Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle diagnosis or maintenance indication
Reexamination Certificate
1998-10-05
2001-01-16
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle diagnosis or maintenance indication
C701S050000
Reexamination Certificate
active
06175788
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a failure diagnosis method for industrial vehicles, such as dump trucks, and a device therefor.
BACKGROUND ART
In industrial vehicles, such as dump trucks, a reduction in the down time at the time of a failure is important; therefore, several conventional failure diagnosis apparatuses have been proposed. These failure diagnosis apparatuses are to diagnose which device or portion of a device fails when the vehicle develops any trouble. For example, they diagnose one by one whether or not operations and functions of respective sensors, respective actuators, respective controllers, and the like, are normal; and when an error is detected they use an indicator to inform an operator of the name of a failed part and a code number indicative of the kind of abnormality. Since the failed part with an error indication can be replaced or repaired, the recovery can be completed within a short period of time.
Such conventional failure diagnosis apparatuses may, however, cause a problem in that when a failure occurs intermittently without showing a continuous abnormal state, a true cause of the failure cannot be detected. In such a case, a cause of the failure or the failed part is guessed from the contents of the failure, and some recovery steps, such as a replacement of an associated part or sensor, are taken to recover from the failure. However, if the recovery steps are irrelevant, the part replacement must be repeated many times, and it takes a long time to diagnose a true cause of the failure. Such an extended idle time reduces the efficiency of the failure correction, causing a problem in that the down time cannot be reduced.
Further, recently there has been a strong demand to develop a failure diagnosis apparatus for use not only to correct a failure when an error occurs, but also to predict a failure before an error occurs, so as to prevent the generation of the failure and hence to reduce the down time. Such a failure diagnosis apparatus periodically diagnoses the states of respective devices, such as an engine, a transmission, axles, suspensions, hydro-pneumatic systems, and a brake, stores the diagnostic data as hysteresis, and predicts an occurrence of a failure on the basis of the hysteresis. In other words, it performs a so-called trend analysis. Even when a failure has occurred, the failure diagnosis apparatus can refer to the hysteresis data to diagnose a true cause of the failure.
However, the specific work of such periodic diagnoses requires an interruption of vehicle operations. This causes an undesirable reduction in the operating ratio of the vehicle, and hence is a hindrance to production efficiency. Therefore, it is desirable to provide a diagnosis method which is capable of being carried out without any interruption of vehicle operations. In this diagnosis method, the diagnostic data to be stored as hysteresis must be pertinent data which is capable of diagnosing an exact failure portion, i.e., capable of representing a state of a trend toward the generation of a failure.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of such conventional problems, and an object thereof is to provide a failure diagnosis method for a dump truck and a device therefor, which is capable of preventing the generation of a failure and of diagnosing a true cause of failure in a short period of time.
In a first aspect of the present invention, there is provided a failure diagnosis method for a dump truck having a diagnosis device for diagnosing an operation and function of each device, such as an engine, a transmission, respective axles, respective suspensions, hydro-pneumatic systems or a brake, while a vessel body descends after the evacuation of a load from the vessel body, wherein an operation and function of at least one of the devices, such as the engine at a predetermined engine rotational speed, the transmission, the respective axles, the respective suspensions, the hydro-pneumatic systems, and the brake, are diagnosed during the descent of the vessel body.
According to this method, hydraulic circuit components, such as a hydraulic pump, are in a predetermined steady state while the vessel body descends after the completion of evacuating loaded material. Since a state of each device, such as the engine, the transmission, the axles, the suspensions, the hydraulic systems or the brake, is measured in the steady state, the diagnosis can always be made under identical conditions. Thus, the diagnostic data can represent an accurate state of the trend for each device. Therefore, it is possible to store the diagnostic data as hysteresis so as to diagnose the exact element which has failed. Further, since the diagnosis method does not require an interruption of normal vehicle operations, the production efficiency can be maintained without any reduction in the operating ratio of the vehicle.
In a second aspect of the present invention, there is provided a failure diagnosis device for a dump truck provided with a vessel body having a capacity for loading and evacuating material, the failure diagnosis device including state detecting means for detecting the temperature, the pressure, and the position of a device, such as an engine, a transmission, respective axles, respective suspensions, hydro-pneumatic systems, or a brake, such that an operation and function of each device can be diagnosed. The failure diagnosis device comprises body operating means for giving a command to raise or lower the vessel body, a direction switching valve for receiving the command from the body operating means to lower the vessel body, and a self-diagnosis control device for using the state detecting means to detect a state of at least one of the respective devices, out of the engine at a predetermined engine rotational speed, the transmission, the respective axles, the respective suspensions, the hydro-pneumatic systems, and the brake, when the body operating means is at a predetermined operative position, for storing a detected value as hysteresis data, and for comparing a magnitude of the detected value and a rate of change with reference values on the basis of the hysteresis data when carrying out a failure diagnosis of an operation and function of a respective device.
According to this device, when an operator sets the body operating means at a predetermined operative position (e.g., a float position or descending position) at the time of evacuation of a load from the vessel body, the direction switching valve, which is operative to control the raising and lowering of the vessel body, is switched to a position corresponding to the operative position to contract the hoist cylinders so that the vessel body will descend. At this time, since a hydraulic pump becomes a constant loaded state, the respective hydraulic components of a hydraulic circuit of the dump truck are in a steady, normal state. In this state, signals from the state detecting means for detecting the temperature, the pressure, and the position of each device, such as the engine, the transmission, the respective axles, the respective suspensions, the hydro-pneumatic systems, or the brake, are always measured, under identical conditions; and the measured data are inputted to the self-diagnosis control device. Thus, the diagnostic data, determined on the basis of the detected value from the state detecting means, can represent an accurate state of the trend for the respective device. The diagnostic data are stored as hysteresis, and a magnitude of the detected value and a rate of change thereof are compared with reference values on the basis of the hysteresis data. This makes it possible to diagnose the exact element which has failed. Further, since the diagnosis is carried out during a descent of the vessel body, there is no need to interrupt normal vehicle operations during the diagnosis, thereby maintaining the production efficiency without any reduction in the operating ratio of the vehicle.
In a third aspect of the present invention, there is provided a failure diagno
Hasegawa Nobuki
Sugano Yukio
Watanabe Genichirou
Komatsu Ltd.
Sidley & Austin
Zanelli Michael J.
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