JP2002038535A - Control circuit for hydraulic shovel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic circuit for a back hoe shovel, which facilitates connection of circuits, and also facilitates switching operation of the circuits. SOLUTION: According to the back hoe shovel which can mount thereon a long attachment and a standard attachment in an exchangeable manner, a controllable pressure reducing valve is arranged across a pilot line. When the long attachment is mounted on the shovel, the speed of an actuator is regulated, while the regulation of the actuator speed is canceled to increase the speed when the standard attachment is mounted on the shovel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a hydraulic circuit of a hydraulic shovel that can be mounted by replacing a long attachment and a standard attachment.

[0002]

2. Description of the Related Art Conventionally, there is a hydraulic shovel in which a long attachment (or a very long attachment) is attached to a hydraulic shovel to enable work at a high place. If the boom, arm, or the like is moved at the same angular velocity as the standard (normal) attachment when using the long attachment, the speed of the tip becomes extremely large, and the work may be extremely difficult. Therefore, when the long attachment is mounted, it is necessary to reduce the moving speed of the arm cylinder or the boom cylinder to facilitate the work. On the other hand, when replacing the long attachment with a standard attachment,
If you operate at the same speed as the long attachment,
The operation speed is too slow, making it difficult to work. Therefore, conventionally, a hydraulic circuit that switches the speed of the actuator to control the operation speed suitable for both attachments has been used.

[0003] For example, Japanese Unexamined Patent Publication No. 7-31033.
The hydraulic circuit disclosed in No. 7 switches between a very long attachment (or a long attachment) and a normally used attachment to make it usable. FIG. 4 shows a side view of the ultra-long attachment, and FIG. 5 shows a conventional attachment with a bucket for digging. FIG. 6 shows a hydraulic circuit diagram. As shown in FIG. 4, in the working machine 8, an upper revolving unit 10 is provided on a lower traveling unit 9 so as to be freely rotatable, and an attachment 11 is mounted on the upper revolving unit 10. The attachment 11 is a very long attachment, and includes a first boom 12, a second boom 18, and a third boom 1.
9, an arm 20, a crusher (work tool device) 21, and boom cylinders 22 to 24 for driving and controlling them, and an arm cylinder 25. As shown in FIG. 5, the attachment 28 for normal use includes the boom 13 and the arm 3.
1, a bucket 32 and hydraulic cylinders 22, 25, and 26 for driving and controlling them.

When the ultra-long attachment 11 is mounted, a hydraulic circuit is formed by the hydraulic cylinders 22 to 25 so that the hydraulic cylinder can be bent slowly and longitudinally at low speed. On the other hand, when the attachment 28 is mounted, it is necessary to switch the hydraulic circuit so that it can bend and rotate at a normal high speed. In the hydraulic circuit shown in FIG. 6, the switching valves for controlling the actuators are divided into two groups A and B, and pressure oil from the first pump 42 and the second pump 43 is supplied to each group. Switching valve 33L, 3
3R is provided in the front row of each group, and this and the other actuator switching valve are connected in tandem, and the other actuator switching valves are respectively connected in parallel. Further, it is connected so that the pressure oil is supplied from any one of the two groups A and B to the other actuator switching valve other than the above group.

[0005] When the normal attachment 28 is mounted from the ultra-long attachment 11, the boom cylinders 23 and 24 are removed from the plurality of boom cylinders 22 to 24. In this case, as shown in FIG. 6, the arm cylinder 25 in one group A and the first boom cylinder 22 in the other group B are merged. For this,
The rod-side oil chamber 68, which is the merging-side oil chamber of the arm cylinder 25 in the group A, and the pressure oil supply circuit 69 in the group B
Are communicated via a pilot opening / closing valve 47 for arm merging, and a pilot port 70 of the pilot opening / closing valve 47 for arm merging and a pilot port 71 on the merging operation side of the pilot switching valve 35 for arm are communicated via a pilot line. ing.

Further, a bottom side oil chamber 72 on the merging chamber side of the first boom cylinder 22 in the group B and a pressure oil supply circuit 73 of the group A are communicated via a boom merging pilot opening / closing valve 46. The pilot port 74 of the boom merging pilot on-off valve 46 and the merging operation-side pilot port of the first boom pilot switching valve 36 communicate with each other via a pilot line, and selector valves 51 and 52 are connected to the two pilot lines, respectively. The configuration is interposed.

In the above-mentioned hydraulic circuit, not only the connection of the pilot line becomes complicated, but also the selector valve is provided, so that it is necessary to switch the selector valve every time the attachment is switched, and the switching operation is complicated. There was a problem that. In addition, the selector valve is 2
There is also a possibility that one of them may be forgotten to switch, and in this case, there is a problem that an accident may occur.

[0008]

SUMMARY OF THE INVENTION The present invention has been made under the above-mentioned background, and the connection of circuits is easy.
An object of the present invention is to provide a hydraulic circuit of a hydraulic shovel in which a switching operation can be performed by a simple operation.

[0009]

The present invention employs the following means to solve the above-mentioned problems. That is, claim 1
The described invention is directed to a hydraulic excavator that can be mounted by exchanging a long attachment and a standard attachment, in which a controllable pressure reducing valve is provided in a pilot line to regulate the speed of the actuator when the long attachment is mounted, and to control the speed when the standard attachment is mounted. It is characterized by removing restrictions and increasing speed.

According to a second aspect of the present invention, in the first aspect of the invention, the pressure reducing valve is connected to an oil passage between a boom lowering output port of a boom remote control valve and a pilot port of a boom switching valve, and an arm remote control valve. And a connecting oil path between the arm closing side output port and the pilot port of the arm switching valve and a connecting oil path between the bucket closing side output port of the bucket remote control valve and the pilot port of the bucket switching valve, respectively. I have.

According to a third aspect of the present invention, in the first aspect of the present invention, the pressure reducing valve is one of
It is characterized in that the operation speed at the time of attachment replacement can be switched by one signal or one operation.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the pressure reducing valve includes a plurality of switching valves or pressure reducing valves connected in parallel to form a pressure reducing valve unit. The unit is connected so that the pressure reducing function does not occur when the pilot pressure is applied to the control port of the unit, but the pressure reducing function occurs when the control port is set to the oil tank pressure.

[0013]

FIG. 1 shows a main configuration of a hydraulic circuit according to an embodiment. Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, the switching valves of each actuator are classified into two groups A and B, and the hydraulic pump 1
4 and 15 are connected to the output side center oil passages. The connection of the switching valve for controlling each actuator may be connected in the same manner as in the prior art. That is, a traveling motor switching valve (not shown) is provided in the front row of each group, this and the other actuator switching valve are connected in tandem, and the other actuator switching valves are respectively connected in parallel.

In FIG. 1, the second boom switching valve 44, the swing motor switching valve 45, and the first arm switching valve 46 are classified into group A and connected to the hydraulic pump 14, and the first boom switching valve 47 is provided. , The bucket switching valve 48 and the second arm switching valve 49 are classified into group B and connected to the hydraulic pump 15. The output port of the first boom switching valve 47 is connected to the bottom port 53a and the rod port 53b of the boom cylinder 53, respectively, and the output port of the second boom switching valve 44 is connected to the bottom port 53a of the boom cylinder 53.
It is connected so that it joins to reinforce the raising operation of the boom. The output ports of the first arm switching valve 46 and the second arm switching valve 49 are merged and connected to the bottom port 55a and the rod side port 55b of the arm cylinder 55. The output port of the bucket switching valve 48 is connected to the bottom port 56 a and the rod port 56 b of the bucket cylinder 56.

The pilot port 4 for supplying and controlling hydraulic oil from the hydraulic pump 15 to the lower pilot port 47b of the first boom switching valve 47, that is, the rod port 53b.
Reference numeral 7b is connected to the output port of the boom remote control valve 57 via the pressure reducing valve 4c of the pressure reducing valve unit 4 and the oil passage 3. The pilot port on the opposite side of the first boom switching valve 47 and the pilot port (not shown) of the second boom switching valve 44 are directly connected to the output port of the boom remote control valve 57 via an oil passage (not shown). Connected).

Similarly, the pilot port 46b for supplying and controlling hydraulic oil from the hydraulic pump 14 to the closing side pilot port of the first arm switching valve 46, that is, the rod side port 55b when a pilot pressure is applied, is a pressure reducing valve. Remote control valve 5 for arm through pressure reducing valve 4a of unit 4 and oil passage 1
9 output ports. The pilot port on the opposite side of the first boom switching valve and the pilot port (not shown) of the second boom switching valve are directly connected to the output port of the boom remote control valve 59 by an oil passage (not shown).

The pilot port 48a for supplying and controlling hydraulic oil from the hydraulic pump 15 to the closed side pilot port 48a of the bucket switching valve 48, that is, the bottom side port 56a when a pilot pressure is applied, is connected to the pressure reducing valve unit 4. The pressure reducing valve 4 b is connected to the output port of the bucket remote control valve 58 via the oil passage 2. Remote control valve 1
The input port 3 is connected to the pilot hydraulic pump 60 and an oil tank (not shown).

FIG. 2 shows an example in which the pressure reducing valve unit 4 is constituted by a direction switching valve. In FIG. 2, three switching valves 4a-4
(c) is connected to the high pressure side ports 61a to 63a of the pressure reducing valve unit 4,
The port (right port) is connected to the control port 64 by the oil passage 65.
And the right pilot ports of the switching valves 4a to 4c are connected to the control port 64, respectively. Three switching valves 4a
4c are connected to the low-pressure ports 61b to 63b of the pressure reducing valve unit 4, and at the same time, the three switching valves 4a to 4c are connected.
The output port of 4c is connected to each opposite (left) pilot port for feedback. The switching valve 4
An adjustable spring force is simultaneously applied to the right pilot ports a to 4c. The control port 64
, A pilot hydraulic pressure equal to or higher than the pilot hydraulic pressure acting on the input ports 61a to 63a of the pressure reducing valve unit 4 is applied.

Since the switching valves 4a to 4c operate with the same function, only the function of the switching valve 4a will be described. When the pilot oil pressure is applied to the control port 64 of the pressure reducing valve unit 4, regardless of the pressure applied to the input port 61a,
The switching valve 4a always maintains the state B by the spring force. When the control port 64 is set to the oil tank pressure, the input port 6
When the hydraulic pressure acting on 1a is low, the state is low due to the spring force, but as the acting hydraulic pressure increases, the hydraulic pressure of the output port 61b acts on the left pilot port, and the output pressure is reduced. In the present embodiment, the input ports 61a to 63a and the control port 64 of the pressure reducing unit act on the same pilot pressure oil.

FIG. 3 illustrates an example in which a pressure reducing unit is configured using a pressure reducing valve. The pressure reducing unit is configured using three pressure reducing valves shown in FIG. In the figure, the high pressure side port 66 is connected to an input side port, for example, a port 61a, and the low pressure side port 67 is connected to an output side port, for example, a port 61b. The drain port 74 is connected in parallel to the control port 64. By connecting as described above, a decompression unit having the same function as the above-described decompression unit 4 can be obtained.

In FIG. 3, when a pilot pressure P1 of a predetermined value or more is applied to the control port 64, the control port 6
The poppet valve opens against the spring force by the hydraulic pressure of 4, the pilot pressure P1 acts on the F chamber, and the spool S is always in close contact with the lower surface. In this state, the input side port 61a
The pilot pressure P acting on the output port 61
b. On the other hand, when the oil tank pressure is applied to the control port 64, the pilot pressure P applied to the input port 61a is reduced in pressure because a part of the pilot pressure P is negatively fed back by the oil passage E, and is applied to the output port 61b. appear. Therefore, FIG.
It functions similarly to the decompression unit.

As described above, the pressure reducing unit 4 can switch between the pressure reducing operation and the non-pressure reducing operation by switching the operation pressure of the control port 64. This switching is shown in FIG.
It is also possible to switch using a switch SW using an electromagnetic switching valve 65 as shown in FIG. The two input ports of the electromagnetic switching valve 65 are connected to a pilot hydraulic pump and an oil tank, and one of the output ports is connected to the control port 6.
4 and the other output port is closed. Note that a manual switching valve may be used instead of the electromagnetic switching valve, or other similar means may be used.

With the configuration described above, this embodiment functions as follows. That is, by switching the switching means such as an electromagnetic switching valve to apply the pilot pressure to the control port, the input pressure of the pressure reducing unit appears as the output pressure as it is, so that it is used as a normal hydraulic circuit when a hydraulic shovel is used. Operate. When the control port is set at the pressure of the hydraulic tank, the input pressure of the pressure reducing unit outputs a reduced output pressure. Therefore, since the pilot oil passage of the switching valve interposing the pressure reducing unit is reduced in pressure as compared with the normal case, the actuator operates at a slower speed. For this reason, the speed of the tip at the time of using the long attachment becomes slow, and fine operation becomes easy.

When the long attachment is used, the pilot pressure acting on the predetermined pilot port of the directional control valve for controlling the actuator is reduced, so that the spool of the directional control valve does not move a full stroke, and the normal attachment is used. Operation force is smaller than the operation force. It is common practice to reduce the relief pressure of the overload relief valve in consideration of the strength of the structure when using a long attachment. However, by adjusting the pressure reduction ratio of the pressure reducing unit, that is, the spring force acting on the spool, it is not necessary to adjust the relief pressure of the overload relief valve. There is no need to reduce the relief pressure.

The embodiments and examples of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the examples, and changes in design and the like may be made without departing from the gist of the present invention. Even if there is, it is included in the present invention.

[0026]

As described above, according to the structure of the present invention, a hydraulic circuit in which a long attachment and a normally used attachment can be exchanged can be constituted with a simple circuit constitution, and the switching work at the time of exchange can be performed. The effect of simplification is obtained.

[Brief description of the drawings]

FIG. 1 shows a configuration of a hydraulic circuit according to an embodiment of the present invention.

FIG. 2 shows a configuration example of a pressure reducing valve unit.

FIG. 3 shows another configuration example of the pressure reducing valve unit.

FIG. 4 shows a long attachment of the conventional device.

FIG. 5 shows a standard specification attachment of a conventional device.

FIG. 6 shows a hydraulic circuit of a conventional device.

[Explanation of symbols]

 4 pressure reducing valve unit 4a, 4b, 4c switching valve 44 second boom switching valve 46 first arm switching valve 47 first boom switching valve 48 bucket switching valve 49 second arm switching valve 53 boom cylinder 55 arm cylinder 56 bucket cylinder 61a, 62a, 63a High pressure side port 61b, 62b, 63b Low pressure side port 64 Control port

Claims (4)

[Claims] 1. A hydraulic excavator that can be mounted by replacing a long attachment with a standard attachment. A controllable pressure reducing valve is provided in a pilot line to regulate the speed of the actuator when the long attachment is mounted, and to control the speed of the actuator when the standard attachment is mounted. A control circuit for a hydraulic excavator, wherein regulation is lifted to increase speed. 2. An oil passage for connecting a pressure reducing valve between a boom lowering output port of a boom remote control valve and a pilot port of a boom switching valve, an arm closing side output port of an arm remote control valve, and a pilot port of an arm switching valve. 2. The control circuit for a hydraulic shovel according to claim 1, wherein the control oil circuit is provided in a connection oil passage between a bucket closing side output port of the bucket remote control valve and a pilot port of the bucket switching valve. 3. The pressure reducing valve according to claim 1, wherein the operation speed at the time of switching the attachment can be switched by one signal or one operation.
A control circuit for a hydraulic shovel according to item 1. 4. The pressure reducing valve forms a pressure reducing valve unit by connecting a plurality of switching valves or pressure reducing valves in parallel, and when a pilot pressure is applied to a control port of the unit, the pressure reducing function does not occur. 4. The control circuit for a hydraulic shovel according to claim 1, wherein the control port is connected so as to generate a pressure reducing function when the control port is set to an oil tank pressure.