JPH07315759A - Hydraulic grab bucket - Google Patents

Abstract

PURPOSE:To provide a hydraulic grab bucket capable of safely performing repair and inspection inside an oil tank of large capacity. CONSTITUTION:In a hydraulic grab bucket, a water-tightly sealed chamber 30 is provided in a center frame 20, to provide an oil tank 41 storing operating oil for driving a hydraulic cylinder and an air chamber 47 communicating with the oil tank in this water-tightly sealed chamber 30, and since the constitution is provided so that the air chamber 47 and the oil tank can be interrupted by a valve device, repair and inspection in the oil tank can be safely performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil tank for a hydraulic grab bucket equipped with a hydraulic device for opening and closing a pair of bucket shells that are pivotally supported by a center frame.

[0002]

2. Description of the Related Art Conventionally, in a hydraulic grab bucket having a hydraulic pressure generator inside the bucket, an oil tank for storing hydraulic oil is essential. In this oil tank, since the oil surface changes according to the amount of oil used, an air reservoir is formed.

[0003]

However, in such a conventional drain structure for a hydraulic grab bucket, if the size of the bucket becomes large, the amount of oil used in the hydraulic cylinder becomes enormous, and the capacity of the oil tank also becomes enormous. For example, 300
In a ton-grade hydraulic grab bucket, the amount of oil used is about 20,000 liters. If hydraulic oil is sent from this large amount of oil to the hydraulic cylinder, the oil level in the oil tank will drop. In this state, if the hydraulic grab bucket tilts, the pump may suck air.

Further, it has been proposed that an air chamber is separately provided so that the pump does not suck air when the hydraulic oil is used. However, in the case where a separate air chamber is provided, the oil level is constantly rising during repair and inspection,
There was the drawback that oil would blow out when the lid was opened.

In view of such a conventional hydraulic grab bucket, an object of the present invention is to prevent the pump from sucking air even if the hydraulic grab bucket is tilted, and to safely perform repair and inspection in the oil tank. Intended to serve buckets.

[0006]

In order to achieve the above object, the gist of the present invention is to provide a pair of bucket shells supported by a center frame suspended by wires or the like with a horizontal shaft so as to be openable and closable. In a hydraulic grab bucket including a hydraulic cylinder that drives the bucket shell to open and close, a watertight closed chamber is provided in the center frame, a hydraulic device that generates hydraulic pressure to be sent to the hydraulic cylinder in the watertight closed chamber, and the generated hydraulic pressure. And a control mechanism for controlling the drive of the hydraulic cylinder, and an oil tank for storing hydraulic oil for driving the hydraulic cylinder are provided, and an air chamber communicating with the oil tank is provided, and the air chamber and the oil tank are provided. It is configured such that and can be shut off by a valve device.

The air chamber is arranged above the oil tank. Further, the air chamber is provided with a pipe for pumping oil from the oil tank. Further, the pipe for pumping oil communicates with the oil tank via the switching valve and the hydraulic device.

[0008]

Since the hydraulic grab bucket according to the present invention is provided with another air chamber in addition to the oil tank, the pump does not suck air even if the hydraulic grab bucket equipped with a large oil tank is tilted. The hydraulic oil can be stored in the air chamber when the oil tank is inspected or repaired, so you can work safely.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. 1 is an overall front view of a hydraulic grab bucket according to an embodiment of the present invention, FIG. 2 is a partially cutaway front view of a hydraulic grab bucket according to an embodiment of the present invention, and FIG. It is a principal part expanded sectional view which shows the air chamber of a center frame.

As shown in FIG. 1, the hydraulic grab bucket G is suspended by a suspension fitting 1 which is connected to a wire 9 from a crane boom. Further, the bucket body 10 is
A center frame 20 having a watertight closed chamber 30 therein and accommodating a hydraulic device 40, a pair of bucket shells 50 rotatably supported by the center frame 20, and a top shell of each bucket shell 50 are attached by being attached. And a hydraulic cylinder 60 for opening and closing the bucket shell 50.

As shown in FIG. 2, the center frame 20 is made of a rigid steel structure, and the wire 9 is provided above it.
A shell mounting portion 23 having a mounting metal fitting 21 for mounting the suspension metal fitting 1 hung on the base, and a pivot shaft 22 for pivotally mounting the bucket shell 50 is provided at four corners of the hem. The hydraulic device 40 is installed in the center of the frame.
A watertight closed chamber 30 is formed to store the.

The watertight closed chamber 30 has a welded structure on the four circumferences and the bottom, and is appropriately reinforced on the outside so as to withstand high water pressure, but only the upper part can be opened for periodic inspection. The upper lid 31 is provided with a watertight means by a packing 32. Further, the lower half of the watertight closed chamber 30 constitutes the oil tank 41 of the hydraulic device 40 as it is, and the oil tank 41 and the upper space portion are partitioned by being sealed by the oil tank upper plate 42 and the oil tank packing 43.

The bottom of the oil tank 41 is funnel-shaped toward the center, and a drain reservoir 46 is formed at the lowermost end. In addition, the oil tank upper plate 42 that divides the upper surface of the oil tank 41
An air chamber 47 is formed above. The air chamber 47 is
A communication hole 48 a formed in the bottom plate 48 communicates with the oil tank 41.

As shown in FIG. 3, a valve seat 49 is formed around the communication hole 48a, and the valve body 70 serves as the valve seat 4.
It is arranged so as to be able to abut and retract. The valve body 70 is connected to the support shaft 72 by a sphere 71, and the support shaft 7
A screw 72a is formed on the upper end portion of 2. Screw 72
The a is screwed into a female screw 73 provided on the upper portion of the air chamber 47. Therefore, by rotating the nut portion 72b provided on the head of the support shaft 72, the valve body 70 can be separated from or brought into contact with the valve seat 49. Further, the air chamber 47 is connected to the hydraulic device 40 by a pipe 74.

The electric pump 45 is driven by a motor 44 and supplies hydraulic pressure to each hydraulic cylinder 60. In the present embodiment, the electric pump 45 is of a piston type that generates high pressure and force.

Next, the air chamber 47 of the hydraulic grab bucket constructed as described above will be described. When the hydraulic grab bucket is used for dredging work or the like, the valve body 70 of the air chamber 47 is open and the air chamber 47 is used as an air reservoir of the oil tank 41.

That is, it is desirable that the oil level of the oil tank 41 is as high as possible in order to solve the problem that the pump 45 sucks air when the hydraulic grab bucket is tilted. However, if the amount of air in the oil tank 41 is small, the inside of the oil tank 41 becomes negative pressure when the pump is operated to send the oil,
Stable hydraulic cylinder operation becomes difficult. Therefore,
An air chamber 47 is arranged above the oil tank upper plate 42 to reduce the fluctuation of the oil level due to the inclination of the hydraulic grab bucket, and
The inside of the oil tank 41 is prevented from becoming negative pressure.

If the oil level in the oil tank 41 is high, there is a risk that oil will blow out when the oil tank is opened for repair and inspection. Therefore, when repairing or inspecting, the valve body 70 should be attached to the valve seat 49.
And the communication hole 48a is closed. At this time, the air chamber 4
Since the upper lid 47a of 7 is opened, when oil is supplied, it communicates with the atmosphere from here. After closing the communication hole 48a, the oil from the hydraulic device 40 is accumulated in the air chamber 47 through the pipe 74 by the switching valve 80. As a result, the oil level in the oil tank 41 is lowered to facilitate repairs and the like.

[0019]

As described above, the present invention comprises a pair of bucket shells supported by a center frame suspended by a wire or the like so as to be openable and closable with a horizontal shaft, and a hydraulic cylinder for driving the bucket shells to open and close. In this hydraulic grab bucket, a watertight closed chamber is provided in the center frame, a hydraulic device for generating hydraulic pressure to be sent to the hydraulic cylinder in the watertight closed chamber, and a control mechanism for controlling the drive of the hydraulic cylinder by the generated hydraulic pressure. And an oil tank for storing hydraulic oil for driving the hydraulic cylinder, an air chamber communicating with the oil tank, and the air chamber and the oil tank can be shut off by a valve device. Even if the large oil tank is tilted, there is no risk that the hydraulic device will draw in air. In addition, since oil can be temporarily stored in the air chamber during repair and inspection, it is possible to work safely after lowering the oil level.

[Brief description of drawings]

FIG. 1 is an overall front view of a hydraulic grab bucket according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a center frame of a hydraulic grab bucket according to an embodiment of the present invention.

FIG. 3 is an enlarged sectional view of an essential part showing an air chamber of the center frame.

[Explanation of symbols]

 G Hydraulic grab bucket 9 Wire 10 Bucket body 20 Center frame 21 Mounting bracket 22 Axis 23 Shell mounting part 30 Watertight closed chamber 31 Upper lid 32 Packing 40 Hydraulic device 41 Oil tank 42 Oil tank upper plate 43 Oil tank packing 46 Drain reservoir 47 Air chamber 48 Bottom plate 48a Communication hole 49 Valve seat 50 Bucket shell 60 Hydraulic cylinder 70 Valve body 71 Sphere 72 Support shaft 72a Screw 72b Nut portion 73 Female screw 74 Piping

Claims (4)

[Claims] 1. A hydraulic grab bucket comprising a pair of bucket shells rotatably supported by a center frame suspended by a wire or the like with a horizontal shaft and a hydraulic cylinder for driving the bucket shell to open and close, in the center frame. Is provided with a watertight closed chamber, a hydraulic device for generating a hydraulic pressure to be sent to the hydraulic cylinder in the watertight closed chamber, a control mechanism for controlling the drive of the hydraulic cylinder by the generated hydraulic pressure, and a hydraulic cylinder for driving the hydraulic cylinder. A hydraulic grab bucket, wherein an oil tank for storing hydraulic oil is provided, an air chamber communicating with the oil tank is provided, and the air chamber and the oil tank can be shut off by a valve device. 2. The hydraulic grab bucket according to claim 1, wherein the air chamber is arranged above an oil tank. 3. The hydraulic grab bucket according to claim 1, wherein the air chamber includes a pipe for pumping up oil in the oil tank. 4. The hydraulic grab bucket according to claim 3, wherein the pipe for pumping the oil communicates with an oil tank via a switching valve and a hydraulic device.