Valve Block Bypass for Load Sensitivity
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Solution Overview
Problem
Closed center valve block systems lack the load sensitivity and flexibility of open center systems, making it difficult to implement desired load dependency and operational sensitivity in hydraulic systems, particularly in applications like excavator operations.
Innovation Solution
A closed center valve block arrangement with an electrically activated main spool and a bypass flow path controlled by an electrically activated cut valve, allowing for adjustable load sensitivity and open center behavior, which enables flexible load dependency and reduced sensitivity by varying the cut valve's opening cross-section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a closed center valve block is used, then the apparatus design is simple, but the system lacks load sensitivity and flexibility
Solution Approach 1:
The hydraulic system is segmented into two parallel supply paths: a main supply path through the closed center valve block and a bypass supply path through a bypass valve. This segmentation allows the system to combine the simplicity of closed center design with the load sensitivity of open center behavior, as the bypass path can be independently controlled to provide load-dependent flow regulation.
Solution Approach 2:
A bypass valve is introduced as an intermediary component between the pump and the main valve block. This bypass valve acts as a mediator that provides the missing load sensitivity function, allowing the system to achieve both simplicity (through the closed center valve block) and adaptability (through the bypass valve's load-dependent operation).
2Ease of operation
If high load sensitivity is implemented, then operational control is enhanced, but speed changes become noticeable when striking obstacles
Solution Approach 1:
The bypass valve is designed with adjustable opening cross-sections that can be dynamically modified to change the degree of load sensitivity. This dynamic adjustability allows the system to optimize between operational control (higher sensitivity) and speed stability (lower sensitivity) depending on the specific operational requirements, resolving the contradiction between enhanced control and noticeable speed changes.
3Adaptability or versatility
If a bypass flow path is added to achieve open center behavior, then load dependency is improved, but the apparatus complexity increases
Solution Approach 1:
The bypass valve is integrated into the existing hydraulic circuit in parallel with the main valve block, merging the closed center and open center functionalities into a single unified system. This combining approach allows the system to achieve load dependency characteristics without requiring a complete redesign of the valve block, thus improving adaptability while minimizing the increase in apparatus complexity.
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
The solution allows for the implementation of desired load dependency and reduced load sensitivity in closed center systems, mimicking open center behavior, thereby enhancing operational control and reducing the likelihood of unexpected speed changes during load encounters, such as striking an obstacle, while maintaining a simple apparatus design.
Implementation Method 1
A bypass flow path with a cut valve branches off between the, in particular adjustable, hydraulic machine and the main spool
Data Source
AI summary
A valve block arrangement configured as a closed center system includes at least one main spool for controlling a hydraulic consumer. The main spool is configured to open and close at least one pressure medium connection between a hydraulic pump and the consumer in controlled, continuous fashion and, in at least one embodiment, is electrically activated. A bypass flow path with a cut valve branches off between the adjustable, hydraulic pump and the main spool. The cut valve is configured to open and close a pressure medium connection between the hydraulic pump and a tank in controlled, continuous fashion. The cut valve is electrically activatable.