Hydraulic Pump Deterioration Detection via Pressure and Command Current

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Solution Overview

Problem

Existing methods for detecting performance deterioration in hydraulic pumps, such as measuring drain flow rates, are prone to measurement inaccuracies due to the slight flow rates involved, making it difficult to detect minute decreases in delivery flow rates.

Innovation Solution

A hydraulic pump performance deterioration detection system that uses a variable displacement hydraulic pump, a regulator, a switching valve, control circuitry, and a pressure sensor to determine performance deterioration based on the command current and delivery pressure without relying on flowmeter measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a flowmeter is used to measure drain flow rate to detect hydraulic pump performance deterioration, then measurement capability is provided, but measurement precision deteriorates due to the slight flow rate being readily affected by measurement precision limitations

Engineering Contradiction:

Improvedrain flow rate measurement precisionVSAvoidperformance deterioration detection reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces a switching valve as an intermediary component to block the drain flow path during measurement. This allows the system to measure delivery pressure upstream of the valve while the valve prevents actual fluid flow, enabling accurate detection of pump performance deterioration through pressure changes rather than direct flow measurement. The switching valve mediates between the need to measure slight flow rates and the limitation of flowmeter precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Difficulty of detecting and measuring

If drain flow rate measurement is used to detect performance deterioration, then detection capability is provided, but detection precision worsens making it difficult to detect minute decreases in delivery flow rate

Engineering Contradiction:

Improveperformance deterioration detection capabilityVSAvoiddelivery flow rate decrease detection precision

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent changes the measurement parameter from drain flow rate to delivery pressure. By measuring pressure upstream of the switching valve while the valve is closed, the system can detect minute decreases in delivery flow rate caused by pump wear with much higher precision. The pressure parameter is more sensitive to small changes in pump performance than direct flow rate measurement of the small drain flow.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If a flowmeter is installed to measure drain flow rate, then measurement function is provided, but device complexity increases

Engineering Contradiction:

Improveflow rate measurement capabilityVSAvoidmeasurement system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The switching valve serves as an intermediary that enables pressure-based measurement instead of requiring a flowmeter. By blocking the drain path and measuring upstream pressure, the system achieves accurate pump performance detection without the complexity of installing and calibrating a flowmeter for slight flow rates. The valve simplifies the measurement system while maintaining or improving detection capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 detection of hydraulic pump performance deterioration without using a flowmeter, providing higher precision than traditional methods and allowing for detection of internal leakage and other slight leakages in the hydraulic circuit.

Implementation Method 1

a pressure sensor that measures a delivery pressure of the hydraulic pump at a position upstream of the switching valve

Methodology Applied

Scientific EffectPressure measurement:

Implementation Method 2

a regulator that changes a displacement of the hydraulic pump in accordance with a command current

Methodology Applied

Scientific EffectElectromagnetic actuation:

Data Source

PatentUS12313097B2Hydraulic pump performance deterioration detection system

Publication Date: 2025.05.27 KAWASAKI JUKOGYO KK

AI summary

A hydraulic pump performance deterioration detection system according to one embodiment includes: a variable displacement hydraulic pump that supplies a hydraulic liquid to a hydraulic actuator to move the hydraulic actuator; a regulator that changes a displacement of the hydraulic pump in accordance with a command current; and control circuitry that feeds the command current to the regulator. When the hydraulic actuator is not moving, in a state where a switching valve located on a passage through which the hydraulic liquid delivered from the hydraulic pump flows is switched to a closed position and the hydraulic pump is being driven at a predetermined rotation speed, the control circuitry determines whether or not performance of the hydraulic pump has deteriorated based on a current value of the command current and a delivery pressure of the hydraulic pump measured by a pressure sensor.