JPS6048440B2 - Work platform storage device for aerial work vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in a work platform that is attached to the tip of a boom installed in an aerial work vehicle for performing aerial work, and particularly to a safe storage device thereof.

Traditionally, aerial work vehicles have been equipped with a telescoping boom on the vehicle body, a work platform is attached to the tip of the boom, and the work platform can be moved to any height by extending/retracting the boom, turning, and raising/elevating the boom. A structure that allows work at heights has been put into practical use.

By the way, this type of aerial work vehicle is generally constructed so that the work platform attached to the tip of the boom is always maintained horizontally regardless of changes in the elevational state of the boom so that workers can work safely on it. Even when the boom is retracted and placed in a retracted position, the workbench is held horizontally, taking up wasted space and generally being in a high position, resulting in a lack of operational safety. I was getting used to it. Therefore, in the industry, in the working position, the workbench is always held horizontally as in the past, so that work can be done safely, and in the retracted position, work can be done compactly and safely by cleverly utilizing the space above the vehicle body. A storage device for the machine has been requested for a long time. The present invention answers this need, and embodiments of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes the body of the aerial work vehicle, 2 a support stand pivotally mounted to the rear of the vehicle body 1 so as to be able to rotate horizontally, and 3 a boom whose base end is pivoted to the support stand 2 so as to be able to move up and down. The main boom 4 consists of a telescopic main boom 4 in the form of a cylinder, and a sub-boom 5 pivoted to the tip of the main boom 4 so that it can be folded horizontally along the main boom 4. A hydraulic cylinder 6 is interposed to raise and lower the boom 3.

Further, the sub-boom 5 is extended over the main boom 4 via a hydraulic cylinder (not shown) equipped with a link mechanism, and is folded sideways, but the connecting portion between the sub-boom 5 and the main boom 4 is Since the specific structure in is not the gist of the present invention, it will be omitted for the sake of simplification. And 7 is the workbench and the secondary boom 5
It is pivotally connected vertically via a mounting member 8 having a crank 8' at its tip, and the tip of the sub-boom 5 and the crank 8 are
A balance cylinder 9 is interposed between them to hold the workbench 7 horizontally and to fold and rotate it. That is, a sensing cylinder 10 for sensing the up-down state of the main boom 4 is interposed between the base of the main boom 4 and the support base 2, and the head side of this sensing cylinder 10 and the head side of the balance cylinder 9 are reversed. A connection interposed in the middle of the safety valve mechanism 11 consisting of a stop valve 11' and a relief valve 11'' communicates with each other through a pipe 12, and connects the rod side of the sensing cylinder 10 and the rod side of the balance cylinder 9 with a connecting pipe 13. Here, the connecting pipe 12
and 13 constitute an interlocking circuit for the balance cylinder 9 and the perturbation cylinder 10. Further, branch pipes 14 and 15 are provided from the middle of each connecting pipe 12 and 13, respectively, and each branch pipe 14 and 15 is connected to a Ξ position switching valve 18 through on-off valves 16 and 17, respectively. This switching valve 18 is connected to a pressure oil circuit 19 consisting of a pump, a tank, etc. A safety valve 20 is provided from the middle of the connecting pipe 13 via a branch pipe 21, and this safety valve 20 is also connected to the pressure oil circuit 19.

Since the present invention is configured as described above, as shown in FIG. 3, when the boom 3 moves upward and its elevation angle α with respect to the horizontal plane increases, the sensing cylinder 10 is extended as the boom 3 moves upward, and pressure is applied from the rod side. Oil is sent to the rod side of the balance cylinder 9 through the connecting pipe 13, contracts the balance cylinder 9, and rotates the work platform 7 downward so that its inclination angle β with respect to the sub-boom 5 decreases to a horizontal state. Retention. do. Conversely, if the boom 3 moves downward and the elevation angle α decreases, the detection cylinder 10 contracts as the boom 3 moves downward, and pressure oil flows from the head side through the connecting pipe 12 and the check valve 11'. is sent to the head side of the balance cylinder 9, and the balance cylinder 9
- Rotate the worktable 7 upward so that the angle of inclination β increases and hold it in a horizontal state. In FIG. 3, the workbench 7 is rotated by the balance cylinder 9 which is interlocked with the sensing cylinder 10 that senses the elevation and elevation of the boom 3 so that α+β=180 degrees at all times. In addition, the workbench 7 can be retracted/positioned.
To release the horizontal state and rotate it downward, open the on-off valves 16 and 17, and then operate the switching valve 18 to forcibly transfer pressure oil from the pressure oil circuit 19 to the rod of the balance cylinder 9. This is done by introducing it into the side, which will be described in detail later. That is, when changing from the working position to the retracted position, the main boom 4 is retracted and lowered to a substantially horizontal position, and the sub-boom 5 is moved sideways along with the main boom 4 via a hydraulic cylinder (not shown). Fold into. Even in this state, the workbench 7 is maintained in a horizontal state (dotted line (position) in Figure 1), so open the on-off valves 16 and 17 and operate the switching valve 18 to the right position (upper position in Figure 2). Pressure oil is introduced from the pressure oil circuit 19 to the rod side of the balance cylinder 9 through the branch pipe 15 and the connecting pipe 13, and the work platform 7 is rotated downward until it is approximately perpendicular to the sub-boom 5. Close the folding on-off valves 16 and 17 and switch on the switching valve 1.
8 is returned to the neutral position and stored. In addition, the branch pipe 15 and the connecting pipe 13 are connected to the pressure oil circuit 19 via the switching valve 18.
The pressure oil introduced into the main boom 4 is also sent to the control cylinder 10, but in the retracted position, the main boom 4 is firmly supported against the support base 2 by the hydraulic cylinder 6, and the control cylinder 10 is in a locked state. Therefore, pressure oil is introduced only into the balance cylinder 9. Next, when changing to the working position, open the on-off valves 16 and 17 in the reverse order of the above, operate the switching valve 18 to the left position (upper part of Figure 2), and transfer the pressure oil from the pressure oil circuit 19 to the branch pipe. 14 and the connecting pipe 12 to the head side of the balance cylinder 9, and the workbench 7 is rotated upward to bring it into a horizontal state, the on-off valves 16 and 17 are closed, and the switching valve 18 is returned to the neutral position.
After the sub-boom 5 is extended and fixed on the extension of the main boom 4, the main boom 4 is extended/contracted, rotated, and raised/raised.
The workbench 7 is appropriately moved to an elevated work position. By the way, the above explanation of setting the workbench 7 in the working position is for the case where the procedure is carried out according to the normal procedure, and next, the case where the operation is erroneously performed will be explained.

That is, when the main boom 4 is raised and lowered with the on-off valves 16 and 17 closed and the workbench 7 kept in the retracted position, the sensing cylinder 10 is extended accordingly, and the pressure on its rod side is reduced. Oil tries to be sent to the rod side of the balance cylinder 9 through the connecting pipe 13, but since the balance cylinder 9 is in a contracted state, the pressure oil cannot be sent, and if the main boom 4 continues to move up and down, the pressure oil is If no countermeasures are taken due to abnormally high pressure, any one of the connecting pipe 13, balance cylinder 9, and sensing cylinder 10 will be damaged.

In the present invention, the safety valve 20 is provided in the middle of the connecting pipe 13 via the branch pipe 21, so if the set pressure is set appropriately, the pressure oil will flow through the branch pipe 21 and the safety valve 20 to the pressure oil circuit 19. The work platform 7 is returned to the tank without changing its inclination angle with respect to the secondary boom 5 (approximately 9 in the retracted position).
It will only rise (maintained at 0 degrees) and will not cause any damage even if operated incorrectly. In the above embodiments, the workbench 7 is attached to the tip of the sub-boom 5 that can be folded horizontally, but even if the entire boom is of a telescoping type, the workbench 7 can be folded horizontally. The present invention can be applied as long as it rotates within a range that does not interfere with the vehicle body 1.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; Fig. 1 is an overall front view of the aerial work vehicle, Fig. 2 is an explanatory system diagram of the main parts, and Fig. 3 shows the rotation of the work platform and the elevation and elevation of the boom. It is an explanatory diagram showing an interlocking relationship. 3...Boom, 4...Main boom, 5.
...Secondary boom, 7...Workbench, 9...
... Balance cylinder, 10' ... Sensing cylinder, 12 ... Connection pipe, 13 ... Connection pipe, 20 ... Safety valve.

Claims (1)

[Scope of Claims] 1. A workbench rotatably attached to the tip of the boom, a sensing cylinder that senses the up-and-down state of the boom, and a balance cylinder that works in conjunction with the sensing cylinder to keep the workbench horizontal at all times. In the aerial work vehicle, a safety valve is interposed in the interlocking circuit of the balance cylinder and the sensing cylinder to prevent the work platform from rotating further in the storage direction from the storage position. Workbench storage device. 2. The above-mentioned boom is configured with a main boom that is freely extendable and retractable, and a sub-boom that is pivotably attached to the tip of the main boom and that can be folded horizontally, and the work platform is pivotably attached to the tip of the sub-boom. A work platform storage device for an aerial work vehicle according to claim 1.