Pressure Compensation Unit With Shared Relief Line
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Solution Overview
Problem
In load-sensing hydraulic circuits, existing pressure compensation units experience unnecessary hydraulic fluid flow and energy loss when the load pressure of one actuator exceeds the relief valve setting, causing energy inefficiency and disrupting the flow rate to other actuators.
Innovation Solution
A pressure compensation unit design that includes a control valve, pressure compensation valve, load pressure detection line, relief line with a relief valve, and a switching valve that adjusts signal pressure based on fluid flow through the relief line, preventing unnecessary flow by isolating non-operating units and maintaining desired load pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relief valve is provided in the relief line of each pressure compensation unit, then the load pressure of an actuator can be kept to a desired pressure or lower, but when the load pressure exceeds the relief valve setting, hydraulic fluid flows through the relief valve causing energy loss and disrupting flow rate to other actuators
Solution Approach 1:
The patent merges the relief line of each pressure compensation unit into a common shared relief line. When any actuator's load pressure exceeds the relief valve setting, the relief valve opens to discharge hydraulic fluid through this shared line, preventing energy loss in non-operating units while maintaining load pressure control for all actuators.
Solution Approach 2:
The shared relief line serves multiple functions: it provides pressure relief for all pressure compensation units simultaneously, enables centralized flow management, and prevents unnecessary energy loss in inactive units while maintaining reliability of load pressure control across the entire hydraulic system.
2Loss of energy
If the relief valve setting is lowered to prevent energy loss, then energy efficiency improves, but the maximum load pressure that can be achieved is reduced
Solution Approach 1:
The system dynamically switches between pressure compensation mode and pressure restriction mode based on operating conditions. The relief valve setting remains high to enable maximum load pressure when needed, while the shared relief line dynamically activates only when pressure exceeds the setting, preventing energy loss during normal operation while maintaining high pressure capability when required.
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 ensures constant hydraulic fluid flow rate and prevents energy loss by isolating non-operating units, maintaining desired load pressure, and preventing hydraulic fluid from flowing through relief valves of inactive pressure compensation units.
Implementation Method 1
a pressure compensation valve (4) connected to the pair of relay ports (32) by an upstream-side relay line (41) and a downstream-side relay line (42), and moving in accordance with a pressure difference between a pressure of the upstream-side relay line (41) and a signal pressure
Implementation Method 2
a relief line (61) connected to the downstream-side relay line (42) and provided with a relief valve (62)
Implementation Method 3
a switching valve (7) configured to: lead a maximum load pressure to the pressure compensation valve (4) as the signal pressure when the hydraulic fluid does not flow through the relief line (61); and lead a pump pressure to the pressure compensation valve (4) as the signal pressure when the hydraulic fluid flows through the relief line (61)
Data Source
AI summary
A pressure compensation unit includes: a control valve controlling hydraulic fluid supply and discharge to and from an actuator, the control valve including a pump port, a pair of relay and supply/discharge ports, and a tank port; a pressure compensation valve connected to the relay ports by an upstream and downstream-side relay lines, the pressure compensation valve moving in accordance with a pressure difference between upstream-side relay line and signal pressure; a load pressure detection line branching from the downstream-side relay line; a relief line connected to the downstream-side relay line and having a relief valve; and a switching valve leading: a maximum load pressure to the pressure compensation valve as the signal pressure when the hydraulic fluid does not flow through the relief line; and a pump pressure to the pressure compensation valve as the signal pressure when the hydraulic fluid flows through the relief line.