Work Vehicle Hill Start Control Using Clutch and Parking Brake
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Solution Overview
Problem
Existing hill start assistance systems for work vehicles are complex and expensive, requiring sophisticated components and often relying on unnecessary vehicle modifications to prevent rollback on slopes.
Innovation Solution
A driving assistance system that automatically engages and disengages the clutch and parking brake based on vehicle speed and slope, using existing components like the service brake, parking brake, and a controller to prevent rollback without additional complexity or cost, by activating the parking brake on steep slopes and deactivating it after the clutch is reengaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hill start assistance systems use sophisticated components to detect vehicle unintended motion, then reliability of preventing rollback is improved, but device complexity increases
Solution Approach 1:
The system uses the existing service brake actuation signal to trigger clutch disengagement and parking brake activation, making the system self-sufficient without requiring additional sensors or complex detection mechanisms. The controller monitors the service brake signal and automatically manages the clutch and parking brake based on this input.
Solution Approach 2:
The existing service brake system and controller are made to serve multiple functions: not only decelerating the vehicle but also triggering the hill start assistance sequence by disengaging the clutch and activating the parking brake. This eliminates the need for dedicated hill start detection components.
2Measurement precision
If hill start assistance systems use sophisticated components and additional sensors, then measurement precision of slope and vehicle motion is improved, but device complexity and cost increase
Solution Approach 1:
The system repurposes existing vehicle components (service brake actuator, clutch controller, parking brake actuator) to perform the hill start assistance function, eliminating the need for additional slope sensors or motion detection devices. The existing controller processes the service brake signal to infer the need for hill start assistance.
Solution Approach 2:
The existing controller is programmed to handle multiple functions: monitoring service brake actuation, controlling clutch disengagement, and activating the parking brake. This multi-functionality approach avoids adding dedicated detection and control components for hill start assistance.
3Reliability
If the system automatically activates the parking brake on slopes, then reliability of preventing rollback is improved, but ease of operation may be reduced due to automatic intervention
Solution Approach 1:
The system proactively activates the parking brake before the driver needs it, based on detection of service brake actuation and calculated slope. This preliminary action prevents rollback automatically, removing the burden from the driver to manually apply the parking brake on slopes.
Solution Approach 2:
The controller continuously monitors service brake actuation and slope conditions, and automatically adjusts the parking brake state accordingly. This feedback loop ensures the parking brake is activated only when needed (on slopes when service brake is applied), maintaining simplicity while ensuring reliability.
Data Source
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AI summary
A driving assistance system for a work vehicle (10), comprising a controller configured to: - disengage the clutch when the work vehicle speed is less than a speed threshold and the service brake is actuated, whereby the work vehicle is brought to a stop; - obtain a slope value representative of the slope of a surface on which the work vehicle has stopped; - automatically activate the parking brake when the clutch has been disengaged and the slope value is greater than a slope threshold; - reengage the clutch when the service brake is released, while maintaining the parking brake activated; - automatically deactivate the parking brake when a predetermined delay after release of the service brake has elapsed, the predetermined delay being greater than the time required to reengage the clutch, or when reengagement of the clutch has reached a predetermined value.