Transmission Stage Changeover Control for Mobile Machines
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Solution Overview
Problem
Transmission stage changes in hydrostatic and mechanical manual transmission arrangements can lead to undesirable interruptions in tractive force, particularly when driving uphill or downhill, causing safety concerns and machine instability.
Innovation Solution
A method that estimates the vehicle's velocity at the end of a transmission stage changeover based on a requested time interval and compares it with reference values to determine if the changeover should be enabled or disabled, ensuring the changeover does not result in reduced or interrupted tractive force, thereby preventing critical situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If transmission stage changeover is enabled during travel, then automation and continuous operation are improved, but tractive force interruption and machine stability deteriorate
Solution Approach 1:
The control unit performs preliminary evaluation before enabling changeover by estimating the time required for stage transition and predicting whether tractive force will remain within acceptable ranges throughout the changeover period. This preliminary assessment prevents changeovers that would compromise machine stability.
Solution Approach 2:
The system continuously monitors actual velocity and compares it against predicted velocity profiles during changeover. This feedback mechanism allows the control unit to detect deviations and abort changeovers that would result in tractive force interruption, thereby maintaining machine stability.
2Adaptability or versatility
If transmission stage changeover is performed, then adaptability to varying speed requirements is improved, but tractive force reduction and safety deteriorate
Solution Approach 1:
Before executing a transmission stage changeover, the control unit estimates the changeover duration and evaluates whether the machine can maintain adequate tractive force throughout the transition. This preliminary check prevents changeovers that would create safety hazards due to insufficient tractive force.
Solution Approach 2:
The system monitors actual velocity and tractive force parameters during changeover execution. If measurements indicate that tractive force is approaching critical levels, the control unit aborts the changeover to prevent safety incidents, thus eliminating harmful effects while preserving adaptability.
3Ease of operation
If transmission stage changeover is enabled, then operational flexibility is improved, but hydrostatic braking performance and driver safety deteriorate
Solution Approach 1:
The control unit evaluates the machine's current operating state, including velocity and load conditions, before permitting transmission stage changeover. This preliminary assessment ensures that changeovers are only enabled when hydrostatic braking performance will not be compromised below safe thresholds.
Solution Approach 2:
During changeover execution, the system continuously monitors velocity and braking performance. If hydrostatic braking effectiveness drops below acceptable levels, the control unit aborts the changeover to maintain driver safety, thus preventing harmful effects while preserving operational flexibility.
Data Source
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AI summary
The present invention relates a method for changing over transmission stages (46, 48) of a transmission arrangement (3) of a mobile working machine, the transmission arrangement (3) comprising: a first hydraulic machine (8) coupled to a drive machine (2), a second hydraulic machine (14) having an adjustable expulsion volume (VH), wherein the second hydraulic machine (14) is fluidically connected to the first hydraulic machine (8) via a first working line (10) of the transmission arrangement (3) and a second working line (12) of the transmission arrangement (3), wherein the second hydraulic machine (14) is coupled to a manual transmission (6) of the transmission arrangement (3) so that a torque can be transmitted, the manual transmission (6) having at least two transmission stages (46, 48), the method being characterized in that it comprises the following steps: a) requesting a changeover of an engaged transmission stage (46, 48) from a first transmission stage (46, 48) to a second transmission stage (46, 48); b) identify a first time interval, wherein said first time interval is the time requested for shifting from said first transmission stage (46, 48) to said second transmission stage (46, 48); c) estimating the velocity reached by said mobile working machine at the end of said shifting based on said first time interval identified during said step b); d) enabling or disabling said changeover based on said estimated velocity.