JP2517476Y2 - Excavator sealing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an excavator that excavates and propels under high-pressure ground, such as in tunnel construction, and maintains the sealability between the rotary cutter and the machine casing. Regarding the device.

[Prior Art] Conventionally, as a sealing device of this type, for example, the actual opening 63
-56793 publication. This sealing device has a rotary cutter attached to the front end of the excavator body,
This rotary cutter is rotated to move forward while excavating.
A plurality of annular seal members having the same shape are mounted in parallel at equal intervals in an annular gap provided between the casing of the machine body and the outer circumference of the rotary cutter. Between these seal members is a pressure chamber to which the lubricant is supplied in proportion to the muddy water pressure. The lubricant is gradually reduced in pressure and supplied from the front pressure chamber facing the excavation surface toward the rear inner pressure chamber. The lubricant in the front pressure chamber in the muddy state is on the high pressure side. By discharging the lubricant supplied to each pressure chamber to the outside, it is a structure that prevents the intrusion of muddy water into the inside of the body casing and secures a required sealing property.

[Problems to be Solved by the Invention] By the way, in the case of the sealing device disclosed in this publication, the lubricant is gradually reduced in pressure from the pressure chamber on the front side facing the excavation surface toward the pressure chamber on the rear side and supplied. Because of the structure, it has the following problems. That is, when the front seal member facing the cutting surface and subjected to high-pressure muddy water is damaged or destroyed due to deterioration of durability, the differential pressure between the rear seal member and the rear seal member becomes large. The load acting on the seal member is increased and the service life is shortened, and the service life of the third stage and the fourth stage is reduced proportionally.

Further, the outer peripheral surface of the rotary cutter is heavily worn due to the following factors. That is, a very hard foreign substance such as silica sand intervenes between the lip portion of the seal member and scrapes the surface of the rotary cutter, and the heat generated by sliding contact with the lip portion of the seal member causes corrosion. Acceleration causes chipping on the surface. Further, a large pressing force is applied by the lip portion, and the outer peripheral surface of the rotary cutter is depressed.

Further, since a large amount of lubricant is required to be supplied to the pressure chamber between the adjacent seal members, and since each seal member has a structure having two or more lip portions, the dimension in the axial direction increases, There are many problems such as a large space for accommodating nine seal members and an unnecessarily large size of the device.

An object of the present invention is to provide a sealing device for an excavator that solves these problems.

[Means for Solving the Problems] A sealing device for an excavator according to the present invention is provided between a casing of a machine body and an outer peripheral surface of a rotary cutter, and has a plurality of sealing members facing from the front side to the rear side. A plurality of sealing members are provided in which pressure lubricant for sealing is supplied to the pressure chambers arranged and arranged between the respective sealing members while gradually reducing the pressure from the front side facing the excavation surface to the rear side. A labyrinth seal structure is provided in front of the first stage of the above, and fresh water having a pressure higher than the muddy water pressure is injected into the labyrinth seal structure to prevent the muddy water from entering the body casing.

Further, in the present invention, the labyrinth seal structure portion may have a structure in which a plurality of labyrinth seal members formed in an annular shape are arranged in parallel in the axial direction.

In addition, the present invention provides one of the labyrinth seal members between the fresh water inlet provided in the labyrinth seal structure portion and the first-stage seal member so that the fresh water can be supplied to the first-stage seal member. When the lubricant pressure on the back surface of the first-stage seal member drops below a predetermined pressure, the labyrinth seal member receives the pressure and the inner diameter lip contacts the outer peripheral surface of the rotary cutter to prevent backflow of fresh water. Can also be configured to block.

[Operation] By injecting fresh water having a pressure higher than the muddy water pressure into the labyrinth seal structure, it is possible to prevent the muddy water from entering the airframe casing.

Further, by interposing an annular labyrinth seal member between the fresh water inlet and the first-stage seal member in the labyrinth seal structure, the invasion of fresh water into the first-stage seal member is prevented. Further, when the lubricant pressure applied to the back surface of the first seal member falls below a predetermined pressure, the labyrinth seal member receives the pressure, and the inner diameter lip portion comes into contact with the outer peripheral surface of the rotary cutter to prevent the reverse flow of fresh water.

[Embodiment] An embodiment of a sealing device for an excavator according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic view of a part of the front side of the excavator. That is,
A rotary cutter 11 is rotatably supported inside the body casing 10, and rotary excavation is performed with the head portion 11a of the rotary cutter 11 facing the face excavation surface (left side in the drawing). Three annular seal members 20, 21, and 22 are interposed between the outer peripheral surfaces of the head portion 11a and the boss portion 11b of the rotary cutter 11 and the machine casing 10 at equal intervals in the axial direction.

FIG. 2 is an enlarged cross-sectional view of these three seal members 20 to 22 and one annular labyrinth seal member 23 arranged on the side facing the excavation surface further forward of the frontmost seal member 20. Rotating cutter that is the body casing 10 and rotating shaft
There is a gap C between the outer peripheral surface of the groove 11. This gap C
The labyrinth seal member 23 has a labyrinth seal structure portion 30 in front of the excavation surface. The labyrinth seal member 23 has a first pressure chamber 31 in which pressurized grease (lubricant) as a sealing material and fresh water are turbid. Are formed. However, in the example,
Although the first pressure chamber 31 is shown as being formed in a labyrinthine passage, a structure having the same shape as the above-mentioned annular labyrinth seal member 23 arranged in parallel in the axial direction is shown instead of this labyrinth structure. It is possible. From this meaning, it can be understood that the labyrinth seal structure portion 30 includes the labyrinth seal member 23. The gap between the labyrinth seal member 23 and the first-stage seal member 20 will be referred to as a second pressure chamber 32 to which only pressurized grease is supplied, and hereinafter the first-stage seal member 20.
The gap between the second stage seal member 21 and the second stage seal member 21 is a third pressure chamber 33 to which pressurized grease is supplied, and the gap between the second stage seal member 22 and the third stage seal member 33 is also pressurized grease. It is the supplied fourth pressure chamber 34. A fresh water injection pipe 41 for supplying fresh water to the first pressure chamber 31 is provided on the machine casing 10 side, and a supply pipe 42 for supplying pressurized grease to the third pressure chamber 33 is also provided on the machine casing 10 side. A sealing pressure tube 43 for sealing the pressurized grease is introduced into the fourth pressure chamber 34. Next, an operation mode and an action of the sealing device of the embodiment having the above configuration will be described.

The head portion 11a of the rotary cutter 11 is made to face the face excavation surface, and the rotary cutter 11 is rotationally driven to start excavation. From the clean water injection pipe 41, clean water is labyrinth seal structure 30
Is injected into the first pressure chamber 31. The injection pressure at this time is P ₁ k
It is gf / cm ² . Grease pressure in the second pressure chamber 32 P ₂ kgf / cm ²
Since P ₂ > P ₁ , clear water does not penetrate into the minute gap 23b,
It is discharged outside. The mud pressure P ₃ kgf / cm ² at the labyrinth seal structure portion 30 is lower than the fresh water injection pressure P ₁ kgf / cm ² , and P ₁ >
Since it is P ₃ , the clear water pushes away the muddy water, and this clear water flows out to the muddy water side outside the aircraft.

Next, pressurized grease is supplied from the supply pipe 42 to the third pressure chamber 33 at a supply pressure P ₄ kgf / cm ² . The third pressure chamber 33 is filled with the pressurizing grease, expands the lip portion 20a of the first stage seal member 20, and supplies the pressurizing grease to the second pressure chamber 32 between the labyrinth seal member 23. The lip 23a of the labyrinth seal member 23 and the outer peripheral surface of the rotary cutter 11 have a small gap 2
Since 3b is held, the pressurized grease supplied to the second pressure chamber 32 is discharged to the first pressure chamber 31 on the labyrinth seal structure 30 side. This prevents muddy water and fresh water from entering the second pressure chamber 32. Even when the pressure in the second pressure chamber 32 is reduced due to some accident, the pressure receiving surface including the lip portion 23a of the labyrinth seal member 23 faces the fresh water supply side, so that the lip portion 23a is the outer periphery of the rotary cutter 11. It is possible to prevent the fresh water from entering the second pressure chamber 32 by coming into contact with the surface and eliminating the minute gap 23b. Further, by increasing the amount of water injected from the fresh water injection pipe 41 into the first pressure chamber 31, the amount of pressurized grease supplied from the supply pipe 42 to the third pressure chamber 33 can be greatly reduced. it can.

Here, with respect to pressure grease supplied to the third pressure chamber 33 at a pressure P ₄ kgf / cm ^2, in the fourth pressure chamber 34 of the next, the pressure P _4/2 supplied from inclusion pipe 43 pressurized Seal with pressure grease. In this case, pressure force of the pressure grease in the second stage seal member 21 and the third-stage seal member 22 forming a fourth pressure chamber 34 is a P _4/2, pressure force of the sealing member 20 of the first stage Is almost zero, and the pressure received by the labyrinth seal member 23 is usually 0 kgf / cm ² because it is non-contact. A lubricant such as oil may be used instead of grease.

On the other hand, during excavation work, hard foreign matter such as silica sand may invade the front labyrinth seal structure portion 30 and the periphery of the labyrinth seal member 23, but such foreign matter may enter due to the grease discharged from the minute gap 23b. Is completely shut off. Therefore, there is almost no fear of wear on the outer peripheral surface of the rotary cutter 11. Further, the sealing property against the fresh water injected from the fresh water injection pipe 41 is a labyrinth seal member.
23 plays the role, and since the pressurized grease is continuously supplied from the supply pipe 42 in the third pressure chamber 33 and exceeds the seal member 20 of the first stage, the pressurized grease of the first stage is used. The invasion of fresh water into the lip portion 20a of the seal member 20 is prevented.

Each lip portion 21 of the second to third stage sealing members 21, 22
With respect to the abrasion of the outer peripheral surface of the rotary cutter 11 by a and 22a, since the influence of the pressing force by the lip portions 21a and 22a is evenly distributed, the shaft abrasion on the rotary cutter 11 side hardly poses a problem. In addition, the lip portion 20a of the seal member 20
The generated heat due to the sliding contact between the rotary cutter 11 and the outer peripheral surface of the rotary cutter 11 is suppressed to a low level, and corrosion on the rotary cutter 11 side is not promoted.

Further, the first to third stage seal members 20 to 22 only have a single lip portion 20a to 22a, and the axial length is minimized even if the labyrinth seal member 23 side is included. You can For example, even in the case of an actual machine, the shaft length can be suppressed to about 300 mm. On the other hand, in the case of the sealing device circulated to the rear, since the nine sealing members each have two or more lip portions, the axial length is at least 500 mm or more and is large. Expected to become. Therefore, in the case of the present invention, an increase in the size of the entire device can be suppressed.

FIG. 3 is another structural example of the labyrinth seal structure portion 30 in the embodiment shown in FIG. The labyrinth seal structure portion 50 has a structure that is replaceable with respect to the body casing 10. That is, a pair of labyrinth structures 51 facing each other,
52, and these are bolts 55-58 by pressing members 53, 54.
Is fastened and fixed to the body casing 10. In the case of the illustrated example, the entire labyrinth seal structure 50 is the rotary cutter 11.
Although the structure is arranged on the outer peripheral diameter side, the structure may be arranged on the inner peripheral diameter side of the rotary cutter 11 as shown in FIG.

[Effects of the Invention] As described above, in the sealing device for an excavator according to the present invention, a labyrinth seal structure portion is provided in front of the first stage of the plurality of sealing members, and fresh water having a pressure higher than the mud pressure is provided there. Since the structure is for injecting, it is possible to prevent muddy water from entering the inside of the airframe casing and ensure the required sealing performance. Also,
By increasing the injection amount of fresh water, the supply of pressurized grease can be greatly reduced compared to the conventional structure. In addition, by balancing the injection pressure of fresh water and the supply pressure of pressurized grease, the abrasion that the outer peripheral surface of the rotary cutter receives due to the plurality of seal members is reduced. Furthermore, the dimension in which the plurality of seal members including the labyrinth seal structure portion are accommodated in the axial length direction can be minimized, and the overall size of the device can be suppressed.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of a front part of an excavator to which a sealing device according to an embodiment of the present invention is applied, FIG. 2 is a piping layout diagram of the sealing device according to the embodiment, and FIG. 3 is a labyrinth seal structure. The side sectional drawing of other examples which made a part exchangeable is shown. [Explanation of symbols] 10 …… Machine casing 11 …… Rotating cutter 20 ～ 22 …… Seal member 20a ～ 22a …… Lip part 23 …… Labyrinth seal member 23b …… Micro gap 30 …… Labyrinth seal structure part 31 ～ 34 ...... First to fourth pressure chambers 41 to ...... Fresh water injection pipes 42, 43 ...... Pressurizing grease (lubricant) supply pipes 51, 52 ...... Labyrinth structure 53, 54 ...... Pressing member

Claims (3)

(57) [Scope of utility model registration request] 1. A pressure chamber, which is interposed between a body casing and an outer peripheral surface of a rotary cutter, in which a plurality of seal members are arranged from a front side to a rear side facing an excavation surface and which is provided between the seal members. In a sealing device in which a pressurized lubricant for sealing is gradually reduced in pressure from the front side facing the excavation surface to the rear side, a labyrinth seal structure portion is provided in front of the first stage of the plurality of sealing members, A sealing device configured to inject muddy water having a pressure higher than the muddy water pressure into the labyrinth seal structure portion to prevent the muddy water from entering the airframe casing. 2. The seal device according to claim 1, wherein the labyrinth seal structure portion is configured by arranging a plurality of annular labyrinth seal members in parallel in the axial direction. 3. A labyrinth seal member is interposed between a fresh water inlet provided in a labyrinth seal structure and a first-stage seal member to inject fresh water into the first-stage seal member. In addition, the labyrinth seal member receives the pressure when the lubricant pressure applied to the back surface of the first-stage seal member falls below a predetermined pressure, and the inner diameter lip contacts the outer peripheral surface of the rotary cutter to prevent the reverse flow of fresh water. The sealing device according to claim 1, wherein the sealing device is configured to block.