Torque Control System for Off-Road Vehicle Transmission Shifting
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Solution Overview
Problem
Large self-propelled agricultural vehicles face challenges in managing engine torque to prevent transmission damage during shifting, as high output engines often exceed the shifting-state clutch ratings of their transmissions, leading to the need for expensive, heavy, and large transmissions to handle these forces.
Innovation Solution
Implementing a torque control system that allows the engine to operate at two power levels: one below the shifting-state clutch rating during shifts and another above it when not shifting, with a control system that reduces engine torque during shifts to match the transmission's shifting-state rating, ensuring the transmission is protected while maintaining sufficient power for operational systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high output engines are used to meet increased power requirements of larger self-propelled applicators, then engine power output is improved, but transmission clutch ratings are exceeded during shifting
Solution Approach 1:
The system dynamically adjusts engine torque output based on transmission state. During shifting operations, the engine control system temporarily reduces torque to remain within clutch ratings, while allowing full torque output during non-shifting operations. This dynamic adaptation resolves the contradiction by making engine power delivery flexible rather than fixed.
Solution Approach 2:
The engine torque parameter is changed based on transmission operating state. The control system monitors transmission shift status and adjusts the engine torque parameter accordingly - reducing it during shifts to protect clutches, and maintaining high values during normal operation to meet power requirements of operational systems.
2Reliability
If control systems always limit engine torque across its entire power band to protect transmission, then transmission reliability is improved, but power availability for operational systems is reduced
Solution Approach 1:
Rather than applying a static torque limit across all operating conditions, the system dynamically adjusts torque limits based on real-time transmission state. The engine can deliver full torque during non-shifting operations to maintain productivity, while automatically reducing torque only during shifting events to protect the transmission.
Solution Approach 2:
The control system anticipates shifting events and proactively adjusts engine torque before the shift occurs. By detecting upcoming shift conditions and reducing torque in advance, the system prevents clutch overload while minimizing impact on operational system power availability, as the torque reduction is temporary and targeted.
3Reliability
If heavy duty transmissions with high clutch ratings are used to match engine power, then transmission durability is improved, but vehicle weight and cost increase
Solution Approach 1:
Instead of selecting a transmission with permanently high clutch ratings to handle all possible torque conditions, the system changes the effective torque parameter through electronic control. This allows the use of a lighter transmission with lower clutch ratings, as the engine torque is electronically limited during shifting to match the transmission's actual capacity.
Solution Approach 2:
The patent replaces mechanical solutions (larger, heavier transmission components) with an electronic control solution. Rather than physically upgrading the transmission to handle high torque, the engine control system electronically manages torque delivery to remain within the transmission's clutch ratings, substituting mechanical oversizing with electronic torque management.
Data Source
AI summary
A self-propelled off-road agricultural vehicle such as a product applicator is provided with a system for torque control at shift points. The self-propelled applicator has a drivetrain configured with two power levels of its engine. One power level limits engine power output to a value at or below a shifting-state clutch rating of the transmission to protect the transmission while shifting. The second power level allows engine power to exceed a shifting-state clutch rating of the transmission when the transmission is not shifting.