implementation Method 1
a first damping member installed at the first reaction piston to be moved together with the first reaction piston, a second damping member installed at the damping housing and configured to provide a reaction force by pressing of the second reaction piston
Implementation Method 2
a reaction spring provided between the second reaction piston and the damping housing
Implementation Method 3
a pedal simulator for an active brake system, which is installed at a master cylinder to receive a hydraulic pressure corresponding to a driver's pedal force
Data Source
AI summary
Disclosed herein is a pedal simulator for an active brake system. According to an aspect of the present invention, the a pedal simulator for an active brake system, which is installed at a master cylinder to receive a hydraulic pressure corresponding to a driver's pedal force and to provide pedal feeling to the driver, includes a simulator block having an oil hole connected with the master cylinder at an upper portion thereof and having a bore therein to be in communication with the oil hole, a damping housing coupled to seal a lower end of the bore, a first reaction piston provided in the bore to be slidable by oil introduced from the master cylinder, a second reaction piston slidably provided in the bore and disposed under the first reaction piston to be spaced apart from the first reaction piston in a predetermined distance, a first damping member installed at the first reaction piston to be moved together with the first reaction piston, a second damping member installed at the damping housing and configured to provide a reaction force by pressing of the second reaction piston, and a reaction spring provided between the second reaction piston and the damping housing.