Park Slow Release Controller for Smooth Vehicle Stopping
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Solution Overview
Problem
Modern vehicle brake systems experience abrupt stopping and unsettling movement when shifting into a park state due to the engagement of the parking sprag, causing undesirable jerking motions and unexpected vehicle movement.
Innovation Solution
A controller monitors brake fluid pressure and transmission states, maintaining a predetermined pressure below the threshold to prevent movement while allowing the vehicle to roll with resistance when shifting into park, thereby reducing speed and smoothing the stopping process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the parking sprag is engaged to prevent rotation of the transmission output shaft, then the vehicle is prevented from moving, but the vehicle comes to an abrupt stop causing jerking motion and user discomfort
Solution Approach 1:
The controller applies brake pressure before the parking sprag engages with the internal gear, maintaining the sprag in a pre-loaded state that reduces冲击 during engagement. This preliminary braking action smooths the transition into park state by preventing sudden jerking motion when the sprag drops into the gear recess.
Solution Approach 2:
The brake system provides cushioning force before the parking sprag engagement occurs. By maintaining predetermined brake pressure during the transition, the system cushions the abrupt stopping that would otherwise occur when the sprag engages, reducing the jerking motion and improving user comfort.
2Reliability
If full brake pressure is applied to prevent vehicle movement, then the vehicle is securely held, but the stopping process becomes abrupt and causes jerking motion
Solution Approach 1:
The brake pressure is dynamically adjusted during the parking transition rather than applied statically. The controller maintains a predetermined pressure below the threshold required to fully prevent movement, allowing the vehicle to roll with resistance until the parking sprag engages, then transitions to full braking. This dynamic pressure adjustment smooths the stopping process.
Solution Approach 2:
The brake pressure parameter is changed during the parking operation. The controller maintains pressure below the threshold pressure required to prevent movement during the transition phase, then allows full braking after sprag engagement. This parameter change enables both smooth transition and secure holding.
3Productivity
If the transmission shifts directly into park state, then the parking sprag engages quickly, but the vehicle moves slightly before stopping causing an unsettled feeling
Solution Approach 1:
The brake pressure is maintained continuously during the entire parking transition process rather than being applied only after the sprag engages. This continuous braking action prevents the vehicle from moving freely during the transition, eliminating the unsettled feeling while maintaining quick engagement through the predetermined pressure level.
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 reduces the abruptness of the stopping motion and improves user experience by allowing the vehicle to roll with controlled resistance, minimizing jerking and providing a smoother transition into park state.
Implementation Method 1
A brake system for a vehicle may selectively prevent movement of the vehicle when brake fluid of the brake system is at or above a threshold pressure
Data Source
AI summary
A controller is provided and may monitor a pressure of brake fluid and a state of a transmission of a vehicle. The controller may maintain predetermined brake pressure below a threshold pressure required to prevent movement of the vehicle in response to movement of the transmission into a park state and in response to a drop in brake pressure below the threshold pressure to permit the vehicle to roll with resistance for a predetermined time following the drop of brake pressure below the threshold pressure.