JPH0444683Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The invention is applicable to working machines that utilize the main body of a hydraulic excavator, especially working machines that are equipped with a clam shell as an attachment and perform excavation work such as caisson digging. This relates to the attitude control circuit of the attachment.

[Prior Art] FIG. 2 shows an example of a working machine equipped with a clamshell on the main body of a hydraulic excavator.

In the figure, 1 is the working machine body, 2 is the upper revolving structure, and 3
indicates the undercarriage.

A hoisting boom 5 is attached to the upper revolving structure 2 so as to be able to be hoisted and raised by a hoisting cylinder 4.
A telescope boom 6 is tiltably provided at the tip of the telescope boom 6, a tilting cylinder 7 is attached between the telescope boom 6 and the undulating boom 5, and a clam shell 8 is suspended from the tip of the telescope boom 6.

When performing excavation work such as digging a caisson using such a work machine, the tilting cylinder 7 must be operated so that the telescope boom 6 is always in a vertical position. Conventionally, this work had to be done manually by the operator. The tilting cylinder 7 was operated to maintain the vertical posture of the telescope boom 6.

[Problems to be solved by the invention] As mentioned above, in the conventional posture maintenance of the telescope boom 6, the operator visually determines the posture of the telescope boom, and then manually controls the tilting cylinder 7 with a lever. Since the telescope boom was operated in a vertical position, it was difficult to operate and work efficiency depended on the skill of the operator.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present invention attempts to ensure that the telescope boom (clamshell attitude) can always maintain a vertical state regardless of the attitude of the hoisting boom. A tilting cylinder is provided between an attachment provided at the tip of the hoisting boom and the hoisting boom, the tilting cylinder is connected to a hydraulic power source via a directional control valve, and communication between the two is cut off between the directional control valve and the tilting cylinder. The present invention is characterized in that an attitude control valve is provided, and in the cutoff position of the attitude control valve, both oil chambers of the tilting cylinder are short-circuited and communicated with a tank.

[Operation] When the attitude control valve is set to the blocking position, the tilting cylinder is in a substantially free state, and is transferred to and held in the attitude determined by the weight of the attachment. When the attitude control valve is set to the communicating position, the tilting cylinder is driven by the directional control valve. can be done.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention.

The tilting cylinder 7 is connected to a hydraulic pump 10 and a tank 11 via a directional valve 9 . An attitude control switching valve 12 is provided between the tilting cylinder 7 and the directional switching valve 9.
will be established. A load circuit 17 in which a check valve 15 and a relief valve 16 are connected in parallel between the attitude control switching valve 12 and the rod side oil chamber 13 of the tilting cylinder 7, and a speed in which a check valve 18 and a throttle valve 19 are connected in parallel. An adjustment circuit 20 is provided. In addition, the attitude control switching valve 12 is a two-position switching valve as shown in the figure, and in the a position, it simply communicates the tilting cylinder 7 and the direction switching valve 9, but in the b position, both oil chambers of the tilting cylinder 7 communicate with each other. 13 and 14 are short-circuited, and the short-circuited oil passage is connected to the tank 11. In addition, the attitude control switching valve 12 and the tank 11
A load circuit 23 in which a check valve 21 and a relief valve 22 are connected in parallel is provided between the two.

In the figure, 24 is an engine for driving the hydraulic pump 10, and 25 is a main relief valve.

The operation of the circuit will be explained with reference to FIG.
First, in order to shift from the state shown in FIG. 2A to the digging position B, the attitude control switching valve 12 is set to the a position, the luffing cylinder 4 is operated, and the tilting cylinder 7 is operated by operating the directional switching valve 9 to move the clam shell 8. Align to the excavation location. Next, the directional control valve 9 is set to the neutral position (hydraulic pump 10 and tank 11 are short-circuited), and the attitude control valve 12 is switched to b.
position. In this state, both oil chambers 13 and 14 of the tilting cylinder 7 are short-circuited and connected to the tank 11, so the tilting cylinder 7 is in a so-called free state in which it can move freely according to the load state. Therefore, the weight of the clam shell 8 urges the telescope boom 6 so that its axial center line is oriented in the vertical direction. Here, as shown in the figure, the connection point between the telescope boom 6 and the hoisting boom 5 is located at a position deviated from the telescope boom axis, and therefore a moment due to the eccentricity of the connection point acts on the telescope boom 6. When there is no resistance to the tilting of the telescope boom 6, the telescope boom 6 stands still in a slightly tilted state.

Therefore, in this embodiment, as described above, the load circuit 1
7 and 23 are provided so as to generate a reaction force in the tilting cylinder 7 sufficient to counter the moment due to the eccentric support of the telescope boom.

That is, when a force on the rod extension side is applied to the tilting cylinder 7 due to a moment due to eccentric support, the oil in the rod side oil chamber 13 flows into the head side oil chamber 14 through the load circuit 17 and the speed adjustment circuit 20. However, the insufficient amount of oil is further sucked out from the tank 11. Due to the action of the load circuit 17, the rod side oil chamber 1
3 is maintained at the relief pressure of the relief valve 16, and a reaction force is generated in the tilting cylinder 7. or,
When a compression force is applied to the rod, oil in the head oil chamber 14 flows into the rod oil chamber 13 and excess oil is discharged to the tank 11 through the load circuit 23. During this oil discharge operation, the hydraulic pressure in the head side oil chamber 14 is maintained at the relief pressure of the relief valve 22, producing a reaction force in the tilting cylinder 7 as described above.

The speed adjustment circuit 20 is for adjusting the tilting speed of the telescope boom 7. For example, when the attitude control valve 12 is switched from the A position in FIG. 2 to the B position, the telescope boom 6 may move too rapidly. This is to prevent it from tilting.

When the telescope boom 6 becomes vertical, the attitude control valve 12 is switched to the a position and the direction control valve 9 is set to the neutral position, thereby blocking the tilting cylinder 7 and maintaining the vertical state of the telescope boom 6.

As described above, no special operation is required to bring the telescope boom 6 into the vertical state, and it is sufficient to simply switch the attitude control valve 12.

It goes without saying that if the connection point between the hoisting boom 5 and the telescope boom 6 can be aligned with the axis of the telescope boom, the load circuit in the circuit becomes unnecessary.

Furthermore, it goes without saying that this embodiment can be applied to all cases where the attitude of the attachment can be modified depending on its weight, other than when a clam shell is installed as an attachment.

[Effects of the Invention] As described above, according to the present invention, the attitude of the attachment can be changed by simply switching the attitude control valve, which greatly facilitates the attitude control operation and improves work efficiency.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram showing one embodiment of the present invention;
FIG. 2 is an explanatory diagram of a working machine equipped with a clam shell. 5 is a luffing boom, 6 is a telescope boom, 7 is a
1 is a tilting cylinder, 8 is a clam shell, 9 is a directional switching valve, and 12 is a posture control switching valve.

Claims (1)

[Scope of utility model registration request] A tilting cylinder is provided between an attachment provided at the tip of the hoisting boom and the hoisting boom, and the tilting cylinder is connected to a hydraulic power source via a directional control valve, and posture control is performed to disconnect communication between the two between the directional control valve and the tilting cylinder. 1. A posture control circuit for an attachment in a working machine, characterized in that the circuit is provided with a valve, and is configured such that both oil chambers of a tilting cylinder are shortened and communicated with a tank when the posture control valve is in a cutoff position.