Hydraulic Spool Valve Flow Control for Dual-Pump Stick Circuits
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Solution Overview
Problem
Hydraulic control systems for work machines like hydraulic shovels require multiple directional switching valves and flow rate control valves, increasing complexity and cost, while lacking flexibility in flow rate control for large flow rate operations.
Innovation Solution
A hydraulic control system with a spool valve directional switching valve that adjusts flow rates based on the operation lever's position, using a combination of main and sub-supply oil passages and flow rate control valves to manage flow rates from multiple hydraulic pumps, allowing separate control of supply and discharge flow rates and reducing the number of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple directional switching valves are used to control supply flow rates from multiple hydraulic pumps to a large flow rate hydraulic actuator, then the flow rate control capability is improved, but the device complexity and number of parts increase
Solution Approach 1:
The patent combines multiple directional switching valves into a single integrated directional switching valve that can control supply flow rates from multiple hydraulic pumps. This single valve integrates the functions of multiple valves, reducing the number of parts while maintaining the capability to control flow rates from different pumps to the large flow rate hydraulic actuator.
Solution Approach 2:
The single directional switching valve is designed to perform multiple functions: it controls supply flow rates from multiple hydraulic pumps, manages flow distribution to different actuators, and provides centralized control for both large flow rate and small flow rate operations. This multi-functional design eliminates the need for separate valves for each function.
2Measurement precision
If multiple flow rate control valves are used to control supply flow rates from hydraulic pumps, then the flow rate control precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent integrates multiple flow rate control functions into a single flow rate control valve. This valve can adjust and control supply flow rates from multiple hydraulic pumps through its internal structure, reducing the number of separate control valves while maintaining precise flow rate control capability for different operating conditions.
Solution Approach 2:
The single flow rate control valve is designed to control flow rates from multiple hydraulic pumps and serve different actuators. It provides universal flow rate control functionality, adjusting supply flow rates based on operational requirements while reducing the total number of control components in the system.
3Reliability
If a center bypass line is used for bleed flow rate control in directional switching valves, then the operability during combined operations is improved, but the design flexibility for priority circuits is reduced
Solution Approach 1:
The patent segments the bypass function from the center bypass line configuration and creates dedicated bypass lines for each hydraulic pump. These bypass lines can be independently controlled and configured, providing flexibility in designing priority circuits while maintaining reliable operability during combined operations of multiple actuators.
Solution Approach 2:
The bypass lines are designed with variable resistance functions that can be dynamically adjusted based on operational requirements. This dynamic control allows the system to adapt priority circuit configurations during different operating conditions, enhancing both operability reliability and design flexibility simultaneously.
Data Source
AI summary
To improve operability and work efficiency while achieving reduction of the number of parts and simplification of circuit structure, in a hydraulic control system equipped with hydraulic actuators whose hydraulic power sources are both the first, second hydraulic pumps. The hydraulic control system is provided with the stick directional switching valve; the main-side, sub-side supply oil passages connecting the hydraulic pumps to the stick directional switching valve; and the stick flow rate control valve which is placed in the sub-side supply oil passage, and controls the supply flow rate from the hydraulic pump when the supply flow rate to the stick cylinder requires the supply flow rates from both the hydraulic pumps, wherein the stick directional switching valve is configured such that the discharge flow rate control is performed in the entire area of the spool stroke, and the supply flow rate control is performed at the first region of the former half of the spool stroke, but not performed at the second region of the latter half of the spool stroke.