JP2000086192A - Revoluing operation circuit of high lift work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve impact applied to an operator by forming an operation delay circuit including a throttle valve, which stops a rotating motor at the time of revolution or slows down braking operation with a negative brake. SOLUTION: In a revoluing operating circuit, the operation lever of a pilot valve 24 is returned to its original position. The differential pressure across the first throttle valve 31 first becomes large by the residual pressure of a pilot line 26, and the second throttle valve 32 is controlled so as to throttle the pilot line 26. The return oil to an oil tank 25 in the pilot line 26 is throttled by the first and second throttle valves 31, 32. By the throttling operation, the return oil has small flow rate, the pressure in the pilot line 26 decreases gradually, and control valves 15, 23 are switched gradually. Revoluing stop is conducted smoothly, therefore it is possible to prevent generation of an accident such as collision with the frame of the periphery of a bench, for which the body of an operator on the bench is swung by rapid revoluing stop.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a revolving unit installed on a running body via a revolving device, a telescopic boom is mounted on the revolving unit so as to be able to move up and down, and a work table is mounted on a tip of the telescopic boom. The present invention relates to an operation circuit for performing a swiveling operation of the revolving body on a workbench in an aerial work vehicle.

[0002]

2. Description of the Related Art In an aerial work vehicle, an operator on a work table operates an operation lever or a switch on an operation panel installed on the work table to run, turn, extend and retract a boom, and extend and retract the boom. Other operation control is performed. Such operation control is performed by operating and stopping a hydraulic cylinder or a hydraulic motor by switching a control valve. The turning device on the main body side has a negative brake, and when the turning device is started, by operating the operation lever on the worktable,
The brake control valve is switched to release the negative brake by hydraulic pressure, and at the same time, the swing motor control valve is switched to start the swing motor. When the turning is stopped, the control lever is returned to the original position, thereby switching the control valves of the negative brake and the turning motor to stop the turning operation.

[0003]

In an aerial work vehicle, a worker works on a workbench at an aerial position, and the operation at the time of turning stop suddenly depends on the manner of operating the operating lever. In some cases, the worker's body on the workbench shakes due to inertia, resulting in poor workability and causing fear to the worker.

The present invention has been made in view of the above-mentioned problems of the prior art, and provides a turning operation circuit which improves workability during turning work of a turning body of an aerial work vehicle and reduces shock applied to an operator. The purpose is to do.

[0005]

According to a first aspect of the present invention, there is provided a turning operation circuit for an aerial work vehicle, wherein a turning body is installed on a traveling body via a turning device, and a telescopic boom can be raised and lowered on the turning body. Attachment, a work platform is attached to the tip of the telescopic boom, and the work platform, the turning device, the telescopic boom equipped with a telescopic boom operating device, the turning motor of the turning device and its negative brake At least one of the operation circuits is provided with an operation delay circuit including a throttle valve that stops the turning motor when turning is stopped or slows down a brake application operation by a negative brake.

As described above, by providing the operation delay circuit, the turning is stopped slowly, the impact at the time of stopping the turning is reduced, and the workability is improved.

The turning operation circuit of the aerial work vehicle according to claim 2 is
In claim 1, each operation circuit of the swing motor of the swing device and the negative brake thereof has a control valve for controlling them, and a pilot hydraulic line connected to the control valve, and the throttle valve is: A first throttle valve provided in the pilot hydraulic line; and a second throttle valve connected in series with the first throttle valve, wherein the second throttle valve is the first throttle valve. The throttle amount is controlled on the basis of the differential pressure between before and after.

With such a configuration of the throttle valve, when the hydraulic pressure of the pilot oil is relatively high at the start of the turning stop operation, the pressure difference before and after the first throttle valve is large. The return oil is throttled by the valve. Next, when the pilot oil pressure decreases, the throttle of the return oil by the second throttle valve is gradually released in accordance with the decrease, the flow rate of the pilot oil is made uniform throughout the turning stop period, and a slower stop operation can be performed.

The turning operation circuit of the aerial work vehicle according to claim 3 is
A switching circuit for selecting between the operation delay and the normal stop operation according to claim 1 or 2, is provided.

By providing such a switching circuit, when it is desired to accurately adjust the position of the worktable, by canceling the delay operation, the worktable can be accurately positioned without any operation delay.

[0011]

FIG. 1 is a side view showing an embodiment of an aerial work vehicle to which a turning operation circuit according to the present invention is applied. In FIG. 1, reference numeral 1 denotes a crawler type traveling body, and the traveling body 1 may be configured as a wheel type. Reference numeral 2 denotes a revolving body mounted on the traveling body 1 via a revolving device 3, and 4 denotes a telescopic boom mounted on the revolving body 2 by a boom cylinder 6 with a boom foot pin 5 as a center. A bracket 4a is fixed to the distal end of the telescopic boom 4, and a work table 8 centered on a pin 7 is attached to the bracket 4a.
The mounting bracket 9 is mounted so as to swing vertically. A horizontal holding hydraulic cylinder 10 is mounted between the brackets 4a and 9, and the hydraulic cylinder 10 works with the boom cylinder 6 so that the worktable 8 is always horizontal. A work table 8 is provided between the bracket 9 and the work table 8.
Is provided with a turning device 11 for turning the turning force within a range of a predetermined angle. Reference numeral 12 denotes an operation panel mounted on the work table 8.

FIG. 2 shows a turning operation circuit according to the present embodiment. 3a is a turning motor of the turning device 3. 13,
Reference numeral 14 denotes a hydraulic pump and a pilot hydraulic pump mounted on the revolving unit 2, respectively. A control valve 15 and a flow control valve 1 are provided between the hydraulic pump 13 and the swing motor 3.
6, 17 and overload prevention valves 19 and 20 are provided.

Reference numeral 22 denotes a negative brake which is a spring type hydraulic cylinder attached to the hydraulic motor 3a. 23 is a control valve of the negative brake 22. 24
Is a turning pilot valve provided on the operation panel 12.
The pilot hydraulic pump 14 and an oil tank 25 are connected to the primary side of the pilot valve 24. On the secondary side of the pilot valve 24, a right turn pilot line 26 and a left turn pilot line 27 are provided, and these pilot lines 26 and 27 are respectively connected to the control valve 15 of the turn motor 3a. Connected to the operation units 15a and 15b.
Further, these pilot lines 26 and 27 are commonly connected to an operation section 23 a of the control valve 23 via a shuttle valve 29.

Each of the pilot lines 26 and 27 is provided with a throttle valve 30 for limiting the flow rate of the return oil of the pilot oil so as to slow down the operation when the turning is stopped. The throttle valve 30 of the present example includes a first throttle valve 31 and a second throttle valve 32 inserted in series between the throttle valve 31 and the pilot valve 24. The throttle amount is controlled by the pressure difference before and after the first throttle valve 31, and the throttle by the second throttle valve 32 is released in response to a decrease in the pressure of the return oil generated in the pilot lines 26 and 27. .

Each throttle valve 30 is provided with a bypass valve 34 provided with a check valve 33 for avoiding the throttle action of the throttle valve 30 at the start of turning. Further, the throttle valve 30 is provided with a bypass valve 36 having a stop valve 35 constituting a switching circuit for selecting an operation delay by the throttle valve 30 and a normal stop operation. An operating device (not shown) installed on the revolving superstructure 2 of the aerial work vehicle
Is provided mainly for checking the initial operation of the aerial work vehicle, and therefore does not perform the delay operation when the turning is stopped.

In this turning operation circuit, when the pilot valve 24 is operated so that the pilot oil is supplied to the right turning pilot line 26, the pilot hydraulic pump 14
Is supplied to the operating portion 15a of the control valve 15 through the check valve 33 on the pilot line 26 side, the control valve 15 is switched to the left position in the figure, and the swing motor 3a turns the swing body 2 clockwise. Operate in the direction to be performed. At the same time, the pilot oil in the pilot line 26 is supplied through the shuttle valve 29 to the operating portion 23 of the control valve 23.
a, the control valve 23 is switched to the left position in the figure, the pilot pressure oil from the pilot hydraulic pump 14 is supplied to the negative brake 22 via the control valve 23, the negative brake 22 is released, and the turning operation is performed. Is performed.

On the other hand, when the operating lever of the pilot valve 24 is returned to the original position, the control valves 15, 23 try to return to the intermediate position and the right position, respectively, due to the decrease in the hydraulic pressure of the pilot line 26. Here, initially, due to the residual pressure in the pilot line 26 and the like, the differential pressure before and after the first throttle valve 31 is in a large state, and the second throttle valve 32 is controlled so as to throttle the pilot line 26. 1, second throttle valve 3
The return oil to the oil tank 25 of the pilot line 26 is throttled by 1 and 32. Due to this restriction, the return oil has a small flow rate, the pressure in the pilot line 26 gradually decreases,
The control valves 15 and 23 are gradually switched. Therefore, the turning stop is smoothly performed, and it is possible to prevent a situation in which the worker on the work table 8 suddenly stops turning and the body shakes and collides with the frame around the work table 8. When the turning direction is reversed, the turning stop operation is performed slowly by the same operation.

If the above-mentioned turning stop is performed slowly, there is a tendency that the position setting of the work table 8 is not performed accurately. Therefore, when it is necessary to perform accurate positioning, the stop valve 35 is switched from the shut-off position (lower position) to the communication position (upper position) by switching the switch 37 provided on the operation panel 12 to switch the throttle valve. Eliminate the effects of 30.

In the above embodiment, the swing motor 3
3A and 3B, the operation delay in turning stop is performed for both the negative valve 22 and the negative brake 22. However, as shown in FIG. The pilot lines 26, 27 connected to the parts 15 a, 15 b by pilot lines 39, 40 and having the throttle valve 30 are connected to the negative brake 22.
Is connected only to the operation part 23a of the control valve 23 of FIG. In this case, only the negative brake 22 performs the delay operation when turning is stopped.

In the embodiment shown in FIG. 4, the secondary lines 41 and 42 of the pilot valve 24 are connected to the negative brake 2 through the shuttle valve 29 without passing through the throttle valve 30.
2, directly connected to the operation part 23a of the control valve 23,
The pilot pipes 26 and 27 having the throttle valve 30 are used to operate the operation parts 15a and 15b of the control valve 15 of the swing motor 3a.
Connected to. In this case, the swing motor 3a
Only for the turning stop, a delay operation is performed.

In the present embodiment, the impact at the time of turning stop is reduced by the throttle valve 30. However, even at the start of turning, an impact may be generated by a sudden operation. Therefore, the bypass valve 3 that bypasses the throttle valve 30
By removing 4, 36, the impact at the start of turning can be reduced.

[0022]

According to the first aspect, at least one of the turning motor of the turning device and each operation circuit of the negative brake thereof is stopped when the turning is stopped or the brake is applied by the negative brake. Since the operation delay circuit including the throttle valve for slowing down the rotation is provided, the turning is stopped slowly, the impact at the time of stopping the turning is reduced, and the workability on the work table is improved.

According to claim 2, according to claim 1, the throttle valve is inserted between the first throttle valve and the first throttle valve and the pilot valve, and Since the throttle valve is constituted by the second throttle valve whose throttle amount is controlled by the pressure difference between the front and rear sides, the flow of the pilot oil is made uniform throughout the turning stop, and a slower stopping operation can be performed.

According to the third aspect, in the first or second aspect, a switching circuit for selecting the operation delay and the normal stop operation is provided. By canceling the delay operation, the work table can be accurately positioned without any operation delay.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of an aerial work vehicle to which a turning operation circuit according to the present invention is applied.

FIG. 2 is an example of a turning operation circuit according to the present embodiment.

FIG. 3 is a turning operation circuit diagram of another embodiment of the present invention.

FIG. 4 is a turning operation circuit diagram according to another embodiment of the present invention.

[Explanation of symbols]

1: running body, 2: revolving body, 3: revolving device, 4: telescopic boom, 5: boom foot pin, 6: boom cylinder, 7:
Pin, 8: Work table, 9: Bracket, 10: Hydraulic cylinder for horizontal holding, 11: Swivel, 12: Operation panel, 13:
Hydraulic pump, 14: pilot hydraulic pump, 15, 2
3: control valve, 22: negative brake, 2
4: pilot valve, 26, 27: pilot line, 2
9: shuttle valve, 30: throttle valve, 31: first throttle valve,
32: second throttle valve, 33: check valve, 35: stop valve

Claims (3)

[Claims] 1. A revolving structure is installed on a traveling body via a revolving device, a telescopic boom is mounted on the revolving body so as to be able to move up and down, and a work table is mounted on a tip of the telescopic boom. A traveling body, a turning device, and an aerial work vehicle equipped with a telescopic boom operating device, wherein at least one of a turning motor of the turning device and each operation circuit of a negative brake thereof includes a turning motor when turning is stopped. A turning operation circuit for an aerial work vehicle, comprising: an operation delay circuit including a throttle valve for slowing down a brake application operation by a stop or a negative brake. 2. The operating circuit according to claim 1, wherein each operating circuit of the swing motor of the swing device and the negative brake thereof has a control valve for controlling them and a pilot hydraulic line connected to the control valve. The throttle valve has a first throttle valve provided in the pilot hydraulic line, and a second throttle valve connected in series to the first throttle valve.
The turning operation circuit of the aerial work vehicle, wherein a throttle amount of the second throttle valve is controlled based on a pressure difference between the front and rear of the first throttle valve. 3. The turning operation circuit for an aerial work vehicle according to claim 1, further comprising a control switching circuit for selecting the operation delay and a normal stop operation.