JPH036317B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealing device for a rotary excavator such as a shield excavator, a horizontal hole excavator, or a vertical hole excavator that excavates the ground under high water pressure. This invention relates to a sealing device.

The shield excavator is the first among large-diameter rotary excavators.
This will be explained with reference to the figures. This shield excavator is
A cutter wheel 1 is rotatably supported through a bearing 10 at the front opening of the shield body. A drive motor 12 is fixed to a support bulkhead 13 of the shield body 2, and a turning ring 19 is provided on the cutter wheel 1, and a pinion 11 fixed to the rotating shaft of the drive motor 12 is meshed with the turning ring 19. Between the inner circumferential surface of the large-diameter cylindrical portion 2a of the shield body 2 and the outer circumferential surface of the large-diameter cylindrical portion 1a of the cutter wheel 1, which face each other, and between the outer circumferential surface of the small-diameter cylindrical portion 2b of the shield body 2 and the small-diameter cylinder of the cutter wheel 1. Cutter seals 3a, 4a, 5a, 3b, 4 are provided between the inner peripheral surface of the portion 1b.
b, 5b are interposed. This cutter seal 3a,
4a, 5a, 3b, 4b, and 5b are multi-lip seals with long lip lengths. The drive motor 1
2 and rotate the cutter wheel 1 to excavate the ground. Note that A in the figure represents the inside of the shield body 2, that is, the atmospheric pressure. B indicates the face;
It is under high water pressure and high earth pressure. C indicates a pinion chamber containing the pinion 11 and the like, and D indicates a bearing chamber containing the bearing 10 and the like.

A conventional sealing device for such a large-diameter rotary excavator has a shield main body 2,
Multiple lip type seals 3, 3a, 3b, 4, 4 between 2a, 2b and cutter foils 1, 1a, 1b.
A, 4b, 5, 5a, 5b are interposed in plurality, for example, three. These three multi-lip seals 3,
4 and 5, that is, a first oil reservoir chamber E in the space between the seals 3 and 4, and a second oil reservoir chamber F in the space between the seals 4 and 5,
The feed channels 20 are connected from the grease pump 14 of the pressure fluid feed device, respectively. This conventional sealing device supplies grease from a grease pump 14 to a first oil reservoir chamber E and a second oil reservoir chamber F via a feed path 20, and the first oil reservoir chamber E and second oil reservoir chamber F pressure
This is to prevent excavated earth and sand from entering the shield body 2 by keeping P ₁ and P ₁ the same and almost equal to the water pressure P _W on the face B side. Such conventional sealing devices include multiple lip type seals 3, 4,
5, it has the following advantages.

(1) If the lip length is long, it can better follow the elastic deformation caused by water pressure of large-diameter structures, and the sealing performance is stable. Even if the amount of deflection of the seal changes,
There is little change in seal lip contact pressure and sealing performance remains the same.

(2) Even if the eccentricity between the shield body and the cutter foil increases due to bearing wear, the eccentricity can be tracked well and the sealing performance is stable.

(3) When the seal height is large, the gap between the opposing cylindrical portions of the cutter foil and the shield body is large, which facilitates centering work when fitting and assembling large-diameter heavy structures.

(4) In large-diameter structures, surface hardening treatment (quenching, chrome plating, etc.) of the seal sliding surface is technically difficult, so the surface hardness is low and therefore easily abraded by muddy water. According to
It is easy to prevent the invasion of earth and sand by dividing it into each stage.

However, in conventional sealing devices,
Grease is supplied to the first oil reservoir chamber E and the second oil reservoir chamber F, and the pressure is controlled so that the pressure P ₁ in the first oil reservoir chamber E and the pressure P ₁ in the second oil reservoir chamber F are the same. So,
When the oil pressure _P1 on the back side of the seals 3 and 4 becomes higher than the water pressure Pw on the face B side, grease naturally leaks to the face B side, and the first oil reservoir E between the seals 3 and 4 , and the pressure P ₁ in the second oil reservoir F between _the seals 4 and 5 are both approximately equal to the water pressure P _W on the face B side. Therefore, the pressure difference at the seal 5 closest to the atmospheric pressure P ₀ side of the shield body 2 is P _W −P ₀ =P _W −0=P _W and the water pressure P _W on the face B side is almost equal to this. As a result, the pressure resistance of conventional sealing devices is as follows: Seal 3, 4, 5
In particular, this directly affects the pressure resistance of the seal 5 closest to the atmospheric pressure _P0 side. However, this multi-lip type seal has a long lip length, so it has low pressure resistance and cannot withstand high water pressure. Therefore, the conventional sealing device described above has the disadvantage that it is not suitable for sealing under high water pressure.

Therefore, as a means of improving pressure resistance performance,
There is a plan to increase the rigidity by shortening the lip length and increasing the lip thickness, but with this plan, the above-mentioned advantages are lost, and furthermore, when the cutter foil is eccentric or elastically deformed,
The contact pressure of the seal lip will increase rapidly,
The disadvantage is that the wear rate increases and the seal life is shortened. Seals with iron reinforcing rings may be considered as a way to improve the pressure resistance of roads, but apart from small-diameter seals that are rigid and not difficult to handle and can be handled by hand, large-diameter seals are difficult to handle due to lack of rigidity and are difficult to transport. It has drawbacks such as being difficult to assemble and centering during assembly. Note that rubber seals can be folded and transported. In addition, there is a proposal to improve pressure resistance using a back-up spring, but in this proposal, high water pressure is ultimately transmitted to the gland, and the clearance S between the gland and the seal sliding surface is reduced to prevent the protrusion phenomenon. There is a need to. For this reason, when assembling a large-diameter structure, centering work becomes difficult, and due to eccentricity or elastic deformation of the cutter wheels, the clearance S becomes 0, causing them to come into contact with each other and cause galling.

An object of the present invention is to provide a sealing device for a large-diameter rotary excavator that does not have the above-mentioned drawbacks, can withstand high water pressure, and has a long life.

The present invention forms a plurality of pressure chambers behind a multi-lip seal interposed between an excavator main body and a rotary excavator, and each pressure chamber is connected with a supply path from a pressure fluid supply device. The pressure in the pressure chamber closest to the face among the plurality of pressure chambers is maintained at the same pressure as the water pressure at the face, and the pressure in the next pressure chamber is sequentially reduced to maintain a predetermined pressure. It is characterized by pressure control.

Three examples of the sealing device for a large-diameter rotary excavator according to the present invention will be described below with reference to FIGS. 4 to 6.

FIG. 4 is a partial sectional view showing a first embodiment of the sealing device of the present invention.

In the figure, the same reference numerals as in FIGS. 1 and 2 indicate the same parts.

Therefore, the sealing device of the present invention in this embodiment has a multi-rip seal 22 behind the multi-rip seal 21 interposed between the shield body 2, 2a, 2b and the cutter foil 1, 1a, 1b. 23 is inserted, and two pressure chambers G and H are installed.
form. In other words, the first pressure chamber G has a seal 21 closest to the water pressure P _W on the first face side and a seal 2 in the middle.
2, and the second pressure chamber H is formed between the intermediate seal 22 and the seal 23 closest to the atmospheric pressure P ₀ side of the first shield body 2. The first pressure chamber G and the second pressure chamber H include a first grease pump 14a,
Feeding paths 20a, 2 from the second grease pump 14b
Connect 0b to each.

The sealing device of the present invention in this embodiment has the above configuration, and its operation will be explained below.

Grease is supplied from the first grease pump 14a to the feed path 2
Grease is supplied from the second grease pump 14b to the second pressure chamber H via the supply path 20b, and the pressure in the first pressure chamber G is
P ₂ is maintained at the same pressure as the water pressure P _W on the face B side, and the pressure P ₃ in the second pressure chamber H is set to the pressure in the first pressure chamber G.
2 of the differential pressure between P ₂ and the atmospheric pressure P ₀ on the shield body 2 side
Each pressure is controlled so as to maintain the pressure at one-fold. As a result, the multiple lip type seals 21, 2
It is possible to take advantage of the advantages of 2 and 23 as they are, and also achieve effects such as sufficient resistance to high water pressure.

Here, the sealing performance of the sealing device of the present invention and the conventional sealing device will be explained in more detail by citing specific numbers. The pressure resistance of the multiple lip seals 3, 4, 5, 21, 22, and 23 is assumed to be 5 kg/cm ² .

First, in the conventional sealing device, grease is supplied from the grease pump 14 to the first oil reservoir chamber E and the second oil reservoir chamber F through the feed passages 20, 20, and the first oil reservoir chamber E pressure P ₁ and second oil sump chamber F
The pressure P ₁ is kept the same at 5 Kg/cm ² . As a result, it can withstand only 5 kg/cm ² of water pressure.

On the other hand, in the sealing device of the present invention, the pressure _P3 of the second pressure chamber H to which grease is supplied from the second grease pump 14b is maintained at 5 kg/ ^cm2 ,
On the other hand, the pressure P ₂ in the first pressure chamber G to which grease is supplied from the first grease pump 14a is maintained at 10 kg/cm ² . As a result, it can withstand water pressure of 10Kg/cm ² , twice as much as conventional sealing devices. Moreover,
At the intermediate seal 22, the pressure in the first pressure chamber G
The differential pressure between P ₂ and the pressure P ₃ in the second pressure chamber H is 5Kg/cm ²
In addition, in the seal 23 near the atmospheric pressure P ₀ side of the shield body 2, the pressure in the second pressure chamber H is
The differential pressure between P ₃ and the atmospheric pressure P ₀ of the shield body 2 is 5
Kg/cm ² , which is equal to the differential pressure across the shield 5 of a conventional sealing device. Therefore, in the seal device of the present invention, the contact surface pressure of the seal lip can be made the same as that of the conventional seal device. The advantage of this is that the life of the cutter seal can be extended. It is said that the amount of wear on the seal sliding surface is proportional to the product of the seal lip contact surface pressure and the sliding distance, so the fact that the contact surface pressure is the same as before means that there is no wear despite the high water pressure. It can be assumed that the service life is the same as that of conventional sealing devices. Furthermore, when the water pressure P _W on the face B side is 5 Kg/cm ² , the differential pressure at the seal 5 near the atmospheric pressure P ₀ side of No. 1 shield body 2 of the conventional sealing device is 5 Kg/cm ² which is equal to the water pressure. be. In contrast, the sealing device of the present invention reduces the pressure _P2 in the first pressure chamber E by 5
Since the pressure can be controlled to maintain the pressure P ₃ of the second pressure chamber F at 2.5 kg/cm ² and the pressure P 3 of the second pressure chamber F at 2.5 kg/cm ² , the differential pressure at the intermediate seal 22 is 2.5 kg/cm 2 .
cm ² , the differential pressure at the seal 23 near the atmospheric pressure P ₀ side of the No. 1 shield body 2 is 2.5 Kg/cm ² , and therefore, for the same water pressure, the sealing device of the present invention is half as strong as the conventional sealing device. This can be achieved with a differential pressure of 1. In this way, the differential pressure can be reduced, reducing the amount of wear and extending the life of the seal.

FIG. 5 is a partial sectional view showing a second embodiment of the sealing device of the present invention.

The sealing device of the present invention in this embodiment has a labyrinth type seal for pressure retention made of the same elastic member as the sealing material instead of the seal 23 closest to the atmospheric pressure side among the multiple lip type seals in the first embodiment described above. A seal 24 is interposed, a second pressure chamber H is formed between the labyrinth seal 24 and the intermediate multi-lip seal 22, and an air supply path from the air compressor 15 is connected to the second pressure chamber H. Connect 25.

In this example, the pressure P ₁ in the first pressure chamber G
is maintained at the same pressure as the water pressure P _W on the face B side,
Controlling the pressure P _A in the second pressure chamber H so as to maintain it at one half of the pressure difference between the water pressure P _W (pressure P ₁ in the first pressure chamber G) and the atmospheric pressure P ₀ . Accordingly, the same effects as those of the first embodiment described above can be achieved.

FIG. 6 is a partially sectional view showing a third embodiment of the sealing device of the present invention.

The sealing device of the present invention in this embodiment has the following features in the above-mentioned first embodiment and second embodiment:
A second pressure chamber H is formed in the pinion chamber C and the bearing chamber D by a sealing partition 6 instead of the multiple lip seal 23 and the labyrinth seal 24 on the atmosphere side, and an air compressor 15 is installed in the second pressure chamber H.
Connect the air pipe 25 from the This embodiment can also achieve the same effects as those of the first and second embodiments described above.

In the above-mentioned embodiment, two pressure chambers G and H are formed behind the multi-lip seal 21, but if three or more pressure chambers are formed, the pressure can be increased accordingly. Tolerable enough.

As is clear from the above embodiments, the sealing device of the present invention can achieve the following effects.

1. The pressure resistance of the large-diameter seal at high water pressure has been greatly improved.

2. The seal structure is suitable for any water pressure fluctuation from low water pressure to high water pressure by simply controlling the pressure in the intermediate pressure chamber without changing the seal shape.

3 Even if the water pressure is high, the seal lip contact pressure is
The lip differential pressure can be kept almost constant by adjusting and controlling it, so even if the water pressure fluctuates, the optimal contact pressure can be maintained at all times, reducing the rate of wear on the seal sliding surface and seal lip, and extending the life of the seal. Become.

4 A seal with the same shape as the low pressure seal can be used, so the mold for seal production can be shared.
Economical.

[Brief explanation of the drawing]

Fig. 1 is a sub-sectional view showing a shield excavator in a large-diameter rotary excavator, Fig. 2 is a partial sectional view showing a conventional seal device, and Fig. 3 is a conventional back-up spring type seal. FIG. 2 is a partial cross-sectional view showing the device. 4 to 6 show an embodiment of a sealing device for a large-diameter rotary excavator according to the present invention, FIG. 4 is a partial sectional view showing a first embodiment of the sealing device of the present invention, and FIG. The figure is a partial sectional view showing a second embodiment of the sealing device of the invention, and FIG. 6 is a partial sectional view showing a third embodiment of the sealing device of the invention. 1... cutter foil, 2... shield body,
6...Sealing bulkhead, 11...Pinion, 12...Drive motor, 14, 14a, 14b...Grease pump, 15...Air compressor, 19...Swivel ring, 20, 20a, 20b...Feeding Road, 21,2
2, 23...multi-lip type seal, 24...labyrinth type seal, 25...pressure air path, A...inside the shield body, B...face, C...pinion chamber, D...
...Bearing chamber, G...First pressure chamber, H...Second pressure chamber.

Claims (1)

[Scope of Claims] 1. A rotary excavator is rotatably supported on an excavator body, a multi-lip seal having a long lip length is interposed between the excavator body and the rotary excavator, and the rotary excavator In a large-diameter rotary excavator that excavates the ground by rotating a rotary excavator, a plurality of pressure chambers are formed behind the multi-lip seal between the excavator body and the rotary excavator, and each pressure chamber is filled with pressurized fluid. The feeding paths from the feeding device are connected to each other, and the pressure in the pressure chamber closest to the face among the plurality of pressure chambers is maintained at the same pressure as the water pressure at the face, and the pressure in the next pressure chamber is sequentially reduced. A sealing device for a large-diameter rotary excavator, characterized in that the pressure is controlled so as to maintain the pressure at a predetermined pressure. 2. The sealing device for a large-diameter rotary excavator according to claim 1, wherein the pressure chamber is constituted by a multi-lip seal having a long lip length. 3. The sealing device for a large-diameter rotary excavator according to claim 1, wherein the pressure chamber is constituted by a pressure holding member made of an elastic member. 4. The sealing device for a large-diameter rotary excavator according to claim 1, wherein the pressure chamber is constituted by a sealed partition.