JPH0257165B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a safety device for a hydraulic excavator such as a hydraulic power shovel. BACKGROUND OF THE INVENTION A commonly used working machine of a hydraulic excavator, such as a hydraulic power shovel or a shovel loader, usually has a three-bar link structure composed of three parts: a boom, an arm, and a bucket. By the way, due to the increase in urban civil engineering construction in recent years,
Work in narrow places such as narrow roads in residential areas is increasing, and driving on roads is also increasing. When a hydraulic excavator with a conventional three-bar linkage works on a narrow road, it blocks traffic. Also,
When working in narrow spaces such as narrow roads in residential areas,
In order to avoid affecting surrounding houses, the boom needs to be raised high in order to rotate the hydraulic excavator. If it is not possible to turn on the spot, it moves to a wider area and then turns to remove soil.
Therefore, work efficiency is significantly reduced. Furthermore, it was not possible to increase the speed of the transport vehicle when traveling on the road. The disadvantages of hydraulic excavators with these three-bar link working machines are that the working machines are quite large, making it difficult to make small turns;
This is due to the fact that even when the work equipment is stored, it cannot be made very small. In order to eliminate such drawbacks, Fig. 1a,
As shown in b, a hydraulic excavator Mp with a boom divided into two and a four-bar link work machine was realized. However, in the hydraulic excavation machine Mp having such a four-bar link work machine, when the work machine is extended from the storage position (see Figure 1 a) as shown by the dotted line Ln, or when the work machine is unloaded after excavation, When doing so, there is an inconvenience that the bucket hits the vehicle body at the position of arrow Ar (see Figure 1b). The present invention has been made to eliminate the above-mentioned disadvantages, and when the angle between the first boom and the second boom and the angle between the second boom and the arm reach a predetermined angle, the arm and the second This invention provides a safety device for a hydraulic excavator that returns a boom operating valve to a neutral position to prevent a working machine from hitting a vehicle body. Hereinafter, the present invention will be described in detail based on one embodiment of the accompanying drawings. In Figure 2, the first boom 1 is connected to the second boom 2.
is rotatably connected to the second boom 2, and the arm 3 is connected to the second boom 2.
are rotatably connected. Further, a bucket bag 4 is rotatably connected to the arm 3. Bars L ₁ , L ₃ and L ₂ , L ₄ of equal length
are connected so as to face each other and to be rotatable, thereby forming a parallel four-bar link Lp. bar material
The connecting part A between _L1 and _L2 is arranged on the outside of the first boom 1, which corresponds to the connecting part between the first boom 1 and the second boom 2, and the connecting part A between the bars _L2 and _L3 . B is the second
It is arranged on the outside of the second boom 2 corresponding to the connecting part between the boom 2 and the arm 3. Also, bars L ₃ and L ₄
A connecting portion C with the arm 3 is disposed on the outside of the arm 3. Therefore, the shape of the parallel four-bar link Lp changes as the arm 3 rotates. Limit switches 5 and 6 are parallel 4-bar links
It is arranged at a predetermined position on the outside of the first boom 1 so as to be turned on at the connecting portion D of Lp. Also, the line segment connecting the limit switch 5 and the connecting part A and the line segment connecting the limit switch 6 and the connecting part A form an angle of 30 degrees, and the limit switch 5
, the connecting part A, and the central axis of the first boom 1 (the connecting part A
passing through) and forming an angle of 5.32°. Further, the limit switch 7, which detects when the second boom 2 rotates toward the first boom 1 and the rotation angle of the second boom 2 reaches a predetermined angle, is placed at a predetermined position on the first boom 1; This limit switch 7
Dogs 8 for turning on the power are disposed at predetermined positions on the second boom 2, respectively. (Figure 3) In Figure 4, cylinders 10 and 11 are cylinders that operate the second boom 2 and arm 3, respectively, and hydraulic valves 13 and 14 are cylinders that operate the second boom 2 and arm 3, respectively.
Add operating oil to cylinders 10 and 11, and
This is a hydraulic valve that drives the expansion and contraction of 11. Bar material 13
a, 14a are connected to spools of hydraulic valves 13, 14, respectively, and operating levers 9a, 9b are provided at the other ends, respectively. operating lever 9a,
When 9b is operated to the lowering side (arrow Dn side), the cylinders 10 and 11 are both extended and rotate the second boom 2 and arm 3 counterclockwise, respectively.
Also, the operating levers 9a and 9b are on the upward side (arrow Up
side), the cylinders 10, 11 retract together and rotate the second boom 2 and arm 3 clockwise, respectively. In addition, a bar 1 is connected to the bars 13a and 14a through connecting portions 19a and 19c, respectively.
8 are rotatably connected, and the bar 18 and the connecting rod 12a of the hydraulic cylinder 12 are rotatably connected via the connecting portion 19b. The solenoid valve 15 is an oven center solenoid valve, and when turned on, applies hydraulic oil to the hydraulic cylinder 12 so that the connecting rod 12a retracts.
Position detectors 20 and 21 are hydraulic valves 13 and 1, respectively.
This is a hydraulic valve that detects that the rod 4 is in the neutral position, and is connected to the rods 13a and 14a through rods 20' and 21', respectively. Note that the pump Pm is a hydraulic pump. FIG. 5 is a block diagram showing a control system in an embodiment of the safety device for a hydraulic excavator according to the present invention. Based on the on/off states of the limit switches 5 to 7, the control circuit 23 drives the electromagnetic valve 15 using the electromagnetic driver 24, retracts the hydraulic cylinder 27, and moves the spools 26 and 27 of the hydraulic valves 13 and 14 to the neutral position. Now, Table 1 shows the relationship between the operations of the limit switches 5 to 7 and the operations of the solenoid valve 15 as the first boom 1, second boom 2, and arm 3 rotate.

[Table] However, the angle α represents the size of the angle between the center axis of the first boom (passing through the connecting part A) and the bar L ₂ (Fig. 2), and the angle β represents the angle between the bars L ₂ and L ₃ (Fig. 2), and Ls ₁ to Ls ₃ correspond to limit switches 5 to 7, respectively. FIG. 6 shows an embodiment in which the control circuit 23 is composed of a relay sequence circuit. A contact 5
a to 7a are limit switches 5 to 7, respectively.
The a-contacts 20a and 21a are a-contacts of the position detectors 20 and 21, respectively, and the lamp 30 is a lamp that indicates that the power is turned on. relay 31
35 are relays that are turned on and off by turning on and off the contacts 5a to 7a, 20a, and 21a. Contact 3
1a to 33a are the a contacts of the relays 31 to 33, and contacts 33b to 35b are the b contacts of the relays 33 to 35. The solenoid 36 is a solenoid for the electromagnetic valve 15, and the lamp 37 is a lamp that warns that the working machine will hit the vehicle body. Further, F is a fuse. Now, when the operating levers 20 and 21 are both in the neutral position and the working machine is α>23.96° and (α+β)>185.32° as shown in FIG.
0 and 21 detect the neutral position, and the contacts 20a and 21
Both a are turned on. As a result, relays 34, 3
5 is on, contacts 34b and 35b are off. Therefore, solenoid 36 is off and solenoid valve 15
is off, the hydraulic cylinder 12 is operated by the operating levers 9a,
It operates in conjunction with the operation of 9b. At this time, when the operating levers 9a and 9b are both operated downward, the hydraulic valves 13 and 14 are switched, the cylinders 10 and 11 are extended, and the second boom 2 and arm 3 are rotated counterclockwise. On the other hand, since the hydraulic valves 13 and 14 are switched from the neutral position, the contacts 20a and 21a are both turned off, and the relays 34 and 35 are turned off and the contacts 34b and 35 are turned off.
b turns on. Further, the contact 33b is turned on. When the bucket comes close to the vehicle body due to the action of the second boom 2 and arm 3, the connecting portion D of the parallel four-bar link Lp turns on the limit switch 5. As a result, the contact 5a is turned on, the relay 31 is turned on, and the contact 31a is turned on, so the solenoid 36 is turned on, the solenoid valve 15 is operated, and the lamp 37 is lit. Therefore, the hydraulic oil flows into the hydraulic cylinder 12, and the hydraulic cylinder 12 retracts. By this operation of the hydraulic cylinder 12, both the hydraulic valves 13 and 14 are switched to the neutral position, and the operating lever 9
a and 9b are moved to neutral positions. hydraulic valve 13,
14 is switched to the neutral position, position detector 2
0 and 21 operate, contacts 20a and 21a turn on, relays 34 and 35 turn on, and contacts 34b and 3
5b is turned off, the solenoid 36 is turned off, the solenoid valve 15 is returned to its original position, the retraction of the hydraulic cylinder 12 is stopped, and the lamp 37 is turned off. In addition, when the work equipment is stored, that is, α≦
When extending the work equipment from a state of 23.96° and (α+β) > 185.32°, rotate the first boom 1 clockwise and operate the control levers 9a, 9b to the lower side to lower the second boom 2 and Rotate arm 3 counterclockwise. In addition, the operation levers 9a, 9
b, the hydraulic valves 13 and 14 are switched from the neutral position to the position where the cylinders 10 and 11 are extended, so that the contacts 20a and 21 of the position detectors 20 and 21
a are both turned off, relays 34 and 35 are both turned off, and contacts 34b and 35b are both turned on. At this time, the limit switch 7 is first turned on, the relay 33 is turned on, the contact 33a is turned on,
Contact 33b is off. Next, as the second boom 2 and arm 3 rotate, the connecting portion D of the parallel four-bar link Lp turns on the limit switch 5, which turns on the contact 5a and turns on the relay 31.
Contact 31a is turned on. When the rotation of the second boom 2 and the arm 3 further increases, the connecting portion D turns on the limit switch 6. As a result, the contact 6a is turned on, the relay 32 is turned on, and the contact 32a is turned on. Therefore, the solenoid 36 is turned on, the solenoid valve 15 is operated, the hydraulic cylinder 12 is retracted, and the hydraulic valves 13,
14 is switched to the neutral position. Then, the position detectors 20 and 21 operate, and the contacts 20a and 21
a turns on, relays 34 and 35 turn on, and contact 3
4b and 35b are turned off, the solenoid 36 is turned off, the solenoid valve 15 is reset, and the lamp 37 is turned off. Note that once the hydraulic valve is switched to the neutral position as described above, the second boom and the arm can be raised using the operating lever. In this embodiment, the control circuit is formed of a relay sequence circuit, but the control circuit is not limited to this, and may be formed of a non-contact logic circuit or the like. In addition, in this embodiment, the angle between the first boom and the second boom, and the angle between the second boom and the arm are detected using a parallel four-bar ring and a limit switch, but they can also be detected directly using a potentiometer or the like. can be detected. Further, by replacing the parallel four-bar link of this embodiment with a non-parallel four-bar link and changing the placement position of the limit switch, the same angle detection can be performed. As explained above, according to the present invention, it is possible to prevent an accident in which a working machine hits a vehicle body.

[Brief explanation of the drawing]

FIG. 1 is a front view of a hydraulic excavator to which a hydraulic excavator safety device according to the present invention is applied, and FIGS. 2 and 3 are angle detection mechanisms in the hydraulic excavator safety device according to the present invention. FIG. 4 is a hydraulic circuit diagram showing an embodiment of the safety device for a hydraulic excavator according to the present invention, and FIG. 5 is a front view showing an embodiment of the hydraulic excavator according to the present invention. FIG. 6, a block diagram showing an embodiment of the safety device, is an electrical sequence circuit showing an embodiment of the control circuit in the safety device of a hydraulic excavator according to the present invention. 1...First boom, 2...Second boom, 3...
Arm, 4... Bucket, 5, 6, 7... Limit switch, 8... Dog, 9a, 9b... Operating lever, 12... Hydraulic cylinder, 12a... Connecting rod, 15... Solenoid valve, 18... Bar material, 19a~1
9c, D...Connection part, 20, 21...Position detector, 20', 21'...Bar material, 23...Control circuit,
24...Solenoid valve driver, 26...Second boom operation spool, 27...Arm operation spool, 3
0,37...Lamp, 31-35...Relay, 3
6...Solenoid, 5a to 7a, 20a, 21
a, 31a to 33a...a contact, 33b to 35b
...B contact.

Claims (1)

[Scope of Claims] 1. In a hydraulic excavation machine in which the work equipment includes a first boom, a second boom, an arm, and a bucket, the angle between the first boom and the second boom, and the second boom and the arm detecting the sum of the angle formed by the first boom and the second boom, and when the sum becomes smaller than a preset value determined corresponding to the angle formed by the first boom and the second boom, the second boom is A safety device for a hydraulic excavation machine, characterized in that a hydraulic valve of a hydraulic cylinder that operates and a hydraulic valve of a hydraulic cylinder that operates the arm are forcibly returned to a neutral position. 2. Detection of the sum of the angle formed by the first boom and the second boom and the angle formed by the second boom and the arm is performed at a joint between the first boom and the second boom, a parallel four-bar link having first to third connecting portions at a connecting portion between the two booms and the arm and at a predetermined position of the arm, and a fourth connecting portion is movable;
2. The safety device for a hydraulic excavator according to claim 1, wherein the safety device is implemented by a limit switch disposed at a predetermined position on the boom and turned on by contact with the fourth connecting portion of the four-bar link.