Brake Hydraulic Pressure Control for Natural Start
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Solution Overview
Problem
Conventional vehicle brake hydraulic pressure control systems experience a sudden feeling during start from standstill due to the simultaneous increase in drive torque and reduction in braking force, particularly on flat roads, leading to an unnatural acceleration sensation.
Innovation Solution
A vehicle brake hydraulic pressure control apparatus that includes gradient acquiring means to determine the road surface gradient, releasing brake hydraulic pressure completely before drive torque increases only when the gradient is less than a predetermined value, allowing the drive torque to act as a start force without braking force effects, thereby achieving a natural start from standstill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If brake hydraulic pressure is released simultaneously with drive torque increase, then vehicle holding control is released efficiently, but the driver experiences an unnatural sudden acceleration feeling
Solution Approach 1:
The brake hydraulic pressure is released in advance before the drive torque increases. The control device determines that the vehicle is in a halt state, releases the brake hydraulic pressure completely, and then allows the drive torque to increase. This preliminary release of braking force eliminates the simultaneous occurrence of torque increase and braking force reduction, thereby achieving a natural acceleration feeling while maintaining efficient vehicle holding control release.
2Ease of operation
If brake hydraulic pressure is released completely before drive torque increases, then natural acceleration feeling is achieved, but control complexity increases due to timing coordination requirements
Solution Approach 1:
The control device uses feedback from vehicle state detection (halt state determination) to control the timing of brake hydraulic pressure release. By detecting whether the vehicle is in a halt state and coordinating the release timing with drive torque increase timing, the system achieves natural acceleration feeling without requiring complex manual timing coordination, thus reducing perceived control complexity.
3Power
If drive torque is increased before decompression is completed, then power delivery is improved, but the difference between drive torque and braking force abruptly increases causing sudden vehicle movement
Solution Approach 1:
The brake hydraulic pressure is released in advance before the drive torque increases. The control device completes the decompression process first, then allows the drive torque to increase. This preliminary action ensures that the braking force is already reduced when power delivery begins, preventing the abrupt increase in the difference between drive torque and braking force, thereby maintaining vehicle motion stability while preserving power delivery capability.
Data Source
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AI summary
A vehicle brake hydraulic pressure control apparatus (control apparatus 100), installed in a vehicle reducing a drive torque when the vehicle is at a halt, that includes vehicle holding control means 113 for performing vehicle holding control by holding a brake hydraulic pressure when the vehicle is at a halt. The vehicle holding control means 113 is configured to release the holding of the brake hydraulic pressure based on the accelerator operation of a driver when the vehicle is at a halt and, in the releasing of the holding of the brake hydraulic pressure, release the holding of the brake hydraulic pressure completely before the drive torque of the vehicle starts increasing.