Load-Sensing Valve Pressure Relief for Idle Energy Reduction
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Solution Overview
Problem
In load sensing systems with fixed displacement pumps, energy is wasted as the same pressure difference (Δp) is applied even when idling, leading to unnecessary energy loss, especially in mobile hydraulics that operate for extended periods without active hydraulic use.
Innovation Solution
A valve with a pressure lowering device integrated in a screw-in housing that connects the spring chamber of the valve piston to the tank connection when idling, reducing system pressure, and automatically generates the required load sensing Δp when hydraulics are activated, utilizing a semi-piloted pressure compensator with no closing element on the pilot control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circulation pressure compensator is used to regulate system pressure in load-sensing systems, then the required load-sensing Δp is maintained for consistent speed control, but energy is wasted during idling when the same Δp is applied even though no hydraulic work is being performed
Solution Approach 1:
The pressure compensator is designed with dynamic pressure regulation capability that automatically adapts to system state. During idling, the compensator detects zero or minimal load-sensing pressure and reduces the pump pressure accordingly. When hydraulics are activated and load-sensing pressure rises, the compensator automatically restores the required load-sensing Δp for consistent speed control. This dynamic adaptation eliminates the need for manual intervention or complex control systems.
Solution Approach 2:
The pressure compensator autonomously monitors the load-sensing pressure and self-regulates the pump pressure without external control signals. The device uses its own internal sensing mechanism to detect whether the system is in idle or active state, and automatically adjusts the pressure differential accordingly. This self-service capability simplifies the overall system architecture while achieving energy savings during idling.
2Loss of energy
If system pressure is reduced during idling to save energy, then energy consumption decreases, but the ability to quickly respond when hydraulics are activated may be compromised
Solution Approach 1:
The pressure compensator maintains a ready-state configuration during idling that enables immediate pressure buildup when hydraulics are activated. Although the pump pressure is reduced during idle, the compensator's internal structure and spring mechanisms are pre-positioned to quickly establish the required load-sensing Δp as soon as load-sensing pressure appears. This preliminary preparation ensures rapid system response without sacrificing energy efficiency during idle periods.
Solution Approach 2:
The pressure compensator dynamically transitions between low-pressure idle state and high-pressure active state. The device incorporates fast-acting pressure-sensitive elements that detect the onset of hydraulic activation and trigger immediate pressure restoration. This dynamic response characteristic ensures that the system can quickly transition from energy-saving idle mode to full operational mode when needed.
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 solution reduces energy consumption during idling by lowering system pressure and ensures the required load sensing Δp is generated when needed, optimizing energy use in hydraulic systems.
Implementation Method 1
the same Δp is applied to the pump pressure... The pressure difference across a directional control valve is kept constant by connecting individual pressure compensators to the individual actuator ports
Implementation Method 2
The highest pressure occurring in the system in the lines to the actuators... is fed back to an inlet pressure compensator and compared with the system pressure currently delivered by the pump
Implementation Method 3
a valve with a valve housing and a valve piston which is guided longitudinally therein and which, under the action of a valve spring, blocks a fluid-carrying connection between a pressure connection and a tank connection
Implementation Method 4
a first pressure in the pressure line acts on a first pressure surface of the control piston, and a second pressure in a control line acts on a second pressure surface of the control piston in the opposite direction to the force acting on the first pressure surface
Data Source
Figure 1
Figure 2
AI summary
2. Valve comprising a valve housing (44) and a valve piston (46) longitudinally displaceable therein, which, under the influence of a valve spring (40), in its closed position blocks a fluid-carrying connection between a pressure port (32) and a tank port (48) in the valve housing (44) and releases it in an open position, and which has an orifice (56) that establishes a permanent fluid connection on the side of the pressure port (32) with a spring chamber (58) with the valve spring (40), and with a load-sensing port (64) in the valve housing (44) that opens into the spring chamber (58), characterized in that a pressure reduction device (68) is received in the valve housing (44) which, in the absence of pressure at the load-sensing port (64), fluid-carries the spring chamber (58) of the valve piston (46) with the tank port (48).