Tractor Drive System Torque Continuity
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Solution Overview
Problem
Agricultural vehicles, particularly tractors, face challenges with existing drive systems that result in torque interruptions and discomfort due to insufficient speed range and high tractive effort, leading to uncomfortable gear shifts and potential vehicle stoppages during load changes.
Innovation Solution
The implementation of a drive system with two synchronously coupled electric machines that can switch operating states without torque interruptions, using a third electric machine to ensure continuous torque delivery and avoid gear ratio jumps, allowing for smooth transitions between different operating modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electric machine is used to drive the vehicle, then the device complexity is reduced, but torque interruptions and non-uniformities occur during wiring changes
Solution Approach 1:
The drive system is segmented into multiple electric machines (first, second, and third electric machines) that can operate independently or in combination. This segmentation allows the system to switch between different machine configurations without interrupting torque delivery, as one machine can maintain operation while another undergoes wiring changes or operates in different modes.
Solution Approach 2:
The third electric machine acts as an intermediary that facilitates smooth transitions between operating states of the second electric machine. When the second electric machine needs to change wiring or operating mode, the third electric machine compensates to maintain continuous torque delivery to the mechanical output interface.
2Adaptability or versatility
If the second electric machine changes wiring during operation, then adaptability to different operating states is improved, but torque interruptions or non-uniformities occur
Solution Approach 1:
The system performs preliminary actions by having the third electric machine ready to compensate before the second electric machine undergoes wiring changes. The control unit coordinates the timing of wiring changes with the operational state of the third machine, ensuring that torque delivery remains continuous and uniform throughout the transition.
Solution Approach 2:
The system maintains continuous useful action (torque delivery) during wiring changes of the second electric machine by having the third electric machine compensate for any temporary reduction in torque output. This ensures that the vehicle experiences no interruptions or non-uniformities in torque delivery, maintaining driving comfort during operating state transitions.
3Speed
If gear ratio jumps are used to cover speed range, then the speed range is improved, but shift jerk and discomfort increase
Solution Approach 1:
The system uses dynamic control of multiple electric machines to continuously adjust the effective gear ratio without discrete jumps. By varying the operating states and torque contributions of the first, second, and third electric machines, the system achieves smooth transitions between different speed ranges, eliminating shift jerks while maintaining an extended effective speed range.
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 enables tractors to maintain continuous operation and comfort by avoiding torque interruptions and non-uniformities during speed changes, ensuring reliable performance across varying load conditions.
Implementation Method 1
zwei elektrischen Maschinen (22, 24), deren Rotoren (34, 36) jeweils mit Welle (40, 42) verfestigt drehverbunden sind
Implementation Method 2
eine von der Antriebsmaschine (12) angetriebene Welle (14) drehverbunden mit der Welle (38) des Rotors (32) des ersten elektrischen Maschinen (20)
Data Source
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AI summary
The invention relates to a drive system (10) for an agricultural or industrial utility vehicle, preferably a tractor. Said drive system (10) comprises a drive assembly (12) that generates a mechanical torque, a first and a second electric machine (20, 22), a first mechanical output interface (16) used to drive at least one vehicle axle and a second mechanical output interface (18). An electric machine (20, 22) comprises a rotor (32, 34) which is connected to a shaft (38, 40) in a rotationally fixed manner. A shaft (14) driven by the drive assembly (12) is rotationally connected to the shaft (38) of the first electric machine (20). The second output interface (18) is used to mechanically drive a tool which can be coupled to the utility vehicle. The shaft (40) of the second electric machine (22) can be reversibly connected to the first mechanical output interface (16). The invention also relates to an agricultural or industrial utility vehicle, especially a tractor, comprising said drive system (10). In order to allow for a connection modification of the second electric machine without producing interruptions or irregularities of torque, a third electric machine (24) is provided the shaft (42) of which can be reversibly connected to the first mechanical output interface (16). The invention is further characterized in that the shafts (40, 42) of the second and third electric machine (22, 24) can be coupled so as to be synchronous.