Brake Actuator Unit Simulator Piston Integration
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Solution Overview
Problem
Existing brake actuator units experience deteriorated pedal feeling during regenerative braking due to pressure variations in the master cylinder, which are directly transferred to the brake pedal, and require an additional simulator chamber to improve this feeling, increasing the unit's size.
Innovation Solution
A brake actuator unit design that includes a housing with a master cylinder, operating fluid reservoir, simulator, input shaft, control plunger, and output shafts, utilizing first and second simulator pistons with springs and retainers to provide repulsive force to the pedal, and a return spring between the master cylinder and control plunger, eliminating the need for an additional simulation chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an additional simulator chamber is installed to improve pedal feeling, then the pedal feeling is improved, but the size of the brake actuator unit is increased
Solution Approach 1:
The patent combines the simulator function with the existing master cylinder by integrating simulator pistons into the master cylinder structure. The simulator pistons are positioned within the master cylinder and share the same hydraulic fluid chamber, eliminating the need for a separate simulator chamber while maintaining the pedal feeling improvement function.
Solution Approach 2:
The master cylinder is designed to perform multiple functions: it serves as both the pressure generation chamber for brake actuation and the simulator chamber for pedal feeling. The simulator pistons operate within the same hydraulic system as the main brake pistons, allowing the master cylinder to provide both braking force and simulated pedal resistance without requiring additional dedicated components.
2Adaptability or versatility
If pressure of the master cylinder is changed during regenerative braking operation, then regenerative braking control is achieved, but the pressure variation is directly transferred to the brake pedal, deteriorating the pedal feeling
Solution Approach 1:
The simulator pistons act as intermediaries between the master cylinder pressure changes and the brake pedal. When pressure variations occur in the master cylinder during regenerative braking, the simulator pistons absorb and isolate these variations, preventing direct transmission to the pedal while still allowing the ECU to detect pedal displacement through the input shaft movement.
Solution Approach 2:
The simulator springs are pre-loaded to provide a baseline repulsive force that counteracts pressure variations in the master cylinder. This preliminary counter-force prevents the direct transmission of pressure fluctuations to the pedal, maintaining consistent pedal feeling regardless of the master cylinder pressure state during regenerative braking operations.
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 design enhances brake pedal feeling while reducing the overall size of the brake actuator unit by integrating the simulator functions within the existing components, improving pedal feedback and operational efficiency.
Implementation Method 1
first and second simulator springs applying elastic force to the first and second simulator pistons
Data Source
AI summary
A brake actuator unit capable of improving the pedal feeling. The brake actuator unit includes a housing, a master cylinder connected to one end of the housing and provided therein with first and second pistons arranged in parallel to each other, an operating fluid reservoir coupled to an upper portion of the master cylinder to store operating fluid, a simulator accommodated in the master cylinder to provide repulsive force to a pedal, an input shaft moving back and forth according to an operation of the pedal, a control plunger slidably moving back and forth together with the input shaft, first and second output shafts positioned corresponding to first and second pistons to move back and forth together with the control plunger, and a pedal displacement sensor connected to the input shaft.