Braking Force Control Apparatus for Vehicle Slip Prevention
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Solution Overview
Problem
Conventional braking force control apparatuses fail to effectively prevent excessive braking slips when a specific abnormality occurs in the downstream braking actuator, where upstream pressure can be supplied but braking pressure cannot be reduced, leading to instability and potential loss of control during excessive driver braking operations.
Innovation Solution
The apparatus includes an upstream braking actuator and a control unit that selects the higher target braking pressures for the front and rear wheels, determines a backup target upstream pressure, and controls the upstream pressure to this level when a specific abnormality occurs in the downstream actuator, ensuring that the braking pressures are managed to prevent excessive slips and maintain vehicle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the downstream braking actuator is used to individually control braking pressures for each wheel, then braking pressure control precision is improved, but when a specific abnormality occurs (upstream pressure can be supplied but braking pressure cannot be reduced), the system loses the ability to prevent excessive braking slips
Solution Approach 1:
The control unit performs preliminary detection of abnormalities in the downstream braking actuator before they lead to excessive braking slips. When an abnormality is detected (specifically when upstream pressure can be supplied but braking pressure cannot be reduced), the control unit proactively switches to backup control mode, adjusting the upstream pressure to prevent the harmful effect from occurring. This preliminary action resolves the contradiction by maintaining reliability while preserving the precision control capability when normal.
Solution Approach 2:
The system establishes a backup control mechanism that acts as a safety cushion against the potential failure mode. When the downstream braking actuator exhibits specific abnormality, the backup control using upstream pressure adjustment provides a protective measure to prevent excessive braking slips. This beforehand cushioning resolves the contradiction by ensuring reliability is maintained even when the precision control system encounters abnormalities.
2Reliability
If anti-skid control is stopped when an abnormality occurs in the downstream braking actuator, then system safety is improved, but the ability to prevent excessive braking slips is lost
Solution Approach 1:
The control system dynamically adapts its operation mode based on the detected abnormality condition. Instead of statically stopping anti-skid control when abnormalities occur, the system transitions to a dynamic backup control mode that adjusts upstream pressure in real-time. This dynamic response resolves the contradiction by maintaining both system safety and braking slip prevention capability, allowing the system to operate effectively in both normal and abnormal conditions.
3Reliability
If the upstream pressure is controlled to a backup target level when specific abnormality occurs, then braking slip prevention is improved, but braking force reduction is achieved
Solution Approach 1:
The control unit changes the pressure parameter from the normal operating level to a backup target level when specific abnormality is detected. By adjusting the upstream pressure to a predetermined backup target pressure that is lower than normal operation pressure, the system prevents excessive braking slips while maintaining sufficient braking force for safe operation. This parameter change resolves the contradiction by optimizing both braking slip prevention and maintaining adequate braking force through intelligent pressure adjustment.
Data Source
AI summary
A braking force control apparatus has an upstream braking actuator for generating an upstream pressure common to four wheels, a downstream braking actuator individually controlling braking pressures supplied to braking force generating devices of the wheels using the upstream pressure, and a control unit. When the downstream braking actuator is abnormal and the upstream pressure can be supplied to the braking force generating devices, but a braking pressure of any one of the wheels cannot be normally reduced, the control unit selects higher one of the target braking pressures of the left and right front wheels and higher one of the left and right rear wheels, determines lower one of the two selected target braking pressures as a backup target upstream pressure, and controls the upstream braking actuator such that the upstream pressure becomes the backup target upstream pressure.