Relief Pressure Control for Hydraulic Work Machines
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Solution Overview
Problem
Conventional relief pressure control systems for hydraulic working machines with variable solenoid relief valves fail to accurately adjust relief pressure without actuating the working equipment, leading to surge pressures and fluctuations, and are limited to specific equipment types like crushers or breakers.
Innovation Solution
A method that uses stop valves to maintain a closed line between the directional control valve and hydraulic actuator, allowing for pressure oil delivery and detection without actuating the equipment, enabling precise adjustment of relief pressure through a pressure sensor and controller, applicable to various hydraulic working machines with variable solenoid relief valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the working equipment is actuated to adjust relief pressure, then the relief pressure can be adjusted according to actual working conditions, but surge pressure arises and pressure fluctuations occur making accurate adjustment impossible
Solution Approach 1:
The system performs preliminary action by detecting circuit pressure and comparing it with required pressure before actual relief pressure adjustment. The controller calculates the difference and determines necessary adjustment in advance, then actuates the variable solenoid relief valve to achieve the target pressure, avoiding surge pressure from equipment actuation.
Solution Approach 2:
The variable solenoid relief valve serves as an intermediary device between the hydraulic pump and the working equipment. It directly adjusts relief pressure through electrical control signals from the controller, eliminating the need to actuate working equipment for pressure adjustment and thus avoiding surge pressure and fluctuations.
2Ease of operation
If the conventional relief pressure control system is used, then the system can display and instruct start of control, but it cannot realize control without actuating the working equipment
Solution Approach 1:
The relief pressure control system performs self-service by automatically detecting circuit pressure through the pressure sensor, comparing it with required pressure, calculating the difference, and controlling the variable solenoid relief valve to adjust pressure. This eliminates the need to actuate working equipment and enables control to be performed independently.
Solution Approach 2:
The system implements feedback control by continuously detecting circuit pressure with the pressure sensor, comparing it with the required pressure for the working equipment, and using the controller to adjust the variable solenoid relief valve based on the pressure difference. This closed-loop feedback enables accurate relief pressure control without actuating working equipment.
3Device complexity
If the control method is limited to crushers or breakers, then the system design is simplified, but it cannot be applied to other types of working equipment
Solution Approach 1:
The relief pressure control system achieves universality by using a generic control architecture that can be applied to various types of working equipment including crushers, breakers, booms, arms, and rotary attachments. The system detects circuit pressure and controls the variable solenoid relief valve based on required pressure for any equipment type, making it adaptable across different hydraulic working machines without requiring equipment-specific design modifications.
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
Enables accurate adjustment of relief pressure without surge pressures or fluctuations, allowing for high-precision control regardless of equipment actuation, and extends the method's applicability to diverse hydraulic working machines beyond crushers or breakers.
Implementation Method 1
a pressure sensor for detecting a circuit pressure
Implementation Method 2
a variable solenoid relief valve arranged between the directional control valve and the hydraulic actuator to specify a maximum circuit pressure
Data Source
Figure 1
Figure 2
Figure 3
AI summary
[Problem] To provide a relief pressure control system for a hydraulic working machine, which can realize control of a relief pressure of a variable solenoid relief valve without actuation of working equipment. [Solution] A relief pressure control system is provided with a controller (13) for outputting, responsive to an adjustment signal outputted from a dial switch (12), a control signal to control a relief pressure of a variable solenoid relief valve (10a or10b), a display unit (14) for displaying, responsive to display signals outputted from the controller (13), a relationship between a circuit pressure outputted from a pressure sensor (11) and a pressure required by a hydraulic cylinder (1), and a control device (6) constituting a start instruction unit for instructing a start of control of the variable solenoid relief valve (10a or10b). Stop valves (15a, 15b) are arranged sections of main lines (9a, 9b), which communicate a directional control valve (4) and the hydraulic cylinder (1) with each other, to open or close the section. The sections are located between positions on the main lines, where the variable solenoid relief valves (10a,10b) are connected to the main lines, respectively, and the hydraulic cylinder (1).