JPH08158412A - Boom angle sensing device - Google Patents

Abstract

PURPOSE: To prevent breakage of a limit switch for sensing the boom angle and generation of error in sensing by mounting the switch in a position under a boom installed on the body. CONSTITUTION: A limit switch 33 for sensing the angle of a boom 20 senses the angle of a boom cylinder 26 based upon the fact that the cylinder angle corresponds unumbiguously to the angle of the boom 20. When the boom 20 moves in the upward direction to cause also lifting of the cylinder 26, its oversurface is lifted by a rod for opening/closing the contact of the switch 33, and the built-in contact of the switch 33 is changed over. Using bolt, a mounting plate of switch 33 is installed on the vertical plate part of a bracket fixed to a frame for installation of the cylinder 26 furnished on an upper revolving element 1c. Thereby the switch is protected againt dropping matter such as earth and sand or collision of any object owing to installation of the switch under the boom 20 to lead to prevention of breakage of the switch 33 and generation of error in sensing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a boom angle in a construction machine such as a hydraulic excavator or a crane in which a boom is mounted on a main body so that the boom can be raised and lowered.

[0002]

2. Description of the Related Art When excavating or loading a dump truck in a tunnel with a hydraulic excavator in which a bottom dump bucket or a backhoe bucket is attached to an articulated arm (composed of a boom and an arm), the height of the tunnel is increased. If it is low, part of the bucket or articulated arm may reach the ceiling of the tunnel and collapse the ceiling. In order to prevent such a collision of the boom or the like with the ceiling, a device for detecting the hoisting angle of the boom is provided, and when the angle is reached, an alarm is issued or the raising operation of the boom is stopped. The conventional boom angle detecting device is attached to the upper swing body so that the contact opening / closing rod of the limit switch contacts the upper surface of the root of the boom.

[0003]

However, according to the above-mentioned conventional structure, excavated earth and sand or other objects may fall on the limit switch, which may damage the limit switch or cause a corner to be detected. There was a problem.
The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a boom angle detection device that does not cause damage to a limit switch or the like and a detection roundabout due to collision of earth and sand or something.

[0004]

In order to achieve the above object, the present invention provides a construction in which a hydraulic cylinder for hoisting a boom attached to a main body is attached by connecting its base end portion to a lower portion of the boom on the main body. In the machine, a switch for detecting a boom angle is attached to a portion of the main body located below the boom.

[0005]

In the present invention, since the switch for detecting the boom angle is provided under the boom, the switch is prevented from colliding with a falling object such as earth and sand, and the switch is protected.

[0006]

1 is a left side view showing an embodiment of a construction machine according to the present invention in a working state in a tunnel for a hydraulic excavator, and FIG. 2 is a plan view. The body 1 of the hydraulic excavator
Is configured by installing the upper revolving structure 1c on the lower traveling structure 1a via the revolving device 1b. Reference numeral 2 denotes a hydraulic pump mounted on the upper revolving structure 1c of the hydraulic excavator. The hydraulic excavator of this example has a hydraulic pump 2 that can be used in sites where engine exhaust gas is disliked, such as in tunnel construction and underground construction. In order to drive the hydraulic pump 2 by the electric motor 4 alone so as to drive the hydraulic pump 2 in addition to the engine 3, the engine 3 is installed on the opposite side of the cab 1f in order to combine them compactly. The engine 3 and the electric motor 4 in front thereof and the hydraulic pump 2 in front of the electric motor 4 are installed coaxially on the rear side (right side) in the vertical direction, and the rotary shaft 7 of the engine 3 and the electric motor are installed. The rotary shaft 8 of the electric motor 4 is coupled with the rotary shaft 8 of the electric motor 4 via a double coupling 13 (a coupling in which elastic members for absorbing strain of the rotary shaft are provided at both ends of the spline) and a clutch 9. It becomes directly connected to an input shaft 11 of the hydraulic pump 2 via a ring 10.

Reference numeral 6a denotes a radiator for the engine 3, 6b denotes an oil cooler of a hydraulic system including the hydraulic pump 2,
Is a fan that is independent of these and also serves as a radiator 6a and an oil cooler 6b for sending cooling air to them, and 5a is a hydraulic motor for driving the fan. Reference numeral 14 denotes a counterweight mounted on the rear portion of the upper revolving structure 1c. The counterweight 14 and the upper revolving structure 1c are provided on the outer surface of the counterweight 14 so that a small turn can be made in a narrow site such as tunnel construction or underground construction. Is formed in an arc shape around the turning center of the turning device 1b and is configured not to project from the rear end of the lower traveling body 1a. Further, the fan 5 is housed in a wind tunnel 14 a provided so as to penetrate the counterweight 14. Reference numeral 15 is a cable reel around which a cable 16 for supplying electric power to the electric motor 4 is wound, and 17 is a tubular guide arm for separating cables, which is attached via a turning device 18.

As a method of supporting the cable 16, there are methods shown in FIGS. 3 (A) and 3 (B).
In this method, a power supply 80 is installed at or near the entrance of the tunnel 55, and a relay 82 that is connected to the power supply 80 via a cable 81 is provided above the tunnel 55, and a cable reel mounted on the hydraulic excavator A. This is a method of connecting the cable 16 wound around 15 to the relay 82. In the case of this system, a constant tension is applied to the cable 16 by a torque motor or the like, which is provided on the cable reel 15, and the cable 16 is pulled out as the excavation work by the hydraulic excavator A progresses. As described above, by performing work with the cable 16 floating in the air, the excavation of the hydraulic excavator A does not hinder excavation work and earth removal work in comparison with the method of crawling the cable on the ground. The cable 16 does not interfere with the dump truck and other construction machines. Further, since the cable 16 does not crawl on the ground, the influence of earth and sand and water is small, and the number of accidents due to electric leakage is reduced.

The system shown in FIG. 3B is a system in which a relay tool 82 is attached to the side wall of the tunnel 55 and the cable 16 is connected to the relay tool 82. In this case, the torque motor is not operated during excavation work. Even if the upper swing body 1c swings, a tension is set so that the arm 17 always faces the tunnel entrance side without applying a large hydraulic pressure for floating the cable 16 shown in FIG. The hydraulic pressure is raised so that the tension is such that the cable 16 can be wound up by the cable reel 15.

A boom angle detecting device according to the present invention will be described below. 20 is a boom rotatably attached to the upper swing body 1c by a pin 21, 22 is an arm rotatably attached to the boom 20 by a pin 23, and 24 is rotatably attached to the arm 23 by a pin 25. Bottom dump type bucket 26, the base end side of which is the upper swing body 1c
A boom cylinder connected to the upper side by a pin 28 and a tip connected to the side surface of the boom 20 by a pin 29 to attach one left and one right respectively, 30 is an arm cylinder provided between the boom 20 and the arm 23, and 31 is a boom It is a bucket cylinder provided between 20 and the bucket 24, and both are hydraulic cylinders. As can be seen from FIG. 2, the boom 20 is expanded from the middle portion toward the root side, so that the base end portion of the boom cylinder 26 is located below the boom 20.

Reference numeral 33 is a limit switch for detecting the angle of the boom 20, and since the angle of the boom cylinder 26 uniquely corresponds to the angle of the boom 20, the limit switch 33 changes the angle of the boom cylinder 26. It is something to detect. The side view of FIG. 4 and the plan view of FIG. 5 show the mounting structure of the limit switch 33. The limit switch 33 is such that the boom 30 moves in the raising direction.
When the boom cylinder 26 also rises and the upper surface of the boom cylinder 26 pushes up the contact opening / closing rod 33a of the limit switch 33, the internal contacts of the limit switch 33 are switched.

In FIGS. 4 and 5, 34 is the upper revolving structure 1.
Frame for mounting the boom cylinder 26 provided in c, 3
Reference numeral 5 denotes a bracket mounted on the frame 34 with bolts 36. A part of the mounting plate 38 of the limit switch 33 is fixed to the vertical plate portion of the bracket 35 with a bolt 39, and the other part is fixed with a bolt 40. The plurality of screw holes 35a are arranged in an annular shape around the mounting screw hole for the bolt 39, and the tilt angle of the limit switch 33 is adjusted by selecting the screw hole 33a into which the bolt 40 is screwed. Thus, the angle at which the boom cylinder 26 contacts the rod 33a is changed to change the detection angle.

FIG. 6A shows a hydraulic circuit for automatically stopping the raising operation of the boom 20 by operating the limit switch 33, 2 is the hydraulic pump, and 42 is the upper swing body 1c.
Control valve for boom cylinder 26 mounted on 4
3 is a pilot pump attached to the hydraulic pump 2, 4
4 is a pilot valve of the control valve 42, and 45 is an electromagnetic shutoff valve inserted in the boom raising side pilot circuit 46 of the pilot valve 44. By switching the pilot valve 44 to the right position, the control valve 42 is moved to the left. When the contact is closed due to the operation of the limit switch 33 during the raising operation of the boom 20 by switching to the position, the shutoff valve 4 from the battery 47 via the contact of the limit switch 33.
The solenoid 45a of No. 5 is excited to switch the shutoff valve 45 to the left position, and the left operation chamber 42a of the control valve 42 is
Pilot oil flows into the oil tank 50, the control valve 42 returns to the neutral position, and the raising operation of the boom 20 automatically stops.

FIG. 6B shows an electric circuit for issuing an alarm by the operation of the limit switch 33. The operation of the limit switch 33 causes the alarm buzzer 51 to ring and the alarm lamp 53 to light. . Boom raising automatic stop circuit of FIG. 6 (A) and FIG. 6 (B)
One or both alarm devices are provided. As shown in FIG. 1, when a dump truck (not shown) for excavating earth and sand in the tunnel 55 is used and the height of the tunnel 55 is low, the ceiling 55 of the bucket 24, the boom 20, or the like 55.
In order to avoid collision with a (indicated by a chain double-dashed line), the tilt angle of the limit switch 33 with respect to the bracket 35 is selected by selecting the screw hole 35a into which the bolt 40 is screwed. The limit switch 33 is set to operate when is small.

When the boom 20 is raised and the upper surface of the base end of the boom cylinder 26 abuts against the rod 33a of the limit switch 33 and pushes the rod 33a upward, as shown in FIG.
Since the contact of the limit switch 33 shown in (B) is closed, either automatic stop or alarm is issued.
If only an alarm is issued, the operator can use the pilot valve 4
Returning 4 to the neutral position prevents the bucket 24 or boom 20 from colliding with the tunnel ceiling.

As described above, since the limit switch 33 is attached to the lower portion of the boom 20, the limit switch 33 is protected from the collision of a falling object such as earth and sand, and the limit switch 33 is prevented from being damaged or the detection roundabout. It Further, if the detection angle of the boom 20 can be changed as in the present embodiment, the height at which the automatic stop or the alarm is generated is suitable according to the height of the ceiling or an obstacle above the outside. Can be changed to

INDUSTRIAL APPLICABILITY The present invention can be applied to a construction machine such as a hydraulic excavator having no electric motor, another excavator using a breaker or other excavator other than the hydraulic excavator, or a cargo handling machine such as a crane. It can also be applied to machines. In the present invention, as the switch for detecting the boom angle,
Other than the limit switch, other switches such as a proximity switch can be used.

[0018]

According to the first aspect of the present invention, the means for detecting the boom angle does not detect the angle of the boom itself, but detects the angle of the boom itself.
Since the angle of the boom cylinder corresponding to the boom angle is detected, and the switch as this angle detection means is installed below the boom, the switch is protected from falling objects such as dirt and sand, and collision of the switch. Detection circumvention is prevented.

According to the second aspect of the present invention, since the detection angle of the boom can be changed by adjusting the position of the switch,
Depending on the height of the ceiling in the tunnel construction or the upper obstacle in the outdoor construction, the height of the automatic stop or the alarm generation can be changed to a suitable height.

[Brief description of drawings]

FIG. 1 is a left side view showing a hydraulic excavator, which is an embodiment of a construction machine of the present invention, in a working state in a tunnel.

FIG. 2 is a plan view of the hydraulic excavator of the embodiment.

3 (A) and 3 (B) are side views showing a power supply system when work is performed in a tunnel by the hydraulic excavator of this embodiment.

FIG. 4 is a side view showing a limit switch mounting structure of the embodiment.

FIG. 5 is a plan view showing a limit switch mounting structure of the embodiment.

FIG. 6A is a hydraulic circuit diagram for automatically stopping the raising operation of the boom cylinder by actuating a limit switch in the embodiment, and FIG. 6B is an electric circuit diagram for issuing an alarm when the limit switch is actuated.

[Explanation of symbols]

1: Main body, 1a: Lower traveling body, 1b: Turning device, 1c:
Upper revolving structure, 20: boom, 26: boom cylinder, 3
3: Limit switch, 35: Bracket, 35a: Screw hole, 39, 40: Bolt

Claims (2)

[Claims] 1. In a construction machine in which a hydraulic cylinder for undulating a boom attached to a main body is attached by connecting a base end portion thereof to a lower portion of the boom on the main body, a boom angle detecting switch is provided on the main body. A boom angle detecting device, which is mounted at a position located below the boom. 2. The boom angle detecting device according to claim 1, wherein the switch is attached to the main body in a positionally adjustable manner, and the boom angle detected is changed by adjusting the position of the switch. .