Hydraulic Pump Speed Control for Working Machine Fuel Efficiency
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Solution Overview
Problem
Working machines with internal combustion engine-driven hydraulic systems face inefficiencies in fuel consumption due to engine speed restrictions, leading to increased energy losses and fuel usage, especially when operators use maximal lever strokes without engine speed limitations.
Innovation Solution
A working machine configuration with an internal combustion engine, generator, and electric motor, where the hydraulic pump's drive source is separate from the electric motor, allowing speed control of the hydraulic pump to mimic conventional engine-driven systems, optimizing pump speed based on accelerator stroke, driveline power, and braking conditions to reduce energy losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hydraulic pump speed is increased to provide maximal flow for hydraulic actuators, then the hydraulic power and productivity are improved, but the fuel consumption increases due to unrestricted engine speed operation
Solution Approach 1:
The system dynamically adjusts pump speed based on actual hydraulic demand signals from control valves, rather than operating at fixed high speed. The pump controller continuously modifies pump operation parameters (speed, displacement) to match the instantaneous flow and pressure requirements of hydraulic actuators, resolving the contradiction between maintaining high productivity capability and reducing energy consumption during partial-load operations
Solution Approach 2:
The system changes the operating parameters of the hydraulic pump by controlling both speed and displacement based on demand signals. The pump controller receives hydraulic demand signals and adjusts pump parameters accordingly, allowing the system to operate at optimal efficiency points across varying load conditions rather than being locked into high-speed operation, thereby reducing fuel consumption while maintaining productivity when needed
2Use of energy by moving object
If the engine speed is restricted to match driveline requirements, then the fuel consumption is reduced, but the hydraulic pump flow capability is limited
Solution Approach 1:
The system dynamically decouples pump speed from engine speed by using an independent pump controller that receives hydraulic demand signals separately from driveline speed signals. This allows the pump to operate at optimal speeds for hydraulic performance independent of the engine's driveline-matched speed, resolving the contradiction between fuel efficiency and hydraulic flow capability
Solution Approach 2:
The control system is segmented into independent control loops: one for engine speed based on driveline requirements and another for pump speed based on hydraulic demands. The pump controller independently processes hydraulic demand signals from control valves and adjusts pump operation accordingly, allowing the pump to achieve required flow and pressure even when engine speed is restricted for fuel efficiency
3Productivity
If the operator uses maximal lever stroke for rapid bucket movement, then the productivity is improved, but the energy losses increase due to pressure drop over control valves
Solution Approach 1:
The system uses feedback from control valve positions and hydraulic demand signals to dynamically adjust pump output. The pump controller receives signals from control valves indicating actual hydraulic demands, allowing the pump to provide precisely the flow and pressure needed rather than excessive flow that would cause energy losses through pressure drops, thereby maintaining productivity while reducing energy waste
Solution Approach 2:
The system changes pump parameters (speed and displacement) based on real-time hydraulic demand signals from control valves. When the operator uses maximal lever stroke, the pump controller increases pump output parameters to match the demand, but only to the extent required, avoiding excessive flow that would create energy losses through pressure drops across control valves
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 configuration reduces fuel consumption by enhancing hydraulic pump efficiency, reducing pressure drop over control valves, and providing ergonomic 'on-off' control, balancing machine performance and fuel savings.
Implementation Method 1
an internal combustion engine 21, a generator 22, an energy storage 23 and an electric motor 24 for driving one or more wheels 25 of the working machine 1. The internal combustion engine 21 is arranged to drive the generator 22
Implementation Method 2
a hydraulic pump 27 for providing a hydraulic actuator 28 with hydraulic fluid
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a working machine (1) that comprises an internal combustion engine (21), a generator (22), an energy storage (23) and an electric motor (24) for driving one or more wheels (25) of the working machine. The internal combustion engine is arranged to drive the generator and the generator is arranged to supply power to the electric motor via the energy storage. The working machine further comprises an accelerator (33) for controlling the electric motor (24), and a hydraulic pump (27) for driving a hydraulic actuator (28). The hydraulic pump (27) has a drive source different from the electric motor (24) and the accelerator (33) is arranged for controlling the speed of the hydraulic pump (27).