Infinitely Variable Transmission Control for Smooth Work Machine Deceleration
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Solution Overview
Problem
Work machines equipped with infinitely variable transmissions (IVTs) experience abrupt deceleration when the ground speed control pedal is fully released, leading to undesirable stopping, as the IVT ratio increases, causing the vehicle inertia to back-drive the engine and abruptly slow down the vehicle.
Innovation Solution
The integration of a brake actuator with a sensor system and electrical processing circuits that adjust the IVT input/output ratio to prevent back-driving of the engine, allowing for controlled deceleration and engagement of service brakes, enabling smoother slowing and stopping of the work machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the IVT ratio is increased when the ground speed control pedal is released, then the vehicle inertia back-drives the engine and the vehicle stops quickly, but the deceleration becomes abrupt and undesirable to the operator
Solution Approach 1:
The patent applies dynamics by making the IVT ratio adjustable and variable rather than fixed. The control system dynamically modifies the IVT ratio based on operating conditions (engine braking request signal) to achieve smooth deceleration. The ratio is increased in a controlled manner over time rather than abruptly, allowing the vehicle to decelerate smoothly while still utilizing engine braking effect.
Solution Approach 2:
The patent implements feedback through the control system that monitors engine braking request signals and adjusts the IVT ratio accordingly. The system receives feedback about the desired braking state and continuously modifies the transmission ratio to achieve the target deceleration profile, preventing abrupt stopping while maintaining control.
2Use of energy by moving object
If the IVT ratio is increased to allow engine back-driving, then engine braking is achieved, but service brake wear increases due to abrupt deceleration
Solution Approach 1:
The system dynamically adjusts the IVT ratio to optimize the balance between engine braking and service brake usage. By controlling the rate and extent of ratio increase, the system maximizes engine braking effectiveness while preventing conditions that would cause abrupt deceleration and excessive service brake wear.
Solution Approach 2:
The patent ensures continuous useful action by maintaining engine braking throughout the deceleration process through continuous IVT ratio adjustment. This continuous engine braking action reduces the need for intermittent service brake application, thereby extending service brake lifespan while maintaining effective deceleration control.
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 allows for controlled deceleration and stopping of work machines without abrupt slowing, improving operator experience and reducing wear on service brakes by utilizing engine braking and adjusting the IVT ratio to maintain net torque transfer, thus enhancing operational efficiency and safety.
Implementation Method 1
the IVT ratio of input to output speed increases as the speed control pedal is released and the vehicle inertia back drives the engine and abruptly slows down the vehicle
Implementation Method 2
at least one service brake, wherein said brake sensor provides a second output signal indicating a further actuation of said brake actuator
Data Source
Figure 1
Figure 2
AI summary
A work machine (10) includes an IC engine (12) having an output, an IVT (24) having an input coupled with the IC engine output, and a ground speed actuator (32). A desired speed sensor (34) associated with the ground speed actuator (32) provides an output signal indicating a slower ground speed. At least one electrical processing circuit is configured for increasing an input/output (I/O) ratio of the IVT (14), dependent upon the sensor output signal, such that a net torque transfer back-driven from the IVT input to the IC engine output is substantially zero.