JP3221268B2 - Hydraulic circuit of excavator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic excavator in which a crusher or a breaker is exchangeably mounted on a front link mechanism, when a crusher is mounted and when a breaker is mounted. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit of a hydraulic shovel capable of forming a flow of a working oil.

[0002]

2. Description of the Related Art A hydraulic excavator has an upper revolving structure which is rotatably mounted on a lower traveling structure having a crawler belt. The upper revolving structure is provided with a driver's cab and a front working mechanism. The front working mechanism has a boom connected to the upper revolving unit so as to be able to elevate, an arm is connected to the end of the boom so that it can rotate vertically, and a front link mechanism is provided at the end of the arm. A front attachment is detachably connected to the front link mechanism.
A typical example of the front attachment is a bucket for performing operations such as excavation of earth and sand. In addition to this bucket, for example, a crusher, a breaker, or the like is attached.

[0003] A hydraulic actuator is mounted to drive the excavator to run, turn and operate the front working mechanism. That is, traveling and turning are driven by a hydraulic motor, and the operation of the front working mechanism is driven by a hydraulic cylinder. A hydraulic circuit for driving a hydraulic actuator including the hydraulic motor and the hydraulic cylinder is shown in FIG. The configuration shown in FIG. 1 is conventionally used.

This hydraulic circuit includes first and second hydraulic pumps 1 and 2, and the first and second hydraulic pumps 1 and 2 each include a first and a second hydraulic pump 1 and 2 comprising a plurality of directional control valves.
Second direction switching valve groups 3 and 4 are connected. A hydraulic actuator is connected to each of the directional control valves constituting the first and second directional control valve groups 3 and 4, respectively.
By performing the switching operation of the direction switching valve, the hydraulic oil is supplied to the hydraulic actuators, and the hydraulic actuators are driven. Each directional control valve is provided with a pair of pilot units, and when a pilot signal is supplied to any of these pilot units,
Pressure oil from the hydraulic pumps 1 and 2 is supplied to a hydraulic actuator. In order to supply a pilot signal to each direction switching valve, a pilot operation valve is provided in the cab.

[0005] The hydraulic actuators constituting the hydraulic excavator include left and right traveling hydraulic motors 5a and 5b, a turning hydraulic motor 6, a boom hydraulic cylinder 7, an arm hydraulic cylinder 8, and a bucket hydraulic cylinder 9. ing. Here, since the boom hydraulic cylinder 7 and the arm hydraulic cylinder 8 require a large flow rate, the hydraulic oil from both hydraulic pumps 1 and 2 is combined.

In the illustrated hydraulic circuit, the first directional control valve group 3 connected to the first hydraulic pump 1 has 5
Directional control valves 3a to 3e are connected.
Second directional control valve group 4 connected to the hydraulic pump 2
Is connected to four directional control valves 4a to 4d. First
The direction switching valve 3a constituting the direction switching valve group 3 is provided for the traveling hydraulic motor 5a, the direction switching valve 3c is provided for the boom hydraulic cylinder 7, the direction switching valve 3d is provided for the arm hydraulic cylinder 8,
Further, the direction switching valve 3e is connected to the turning hydraulic motor 6. The direction switching valve 4a constituting the second direction switching valve group 4 is connected to the traveling hydraulic motor 5b, the direction switching valve 4b is connected to the bucket hydraulic cylinder 9, the direction switching valve 4c is connected to the boom hydraulic cylinder 7, and furthermore. The direction switching valve 4d is connected to the arm hydraulic cylinder 8. Here, the bucket hydraulic cylinder 9 is for operating the front link mechanism.

This front link mechanism includes a crusher 10
And the breaker 11 are detachably connected. And these crusher 10 and breaker 11
It is itself hydraulically driven.

As shown, the crusher 10 has a pair of crushing claws 10a, 10a.
Is rotatably attached to the support shaft 10b, and a hydraulic cylinder 10c for a crusher is connected to a portion closer to the base end side than the support shaft 10b. The crushing claw 10a is formed by the hydraulic cylinder 10c for the crusher. , 10a are driven to open and close.

On the other hand, the breaker 11 has a structure as shown in FIG. That is, a cylinder 11b is formed in the breaker body 11a, a piston 11c is slidably mounted in the cylinder 11b, and a rod 11d is provided to protrude from the breaker body 11a to reciprocate the piston 11c. The rod 11d
It is configured to apply a blow to the. Piston 1
The supply port 11e and the discharge port 11f and the reciprocating switching valve 11g are used to reciprocate the breaker body 1c.
1a, the supply port 11e, the discharge port 11f, the cylinder 11b, and the reciprocating switching valve 11g.
Are connected with a plurality of oil passages. Therefore, the pressure oil supplied from the supply port 11e causes the piston 1
1c slides in the cylinder 11b. During this reciprocating stroke, the reciprocating switching valve 11g controls the rear and front piston chambers, the supply port 11e and the discharge port 1e.
1f is switched.

As described above, the crusher 10 and the breaker 1
Numerals 1 are both hydraulically driven, but the hydraulic cylinder 9 for the bucket is for operating the front link mechanism as described above.
In order to supply pressurized oil to the crusher hydraulic cylinder 10c and the supply port 11e of the breaker 11, the first
The hydraulic pipes 12a and 12b from the directional control valve group 3b constituting the directional control valve group 3 are detachable from the rod chamber and the bottom chamber of the crusher hydraulic cylinder 10c and the supply port 11e and the discharge port 11f of the breaker 11. It can be connected to.

When the crusher 10 is operated in the closing direction, that is, at the time of crushing, a large flow rate is required in order to perform the operation at a high speed. Not only the pressure oil supplied from the pump 1 but also the pressure oil from the second hydraulic pump 2 is merged. On the other hand, the breaker 11 is driven only by the first hydraulic pump 1 because it does not require a large flow rate. However, the breaker 11 has a possibility that dust or foreign matter from the outside may enter.
Return oil from the discharge port 11f is returned directly to the hydraulic oil tank 15 via the filter 14 by the return pipe 13 without passing through the direction switching valve 3b.

[0012] In view of the above requirements, a merging control means and a flow path switching means are provided. The merging control means is provided in the center bypass flow passage 16 connected to the second hydraulic pump 2.
An on-off valve 17 is provided at a position downstream of the directional control valve group 4, and a merging pipe 18 is connected to a position upstream of the on-off valve 17 and downstream of the second directional control valve group 4. ,
The merging pipe 18 is configured to be connected to the supply port of the direction switching valve 3b of the first direction switching valve group 3. The on-off valve 17 joins the hydraulic oil from the first and second hydraulic pumps 1 and 2 only when the crusher 10 is attached and the crusher 10 is operated in the closing direction. Therefore, a pilot flow path opening / closing valve 19 is provided in a pilot flow path 19a for supplying / cutting off the pilot pressure to the opening / closing valve 17, and this pilot flow path 19a is provided for operating the direction switching valve 3b. The closing direction of the crusher 10 among the pilot pipes 20a and 20b connecting the operation lever 20 and both pilot portions of the direction switching valve 3b,
That is, it is in communication with the pilot pipe 20b in the closing direction of the crusher hydraulic cylinder 10c. Accordingly, if the pilot flow opening / closing valve 19 is opened, the pilot operation valve 2
When 0 is operated and pressure is generated in the pilot pipe 20b, the on-off valve 17 is closed in conjunction therewith, and the pressure oil from the second hydraulic pump 2 joins.

The flow path switching means comprises a switching valve 21, which is connected to the discharge port 1 of the breaker 11.
1f is connected to the directional control valve 3
This is for switching from the state connected to b to the state connected to the return pipe 13. This switching valve 21
, The hydraulic pipe 12b can be switched from the return pipe 13 to the flow path returning to the hydraulic oil tank 15 via the filter 14.

In the above configuration, the pilot flow path opening / closing valve 19 forming the merging control means and the switching valve 21 forming the flow path switching means can be switched manually. Therefore, when the crusher 10 is mounted, the pilot flow path opening / closing valve 19 is opened, and the return valve 13 of the switching valve 21 is connected to the direction switching valve 3b. Thereby, when the crusher 10 operates in the closing direction, the crusher is in the crusher operation mode in which the first and second hydraulic pumps 1 and 2 join. When the breaker 11 is attached, the pilot flow path on-off valve 19 is closed, and the switching valve 21 switches to a state in which the hydraulic pipe 12 b communicates with the return pipe 13. As a result, there is no merging from the second hydraulic pump 2 and the discharge port 11 of the breaker 11
f returns to the hydraulic oil tank 1 via the filter 14.
5 is set to the breaker operation mode.

[0015]

By the way, the pilot flow passage opening / closing valve 19 constituting the merging control means and the switching valve 21 constituting the flow passage switching means are operated independently of each other. When switching between the machine operation mode and the breaker operation mode, the pilot flow path on-off valve 19 and the switching valve 21 must be operated without fail. Here, since the pilot flow opening / closing valve 19 is interposed in the flow path between the pilot operation valve 20 and the second direction switching valve group 4, it is located near the pilot operation valve 20, that is, the pilot operation valve 20. It is possible to arrange it in the cab.
However, although the switching valve 21 is provided at an intermediate position of the return pipe 13, since the return pipe 13 is not routed into the cab, it is provided outside the cab, that is, the second direction switching valve group 3 is disposed. Generally, it is provided near the position.

From the above, when switching between the crusher operation mode and the breaker operation mode,
Since it is necessary to operate the pilot flow path on-off valve 19 and the switching valve 21 at positions separated from each other, this switching operation is not only troublesome, but also due to carelessness and the like.
There is a risk that one or both switching operations may be neglected. Further, since the switching valve 21 cannot be provided in the cab, the operator neglected to operate and check the switching valve 21 because of the troublesomeness of going out of the cab and performing the confirmation, and the return pipe 13 was moved in the direction. In spite of being connected to the flow path on the switching valve 3b side, there is a possibility that a situation may occur in which the breaker 11 is activated by overlooking it. In this case, since the return oil containing the foreign matter flows into the directional control valve 3b, inconveniences such as damage to the directional control valve 3b occur.

The present invention has been made in view of the above points, and it is an object of the present invention to easily and reliably switch between a crusher operation mode and a breaker operation mode. Moreover, it is an object of the present invention to easily confirm which operation mode is currently set.

[0018]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention relates to a hydraulic excavator having a front link mechanism provided with a hydraulic fluid from a first hydraulic pump and a second hydraulic pump when the crusher is mounted on the front link mechanism. And when the breaker is attached, the joining control means for controlling the joining of the pressure oil from the second hydraulic pump to be prevented, and the return oil from the crusher and the breaker are attached to the crusher. Flow path switching means for returning directly to the hydraulic oil tank via a filter without passing through the direction switching valve via the direction switching valve and when the breaker is mounted, and two hydraulic pumps in the merge control means. A crusher operation mode in which the pressurized oil is merged and the return oil is returned to the hydraulic oil tank via the direction switching valve by the flow path switching means;
And return oil is returned by the flow path switching means.
Breaker operation mode that returns to the hydraulic oil tank through the filter
And an operation mode switching means for switching the operation mode .

[0019]

When the crusher operation mode is selected by operating the operation mode switching means, the first and second hydraulic pumps are brought into a combined state by the joining control means, and the return pipe is switched by the flow switching means to the direction switching valve. Will be connected. Thereby, in the closing direction of the crusher, the pressure oil from the second hydraulic pump merges with the pressure oil from the first hydraulic pump and is supplied to the crusher hydraulic cylinder in a state where the flow rate is increased. become able to. Also, in order to operate the hydraulic cylinder in the extending direction and the contracting direction, the return oil needs to be returned to the hydraulic oil tank through the direction switching valve.
The return pipe is returned to the hydraulic oil tank via the direction switching valve.

On the other hand, when the breaker operation mode is selected, both the merging control means and the flow path switching means are switched, and
There is no merging from the second hydraulic pump, and the return pipe is returned to the hydraulic oil tank via the filter. As a result, the return oil, which is highly likely to be contaminated by foreign matter through the breaker, is returned to the hydraulic oil tank with the foreign matter completely removed by the filter, preventing damage to the directional control valve and the like. become able to.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As is clear from FIG. 1, the basic configuration of the hydraulic circuit is not particularly different from that of the above-described prior art. Therefore, members that are the same as or equivalent to those of the related art are given the same reference numerals, and descriptions thereof are omitted.

Thus, the pilot passage opening / closing valve 30 constituting the merging control means and the switching valve 3 constituting the flow passage switching means
1 are both switched by a hydraulic pilot system, and normally, return springs 30a, 30
The state shown in the figure is maintained by the action of 1a.

In this state, the pilot flow switching valve 30
Is held in a state in which the pilot flow path 30c is shut off. Therefore, even if the pilot operation valve 20 is operated in any direction to generate pressure in the pilot pipe, the pressure acts on the hydraulic pilot portion of the on-off valve 17. Nothing. For this reason, the center bypass flow path 16 is held in a state of communicating with the hydraulic oil tank 15, and no pressure oil is supplied to the merge pipe 18. In a state where not switch any of the directional control valve the directional control valve 4a~4d constituting the second directional control valve group 4, the second hydraulic pump 2 through communication with the hydraulic oil tank 15
You .

On the other hand, the switching valve 31 is in a state in which the hydraulic pipe 12 b communicates with the return pipe 13. Therefore, the return oil flows from the return pipe 13 via the filter 14 to the hydraulic oil tank 1.
It will be returned to 5.

In the above state, the breaker 11 is attached to the front link mechanism, and a breaker operation mode is set in which the breaker 11 can be operated. By the way, when neither the breaker 11 nor the crusher 10 is attached to the hydraulic pipes 12a and 12b from the direction switching valve 3b,
Since return oil does not flow, the switching valve 31 does not cause any particular problem regardless of the switching position. However,
Unless the on-off valve 17 provided in the center bypass passage 16 is kept open, the second hydraulic pump 2 does not enter the no-load operation state. Therefore, the breaker 11 is also the crusher 1
When 0 is not attached, the breaker operation mode may be set to this breaker operation mode , and in this regard, the breaker operation mode doubles as the non-operation mode.

When the crusher 10 is mounted, the pilot operation valve 20
The pressure in one of the pilot pipes 20b is guided to the pilot portion of the on-off valve 17 via the pilot pipe 30c, the on-off valve 17 is closed, and the pressure oil from the second hydraulic pump 2 is supplied to the junction pipe 18. In the switching valve 31, it is necessary to keep the hydraulic pipe 12b in communication with the return pipe 13 and to connect the hydraulic pipe 12b to the direction switching valve 3b. For this purpose, the pilot passage opening / closing valve 30 and the switching valve 31 are provided with a hydraulic pilot unit 30.
b, 31b are provided.
When the pressure oil is supplied to the pilot flow passages 0b and 31b, the pilot flow path on-off valve 30 and the switching valve 31 are returned to the return springs 30a and 31b.
The state is switched to the above-mentioned state against a. This is the crusher operation mode.

An operation mode switching means 32 is provided to switch from the breaker operation mode to the crusher operation mode and vice versa to switch from the crusher operation mode to the breaker operation mode. The operation mode switching means 32 has an electromagnetic switching valve 33, and can supply the pressure oil from the auxiliary hydraulic pump 34 to the pilot operation valve 20 and the like via the electromagnetic switching valve 33.

The pilot flow path opening / closing valve 30 and the switching valve 31
The hydraulic pilot units 30b and 31b are connected to the electromagnetic switching valve 33 so that the hydraulic pilot units 30b and 31b
b and 31b are switched between a state in which they are connected to the hydraulic oil tank 15 and a state in which they are connected to the auxiliary hydraulic pump. Electromagnetic pilot part 33 of electromagnetic switching valve 33
In order to excite a, a switch 35 is provided,
Therefore, this switch 35 functions as a switching operation section of the operation mode switching means 32.

Normally, this switch 35 is
In this state, the hydraulic pilot sections 30b and 31b are in communication with the hydraulic oil tank 15, and the pilot flow path on-off valve 30 and the switching valve 31 are returned to the return spring 30.
The breaker operation mode shown in FIG.

When the switch 35 is turned on, the electromagnetic pilot section 33a is excited, the electromagnetic switching valve 33 is switched, and the hydraulic pilot sections 30b and 31b are connected to the auxiliary hydraulic pump 34. The pressure oil from the pump 34 is supplied to the hydraulic pilot portions 30b and 31b of the pilot flow path on-off valve 30 and the switching valve 31, and the pilot flow path on-off valve 30 and the switching valve 31 oppose the return springs 30a and 31a. To the crusher operation mode.

Here, a signal line 36 is connected to the switch 35.
As shown in FIG. 2, the signal line 36 is connected to a display panel 37 constituting a mode display means. The display panel 37 includes a switch 35
Together with the breaker operating mode 37a or the crusher operating mode 37b.

With the above configuration, when the breaker 11 is mounted on the front link mechanism, the switch 35 is turned off to open the on-off valve 17 and the center of the second hydraulic pump 2 The bypass flow path 16 is maintained in a state of communicating with the hydraulic oil tank 15, no pressurized oil is supplied to the junction pipe 18, and the switching valve 3
Due to 1, the hydraulic pipe 12b does not communicate with the direction switching valve 3b, but communicates from the return pipe 13 to the hydraulic oil tank 15 via the filter 14. Thereby, when the breaker 11 is operated, the pressure oil from the first hydraulic pump 1 is supplied to the breaker 11 and the operation is performed, and the entire amount of the return oil from the discharge port 11f is returned to the return pipe 13. From the filter 1 through the filter 14, and this filter 1
4 removes foreign matter.

Further, the breaker 1 is provided in the front link mechanism.
When the crusher 10 is mounted in exchange for 1, the operator turns on the switch 35 in the cab. As a result, both the pilot flow path on-off valve 30 and the switching valve 31 are switched to the crusher operation mode. In this crusher operation mode, when the crusher 10 is operated in the closing direction by the pilot operation valve 20, this operation is detected by the pilot flow opening / closing valve 30, and the opening / closing valve 17 is closed. Since the pressurized oil from the first and second hydraulic pumps 1 and 2 is combined and supplied to the crusher hydraulic cylinder 10c, the supply flow rate increases, and a high-speed closing operation is realized. be able to. Further, since the hydraulic cylinder 10c for the crusher operates in both extension and contraction, in order to enable the operation in both directions, the hydraulic pipe 12b is connected to the direction switching valve 3b together with the hydraulic pipe 12a. Become.

Further, not only the crusher 10 and the breaker 11 but also other front attachments are attached to the front link mechanism. Of course, a bucket or the like is also attached to the front link mechanism, but the bucket or the like does not have a hydraulic actuator itself, and therefore, the hydraulic pipes 12a and 12b are not connected to the hydraulic actuator. Also in this case, the breaker operation mode is selected as the operation mode.

As described above, the operator operates the switch 35 in the operator's cab to operate the switch 35 and the pilot flow path on-off valve 30 and the switching valve 31 in a state suitable for operating the crusher 10 together. , Can be switched to a state suitable for operating the breaker 11.
Further, since the operation mode can be confirmed in the cab, the breaker 11 is operated, for example, in a state in which the hydraulic pipe 12b is in communication with the direction switching valve 3b, and the return oil containing foreign matter enters the direction switching valve 3b. There is no risk of getting in.

In the above embodiment, the display panel for displaying the operation mode is provided. However, depending on the state of the switch, the operation mode is the crusher operation mode or the breaker operation mode. It is not always necessary to provide a display means as long as the display means can be identified. In addition, the pilot passage opening / closing valve 30 and the switching valve 31 are of a hydraulic pilot type, but may be of an electromagnetic operation type.
When the switch is turned on, a current may be passed directly from the power supply to those electromagnetic pilot sections.

[0037]

According to the present invention, as described above, the operation mode is switched off.
By operating the switching means, the merging control means
Pressure oil from the hydraulic pump of
Crushed return oil is returned to the hydraulic oil tank via the directional valve
Machine operation mode and the merging control means
Confluence is prevented and return oil is filled by the flow path switching means.
The mode is switched to the breaker operation mode for returning to the hydraulic oil tank via the filter, so that the switching between the crusher operation mode and the breaker operation mode can be easily and reliably performed. It is possible to easily confirm which operation mode is set.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a hydraulic circuit of a hydraulic shovel showing one embodiment of the present invention.

FIG. 2 is a configuration explanatory view showing an example of an operation mode display means.

FIG. 3 is a circuit configuration diagram of a hydraulic circuit of a conventional hydraulic shovel.

FIG. 4 is a longitudinal sectional view of a breaker.

[Explanation of symbols]

 1, 2 hydraulic pump 3, 4 direction switching valve group 3a to 3e, 4a to 4d direction switching valve 10 crusher 11 breaker 12a, 12b hydraulic piping 13 return piping 14 filter 15 hydraulic oil tank 17 on / off valve 18 merge piping 20 pilot operation Valves 20a, 20b Pilot piping 30 Pilot flow path opening / closing valve 31 Switching valve 30a, 31a Return spring 30b, 31b Hydraulic pilot section 32 Operating mode switching means 33 Electromagnetic switching valve 34 Auxiliary hydraulic pump 35 Switch 37 Display panel

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) E02F 9/22 E02F 9/20

Claims (3)

(57) [Claims] A first hydraulic circuit including a first hydraulic pump and a first directional control valve group including a plurality of directional control valves for controlling supply of pressure oil from the first hydraulic pump; A second hydraulic circuit including a second hydraulic pump and a second directional switching valve group including a plurality of directional switching valves for controlling the supply of pressure oil from the second hydraulic pump; A hydraulic excavator in which a crusher and a breaker are interchangeably mounted on a link mechanism, wherein when the crusher is mounted, the hydraulic oil from the first and second hydraulic pumps is merged. When the crusher is mounted, the return oil from the crusher and the breaker controls the direction switch valve when the crusher is mounted. Through and also blur At the time of installation of the mosquito, the flow path switching means for returning directly to the hydraulic oil tank via a filter without passing through the direction switching valve, A crusher operation mode in which the return oil is returned to the hydraulic oil tank via the direction switching valve in the flow path switching means, and the two hydraulic pumps in the merge control means.
Are prevented from being joined, and the return
Fluctuation of oil returning to the hydraulic oil tank through the filter
An operation mode that switches the operation mode between the marker operation mode and
A hydraulic circuit for a hydraulic shovel, comprising a switching unit . 2. The hydraulic circuit for a hydraulic shovel according to claim 1, wherein said operation mode switching means is disposed in a cab. 3. The hydraulic excavator according to claim 2, further comprising mode display means for displaying which operation mode the operation mode switching means is in, together with the operation mode switching means. circuit.