JPH0720194Y2 - Hydraulic circuit of hydraulic shovel - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a hydraulic circuit of a hydraulic shovel in which a boom cylinder is configured to be driven by confluence of pressure oils of a plurality of hydraulic pumps.

[Conventional technology]

The hydraulic shovel supplies pressure oil from at least one hydraulic pump to the boom cylinder, and also supplies hydraulic oil from another hydraulic pump that supplies pressure oil to the swing motor for the boom raising operation. Some are equipped with a configuration. The hydraulic circuit of such a hydraulic shovel will be described with reference to FIG.

FIG. 3 is a circuit diagram of a part of a hydraulic circuit of a conventional hydraulic shovel. In the figure, 1A and 1B are hydraulic pumps, and 1C is a pilot pump. 2B ₁ and 2B ₂ are two boom cylinders, and 2M is a swing motor. 3B ₁ and 3B ₂ are directional control valves that control the drive of the boom cylinders 2B ₁ and 2B ₂ , and 3M is a directional control valve that controls the drive of the swing motor 2M. 4B is a boom cylinder 2B ₁ , 2B ₂
Pilot valve for operating, 4BL shows the operating lever. 4M is a pilot valve for operating the swing motor 2M, and 4ML is its operating lever. Reference numeral 5 is a relief valve that regulates the maximum pressure in the pilot line.

When the operation lever 4BL the pilot valve 4B is operated in the right side in FIG example, pilot pump 1C pilot pressure oil from the pilot valve 4B, the directional control valve 3B ₁ left pilot port and the direction of the switching valve 3B ₂ right pilot port Is supplied to. As a result, the direction switching valves 3B ₁ and 3B ₂ are switched, the pressure oil of the hydraulic pump 1A passes through the direction switching valve 3B ₁ , and
Pressure oil of the hydraulic pump 1B passes through the directional control valve 3B _2, and both of the pressure oil is joined is supplied to the bottom side of the boom cylinder 2B _1, 2B _2, allowed to increase the boom. On the other hand, when the operating lever 4BL is operated to the left, the directional switching valves 3B ₁ and 3B ₂ are switched in the opposite direction by the pressure oil of the pilot pump 1C, and the pressure oil of the hydraulic pump 1A switches the directional switching valve 3B ₁ . It is supplied to the rod side of the boom cylinders 2B ₁ and 2B ₂ to lower the boom. In this case, since the pressure oil of the hydraulic pump 1B is summer and structure the directional control valve 3B ₂ in its switching position be switched directional control valve 3B ₂ for preventing the pressure oil from the hydraulic pump 1B, the hydraulic pump Does not merge with 1A pressure oil. in this way,
Only when the boom is raised, the pressure oils of both hydraulic pumps 1A and 1B merge and are supplied to the boom cylinder, so that the boom rising speed is increased and the work efficiency is improved.

When the operating lever 4ML is operated, the pilot pump 1
The pressure oil of C is supplied to the pilot port on the corresponding side of the direction switching valve 3M, whereby the pressure oil of the hydraulic pump 1B is supplied to the swing motor 2M via the direction switching valve 3M, and this is operated in the operating direction of the operating lever 4ML. Rotate in the direction corresponding to.

Furthermore, if the operation lever 4BL is operated in the boom raising direction and the operation lever 4ML is operated in either direction at the same time,
The pressure oil of the hydraulic pump 1A is supplied to the boom cylinders 2B ₁ and 2B ₂ via the direction switching valve 3B ₁ as described above, and the pressure oil of the hydraulic pump 1B is respectively supplied via the direction switching valves 3M and 3B _2. It is supplied by being divided into the swing motor 2M and the boom cylinders 2B ₁ and 2B ₂ . Even in this case, the boom cylinders 2B ₁ , 2B ₂
The hydraulic oil from hydraulic pump 1A and the hydraulic oil split from hydraulic pump 1B are supplied to the bottom side of the joint, so the boom ascending speed is higher than when a single hydraulic pump is used. Efficiency is improved.

[Problems to be solved by the device]

There are various kinds of work for the hydraulic shovel, but a typical work is excavating earth and sand in a bucket and loading it into a dump truck. In this work, scoop earth and sand into the bucket, and operate the operation levers 4BL and 4ML as described above.
Swing motor 2M
The method of raising the boom while rotating the upper revolving structure of the hydraulic shovel is adopted. By this method,
When the bucket turns to the loading platform position of the dump truck, the bucket is already positioned at a height where soil can be dumped, and good work efficiency can be obtained.

By the way, the working conditions in the loading work are not constant, and for example, when the excavation depth of the hydraulic shovel is deep or shallow, or when the dump truck is on a ground higher than the hydraulic shovel or on a low ground. is there. And
Depending on these working conditions, there is a large difference in the amount of boom raising.

Here, in the case of a work that does not require a large amount of boom raising, for example, when the dump truck is on a low ground, the operation of the conventional combined operation of the hydraulic circuits will be considered.
Generally, the upper revolving structure of the hydraulic shovel driven by the revolving motor 2M has a large inertia, whereas the boom cylinder has a small inertia. Therefore, when the above combined operation is performed while the upper swing body is stationary, the load pressure of the hydraulic pump 1B is regulated by the pressures of the boom cylinders 2B ₁ and 2B ₂ , and most of the pressure oil is a boom cylinder with a small inertia. 2B ₁ and 2B ₂ are supplied, the load pressure of hydraulic pump 1B becomes low, and swing motor 2M
Is not accelerated enough. For this reason, the turning speed for turning the bucket to the position of the dump truck becomes slow, and it takes time to reduce the work efficiency, and the boom rising speed becomes large, causing the boom to excessively rise,
An operation to correct this is required. Further, when the operation of returning the direction switching valves 3B ₁ and 3B ₂ to the spool half position in order to suppress the excessive rise of the boom, a large loss occurs in hydraulic pressure.

As described above, the conventional hydraulic circuit has problems that work efficiency is lowered and operation is troublesome when performing work that does not require a large boom raising amount.

The object of the present invention is to solve the above-mentioned problems in the prior art,
(EN) Provided is a hydraulic circuit of a hydraulic shovel which can improve work efficiency and is easy to operate.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, a first aspect of the present invention provides a swing motor, a boom cylinder, at least one hydraulic pump for supplying pressure oil to each of these hydraulic actuators through a parallel pipe, and the boom cylinder. At least one hydraulic pump that supplies pressure oil through one pipeline, a first directional control valve that is interposed in each of the parallel pipelines and that drives and controls the swing motor, and a second directional control valve that drives and controls the boom cylinder. A directional control valve, a third directional control valve that intervenes in the one pipe line and drives the boom cylinder, a turning pilot valve that operates the first directional control valve, and the second directional control valve And a boom pilot valve for operating the third directional control valve, the hydraulic circuit of the hydraulic shovel comprising: when the swing pilot valve is operated; Characterized in that a switching inhibiting means for inhibiting the switching of the second directional control valve.

A second aspect of the present invention is characterized in that, in the first aspect, selection means is provided for selecting whether the switching prevention means is activated or inactivated.

[Action]

In the first invention, when the swing pilot valve is independently operated, the first direction switching valve is switched and the swing motor is driven by at least one hydraulic pump, and the boom pilot valve is independently operated, The second directional control valve and the third directional control valve are switched so that the boom cylinder is driven by the at least one hydraulic pump and the at least one other hydraulic pump. Also, when the turning pilot valve and the boom pilot valve are operated in combination,
The first directional switching valve and the third directional switching valve are switched, the switching blocking means is activated to block switching of the second directional switching valve, the swing motor is driven by the at least one hydraulic pump, and the boom is boomed. The cylinder is driven by the at least one other hydraulic pump.

Further, in the second invention, the selection means is operated according to the working condition to make the switching prevention means operable so as to prevent the switching of the second directional control valve during the combined operation or to operate the switching prevention means. In the disabled state, the second directional control valve can be constantly switched.

〔Example〕

 Hereinafter, the present invention will be described with reference to the illustrated embodiments.

FIG. 1 is a circuit diagram of a part of a hydraulic circuit of a hydraulic shovel according to a first embodiment of the present invention. In the figure, the same parts as those shown in FIG. 7 pilot valve 4B and the direction switching valve 3B ₂ of the right pilot port and the switching valve which is caused to intervene pilot conduit connecting the, 8 is the shuttle valve pilot pressure of the pilot valve 4M is introduced. The output port of the shuttle valve 8 is connected to the pilot port of the switching valve 7.

Next, the operation of this embodiment will be described. When the operating lever 4ML of the swing motor 2M is not operated, the pilot pressure is not generated on both sides of the pilot valve 4M, there is no output from the shuttle valve 8, and therefore the switching valve 7 is maintained at the position shown by the spring. . On the other hand, when the operating lever 4ML is operated to either side, the pilot pressure output from the pilot valve 4M is introduced into the pilot port of the switching valve 7 via the shuttle valve 8, and the switching valve 7 is left. It will be switched to the position.

Therefore, when the operating levers 4BL of the boom cylinders 2B ₁ and 2B ₂ are now independently operated, the switching valve 7 is at the position shown in the figure.
One output side of the pilot valve 4B is in a state of being connected to the pilot port of the directional switching valve 3B ₂ via the switching valve 7, and therefore the operation in this case is the same as that of the conventional hydraulic circuit shown in FIG. Same operation as boom cylinder 2B ₁ , 2B ₂
The hydraulic oils of the hydraulic pumps 1A and 1B are supplied to the hydraulic fluid in a combined manner.
Further, when the operation lever 4ML of the swing motor 2M is operated independently, the switching valve 7 is switched to the left position, but this switching has no relation to the pilot pipe line between the pilot valve 4M and the direction switching valve 3M. Therefore, the operation in this case is also the same as the operation of the conventional hydraulic circuit shown in FIG. 3, and the turning motor 2M is supplied with the pressure oil of the hydraulic pump 1B.

When performing boom raising operations at the same time while swinging the upper swing body of the hydraulic shovel, operating lever 4BL and operating lever 4
Combined operation with ML. In this case, since the pilot pressure is output from the pilot valve 4M, the direction switching valve 3M is switched and the switching valve 7 is switched to the left position in the drawing.
Boom cylinders 2B ₁ , 2B ₂ pilot valve 4B and directional valve 3
The pilot circuit to the right pilot port of B ₂ is cut off. Therefore, when the operation lever 4BL is operated to the right side in the figure by the above combined operation, the switching of the directional control valve 3B ₂ is blocked, and the directional control valve 3B ₂ remains in the neutral position. The direction switching valve 3B ₁ can be switched to the left side position as in the conventional case. By the above operation, only the pressure oil of the hydraulic pump 1A is supplied to the boom cylinders 2B ₁ and 2B _2, and the pressure oil of the hydraulic pump 1B is supplied to the swing motor 2M.

As described above, in this embodiment, during the combined operation of the swing of the upper swing body of the hydraulic shovel and the boom raising, only the pressure oil of one hydraulic pump is supplied to the boom cylinder, and the hydraulic pump on the side shared with the swing motor is supplied. Since the pressure oil is not supplied, the swing motor can be sufficiently accelerated, the swing time can be shortened, and the work efficiency can be improved. or,
Since the pressure oil of the hydraulic pump shared with the swing motor does not join the bottom side of the boom cylinder, it is possible to suppress the boom raising speed, which prevents the boom from rising excessively, and it is also possible to correct it. It becomes unnecessary, and eventually the operation becomes easy.

FIG. 2 is a circuit diagram of a part of the hydraulic circuit of the hydraulic shovel according to the second embodiment of the present invention. In the figure, the same parts as those shown in FIG. 7 '
Is a switching valve corresponding to the switching valve 7 shown in FIG. 1, and a pilot port 7'p is provided on the spring side thereof. Ten
Is a solenoid valve, 11 is a drive power source for the solenoid valve 10, and 12 is a switch. The solenoid valve 10 connects the pilot port 7'p of the switching valve 7'to the tank when it is not energized, and when energized, it is switched to the right position in the drawing to introduce the pilot pressure into the pilot port 7'p.

Next, the operation of this embodiment will be described. First, when the switch 12 is opened, the solenoid valve 10 is at the position shown in the figure, and the pilot pressure is not introduced into the pilot port 7'p of the switching valve 7. Therefore, like the switching valve 7 shown in FIG. 1, the switching valve 7'is maintained at the position shown when the pilot pressure is not introduced from the shuttle valve 8, and is switched to the left position in the drawing when the pilot pressure is introduced. . Therefore, the operation in this case is the same as that of the previous embodiment, and the hydraulic oil of the hydraulic pump 1B is not merged with the boom cylinders 2B ₁ and 2B ₂ during the combined operation.

On the other hand, when the switch 12 is closed, the solenoid valve 10 is switched to the right position in the figure, and the pilot pressure is introduced into the pilot port 7'p of the switching valve 7 '. As a result, the switching valve 7'is not switched even when the pilot pressure from the shuttle valve 8 is introduced, and is held at the position shown in the figure.
Therefore, the operation in this case is the same as the operation of the conventional hydraulic circuit shown in FIG. 3, and the pressure oil of the hydraulic pump 1B is divided into the swing motor 2M and the boom cylinders 2B ₁ and 2B ₂ during the combined operation. The divided pressure oil and the pressure oil of the hydraulic pump 1A join and are supplied to the boom cylinders 2B ₁ and 2B ₂ .

As described above, in this embodiment, the operator of the hydraulic shovel operates the switch to select whether or not to supply the boom cylinder with the pressure oil on the side shared with the swing motor during the combined operation. Therefore, a work suitable for this can be performed under any work condition.

In the above description of the embodiment, the configuration using two boom cylinders has been described as an example, but it goes without saying that the number of boom cylinders may be one. Also, the hydraulic pump is 2
The invention is not limited to one, and the present invention can be applied to a configuration in which other hydraulic pumps are connected in parallel to the illustrated hydraulic pumps.

[Effect of device]

As described above, according to the first aspect of the present invention, the switching prevention means is provided to prevent the pressure oil of the hydraulic pump shared with the swing motor from being supplied to the boom cylinder during the combined operation. Sufficient acceleration can be given to the motor, the swivel of the swivel motor can be sped up to improve work efficiency, and the boom can be prevented from rising excessively. The operation can be facilitated.

Further, in the second aspect of the present invention, it is possible to select whether the switching prevention means is in the operating state or the non-operating state by the selection means, and thus it is possible to perform the work suitable for the working condition. it can.

[Brief description of drawings]

1 and 2 are respectively the first and second parts of the present invention.
FIG. 3 is a partial circuit diagram of the hydraulic circuit of the hydraulic shovel according to the embodiment of the present invention, and FIG. 3 is a partial circuit diagram of the hydraulic circuit of the conventional hydraulic shovel. 1A, 1B …… hydraulic pump, 1C …… pilot pump, 2B ₁ , 2
B ₂ ...... Boom cylinder, 2M ...... Swing motor, 3B ₁ , 3B ₂ , 3M
...... Direction switching valve, 4B, 4M ...... Pilot valve, 7,7 '...... Switching valve, 8 ...... Shear valve, 10 ...... Solenoid valve, 12 ...... Switch.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuichi Ichiyama 650 Jinritsucho, Tsuchiura City, Ibaraki Prefecture Tsuchiura Plant, Hitachi Construction Machinery Co., Ltd. (56) Reference JP-A-57-146842 (JP, A) JP 57-205636 (JP, A) JP 59-233036 (JP, A) JP 60-78022 (JP, A)

Claims (4)

[Scope of utility model registration request] 1. A swing motor, a boom cylinder, at least one hydraulic pump for supplying pressure oil to each of these hydraulic actuators through parallel pipelines, and at least one for supplying pressure oil to the boom cylinder through one pipeline. Two other hydraulic pumps, a first directional switching valve that intervenes in each of the parallel pipelines and drives and controls the swing motor, a second directional switching valve that drives and controls the boom cylinder, and the one pipeline. Third, which intervenes in and drives the boom cylinder
Hydraulic shunt equipped with a directional control valve, a turning pilot valve for operating the first directional control valve, and a boom pilot valve for operating the second directional control valve and the third directional control valve. The hydraulic circuit of the hydraulic shovel, wherein the hydraulic circuit includes a switching prevention means for preventing the switching of the second directional control valve when the turning pilot valve is operated. 2. The switching prevention means according to claim 1, wherein the switching prevention means is interposed between the boom pilot valve and the directional switching valve of the first boom cylinder, and Hydraulic circuit of hydraulic shovel, which is a switching valve that can be switched by pilot pressure of 3. A hydraulic circuit for a hydraulic shovel according to claim 1, further comprising selection means for selecting whether the switching prevention means is operated or not. 4. The switching prevention means according to claim 3, wherein the switching prevention means is interposed between the boom pilot valve and the direction switching valve of the first boom cylinder, and the pilot from the turning pilot valve is provided. A hydraulic circuit for a hydraulic shovel, which is a switching valve that is switched by pressure, and wherein the selecting means is an electromagnetic valve that selectively locks and unlocks the switching valve.