Hydraulic Pump Flow Matching for Energy-Efficient Actuator Control
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Solution Overview
Problem
Construction machines, particularly light-weight demolition robots, face inefficiencies in energy usage due to reliance on combustion engines or electrical mains, leading to high energy consumption and environmental impact, with existing hybrid electric solutions not fully addressing energy efficiency needs.
Innovation Solution
A hydraulic system for construction machines featuring a pump, tank, actuator control valves, and a control unit that configures valve positions to deliver hydraulic flow at or below the total actuator requirement, eliminating excess flow and pressure, and allowing for a boost mode for increased performance, utilizing pressure compensated and non-compensated valves, and load sensing systems to determine flow requirements efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional hydraulic systems generate pressure above load pressure by a margin to ensure adequate flow supply, then reliable actuator operation is maintained, but energy consumption increases and system efficiency deteriorates
Solution Approach 1:
The system dynamically adjusts pump flow output based on real-time actuator requirements by controlling the spool position of the compensating valve, transitioning from static pressure maintenance to dynamic flow matching. This resolves the contradiction by making the hydraulic supply adaptive rather than fixed, ensuring reliability only when needed while minimizing energy consumption during normal operation.
Solution Approach 2:
The system uses feedback from actuator flow requirements to control pump output through the compensating valve mechanism. The feedback loop monitors actual actuator needs and adjusts pump flow accordingly, eliminating the need for fixed pressure margins and reducing energy waste while maintaining actuator reliability through demand-responsive supply.
2Use of energy by moving object
If pressure compensated flow control valves are used to precisely match pump flow to actuator requirements, then energy efficiency improves, but system complexity and control difficulty increase
Solution Approach 1:
The system employs a pressure compensated flow control valve (compensating valve) that uses hydraulic pressure differential mechanisms to automatically regulate flow. The compensating valve utilizes pressure zones and spring forces to maintain constant pressure differential across the valve, providing passive flow compensation without requiring complex electronic controls, thus improving energy efficiency while limiting complexity growth.
Solution Approach 2:
The compensating valve performs self-regulation of pump flow based on actuator demand through its inherent pressure-compensated mechanism. The valve automatically adjusts its opening to maintain constant pressure differential and regulate flow without external intervention, making the system energy-efficient while avoiding the need for complex active control systems.
3Reliability
If hydraulic pump delivers flow above actuator requirements to ensure adequate supply, then actuator performance is maintained, but excess flow causes energy waste and heat generation
Solution Approach 1:
The system applies partial action by delivering exactly the flow amount needed by actuators rather than excessive flow. The compensating valve regulates pump output to match actuator requirements precisely, eliminating the traditional practice of over-supplying flow. This resolves the contradiction by providing sufficient flow for actuator performance while avoiding the energy waste associated with excessive flow delivery.
Solution Approach 2:
The system changes the flow parameter dynamically to match actuator demands rather than maintaining constant excessive flow. The compensating valve adjusts pump flow rate based on actual system needs, transforming the hydraulic system from a constant-flow architecture to a variable-flow architecture, thereby reducing energy loss while maintaining actuator performance.
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
The system achieves improved energy efficiency by reducing excess flow and pressure, resulting in energy savings of up to 10% and enabling efficient operation without the need for pressure transducers, while maintaining performance through adjustable modes of operation.
Implementation Method 1
at least one of the actuator control valves is a pressure compensated flow control valve
Implementation Method 2
a hydraulic pump, a hydraulic tank, one or more actuator control valves arranged to control respective actuators
Implementation Method 3
each valve comprises a sensor arrangement configured to sense a differential pressure over the valve
Data Source
AI summary
A hydraulic system (400) for a construction machine, the system comprising a hydraulic pump (410), a hydraulic tank (420), one or more actuator control valves (430, 440) arranged to control respective actuators on the construction machine, and a control unit (300) arranged to configure respective valve positions of the actuator control valves and to control a hydraulic flow generated by the pump (410), wherein at least one of the actuator control valves (430, 440) is a pressure compensated flow control valve, and where, in a first mode of operation, the control unit (300) is arranged to control the hydraulic pump (410) to deliver a hydraulic flow at a pre-determined flow level at or below a total flow requirement of the actuators.