JP2000063080A - Hook housing device for mobile crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safer hook housing device for a mobile crane by preventing an accidental drop against an intention of an operator even when the operator carelessly selects a hook housing mode. SOLUTION: A hook housing device is provided with a hoisting load detecting means 22 detecting a hoisting load hoisted by a hook and a controlling means C lowering hoisting side oil pressure in a hydraulic motor 17 when a hoisting load detected by means of the hoisting load detecting means 22 is the predetermined value or less in a hook housing mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hook storage device for a mobile crane, and more particularly, even if the hook storage mode is set when the suspension load exceeds a predetermined value, the suspension load does not drop and the hook is overloaded. The present invention relates to a hook storage device for a mobile crane that stops at a winding position.

[0002]

2. Description of the Related Art For example, Japanese Utility Model Laid-Open No. 4-51493.
"If you select the hook storage mode in which the hook that can be lifted from the tip of the boom is hoisted to the storage position via the wire wound around the winch driven by the hydraulic motor, "Control means for lowering the upper hydraulic pressure".

[0003]

However, in the above-mentioned prior art, when the operator carelessly selects the hook storage mode while hoisting a suspended load, the hoisting oil pressure of the hydraulic motor decreases, and hoisting at this time occurs. If the force is smaller than the hanging load, there is a risk that the hanging load will drop against the operator's will.

The present invention has been made in view of the above problems, and prevents the suspended load W from dropping against the intention of the operator even if the operator carelessly selects the hook storage mode. It is an object of the present invention to provide a hook storage device for a mobile crane, which has improved safety by means of the above.

[0005]

In order to achieve the above object, the hook retractor for a mobile crane according to the first aspect of the present invention is wound around a winch driven by a hydraulic motor. Select the hook storage mode when hoisting a hook that can be lifted and lowered from the boom tip via a wire to the retracted position beyond the overwinding position. A suspending load detecting means for detecting a suspending load and a controlling means for lowering the hoisting hydraulic pressure of the hydraulic motor in the hook storage mode and when the suspending load detected by the suspending load detecting means is equal to or less than a predetermined value. Characterize.

According to the first invention, in the hook storing mode,
Moreover, the hoisting hydraulic pressure of the hydraulic motor decreases when the suspension load is equal to or less than a predetermined value. That is, even in the hook storing mode, the hoisting hydraulic pressure of the hydraulic motor does not decrease if the suspension load exceeds the predetermined value. Therefore, even if the operator inadvertently selects the hook storage mode while hoisting a suspended load, the hoisting hydraulic pressure of the hydraulic motor is generated according to the suspended load, and the suspended load drops against the operator's will. It is prevented and the safety is improved. Also, if the hanging load is less than or equal to a predetermined value while hoisting the hanging load in the hook storage mode,
Since the hoisting oil pressure of the hydraulic motor is reduced as usual, the force when the hook abuts on the boom tip is reduced and damage to the hook and the boom tip is prevented.

A hook retractor for a mobile crane according to a second aspect of the present invention is the hook retractor according to the first aspect, which is provided with overwinding detecting means for detecting that the hook has been wound up to an overwinding position.
The control means stops the hydraulic motor in the hook storage mode, when the suspension load detected by the suspension load detection means exceeds the predetermined value, and when the overwinding detection means detects the overwinding position of the hook. And

According to the second invention, in addition to the action and effect of the first invention, the hoisting hydraulic pressure of the hydraulic motor does not decrease when the suspension load exceeds the predetermined value even in the hook storage mode. When the hook is wound up to the overwind position, the hydraulic motor stops. Therefore, the hook is not wound up to the retracted position without lowering the hoisting hydraulic pressure of the hydraulic motor, which prevents the hook from coming into contact with the boom tip and damaging the hook and the boom tip.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. A mobile crane equipped with the hook storage device according to the present invention will be described with reference to FIG. Outriggers 2 are attached to the front, rear, left and right of the vehicle body 1 of the mobile crane. A cab 3 is mounted on the vehicle body 1,
A base end boom 4 for accommodating a telescopic boom is mounted beside the cab 3 so as to be rotatable around a foot pin P. A hoisting cylinder 5 is attached between the vehicle body 1 and the base end boom 4. A main winch 6 and an auxiliary winch 7 are attached to the base of the base end boom 4, and a main wire 8 wound around the main winch 6 is attached.
Hangs the main hook 9 so as to be able to move up and down via the tip of the base boom 4. The auxiliary wire 10 wound around the auxiliary winch 7 suspends the auxiliary hook 12 from the tip portion 11a of the tip boom 11 of the telescopic boom. The main hook 9 is attached to the tip portion 11 a of the tip boom 11, and the main hook 9 is attached to the tip portion 11 a.
An overwinding detection switch 14 for detecting that the hook has been overwound by approaching a predetermined amount to a is installed. As for the auxiliary hook 12, the overwinding detection switch 1 of the main hook 9 is also used.
An overwinding detection switch similar to that of No. 4 is installed. The operation of the main hook 9 will be described below, but the description of the auxiliary hook 12 will be omitted because it is the same.

As shown in FIG. 1, the outrigger 2 is extended to raise the vehicle body 1 from the ground GL by a predetermined amount, and the hoisting cylinder 5 is contracted to cause the base boom 4 to hoist over the vehicle body 1 from the running state. When the cylinder 5 is extended and the base end boom 4 is erected around the foot pin P, the mobile crane lifts the load W.
Ready to work. In this state, the tip portion 11 of the tip boom 11 is inserted through the main wire 8 wound around the main winch 6.
By the main hook 9 suspended from a, the suspended load W suspended via the suspension wire 13 is moved up and down. When the main hook 9 approaches the tip portion 11a of the tip boom 11 by a predetermined amount and reaches the overwinding position, the main hook 9 contacts the overwinding detection switch 14 and the overwinding state of the main hook 9 is detected.

Next, a first embodiment of the hook storing device will be described with reference to FIG. FIG. 2 is an example of a hydraulic circuit representing the first embodiment. The hydraulic pump 15 is connected to the hydraulic motor 17 for driving the main winch 6 shown in FIG. 1 via the operation valve 16, the winding side pipe line 18a and the winding side pipe line 18b. The low-pressure relief valve 1 is installed in the winding-up line 18a of the hydraulic motor 17.
9 is connected to the pressure setting spring 20 of the low pressure relief valve 19.
The set pressure of is set variably by the solenoid 21. The pressure switch 22 is connected to the hook winding upper pipe line 18a and detects whether the suspension load is equal to or less than a predetermined value by the hydraulic pressure of the hook winding upper pipe line 18a. The hook storage mode selection switch 23 is installed in the cab 3 of the vehicle body 1 shown in FIG. 1, and selects the hook storage mode when the main hook 9 is stored. The controller 25 outputs a demagnetization signal to the solenoid 21 when the hook storage mode signal is input from the hook storage mode selection switch 23 and the detection signal indicating that the suspension load is equal to or less than a predetermined value is input from the pressure switch 22. In addition, the controller 25
Even if a hook storage mode signal is input from the hook storage mode selection switch 23, the solenoid 2 is activated when a detection signal indicating that the suspension load exceeds a predetermined value is input from the pressure switch 22.
The excitation signal is output to 1. As described above, the control device C according to the present embodiment includes the low pressure relief valve 19, the pressure setting spring 20, the pressure setting solenoid 21, and the controller 2.
5 is provided.

According to the configuration of the first embodiment, the operation valve 16
Is operated to the position a, the oil discharged from the hydraulic pump 15 drives the hydraulic motor 17 to the hoisting side via the hoisting line 18a. Similarly, when the operation valve 16 is operated to the b position, the oil discharged from the hydraulic pump 15 is transferred to the hydraulic motor 1 via the lower side conduit 18b.
7 is driven to the lowering side. Further, when the operation valve 16 is operated to the c position, the oil discharged from the hydraulic pump 15 is discharged to the winding side conduit 18a.
Also, the hydraulic motor 17 is stopped because it is cut off from both the winding side conduit 18b. Hook storage mode is selected,
If the suspension load is below a predetermined value, the controller 25
The solenoid 21 is demagnetized in response to the command from, and the set pressure of the pressure setting spring 20 of the relief valve 19 decreases. For this reason, the oil pressure in the hoisting line 18a of the hydraulic motor 17 decreases, and the winch rotation torque during hoisting decreases. Therefore, the force when the main hook 9 is wound up to the hook storage position and abuts on the boom tip 11a is reduced, and damage to the main hook 9 and the boom tip 11a can be prevented. Even if the hook storage mode is selected, if the suspension load exceeds the predetermined value, the solenoid 21 is excited and the relief valve 19 is activated.
The setting pressure of the pressure setting spring 20 does not decrease. Therefore, even when the operator may carelessly touch the hook storage mode selection switch 23 to select the hook storage mode when the suspension load exceeds the predetermined value, the winding position of the hydraulic motor 17 may be increased. The hydraulic pressure never drops. Therefore, it is possible to prevent the suspended load W from being lowered against the intention of the operator, and the safety is improved.

A second embodiment of the hook storage device will be described with reference to FIG. In the second embodiment, in addition to the configuration of the first embodiment shown in FIG. 2, as shown in FIG. 1, the main hook 9 further approaches the boom tip 11a by a predetermined amount, and the main hook 9 is wound up to the overwinding position. An overwinding detection switch 14 that detects that the winding is performed is installed. And this overwinding detection switch 1
The signal No. 4 is input to the controller 25. Control pump 2
7 is connected to the pump port of the pilot pressure control valve 28, one output port of the pilot pressure control valve 28 is connected to the pilot portion 16a of the operation valve 16 via the opening / closing valve 26, and the other output port is the operation valve. It is connected to 16 pilot units 16b. Control device C in this embodiment
Is a low pressure relief valve 19, a pressure setting spring 20, a pressure setting solenoid 21 and a controller 2 of the first embodiment.
5, an on-off valve 26 and its solenoid 26a are provided.

The controller 25 inputs the hook storage mode signal from the hook storage mode selection switch 23 and the overwinding detection means 14 when the suspension load detection signal from the pressure switch 22 exceeds the predetermined value. When the overwinding detection signal is not input, the demagnetization signal is output to the solenoid 26a. In addition, the controller 25 inputs the hook storage mode signal from the hook storage mode selection switch 23, and also inputs the hook storage mode signal from the pressure switch 22 and the detection signal from the overwinding detection means 14 when the suspension load exceeds the predetermined value. When the winding detection signal is input, an excitation signal is output to the solenoid 26a. The on-off valve 26 is a solenoid 26a.
Is demagnetized, it switches to the a position and solenoid 26a
When is excited, it switches to the b position. Since other configurations are similar to those of the first embodiment, description thereof will be omitted.

According to the configuration of the second embodiment, when the hook storage mode is selected and the suspension load is equal to or less than the predetermined value, the solenoid 21 is demagnetized by a command from the controller 25 as in the first embodiment. As a result, the set pressure of the pressure setting spring 20 of the relief valve 19 decreases. Therefore, the winch rotation torque during winding is reduced. At the same time, if the main hook 9 is not wound up to the overwinding position, the solenoid 26a is demagnetized by a command from the controller 25 and the opening / closing valve 26 is set to the a position. Therefore, when the pilot pressure control valve 28 is operated to the a position, the operation valve 16 is set to the a position, and the discharge oil of the hydraulic pump 15 is supplied to the hoisting line 18a of the hydraulic motor 17 to turn the hydraulic motor 17 to the hoisting side. To drive. Further, when the pilot pressure control valve 28 is operated to the b position, the operation valve 16 becomes the b position, and the hydraulic pump 15
Of the oil is supplied to the unwinding side conduit 18b of the hydraulic motor 17 to drive the hydraulic motor 17 to the unwinding side. When the pilot pressure control valve 28 is operated to the c position, the control pressure of the control pump 27 is not supplied to the pilot portions 16a and 16b of the operation valve 16, so that the operation valve 16 is in the c position (neutral) and the hydraulic motor 17 is stopped. . In this way, the hydraulic motor 17 is freely driven according to the operation of the pilot pressure control valve 28, and even if the main hook 9 is wound up to the hook storage position, the winch rotation torque at the time of winding is small, so that the main hook is wound. The force when 9 comes into contact with the boom tip 11a is reduced, and damage to the main hook 9 and the boom tip 11a is prevented.

Next, even if the hook storing mode is selected, if the suspension load exceeds the predetermined value, the solenoid 21 is instructed by the controller 25 as in the first embodiment.
Is excited and the set pressure of the pressure setting spring 20 of the relief valve 19 does not decrease. Further, if the main hook 9 is not wound up to the overwinding position, the controller 25 does not input the overwinding detection signal from the overwinding detecting means 14, so the on-off valve 26
To position a. Therefore, similarly to the above, the hydraulic motor 17 is freely driven according to the operation of the pilot pressure control valve 28.

In this state, when the main hook 9 is wound up to the overwinding position and an overwinding detection signal is input from the overwinding detection switch 14 to the controller 25, the controller 25 outputs an excitation signal to the solenoid 26a to open the open / close valve 26. Switch to position b. Therefore, the pilot portion 16 of the operation valve 16
a is drained, and the control pressure of the control pump 27 is not supplied to the pilot portion 16a of the operation valve 16 even if the pilot pressure control valve 28 is operated to the a position. Therefore, the operation valve 16 is c
The position (neutral) is reached, and the hydraulic motor 17 stops. Thus, even if the operator carelessly selects the hook storage mode without lowering the winding-side hydraulic pressure of the hydraulic motor 17, the hydraulic motor 17 stops when the main hook 9 is wound up to the overwinding position. . Therefore, the main hook 9 is prevented from being wound up to the retracted position, and the main hook 9 and the boom tip 11a are prevented from being damaged when the main hook 9 contacts the boom tip 11a.

[Brief description of drawings]

FIG. 1 is a side view of a mobile crane equipped with a hook storage device according to the present invention.

FIG. 2 is a diagram showing an example of a control circuit according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an example of a control circuit of a second embodiment according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Car body, 2 ... Outrigger, 3 ... Operator room, 4 ... Base boom, 5 ... Elevating cylinder, 6 ... Main winch, 7 ... Auxiliary winch, 8 ... Main wire, 9 ... Main hook, 10 ... Auxiliary wire, 11 ... tip boom, 11a ... tip part, 12 ... auxiliary hook, 13 ... suspension wire, 14 ... over-winding detection switch, 1
5 ... Hydraulic pump, 16 ... Operation valve, 16a, 16b ... Pilot part, 17 ... Hydraulic motor, 18a ... Winding upper side pipe line, 1
8b ... Lowering side pipe line, 19 ... Low pressure relief valve, 20 ... Pressure setting spring, 21, 26a ... Solenoid, 22 ... Pressure switch, 23 ... Hook storage mode selection switch, 25 ...
Controller, 26 ... Open / close valve, 27 ... Control pump, 28
… Pilot pressure control valve, C… Control device, W… Suspended load W,
P ... Footpin, GL ... Ground.

Claims (2)

[Claims] 1. A hook (9) suspended up and down from a boom tip (11a) via a wire wound around a winch driven by a hydraulic motor (17) is stored beyond the overwinding position. In the hook storage device of a mobile crane that selects the hook storage mode when hoisting to the position, the suspension load detection means (22) that detects the suspension load to be suspended by the hook (9), and the suspension system in the hook storage mode. Hook storage of a mobile crane, characterized by comprising: a control means (C) for lowering the hoisting hydraulic pressure of the hydraulic motor (17) when the suspension load detected by the load detection means (22) is below a predetermined value. apparatus. 2. The hook storage device for a mobile crane according to claim 1, further comprising an overwinding detection means (14) for detecting that the hook (9) has been wound up to an overwinding position, and a control means.
(C) is in the hook storage mode and the suspension load detection means (2
Movement characterized in that the hydraulic motor (17) is stopped when the suspension load detected in 2) exceeds the specified value and the overwinding detection means (14) detects the overwinding position of the hook (9). Retractor for hook type crane.