Hydraulic Transmission Control for Constant-Speed ECO Driving
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Solution Overview
Problem
Existing hydraulic transmission systems in work and agricultural vehicles experience excessive fuel consumption when transitioning between work sites due to frequent switching between operating modes, especially on uneven terrain, leading to wear and inefficiency.
Innovation Solution
Implementing a dual control mechanism that maintains a constant prime mover rotation speed and adjusts hydraulic transmission ratios to maintain vehicle speed, while monitoring pressure thresholds to ensure optimal fuel efficiency in the ECO mode, even on slopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the transmission switches between accelerator-base mode and ECO mode based on monitoring conditions, then fuel consumption is reduced during steady-state operation, but frequent switching occurs on uneven terrain causing excessive wear and increased fuel consumption
Solution Approach 1:
The control system predicts upcoming slope changes using terrain information before the vehicle actually encounters them. This allows the system to prepare for potential mode switching scenarios in advance, maintaining stable operating conditions and avoiding frequent switching on uneven terrain by pre-adjusting transmission parameters according to predicted terrain conditions
Solution Approach 2:
The system continuously monitors actual terrain conditions and compares them with predicted conditions, using this feedback to adjust the mode switching decisions. When terrain variations are detected that would trigger frequent switching, the feedback mechanism maintains the current operating mode or adjusts parameters to prevent switching, thereby reducing transmission wear while still achieving fuel efficiency
2Use of energy by moving object
If the prime mover speed is reduced to an efficient operating point in ECO mode, then fuel consumption decreases, but vehicle speed must be maintained requiring complex transmission control
Solution Approach 1:
The control system is divided into separate functional modules: a prediction module that processes terrain information, a decision module that determines mode switching, and a control module that adjusts transmission parameters. This segmentation allows each module to perform its specific function independently, simplifying the overall control architecture while achieving the dual goals of fuel efficiency and speed maintenance
Solution Approach 2:
The system pre-calculates the required transmission parameter adjustments based on predicted terrain conditions and desired speed maintenance requirements. By preparing control commands in advance based on terrain predictions, the system avoids complex real-time calculations during mode transitions, thereby reducing control complexity while maintaining vehicle speed
3Productivity
If the transmission maintains constant vehicle speed during mode switching, then operational continuity is ensured, but fuel consumption increases during transitions
Solution Approach 1:
The system performs mode switching preparations in advance based on predicted terrain conditions, gradually adjusting transmission parameters before actual mode transition occurs. This preliminary adjustment reduces the magnitude and duration of speed fluctuations during switching, thereby reducing the energy required for corrective actions while maintaining operational continuity
Solution Approach 2:
The control system continuously adjusts transmission parameters to maintain vehicle speed throughout the mode switching process, ensuring that the useful action of vehicle propulsion continues without interruption. By maintaining continuous speed control rather than allowing speed to drop during transitions, the system ensures operational continuity while minimizing the additional fuel consumption associated with speed recovery
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
Reduces fuel consumption by up to 30% by maintaining the prime mover at an efficient operating point and minimizing transmission shifts, thus reducing wear and improving fuel efficiency during transitions.
Implementation Method 1
a hydraulic pump with variable displacement which powers a hydraulic motor
Implementation Method 2
a hydraulic motor which can have either fixed or variable displacement
Data Source
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AI summary
A method of controlling a propulsion system of a work or agricultural vehicle, in which the propulsion system comprises a prime mover (E) and a hydraulic transmission (HY) comprising a hydrostat wherein a variable displacement pump (HP) is configured to be driven in rotation by the prime mover and a variable displacement hydraulic motor (HM) is operatively connected to the pump by means of a delivery (F) and a return (R) hydraulic line, the method an operating mode (ST2) wherein said lever inclination value identifies a vehicle speed value, while the prime mover is operated at a predetermined, approximately fixed operating point, the method, in said operating mode, comprising a first process (P1) comprising the following steps in cyclic succession: (Step 11) monitoring the pressure inside the delivery line (F), (Step 12) first check if a pressure value of said monitored pressure exceeds a first predetermined threshold, in the positive case (12 = yes) then (Step 13) imposing a modification to the hydrostat configuration so that the measured pressure value is approximately equal to the first predetermined threshold, without changing the operating point of the prime mover.