Brake Control Device Preventing Pedal Retraction
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Solution Overview
Problem
The existing brake control systems experience discomfort due to the 'brake pedal retraction phenomenon' when the hydraulic pump starts, causing the brake pedal to move opposite to the driver's intended operation, leading to discomfort and potential vehicle roll-back issues.
Innovation Solution
A brake control device that adjusts the pressure difference using a pressure control valve to synchronize the hydraulic pump's operation with the brake pedal's movement, ensuring the pump starts only when the vehicle transitions from stopped to moving, and maintains a controlled pressure gradient to prevent sudden pedal retraction, thus aligning the pedal movement with the driver's intention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hydraulic pump is started when the vehicle transitions from stopped to moving state during brake pedal operation, then the vehicle can maintain proper braking pressure, but the brake pedal retraction phenomenon occurs causing driver discomfort
Solution Approach 1:
The control device determines whether the brake pedal is being operated before starting the hydraulic pump. By checking the brake pedal operation state in advance (comparing current pedal position with previous position), the system can delay pump startup until the brake pedal operation is complete, preventing the retraction phenomenon while ensuring braking pressure is maintained when needed
2Stress or pressure
If the hydraulic pump starts driving, then sufficient hydraulic pressure is generated for braking, but the temporary decrease in reservoir working fluid causes brake pedal retraction
Solution Approach 1:
The control device continuously monitors the brake pedal position and compares it with the previous position to detect retraction. When retraction is detected during pump startup, the system responds by delaying or adjusting pump operation, creating a feedback loop that prevents the harmful effect while maintaining the necessary hydraulic pressure
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 effectively reduces driver discomfort by ensuring the brake pedal movement aligns with the intended operation, preventing roll-back and minimizing the brake pedal retraction phenomenon, thereby enhancing the braking experience.
Implementation Method 1
a hydraulic pump for generating a pressure difference generation hydraulic pressure for generating a pressure difference (linear-valve pressure difference) to be added to the basic hydraulic pressure
Implementation Method 2
a pressure control valve (normally-open linear solenoid valve) for adjusting the pressure difference by using the pressure difference generation hydraulic pressure
Implementation Method 3
a friction brake mechanism for applying, to a wheel cylinder, a wheel-cylinder hydraulic pressure obtained by adding the pressure difference to the basic hydraulic pressure to generate a friction braking force
Data Source
AI summary
In the brake control device, a wheel-cylinder hydraulic pressure (Pw) obtained by adding the linear-valve pressure difference to a master-cylinder hydraulic pressure (Pm) is applied to the wheel cylinder while the vehicle is running. When an operation of a brake pedal is started while the vehicle is running (t1), the driving of the hydraulic pump is started. Thereafter, when the vehicle is stopped (t2), the driving of the hydraulic pump is stopped. When the start of movement of the vehicle is detected during an operation of returning the brake pedal (t4) and an operation of re-depressing the brake pedal is detected (t5) in this state (specifically, while the vehicle is in a stopped state, the hydraulic pump is in a stopped state, and the brake pedal is being operated), the driving of the hydraulic pump is started (t5).