Hydraulic Equalization Valve for Mobile Construction Machines
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Solution Overview
Problem
Hydraulic systems in mobile construction machines, such as excavators, face challenges in maintaining sufficient pressure equalization and oil flow compensation during dynamic operations, especially with small pressure differences, which can lead to uneven load distribution and failure to meet safety standards when the equalization line bursts.
Innovation Solution
Incorporating a 2-way flow control valve with check valve function in the hydraulic system's equalization line, allowing for constant fluid equalization and ensuring that the maximum oil loss does not exceed 10 l/min per cylinder, even with small pressure differences, by connecting it to the compensating line and control pistons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If nozzles with limited flow rate are used to meet the 10 l/min oil loss standard, then oil loss is controlled, but sufficient equalization quantity cannot be provided for dynamic operation with small pressure differences
Solution Approach 1:
The patent applies a dynamically adjustable flow control valve instead of a fixed nozzle. The valve can adapt its opening cross-section based on operating conditions: it provides larger openings for dynamic equalization when pressure differences are small, and restricts flow to meet the 10 l/min standard when pressure differences are large or during static conditions. This dynamic adjustment resolves the contradiction between limiting oil loss and ensuring sufficient equalization quantity.
Solution Approach 2:
The patent changes the flow control parameter from a fixed nozzle opening to a variable opening controlled by a flow control valve. By adjusting the opening cross-section parameter dynamically, the system can provide sufficient equalization quantity (5-10 times larger than fixed nozzles) when needed while still limiting maximum oil loss to 10 l/min, thus resolving the contradiction between equalization effectiveness and oil loss control.
2Reliability
If a larger choke cross-section is installed to provide sufficient compensation, then dynamic equalization improves, but oil loss exceeds the 10 l/min standard
Solution Approach 1:
The flow control valve provides dynamic control of the choke cross-section, allowing it to be larger than fixed nozzles for better equalization performance while still limiting maximum flow to 10 l/min through active control. This resolves the contradiction by making the choke cross-section adaptively sized rather than fixed.
Solution Approach 2:
The flow control valve incorporates feedback control mechanisms that monitor pressure differences and adjust the choke opening accordingly. When pressure equalization is sufficient, the valve restricts flow to meet the 10 l/min standard; when pressure differences indicate need for equalization, the valve opens wider to provide compensation. This feedback mechanism resolves the contradiction between larger choke cross-section benefits and oil loss limitations.
3Reliability
If control pistons have identical opening cross sections, then symmetrical load holding is achieved, but tolerances and disturbance variables make this difficult to guarantee
Solution Approach 1:
The flow control valve acts as an intermediary device that compensates for control piston tolerances and disturbance variables. Instead of relying on precisely manufactured identical control pistons, the flow control valve actively adjusts flow distribution to achieve symmetrical load holding despite manufacturing variations. This intermediary mechanism resolves the contradiction by decoupling symmetrical performance from manufacturing precision requirements.
Solution Approach 2:
The flow control valve dynamically adjusts flow parameters to compensate for control piston variations. By changing flow distribution in real-time based on actual pressure differences and load conditions, the system achieves symmetrical load holding without requiring control pistons to have identical opening cross-sections within tight tolerances. This parameter adjustment approach resolves the contradiction between symmetrical performance and manufacturing variability.
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 guarantees a constant equalization quantity, ensuring safe and symmetrical load distribution during dynamic operations while meeting the standard oil loss criteria, and allows for a simple and compact design that can be retrofitted into existing systems.
Implementation Method 1
at least one 2-way flow control valve with a check valve function is connected to the at least one compensation line
Implementation Method 2
at least one equalization line for pressure equalization between the piston-cylinder units
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a hydraulic system with at least two piston cylinder units, at least one compensating line for pressure equalization between the piston cylinder units and control pistons, wherein each control piston is assigned to a connection of a piston cylinder unit, and wherein at least one 2-way flow control valve with check valve function is connected to the at least one compensating line.