Work Machine Torque Control via IVT Hydraulic Feedback
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Solution Overview
Problem
Work machines equipped with internal combustion engines and infinitely variable transmissions (IVTs) often experience loss of traction control and wheel slip during low ground speed conditions due to the IVT ratio changes, as the engine torque increase is not effectively communicated to the operator, leading to undesirable wheel spinning.
Innovation Solution
An electronic control system comprising an engine control unit (ECU), transmission control unit (TCU), and pressure transducer, connected via a bus structure, allows for real-time adjustment of torque output from the IVT by limiting input torque from the internal combustion engine based on sensed hydraulic pressure, preventing wheel slip through precise control of fuel rate and IVT ratio adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the IVT ratio changes to match load conditions, then the transmission adapts to varying loads, but the engine torque increase is not effectively communicated to the operator, causing loss of traction control and wheel slip
Solution Approach 1:
The patent implements a feedback mechanism where the controller monitors wheel slip conditions and IVT ratio changes, then adjusts engine torque accordingly. When wheel slip is detected, the controller limits the rate of torque increase from the engine, creating a closed-loop control system that prevents loss of traction control while maintaining adaptability to load conditions.
Solution Approach 2:
The patent dynamically adjusts the torque output characteristics based on operating conditions. The controller modifies the engine torque profile in real-time, limiting torque increase rates during conditions prone to wheel slip while allowing full torque availability during normal operation, making the system adaptive to changing traction requirements.
2Power
If the engine torque is increased to provide more power, then the power output increases, but the operator is not aware of the torque increase, leading to wheel spin out
Solution Approach 1:
The controller provides feedback to the operator about torque increases through the seat cushion actuator, which applies tactile feedback when torque is limited due to wheel slip detection. This gives the operator awareness of torque conditions without requiring visual attention, maintaining ease of operation while preventing wheel spin out.
Solution Approach 2:
The patent introduces an intermediary feedback mechanism (seat cushion actuator) that translates engine torque conditions into tactile signals for the operator. This intermediary provides indirect communication of torque status, allowing the operator to sense torque increases without direct visual or auditory cues, maintaining natural operation while improving awareness.
3Reliability
If a torque limiting mechanism is implemented to prevent wheel slip, then traction control is improved, but the system complexity increases with additional sensors and control logic
Solution Approach 1:
The patent makes the existing IVT controller perform multiple functions: it continues to manage IVT ratio adjustments while also monitoring wheel slip conditions and limiting engine torque when necessary. By integrating these functions into a single controller, the patent improves traction control without proportionally increasing system complexity, as the controller leverages existing sensors and processing capabilities.
Solution Approach 2:
The patent combines the torque limiting function with the existing IVT control system. The controller integrates wheel slip detection, IVT ratio management, and engine torque limitation into a unified control architecture, reducing the need for separate dedicated torque limiting hardware and minimizing overall system complexity while maintaining reliability.
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
This solution ensures stable traction control by accurately limiting torque output from the IVT, preventing wheel slip and enhancing operator control over tractive effort, especially in low ground speed conditions, thereby improving operational safety and efficiency.
Implementation Method 1
a pressure transducer (38) in communication with the hydraulic module (18)
Implementation Method 2
The hydrostatic components convert rotating shaft power to hydraulic flow and vice versa
Implementation Method 3
limiting torque from an output shaft (42) of the IVT (14) based on a sensed pressure
Data Source
Figure 1
Figure 2
AI summary
A work machine (10) includes an internal combustion (IC) engine (12) having an output, and an infinitely variable transmission (IVT) (14) coupled with the IC engine output. The IVT (14) includes a hydraulic module (18) and a mechanical drivetrain module (20). A pressure transducer (38) is associated with and provides an output signal representing a hydraulic pressure within the hydraulic module (18). At least one electrical processing circuit (28) is configured for controlling the IC engine output, dependent upon the output signal from the pressure transducer (38).