Vehicle Braking Force Control Device with Dual Current Limits
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Solution Overview
Problem
Conventional vehicle braking force control devices consume excessive power when shifting to a backup power source, leading to increased capacity requirements and higher costs due to unnecessary power consumption after the shift.
Innovation Solution
The device employs two current limit values: a first current limit value for ensuring increased braking hydraulic pressure and a second, lower current limit value for maintaining necessary minimum braking pressure, allowing for reduced power consumption and capacity of the backup power source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single current limit value is used after transitioning to the auxiliary power source, then the braking hydraulic pressure can be increased to ensure minimum braking force, but needless power consumption occurs due to insufficient limiting
Solution Approach 1:
The current limit value is made dynamic rather than static. The control unit switches between a first current limit value (higher) for pressure increase and a second current limit value (lower) for pressure maintenance. This dynamic adjustment allows the system to ensure minimum braking force while reducing needless power consumption after the pressure target is reached.
Solution Approach 2:
The system changes the current limit parameter based on the operational phase. Initially, a higher current limit value is applied to rapidly increase braking hydraulic pressure. Once the necessary minimum pressure is achieved, the parameter is changed to a lower current limit value to maintain pressure with minimal power consumption, thereby resolving the contradiction between reliability and energy use.
2Reliability
If the auxiliary power source capacity is increased to ensure necessary minimum braking force with needless power consumption, then braking reliability is improved, but system cost increases
Solution Approach 1:
By dynamically adjusting the current limit value between two states (higher for pressure increase, lower for maintenance), the system reduces the total energy consumption during backup operation. This allows the auxiliary power source to be sized smaller while still ensuring the necessary minimum braking force, thereby reducing system cost without compromising braking reliability.
3Speed
If the first current limit value is used continuously after transition to auxiliary power source, then pressure-increase responsiveness is ensured, but power consumption is excessive
Solution Approach 1:
The system employs periodic or phased action by switching between two current limit values at appropriate times. The first current limit value is applied initially to ensure rapid pressure increase responsiveness. After the necessary minimum pressure is achieved, the system transitions to the second current limit value to maintain pressure with reduced power consumption, thus resolving the contradiction between speed and energy use.
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 approach ensures the necessary minimum braking force while reducing the capacity and power consumption of the auxiliary power source, allowing the braking system to operate longer on the backup power source with minimized power usage.
Implementation Method 1
an auxiliary power source 14 for outputting current to an electric actuator 24 of a braking device 6 for producing braking hydraulic pressure
Data Source
AI summary
A vehicle braking force control device includes a braking force control unit. The braking force control unit is configured to shift to a drive state so as to use an auxiliary power source when a main power source fails, and to limit current outputted to an electric actuator of a braking device for producing braking hydraulic pressure when a transition is made to the drive state using the auxiliary power source. The braking force control unit has two current limit values used during actuation of the electric actuator by the auxiliary power source, the current limit values being a first current limit value for ensuring increased-braking-hydraulic-pressure characteristics, and a second current limit value for ensuring a necessary minimum braking hydraulic pressure, the second current limit value being less than the first current limit value.