Electro-hydraulic Pump Control via Pressure Feedback
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Solution Overview
Problem
Hydraulic systems for work machines face inefficiencies in fluid flow control, particularly in diverting and exhausting fluid to actuators, leading to suboptimal performance and energy wastage due to the lack of precise pressure management and adaptive displacement control.
Innovation Solution
An electro-hydraulic system incorporating a variable displacement fluid pump, directional control valve, sensor, and controller that adjusts the pump's displacement based on pressure differences and flow requirements, allowing for efficient fluid diversion to actuators and optimized energy use by modifying the pump's operation in response to sensed pressures and predetermined flow commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a fixed displacement pump is used in the hydraulic system, then the system structure is simple, but energy is wasted due to continuous fluid flow regardless of operational demands
Solution Approach 1:
The patent applies a variable displacement pump that dynamically adjusts its fluid flow output based on real-time pressure feedback from the hydraulic system. The pump displacement is modulated to match actual operational demands, converting the static fixed-displacement system into a dynamic adaptive system that reduces energy waste while maintaining operational simplicity through electronic control.
Solution Approach 2:
The patent implements a feedback control mechanism where a pressure sensor continuously monitors the hydraulic system pressure and sends signals to the controller, which then adjusts the variable displacement pump's output accordingly. This closed-loop feedback system enables the pump to automatically reduce fluid flow when system pressure is sufficient, eliminating energy waste without requiring complex mechanical valves or couplings.
2Device complexity
If mechanical valves and couplings are used for flow control, then the system is reliable, but the system complexity and cost increase
Solution Approach 1:
The patent replaces traditional mechanical flow control valves and couplings with an electro-hydraulic control system. The variable displacement pump, controlled by electronic signals from a controller based on pressure sensor feedback, substitutes for mechanical valve operations. This substitution reduces the number of mechanical moving parts, simplifying the system while maintaining or improving reliability through electronic control.
3Productivity
If fluid is continuously diverted to actuators, then the actuators remain ready for operation, but energy is wasted when actuators are not needed
Solution Approach 1:
The variable displacement pump dynamically adjusts its fluid delivery rate based on real-time system pressure feedback. When actuators are not actively needed, the pump reduces or stops fluid diversion, maintaining operational readiness only when necessary. This dynamic adjustment eliminates continuous energy waste while preserving the ability to quickly respond to operational demands.
Solution Approach 2:
The system changes the flow rate parameter of the hydraulic pump based on pressure conditions. When system pressure indicates that actuators are sufficiently charged or not needed, the pump's displacement parameter is reduced or set to zero, stopping unnecessary fluid flow. This parameter modulation allows the system to maintain operational readiness on-demand rather than continuously, reducing energy waste.
Data Source
AI summary
A fluid power system includes an electro-hydraulic variable displacement fluid pump driving fluid at a first displacement value. The system further includes a directional control valve, a sensor, and a controller. The directional control valve includes a valve member movable between a neutral position and at least one actuated position. The directional control valve diverts at least some fluid to an actuator while the valve member is in an actuated position, and the directional control valve exhausts fluid at an exhaust pressure through an outlet port to the fluid reservoir while the valve member is in the neutral position. The sensor measures a difference between the exhaust pressure and a nominal pressure and generates a signal based on the measured difference. The controller generates a flow command at least partially based on the pressure signal to modify the operation of the pump to drive fluid at a second displacement value.