JPS5941262Y2 - Overload prevention device for hydraulic drilling machine - Google Patents

Description

[Detailed Description of the Invention] This invention is designed to prevent overload occurring through the arm during the turning operation of an oil hydraulic excavator having an arm that extends and retracts in multiple stages.

In a deep drilling oil excavator that has an arm that extends and retracts in multiple stages, if the upper revolving structure rotates with the arm extended and the packet at the tip hits the excavation side wall, the extended arm If the length is longer than a predetermined length, the arm acts as a lever and applies unreasonable external force to various parts of the excavator, such as the arm and poom, which may lead to damage or other malfunctions.

Conventionally, devices to prevent this have only been used to detect the contact load on the side wall during turning and to moderate the turning force.

In contrast, this invention is configured such that the multi-stage telescoping arm cannot be rotated once it has been extended to a predetermined length, so as not to strain the various parts of the excavator. To explain FIGS. 1 to 4, as shown in FIG. 1, an upper rotating body 2 is mounted on a lower traveling body 1 so as to be able to rotate freely, and a poom sill is placed in front of the upper rotating body 2. 4 is pivoted.

An outer arm 6 that is rotated by an arm cylinder 5 is pivotally supported at the tip of the poom 4, and inside thereof, a middle arm 7 and an inner arm 8 are sequentially connected to a middle arm telescopic cylinder (not shown) and an inner arm telescopic cylinder. 9 (FIG. 2), it is telescopically attached so that it can expand and contract.

Note that 10 is a pin that supports the base end of the inner arm telescopic cylinder 9, and 7a is a stopper provided on the middle arm 1.

In this invention, an actuator such as a band-shaped plate 8a is further attached to the upper end outer plate of an inner arm such as the middle arm 7 or the inner arm 8, which will be described later, to be fitted into the outer arm, which will be described later. A limit switch 12 is attached to the lower end of the outer arm such as the middle arm 7 via a bracket 11, and this switch is connected to the plate 8.
The solenoid valve 19 is configured to be actuated by coming into contact with the solenoid valve 19.

13 is a packet attached to the lower end of the inner arm 8.

Therefore, the -f non-arm 8 (or middle arm 1) is lowered and the contact of the seat switch 12 rides on the plate 8a.In 1, the electric circuit is open, but the contact is stuck on the plate 8a.
The electric circuit is closed when the limit switch 12 is activated.

FIG. 4 shows a hydraulic circuit diagram of the present invention, which is connected to a hydraulic pump 17 via a hydraulic motor 14/Ii, a brake valve 15, and a switching valve 16.

A solenoid valve 19 is provided in a branch circuit branching from between the brake valve 15 and the switching valve 16, and the solenoid valve 19 is opened by the limit switch 12.

Since this invention has the above-described structure, when the first multi-stage telescoping arm is rotated with a length shorter than a predetermined length, the limit switch 12 does not operate and the solenoid valve 19 does not operate.

For this purpose, the oil from the hydraulic pump 17 is supplied to the hydraulic motor 14 via the switching agent 6 and the brake valve 15 to cause it to rotate (rotate).

At this time, the solenoid valve 19 is shut off, and the supply pipe and return pipe connecting the switching valve 16 and the brake valve 15 are not communicated with each other, so that normal turning is possible.

Next, when the telescoping arm extends to position 1, which is longer than a predetermined length, the limit switch 12 is activated and the solenoid valve 19 is opened. It is supplied to the brake valve 15 and flows directly into the return line 9 via the solenoid valve 19.

However, since the oil supplied to the solenoid valve 19 has almost no resistance to the solenoid valve 19, almost all of the oil produced from the switching valve 16 returns directly to the tank 18 via the switching valve 19.
The hydraulic circuit of the hydraulic motor 14 does not get wet.

Therefore, the oil momome 14 cannot rotate (turn).

As mentioned above, in this invention, the multi-stage telescoping arm can rotate as long as it is shorter than a predetermined length, but when the arm reaches a predetermined length or more, the displacement of this arm is detected and the rotation motor is activated. Since the supply of oil to the excavator is cut off, it is possible to prevent abnormal forces from acting on each part of the excavator, such as the arm or boom, and prevent accidents such as damage to the arm or boom or falling of the excavator itself. can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an overall view, FIG. 2 is a vertical sectional view of essential parts, FIG. 3 is a cross-sectional view thereof, and FIG. 4 is a hydraulic circuit diagram. Codes in the figure: 2 is the upper revolving body, 6/l'i is the outer arm, 7 is the middle arm, 8 is the inner arm, 124d
limit switch, 14 is a hydraulic motor, 16 is a switching valve,
19 indicates a solenoid valve.

Claims (1)

[Scope of utility model registration request] A detection device such as a limit switch that operates according to the extension of the arm is attached to the outside of the lower end of the outer arm of an oil mower excavator that has an arm that extends and contracts in multiple stages, and is placed at a position corresponding to the detection device on the outside of the upper part of the inner arm. In addition to providing an actuator,
A switching mechanism such as a solenoid valve that is switched by the detection device is provided in the hydraulic circuit connected to the swinging device of the hydraulic excavator, and the supply of hydraulic oil to the swinging device is cut off while the detection device is in operation. Overload prevention device for oil mower excavators.