Brake Control Device Mode Switching for Pedal Feel
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Solution Overview
Problem
The existing brake control systems, particularly in rapid startup scenarios, fail to provide a good brake operation feeling due to the maintenance of the simulator cutoff valve in a closed state during mode switching from depression force fluid pressure mode to normal control mode, leading to an uncomfortable brake pedal operation for the driver.
Innovation Solution
A brake control device that includes a rapid startup mode switching control mechanism, which switches the braking mode from depression force fluid pressure mode to normal control mode during the returning operation of the brake pedal, and a target breaking force calculation mechanism to adjust the brake pedal operation quantity, ensuring a smooth transition and improved brake operation feeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the simulator cutoff valve is maintained in a closed state during mode switching from depression force fluid pressure mode to normal control mode, then the brake pedal operation feeling becomes firm and uncomfortable, but the mode switching stability is improved
Solution Approach 1:
The simulator cutoff valve state is dynamically changed based on the brake pedal operation phase. During rapid startup, the valve is opened during the returning operation of the brake pedal rather than maintaining a fixed closed state, allowing the system to adapt to different operational phases and provide comfortable brake pedal feeling while ensuring stable mode switching.
Solution Approach 2:
The simulator cutoff valve is opened in advance during the returning operation of the brake pedal before the mode switching is completed. This preliminary action prepares the fluid pressure control circuit for normal control mode, enabling smooth transition and comfortable brake pedal operation feeling without compromising mode switching stability.
2Ease of operation
If the braking mode is switched from depression force fluid pressure mode to normal control mode during the returning operation of the brake pedal, then the brake operation feeling is improved, but the control system complexity increases
Solution Approach 1:
The brake control device utilizes the natural returning operation of the brake pedal as a trigger for mode switching. The system automatically detects the returning operation phase and switches from depression force fluid pressure mode to normal control mode without requiring additional complex control mechanisms, achieving improved brake operation feeling while minimizing control system complexity.
3Ease of operation
If the simulator cutoff valve is opened during rapid startup, then the brake operation feeling becomes comfortable, but the fluid pressure control stability deteriorates
Solution Approach 1:
The simulator cutoff valve is opened preliminarily during the returning operation of the brake pedal before normal control mode is fully established. This timing ensures that the fluid pressure control circuit is prepared for normal control while the brake pedal is naturally returning, providing comfortable operation feeling without compromising fluid pressure control stability.
Solution Approach 2:
The system monitors the brake pedal operation state to determine when to open the simulator cutoff valve. By using feedback from the brake pedal returning operation as a trigger, the system ensures that the valve is opened at the appropriate moment when fluid pressure control stability can be maintained while achieving comfortable brake operation feeling.
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
The solution enhances the brake operation feeling during rapid startup by allowing the brake control device to switch modes appropriately, reducing the discomfort felt by the driver and ensuring a consistent braking force, while also enabling immediate braking force generation when needed.
Implementation Method 1
a power fluid pressure generator (30) to pressurize fluid regardless of the operation of the brake pedal
Implementation Method 2
a stroke simulator (70) which generates an anti-power depending on an operation quantity of the brake pedal operation and permits the brake pedal operation
Implementation Method 3
a fluid pressure control circuit (LC) which regulates fluid pressure of fluid pressurized by the power fluid pressure generator and transmits fluid pressure to a plurality of wheel cylinders
Implementation Method 4
a depression force fluid pressure circuit (LR, LF) which transmits the fluid pressure of fluid pressurized by pedal force input into a brake pedal (10) to a plurality of wheel cylinders
Data Source
AI summary
When a brake ECU is started up rapidly by a brake pedal operation, the brake ECU executes a depression force fluid pressure mode. When the control pressure detected by a control pressure sensor becomes smaller than a switching determination threshold value, the brake ECU determines that an operation of returning a brake pedal is being performed, and switches the braking mode from the depression force fluid pressure mode to a normal control mode. Accordingly, even when the operation of a stroke simulator has been started, no uncomfortable feeling is given to a driver. Further, even when the operation of returning the brake pedal is not being performed, the braking mode is switched from the depression force fluid pressure mode to a simulator non-operation control fluid pressure mode when a vehicle starts to travel. Consequently, desired braking force can be rapidly generated.