Brake Control Apparatus Pseudo Mode for Actuator Failure
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Solution Overview
Problem
Vehicle stability control cannot be executed when the brake actuator is unavailable, leading to potential safety degradation.
Innovation Solution
A brake control apparatus that includes a master cylinder, a master pressure changing device, and a control unit, which allows for vehicle stability control to be executed in a pseudo mode even when the conventional normal mode using the brake actuator is unavailable, by changing the brake pressure of a target wheel irrespective of the brake pedal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the brake actuator is used for vehicle stability control, then the control precision is improved, but the system reliability deteriorates when the brake actuator becomes unavailable
Solution Approach 1:
The patent changes the control parameter from individual wheel brake pressure (via brake actuator) to master cylinder pressure (via master pressure changing device). This parameter change enables a different control approach that maintains vehicle stability functionality even when the brake actuator is unavailable, thus resolving the reliability issue while accepting a trade-off in control precision
Solution Approach 2:
The patent segments the vehicle stability control into two independent control paths: normal mode using the brake actuator for precise individual wheel control, and pseudo mode using the master pressure changing device for alternative control. This segmentation allows the system to switch between modes based on availability, improving overall reliability
2Reliability
If the pump in the brake actuator is inoperative, then the normal mode becomes unavailable, but the system lacks an alternative control method
Solution Approach 1:
The patent prepares an alternative control path (pseudo mode via master pressure changing device) in advance, so that when the pump fails and normal mode becomes unavailable, the system can immediately switch to the pre-prepared alternative without loss of vehicle stability control capability
Solution Approach 2:
The patent implements dynamic mode switching between normal mode and pseudo mode based on the operational status of the brake actuator pump. This dynamic adaptation allows the control method to flexibly respond to component failures, enhancing both reliability and versatility
3Measurement precision
If the brake actuator is used for individual wheel pressure control, then the vehicle stability control precision is improved, but the system complexity increases
Solution Approach 1:
The patent extracts the essential function of vehicle stability control (controlling brake pressure to stabilize vehicle behavior) from the complex brake actuator system and implements it through the simpler master pressure changing device in pseudo mode, reducing system complexity while maintaining core functionality
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 increases the opportunity and period for vehicle stability control, thereby improving safety, even when the pump in the brake actuator is inoperative, and prevents wheel locking and spinning.
Implementation Method 1
a master cylinder that outputs a brake fluid at a master pressure; a master pressure changing device that is configured to change the master pressure irrespective of an operation of a brake pedal
Implementation Method 2
a brake actuator that is configured to supply the brake fluid output from the master cylinder to a wheel cylinder of each of wheels and to control a brake pressure of the brake fluid supplied to the wheel cylinder
Implementation Method 3
The pump may be configured to cause the brake fluid to return from the reservoir to the input node
Implementation Method 4
a brake actuator that is configured to supply the brake fluid output from the master cylinder to a wheel cylinder of each of wheels and to control a brake pressure of the brake fluid supplied to the wheel cylinder
Data Source
AI summary
A brake control apparatus includes: a master cylinder that outputs a brake fluid at a master pressure; a master pressure changing device that is configured to change the master pressure irrespective of an operation of a brake pedal; a brake actuator; and a control unit that executes vehicle stability control by changing a brake pressure of a target wheel. Modes of the vehicle stability control include a normal mode and a pseudo mode. In the pseudo mode, the control unit operates the master pressure changing device such that the master pressure obtains a target value of the brake pressure of the target wheel, and changes the brake pressure of the target wheel in an interlocking manner with the master pressure. When the normal mode is unavailable, the control unit executes the vehicle stability control in the pseudo mode.