Hydraulic Pump and Valve Layout for Low-Loss Flow Control
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Solution Overview
Problem
Traditional hydraulic systems for working vehicles face inefficiencies due to the need to restrict the flow of hydraulic fluid, which increases pressure and reduces efficiency, especially when multiple devices share a pump output, leading to parallel and confluence losses.
Innovation Solution
A hydraulic system with a variable output pump assembly and directional proportional control valves that independently control the flow to and from hydraulically actuated devices, allowing for separate management of inlet and outlet pressures without additional metering valves, and utilizing multiple pump assemblies to decouple devices and reduce sharing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the meter in area is restricted to control flow rate to a hydraulically-actuated device, then flow rate control is achieved, but pressure upstream of the proportional control valve increases which reduces system efficiency
Solution Approach 1:
The invention divides the hydraulic control system into separate inlet and outlet control paths. The inlet side uses a proportional control valve with meter in area for flow rate control, while the outlet side uses a separate proportional control valve with meter out area. This segmentation allows independent optimization of each control function, enabling flow rate control on the inlet side without the need to restrict outlet flow, thereby maintaining system efficiency.
2Reliability
If the meter out area is decreased to reduce flow rate and increase pressure for stable load control, then load stability is improved, but flow rate control is reduced
Solution Approach 1:
The invention separates the control functions by placing a proportional control valve on the outlet side of the hydraulically-actuated device. This allows the meter out area to be independently adjusted to maintain stable load control through increased back pressure, while the inlet side proportional control valve maintains flow rate control. The segmentation eliminates the trade-off between load stability and flow rate control.
3Device complexity
If multiple hydraulically-actuated devices share a single pump output, then system complexity is reduced, but parallel and confluence losses increase reducing efficiency
Solution Approach 1:
The invention introduces individual proportional control valves with independent meter in and meter out areas for each hydraulically-actuated device. This segmentation allows each device to be controlled independently, eliminating parallel and confluence losses that occur when multiple devices share a single pump output. The increased device complexity is offset by the significant reduction in energy losses.
4Quantity of substance
If the pump output is increased to supply multiple hydraulically-actuated devices, then flow availability is improved, but pressure losses in shared lines increase
Solution Approach 1:
The invention provides separate proportional control valves for each hydraulically-actuated device, creating independent flow paths. This segmentation allows the pump to supply adequate flow to multiple devices without suffering from pressure losses in shared lines, as each device has its own dedicated control path with independently adjustable meter in and meter out areas.
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
This configuration significantly reduces hydraulic system losses by up to 50%, improving controllability and efficiency, and reducing energy consumption in electric and fuel cell-powered vehicles.
Implementation Method 1
A downside of restricting the meter in area to control a flow of fluid to a hydraulically-actuated device is that it results in an increase in pressure upstream of the proportional control valve
Implementation Method 2
hydraulic pump assembly for supplying a variable output of hydraulic fluid to the hydraulically actuated device
Data Source
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AI summary
A hydraulic system for a working vehicle, the hydraulic system comprising: a hydraulically actuated device; a hydraulic pump assembly for supplying a variable output of hydraulic fluid to the hydraulically actuated device; and a proportional control valve, wherein the hydraulic system is arranged such that hydraulic fluid exiting the hydraulically actuated device flows through a restriction of the proportional control valve; and wherein the hydraulic system is configured to control a flow of hydraulic fluid supplied to the hydraulically actuated device by varying the output of hydraulic fluid from the hydraulic pump assembly, and to control a flow of hydraulic fluid exiting the hydraulically actuated device via adjusting a restriction area of the proportional control valve.