Hydraulic Option Circuit Pressure Control for Stable Combined Flow
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Solution Overview
Problem
Existing hydraulic control systems for working machines with option hydraulic actuators require multiple valves, leading to increased parts and costs, and fail to ensure consistent flow rates during combined operations.
Innovation Solution
A hydraulic control system with first and second hydraulic pumps, option merging oil passages, and a control device that includes a pressure compensating valve and variable relief valve to manage pressure and flow rates, ensuring consistent supply to option hydraulic actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple relief valves are disposed in actuator oil passages to control supply pressure for each option hydraulic actuator, then the supply pressure can be controlled according to individual actuator requirements, but the number of parts increases and costs increase
Solution Approach 1:
A single variable relief valve is designed to perform multiple functions by sequentially controlling supply pressure for different option hydraulic actuators (breaker, crusher, grapple) according to their individual pressure requirements, replacing the need for multiple dedicated relief valves
Solution Approach 2:
The variable relief valve dynamically adjusts its relief pressure setting based on which option hydraulic actuator is currently operating, changing from a static pressure control device to a dynamic one that adapts to different working conditions and actuator types
2Adaptability or versatility
If multiple flow rate control valves are provided for first and second hydraulic pumps to supply option hydraulic actuators, then the supply flow rate can be controlled for each pump, but the number of parts increases and costs increase
Solution Approach 1:
A single flow rate control valve is designed to control the supply flow rate from either the first or second hydraulic pump to the option merging oil passage, serving multiple pump sources with one valve instead of requiring separate valves for each pump
3Device complexity
If a shared circuit is used for multiple option hydraulic actuators to save space and reduce parts, then space is saved and number of parts is reduced, but the circuit must respond to control of individual actuators with different pressure and flow rate requirements
Solution Approach 1:
The shared hydraulic circuit incorporates a variable relief valve that dynamically changes its relief pressure setting based on the type of option hydraulic actuator being operated, enabling the circuit to adapt to individual actuator pressure requirements while maintaining a simplified shared structure
Solution Approach 2:
The control device receives information about which option hydraulic actuator is operating and provides feedback control signals to the variable relief valve and flow rate control valve, enabling the shared circuit to automatically adjust to meet the specific pressure and flow rate requirements of the active actuator
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
Reduces the number of parts and costs while ensuring reliable flow rates to option hydraulic actuators, preventing shortages during combined operations.
Implementation Method 1
a pressure compensating valve, disposed on an upstream side of the option control valve, that operates in order to maintain a differential pressure, by introducing an inlet side pressure and an outlet side pressure of the option control valve, between the introduced inlet side pressure and outlet side pressure at a predetermined pressure
Implementation Method 2
lowering a pressure of the signal pressure introduction oil passage down to a relief setting pressure by the variable relief valve and introducing the pressure to the pressure compensating valve
Data Source
AI summary
To put new thought to a control method, and to obtain good operability, upon providing a control circuit for option hydraulic actuator in a hydraulic circuit for a working machine. There is provided an option merging oil passage that allows the discharge oil of the first, second hydraulic pumps to be merged thereinto, and the option merging oil passage is provided with an option control valve and a compensator valve, and is configured such that a variable relief valve is connected to a signal pressure introduction oil passage connected to the compensator valve, a supply pressure to an option hydraulic actuator can be variably controlled by changing a relief setting pressure of the variable relief valve; on the other hand, distributed flow rate computation with respect to the other hydraulic actuators, opening area control of the option control valve, the other hydraulic actuators control valves, and discharge pressure control of the first, second hydraulic pumps are optimized.