Hydrostatic Gearbox Control Unit for Shifting Accuracy
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Solution Overview
Problem
Existing multi-speed transmission systems driven by hydrostatic transmissions often experience undesired shifting operations due to lack of effective control mechanisms, leading to inefficient gear changes.
Innovation Solution
A control unit is designed to determine the currently engaged gear, set speed parameters, and compare actual speed with predefined limits and thresholds, issuing shift commands only when necessary to avoid undesired shifts, with adaptability based on selected driving modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If gear shifting is controlled only by speed comparison with limit values, then gear changes can be automated, but undesired shifting operations occur
Solution Approach 1:
The control unit continuously monitors actual speed parameter values and compares them with minimum and maximum limit values for the current gear. This feedback mechanism ensures that gear shifting occurs only when the actual speed exits the defined speed window, preventing undesired shifts that would occur with simple automated control without continuous monitoring and comparison.
Solution Approach 2:
The system defines specific minimum and maximum speed parameter values (limit values) for each gear that characterize the speed window. By changing the control parameters from simple speed thresholds to multi-parameter comparisons (actual speed vs. minimum limit vs. maximum limit), the system achieves more reliable automated shifting decisions.
2Reliability
If multiple comparison criteria are used to determine shifting commands, then undesired shifts are avoided, but control device complexity increases
Solution Approach 1:
The control unit combines multiple comparison operations (comparing actual speed with minimum limit, comparing actual speed with maximum limit) into a single integrated control device. This merging of multiple comparison functions into one control unit achieves reliable shifting accuracy without proportionally increasing overall device complexity, as the comparisons are performed within a unified control architecture.
Solution Approach 2:
The control unit serves multiple functions: it determines the current gear, monitors actual speed parameters, compares speed with minimum and maximum limits, determines target gears, and issues shifting commands. This multi-functionality consolidates what would otherwise require separate devices into a single universal control unit, maintaining reliability while managing complexity.
3Ease of operation
If gear shifting is purely automated based on speed windows, then ease of operation improves, but adaptability to different driving conditions decreases
Solution Approach 1:
The control system dynamically adjusts the minimum and maximum speed parameter values (limit values) based on the selected driving mode. Instead of fixed speed windows, the system adapts the speed window characteristics to match different driving conditions, allowing the same automated control interface to serve multiple driving scenarios effectively.
Solution Approach 2:
The system changes the speed parameter limits according to the driving mode selection. By modifying the minimum and maximum speed values that define the speed window based on driving mode, the system maintains ease of automated operation while gaining adaptability to different driving conditions through parameter adjustment.
Data Source
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AI summary
The method involves determining an actual value, and determining a threshold value associated with the actual value. The actual value is compared with the associated threshold value. An actual speed characteristic value, a reference speed characteristic value, a result of comparison of speed with minimum and maximum values and a result of the comparison of the actual value with the associated threshold value are determined based on a switching command. Gears are replaced with respect to the switching command. An independent claim is also included for a control device for a hydrostatically driven multiple gear transmission.