JPH08199632A - Oil hydraulic circuit for hydraulic shovel - Google Patents

Abstract

PURPOSE: To provide an oil hydraulic circuit which can easily and surely carry out a changeover between a crusher actuating mode and a braker actuating mode, and moreover can easily confirm which actuating mode is functioning now. CONSTITUTION: A pilot flow path switch valve 30 composing a confluence control means and a directional control valve 31 composing a flow path changing means are changed over through hydraulic pilot system, and at ordinary times, severally maintained in a braker actuating mode by reset springs 30a, 31a. In order to change over a changing valve for these pilot flow path switch valve into a crusher actuating mode, an actuating mode changing over means 32 composed of a solenoid change over valve 33 and a switch functioning as its changing over operation section is provided. When an operator turns on the switch 35, pressure oil is supplied from an auxiliary hydraulic pump 34 to the pilot flow path switch valve 30 and the hydraulic pilot parts 30b, 31b of the directional control valve 31, and thereby changed over into the crusher actuating mode. The actuating mode can be confirmed by visual observation on a display panel 37.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In a hydraulic excavator, an upper revolving structure is rotatably mounted on a lower traveling structure having a crawler belt, and an operating room and a front working mechanism are provided on the upper revolving structure. The front working mechanism connects the boom to the upper swing body so that the boom can be lifted and lowered, the arm is pivotally connected to the tip of the boom so as to be vertically rotatable, and the front link mechanism is provided at the tip of the arm. A front attachment is detachably connected to the front link mechanism.
A typical front attachment is a bucket for work such as excavation of earth and sand. In addition to this bucket, for example, a crusher or a breaker is attached.

A hydraulic actuator is mounted for running, turning, and operating the front working mechanism of the hydraulic excavator. That is, the traveling and turning are driven by the hydraulic motor, and the operation of the front working mechanism is driven by the hydraulic cylinder. As a hydraulic circuit for driving the hydraulic actuator composed of these hydraulic motor and hydraulic cylinder, FIG. Conventionally, the structure shown in FIG.

This hydraulic circuit is provided with first and second hydraulic pumps 1 and 2, and these first and second hydraulic pumps 1 and 2 are respectively composed of a plurality of directional switching valves.
The second directional control valve groups 3 and 4 are connected. A hydraulic actuator is connected to each of the directional control valves forming the first and second directional control valve groups 3 and 4.
By performing the switching operation of the direction switching valve, pressure oil is supplied to each hydraulic actuator, and each hydraulic actuator is driven. Each direction switching valve is provided with a pair of pilot portions, and when a pilot signal is supplied to any of these pilot portions,
Pressure oil from the hydraulic pumps 1 and 2 is supplied to the hydraulic actuator. And, in order to supply a pilot signal to each direction switching valve, a pilot operated valve is provided in the cab.

As hydraulic actuators constituting the hydraulic excavator, 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 are provided. ing. Here, since the boom hydraulic cylinder 7 and the arm hydraulic cylinder 8 require a large flow rate, the pressure oils from the hydraulic pumps 1 and 2 are combined.

In the illustrated hydraulic circuit, the first directional switching valve group 3 connected to the first hydraulic pump 1 has 5
The individual directional control valves 3a to 3e are connected, and the second
Second directional control valve group 4 connected to the hydraulic pump 2 of
Is connected to four directional control valves 4a-4d. First
Of the directional control valve group 3 is a traveling hydraulic motor 5a, the directional control valve 3c is a boom hydraulic cylinder 7 and the directional control valve 3d is an arm hydraulic cylinder 8.
Further, the direction switching valve 3e is connected to the turning hydraulic motor 6. Further, the direction switching valve 4a constituting the second direction switching valve group 4 is used for the traveling hydraulic motor 5b, the direction switching valve 4b is used for the bucket hydraulic cylinder 9, and the direction switching valve 4c is used for the boom hydraulic cylinder 7. 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.

The front link mechanism includes a crusher 10
Also, the breaker 11 is detachably connected. And, the crusher 10 and the breaker 11 are
It is designed to be hydraulically driven.

The crushing machine 10 has a pair of crushing claws 10a, 10a as shown in the drawing, and the crushing claws 10a, 10a.
Is rotatably attached to a support shaft 10b, and a hydraulic cylinder 10c for a crusher is connected to a portion of the base end side of the support shaft 10b. The crusher claw 10a is connected 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, the cylinder 11b is formed in the breaker body 11a, the piston 11c is slidably mounted in the cylinder 11b, and the rod 11d is provided so as to project from the breaker body 11a to reciprocate the piston 11c. By making the rod 11d
It is configured to give a blow to. Piston 1
In order to reciprocate 1c, supply port 11e and discharge port 11f, and reciprocation switching valve 11g are provided in breaker body 1
1a, the supply port 11e, the discharge port 11f, the cylinder 11b, and the reciprocating motion switching valve 11g.
A plurality of oil passages are connected between and. Accordingly, the pressure oil supplied from the supply port 11e causes the piston 1
1c slides in the cylinder 11b, and during this reciprocating stroke, the reciprocating switching valve 11g causes the piston rear chamber and the piston front chamber, and the supply port 11e and the exhaust port 1 to move.
The connection state with 1f is switched.

As described above, the crusher 10 and the breaker 1
1 is hydraulically driven together, but the bucket hydraulic cylinder 9 is for operating the front link mechanism as described above, and therefore, the crusher 1
In order to supply pressure oil to the crusher hydraulic cylinder 10c and the supply port 11e of the breaker 11,
The hydraulic pipes 12a and 12b from the directional control valve 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. You can connect to.

By the way, 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 high speed. Therefore, in order to increase the flow rate of the pressure oil, the first hydraulic pressure is applied. Not only the pressure oil supplied from the pump 1 but also the pressure oil from the second hydraulic pump 2 is combined. On the other hand, the breaker 11 does not require such a large flow rate, and is therefore driven only by the first hydraulic pump 1. However, since the breaker 11 may intrude dust or foreign matter from the outside,
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.

From the above requirements, the merging control means and the flow path switching means are provided. The merging control means is the second bypass in the center bypass passage 16 connected to the second hydraulic pump 2.
An on-off valve 17 is provided at a position downstream of the direction switching 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 direction switching valve group 4. ,
The merging pipe 18 is connected to the supply port of the directional control valve 3b of the first directional control valve group 3. The on-off valve 17 joins the pressure oils 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 passage opening / closing valve 19 is provided in a pilot flow passage 19a for supplying / shutting off pilot pressure to / from the opening / closing valve 17, and this pilot flow passage 19a is provided for operating the direction switching valve 3b. Of the pilot pipes 20a, 20b connecting the operating lever 20 and both pilot portions of the direction switching valve 3b, the closing direction of the crusher 10,
That is, it communicates with the pilot pipe 20b in the closing direction of the crusher hydraulic cylinder 10c. Therefore, if the pilot passage 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 open / close valve 17 is opened in conjunction with the pressure, and the pressure oil from the second hydraulic pump 2 joins.

The flow path switching means is composed of a switching valve 21, and this switching valve 21 is the discharge port 1 of the breaker 11.
1f is connected to the hydraulic pipe 12b, the direction switching 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
By switching the above, the hydraulic pipe 12b can be switched from the return pipe 13 to the flow path for returning to the hydraulic oil tank 15 via the filter 14.

In the above structure, the pilot passage opening / closing valve 19 forming the merging control means and the switching valve 21 forming the passage switching means can be switched manually. Therefore, when the crusher 10 is attached, the pilot passage opening / closing valve 19 is opened, and the switching valve 21 brings the return pipe 13 into communication with the directional switching valve 3b. As a result, when the crusher 10 operates in the closing direction, the crusher operation mode in which the first and second hydraulic pumps 1 and 2 join together is set. Further, when the breaker 11 is attached, the pilot passage opening / closing valve 19 is closed and the switching valve 21 switches to a state in which the hydraulic pipe 12b 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
Return oil from f is passed through the filter 14 to the hydraulic oil tank 1
The breaker operation mode is returned to 5.

[0015]

By the way, the pilot flow passage opening / closing valve 19 and the switching valve 21 constituting the flow passage switching means, which constitute the above-mentioned merging control means, are operated independently of each other, and are crushed. When switching between the machine operating mode and the breaker operating mode, the pilot flow passage opening / closing valve 19 and the switching valve 21 must be operated. Here, since the pilot flow passage opening / closing valve 19 is provided in the flow passage between the pilot operation valve 20 and the second directional control valve group 4, it is provided near the pilot operation valve 20, that is, It is possible to place it in the cab.
However, the switching valve 21 is provided at an intermediate position of the return pipe 13, but since the return pipe 13 is not routed inside the driver's cab, it is arranged outside the driver's cab, that is, the second directional control valve group 3 is disposed. It is generally 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 passage opening / closing valve 19 and the switching valve 21 that are located apart from each other, this switching operation is not only troublesome, but also due to carelessness,
One or both switching operations may be neglected. Further, since the switching valve 21 cannot be provided in the driver's cab, the operator neglects to operate and check the switching valve 21 due to the inconvenience of getting out of the driver's cab and checking it. Despite the fact that the breaker 11 is connected to the flow path on the side of the switching valve 3b, the breaker 11 may be operated by overlooking it. In this case, the return oil mixed with foreign matter flows to the direction switching valve 3b, which causes a problem such as damage to the direction switching valve 3b.

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

[0018]

In order to achieve the above-mentioned object, the present invention provides pressure oil from first and second hydraulic pumps when a crusher is attached to a front link mechanism of a hydraulic excavator. And the breaker is attached, the merging control means for controlling so as to prevent the merging of the pressure oil from the second hydraulic pump and the return oil from the crusher and the breaker are attached to the crusher. And a flow path switching means for returning directly to the hydraulic oil tank via a filter, not through the direction switching valve when the breaker is attached, and through the direction switching valve, and these merge control means and flow path switching means. Is provided with an operation mode switching means for collectively switching.

[0019]

When the operation mode switching means is operated to select the crusher operation mode, the merging control means brings the first and second hydraulic pumps into a merging state, and the flow passage switching means causes the return pipe to turn the direction switching valve. Will be connected to. As a result, 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 to increase the flow rate and supply it to the crusher hydraulic cylinder. become able to. In addition, in order to operate this hydraulic cylinder in the expansion direction and the contraction direction, the return oil must be returned to the hydraulic oil tank through the direction switching valve,
The return pipe is returned to the hydraulic oil tank via the directional control 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,
The merging from the second hydraulic pump is eliminated, and the return pipe is returned to the hydraulic oil tank via the filter. As a result, through the breaker, the return oil that is likely to contain foreign matter is returned to the hydraulic oil tank with the foreign matter completely removed by the filter, preventing damage to the directional control valve and other factors. become able to.

[0021]

Embodiments of the present invention will be described below with reference to FIGS. As is apparent from FIG. 1, the basic configuration of the hydraulic circuit does not differ from that of the above-described conventional art. Therefore, the same or equivalent members as those of the configuration of the conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

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

In this state, the pilot passage opening / closing valve 30
Is held in a state of shutting off the pilot flow passage 32, and therefore no matter which direction the pilot operation valve 20 is operated to generate pressure in the pilot pipe, the pressure acts on the hydraulic pilot portion of the opening / closing valve 17. Never. For this reason, the center bypass flow passage 16 is maintained in a state of communicating with the hydraulic oil tank 15, and pressure oil is not supplied to the merging pipe 18. When the second hydraulic pump 2 does not switch any of the directional switching valves 4a to 4d forming the second directional switching valve group 4, the second hydraulic pump 2 is connected to the hydraulic oil tank 15. They are in communication with each other, and the directional control valves 4a-
Even if any of 4d is switched, no pressure is generated on the upstream side of the second directional control valve group 4.

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

In the above-mentioned state, the breaker 11 is attached to the front link mechanism, and the breaker operation mode in which the breaker 11 can be operated is set. 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 the return oil does not flow, there is no particular problem with the switching valve 31 at any switching position. However,
The second hydraulic pump 2 does not enter the no-load operation state unless the open / close valve 17 provided in the center bypass flow path 16 is kept open. Therefore, the breaker 11 is also the crusher 1.
When 0 is not attached, the breaker operating mode may be set, and in this respect, the breaker operating mode also serves as the non-operating mode.

When the crusher 10 is installed, the pilot operation valve 20 is opened by the pilot passage opening / closing valve 30.
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 merging pipe 18. This is not possible, and in the switching valve 31, it is necessary that the hydraulic pipe 12b is not communicated with the return pipe 13 and the hydraulic pipe 12b is communicated with the direction switching valve 3b. For this reason, the pilot flow passage opening / closing valve 30 and the switching valve 31 have the hydraulic pilot portion 30.
b and 31b are provided, and the hydraulic pilot unit 3
When the pressure oil is supplied to 0b and 31b, the pilot flow passage opening / closing valve 30 and the switching valve 31 are returned to the return springs 30a and 31b.
The state described above is switched against a. This is the crusher operating mode.

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

Pilot channel opening / closing valve 30 and switching valve 31
The hydraulic pilot portions 30b and 31b of the hydraulic pilot portion 30 are connected to the electromagnetic switching valve 33.
b and 31b can be switched between a state in which they communicate with the hydraulic oil tank 15 and a state in which they are connected to the auxiliary hydraulic pump 34. Electromagnetic pilot part 33 of electromagnetic switching valve 33
A switch 35 is provided to excite a.
Therefore, the switch 35 functions as a switching operation portion of the operation mode switching means 32.

Normally, this switch 35 is OF
In the F state, the hydraulic pilot portions 30b and 31b communicate with the hydraulic oil tank 15 in this state, and the pilot passage opening / closing valve 30 and the switching valve 31 are in the return spring 30.
The breaker operation mode shown in the figure is achieved by the action of a and 31a.

When the switch 35 is turned on, the electromagnetic pilot portion 33a is excited, the electromagnetic switching valve 33 is switched, and the hydraulic pilot portions 30b and 31b come into communication with 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 passage opening / closing valve 30 and the switching valve 31 so that the pilot passage opening / closing valve 30 and the switching valve 31 resist the return springs 30a and 31a. To the crusher operation mode.

The switch 35 has a signal line 36.
2 is connected to the signal line 36. As shown in FIG. 2, the signal line 36 is connected to a display panel 37 which constitutes a mode display means. This display panel 37 has a switch 35.
It is arranged in the driver's cab together with the breaker operating mode 37a or the crusher operating mode 37b to light up.

With the above structure, when the breaker 11 is attached to the front link mechanism, the switch 35 is turned off to open the on-off valve 17 and open the center from the second hydraulic pump 2. The bypass passage 16 is maintained in a state of communicating with the hydraulic oil tank 15, pressure oil is not supplied to the merging pipe 18, and the switching valve 3
1, the hydraulic pipe 12b is not connected to the direction switching valve 3b, but is connected to the hydraulic oil tank 15 from the return pipe 13 via the filter 14. As a result, when the breaker 11 is operated, the pressure oil from the first hydraulic pump 1 is supplied to the breaker 11 to operate, and the entire amount of return oil from the discharge port 11f is returned to the return pipe 13 Flow through the filter 14 from this filter 1
Foreign matter is removed by 4.

Further, the breaker 1 is attached to the front link mechanism.
When the crusher 10 is attached after being replaced with 1, the operator turns on the switch 35 in the cab. As a result, both the pilot flow passage opening / closing valve 30 and the switching valve 31 are switched to the crusher operation mode. In this crusher operation mode, when the pilot operating valve 20 operates the crusher 10 in the closing direction, this operation is detected by the pilot flow passage opening / closing valve 30 and the opening / closing valve 17 is closed. Since the pressure oil from the first and second hydraulic pumps 1 and 2 joins and is supplied to the crusher hydraulic cylinder 10c in FIG. 1, the supply flow rate increases, and a high-speed closing operation is realized. be able to. Further, since the crusher hydraulic cylinder 10c operates both for extension and contraction, the hydraulic pipe 12b is connected to the direction switching valve 3b together with the hydraulic pipe 12a in order to enable the operation in both directions. 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 this bucket or the like does not have a hydraulic actuator in 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 stays in the operator's cab and operates the switch 35 in a single action so that the pilot passage opening / closing valve 30 and the switching valve 31 are put together into a state suitable for operating the crusher 10. , It is possible to switch to a state suitable for operating the breaker 11.
Further, since this operation mode can be confirmed in the operator's cab, for example, the breaker 11 is operated in a state where the hydraulic pipe 12b communicates with the directional control valve 3b, so that the return oil mixed with the foreign matter enters the directional control valve 3b. There is no danger of getting in.

Although the display panel for displaying the operation mode is provided in the above-mentioned embodiment, whether the operation mode is the crusher operation mode or the breaker operation mode is set depending on the state of the switch. If it is possible to identify, it is not always necessary to provide a display means. Further, although the pilot passage opening / closing valve 30 and the switching valve 31 are hydraulic pilot systems, they may be electromagnetically operated systems. If such electromagnetically operated systems are used,
When the switches are turned on, a current may be passed from the power source directly to those electromagnetic pilot portions.

[0037]

As described above, according to the present invention, the merging control means and the flow path switching means are collectively switched by the operation mode switching means, so that the crusher operation mode and the breaker operation mode are switched. It is possible to easily and surely perform the switching of the above, and it is possible to easily confirm which operation mode is currently set.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a hydraulic circuit of a hydraulic excavator showing an embodiment of the present invention.

FIG. 2 is a structural explanatory view showing an example of an operating mode display means.

FIG. 3 is a circuit configuration diagram of a hydraulic circuit of a hydraulic excavator according to a conventional technique.

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

[Explanation of symbols]

 1, 2 Hydraulic pumps 3, 4 Directional switching valve groups 3a to 3e, 4a to 4d Directional switching valves 10 Crushers 11 Breakers 12a, 12b Hydraulic piping 13 Return piping 14 Filters 15 Hydraulic oil tanks 17 Open / close valves 18 Combined piping 20 Pilot operation Valves 20a, 20b Pilot piping 30 Pilot flow passage opening / closing valve 31 Switching valve 30a, 31a Return spring 30b, 31b Hydraulic pilot part 32 Operating mode switching means 33 Electromagnetic switching valve 34 Auxiliary hydraulic pump 35 Switch 37 Display panel

Claims (3)

[Claims] 1. A first hydraulic circuit including a first hydraulic pump and a first directional control valve group including a plurality of directional control valves that control the supply of pressure oil from the first hydraulic pump, A second hydraulic circuit including a second hydraulic pump and a second directional control valve group including a plurality of directional control valves that control the supply of pressure oil from the second hydraulic pump; In a hydraulic excavator in which a crusher and a breaker are replaceably attached to the link mechanism, when the crusher is attached, the pressure oils from the first and second hydraulic pumps are combined, and the breaker is also attached. Is installed,
The merging control means for controlling the merging of the pressure oil from the second hydraulic pump and the return oil from the crusher and the breaker, when the crusher is attached, are passed through the directional control valve and the breaker. At the time of mounting, the flow path switching means for returning directly to the hydraulic oil tank through the filter without using the directional switching valve, and the operation mode switching means for collectively switching the joining control means and the flow path switching means. A hydraulic circuit for a hydraulic excavator, characterized in that 2. The hydraulic circuit for a hydraulic excavator according to claim 1, wherein the operation mode switching means is arranged in a driver's cab. 3. The hydraulic pressure of a hydraulic excavator according to claim 2, further comprising a mode display means for displaying which operation mode the operation mode switching means is in, together with the operation mode switching means. circuit.