Hydraulic Safety Device Using High-Pressure Selection Circuit
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Solution Overview
Problem
The existing safety devices for hydraulic working machines require multiple pressure sensors to detect pilot pressure, leading to increased costs and complexity.
Innovation Solution
A safety device that uses a high-pressure selection circuit and pressure detectors to determine abnormality in electromagnetic proportional valves based on calculated and detected control pressures, reducing the number of pressure sensors needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple pressure sensors are used to detect pilot pressure applied to the control valve, then the reliability of abnormality detection is improved, but the cost and device complexity increase
Solution Approach 1:
The patent merges the detection functions for multiple control pressures into a single pressure sensor by using a high-pressure selection circuit. This circuit selects and outputs the higher pressure between the first and second control pressures, allowing one pressure sensor to monitor both control pressure lines simultaneously, thereby reducing sensor quantity while maintaining detection reliability
Solution Approach 2:
The high-pressure selection circuit acts as an intermediary between the multiple control pressure lines and the single pressure sensor. It mediates the pressure signals by selecting the higher pressure value, enabling the pressure sensor to indirectly monitor all control pressure lines through this intermediate selection mechanism
2Measurement precision
If multiple pressure sensors are deployed to monitor each control pressure line, then the measurement precision is improved, but the manufacturing cost increases
Solution Approach 1:
The patent combines multiple pressure measurement functions into a single pressure sensor through the high-pressure selection circuit. By selecting the higher pressure value, the system maintains precise monitoring of control pressure variations while reducing the number of sensors required, thereby lowering manufacturing costs
Solution Approach 2:
The system uses a single pressure sensor to copy or represent the pressure state of multiple control pressure lines. The high-pressure selection circuit ensures that the single sensor captures the critical pressure information (the higher pressure) that would otherwise require multiple sensors to monitor simultaneously
Data Source
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AI summary
There are provided: control valves 22 - 24 that control flow of pressure oil from the hydraulic source 21 to the hydraulic actuators 15 - 17; electric lever devices 51 - 53 that output electrical operation signals v51 - v53 in correspondence to lever operation; electromagnetic proportional valves 25 - 30 through which control pressures for controlling the control valves 22-24 are output; a pressure calculating unit 50 that calculates control pressures P25 - P30 in correspondence to the operation signals V51 - v53; a control unit 50 that controls the electromagnetic proportional valves 25 - 30 so that control pressures to be output from the electromagnetic proportional valves 25 -30 become the control pressures P25 - P30 that have been calculated; a high-pressure selection circuit 41 - 44 that selects a higher pressure between control pressures that have been output from the electromagnetic proportional valves 25 - 30; pressure detectors 45 and 46 that detect a control pressure selected by the high-pressure selection circuit 41 - 44; an abnormality determination unit 50 that determines an abnormality in the electromagnetic proportional valves 25 - 30 based upon the control pressure detected by the pressure detectors 45 and 46 and the control pressure calculated by the pressure calculating unit; and an inhibiting device 47 and 48 that prohibits control of the control valves 22 - 24 when it is determined that an abnormality has occurred in the electromagnetic proportional valves 25 - 30.