Hydraulic Parking Brake Actuation Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic parking brake systems generate annoying background noise due to the operation of electric motor-driven hydraulic pumps, and attempts to mitigate this through vibration decoupling or low engine speed have been insufficient, leading to prolonged pressure build-up times.
Innovation Solution
A method that utilizes a mechanical actuator to increase the volume of hydraulic fluid in the brake chamber, allowing for noise-optimized operation by reducing the service life of the hydraulic actuator and background noise, while the hydraulic actuator builds up clamping force, with the mechanical actuator taking over the holding function more quickly, thus shortening the overall duration of the parking brake process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the hydraulic actuator is used to build up hydraulic pressure in parking brake mode, then the clamping force can be generated, but the pump operation generates annoying background noise and the actuator service life is reduced
Solution Approach 1:
The mechanical actuator is activated before the hydraulic actuator to pre-displace the brake piston and create initial vacuum in the hydraulic chamber. This preliminary mechanical action prepares the system for subsequent hydraulic pressure build-up while minimizing the duration of pump operation, thereby reducing noise and actuator wear.
Solution Approach 2:
The parking brake actuation process is divided into two distinct phases: an initial phase using the mechanical actuator to create vacuum and pre-displace the piston, and a subsequent phase using the hydraulic actuator to build up full clamping force. This segmentation allows each actuator to operate in its optimal range for a limited duration.
2Object-affected harmful factors
If the hydraulic pressure is built up at low engine speed to reduce noise, then the pump operation noises are reduced, but the pressure build-up takes a longer time
Solution Approach 1:
The mechanical actuator creates initial vacuum and pre-displaces the brake piston before hydraulic pressure build-up begins. This preliminary action reduces the volume of hydraulic fluid that needs to be pressurized, thereby shortening the time required for the pump to build up full pressure while operating at low speed.
Solution Approach 2:
The mechanical actuator performs a partial actuation by displacing the brake piston only to the extent needed to create sufficient vacuum and prepare for hydraulic pressure build-up, rather than completing the full stroke. This partial mechanical action reduces the subsequent hydraulic work required and time needed.
3Reliability
If the mechanical actuator is used to increase hydraulic fluid volume in the hydraulic chamber, then the hydraulic actuator service life is extended and noise is reduced, but additional mechanical actuation is required
Solution Approach 1:
The mechanical actuator, which already exists for locking the brake piston in the applied position, is given an additional function: creating vacuum and pre-displacing the piston during the initial phase of parking brake actuation. This multi-functionality eliminates the need for additional components while extending hydraulic actuator life and reducing noise.
Solution Approach 2:
The vacuum creation function and the initial piston displacement function are merged into a single mechanical actuator operation. This combined action prepares the hydraulic system for pressure build-up without requiring separate mechanisms, thereby simplifying the overall system while achieving noise reduction and actuator life extension.
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 the noise associated with hydraulic parking brake operation and shortens the clamping time by approximately 40%, while extending the service life of the hydraulic actuator and maintaining high clamping forces.
Implementation Method 1
During the displacement of the brake piston by means of the mechanical actuator, a negative pressure can arise in the hydraulic chamber, which sucks hydraulic fluid into the hydraulic chamber.
Implementation Method 2
activating the hydraulic actuator when the hydraulic fluid volume in the hydraulic chamber is increased by means of the mechanical actuator in order to build up or increase a clamping force of the parking brake
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a procedure for actuating a parking brake comprising a brake piston that is housed in a hydraulic chamber. Said piston can be displaced within the hydraulic chamber by a hydraulic actuator and a mechanical actuator. During operation of the parking brake, the mechanical actuator is activated in a first step in order to displace the brake piston in the hydraulic chamber in such a way that the volume of a hydraulic fluid contained in the hydraulic chamber increases. At a subsequent time the hydraulic actuator is activated to build up or increase a clamping force of the parking brake. The hydraulically generated or increased clamping force is maintained subsequently by means of the mechanical actuator.