Compounding Gearbox Shift Control for Hydraulic Drive Efficiency
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Solution Overview
Problem
The challenge in travel drives with two hydraulic motors and a summation gear is determining when to switch between driving ranges to minimize power losses and maximize efficiency, as existing solutions rely on manual or speed-dependent controls, which are not optimal.
Innovation Solution
A torque-based control system that switches between driving ranges based on calculated efficiency, using mathematical descriptions of volume flow and torque losses to determine the optimal range for minimal losses and highest efficiency, with a control unit managing clutches to adjust the driving range dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If speed-dependent control is used to switch between driving ranges, then the control logic is simple, but the efficiency is not optimized
Solution Approach 1:
The patent changes the control parameter from simple speed threshold to comprehensive efficiency calculation based on multiple parameters (speed, torque, pump displacement, motor displacement). This allows optimal switching between driving ranges by evaluating actual efficiency rather than following fixed speed thresholds, thereby reducing power loss while managing complexity through systematic parameter integration.
2Ease of manufacture
If manual control is used to switch between driving ranges, then the system is simple to implement, but the efficiency cannot be continuously optimized
Solution Approach 1:
The control system automatically determines the optimal driving range by calculating efficiency based on current operating parameters without requiring manual intervention. The system serves itself by continuously monitoring speed, torque, pump displacement, and motor displacement to autonomously select the most efficient operating mode, thereby reducing power loss while maintaining implementation feasibility through automated decision-making.
3Force
If both hydraulic motors are active in all driving ranges, then the displacement volume is sufficient for high forces, but mechanical power loss increases
Solution Approach 1:
The patent segments the operation into two distinct driving ranges: first driving range where both hydraulic motors are active to provide high forces through large displacement volume, and second driving range where only one hydraulic motor is active to reduce mechanical power loss at higher speeds. This segmentation allows the system to optimize force output when needed while minimizing energy loss during high-speed operation.
4Speed
If the pump operates at maximum volume flow, then high speeds are achieved, but the swivel angle limit is reached reducing efficiency
Solution Approach 1:
The patent dynamically adjusts the system configuration by switching from one hydraulic motor active to the other hydraulic motor active as speed increases. This dynamic reconfiguration allows the active motor to operate with higher swivel angles and better hydraulic efficiency even when the pump operates at maximum volume flow, thereby maintaining energy efficiency across the full speed range.
Data Source
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AI summary
The invention described here relates to a switching strategy for a drive system with two hydraulic motors and a summing gearbox (ZMSG). With this strategy, the switch between the at least two possible driving ranges or operating states occurs as soon as the other driving range, or one of the other driving ranges, promises a better efficiency in power transmission than the current driving range. The strategy is used in conjunction with torque-based control of the drive system.