JPH0415805Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an operating device for a hydraulic power shovel.

Prior Art In a conventional power shovel, each cylinder is stopped at the end of its stroke by interference between the cylinder and the piston, and a cushioning function is provided by restricting the hydraulic pressure at the end of the stroke. Further, the expansion and contraction of each cylinder was performed by each operating valve.

Problems to be Solved by the Invention In the conventional cushion function described above, if the operating lever is further moved at the end of the stroke, the hydraulic pressure is relieved and energy loss occurs. Furthermore, even if there were obstacles within the operating range of the work equipment, the cylinder device had to be controlled by lever operation each time.

Means and Effects for Solving the Problems The present invention was developed in view of the above-mentioned problems, and includes a pilot circuit that connects the control valves and the valves that operate the boom cylinder, arm cylinder, and bucket cylinder of the power shovel. , an electromagnetic switching valve is installed to short-circuit these pilot circuits, and a position detector such as a potentiometer is installed at each pivot point of the boom, arm, and bucket to detect the rotation angle of each of these members. Each of these attitude detectors is connected to the actuating part of the electromagnetic switching valve through a controller, and the attitude of the boom, arm, and bucket as they rotate through a predetermined angle is determined by the attitude detector. The detected value switches the electromagnetic switching valve installed in the pilot circuit via the controller, shorting the pilot circuit and stopping the boom, arm, and bucket regardless of the operating position of the operating valve. It's getting old.

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

In the figure, 1 is a frame such as a revolving body of a power shovel, 2 is a boom pivoted to this frame 1, 3 is an arm connected to the boom 2, 4 is a bucket connected to the arm 3, and 5 is a boom cylinder,
6 is an arm cylinder, and 7 is a bucket cylinder. Reference numerals 8 and 9 denote a group of valves that selectively supply hydraulic pressure from pumps 10 and 11 to each of the above-mentioned cylinders and a traveling device (not shown). In the valve groups 8 and 9, the first valve group 8 consists of a left traveling valve 8a, a boom valve 8b, a bucket valve 8c, and an arm valve 8d, and the second valve group 9 consists of a boom valve 9a,
It consists of an arm valve 9b, a bucket valve 9c, and a right travel valve 9d, and each valve is switched by the pilot pressure that selectively acts on the pilot pressure acting portions at both ends, and is returned to the neutral state by a spring. ing. 1
2 is a boom operation valve, 13 is an arm operation valve, and 14 is a bucket operation valve, and these are proportional control valves. Each of these operating valves and the pilot pressure acting portions provided at both ends of each corresponding valve are each connected to a pair of pilot circuits 12.
They are connected at a, 12b, 13a, 13b, 14a, and 14b. And between each set of pilot circuits are short-circuiting electromagnetic switching valves 16, 17, 18.
connected via.

A first potentiometer 19 is installed at the pivot point of the boom 2, a second potentiometer 20 is installed at the pivot point between the boom 2 and the arm 3, and a third potentiometer is installed at the pivot point between the arm 3 and the bucket 4. A meter 21 is attached to each. The signals of these potentiometers 19, 20, 21 are input to a controller (microcomputer) 22, and this controller 22 controls each of the electromagnetic switching valves 16, 1.
7 and 18 can be switched.

In the above configuration, each operation valve 12, 13, 14
By operating the valves, the valves of the valve groups 8 and 9 are selectively operated, and the boom 2, arm 3, and bucket 4 are operated by the expansion and contraction of the cylinders 5, 6, and 7.

At this time, the movements of the boom 2, arm 3, and bucket 4 are detected by each potentiometer 19, 20, and 21, and when the detected value reaches a certain value, a predetermined short-circuit electromagnetic signal is sent via the controller 22. The switching valves 16, 17, 18 are switched to shorten the pilot circuits. As a result, predetermined valves such as the arm valves 8b and 9a are returned to neutral, and the operation of the boom 2 is stopped even though the boom operation valve 12 is in the operating position.

The short-circuiting electromagnetic switching valves 16, 17, and 18 may be configured to short-circuit the pair of pilot circuits, or may be configured to drain both pilot circuits, respectively. Further, the potentiometers 19, 20, 21 may be limit switches. The electromagnetic switching valves 16, 17, and 18 are returned to their normal positions (off positions) by signals from the controller 22.

Effects of the invention According to the invention, when the boom 2, the arm 3, and the bucket 4 rotate by a predetermined angle during the expansion and contraction operations of the cylinders 6, 7, and 8 that actuate the boom 2, arm 3, and bucket 4, The short-circuiting solenoid switching valves 16, 17, 18 operate and each cylinder 6, 7,
Since the valve for 8 is returned to neutral regardless of the operation of the operation valves 12, 13, and 14, for example, by setting the electromagnetic switching valves 16, 17, and 18 to operate at the end of the stroke of the cylinder, each When the cylinder is stopped at the end of its stroke, pressure oil is not supplied to the cylinder even if the operating valve is moved further, so that there is no wasteful supply of pressure oil thereafter, and energy loss can be achieved. In addition, since the operation of the cylinder can be stopped mid-way without using the operating valve, if there is an interfering object at a certain position within the operating range, work can be done in front of the interfering object without having to operate the operating valve each time. The machine can be stopped.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. 2 is a boom, 3 is an arm, 4 is a bucket, 5 is a boom cylinder, 6 is an arm cylinder, 7 is a bucket cylinder, 12 is a boom operating valve, 13 is an arm operating valve, 14 is a bucket operating valve, 12a, 12
b, 13a, 13b, 14a, 14b are pilot circuits, 16, 17, 18 are electromagnetic switching valves, 19,
20 and 21 are potentiometers, and 22 is a controller.

Claims (1)

[Scope of utility model registration request] The boom cylinder 5, arm cylinder 6, and bucket cylinder 7 are connected to a hydraulic power source through valves that are switched by pilot pressure, and the pilot pressure for switching the respective valves is applied to the boom operating valve 12 and the arm operating valve. 13. In a power shovel operating device in which each cylinder expands and contracts through each valve by selectively controlling the bucket operating valve 14, each valve is connected to each operating valve 12, 13, 14. Inside the pilot circuit 12a, 12b, 13
a, 13b, 14a, 14b, electromagnetic switching valves 16, 17, 18 that short-circuit these pilot circuits.
boom 2, arm 3, bucket 4
An attitude detector such as a potentiometer 19, 20, 21 for detecting the rotation angle of each of these members is provided on each pivot part of the controller 2.
An operating device for a power shovel, characterized in that it is connected to the operating portions of the electromagnetic switching valves 16, 17, and 18 via 2.