Hydraulic Valve Control for Independent Supply and Discharge Flow
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Solution Overview
Problem
The existing hydraulic control systems for working machines with hydraulic actuators face inefficiencies in controlling supply and discharge flow rates, particularly when operating with multiple actuators or varying load conditions, due to the fixed relationship between supply and discharge flow rates, leading to degraded operability and working efficiency.
Innovation Solution
A hydraulic control system with a direction change-over valve and flow control valve configuration, where the flow control valve is positioned upstream to control the supply flow rate based on the operating conditions of the hydraulic actuator, allowing for independent control of supply and discharge flow rates through precise adjustment of valve openings and differential pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the opening area of the supply valve passage in the direction change-over valve is made large to allow supply flow to pass without pressure difference, then the supply flow can run as-is into the hydraulic actuator, but the direction change-over valve becomes considerably large in size
Solution Approach 1:
The patent divides the supply flow control function into two separate components: the direction change-over valve (which only changes flow direction) and the flow control valve (which controls supply flow rate). This segmentation allows the direction change-over valve to have a smaller, more compact size while the flow control valve handles the flow rate regulation independently.
Solution Approach 2:
The patent extracts the supply flow control function from the direction change-over valve by adding a dedicated flow control valve upstream. This extraction allows the direction change-over valve to focus solely on direction switching with a smaller opening area, while the flow control valve manages the supply flow rate through its own control mechanism.
2Device complexity
If a single spool valve is used to simultaneously perform direction change-over control, supply flow control, and discharge flow control, then the number of parts is reduced, but the relationship between supply flow rate and discharge flow rate is uniquely determined and cannot be changed depending on operating states
Solution Approach 1:
The patent segments the control functions across multiple valves: the flow control valve independently controls supply flow rate, the direction change-over valve independently controls discharge flow rate and direction switching. This functional segmentation enables flexible adaptation to different operating conditions while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent introduces dynamic control capability by allowing independent adjustment of supply and discharge flow rates through separate valve controls. This enables the system to adapt dynamically to varying operating states such as individual vs. combined operations and different load conditions, rather than being locked into a fixed flow rate relationship.
3Ease of operation
If the flow control valve is positioned upstream of the direction change-over valve to control supply flow rate, then independent control of supply and discharge flow rates is achieved, but the opening area of the supply valve passage to the direction change-over valve still affects flow control
Solution Approach 1:
The patent implements control means that monitors and adjusts the opening areas of both the flow control valve and the direction change-over valve to achieve accurate flow rate control. This feedback mechanism compensates for the influence of the supply valve passage opening area, ensuring precise control despite the complex flow path geometry.
Solution Approach 2:
The patent controls the opening areas of valves as adjustable parameters to optimize flow control accuracy. By dynamically adjusting the opening areas of the flow control valve and direction change-over valve based on operating conditions, the system achieves accurate independent control of supply and discharge flow rates despite the presence of the supply valve passage.
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 enables accurate and flexible control of supply and discharge flow rates, preventing the need for large direction change-over valves and improving operational efficiency and accuracy across varying operating conditions.
Implementation Method 1
a supply flow rate from the hydraulic pump to the hydraulic actuator is controlled based on an opening area of the supply valve passage to the direction change-over valve and an opening area of the flow control valve
Implementation Method 2
a discharge flow rate from the hydraulic actuator is controlled based on an opening area of the discharge valve passage from the direction change-over valve
Implementation Method 3
a direction change-over valve having supply/discharge valve passages to/from the hydraulic actuator and changing over supply/discharge directions
Data Source
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AI summary
Problem to be solved: To avoid a large size of a direction change-over valve and enable accurate supply flow control when providing a flow control valve at an upstream side of the direction change-over valve to change the relationship between supply flow rate and discharge flow rate for a hydraulic actuator. Solution: The configuration is to control a supply flow rate to a stick cylinder (8) based on an opening area of the stick's direction change-over valve (25) and stick's flow control valve (28), calculate a target opening area of the stick's flow control valve (28) based on a target supply flow rate from hydraulic pumps A, B to the stick cylinder (8), the opening area of the stick's direction change-over valve (25), and a target differential pressure between hydraulic pump A and a load pressure of stick cylinder (8), and control the stick's flow control valve (28) so as to keep the target opening area calculated.