Hydraulic Master Cylinder with Nested Piston Segmentation
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Solution Overview
Problem
Existing vehicle brake systems face challenges in seamlessly transitioning between electric motor-assisted braking and traditional hydraulic braking, leading to noticeable changes in braking force that can be imperceptible to the driver, especially in hybrid and electric vehicles where the proportion of braking force from the electric motor can vary constantly.
Innovation Solution
A hydraulic master brake cylinder design featuring two independently displacing push rod pistons, one actuated by muscle power and the other by a brake booster, with hydraulic coupling and a resilient connection, allowing for adjustable amplification factors and energy storage to facilitate smooth transitions and independent operation of both systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single push rod piston is used in traditional brake systems, then the structure is simple, but the transition between electric motor-assisted braking and hydraulic braking is noticeable and imperceptible to the driver
Solution Approach 1:
The single push rod piston is segmented into two independent push rod pistons (first and second) that can move independently relative to each other. This allows separate control of electric motor-assisted braking force and hydraulic braking force, enabling smooth transitions between different braking modes without noticeable changes to the driver.
Solution Approach 2:
One push rod piston is positioned inside the other, creating a nested configuration where the first push rod piston is received by the second push rod piston. This nested arrangement allows independent movement of each piston while maintaining a compact structure, resolving the contradiction between operational smoothness and structural complexity.
2Adaptability or versatility
If the brake booster is designed with high amplification factor for muscle power braking, then braking force is sufficient, but it cannot adapt to varying electric motor braking power in hybrid and electric vehicles
Solution Approach 1:
The brake booster's amplification factor is made dynamically adjustable rather than fixed. The control unit can vary the amplification factor based on the operating mode (electric motor-assisted or muscle power braking) and the required braking force, allowing the system to adapt to different conditions while maintaining reliable and consistent braking performance.
Solution Approach 2:
The amplification factor parameter of the brake booster is changed based on operating conditions. In electric motor-assisted braking mode, a lower amplification factor is used, while in muscle power braking mode, a higher amplification factor is applied. This parameter adjustment enables the system to adapt to varying braking requirements without compromising reliability.
3Extent of automation
If mechanical coupling is used between brake booster and master brake cylinder, then force transmission is direct, but independent control of electric motor-assisted and muscle power braking is limited
Solution Approach 1:
A hydraulic coupling mechanism is introduced between the brake booster and master brake cylinder. This hydraulic system allows independent control of the first and second push rod pistons, enabling separate actuation of electric motor-assisted braking and muscle power braking functions while maintaining a relatively simple overall structure compared to complex mechanical coupling mechanisms.
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
Enables imperceptible transitions between electric motor-assisted and hydraulic braking by allowing independent displacement of push rod pistons, reducing the amplification factor of the brake booster to match the electric motor's braking power, ensuring consistent braking force with muscle power alone, and supporting actuation with a lower power brake booster.
Implementation Method 1
The electric motor of the known brake booster is a hollow shaft motor
Implementation Method 2
a resilient connection, allowing for adjustable amplification factors and energy storage
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a hydraulic main brake cylinder (1), preferably having an electro-mechanical brake booster (7) for a brake assembly of a vehicle. The invention proposes that the main brake cylinder (1) be provided with two pressure rod pistons (2, 3), preferably nesting within each other, one of which is actuated by muscle power, and the other one is actuated by the brake booster (7). Furthermore, an embodiment of the invention provides an energy store (21), which stores energy when the main brake cylinder (1) is released and then transferred to the main brake cylinder (1) upon the actuation thereof, thus supporting the operation of the main brake cylinder (1).