Hydraulic Pump Abnormality Detection via Volumetric Transfer Efficiency
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Solution Overview
Problem
Conventional methods for detecting abnormality in hydraulic pumps, such as malfunction and wear, are either inaccurate due to reliance on heuristic drain flow rate measurements or costly due to the need for expensive flow rate sensors, making them impractical for economic implementation in work machines.
Innovation Solution
A work machine equipped with an actuator, hydraulic pumps, a merge circuit, and a controller that calculates volumetric transfer efficiency to determine abnormality, eliminating the need for additional flow rate sensors by using the speed of the actuator and the discharge flow rate of the hydraulic pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drain flow rate measurement is used to estimate hydraulic pump wear, then abnormality detection is possible, but measurement precision is insufficient and cannot detect control equipment malfunctions
Solution Approach 1:
The patent replaces the mechanical/heuristic drain flow rate measurement method with an electronic control system that calculates volumetric transfer efficiency using electrical signals from sensors and controller computations. This substitution enables precise measurement of both actuator speed and pump discharge flow rate, allowing accurate detection of both wear and control equipment malfunctions.
Solution Approach 2:
The patent introduces volumetric transfer efficiency as an intermediary parameter that mediates between the measurable quantities (actuator speed, pump discharge flow rate) and the target assessment (hydraulic pump condition). This intermediary enables comprehensive evaluation of both mechanical wear and control system abnormalities through a unified metric.
2Measurement precision
If expensive flow rate sensors are installed to accurately measure hydraulic oil flow rate, then measurement precision improves, but equipment cost increases making it impractical
Solution Approach 1:
The patent makes existing sensors serve multiple functions: the actuator speed sensor simultaneously provides speed measurement for operation control and flow rate data for pump condition monitoring. The pump discharge flow rate is derived from controller calculations using existing control parameters rather than requiring dedicated flow sensors. This multi-functionality eliminates expensive specialized sensors while maintaining measurement precision.
Solution Approach 2:
The system uses its own existing sensors and control computations to provide the measurement functionality that would otherwise require expensive additional equipment. The actuator speed sensor and controller calculations serve the dual purpose of control operation and pump condition monitoring, making the system self-sufficient.
3Reliability
If periodic replacement of hydraulic pumps is performed to maintain performance, then reliability is maintained, but productivity decreases due to unnecessary replacements and costs increase
Solution Approach 1:
The patent implements continuous feedback monitoring of volumetric transfer efficiency to track the actual condition of hydraulic pumps in real-time. This feedback enables condition-based maintenance decisions, allowing replacements to be performed only when actually needed rather than following fixed schedules, thereby maintaining reliability while minimizing productivity loss from unnecessary replacements.
Data Source
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AI summary
A work machine that can detect abnormality such as a malfunction and wear and tear of each of hydraulic pumps including control equipment with high precision and that can reduce equipment cost is provided. A controller 9 according to the present invention includes a volumetric-transfer-efficiency-calculating section 94 that calculates a volumetric transfer efficiency ηC representing a transfer efficiency of hydraulic oil between a hydraulic cylinder 11 and hydraulic pumps 21 to 23 on the basis of a target discharge flow rate calculated by a target-discharge-flow-rate-calculating section 932 and the speed of the hydraulic cylinder 11 that is detected by a speed sensor 28, and an abnormality decision section 95 that decides whether any one of the hydraulic pumps 21 to 23 is abnormal on the basis of the volumetric transfer efficiency ηc calculated by the volumetric-transfer-efficiency-calculating section 94.