PTO Torque Limiting Drive Transmission for Agricultural Machines
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Solution Overview
Problem
Existing agricultural machine drive assemblies struggle to smoothly set and maintain desired or maximum torque at the power take-off shaft, regardless of attachment type or manufacturer, leading to potential overloading and inefficient material handling.
Innovation Solution
A self-propelled agricultural machine with a driving engine, PTO output shaft, and drive transmission, equipped with an electronic control unit, sensor, and actuator that measures torque and adjusts the transmission ratio to maintain a target torque value, allowing operators to input desired torque settings, thereby regulating propulsion speed and reducing load on attachments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the maximum torque value is exceeded, the speed of the internal combustion engine is automatically reduced, then the torque at the PTO output shaft is limited, but the power take-off shaft and traveling gear are driven with less speed, causing congestion in the attachment
Solution Approach 1:
The patent applies dynamics by making the transmission ratio variable rather than fixed. The actuator dynamically adjusts the transmission ratio of the drive transmission based on real-time torque measurements, allowing the system to adapt to changing load conditions while maintaining optimal operating parameters for both torque limitation and material flow.
Solution Approach 2:
The patent changes the transmission ratio parameter dynamically to resolve the contradiction. By adjusting the transmission ratio between the drive transmission and PTO output shaft, the system can limit torque at the PTO shaft while independently controlling the speed of the power take-off shaft to maintain material flow rate, thus changing key operating parameters to satisfy both requirements.
2Adaptability or versatility
If the transmission ratio of the drive transmission is fixed, then the structure is simple, but the torque at the PTO output shaft cannot be smoothly set and maintained for different attachment types
Solution Approach 1:
The patent achieves universality by creating a control system that can accommodate different attachment types through a single standardized interface. The electronic control unit receives target torque values applicable to various attachments and automatically adjusts the transmission ratio accordingly, making the system universally adaptable without requiring attachment-specific control mechanisms.
Solution Approach 2:
The patent implements feedback by continuously measuring the actual torque at the PTO output shaft using a torque sensor and comparing it with the target torque value. The electronic control unit uses this feedback information to dynamically adjust the transmission ratio via the actuator, ensuring the actual torque matches the desired target torque for any attachment type.
3Reliability
If the speed of the power take-off shaft is reduced to limit torque, then the torque at the PTO output shaft is controlled, but the quantity of material picked up per distance covered remains the same, leading to congestion
Solution Approach 1:
The patent segments the control functions by separating the control of PTO shaft speed from the control of material flow rate. The transmission ratio adjustment independently controls torque, while the PTO shaft speed can be separately optimized to maintain material flow, dividing the control tasks to resolve the contradiction between torque limitation and ease of material flow management.
Data Source
AI summary
A drive assembly for an agricultural machine. A power take off (PTO) output shaft is connected to a driving motor for driving an attachment. A drive transmission is positioned between and interconnects the driving motor and the support wheels of the agricultural machine. An input device is connected to an electronic control unit. A sensor senses the torque transferred between an attachment and the PTO output shaft, and an actuator is configured to change the transmission ratio of the drive transmission, thereby setting the propulsion speed of the agricultural machine such that the torque transferred between the PTO output shaft and an attachment does not exceed a pre-determined value. The electronic control unit further receives data from the input device and calculates a pre-determined value based on the data received, and thereafter controls the actuator accordingly.