Komatsu Corporation

Yukio Shoji

Nobumi Yoshida

Yuichi Yamamoto

Masato Kageyama

It is an object of the present invention to provide a filter for trapping foreign matter in which a filtration element can trap foreign matter that is admixed to a fluid present inside the filter with good reliability and a comparatively high trapping ratio. Hydraulic oil that has flown from an opening portion into a guide space of a first flow path guide is guided downward by the first flow path guide and directed toward a second flow path guide. As a result, the oil passes through a very narrow gap, that is, a gap with a cross sectional area of the flow path narrowed so as to increase the flow velocity of the hydraulic oil, a rising flow of the hydraulic oil is formed, and this flow is spouted up by the second flow path guide and guided by the first flow path guide toward a filter element. Foreign matter admixed to the hydraulic oil rises with good intensity together with the hydraulic oil and is moved by the hydraulic oil toward the filter element. Therefore, foreign matter can be trapped by the filter element with good reliability and a comparative high trapping ratio.

Filter for trapping foreign matter

A plurality of Hall ICsA,B are disposed around a magnetic rodthat is movable along a central axis. The Hall ICs are disposed in different positions in terms of both a straight line distance coordinate in the direction of the central axis and a rotational angle coordinate around the central axis. The amount of displacement of the magnetic rodis calculated based on the average of output signals from the Hall ICs. Errors in the output signals due to a shift and tilt of the magnetic rod are detected and calibration of the measurement method is carried out.

Displacement sensor

A disclosed device eliminates an error in a displacement amount measured value caused by changes over time in a characteristic of a displacement sensor, and can always maintain high accuracy of measurement. When a hydraulic valve, to which the displacement sensor is mounted, is positioned at predetermined positions, output signals from the displacement sensor are acquired as sample values. On the basis of the acquired sample values, a trend of changes over time in the characteristic of the displacement sensor is computed. Settings of a conversion table, which is used for displacement amount computation, are corrected in a direction along the computed trend of changes.

Displacement amount measuring device

In a hydraulic machine, hydraulic pump failure is detected and the pump lifespan is estimated before the pump failure occurs. The discharge pressure, oil temperature, and drain filter differential pressureare measured, a correlative relationshipbetween the filter differential pressure and the discharge pressure is determined, and a representative filter differential pressureis calculated from this correlative relationship. Using an oil temperature-differential pressure correlation function, the representative differential pressure valueis corrected so that the variable componentcaused by the oil temperatureis eliminated therefrom. The long-term trend and the short-term trend of the increase over time of the corrected differential pressure is calculated. A pump failure is predicted or the pump lifespan is estimated based on the degree of deviation between the long-term trend and the short-term trend.

Hydraulic machine, system for monitoring health of hydraulic machine, and method thereof

In a displacement sensor (), a shaft () of a movable member () comprises a tubular part () having an opening () at one end. A rod-form permanent is inserted into the tubular part () through the opening () . A spacer () is fitted over a narrow portion of the rod-form magnet (). The thickest portion of the magnet () and the spacer () contact the side wall of the tubular part () tightly, so that the magnet () is disposed coaxially with the tubular part (). A stopper () is formed on the opening () of the tubular part (), so that the magnet () does not move axially. Therefore, the magnet () is mounted in a prescribed position in a movable member () with a high degree of accuracy.

Growing community of inventors

Tochigi, Japan

Yukio Shoji