Parking Brake Spindle Unloading via Hydraulic Support Pressure
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Solution Overview
Problem
Automatic parking brake systems face issues with spindle flexing and increased frictional forces during release, leading to potential jamming and component stress due to high longitudinal forces when hydraulic pressure is reduced after service brake actuation.
Innovation Solution
A method involving determining driver-applied hydraulic pre-pressures and building up hydraulic support pressure in the brake caliper chamber to unload the spindle, using an ESP modulator, if the pre-pressure exceeds a predetermined threshold, thereby counteracting elastic deformation and ensuring reliable release without component stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the driver applies high hydraulic pre-pressure during service brake actuation, then the braking force is sufficient, but the spindle experiences high longitudinal forces causing elastic deformation and increased frictional forces during release
Solution Approach 1:
The control device performs preliminary action by detecting the driver brake application and pre-charging the hydraulic accumulator with hydraulic fluid before the parking brake release is initiated. This ensures that when release is commanded, hydraulic pressure is already available in the chamber to prevent spindle binding, eliminating the need for the spindle to overcome high frictional forces during release.
2Ease of operation
If hydraulic pressure is reduced after service brake actuation with parking brake engaged, then the parking brake is released, but the spindle is exposed to high longitudinal forces causing flexing and potential jamming
Solution Approach 1:
The hydraulic accumulator serves as a cushioning element that stores hydraulic pressure in advance. During parking brake release, this pre-stored pressure cushions the spindle against high longitudinal forces by maintaining pressure in the hydraulic chamber, preventing elastic deformation and reducing frictional forces between spindle threads before the pressure reduction occurs.
3Loss of energy
If no hydraulic pre-pressure is applied during parking brake actuation, then the hydraulic system is less stressed, but the spindle experiences binding due to increased frictional forces during release
Solution Approach 1:
The system applies partial hydraulic pressure through the accumulator only when needed for parking brake release, rather than maintaining continuous high pressure. The accumulator provides just enough pre-charged pressure to prevent spindle binding during release, avoiding excessive hydraulic energy consumption while ensuring reliable operation.
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 method ensures reliable and stress-free release of the parking brake by adaptively providing hydraulic support pressure based on pre-pressure differences, minimizing spindle deformation and preventing jamming, thus ensuring trouble-free operation.
Implementation Method 1
building up a hydraulic support pressure in the chamber (23) in order to unload the spindle (4), if the first driver-applied pre-pressure is above the pressure threshold value
Implementation Method 2
as a large spring force acts on the spindle via a spring element and a corresponding auxiliary piston
Data Source
AI summary
A method for releasing a brake device for an automatic parking brake, a corresponding device, and a control device enable safely releasing the parking brake without stress on components. A method for actuating a parking brake with a brake device having a brake caliper housing with a chamber configured to receive a fluid, a brake piston, a spindle and a spindle nut, includes determining a first hydraulic driver-applied pre-pressure in the chamber during a mechanical application process of the parking brake. The method further includes comparing the first driver-applied pre-pressure to a predetermined pressure threshold value via the control device; and building up a hydraulic support pressure in the chamber in order to unload the spindle when the first driver-applied pre-pressure is above the pressure threshold value.