Brake Hold Control Using Electric-Hydraulic Force Sharing
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Solution Overview
Problem
Existing brake hold functions in vehicles consume excessive power due to continuous energization of differential pressure control valves and additional power consumption from independent electric brake force generation, especially when using the Electric Parking Brake (EPB) method.
Innovation Solution
A brake control device that combines hydraulic and electric braking systems, where the electric braking device drives a propulsion shaft to contact a piston, allowing the differential pressure control valve to generate only the required hydraulic braking force for non-electric braking wheels by subtracting the electric braking force from the target braking force, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the differential pressure control valve is continuously energized to maintain hydraulic pressure in the brake hold function, then the brake hold function is reliably maintained, but power consumption is increased
Solution Approach 1:
The differential pressure control valve is energized only temporarily during brake pedal operation to establish hydraulic pressure, then de-energized while maintaining the brake hold function through the stored hydraulic pressure in the closed circuit, converting continuous energization to periodic action
Solution Approach 2:
Hydraulic pressure is established in advance during brake pedal operation before the brake hold function is needed, allowing the system to maintain the stationary state without continuous energization of the control valve
2Reliability
If the electric parking brake generates electric braking force independently to maintain stationary state, then the brake hold function is achieved, but extra braking force is generated causing additional power consumption
Solution Approach 1:
The electric parking brake mechanism is integrated with the hydraulic braking system, allowing the same braking member to receive force from either hydraulic pressure or electric motor, eliminating the need for independent electric brake force generation
Solution Approach 2:
The electric motor of the electric parking brake replaces the hydraulic pressure source temporarily during brake pedal operation, driving the propulsion shaft to directly press the braking member against the braked member without requiring hydraulic pressure from the differential pressure control valve
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 enables the brake hold function to be realized with low power consumption by minimizing the energization of differential pressure control valves and eliminating extra power consumption from independent electric brake force generation, while maintaining the stationary state efficiently.
Implementation Method 1
an electric braking device that makes the braking member press against the braked member by driving a motor so that an electric braking force applied to an electric braking wheel
Implementation Method 2
a hydraulic braking device that makes a braking member press against a braked member rotating integrally with wheels by using hydraulic pressure so that hydraulic braking force applied to the front and rear wheels
Implementation Method 3
the differential pressure control valve connected to the non-electric braking wheel different from the electric braking wheel
Data Source
AI summary
A brake control device according to an embodiment executes, for an electric braking wheel of either the front wheel and the rear wheel, a brake hold control for driving an electric braking device to move a propulsion shaft toward the braked member to be braked and bring it into contact with a piston, calculating a target braking force for maintaining the stationary state of the vehicle, subtracting a first braking force from the target braking force to calculate a required hydraulic braking force applied to the non-electric braking wheel different from the electric braking wheel, and controlling a differential pressure control valve connected to the non-electric braking wheel of the hydraulic braking device so that the required hydraulic braking force is applied to the non-electric braking wheel.