Pilot Hydraulic Pump Flow Control for Excavator Energy Savings
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Solution Overview
Problem
Existing work machines, such as hydraulic excavators, face issues with energy wastage and operability due to the pilot hydraulic pump supplying pressure oil even when hydraulic actuators are not in use, leading to decreased responsiveness and increased energy consumption.
Innovation Solution
A work machine with a controller that adjusts the discharge flow rate of the pilot hydraulic pump to match the sum of requested pilot flow rates and a preset standby flow rate, ensuring efficient energy use and maintaining operability by preventing response delays and deceleration of hydraulic actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pilot hydraulic pump is driven by a fixed displacement design connected to the engine, then the system is simple and reliable, but energy is wasted when hydraulic actuators are not in use
Solution Approach 1:
The pilot hydraulic pump is designed with variable displacement capability, allowing the discharge flow rate to be dynamically adjusted based on the actual operating conditions. The controller varies the pump displacement to match the required pilot flow rate, reducing energy consumption when actuators are not in use while maintaining system simplicity
Solution Approach 2:
The discharge flow rate of the pilot hydraulic pump is controlled by changing the displacement parameter. The controller adjusts the pump displacement according to the sum of requested pilot flow rates from all actuators plus a standby flow rate, optimizing energy efficiency without complex additional components
2Loss of energy
If the pilot hydraulic pump discharge flow rate is reduced to save energy, then energy consumption decreases, but the responsiveness and operability of hydraulic actuators deteriorates
Solution Approach 1:
The controller pre-calculates the required pilot flow rate by summing the requested flow rates from all hydraulic actuators and adding a standby flow rate. This preliminary calculation ensures that sufficient pilot oil is always available when actuators need to operate, maintaining responsiveness while avoiding excessive flow rate that would waste energy
Solution Approach 2:
The controller continuously monitors the operating states of all hydraulic actuators and adjusts the pilot hydraulic pump discharge flow rate in real-time based on the sum of requested pilot flow rates. This feedback mechanism ensures optimal energy efficiency while maintaining actuator responsiveness
3Ease of operation
If the pilot hydraulic pump supplies excess discharge flow rate to ensure actuator responsiveness, then operability is maintained, but energy is wasted
Solution Approach 1:
The discharge flow rate parameter of the pilot hydraulic pump is dynamically adjusted based on actual operating conditions. The controller calculates the required flow rate as the sum of requested pilot flow rates from all actuators plus a standby flow rate, optimizing the balance between operability and energy consumption
Data Source
AI summary
A hydraulic excavator 1 includes an engine 16, a main hydraulic pump 17 driven by the engine 16, a plurality of hydraulic actuators driven with pressure oil discharged from the main hydraulic pump 17, a plurality of flow rate control valves adapted to control the flow rate of pressure oil to be supplied from the main hydraulic pump 17 to the respective hydraulic actuators, a pilot hydraulic pump 18 adapted to supply pressure oil for driving the flow rate control valves, and a controller 15 configured to control the discharge flow rate of the pilot hydraulic pump 18. The controller 15 controls the discharge flow rate of the pilot hydraulic pump 18 such that it becomes equal to the sum of requested pilot flow rates determined in accordance with control commands for the respective flow rate control valves and a preset standby flow rate.