Hydraulic Valve Interlocking for Flowrate Matching and Lower Horsepower Loss
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Solution Overview
Problem
Conventional hydraulic systems for working machines, such as skid steer 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, multiple shiftable control valves, a detection fluid passage, and a pressure detection unit, where the control valves include flowrate reduction and increase sections, and an interlocking control valve to optimize pilot pressure and flowrate based on operation member input, minimizing horsepower loss.
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 at the required flowrate, but horsepower loss occurs due to variability in flowrate
Solution Approach 1:
The control valve is segmented into multiple shift positions (first shift position, second shift position, third shift position) with different flowrate control characteristics. This allows the system to select appropriate flowrate reduction levels based on operational needs, thereby matching the variable pump output to specific actuator requirements while minimizing unnecessary flowrate variation and horsepower loss.
Solution Approach 2:
The control valve dynamically shifts between multiple positions to adapt its flowrate control characteristics. By transitioning between first, second, and third shift positions, the valve can provide different degrees of flowrate reduction, enabling real-time optimization of hydraulic fluid delivery to match actuator demands and reduce horsepower loss from flowrate variability.
2Adaptability or versatility
If control valves are made shiftable among multiple positions to control flowrate, then flowrate can be adjusted for different actuators, but device complexity increases
Solution Approach 1:
The control valve is designed with multi-functionality, serving as both a directional control valve and a flowrate control valve. By integrating multiple control functions into a single valve component that can shift between first, second, and third positions, the system achieves flowrate adjustment capability without proportionally increasing the number of separate control components, thus managing complexity while enhancing versatility.
3Productivity
If flowrate reduction section is added to control valve, then flowrate can be reduced for specific actuators, but manufacturing complexity increases
Solution Approach 1:
The flowrate reduction function is merged into the control valve's internal structure rather than being implemented as a separate external component. The flowrate reduction section is integrated within the valve body, allowing flowrate control to be achieved through the valve's shifting mechanism itself. This integration simplifies manufacturing by combining multiple functions in a single component rather than assembling separate parts.
Data Source
AI summary
A hydraulic system for a working machine includes hydraulic actuators actuated with hydraulic fluid delivered from a hydraulic pump, control valves each of which is shiftable among shift positions to control a flowrate of hydraulic fluid flowing to the corresponding hydraulic actuator, a detection fluid passage, an interlocking control valve, and a pressure detection unit. Each control valve includes an input port, an output port, and a flowrate reduction section. One of the control valves includes a flowrate increase section. The interlocking control valve is configured to be shifted in accordance with a shift of the one of the control valves among the shift positions and to be shifted to a blocking position to block a pilot fluid introduced into the interlocking control valve from the detection fluid passage when the one of the control valves is shifted to the increase position.