JPH0545517B2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a lifting device hydraulic circuit for an aerial work vehicle, and more specifically, if an abnormal condition occurs and the battery is still alive, the work platform can be safely moved by the operation of a worker on the work platform. This relates to the hydraulic circuit for lowering.

Prior Art When a vehicle for working at heights is working at high places, when a problem occurs with the engine or pump, which is the hydraulic pressure source for the lifting hydraulic circuit, an emergency electric pump is activated to lower the work platform. was. In addition, in the case of an aerial work vehicle that is not equipped with an emergency electric pump, a drain pipe that communicates with the hydraulic oil tank is provided in the undulation cylinder and telescopic cylinder of the aerial work vehicle, and an on-off valve is provided in the drain pipe. By manually opening the on-off valve, both cylinders were retracted and the work platform was lowered.

However, the operation of these emergency electric pumps and the on-off valves were performed on the vehicle body side, that is, on the ground side. Therefore, if there is no worker on the ground, the worker on the workbench cannot get down to the ground, so it is necessary to always have one person on the ground waiting to monitor the work.

Purpose This invention was made in order to solve the above-mentioned problems, and its purpose is to prevent the work platform from being removed by the operation of the worker on the work platform when the above-mentioned trouble occurs with the vehicle for working at height. This system enables lowering and lowering of high-altitude work vehicles safely to the ground, reducing the number of personnel by eliminating the need for a supervisor who was always required with conventional equipment, and reducing costs by eliminating the need for an emergency electric pump. The equipment is to provide hydraulic circuit.

Structure of the Invention In order to achieve the above object, the present invention includes a first control solenoid valve connected to a cylinder bottom chamber and a cylinder rod chamber of a telescopic cylinder, respectively, and a first control solenoid valve connected to a cylinder bottom chamber and a cylinder rod chamber of an undulating cylinder, respectively. a second control solenoid valve, a bypass pipe connecting the cylinder rod chamber of the telescopic cylinder and the cylinder bottom chamber of the undulating cylinder, and a first direction control solenoid valve provided in the bypass pipe; a first drain pipe connected to the cylinder bottom chamber of the telescoping cylinder; a second directional control solenoid valve provided in the first drain pipe; connected to the cylinder rod chamber of the undulating cylinder;
An introduction pipe that supplies hydraulic oil to the rod chamber when the rod chamber becomes a negative pressure state, a third directional control solenoid valve provided in the introduction pipe, and the first and second solenoid valves provided in the introduction pipe when an abnormal condition occurs. and an operating switch provided on the work platform that is raised and lowered by the operation of the telescopic and undulating cylinders in order to switch and control the third directional control solenoid valve. This is a summary.

Embodiment Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings.

Figure 1 shows a vehicle for high-altitude work, with body frame 1
A swivel base 2 is attached to the swivel base 2, which can rotate in the horizontal direction.
A is rotatably connected to the boom 3, and a workbench 4 is attached to the tip 3b of the boom 3. A telescopic cylinder 5 for extending and retracting the boom 3 is attached to the base end 3a side of the boom 3. A hoisting cylinder 6 for hoisting the boom 3 is provided between the boom 3 and the swivel base 2. and,
The work table 4 is configured to be moved up and down by the operation of both cylinders 5 and 6.

Next, the telescopic cylinder 5 and the undulating cylinder 6
The hydraulic circuit that controls this will be explained with reference to FIG.

The hydraulic circuit includes a hydraulic oil tank T, a filter F, a hydraulic pump P, and an engine E that drives the hydraulic pump P as a hydraulic source, and the hydraulic pump P is connected to the telescopic cylinder 5 via a first control solenoid valve 11. It is also connected to the undulation cylinder 6 via the second control solenoid valve 12.

The first and second control solenoid valves 11 and 12 are switched and driven by energizing the respective solenoids 11a, 11b, 12a and 12b, and control the operations of the telescopic and undulating cylinders 5 and 6, respectively. An operation switch (not shown) for controlling the excitation of each of the solenoids 11a to 12b is provided in the operating device on the workbench 4.

The cylinder rod chamber 5b of the telescopic cylinder 5 and the cylinder bottom chamber 6a of the undulating cylinder 6 are connected via a bypass pipe 17, and the bypass pipe 17 is provided with a first directional control solenoid valve 18. There is. The first directional control solenoid valve 18 is an operation switch (not shown) provided in the operating device of the workbench 4 separately from the operation member for switching the first and second control solenoid valves 11 and 12, respectively. 1), the solenoid 18a is energized and the hydraulic oil in the cylinder bottom chamber 6a of the undulating cylinder 6 is switched to be sent to the cylinder rod chamber 5b of the telescopic cylinder 5.

On the other hand, the cylinder bottom chamber 5a of the telescopic cylinder 5
A first drain pipe 19 whose other end communicates with the hydraulic oil tank T is connected to the drain pipe 19, and a second drain pipe 19 is connected to the drain pipe 19.
A direction control solenoid valve 20 is provided. or,
The cylinder rod chamber 6b of the undulation cylinder 6 also has an introduction pipe 21 communicating with the hydraulic oil tank T.
are connected to each other, and the introduction pipe 21 is provided with a third directional control solenoid valve 22 . The second and third direction control solenoid valves 20 and 22 are connected to the workbench 4.
The first directional control solenoid valve 18 provided in the operating device of
An operating switch (hereinafter referred to as a first operating switch) that switches between the two solenoids 20a and 22a is energized and switched to open the conduit.

A second drain pipe 23 is connected to the telescopic cylinder 5 side of the bypass pipe 17 with the first directional control solenoid valve 18 as a boundary;
A fourth directional control solenoid valve 24 is provided. This fourth directional control solenoid valve 24 is opened based on the operation of an operation switch (hereinafter referred to as a second operation switch), which is not shown and is separate from the first operation switch provided in the driving device, and the undulation cylinder 6 bypass pipe line 17 from the cylinder bottom chamber 6a of
The hydraulic oil sent through is discharged into the hydraulic oil tank T.

Next, the operation of the hydraulic circuit configured as described above will be explained.

Now, as shown in FIG. 1, the workbench 4 with a worker on it is at a high position, and while work is being carried out at that high position, for example, the first and second control electromagnetic Each solenoid 11a to 12b of the valves 11 and 12
When an abnormality occurs such as inoperability of the engine E, failure of the pump P, etc., the work platform 4 is lowered to the ground based on the normal switching operation of the first and second control solenoid valves 11 and 12. If this is not possible, the worker on the workbench 4 can operate the first operation switch for switching the first, second, and third directional control solenoid valves 18, 20, and 22 provided on the driving device. .

That is, when the first operating switch is operated and each solenoid 18a, 20a, 22a is excited and each direction control solenoid valve 18, 20, 22 is switched and opened, the cylinder bottom chamber 6a of the undulating cylinder 6 is opened.
The hydraulic oil is in the cylinder rod chamber 5 of the telescopic cylinder 5.
At the same time, the hydraulic oil in the cylinder bottom chamber 5a of the telescopic cylinder 5 is discharged to the hydraulic oil tank T. As a result, the telescopic cylinder 5 and the undulating cylinder 6 contract, and the work platform 4 moves to the swivel platform 2.
Descend while approaching the side.

At this time, the undulation cylinder 6 contracts and the inside of the cylinder rod chamber 6b of the same cylinder 6 becomes a negative pressure state, but a part of the hydraulic oil in the cylinder bottom chamber 5a of the telescopic cylinder 5 is directly and in the hydraulic oil tank T. Since oil is sent into the cylinder rod chamber 6b via the third directional control solenoid valve 22, the undulating cylinder 6 is smoothly contracted.

Further, when the contraction cylinder 5 completely contracts before the undulation cylinder 6 and the contraction operation of the undulation cylinder 6 stops, the worker on the workbench 4 performs the second operation of the fourth directional control solenoid valve 24. Operate the switch to open the control solenoid valve 24. At this time, the hydraulic oil in the cylinder bottom chamber 6a of the undulation cylinder 6 is discharged into the hydraulic oil tank T, and the undulation cylinder 6 starts its contraction operation again. Therefore, the work platform is safely and reliably lowered to the ground by the operator's own operation without the help of a ground supervisor, and the operator can descend to the ground by himself. Does not require electric pump.

In the above embodiment, when the telescopic cylinder 5 is completely contracted before the undulating cylinder 6, the fourth directional control solenoid valve 24 is provided in order to cause the undulating cylinder 6 to further contract. As shown in Figure 3, the first and fourth directional control solenoid valves 1
8 and 24 may be implemented as one directional control solenoid valve 25. In this case, when the first operation switch is operated, the solenoid 25a is energized to open the pipe 17 to the cylinder rod chamber 5b of the telescopic cylinder 5, and when the second operation switch is operated, the solenoid 25b is energized and activated. The pipe line 23 to the oil tank T will be opened.

Effects of the Invention As detailed above, the present invention connects the cylinder rod chamber of a telescoping cylinder and the cylinder bottom chamber of an undulating cylinder by a bypass pipe, and connects a first drain pipe to the cylinder bottom chamber of the telescoping cylinder.
An introduction pipe is provided in the cylinder rod chamber of one of the undulating cylinders, and first to third directional control solenoid valves are provided in each of these pipes, and these first to third directional control solenoid valves are installed on the workbench. By installing an operation switch that switches and controls the
In the event of engine or pump failure, a worker on the workbench operates the operation switch to ensure that the piston rod of the telescoping and undulation cylinder retracts, and the workbench receives help from a ground observer. The robot can safely descend to the ground without any trouble, and workers can get down to the ground on their own, reducing the number of workers. Further, since there is no need for an emergency electric pump and all operations are performed smoothly as long as the battery is alive, it is possible to reduce manufacturing costs and labor costs for workers.

[Brief explanation of the drawing]

FIG. 1 is an overall side view of a vehicle for working at high places, FIG. 2 is a hydraulic circuit diagram of a lifting device, and FIG. 3 is a hydraulic circuit of a main part of a lifting device showing another example of the present invention. Telescopic cylinder...5, Lifting cylinder...6, Cylinder bottom chamber...5a, 6a, Cylinder rod chamber...5b, 6b, First control solenoid valve...1
1. Second control solenoid valve...12, Bypass pipe line...17, First directional control solenoid valve...18, First drain pipe...19, Second directional control solenoid valve... ...20, introduction pipe...21, third directional control solenoid valve...22, second drain pipe...23, fourth directional control solenoid valve...24.

Claims (1)

[Scope of Claims] 1. A first control solenoid valve connected to the cylinder bottom chamber and cylinder rod chamber of the telescopic cylinder, respectively, and a second control solenoid valve connected to the cylinder bottom chamber and cylinder rod chamber of the undulating cylinder, respectively. a valve; a bypass conduit connecting the cylinder rod chamber of the telescopic cylinder and the cylinder bottom chamber of the undulation cylinder; a first directional control solenoid valve provided in the bypass conduit; and a cylinder bottom chamber of the telescopic cylinder. a first drain pipe connected to the first drain pipe; a second directional control solenoid valve provided on the first drain pipe; and a second directional control solenoid valve connected to the cylinder rod chamber of the undulation cylinder, when the rod chamber is in a negative pressure state. An introduction pipe for supplying hydraulic oil to the rod chamber, a third directional control solenoid valve provided in the introduction pipe, and switching between the first, second and third directional control solenoid valves when an abnormal condition occurs. A hydraulic circuit for a lifting device in an aerial work vehicle, comprising an operation switch provided on a work platform that is raised and lowered by the operation of the telescoping and raising and lowering cylinders for control.