Baler Plunger Positioning and PTO Control
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Solution Overview
Problem
Large square balers require substantial PTO torque to restart, especially when the plunger is initially positioned against a bale, leading to potential stalling of the tractor engine or disengagement of the PTO due to increased load and inertia.
Innovation Solution
A baling system that automatically pre-positions the plunger to a position just past the rear-dead-center position during shut-down and repeatedly activates/deactivates the PTO to accelerate the plunger to a minimum operating speed during restart-up, using a control unit, sensors, and a communication bus to manage the braking and activation intervals based on speed data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plunger is initially positioned against a bale in the forming chamber at restart, then the bale compression function is ready to operate, but the additional load increases PTO torque requirements and can cause tractor engine stalling or PTO disengagement
Solution Approach 1:
The system performs preliminary action by automatically positioning the plunger just past the rear-dead-center position during shut-down, so that when the baler restarts, the plunger is already in the optimal position to contact the bale without creating excessive initial load on the PTO system
Solution Approach 2:
The control unit repeatedly activates and deactivates the PTO during restart-up to accelerate the plunger to minimum operating speed in a controlled manner, preventing excessive torque demands while ensuring the plunger reaches the bale at the appropriate moment
2Power
If the PTO is activated constantly at restart-up, then power is continuously available to the plunger, but the plunger may contact the bale at low speed reducing flywheel momentum and increasing restart torque requirements
Solution Approach 1:
The PTO is activated and deactivated periodically during the restart-up sequence, allowing the flywheel to build momentum during activation intervals while preventing continuous high torque demand. This periodic operation ensures the plunger accelerates to appropriate speed before contacting the bale
Solution Approach 2:
The system dynamically adjusts PTO activation timing based on plunger position and speed feedback from sensors, optimizing the balance between power delivery and plunger acceleration to ensure efficient bale contact
3Force
If automated plunger positioning control is implemented, then restart torque requirements are reduced and engine stalling is minimized, but system complexity increases with additional sensors and control mechanisms
Solution Approach 1:
The control unit receives feedback from the plunger position sensor and PTO speed sensor to automatically adjust PTO activation timing and braking application, eliminating the need for manual intervention while optimizing restart performance and reducing torque requirements
Solution Approach 2:
The system performs self-positioning of the plunger during shut-down and self-acceleration during restart-up through automated control, reducing the need for operator intervention and manual positioning while minimizing restart torque demands
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
Reduces the torque required for restarting the baler, maximizes flywheel momentum, and minimizes the risk of stalling the tractor engine or disengaging the PTO by providing a controlled restart process.
Implementation Method 1
a PTO speed sensor operable to sense a speed of the PTO
Implementation Method 2
a plunger position sensor operable to sense a position of the plunger in the forming chamber
Implementation Method 3
maximizing the flywheel's momentum when the plunger contacts the bale in the forming chamber
Implementation Method 4
Starting a large baler requires substantial PTO torque to overcome the resting inertia of its flywheel
Implementation Method 5
repeatedly apply a braking force to the PTO for a first braking interval and remove the braking force for a second braking interval
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A baling system (10) acts at shut-down to automatically pre-position a plunger (34) so that it is just past a rear-dead-center position when the baler is restarted, thereby minimizing the load on a power take-off (24) during the next restart. In particular, when the power take-off (24) is deactivated, a control unit automatically brakes the power take-off so that the plunger (34) stops in the desired position. Alternatively, the baling system acts at restart-up to automatically repeatedly activate and deactivate the power take-off in order to accelerate the plunger to a predetermined minimum operating speed before activating the power take-off for continuous operation, thereby maximizing a flywheel's momentum during the restart.