JPH0820493A - Safety device for construction machine - Google Patents

Abstract

PURPOSE:To prevent danger preliminarily by informing workers of a load situation of a suspended load by connecting electric signals of an overload preventing device through a relay to three-color lamps of blue, yellow, and red. CONSTITUTION:As switches 11, 12 are put on, a blue lamp of three-color lamps 10 installed on a front surface of a crane main body is lighted, and it is lighted as far as a suspended load is less than 90% the rated load. When the real suspended load reaches 90% the rated load, an electric signal from a load cell is sent through a relay switch R2 to a converter 15, a relay R1 is actuated to put off the relay switch R1 having a contact B to light off the blue lamp. and the relay switch R1 having a contact A is put on, so a yellow lamp is lighted. In the case where the suspended load reaches 100% the rated load, the relay R2 is actuated, the relay switch R2 having the contact A is put off, and the relay R2 having the contact B is put on, so a red lamp is lighted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a construction machine, and more particularly to a safety device for informing a worker around a construction machine of a load condition of a hoisting load.

[0002]

2. Description of the Related Art Conventionally, a safety device of this type guides an electric signal from a detection device such as a load cell to a control unit of a CPU (central processing unit), compares it with a rated load signal stored in advance, and compares the load signal with that load signal. The rate was displayed on the display device provided in the driver's cab, and it was installed to inform only the driver of the load status of the lifting load. However, the rated load or the total rated load (weight including the lifting device) is determined by the strength of the boom and the stability of the machine against falling, but in actual work, the load may exceed the rated load. For example, when the lifting performance is different between the front and the side of the construction machine, the advantageous side hangs up to the rated load to make a full turn, or the boom is lowered while the load is suspended. May exceed the rated load.
In such a case, the operator can know the load condition by the load factor display device provided in the operator's cab, but the worker around the construction machine cannot. Therefore, even if the machine is on the verge of falling, a worker may enter the turning radius of the machine, which is very dangerous.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and its purpose is to inform the workers around the construction machine of the load condition of the hoisting load and prevent the danger from occurring. In point.

[0004]

In order to achieve the above object, in the present invention, an electric signal of an overload prevention device is connected to three color lights of blue, yellow and red through a relay, and the three signals are connected depending on load conditions. The configuration is such that color lights can be switched.

[0005]

According to the safety device of the present invention, the electric signal from the detector of the overload prevention device can be led to the three color lights of blue, yellow and red through the relay, so that it is located around the construction machine. The worker can know the load status of the lifting load from the color of the lit lamp, and can work safely.

[0006]

Embodiments of the present invention will be described below with reference to FIGS. Reference numeral 1 denotes a crane main body, and a substantially angled base frame 2 is fixed to the front portion of the crane main body 1, and a winch drum 3 having a built-in hydraulic motor is arranged at the upper end of the base frame 2, and the winch is provided. One end of a telescopic boom 4 is pivotally mounted near the drum 3. Further, one end of a depression / elevation cylinder 5 for raising and lowering the telescopic boom 4 is pivotally attached to the lower portion of the base frame 2, and the other end of the depression / elevation cylinder 5 is pivotally attached to the lower surface of the telescopic boom 4. The other end of the hoisting rope 6 whose one end is wound around the winch drum 3 is hung between the head sheave 8 and the hook sheave 9 via the top sheave 7, and then passed through the top sheave 7 again to the base frame 2 to the extendable frame. 4 is connected to a load cell (not shown) of an overload prevention device attached to
A three-color lamp 10 is mounted on the front surface of the front of the crane body 1 at a position where it can be easily seen. Switches 11 and 12 are provided on the 90% signal line 13 (hereinafter referred to as 90% line) of the load cell and the fuse line 14, respectively. The switches 11 and 12 are interlocked with each other, and in the operation of operating the overload prevention device, the switch is always on (ON), and as long as the actual lifting load is less than 90% of the rated load, a three-color blue lamp. Lights up.

One terminal of the blue lamp of the three-color lamp 10 is connected to the converter 15 via a relay switch R1 having a B contact and a relay switch R2 having an A contact, and the other terminal of the blue lamp is connected to the relay R1. It is connected in parallel to the relay R2 of the converter 15 and the 100% signal line 16 (hereinafter referred to as 100% line) of the load cell. Further, one terminal of the yellow lamp of the three-color lamp is connected to the converter 15 via the relay switch R1 having the A contact and the relay switch R2 having the A contact, and the other terminal of the yellow lamp is connected to the relay R1. It is connected in parallel to the converter 15 and the relay R2 of the 100% line. Further, one terminal of the red lamp of the three-color lamp is connected to the converter 15 via the relay switch R2 having a B contact, and the other terminal of the red lamp is connected to the converter 15 and the relay R of the 100% line 16.
2 is connected in parallel. On the other hand, the converter 15 has 9
Relay R with 0% line having switch 11 and A contact
It is connected via 2. Here, the relay R1 is always OFF, and is switched ON when the actual lifting load reaches 90% of the rated load. Also, relay R2 is always O
With N, it switches to OFF when the actual lifting load reaches 100% of the rated load.

Next, the operation of the present invention will be described. First, when trying to operate the overload prevention device, the switches 11 and 12 are turned on (ON). In this state, the blue lamp of the three-color lamp 10 lights up. The blue lamp is lit as long as the actual lifting load is less than 90% of the rated load. Actual lifting load is 9 of rated load
When it reaches 0%, the electric signal from the load cell is led to the converter 15 via the switch 11 and the relay switch R2, the intermittent signal is converted into a continuous signal by the converter 15, and the relay R1 is operated to have the B contact. The relay switch R1 is turned off, the blue lamp circuit of the three-color light is cut off, the blue lamp is turned off, the relay switch R1 having the A contact is turned on, and the yellow lamp circuit of the three-color light is turned on. , The yellow lamp lights up. Also, when the actual hoisting load reaches 100% of the rated load, the relay R2 is activated, and the relay switch R2 having the 90% line and the A contact of the blue / yellow lamp circuit of the three-color lamp is turned off and the circuit is turned off. At the same time as being cut off, the relay switch R2 having the B contact of the red lamp circuit of the three-color lamp is turned on and the red lamp is turned on.

[0009]

According to the present invention, with the configuration described in detail in the above-mentioned one embodiment, the operator around the construction machine can know the load condition of the actual lifting load with respect to the rated load by the three-color light. Therefore, the work can be performed safely, which is extremely effective.

[Brief description of drawings]

1 is a side view of the entire crane employing the present invention.

FIG. 2 is an electric circuit diagram according to the present invention.

[Explanation of symbols]

 3 winch drum 4 boom 6 hoisting rope 10 3 color light 15 converter

Claims (2)

[Claims] 1. An overload prevention device for a construction machine, which detects a lifting load of a crane or the like, and stops the operation when the lifting load reaches a rated load, wherein the detected signal is transmitted through a relay in blue, yellow and Lead to a red three-color light,
A safety device for a construction machine, which is capable of switching the above three color lights depending on a load ratio of an actual hoisting load with respect to a rated load. 2. A three-color blue lamp lights when the load ratio of the actual hoisting load with respect to the rated load is low, a yellow lamp lights when the load ratio reaches 90%, and the load ratio is 100. The safety device for a construction machine according to claim 1, wherein the red lamp is configured to be turned on when the percentage reaches%.