Continuously Variable Transmission Gear Ratio Rate Control
Solution Overview
Problem
Hydrostatic drive systems in machines with continuously variable transmissions face challenges in balancing quick responsiveness with smooth transitions, leading to jerking or lugging during rapid direction, speed, or torque changes, which reduces efficiency and operator comfort.
Innovation Solution
A method and system for controlling the gear ratio rate of change in a machine with a continuously variable transmission, involving an operator input device, electronic data processing, and a gear ratio rate map to determine and adjust the gear ratio smoothly, ensuring a balance between responsiveness and smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the operator commands the hydrostatic drive system to accelerate, decelerate, or change directions quickly, then the responsiveness of the system is improved, but the smoothness of transitions deteriorates causing the machine to jerk or lug
Solution Approach 1:
The patent applies dynamics by making the gear ratio adjustment speed variable rather than fixed. The control system dynamically adjusts the rate of gear ratio change based on real-time operating conditions (current gear ratio, desired gear ratio, machine speed, load conditions) to optimize both responsiveness and smoothness. This is achieved through continuous monitoring and adaptive control of the adjustment speed parameter.
Solution Approach 2:
The patent changes the parameter of adjustment speed from a constant value to a variable parameter that adapts to different operating conditions. By modifying the adjustment speed parameter based on current gear ratio, desired gear ratio, and machine operating state, the system achieves optimal balance between quick responsiveness and smooth transitions across various working conditions.
2Loss of time
If the gear ratio changes too rapidly, then the operator's command responsiveness is improved, but operator comfort and load stability deteriorate
Solution Approach 1:
The control system dynamically determines the optimal adjustment speed based on real-time feedback about machine operating conditions, current gear ratio, and desired gear ratio. This dynamic adaptation allows the system to respond quickly when conditions permit and slow down when necessary to maintain comfort and load stability.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the current gear ratio, comparing it with the desired gear ratio, and using this information along with machine operating conditions to adjust the gear ratio change rate. This closed-loop control ensures that adjustments are made at appropriate speeds to avoid discomfort and load spilling while maintaining responsiveness.
Data Source
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AI summary
A method for controlling a gear ratio rate of change in a machine (10) having a continuously variable transmission (14) includes moving an operator input device (30) to a changed position, receiving electronic data indicative of the changed position, and determining a non-limited desired gear ratio (104) based on the changed position. A maximum gear ratio rate of change (102) corresponding to the non-limited desired gear ratio (104) and an actual gear ratio (106) of the continuously variable transmission (14) is selected from an electronically stored gear ratio rate map (100). A current desired gear ratio is determined based on a previous desired gear ratio and the maximum gear ratio rate of change (102). A commanded gear ratio of the continuously variable transmission (14) is changed to the current desired gear ratio using electronic signals.