JP2000289986A - Safety device for crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically stop the operation of a crane before a hook hits a tip part of a boom when an automatic stop function of an excessive winding prevention means is released in an excessive winding condition and the hook is wound up. SOLUTION: In a crane provided with an excessive winding prevention switch 54 detecting an excessive winding condition during the operation to a hook rise side to stop the operation of the crane automatically and an automatic stop release switch 61 releasing its automatic stop function, a hit prevention switch 62 stopping the operation of the crane automatically before a hook hits a tip part of a boom when the automatic stop function is released and the operation to the hook rise side is done.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crane safety device for preventing a hook from hitting the end of a boom and causing damage to the hook, boom, wire rope, and the like.

[0002]

2. Description of the Related Art As shown in FIG. 7, a crane suspends a hook 53 from a distal end portion 51 of a boom 50 with a wire rope 52, and hoists and lowers a loaded hook 53 to perform a cargo handling operation. The hook 53 collides with the tip end 51 of the boom 50 when it is wound up, and the hook 53 and the boom 5
In order to prevent damage to the wire rope 52, the hook 53 and the boom 5
There is provided a winding prevention means for detecting a so-called winding state in which the distance between the zero and the leading end 51 is equal to or less than a predetermined distance and automatically stopping the operation of the crane.

In the conventional winding prevention means, a winding detection switch 54 is provided at the tip end portion 51 of the boom 50, and a winding weight 57 is suspended from a switch lever 55 via a winding wire rope 56. In the normal state, the switch lever 55 is pulled down by the winding weight 57 and the winding detection switch 54 is turned off. When the hook 53 rises and comes into contact with the winding weight 57 and the winding weight 57 is lifted, the switch lever 55 moves upward (clockwise in the figure).
Then, the winding detection switch 54 is turned on, and the winding state is detected.

[0004] Usually, a crane includes, as hydraulic actuators, a boom raising / lowering cylinder 1, a winch motor 2, a boom extension / retraction cylinder 3, a swing motor 4, and left and right vertical outrigger cylinders 5L and 5R as hydraulic actuators as shown in FIG. Have. In these hydraulic actuators, a boom hoisting cylinder 1 includes an hoisting hydraulic switching valve 11, a winch motor 2
Are hydraulic changeover valve 12 for winch, cylinder 3 for boom extension
The hydraulic pressure switching valve 13 for expansion and contraction, the hydraulic motor switching hydraulic valve 14 for the turning motor 4, and the hydraulic pressure switching hydraulic valves 15 L and 15 R for the vertical outrigger cylinders 5 </ b> L and 15 </ b> R cause hydraulic pressure to be supplied from the hydraulic pump 6 serving as a hydraulic source. It is connected to a working oil passage 7 of a crane to be supplied and a return oil passage 9 to a tank 8. The hydraulic pump 6 is driven by operating a PTO (not shown) and sends pressure oil to the working oil passage 7 side of the crane.

[0005] These hydraulic switching valves 11, 12, 13, 1
Reference numerals 4, 15L, and 15R denote three-position manual operation switching valves, which are manually operated by an operator to cause a boom raising / lowering cylinder 1, a winch motor 2, a boom extending / retracting cylinder 3, a swing motor 4, a right / left Of the vertical outrigger cylinders 5L, 5R can be operated. In the neutral position, the working oil passage 7 is communicated with the return oil passage 9.

The lifting hydraulic switching valve 11 is provided with a boom raising switch 58 which is turned on when the boom is raised. The hydraulic switching valve 12 for winch is turned on when the winch is wound upward. Winch hoisting switch 59
And a boom extension switch 60 that is turned on when operated to the boom extension side.

[0007] A main relief valve 10 and an unload valve 20 are provided in parallel between the working oil passage 7 and the return oil passage 9. An electromagnetic valve 21 for the unload valve is provided between the vent of the unload valve 20 and the return oil passage 9.
Is provided. This unload valve solenoid valve 21
Operates, the unload valve 20 operates to unload the pressure oil from the pump 6.

The winch motor 2 includes a low pressure hoisting switching valve 1
The winch 2 can be wound in the low pressure state set by the low pressure relief valve 17 by switching the low pressure hoisting switching valve 16. When the hook 53 is stored, the hook 53 is wound up in a low pressure state.
3 is brought into contact with a hook guide member 63 provided at the distal end portion 51 of the boom 50.
Are stored laterally while being guided by the hook guide member 63.

The swing motor 4 has a swing motor lock cylinder 18. The swing motor lock cylinder 18 is connected to a back pressure valve 19 provided in the working oil passage 7. When the pressure oil is supplied to the passage 7, the lock of the swing motor 4 is released by the back pressure generated by the back pressure valve 19. In this crane, the electric circuit which operates by detecting the winding state of the winding detection switch 54 is as shown in FIG.

That is, an automatic stop circuit 23 and an alarm circuit 24 are connected in parallel between the power supply 22 and the winding detection switch 54. The automatic stop circuit 23 is connected in series with a winch hoist switch 59, a solenoid 21S of the unload valve solenoid valve 21, and an automatic stop release switch 61 serving as automatic stop release means. A boom starting switch 58 and a boom extending switch 60 are connected in parallel with the switch 59. The alarm circuit 24 is provided with an alarm buzzer 25.

In the crane operation, the hook 53 is lifted and the distance between the tip end portion 51 of the boom 50 and the hook 53 is reduced when the winch is wound up, the boom is erected, and the boom is extended. When the operation for raising the hook is performed, one of the winch hoisting switch 59, the boom starting switch 58, and the boom extending switch 60 is turned on.

During the operation of raising the hook, the hook 53
Rises to a winding state, the winding detection switch 54 is
The alarm is turned on and the alarm buzzer 25 is sounded to inform the operator that the winding is over. The automatic stop release switch 61
Is always on in normal crane work,
The solenoid 21S of the unload valve solenoid valve 21 is excited to operate the unload valve solenoid valve 21. Accordingly, the unload valve 20 is activated, the hydraulic oil passage 7 is returned to the return oil passage 9, and the crane automatically stops.

In the winding state, when performing a special work that requires the hook 53 to be further wound, the automatic stop is released by turning off the automatic stop release switch 61, and the winch is wound up and the boom is lifted. Standing and boom extension can be operated.

[0014]

In the winding state, the automatic stop release switch 61 is turned off, and the hook 5 is turned off.
In order to prevent the hook 53 from colliding with the tip end 51 of the boom 50 when performing an operation of winding the crane 3, the operation of the crane must be manually stopped before the collision at the discretion of the operator. Did not.

However, it is difficult to perform a manual stop operation properly. If the operator makes a mistake and delays the stop operation, the hook 53 collides with the distal end portion 51 of the boom 50 and the hook 53 or the distal end of the boom 50 ends. There is a possibility that an accident such as damage to the portion 51 or damage or cutting of the wire rope 52 may be caused. The present invention solves such a problem in a crane, and in a case where a special operation such as releasing the automatic stop function of the winding prevention means in a winding state and further winding the hook is performed. Another object of the present invention is to provide a crane safety device capable of automatically stopping the operation of the crane immediately before the hook collides with the boom tip and preventing the hook, the boom tip or the wire rope from being damaged. And

[0016]

SUMMARY OF THE INVENTION A safety device for a crane according to the present invention comprises a hook guide member pivotally supported at the tip of a boom so as to be vertically rotatable, and a hook guide member when the hook pushes up the hook guide member. The above problem is solved by providing a collision prevention switch for detecting the upward rotation of the crane and stopping the operation of the crane.

In the safety device for a crane according to the present invention, since the hook pushes up the hook guide member before the hook collides with the end of the boom, the operation of the crane is automatically stopped by the collision prevention switch. Therefore, damage to the hook, the end of the boom, or the wire rope is prevented. As a crane safety device of the present invention, a winding-over prevention means for detecting a winding state during operation on the hook raising side and automatically stopping operation of the crane, and an automatic stop for releasing an automatic stop function of the winding-over prevention means In a crane equipped with a release means, when the automatic stop function of the overwinding prevention means is released and the hook is raised, the crane operation is automatically stopped before the hook collides with the boom tip. Collision preventing means can be provided.

In this case, if a winding state occurs during the operation of raising the hook, the operation of the crane is automatically stopped by the winding prevention means. Also, when releasing the automatic stop function of the winding prevention means and performing an operation on the hook rising side,
Before the hook collides with the tip of the boom, the operation of the crane is automatically stopped by the collision prevention means. Therefore, damage to the hook, the end of the boom, or the wire rope is prevented.

As a collision preventing means, a hook guide member pivotally supported by the tip of the boom so as to be vertically rotatable, and when the hook pushes up the hook guide member, the upward rotation of the hook guide member is detected. By providing a collision prevention switch that stops the operation of the crane, it is not necessary to change the shape of the boom tip, and simply attach the collision prevention switch to the boom tip. Will be able to

At the time of stop, the hook has reached a position where it can not be wound any more, so that the work which must be performed until the automatic stop is released is not hindered.

[0021]

FIG. 1 is a front view of a tip of a boom of a crane provided with a safety device according to an embodiment of the present invention. FIG. 2 is a sectional view taken along line AA of FIG. Is B- in FIG.
FIG. 4 is a sectional view taken along the line B, FIG. 4 is a rear view of the tip of the boom, FIG. 5 is an explanatory view of the operation of the collision prevention switch, and FIG. 6 is an electric circuit diagram of the safety device of the crane.

The crane has a tip 51 of a boom 50.
The hook 53 is hung by a wire rope 52 from above. 7, a winding detection switch 54 is provided at the tip end 51 of the boom 50 as a winding prevention means, and a winding weight 57 is suspended from a switch lever 55 via a winding wire rope 56. are doing. Winding detection switch 54
In the normal state, the switch lever 55 is
It was pulled down at 7 and turned off. Hook 53
Rises and contacts the winding weight 57, and the winding weight 5
When the lifting lever 7 is lifted, the switch lever 55 is rotated upward, the winding detection switch 54 is turned on, and the winding state is detected.

This crane is similar to the crane shown in FIG.
, Winch motor 2, boom extension / retraction cylinder 3, swing motor 4, left and right vertical outrigger cylinders 5 </ b> L, 5 </ b> R
And These hydraulic actuators include a hydraulic switching valve 11 for raising and lowering a boom, a hydraulic switching valve 12 for a winch, a winch motor 2, a hydraulic switching valve 13 for extending and retracting a boom, and a turning motor 4 for turning hydraulic pressure. The switching valve 14 and the vertical outrigger cylinders 5L and 5R are connected to the working oil passage 7 of the crane to which the working pressure oil is supplied from the hydraulic pump 6 serving as a hydraulic source via the outrigger hydraulic switching valves 15L and 15R, and to the tank 8. It is connected to the return oil passage 9. The hydraulic pump 6 is driven by operating a PTO (not shown) and sends pressure oil to the working oil passage 7 side of the crane.

These hydraulic switching valves 11, 12, 13, 1
Reference numerals 4, 15L, and 15R denote three-position manual operation switching valves, which are manually operated by an operator to cause a boom raising / lowering cylinder 1, a winch motor 2, a boom extending / retracting cylinder 3, a swing motor 4, a right / left Of the vertical outrigger cylinders 5L, 5R can be operated. In the neutral position, the working oil passage 7 is communicated with the return oil passage 9.

The hydraulic switching valve 11 for raising and lowering is provided with a boom starting switch 58 which is turned on when operated toward the boom standing side, and the hydraulic switching valve for winch 12 is turned on when operated toward the upper side of the winch. Winch hoisting switch 59
And a boom extension switch 60 that is turned on when operated to the boom extension side.

A main relief valve 10 and an unload valve 20 are provided in parallel between the working oil passage 7 and the return oil passage 9. An electromagnetic valve 21 for the unload valve is provided between the vent of the unload valve 20 and the return oil passage 9.
Is provided. This unload valve solenoid valve 21
Operates, the unload valve 20 operates to unload the pressure oil from the pump 6.

The winch motor 2 includes a low-pressure hoisting switching valve 1
The winch 2 can be wound in the low pressure state set by the low pressure relief valve 17 by switching the low pressure hoisting switching valve 16. When the hook 53 is stored, the hook 53 is wound up in a low pressure state.
3 is brought into contact with a hook guide member 63 provided at the distal end portion 51 of the boom 50.
Are stored laterally while being guided by the hook guide member 63.

The turning motor 4 is provided with a turning motor lock cylinder 18, which is connected to a back pressure valve 19 provided in the working oil passage 7, and When the pressure oil is supplied to the passage 7, the lock of the swing motor 4 is released by the back pressure generated by the back pressure valve 19. In this crane, the hook guide member 6 constituting the collision prevention means is provided.
3 is a support pin 65 fixedly connected to the base end side of a bracket 64 whose base end upper part is provided in the middle of the end part 51 of the boom 50.
Is mounted so as to be rotatable with respect to. A detection pin 66 is fixed to the upper end of the hook guide member 63.

At the tip end of the bracket 64, a detection pin 6
A concave portion 64A for receiving the detection pin 6 is formed.
The movement range of 6 is restricted by the recess 64A. A spring 6 is provided between the bracket 64 and the hook guide member.
The detection pin 66 is constantly urged by the spring 67 so as to contact the lower edge of the recess 64A.

Also, a recess 64 on the tip side of the bracket 64
Above A, a collision prevention switch 62 is provided. The collision prevention switch 62 is always a limit switch
The hook 53 is wound up as shown in FIG.
3 is pushed up and the detection pin 66 moves upward,
It is configured to be on.

The electric circuit of the safety device for the crane is as shown in FIG. That is, the automatic stop circuit 23 and the alarm circuit 2 are provided between the power supply 22 and the winding detection switch 54.
4 are connected in parallel. In the automatic stop circuit 23,
The winch hoist switch 59, the solenoid 21S of the unload valve solenoid valve 21, and the automatic stop release switch 61 serving as automatic stop release means are connected in series. The switch 58 and the boom extension switch 60 are connected.

The automatic stop circuit 23 has a collision prevention switch 62 connected in parallel with the automatic stop release switch 61. Even when the automatic stop release switch 61 is off, the collision prevention switch 62 is turned on. If possible, the solenoid 21S can be excited. The alarm circuit 24 is provided with an alarm buzzer 25.

In the crane operation, the hook 53 is raised and the distance between the tip end portion 51 of the boom 50 and the hook 53 is reduced when the winch is wound up, the boom is erected, and the boom is extended. When the operation for raising the hook is performed, one of the winch hoisting switch 59, the boom starting switch 58, and the boom extending switch 60 is turned on.

During the operation for raising the hook, the hook 53
Rises to a winding state, the winding detection switch 54 is
The alarm is turned on and the alarm buzzer 25 is sounded to inform the operator that the winding is over. The automatic stop release switch 61
Is always on in normal crane work,
The solenoid 21S of the unload valve solenoid valve 21 is excited to operate the unload valve solenoid valve 21. Accordingly, the unload valve 20 is activated, the hydraulic oil passage 7 is returned to the return oil passage 9, and the crane automatically stops.

In the winding state, when performing a special operation in which it is necessary to further wind the hook 53, the automatic stop is released by turning off the automatic stop release switch 61. Standing and boom extension can be operated. When the operation for raising the hook is performed with the automatic stop release switch 61 turned off, the hook 53 comes into contact with the hook guide member 63 before the hook 53 collides with the tip end portion 51 of the boom 50, and the hook guide member 63 Is pushed up, the detection pin 66 moves upward, and the collision prevention switch 62 is turned on, so that the solenoid 21S of the unload valve solenoid valve 21 is excited to operate the unload valve solenoid valve 21. Accordingly, the unload valve 20 is activated, the hydraulic oil passage 7 is returned to the return oil passage 9, and the crane automatically stops.

Table 1 shows the state of each switch 54, 61, 62 and the working mode of the crane in the crane safety device.
Shown in

[0037]

[Table 1] As shown in Table 1, in the crane safety device, when a winding state occurs during the operation to the hook rising side, the operation of the crane is automatically stopped by the winding detection switch 54. Also,
When the automatic stop release switch 61 is turned off and the hook is raised, the hook 53 is moved to the boom 50 position.
The operation of the crane is automatically stopped by the collision prevention switch 62 before colliding with the tip 51 of the crane. Therefore, damage to the hook 53, the tip 51 of the boom 50, or the wire rope 52 is prevented.

At the time of stopping by the collision prevention switch 62,
Since the hook 53 has reached a position where it cannot be wound any more, it does not hinder the work that must be performed until the automatic stop is released. Further, even if the winding detection switch 54 fails and does not operate due to a failure, and the automatic stop cannot be performed even in the winding state, the hook 53 is moved by the collision prevention switch 62 to the leading end 5 of the boom 50.
The operation of the crane can be automatically stopped before colliding with 1.

In normal crane work, the automatic stop release switch 61 is supposed to be turned on. However, there are cases where the crane operation is performed by mistake while the automatic stop release switch 61 is kept off. In this case, even if the winding detection switch 54 is turned on, the crane does not automatically stop. However, since the operation of the crane is automatically stopped in the end, the collision between the hook 53 and the tip 51 of the boom 50 may be prevented. Can be prevented.

[0040]

As described above, according to the safety device for a crane of the present invention, when the crane is in a winding state during the operation of raising the hook, the operation of the crane is automatically stopped by the winding prevention means, and When the automatic stop function of the prevention means is released and the operation on the hook rising side is performed, the operation of the crane is automatically stopped by the collision prevention means before the hook collides with the tip of the boom. Therefore, damage to the hook, the end of the boom, or the wire rope is prevented.

As a collision preventing means, a hook guide member pivotally supported by the tip of the boom so as to be vertically rotatable, and detecting upward rotation of the hook guide member when the hook pushes up the hook guide member. By providing a collision prevention switch that stops the operation of the crane, it is not necessary to change the shape of the boom tip, and simply attach the collision prevention switch to the boom tip. Will be able to

[Brief description of the drawings]

FIG. 1 is a front view of a tip of a boom of a crane provided with a safety device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 2;

FIG. 4 is a rear view of the tip of the boom.

FIG. 5 is a diagram illustrating the operation of a collision prevention switch.

FIG. 6 is an electrical circuit diagram of a crane safety device.

FIG. 7 is a side view of a tip portion of a conventional crane boom.

FIG. 8 is a hydraulic circuit diagram of a conventional crane.

FIG. 9 is an electric circuit diagram of a conventional crane safety device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boom raising / lowering cylinder 2 Winch motor 3 Boom expansion / contraction cylinder 4 Swing motor 6 Hydraulic pump 7 Working oil passage 8 Tank 9 Return oil passage 10 Main relief valve 11 Undulation hydraulic switching valve 12 Winch hydraulic switching valve 13 Extension hydraulic switching Valve 14 Hydraulic switching valve for turning 20 Unload valve 21 Solenoid valve for unload valve 21S solenoid 22 Power supply 23 Automatic stop circuit 24 Alarm circuit 50 Boom 51 Tip 52 Wire rope 53 Hook 54 Overwind detection switch 58 Boom start switch 59 winch Hoisting switch 60 Boom extension switch 61 Automatic stop release switch 62 Collision prevention switch 63 Hook guide member 64 Bracket 64A Recess 65 Support pin 66 Detection pin 67 Spring

Claims (3)

[Claims] 1. A hook guide member pivotally supported by a tip end of a boom so as to be vertically rotatable, and when the hook pushes up the hook guide member, an upward rotation of the hook guide member is detected to operate the crane. A safety device for a crane, comprising: a collision prevention switch for stopping the vehicle. 2. A winding-over prevention means for detecting a winding-up state during an operation to raise the hook and automatically stopping the operation of the crane;
In a crane provided with automatic stop release means for releasing the automatic stop function of the winding prevention means, when the automatic stop function of the winding prevention means is released and the operation to the hook raising side is performed, the hook is moved from the boom. A safety device for a crane, comprising collision prevention means for automatically stopping the operation of the crane before colliding with the tip. 3. A hook guide member pivotally supported by a tip end of a boom so as to be vertically rotatable, and detecting an upward rotation of the hook guide member when the hook pushes up the hook guide member. The safety device for a crane according to claim 2, further comprising a collision prevention switch for stopping operation of the crane.