Proportional Valve Sliding Piston for Dynamic Pressure Limiting
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Solution Overview
Problem
Existing control devices with proportional spool valves and secondary pressure relief systems waste hydraulic energy due to constant pressure operation when the hydraulic consumer is not actively engaged, leading to unnecessary energy loss in applications like forestry cranes and excavators.
Innovation Solution
Implementing a two-stage secondary pressure limitation system within the same deflection stroke of the piston valve, allowing for a lower limit value in one part and a higher limit value in another, with the ability to change limits dynamically via secondary pressure relief valves and an inflow regulator, ensuring energy efficiency by only applying full pressure when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant limit value is set for the secondary pressure relief valve, then the hydraulic consumer can be actuated reliably, but hydraulic energy is wasted unnecessarily when the consumer is not actively engaged
Solution Approach 1:
The patent applies dynamics by making the limit value of the secondary pressure relief valve changeable during operation. The control device adjusts the limit value dynamically based on the deflection stroke of the spool: a first limit value is active during part of the deflection stroke, and a second (lower) limit value is active during another part. This dynamic adjustment allows the system to maintain reliable actuation when needed while reducing energy consumption during idle periods.
Solution Approach 2:
The patent implements parameter changes by varying the pressure limit parameter of the secondary pressure relief valve. The control device changes the limit value parameter from a first limit value to a second limit value depending on the operational phase (deflection stroke position). This parameter change enables the system to optimize between reliability and energy efficiency by adapting the pressure parameter to actual operational requirements.
2Ease of operation
If a proportional spool valve is used for movement control, then the hydraulic consumer can be precisely controlled, but the system operates as a constant pressure system causing energy dissipation
Solution Approach 1:
The patent combines the proportional spool valve for precise movement control with a dynamically adjustable secondary pressure relief valve. While the spool valve maintains ease of operation and control precision, the secondary pressure relief valve's limit value changes during the deflection stroke, transforming the constant pressure system into a variable pressure system that reduces energy dissipation.
Solution Approach 2:
The patent applies periodic action through the cyclic change of the secondary pressure relief valve's limit value during each deflection stroke cycle. The control device alternates between the first and second limit values in different phases of the operational cycle, creating a periodic pattern that reduces overall energy consumption while maintaining control precision through the spool valve.
3Stability of the object's composition
If the secondary pressure relief valve responds at a constant limit value, then the load pressure signal circuit becomes a constant pressure system, but unnecessary hydraulic energy is dissipated when the consumer stops
Solution Approach 1:
The patent transforms the static constant pressure system into a dynamic variable pressure system. The secondary pressure relief valve's limit value is no longer constant but changes during the deflection stroke, with a first limit value during part of the stroke and a second limit value during another part. This dynamic behavior maintains system stability when needed while eliminating unnecessary energy dissipation during idle periods.
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 approach minimizes hydraulic energy losses by adjusting pressure limits based on the operational need, reducing energy consumption and improving operational efficiency in hydraulic systems.
Implementation Method 1
the load pressure is acted upon by a secondary pressure relief valve 2, 3 and is limited by this to a defined maximum value
Implementation Method 2
actuated by a proportional magnet
Implementation Method 3
via an inflow regulator, the actuating pressure of the hydraulic consumer increases
Data Source
Figure 1
Figure 2~5
Figure 6~8
AI summary
In a control device S with a proportional directional control valve 1 containing a slide piston R, and with at least one secondary pressure relief valve 2, 3, with which a limit value P1, P2 of the secondary pressure 35 can be set in a load pressure signal circuit LS, the limit value P1, P2 can be changed when the slide piston R is deflected from a neutral position within the same deflection stroke. In a proportional directional control valve slide piston, a first axially limited bridging structure 20 is provided for interaction with a first pair of connections 12, 13, and at least a second bridging structure 24 is provided axially offset from the first bridging structure 20 for simultaneous interaction with a second pair of connections within at least a part of the same deflection stroke.