JPH03223095A - Safety alarm system for crane - Google Patents

Abstract

PURPOSE:To alarm an abnormality of the moment of a boom accurately by forming a system so as to generate an alarm only when the working pressure of the boom exceeds a set value for a certain time. CONSTITUTION:A differential pressure circuit 12 outputs the differential pressure signal corresponding to the differential pressure of pressure sensors 10, 11 for detecting the high pressure and the low pressure of an outrigger as a boom driving cylinder, and a comparator 13 compares the output signal of the differential pressure circuit 12 and a set voltage VR, and when the output signal of the differential pressure circuit 12 exceeds the set voltage VR, the comparator 13 generates the pulse signal having a pulse duration corresponding to the cylinder differential pressure. The output of the comparator 13 is input to one input terminal of an AND gate 15 and a pulse generator 14, and the pulse generator 14 and the AND gate 15 measure a pulse duration of the pulse signal of the output from the comparator 13, and only when the measured value exceeds the set value, the alarm signal is generated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a safety warning system for cranes, and is particularly suitable for preventing overturning accidents caused by the boom moment of cranes used in construction machinery. It's about systems.

[Conventional technology]

Generally, in a crane used for construction machinery, the outputs of a tension sensor 51, an angle sensor 52, a position sensor 53, and a pressure sensor 54 are compared with set values in a comparison circuit 55, as shown in FIG. However, a safety alarm system is employed that drives the transistor 56 to generate an alarm signal or automatically stops the machine when the signal from any sensor exceeds a set value.

[Problem to be solved by the invention]

However, in the conventional system, as shown in FIG.
The pressure at 58 is detected by a pressure sensor 54, and based on this signal, the pump pressure is increased to the pressure when suspended with an object, that is, to the equilibrium pressure.

Therefore, when lifting an object with the crane 57, the operating pressure of the gun is different depending on whether it is lifted slowly or slowly.

Therefore, if the pressure difference between the equilibrium pressure and the equilibrium pressure is ΔF, if the operating pressure changes as shown in FIG. As shown in Figure 8, even if the boom moment does not show an abnormal value, if the operating pressure value instantaneously exceeds the set value, the detection signal at this time may cause a warning signal to be erroneously output. There is.

An object of the present invention is to provide a crane safety alarm system that can reliably detect an abnormal value of boom moment and issue an alarm.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a differential pressure detecting means for detecting a cylinder differential pressure proportional to the moment of the boom among the driving pressure of the boom driving cylinder, and a cylinder differential pressure output from the differential pressure detecting means. Pulse generating means generates a pulse signal with a pulse width corresponding to the cylinder differential pressure when a set value is exceeded, and a pulse generator that measures the pulse width of the pulse signal and generates an alarm signal when the measured value exceeds the set value. This is a crane safety alarm system comprising an alarm signal generating means for generating an alarm signal.

[Effect]

By employing the above-mentioned means, the present invention detects the cylinder differential pressure proportional to the boom moment out of the driving pressure of the boom driving cylinder, and when this cylinder differential pressure exceeds a set value, the cylinder differential pressure is detected. Since a pulse signal with a pulse width corresponding to the pulse width is generated, and an alarm signal is generated only when the pulse width of this pulse signal exceeds the set value, even if the boom moment moment instantly exceeds the set value, it will not cause a false alarm. An alarm signal is not generated when the boom moment exceeds a set value for a certain period of time, and an alarm signal is issued only when the boom moment exceeds a set value for a certain period of time, making it possible to reliably warn of an abnormality in the boom moment.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, the crane safety alarm system includes a pressure sensor 1O111, a differential pressure circuit 12, a comparator 13, a pulse generator 14, an AND gate 15, a comparison circuit 16, a transistor 17, an alarm generator 18, a tension sensor 19, and an angle sensor 20. , and a position sensor 21.

As shown in FIG. 2, the repressure sensor 10.11 is installed at the top and bottom of the outrigger 24, which serves as a boom driving cylinder for driving the boom 23 of the crane 22, in order to detect the pressure above and below the cylinder. They are arranged separately.

Then, the detection signal of each sensor 10.11 is transmitted to the differential pressure circuit 12.
has been entered.

From the differential pressure circuit 12 are a pressure sensor 10 and a pressure sensor 1.
A differential pressure signal corresponding to the differential pressure of 1 is output.

That is, pressure sensors 10, 11 and differential pressure circuit 12
is configured as differential pressure detecting means for detecting a cylinder differential pressure proportional to the boom moment out of the driving pressure of the outrigger 24.

The comparator 13 compares the output signal of the differential pressure circuit 12 with the set voltage VR, and when the output signal of the differential pressure circuit 12 exceeds the set voltage, generates a pulse signal with a pulse width corresponding to the cylinder differential pressure. It is configured as a pulse generating means.

The output of the comparator 13 is input to one input terminal of the AND gate 15, and the output of the pulse generator 1
4 is entered.

When a pulse signal is generated from the comparator 13, the pulse generator 14 generates a constant negative pulse T+ in synchronization with the rising edge of the pulse signal.

The output signal of the AND gate 15 is input to the comparison circuit 16 together with the output signals of the tension sensor 19, angle sensor 20, and position sensor 21, and the output signal of the AND gate 15 and the output signal of each sensor are inputted to the set value. When the threshold is exceeded, the transistor 17 is turned on and the alarm generator 1B issues an alarm.

In the above configuration, when an object is being lifted by the boom 23 of the crane 22, the pressure sensor 10.1
1, the cylinder differential pressure as shown in FIG. 3(A) is detected, and when this cylinder differential pressure exceeds the set value VR, the comparator 1 is detected as shown in FIG. 3(B).
A pulse signal is generated from 3.

Then, a negative pulse T1 is generated from the pulse generator 14 in synchronization with this pulse signal.

At this time, the pulse width T1 of the pulse signal is
If the pulse width T0 of the 4-output pulse signal is narrower than the pulse width T0, the AND gate 15 does not perform a logical AND operation, so the AND gate 15 outputs a positive pulse signal, as shown in FIG. 3(D). It will never occur.

Next, as shown in (D), (F), and (G) of FIG. 3, the pulse width T of the output of the comparator 13 is larger than the pulse width To of the pulse signal output from the pulse generator 14. When it is wide, time 1. 1. Since the logical product of the AND gate 15 is established between them, a positive pulse signal is generated from the AND gate 15, the transistor 17 is turned on, and the alarm generator 18 issues an alarm.

That is, the pulse generator 14 and the AND gate 15 are configured as alarm signal generating means that measures the pulse width of the pulse signal output from the comparator 13 and generates an alarm signal only when the measured value exceeds a set value. There is.

In this way, according to this embodiment, an alarm signal is not generated when the boom moment instantaneously exceeds the set value, and an alarm signal is generated only when the boom moment value exceeds the set value for a certain period of time. Therefore, it is possible to accurately warn of abnormalities in the boom moment.

Next, as shown in FIG. 4, a comparator 13 is inserted between the differential pressure circuit 12 and the AND gate 15, and a differentiating circuit 25, a hold circuit 26, and a comparator 27 are also inserted, and the output signal of the differential pressure circuit 12 is is output to the AND gate 15 via the comparator 13 and the differentiator 2
5. If the output signal is outputted to the AND gate 15 via the hold circuit 26 and the comparator 27, the output signal of the differential pressure circuit 12 is differentiated by the differentiating circuit 25, then held by the hold circuit 26, and the hold value is When the set value is exceeded, a signal is output from the comparator 27.

Therefore, when lifting an object with the boom 23, even if the boom moment instantaneously shows an abnormal value, it is possible to prevent an abnormal signal from being generated.

〔Effect of the invention〕

As explained above, according to the present invention, an alarm is generated only when the operating pressure of the boom is an abnormal value for a certain period of time or more, so it is possible to accurately warn of an abnormality in the boom moment, and to ensure safety. It can contribute to improving sexual performance.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, Fig. 2 is a configuration diagram of a crane, Fig. 3 is a waveform diagram of the circuit shown in Fig. 1, and Fig. 4 is a circuit diagram showing another embodiment of the present invention. Figure 5 is the configuration diagram of the conventional example, Figure 6 is the crane configuration diagram, Figure 7 is the boom operating pressure characteristic diagram during normal operation, and Figure 8 is the boom operation specification during abnormal conditions. It is a diagram. 0.11...Pressure sensor 2...Differential pressure circuit 3.27...Comparator 4...Pulse generator 5...AND gate 6... Comparison circuit 7... Transistor 8... Alarm generator 9... Tension sensor 0... Angle sensor... Position sensor 2... Crane 3... Boom 4... Outrigger 2 5... Differential circuit 6... Hold circuit Fig. 5 Fig. 6 Figure 7

Claims (1)

[Claims] (1) Differential pressure detection means for detecting the cylinder differential pressure proportional to the boom moment out of the driving pressure of the boom driving cylinder, and the cylinder difference when the cylinder differential pressure output from the differential pressure detection means exceeds a set value. It has a pulse generating means that generates a pulse signal with a pulse width corresponding to the pressure, and an alarm signal generating means that measures the pulse width of the pulse signal and generates an alarm signal when the measured value exceeds a set value. A crane safety warning system characterized by: