JPH02213525A - Oil hydraulic circuit of side gutter trench - Google Patents

Abstract

PURPOSE:To improve the working efficiency and the safety without narrowing or reducing work range by setting each directional control valve in neutral position with a control valve when the positions of at least a boom, an arm and an offset link are all in dangerous areas. CONSTITUTION:When rotating positions in dangerous direction of a boom lower, an offset link and an arm enter dangerous areas, directional control valves 5a-8a are changed over through a cam 5c or an operating rod 5b, and pressure oil in a pilot pump 17 is supplied to control valves 10c-13c through the direction control valve 5a, etc. The constitution is so arranged that the pilot port on a side to drive the boom lower, etc., of directional control valves 10a-13a in dangerous direction is communicated with a tank 18 by changing over the position of the control valve 10c., etc., and the directional control valves 10a-13a are immediately returned to neutral positions. This arrangement enables the boom lower, etc., to stop so as to avoid the collision of the tip of a bucket and an operator cab.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hydraulic circuit for a ditch digging front that drives the @ ditch digging front attached to a hydraulic excavator when excavating ditches on a road or the like.

[Conventional technology]

Hydraulic excavators are commonly used for various excavation operations. One of these types of excavation work is side: A excavation work that forms side ditches along roads. This side ditch digging work is difficult to carry out by using a normal front consisting of a boom, arm, and bucket. will be implemented. The outline of the structure of this ditch digging front will be explained with reference to the drawings.

FIGS. 3(a) and 3(b) are a side view and a plan view of a part of a hydraulic excavator to which a trench digging front is attached. In each figure, 1 is the lower traveling body, 2 is the main body rotatably provided on the lower traveling body 1, 3 is the operator's cab provided on the main body 2, and 4 is the ditch digging front attached to the main body 2. be. The ditch digging front 4 includes a boom lower 5 rotatably attached to the main body 2, an offset link 6 rotatably attached to the boom lower 5, a boom upper 7 rotatably attached to the offset link 6, It is composed of an arm 8 rotatably attached to the boom upper 7 and a bucket 9 rotatably attached to the arm 8.

10 is a first boom cylinder that drives the boom lower 5, 11 is an offset cylinder that drives the offset link 6, and 12 is a second boom cylinder that drives the boom upper 7 (not shown in FIG. 3(a)). ing)
, 13 is an arm cylinder that drives the arm 8, and 14 is a bucket cylinder that drives the bucket 9.

When excavating a side ditch, the offset cylinder 11 is driven and the offset link 6 is rotated laterally as shown in FIG. 3(b). This allows the boom upper 7
, the arm 8 and the bucket 9 are aligned with the center line C of the hydraulic excavator.
In this state, the ditch can be excavated.

[Problem to be solved by the invention]

When the side trench excavator front 4 is in the position shown in FIG. There was a risk that the claw part) could collide with the front of the driver's cab 3 and destroy it. In order to avoid this danger, the operator must be constantly alert during the work, which poses a problem of increasing the burden on the operator. On the other hand, in order to solve this problem, measures have been taken to limit the stroke length of the arm cylinder 13 or to use a short arm 8, but these measures do not make it easy to carry out side ditch digging work. In this case, the operating range of the arm 8 is narrowed, which in turn narrows the working range, resulting in a problem that working efficiency is reduced. Of course, the same problem occurs when normal work is carried out in the middle of ditch digging work.

The purpose of the present invention is to solve the problems in the above-mentioned prior art,
It can prevent collision between the tip of the bucket and the driver's cab.
Moreover, it is an object of the present invention to provide a hydraulic circuit for a trench excavator front which can also prevent a reduction in the working range.

[Means to solve the problem]

To achieve the above object, the present invention provides a boom.

Each hydraulic actuator drives the arm, the offset link, and the bucket, each directional switching valve controls the drive of each of these hydraulic actuators, and each hydraulic actuator is driven according to the operation of each operating means that operates each hydraulic actuator. In a hydraulic circuit of a ditch excavation front comprising a pilot valve and each pilot pipe connecting each of these pilot valves and each of the directional control valves, the position of at least the selected working member of the boom, the arm, and the offset link. a dangerous area detecting means that operates when all of the selected working members are in a predetermined dangerous area; The present invention is characterized in that each control valve is provided to set each direction switching valve of the working member to a neutral position.

[For production]

When at least the positions of the boom, arm and offset link all enter their respective predetermined danger areas, the danger area detection means is actuated, which actuates the control valve to move the boom, arm and offset links into their respective predetermined danger areas. Return each directional control valve to its neutral position and stop them to prevent a collision between the tip of the bucket and the operator's cab.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a circuit diagram of a hydraulic circuit for a trench excavator front according to a first embodiment of the present invention. In the figure, 10a is a directional control valve that controls the drive of the first boom cylinder 10, and 10b is a pilot that supplies pilot pressure to the directional control valve 10a according to the amount and direction of operation of the boom lever that operates the boom lower 5. The valve 10c is a control valve interposed in one of the pilot pipes connecting the directional control valve 10a and the pilot valve 10b. Similarly, lla is the directional switching valve of the offset cylinder 11, and llb is the directional switching valve 11a.
The pilot valve llc is a control valve interposed in one of the pilot pipes. Further, 13a is a direction switching valve of the arm cylinder 13, and 13b is a direction switching valve 13a.
The pilot valve 13c is a control valve interposed in one of the pilot pipes. Each control valve 10C, l
ie.

The pilot lines 13c are connected in parallel.

5a, 6a, 8a are switching valves, 5b, 6b, sb, respectively.
are operating rods of the switching valves 5a, 6a, and 8a, respectively. The switching valves 5a, 6a, 8a are connected in series, and this series hydraulic circuit is connected to the parallel hydraulic circuit of each control valve 10c, llc, 13c. A cam that rotates, 6C is a cam that rotates in conjunction with the rotation of the offset link 6, and 8c is a cam that rotates in conjunction with the rotation of the arm 8. Each cam 5c.

5c and gc are in contact with operating rods 5b, 6b, and 8b, respectively. The rotation angle θ of cam 5C is the boom lower
The safe area of 50 rotations is shown. In addition, boom lower-50
The rotation range is indicated by θ,'. Similarly cams 6c, 8
Rotation angle θ6 of c. θ.

indicate the safe rotation areas of the offset link 6 and arm 8, respectively. Note that illustration of their rotation ranges is omitted.

Further, the arrows attached to the respective cams 5c, 6c, and 8c indicate the rotation directions of the respective cams 5c, 5c, and 13c when the boom lower 5, offset link 6, and arm 8 rotate in the dangerous direction. The dangerous direction of the boom lower 5 is the direction of raising the boom lower, the dangerous direction of the offset link 6 is the direction of turning to the offset position, and the dangerous direction of the arm 8 is the arm retracting direction. 17 is a pilot pump that supplies pilot pressure oil, and 18 is a tank.

Next, the operation of this embodiment will be explained. boom lower-5,
Offset link 6 and arm 8 are in safety area θ3. θ
,, θ8, the switching valves 5a, 6a, 8a are not operated. Therefore, the control valves 10c, llc, 13
Pilot pressure is not supplied to the pilot boat in c.
Pilot valve tab, iib, tab and directional valve 10
The pilot pipe line with a, 11a, and 13a is a control valve 10c.
.

11c and 13c, which allows normal operation.

In this state, boom lower 5, offset link 6,
one or two of the arms 8, e.g. boom lower
5 and the offset link 6 in the dangerous direction, the convex portions of the cams 5c, 6c come into contact with the operating rods 5b, 6b and press them. Therefore, the switching valve 5a t6a is switched from the illustrated position to the right side position. However, in this case, since the arm 8 has not been rotated to the dangerous area, the tip of the bucket 9 is in the operator's cab regardless of the rotational position of the boom lower 5 or the offset link 6. There is no risk of collision with the switching valve 8a.
is still in the position shown.

Therefore, the control valves 10c, llc, and 13c are not operated, and the boom lower 5, offset link 6, and arm 8 are driven normally.

Next, when the rotational positions of the boom lower 5, offset link 6, and arm 8 in the dangerous direction are all in the dangerous area, all of the switching valves 5a, 6a, and 8a are switched from the illustrated positions to the right positions.

Then, the pressure oil of the pilot pump 17 is transferred to each switching valve 5.
control valves 10c, 11c, 13c via a, 6a, 8a
These control valves 10c,
llc, 13c are switched from the illustrated position to the right position. As a result, in each of the directional control valves 10a, lla, and 13a, the pilot boat on the side that drives the boom lower 5, offset link 6, and arm 8 in the dangerous direction communicates with the tank 18, and each of the directional control valves 10a, tla, and 13a communicate with the tank 18. 13a
immediately returns to neutral position. Therefore, the boom lower
5. The offset link 6 and the arm 8 are in a stopped state at that point, and a situation where the tip of the bucket 9 collides with the driver's cab 3 can be avoided.

From this stopped state, the directional control valves 10a, iia.

13a in the safe direction, the corresponding switching valve returns to the illustrated position, and each control valve 10c, ll
c, 13c can also return to the illustrated position and return to the normal state.

In this way, in this embodiment, each control valve is operated by switching each switching valve only when all rotational positions of the boom lower offset link and arm are in the danger area.
Since each directional control valve is returned to the neutral position, even if there is no limit to the stroke length of the arm cylinder or a normal arm with a long length is used, the connection between the operator's cab and the tip of the bucket is ensured. Collisions can be avoided. and,
There is no stroke length limit and work can be done using a long standard length arm.
Work efficiency will not decrease due to a reduction in the work scope.

FIG. 2 is a circuit diagram of a hydraulic circuit for a trench excavator front according to a second embodiment of the present invention. In the figure, parts that are the same as or equivalent to those shown in FIG. 1 are given the same reference numerals and their explanations will be omitted. Reference numeral 19 is a throttle for securing pilot pressure to other pilot pipes.

The control valves 10c, llc, and 13c of this embodiment are always in a state where pilot pressure is introduced, and the switching valves 5a, 6a, and 8a of this embodiment are controlled by the rotation of the boom lower 5, offset link 6, and arm 8. It is in the cut-off state when the position is in the safe area.

The operation of this embodiment is similar to that of the previous embodiment.

That is, when at least one of the rotational positions of the boom lower 5, the offset link 6, and the arm 8 is in the safe R range, each of the control valves 10c, llc, and 13C is disconnected from communication between the pilot boat and the tank 18 as shown in the figure. maintained in position. When all of the rotational positions of the boom lower 5, offset link 6, and arm 8 enter the danger area, each control valve 10c, llc, 13c communicates with the pilot boat and tank 18, and the control valve 10c, llc, 13c is placed in the illustrated position. to the left position. As a result, each direction switching valve 1
0a, lla, 13a, the pilot boat communicates with the tank 18, is returned to the neutral position, and the boom lower
5. The offset link 6 and arm 8 are in a stopped state. The effects of this embodiment are the same as those of the previous embodiment.

In addition, in the explanation of the above embodiment, an example was described in which the rotational position of the boom lower offset link and the arm is detected by a cam, but the invention is not limited to this. You can also do it.

In addition, although we have explained an example in which switching valves are provided corresponding to each of the boom lower offset link and the arm, it is also possible to provide a means for generating a signal corresponding to the rotational position of the boom lower offset link and the arm, and to AND the signals. The output of the AND circuit can also be used as a drive signal for one switching valve connected to the parallel circuit of each control valve. Furthermore, a bucket can be added as a control object in addition to the boom lower, offset link, and arm.

〔Effect of the invention〕

As described above, in the present invention, when at least the positions of the boom, arm, and offset link are all in the danger area, the control valve is operated to set each directional control valve to the neutral position. Collision between the operator's cab and the tip of the bucket can be avoided even if a normal arm with no stroke length limit or a long length is used.

Moreover, since the above-mentioned arm can be used, the work range is not completely destroyed, and work efficiency can be improved.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams of the hydraulic circuit of the side ditch digging front according to the first and second embodiments of the present invention, and FIGS. 3(a) and 3(b) are the hydraulic circuits of the side ditch digging front FIG. 3 is a side view and a plan view of a portion of the excavator. 3... Driver's cab, 4... Gutter digging front, 5... Boom lower 2
5a, 5a, 13a......Switching valve, 5b,
6b, 8b......Operating rod, 5C, 6C
, 8c......cam, 6......
Offset link, 7...Boom upper, 8...Arm, 9...
bucket, toa, lla, 13a...
Directional switching valve, 10b, Ilb, 13b...
・Pilot valve, 10c, llc, 13c...
...Side door valve. Figure 3 (Q)

Claims (2)

[Claims] (1) Each hydraulic actuator that drives the boom, arm, offset link, and bucket, and each directional control valve that controls the drive of each of these hydraulic actuators, and each hydraulic actuator that operates according to the operation of each operating means that operates each hydraulic actuator. In a hydraulic circuit for a side trench excavation front, which includes pilot valves driven by the directional control valves and pilot pipes connecting the pilot valves and the directional control valves, at least selected ones of the boom, the arm, and the offset link are provided. a dangerous area detection means that operates when all of the working members are located in a predetermined dangerous area;
Each control valve is provided in the pilot pipe of the directional switching valve of the selected working member and sets each directional switching valve of the selected working member to a neutral position when the dangerous area detection means is activated. A hydraulic circuit for the front side of a trench excavator. (2) In claim (1), the dangerous area detection means includes at least each cam interlocked with the operation of the boom, arm, and offset link, and each switch connected to each of these cams and connected in series with each other. 1. A hydraulic circuit for a trench excavation front, comprising a valve and a pipe line connecting a series circuit of each of these switching valves to a parallel circuit of each of the control valves.