Hydraulic Control Valve Flowrate Shifting to Cut Horsepower Loss
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Solution Overview
Problem
Conventional hydraulic systems for working machines, such as skid steer loaders and compact track loaders, experience horsepower loss due to variability in hydraulic fluid flowrate, which is not effectively managed by existing variable displacement pumps and control valves.
Innovation Solution
A hydraulic system with a variable displacement pump and multiple control valves, including a boom control valve, working tool control valve, and auxiliary control valve, that can shift between reduction and increase positions to optimize hydraulic fluid flowrate to hydraulic actuators, minimizing horsepower loss by adjusting flowrate based on operational demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a variable displacement hydraulic pump is used to deliver hydraulic fluid with variable flowrate, then each hydraulic actuator can be supplied with hydraulic fluid corresponding to its required flowrate, but horsepower loss may occur depending on the generated amount of LS differential pressure
Solution Approach 1:
The control valve is designed with a movable spool that can dynamically shift between neutral position, reduction position, and increase position. This dynamic adjustment allows the system to change the flowrate of hydraulic fluid in real-time based on operational demands, resolving the contradiction between maintaining variable flowrate for productivity and minimizing energy loss by avoiding constant high-pressure differential.
Solution Approach 2:
The invention changes the flowrate parameter of hydraulic fluid by introducing flowrate reduction and increase sections within the control valve. When the spool shifts to the reduction position, the flowrate reduction section decreases the flowrate; when shifted to the increase position, the flowrate increase section increases the flowrate. This parameter adjustment allows the system to match flowrate to actual demands, reducing unnecessary horsepower loss while maintaining productivity.
2Loss of energy
If the control valve shifts to the reduction position to minimize horsepower loss, then flowrate is reduced, but this may not satisfy operations requiring large flowrate
Solution Approach 1:
The control valve's spool can dynamically shift between neutral position, reduction position, and increase position based on operational demands. When high flowrate is needed, the spool shifts to the increase position, activating the flowrate increase section to deliver large flowrate to satisfy productivity requirements while still allowing for energy efficiency when high flowrate is not needed.
Solution Approach 2:
The control valve is designed with multi-functionality to handle different operational scenarios. It can operate in neutral position for normal flowrate, shift to reduction position for energy-saving mode, or shift to increase position for high-flowrate demands. This universal design allows a single valve to satisfy both energy efficiency and productivity requirements under different conditions.
3Ease of operation
If the control valve maintains constant LS differential pressure, then flowrate can be controlled, but this generates horsepower loss
Solution Approach 1:
The invention changes the pressure parameter dynamically by introducing flowrate reduction and increase sections that modify the LS differential pressure based on spool position. When the spool is in the reduction position, the flowrate reduction section decreases both flowrate and pressure to minimize horsepower loss. When in the increase position, the flowrate increase section restores pressure and flowrate to meet operational demands. This parameter adjustment resolves the contradiction between ease of flowrate control and energy efficiency.
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 effectively minimizes horsepower loss by optimizing hydraulic fluid flowrate to hydraulic actuators, ensuring efficient operation and balanced work performance across various loads and operations.
Implementation Method 1
a variable displacement hydraulic pump to deliver hydraulic fluid having a variable flowrate
Implementation Method 2
a plurality of control valves each of which is shiftable among a plurality of shift positions so that the control valve, when shifted to one of the shift positions, controls a flowrate of hydraulic fluid flowing to the corresponding hydraulic actuator
Implementation Method 3
a flowrate reduction section configured so that, when the control valve is shifted to a reduction position serving as a specific one of the shift positions, the flowrate reduction section reduces a flowrate of the hydraulic fluid entering the input port and outputs the flowrate-reduced hydraulic fluid to the output port
Implementation Method 4
a flowrate increase section configured so that, when the control valve is shifted to an increase position serving as another shift position different from the specific one of the shift positions, the flowrate increase section outputs the hydraulic fluid having entered the input port to the output port at a flowrate larger than that of hydraulic fluid output by the flowrate reduction section
Data Source
AI summary
A hydraulic system for a working machine includes a variable displacement hydraulic pump, a plurality of hydraulic actuators, and a plurality of control valves. Each of the control valves includes an input port, an output port, and a flowrate reduction section. At least one of the control valves includes a flowrate increase section. The hydraulic actuators are a boom cylinder, a working tool cylinder, and an auxiliary actuator. The control valves are a boom control valve for controlling the boom cylinder, a working tool control valve for controlling the working tool cylinder, and a first auxiliary control valve for controlling the auxiliary actuator. The boom control valve and the working tool control valve each include the flowrate reduction section, and the first auxiliary control valve includes the flowrate reduction section and the flowrate increase section.