Tractor PTO Control System for High Inertia Load Startup
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Solution Overview
Problem
Tractor engines stall or activate safety mechanisms when starting high inertia loads like balers due to insufficient torque from the PTO shaft, and existing solutions require modifications to the baler or additional hydraulic systems.
Innovation Solution
A control system connected to the tractor's engine, clutch, and gearbox that performs sequential steps to manage engine speed and transmission ratios, allowing gradual acceleration of the PTO shaft to prevent stalling and overload, without modifying the towed implement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the PTO shaft is directly connected to the baler flywheel, then the baler can be driven, but the tractor engine stalls or the PTO overload protection activates due to insufficient torque during startup
Solution Approach 1:
The startup process is segmented into multiple phases with different transmission ratios. The control system divides the acceleration process into stages: first using a lower transmission ratio to provide high torque for initial acceleration, then switching to a higher transmission ratio for normal operation, preventing engine overload throughout the startup sequence
Solution Approach 2:
The transmission ratio is made dynamic rather than fixed. The control system automatically adjusts the transmission ratio based on the real-time speed of the PTO shaft, selecting appropriate gear combinations during different phases of flywheel acceleration to optimize torque delivery and prevent engine stalling
2Power
If a hydraulic motor is used to supplement torque during baler startup, then the flywheel can be accelerated, but the baler must be modified and a hydraulic system must be added
Solution Approach 1:
The existing change-speed gearbox, originally designed for other functions, is repurposed to provide torque multiplication during baler startup. The control system leverages the existing mechanical components (clutch, gearbox, PTO shaft) to achieve the torque supplementation function, eliminating the need for separate hydraulic motors or complex additional systems
Solution Approach 2:
The tractor's own existing components (engine, clutch, change-speed gearbox) are used to provide the necessary torque multiplication. The system serves itself by utilizing its inherent mechanical advantages rather than requiring external hydraulic systems or modifications to the baler, achieving the function through intelligent control of existing resources
Data Source
Figure 1
Figure 2
AI summary
A tractor comprising a control system (30) to perform the sequential steps of: disengaging the clutch (12) a first time; selecting a first transmission ratio of the change speed gearbox (14); engaging the clutch (12) a first time to drive the PTO shaft (16); determining the speed of the PTO shaft (16); disengaging the clutch (12) a second time when the PTO shaft (16) attains a predetermined first speed; selecting a second transmission ratio of the change speed gearbox (14); and engaging the clutch (12) a second time to drive the PTO shaft (16) up to a desired second speed.