JPH05105395A - Abnormality detecting device of outrigger length sensor in crane - Google Patents

Abstract

PURPOSE:To surely detect abnormality of an outrigger length sensor. CONSTITUTION:An abnormality detecting device is constructed in such a way as inputting a signal from an outrigger operation sensor 1 and a signal from an outrigger length sensor 2 into an abnormality discriminating means 3 to compare them mutually, and deciding that the outrigger length sensor 2 is abnormal when these both sensor signals do not correspond to each other, and displaying it by a displaying means 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outrigger length sensor abnormality detecting device for detecting an abnormality in an outrigger length sensor in a crane having an outrigger.

[0002]

2. Description of the Related Art A crane is equipped with an overload prevention device, which detects the operating state of the crane and the load state based on it, and displays it on a display unit, and when a danger of overload occurs. It is configured to issue an overload alarm and perform a safe operation such as automatically stopping the operation of the crane toward the dangerous side.

Here, since the hanging ability greatly changes depending on the overhanging state of each outrigger (in-situ extension, intermediate extension, full extension), conventionally, the length of each outrigger is detected by a sensor to check the outrigger extension state. , Which is used as an element for overload monitoring.

As the outrigger length sensor, there is used one having a structure for transmitting the expansion / contraction motion of the outrigger to a potentiometer via a rope, a pulse encoder or the like.

[0005]

This outrigger length sensor is provided in the outrigger where dirt or water easily flows in, and maintenance may not be performed sufficiently.

However, conventionally, since there is no means for detecting the abnormality of the outrigger length sensor, there is a possibility that the intended purpose of monitoring the outrigger extension state cannot be sufficiently achieved.

As a general abnormality detecting means for the sensor,
Fixed limitation on voltage signal from sensor (for example, 2V to 8V limitation when the entire voltage range is 0-12V)
There is a known means for determining an abnormality when a signal outside this limit value is input.

In this means, however, in the case of a potentiometer type sensor, for example, the rope is caught in piping or the like and sags when the outrigger is contracted, and the signal itself is in the normal range but the signal value does not change even if the outrigger is operated. Therefore, it is difficult to accurately detect the abnormality.

Therefore, the present invention provides an abnormality detection device for an outrigger length sensor in a crane, which can reliably detect an abnormality in the outrigger length sensor.

[0010]

SUMMARY OF THE INVENTION The present invention provides a crane having an outrigger, an outrigger length sensor for detecting the length of the outrigger, and an outrigger operating device for extending and retracting the outrigger to operate the outrigger. An outrigger operation sensor that detects that the device has been operated, an abnormality determination means that outputs an abnormality signal when signals from the outrigger operation sensor and the outrigger length sensor are input, and these two sensor signals do not correspond, and Display means for displaying an abnormality based on the abnormality signal from the abnormality determining means is provided.

[0011]

According to the above construction, when both sensor signals do not correspond to each other, that is, when the outrigger length signal which is a reaction of the outrigger is not changed even though the outrigger is operated, or the outrigger is not operated, the outrigger is operated. The outrigger length sensor is determined to be abnormal when the length signal changes.

Therefore, there is no erroneous judgment as in the case of judging the abnormality of the outrigger length sensor only based on the magnitude of the sensor signal, and the sensor abnormality can be surely detected.

[0013]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a block configuration of this apparatus.

As an outrigger operation device, an operation signal (outrigger operation signal) of an outrigger operation switch 1 for controlling an outrigger cylinder overhang and a retracting operation from a driver's seat.
Is sent to the control unit for the outrigger cylinder and also sent to the abnormality determination unit 3 at the same time.
The abnormality determination unit 3 matches the outrigger length signal fetched from the outrigger length sensor 2 with each other.

In the abnormality discriminating section 3, it is determined whether or not the outrigger length signal is changed when the outrigger operation signal is input, and whether or not the outrigger length signal is changed when the outrigger operation signal is not input. The normality / abnormality of the outrigger length sensor 2 is discriminated by the, and when the abnormality is discriminated, the display unit 4 including one or a plurality of indicators such as a lamp and a buzzer is activated.

The operation of this point will be described in more detail with reference to the flow chart of FIG. 2. The flow starts when the power supply of the overload prevention device is turned on, and it is first determined in step S1 whether or not there is an outrigger operation signal.

Here, if YES, that is, if it is determined that there is an outrigger operation signal, it is next determined whether or not the signal from the outrigger length sensor 2 has changed (step S2). If the outrigger length sensor 2 responds normally to the outrigger operation, it is determined that there is no abnormality (step S3).

Further, if NO in step S1, that is, if there is no outrigger operation signal, it is continuously determined in step S4 whether or not the sensor signal has changed. If there is no change, the process returns to step S1 to prepare for outrigger operation.

On the other hand, when it is determined in step S2 that there is no change in the sensor signal, and when it is determined in step S4 that there is a change in the sensor signal, it is determined that the reaction is not normal, and the sensor abnormality is determined (step S5) and displayed. The sensor abnormality is displayed by the unit 4 (step S
6).

As described above, when the sensor signal does not change even when the outrigger is operated, when the sensor signal changes even when the outrigger is not operated, that is, when the outrigger operation does not correspond to the sensor signal. Since it is judged that the sensor is abnormal, there is no erroneous judgment as in the case of judging only by the magnitude of the sensor signal, and the sensor abnormality is reliably detected.

By the way, in a crane that uses a remote control valve as an outrigger operation device, a switch that operates in conjunction with a lever operation of the remote control valve, an optical sensor that detects a lever position, a limit switch, or the like is used as an outrigger operation sensor. You can

[0023]

As described above, according to the present invention, the signal from the outrigger operation sensor and the signal from the outrigger length sensor are input to the abnormality determining means and associated with each other, and when these sensor signals do not correspond to each other. Since the outrigger length sensor is judged to be abnormal and the abnormality is displayed by the display means, there is no erroneous judgment as in the case of judging abnormality of the outrigger length sensor only by the magnitude of the sensor signal, and the sensor abnormality is detected. It can be reliably detected.

Therefore, it is possible to prevent the occurrence of an unexpected situation due to a sensor abnormality such as the outrigger being set to the extended state even when it is not extended, and the reliability of the overload prevention device is improved to improve the safety of work. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flow chart for explaining the operation of the embodiment.

[Explanation of symbols]

1 Outrigger operation switch as an outrigger operation sensor 2 Outrigger length sensor 3 Abnormality determination section (abnormality determination means) 4 Display section (display means)

Claims (1)

[Claims] 1. A crane provided with an outrigger, an outrigger length sensor for detecting a length of the outrigger, and an outrigger operating device for extending and retracting the outrigger, the operation of the outrigger operating device being detected. An outrigger operation sensor, an abnormality determining means for outputting a signal when the signals from the outrigger operation sensor and the outrigger length sensor are not input and the two sensor signals do not correspond to each other, and the abnormality signal from the abnormality determining means. An abnormality detection device for an outrigger length sensor in a crane, characterized in that display means for performing abnormality display based on the abnormality detection device is provided.