Vehicle Holding Function Noise Reduction via Intermediate Pressure Control
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Solution Overview
Problem
Conventional vehicle holding methods using hydraulic braking systems generate undesirable noise due to the overflow of shutoff valves during the execution of the holding function, which can irritate drivers and reduce acceptance of these systems.
Innovation Solution
The method involves building an intermediate pressure between the shutoff valve and the brake pressure buildup device, which is less than the new holding pressure, to prevent audible overflow when the valve is opened, and using existing components like motorized piston-cylinder devices or electromechanical brake boosters to maintain the holding pressure without additional installation or increased manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shutoff valve is opened to replenish holding pressure in the wheel brake cylinder, then the holding pressure is maintained, but audible overflow noise is generated
Solution Approach 1:
The brake pressure buildup device is activated before opening the shutoff valve to pre-build pressure in the actuator. This preliminary action ensures that when the valve opens, there is no significant pressure difference to cause audible overflow, while still enabling the wheel brake cylinder to maintain its holding pressure through controlled fluid transfer.
Solution Approach 2:
The system changes the pressure parameter in the actuator from zero (or low) to an intermediate value before valve opening. By controlling the actuator pressure to be between 0 and the wheel brake cylinder pressure, the patent prevents the conditions that generate audible overflow noise while maintaining the ability to replenish holding pressure when needed.
2Reliability
If the brake pressure buildup device is continuously activated to maintain holding pressure, then the holding function is reliable, but energy consumption increases
Solution Approach 1:
Instead of continuous activation, the brake pressure buildup device is activated periodically only when the holding pressure in the wheel brake cylinder drops below a threshold. This periodic action maintains reliable holding function while significantly reducing energy consumption compared to continuous operation.
Solution Approach 2:
The system uses pressure sensing to automatically determine when activation is needed, making the system self-regulating. The holding pressure maintenance occurs automatically when pressure drops, without requiring continuous external control input or energy expenditure.
3Object-generated harmful factors
If an intermediate pressure is built up in the actuator before opening the shutoff valve, then overflow noise is reduced, but the control complexity increases
Solution Approach 1:
The system uses feedback from pressure sensors to monitor the holding pressure in the wheel brake cylinder and the actuator pressure. This feedback enables the control device to automatically adjust the brake pressure buildup device activation and shutoff valve control to maintain intermediate pressure conditions, reducing overflow noise without requiring complex manual control procedures.
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 significantly reduces noise generation during the holding function, ensuring a quieter operation and increased driver acceptance without requiring additional components or increased installation space, while maintaining effective vehicle hold functionality.
Implementation Method 1
an intermediate pressure, which is less by a factor of between 1.2 and 10 in comparison with the new holding pressure, is built up between the at least one shutoff valve and the at least one brake pressure buildup device with the aid of the at least one brake pressure buildup device
Data Source
AI summary
A control device and method for executing a holding function using a hydraulic braking system of a vehicle including building up an initial holding pressure in at least one wheel brake cylinder using at least one brake pressure buildup device and closing at least one shutoff valve situated between the at least one wheel brake cylinder and the at least one brake pressure buildup device, a new holding pressure being built up in the wheel brake cylinder, in that an intermediate pressure less than the new holding pressure is built up between the shutoff valve and the brake pressure buildup device using the brake pressure buildup device, the shutoff valve is opened upon the presence of the intermediate pressure between the shutoff valve and the brake pressure buildup device, and brake fluid is transferred using the brake pressure buildup device through the open shutoff valve into the wheel brake cylinder.