Electric Hydraulic Brake Redundancy With Low-Pulsation Pump Layout
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Solution Overview
Problem
Existing electric hydraulic brakes face challenges in space constraints due to dual brake systems, noise generation from piston pumps, and the need for redundancy in brake system control to prevent malfunction.
Innovation Solution
The electric hydraulic brake incorporates a dual controller design with an auxiliary actuator featuring an odd number of piston pumps and a hydraulic circuit that includes separate front and rear wheel circuits, allowing for redundancy and reduced noise through improved structural design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 2-box type brake system is configured to provide redundancy, then system reliability is improved, but installation space requirements increase and physical space constraints in the engine room are violated
Solution Approach 1:
The patent merges the dual controller functionality into a single integrated controller unit that can operate in both normal and redundant modes. The controller includes first and second control units integrated into one device, allowing it to perform the functions of both controllers in a 2-box system while occupying only one installation space, thus resolving the contradiction between reliability and space requirements.
2Reliability
If two piston pumps are used in the auxiliary actuator, then redundancy is provided, but noise and pulsation increase due to pump characteristics
Solution Approach 1:
The patent applies local quality by making the piston pumps asymmetric in their operational characteristics. Specifically, the first and second piston pumps have different displacement amounts, allowing them to operate at different phases and frequencies. This local differentiation in pump characteristics enables redundancy while reducing overall noise and pulsation through destructive interference of pressure waves.
Solution Approach 2:
The patent employs asymmetry by designing the piston pumps with unequal displacement volumes. The first piston pump has a different displacement amount than the second piston pump, creating asymmetric operation that prevents synchronized pulsation. This asymmetric design allows the pumps to compensate for each other's pressure fluctuations, reducing noise while maintaining redundant functionality.
3Reliability
If additional controllers and piping are added for redundancy, then system reliability improves, but device complexity and space requirements increase
Solution Approach 1:
The patent applies universality by designing a single controller that performs multiple functions - it can operate as a primary controller during normal conditions and switch to redundant controller operation when needed. The integrated controller includes both first and second control units that can function independently or together, eliminating the need for separate dedicated redundant controllers and their associated piping, thus reducing complexity while maintaining reliability.
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 enhances system reliability, reduces noise and pulsation, and maintains braking functionality even with controller malfunctions, ensuring vehicle stability and control.
Implementation Method 1
a pump unit having three or more piston pumps linked with the second motor, and configured to transmit the hydraulic pressure to the plurality of wheel brakes
Implementation Method 2
a plurality of solenoid valves; a first controller configured to control the first motor and the hydraulic circuit
Data Source
AI summary
An electric hydraulic brake includes a plurality of wheel brakes; a reservoir storing brake oil; a master cylinder connected to the reservoir and configured to generate hydraulic pressure with a first motor; an auxiliary actuator including a second motor and a pump unit having piston pumps linked therewith that transmits the hydraulic pressure to the wheel brakes when the master cylinder malfunctions; a hydraulic circuit that selectively transmits the hydraulic pressure to the wheel brakes, and including a front wheel hydraulic circuit and rear wheel hydraulic circuit each configured to transmit the hydraulic pressure to a pair of front wheel brakes and a pair of rear wheel brakes, respectively, and a plurality of solenoid valves; a first controller to control the first motor and the hydraulic circuit with braking input; and a second controller to control the first motor and the front wheel hydraulic circuit when the first controller malfunctions.