MFWD Control via Speed Ratio and Brake Status
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Solution Overview
Problem
Mechanical front-wheel drive (MFWD) systems in work vehicles, such as backhoe loaders, face inefficiencies due to unnecessary activation and brake wear when operators manually activate MFWD for traction, leading to reduced vehicle speed and premature brake wear, especially during higher transport speed ratios.
Innovation Solution
An electrical controller unit communicates with the MFWD switch and shifter to automatically deactivate MFWD during higher transport speed ratios and activate it upon brake application, overriding manual requests to optimize speed and brake life by considering the vehicle's speed ratio and brake status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If MFWD is activated during higher transport speed ratios, then traction is improved, but vehicle speed is reduced due to front drive axle windage losses and tire scrubbing
Solution Approach 1:
The system dynamically adjusts MFWD activation status based on real-time operating conditions (speed ratio, brake status, traction requirements). The controller automatically activates or deactivates MFWD clutch engagement depending on whether the vehicle is in working or transport mode, optimizing performance for each condition without manual intervention.
Solution Approach 2:
The system changes the operational parameters of the drivetrain by monitoring speed ratio and brake status. When transport speed ratio is detected and brake is applied, the system changes the engagement state of the MFWD clutch, transitioning from disengaged (high speed) to engaged (braking) state to achieve four-wheel braking.
2Force
If MFWD is manually activated for traction, then additional traction is obtained, but brake wear increases due to unnecessary activation
Solution Approach 1:
The system uses feedback from speed ratio sensors and brake status sensors to automatically control MFWD activation. The controller receives signals about current operating conditions and automatically adjusts MFWD engagement, eliminating the need for manual activation and preventing unnecessary brake wear through intelligent decision-making based on real-time feedback.
Solution Approach 2:
The system performs self-service by automatically managing MFWD activation without operator intervention. The controller monitors vehicle operating conditions and autonomously determines when MFWD should be activated or deactivated, reducing operator-induced brake wear through automated control logic.
3Speed
If MFWD is deactivated during transport speed ratios, then vehicle speed is maximized, but four-wheel braking capability is lost
Solution Approach 1:
The system dynamically switches between two operational states: during normal transport, MFWD remains deactivated for maximum speed; upon brake application detection, MFWD automatically engages to provide four-wheel braking capability. This dynamic state transition resolves the contradiction by adapting to real-time braking requirements.
Solution Approach 2:
The system prepares for potential braking needs by maintaining the capability to quickly engage MFWD when brake application is detected. The automatic activation upon brake application serves as a preemptive measure to ensure four-wheel braking readiness, counteracting the loss of braking capability that would otherwise result from MFWD deactivation during transport.
Data Source
AI summary
A work vehicle includes a mechanical front wheel drive (MFWD) and a controller unit for automatically controlling the MFWD based at least on a MFWD request signal, a speed ratio request signal, and a brake-status signal. The MFWD request is overridden if the speed ratio request is for a predetermined speed ratio (such as fourth gear), and the overriding of the MFWD request is interrupted if the brake-status signal indicates that a brake of the work vehicle is applied.