Hybrid Drive System Torque Converter Slip Control
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Solution Overview
Problem
Hybrid drive systems in construction machines face inefficiencies due to the interaction between driveline and work hydraulics, leading to increased fuel consumption and energy losses, particularly in operations with high torque converter slip.
Innovation Solution
A method and system that determine the engine speed based on torque converter slip to optimize energy utilization from the energy storage system, minimizing power from the combustion engine and reducing torque converter losses by distributing energy efficiently between the engine and energy storage system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the energy storage system is utilized to provide power for vehicle propulsion, then fuel efficiency is improved, but the complexity of the drive system increases
Solution Approach 1:
The drive system is segmented into distinct power sources (combustion engine and energy storage system) and control modules. The combustion engine handles base load power requirements while the energy storage system provides supplemental power during high-demand periods, allowing each component to operate independently and be optimized separately, thus managing overall system complexity.
Solution Approach 2:
A control unit acts as an intermediary between the combustion engine, energy storage system, and drivetrain components. This mediator coordinates power distribution, manages energy flow, and balances the operational demands of both power sources, simplifying the integration complexity through centralized intelligent control.
2Loss of energy
If the engine speed is reduced to minimize torque converter slip, then energy losses are reduced, but the power provided by the engine decreases
Solution Approach 1:
The system merges the power output of the combustion engine with the energy storage system to meet total power requirements. When the engine operates at reduced speeds to minimize torque converter slip, the energy storage system compensates for the reduced engine power, maintaining overall system power output while reducing energy losses.
Solution Approach 2:
The system dynamically adjusts the operational mode between engine-only, hybrid, and energy storage-only propulsion based on real-time conditions including torque converter slip, power demand, and energy storage state of charge. This dynamic adaptation allows the system to optimize the balance between minimizing losses and maintaining sufficient power delivery.
3Use of energy by moving object
If the energy storage system provides maximum power for vehicle propulsion, then fuel consumption is reduced, but the available energy in the energy storage system is depleted faster
Solution Approach 1:
The energy storage system operates in periodic cycles of charging and discharging. During high-power demand periods, it discharges to supplement engine power and reduce fuel consumption. During lower demand periods or regenerative braking events, it recharges. This periodic operation extends the effective duration of energy storage utilization throughout the work cycle.
Solution Approach 2:
The system recovers energy during regenerative braking events and periods of excess engine power, storing it in the energy storage system for later use. This recovery mechanism replenishes the energy storage system, extending its operational duration and allowing repeated cycles of high-power supplemental assistance without permanent depletion.
Data Source
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AI summary
The invention relates to a method and a system for controlling a drive system (300) in a working machine (101). The system comprises an internal combustion engine (301); a torque converter (302) having an input shaft (304) operatively coupled to the engine and an output shaft (306) operatively coupled to a gearbox (308); an energy storage system (310) coupled to the gearbox for providing power to a drive shaft (314) of the vehicle via the gearbox; and work hydraulics (314) operatively connected to the engine. The method comprises determining (S1) a requested power for vehicle propulsion; determining (S2) an available amount of energy in the energy storage system. The method further comprises, determining (S3), based on a predetermined amount of energy to be provided from the energy storage system for vehicle propulsion, a torque converter slip and determining (S4) an engine speed based on the torque converter slip such that the power provided by the engine combined with the power provided the energy storage system equals the requested power for vehicle propulsion.