Infinitely Variable Transmission Clutch Control for Work Machine Traction
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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 at low ground speeds, leading to inefficiencies and reduced fuel efficiency due to significant power loss across torque converters, especially in applications like bucket loading where increased tractive effort is needed without tire spinning.
Innovation Solution
A work machine configuration with an IVT that includes an adjustable module and a mechanical module with a clutch, where an operator input device provides a power limit control signal to an electrical processing circuit, allowing for controlled I/O ratio and clutch pressure adjustments to maintain constant tractive effort and minimize slip, combining the benefits of torque control and infinite speed ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the IVT ratio is adjusted to match load conditions at low ground speeds, then the engine can maintain higher speed and power availability, but the drive wheels lose traction and spin out due to excessive torque
Solution Approach 1:
The patent applies dynamics by making the clutch torque capacity adjustable and variable during operation. The clutch is designed with adjustable friction characteristics that can be modified in real-time based on operating conditions, allowing the system to dynamically adapt between providing high torque capacity when needed and limiting torque to prevent wheel spin when appropriate.
Solution Approach 2:
The patent changes the parameter of clutch friction characteristics from fixed to variable. By adjusting the clutch friction coefficient or torque capacity parameter based on ground speed and load conditions, the system can control the amount of torque transmitted to the drive wheels, preventing excessive torque that causes wheel spin while maintaining power availability from the engine.
2Force
If a torque converter is used to provide torque multiplication, then tractive effort is increased, but significant power is lost due to slip between the converter and transmission
Solution Approach 1:
The patent changes the parameter of clutch slip from uncontrolled to controlled by adjusting the clutch friction characteristics. The clutch is designed to maintain optimal slip conditions that balance torque multiplication needs with minimizing energy loss, allowing the system to operate at peak efficiency across different loading conditions.
Solution Approach 2:
The patent implements feedback control by monitoring the slip speed and torque conditions across the clutch and adjusting the clutch friction characteristics accordingly. This feedback mechanism ensures that the clutch operates in the optimal range for torque transmission while minimizing excessive slip that would cause energy loss.
3Device complexity
If the clutch friction characteristics are fixed, then the design is simpler, but the clutch cannot adapt to varying load conditions and ground speeds
Solution Approach 1:
The patent applies dynamics by transforming the static clutch design into a dynamic one where friction characteristics can change during operation. The clutch incorporates mechanisms such as adjustable friction surfaces or variable friction materials that allow the friction coefficient to be modified based on real-time operating conditions including ground speed, load, and slip rate.
4Force
If the clutch slip speed is high, then torque transmission is maintained, but fuel efficiency deteriorates due to excessive power loss
Solution Approach 1:
The patent changes the clutch friction parameter dynamically to optimize the balance between torque transmission and energy efficiency. By adjusting the friction coefficient based on slip speed measurements, the clutch can maintain adequate torque transmission at lower slip speeds, thereby reducing power loss and improving fuel efficiency without sacrificing tractive capability when needed.
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 configuration effectively prevents traction loss by limiting transmission output torque and speed, maintaining consistent tractive effort, and improving fuel efficiency by minimizing power loss through continuous monitoring and adjustment of clutch slip speed.
Implementation Method 1
A work machine including an IC engine, and an IVT coupled with the IC engine. The IVT includes an adjustable module, and a mechanical module. A clutch is coupled with an output from the mechanical module
Data Source
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AI summary
A work machine (10) includes an internal combustion engine (12), and an infinitely variable transmission (14) coupled with the combustion engine (12). The infinitely variable transmission (14) includes an adjustable module (18) and a mechanical module (20), with an adjustable input/output ratio. A clutch (22) is coupled with the mechanical module (20) and has an output. An adjustable operator input device (40) provides an output signal representing a power limit control. At least one electrical processing circuit (30) is coupled with the operator input device (40) and configured for controlling a selected combination of the input/output ratio and the clutch output, dependent upon the output signal from the operator input device (40).