JPH0247085Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydraulic circuit for an outrigger hydraulic cylinder in a wheeled working machine such as a wheeled hydraulic excavator or a hydraulic truck crane.

[Conventional technology]

Fig. 3 is a side view of a wheeled hydraulic excavator to which the present invention is applied, and Fig. 4 is an enlarged rear view thereof.
and a lower traveling body (vehicle body) 20 having tires 23. An outrigger device 22 for stabilizing the vehicle body during work is attached to a track frame 21 in the lower traveling body 20, as shown in FIG.
They are provided at one location only at the rear end, or at two locations at the rear end and the center or at the rear end and front end. As shown in FIG. 4, the outriggers 22b are rotatably mounted around pins 22d at both left and right ends of an outrigger beam 22a fixed to the rear of the truck frame 21, and are rotated by the expansion and contraction of hydraulic cylinders 22c. It is becoming more and more common.

Figure 6 shows the hydraulic circuit of a conventional outrigger hydraulic cylinder that is equipped with outrigger devices at two locations, at the front and rear ends of the vehicle body, and all four hydraulic cylinders 22FL to 22RR are connected in parallel. ,
Control is achieved by supplying and discharging pressure oil from the hydraulic source 3 to two oil passages 9a and 9b passing through the center joint 5 by switching the directional switching valve 4. 10 is a hydraulic tank, 8a, 8
C and 8e are the confluence points of the bottom chamber side oil passages on the lower traveling body side, and 8b, 8d, and 8f are the confluence points of the rod chamber side oil passages.

In FIG. 6, when the directional control valve 4 is operated,
The hydraulic cylinders 22FL to 22RR start moving in the order of decreasing sliding resistance, and jack up the vehicle body after all outriggers touch the ground. Therefore, the front and rear outriggers cannot be operated independently. (In the case of an outrigger device only at the rear end, the left and right sides cannot be operated independently.) Figure 7 shows a device in which a directional control valve 4' and oil passages 9c and 9d are added to enable independent operation of the front and rear outriggers. This is a conventional hydraulic circuit.

[Problem that the invention attempts to solve]

However, this hydraulic circuit requires an additional directional valve 4', and also hydraulic cylinders 22RL,
Two oil lines 9c and 9d with high pressure and large flow rate to 22RR
It is necessary to add Since the additional oil passages 9c and 9d pass through the center joint 5, it is necessary to make the center joint 5 large. Therefore, it is unavoidable that there will be a significant cost increase, and making the hydraulic circuit shown in Figure 6 standard and adding front/rear or left/right independent operation functions as an option, that is, modifying it to the one shown in Figure 7, is not a good idea. This requires major changes to the switching valve and center joint, which poses a very difficult problem.

The purpose of the present invention is to provide a hydraulic circuit for an outrigger hydraulic cylinder that allows the front and rear or left and right outriggers to be operated independently by simply adding a small oil passage to the center joint. It is.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention includes an upper rotating body having a front attachment, a lower traveling body having tires, and rotatable mounting via hydraulic cylinders on at least the rear left and right sides of the lower traveling body. In a wheeled work machine equipped with an outrigger, a pilot type 3-port 2-position switching valve is connected to the confluence of the bottom chamber side oil passages or the confluence of the rod chamber side oil passages of the hydraulic cylinders connected in parallel, It is characterized in that the pilot oil passage to the switching valve is led to the upper revolving structure side via a center joint.

[Effect]

Since the present invention is configured as described above, pilot pressure oil is supplied to the pilot oil passage (small oil passage) passing through the center joint, and the oil pressure is used to control the bottom chamber side of the outrigger hydraulic cylinder on the lower traveling body side or By switching the pilot type 3-port 2-position switching valve installed at the confluence of the oil passages on the rod chamber side, the front and rear or left and right hydraulic cylinders can be selectively expanded and contracted, allowing the front and rear or left and right outriggers to be operated independently. can do.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in more detail with reference to FIGS. 1 and 2. In Figure 1, the same symbols as in Figure 6 are the same.
or something equivalent. Figure 1 shows the hydraulic circuit diagram of the outrigger hydraulic cylinder of the present invention, which is equipped with outrigger devices at two locations, at the front end and rear end of the vehicle body. Rod side oilway confluence point 8
A pilot type 3-port 2-position switching valve 6 is connected to b (located on the lower traveling body side), and a pilot oil passage 7 to the switching valve 6 is guided to the upper rotating body side through the center joint 5.

Next, the action will be explained. When no oil pressure is acting on the pilot oil passage 7, the switching valve 6 is in the position shown by the spring, so when the directional switching valve 4 is operated to the A position, the pressure oil from the hydraulic source 3 is transferred to the four hydraulic cylinders. It is simultaneously sent to the bottom chamber side of 22FL to 22RR. And rear outrigger hydraulic cylinder 2
The pressure oil on the rod chamber side of 2RL and 22RR is pushed out and flows to the hydraulic tank 10 through the switching valve 6, so that the rear outrigger can be moved. However, the front outrigger hydraulic cylinder 22FL~22
Since the oil passage on the FR rod chamber side is closed by the switching valve 6, the front outrigger does not move. When the directional switching valve 4 is operated to the RO position, pressure oil from the hydraulic source 3 is supplied only to the rod chamber side of the rear outrigger hydraulic cylinders 22RL and 22RR through the switching valve 6, so only the rear outriggers move and the front Outriggers don't move.

Next, pressure oil is supplied to the pilot oil passage 7, and the switching valve 6 is switched to the A position by the oil pressure. When the directional control valve 4 is operated in this state, only the front outriggers move and the rear outriggers do not move due to the same effect as described above. In other words, the front and rear outriggers can be operated independently. Incidentally, even if the switching valve 6 is connected to the confluence point 8a of the bottom chamber oil passages of the outrigger hydraulic cylinders 22FF to 22RR, the front and rear outriggers can be independently operated in the same manner as described above.

FIG. 2 is a hydraulic circuit diagram of an outrigger hydraulic cylinder showing another embodiment of the present invention in which an outrigger device is installed only at the rear end of the vehicle body. Hydraulic cylinders for left and right outriggers 22RL, 22RR
A pilot type 3-port 2-position switching valve 6 is connected to the confluence point 8c of the oil passages on the bottom chamber side (located on the lower traveling body side), and the pilot oil passage 7 to the switching valve 6 is connected to the upper rotating body side through the center joint 5. It is designed to lead to.

When pressure oil is not supplied to the pilot oil passage 7, the switching valve 6 is in the position shown in the figure, so when the directional switching valve 4 is operated, only the hydraulic cylinder 22RL expands and contracts, so only the left outrigger moves, and the right outrigger moves. It doesn't move. Next, pressure oil is supplied to the pilot oil passage 7, and the switching valve 6 is switched to the A position by the oil pressure. In this state, when the directional control valve 4 is operated, only the hydraulic cylinder 22RR expands and contracts.
Only the right outrigger moves, the left outrigger does not move. Therefore, the left and right outriggers can be operated independently.

In addition, the left and right outrigger hydraulic cylinders 22RL,
A pilot type 3-port 2-position switching valve 6 is connected to the confluence point 8d of the oil passages on the rod chamber side of the 22RR, and the pilot oil passage 7 to the switching valve 6 is configured to be led to the upper rotating structure side through the center joint 5. However, the left and right outriggers can be operated independently in the same manner as described above.

Figure 5 shows an application example of Figure 1, in which outrigger hydraulic cylinders 22FF to 22FF are connected in parallel.
A pilot type 3-port 2-position switching valve 6 is connected to the oil passage junctions 8b, 8c, and 8e on the rod chamber side and bottom chamber side of the 22RR, respectively, and the pilot oil passages 7a, 7b to these switching valves 6 are connected to the center joint. 5 to the upper rotating body side.

In this way, by using three switching valves and providing two pilot oil passages, each of the front, rear, left and right outriggers can be operated independently.

[Effect of idea]

As described above, according to the present invention, in a wheeled working machine consisting of an upper rotating body having a front attachment for work and a lower traveling body having tires, an outrigger device is provided at least at the rear end of the lower traveling body frame. A pilot type 3-port 2-position switching valve is connected to the confluence of the oil passages on the bottom chamber side or rod chamber side of the outrigger hydraulic cylinder, and the pilot oil passage to the switching valve is connected to the upper rotating structure side through the center joint. By installing a low-pressure, small-flow pilot oil passage in the standard center joint, the left and right outriggers can be operated independently with a simple modification of adding an inexpensive switching valve and its operating oil passage. It has the advantage of being able to add functions that allow you to do this.

[Brief explanation of drawings]

Figures 1 and 2 are hydraulic circuit diagrams of an outrigger hydraulic cylinder showing one embodiment of the present invention, Figure 3 is a side view of a wheeled hydraulic excavator as an example of a machine to which the present invention is applied, and Figure 4 is a side view of a wheel-type hydraulic excavator. Fig. 3 is an enlarged rear view showing the mechanism of the outrigger device, Fig. 5 is a hydraulic circuit diagram of an outrigger hydraulic cylinder showing an application example of the present invention, and Figs. 6 and 7 are hydraulic pressure of a conventional outrigger hydraulic cylinder. It is a circuit diagram.

Claims (1)

[Scope of utility model registration request] A wheeled working machine comprising an upper revolving body having a front attachment, a lower traveling body having tires, and outriggers rotatably attached to at least the rear left and right sides of the lower traveling body via a hydraulic cylinder, A pilot type 3-port 2-position switching valve is connected to the confluence point of the bottom chamber side oil passages or the confluence point of the rod chamber side oil passages of the hydraulic cylinders connected in parallel, and the pilot oil passage to the switching valve is connected to the center joint. A hydraulic circuit of a hydraulic cylinder for an outrigger, characterized in that the hydraulic cylinder is led to the upper rotating body side through the.