Hydraulic Pressure Control Device Abnormality Detection

Solution Overview

Problem

Conventional hydraulic units face challenges in detecting abnormalities, such as pump failure or leakage, in the hydraulic circuit due to the need for multiple sensors, which increases costs and reduces detection efficiency.

Innovation Solution

A hydraulic pressure control device that includes a hydraulic sensor between the pump and a load, a speed command arithmetic unit, a torque command unit, and a hydraulic pressure abnormality detector using primary delay filter processing to detect abnormalities without increasing the number of sensors, allowing for the detection of pump and circuit failures, including leakage, by comparing the speed command value with pre-set thresholds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple hydraulic sensors are installed to detect pump failure and circuit leakage, then detection precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improveabnormality detection precisionVSAvoidnumber of sensors

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The motor current detector serves multiple functions: it monitors motor operation status and simultaneously detects hydraulic circuit abnormalities (pump failure, leakage) by analyzing current variations. This single device performs what would traditionally require multiple specialized sensors, reducing system complexity while maintaining detection precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the motor's own current characteristics as an indicator of hydraulic system health. By analyzing variations in motor current that occur when hydraulic abnormalities affect motor load, the system enables self-diagnosis without requiring external sensing devices in the hydraulic circuit.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If multiple hydraulic sensors are installed to detect pump failure and circuit leakage, then detection precision is improved, but cost increases

Engineering Contradiction:

Improveabnormality detection precisionVSAvoidsensor quantity

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The motor current detector serves multiple functions: it monitors motor operation status and simultaneously detects hydraulic circuit abnormalities (pump failure, leakage) by analyzing current variations. This single device performs what would traditionally require multiple specialized sensors, reducing system complexity while maintaining detection precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the motor's own current characteristics as an indicator of hydraulic system health. By analyzing variations in motor current that occur when hydraulic abnormalities affect motor load, the system enables self-diagnosis without requiring external sensing devices in the hydraulic circuit.

Inventive Principle:

Principle #25Self-service

3Reliability

If hydraulic sensors are installed at multiple circuit points, then detection coverage is improved, but ease of operation deteriorates due to complex sensor management

Engineering Contradiction:

Improvedetection coverageVSAvoidsensor management complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The detection function is extracted from the hydraulic circuit and relocated to the motor control system. By removing hydraulic sensors from the hydraulic circuit and using the existing motor current detection infrastructure, the system maintains comprehensive detection coverage while eliminating the operational complexity of managing multiple hydraulic sensors.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS10371139B2Hydraulic pressure control device

Publication Date: 2019.08.06 OKUMA CORP

AI summary

A hydraulic pressure control device comprising: a hydraulic sensor provided between a hydraulic pump and a load; a speed command arithmetic unit configured to output a speed command value Vc based on a difference between a hydraulic pressure detection value Pd from the hydraulic sensor and a hydraulic pressure command value Pc; a torque command value arithmetic unit configured to calculate a torque command value Tc based on a difference between a speed detection value Vd of a motor and the speed command value Vc; a current controller configured to control current of the motor based on the torque command value Tc; and a hydraulic pressure abnormality detector configured to detect whether a hydraulic circuit has abnormality based on the speed command value Vc and an operating condition of the load of the hydraulic circuit commanded from an upper-level control device.