JP2599840B2 - Central shaft sealing device for shield machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield excavator having a center shaft type cutter wheel or an agitator for agitating earth, sand and muddy water, and a partition provided at a front portion of a shield body. The present invention relates to a center shaft sealing device that penetrates and seals between a center shaft to which a cutter wheel or an agitator is attached to prevent intrusion of earth and sand and mud from the face side.

[0002]

2. Description of the Related Art Conventionally, as a central shaft sealing device of a shield machine, an oil chamber is provided between seal stages along the outer peripheral surface of a central shaft, and lubricating oil is supplied to the oil chamber through an oil supply hole. There is one in which the sliding contact surface of the center shaft and the seal is lubricated by being filled with a lubricating oil.

An example of a shield machine having such a central shaft sealing device will be described with reference to FIGS. 3 and 4.

[0004] As shown in FIG. 3, a partition wall 2 for partitioning the in-machine space and the face side is integrally provided at a front portion of the shield main body 1. Is attached. Partition wall 2 and gear case 3
A center shaft 4 penetrating the partition wall 2 is supported by the cutter shaft 5. A cutter wheel 5 for excavating the natural ground E is attached to the front end of the center shaft 4 and a turning gear 6 is attached to the middle part. The swing gear 6 meshes with a drive motor fixed to the gear case 3, for example, a pinion 8 attached to the output shaft of a hydraulic motor 7, and transmits the drive torque to the central shaft 4.
Further, a shield jack 9, a soil discharging screw conveyor 10 and the like are installed behind the partition wall 2.

As shown in FIG. 4, a bearing metal 11 that supports the central shaft 4 is attached to the center of the partition wall 2, and a seal case 12 is fixed by bolts 13.

In the seal case 12, a gland packing 14 for preventing intrusion of earth and sand and mud from the face side,
A gasket 16 for holding the U packing 15 and the gland packing 14 is attached, and a cover 17 is fixed to an end surface of the seal case 12 on the gasket 16 side by bolts 18.

In the above structure, the cutter wheel 5 is rotated by the hydraulic motor 7 to excavate the natural ground E, and the excavated earth and sand 19 is carried out rearward from the chamber formed on the back side of the cutter wheel by the screw conveyor 10. You.

Next, a conventional seal protection mode will be described with reference to FIG. An oil chamber 20 surrounded by the outer peripheral surface of the central shaft 4, the seal case 12, and the U packings 15-1 and 15-2 in the front and rear two stages is opened at one end of an oil supply hole 21 provided through the seal case 12. The other end of the oil supply hole 21 is connected to a discharge side of an oil supply pump 24 via an oil supply pipe 25, and a suction side of the oil supply pump 24 is connected to an oil reservoir 22 via a suction pipe 23. Further, a relief valve 26 is connected between the oil supply pipe 25 and the suction pipe 23. Generally, the lower part of the gear case 3 shown in FIGS. 3 and 4 is used as an oil sump 22 and also serves as an oil sump for lubricating the tooth flanks of the drive gear.

When the oil supply pump 24 is operated, the oil sump 2
The second lubricating oil is supplied to the oil chamber 20 between the seal stages through the oil supply pipe 25 and the oil supply hole 21. Then, when the oil chamber 20 is filled with the lubricating oil, the oil pressure rises, and when the set pressure of the relief valve 26 is exceeded, the relief valve 26 operates to release the pressure oil to the suction pipe 23 side. Now, the set pressure of the relief valve 26 should be lower than the sum of the elastic restoring force of the U packing 15-1 itself in the preceding stage and the pressure of the earth and sand and mud that enter from the face side over the gland packing 14. If set, the amount of the lubricating oil discharged from the oil supply pump 24 is almost all except for the minute leakage used for interfacial lubrication of the sliding contact surfaces of the seals (U packings 15-1 and 15-2). Returns to the oil reservoir 22 through the relief valve 26. At the same time, the lubricating oil is always held at a constant pressure in the oil chamber 20 between the seal stages, and the lubricating oil provides a good sliding contact surface between the U packings 15-1 and 15-2 and the central shaft 4. The lubrication state is maintained.

[0010]

In the above-mentioned prior art, the lubrication of the seal sliding contact surface is performed by the lubricating oil constantly supplied from the oil sump in the gear case to the oil chamber between the seal stages, so that the lubrication system is maintained. It is easy to manage, but the oil pressure drops due to failure of the oil supply pump or oil leak in the oil supply pipe or suction pipe,
Furthermore, there is a lack of consideration for abnormalities such as oil leakage due to damage to the sliding contact surface between the central shaft and the seal.For example, oil leakage has occurred due to failure of the oil supply pump or damage to the oil supply pipe or suction pipe, resulting in a decrease in lubricating oil pressure. Even in this case, since the cutter wheel keeps rotating, heat generation and abnormal wear of the seal due to oil shortage, deformation of the seal due to heat generation, wear of the seal, intrusion of soil particles into mechanical systems such as bearings and gear cases caused by deformation, resulting There is a high possibility that serious damages such as damage to various parts of the mechanical system caused by preventing the continuation of the shield construction will be caused. Then, once the above-described failure occurs, it takes a long time to recover the failure, and there is a possibility that a major failure such as a delay in the construction period of the shield construction may be caused.

Further, if any of the sliding contact surfaces of the seal and the central shaft has a flaw from the beginning, or flaws occur during the excavation, the lubricating oil leaks to the outside through the gap,
Since the amount of leakage exceeds the amount of leakage of lubricating oil due to normal interface lubrication, the lubricating oil in the oil sump is gradually lost, and eventually the oil level in the oil sump becomes lower than the opening of the suction pipe, and the seal sliding contact surface In addition to causing the oil to run out, the seal and the sliding contact surface of the central shaft may be damaged during this period, resulting in a situation in which a great deal of time is required for recovery measures such as seal replacement.

Although the above description has been made with respect to an example of the center shaft sealing device of the cutter wheel, the same problem occurs in the center shaft sealing device of the agitator used for stirring earth and sand or muddy water in the chamber.

A first object of the present invention is to prevent various obstacles caused by a decrease in lubricating oil pressure in a central shaft seal device of a shield machine that constantly supplies lubricating oil to an oil chamber provided between seal stages. Or at a mild stage to avoid significant damage such as delays in the construction of the shield.

A second object of the present invention is to provide a center shaft seal device for a shield machine, which constantly supplies lubricating oil to an oil chamber provided between seal stages, so that either the seal or the center shaft can be brought into sliding contact. An object of the present invention is to catch an oil leak caused by surface damage at a mild stage, to prevent the subsequent damage from advancing, and to avoid serious damage such as a delay in the construction period of a shield work.

[0015]

In order to achieve the above first and second objects, the invention according to claim 1 is connected in the middle of an oil supply pipe for supplying lubricating oil to an oil chamber between seal stages. a pressure detecting means for outputting a hydraulic pressure drop signal when the lubricating oil pressure in the tube drops abnormally, the oil supply pipe oil supply hole near
When it is inserted nearby and the flow rate of lubricating oil in the pipe increases abnormally
Flow rate detecting means for outputting an excessive flow rate signal to the apparatus , and when the oil pressure decrease signal is inputted, and when the oil pressure decrease signal is inputted,
Even if it is not provided, it is provided with a signal processing means for instructing an alarm display or a cutter stop when the excessive flow rate signal is input .

[0016]

[0017]

[Function] The pressure detecting means is connected in the middle of the oil supply pipe, and when the lubricating oil pressure in the pipe is abnormally decreased, that is, the oil pressure is lower than the normal value when the oil supply pump malfunctions or the oil supply pipe or suction pipe is damaged. Sometimes, a hydraulic pressure drop signal is output. Further, the flow rate detecting means is inserted in the vicinity of the oil supply hole of the oil supply pipe, and when the lubricating oil flow rate in the pipe abnormally increases,
That is, an excessive flow rate signal is output when the flow rate becomes larger than a normal flow rate corresponding to a minute leak due to interface lubrication of the seal sliding contact surface.

A low oil pressure signal or an excessive flow rate signal
Either when one is input No., the signal processing means or to direct the cutter or stop command an alarm display, sealing or center mild stage before reaching the oil pressure
It is possible to prevent the sliding contact surface of the shaft from being damaged.

[0019]

[0020]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a view showing a cross section of a seal portion of a first embodiment corresponding to claim 1, and a flow of signals of a lubricating oil pipe and an electric system, and FIG. 2 is a seal of a second embodiment corresponding to claim 2. FIG. 6 is a diagram showing a cross-section of the part and a flow of signals of the lubricating oil pipe and the electric system. The lubricating oil pipe is shown by a solid line, the flow of the electric system signal is shown by a broken line, and the same reference numerals as in FIG.
In FIGS. 1 and 2, two front and rear U-packings 15-1 and 15-15 serving as earth and sand seals are provided in a seal case 12.
-2 is attached, and an oil chamber 20 surrounded by the central shaft 4 having a cutter wheel attached thereto, the seal case 12, and the U packings 15-1 and 15-2 is provided between the seal stages. An oil supply hole 21 that penetrates through the seal case 12 is opened in the oil chamber 20, and the other end of the oil supply hole 21 is connected to the discharge side of an oil supply pump 24 via an oil supply pipe 25 to provide oil supply. The suction side of the pump 24 is connected to the oil reservoir 22 via a suction pipe 23. A relief valve 26 is connected between the oil supply pipe 25 and the suction pipe 23. When the pressure on the oil supply pipe 25 side exceeds the set pressure of the relief valve 26, the pressure oil is returned to the suction pipe 23 side. Therefore, when the oil supply pump 24 is operating normally, the oil chamber 20 between the seal stages is kept filled with the lubricating oil at a specified pressure according to the set pressure of the relief valve 26. The U-packing 15-1 in the front stage is attached to the side opposite to the oil chamber 20 and the U-packing 15-2 in the rear stage is attached to the side close to the oil chamber 20.
This is to prevent dirt and muddy water that has passed over 4 from entering the bearing metal 11 side. Therefore, the pressure of earth and sand or muddy water is usually applied to the open side of the U packing 15-1 in the previous stage, and the U packing itself also has an elastic restoring force to be deformed when it is installed. By setting the set pressure of the relief valve 26 to be lower than the sum of the force and the pressure of the above-mentioned earth and sand or muddy water, there is usually almost no leakage of lubricating oil from the oil chamber 20. Almost all the amount of the lubricating oil discharged from the oil supply pump 24 is leaked by a very small amount of the amount used for the interfacial lubrication of the sliding contact surfaces of the U packings 15-1 and 15-2 and the central shaft 4 and the relief valve 26.
And returns to the suction pipe 23 side, so that the oil chamber 20 is always maintained in a normal state in which the lubricating oil is filled with a constant pressure.

Now, let us assume that the suction pipe 23 or the oil supply pipe 25 is used.
If it is assumed that oil leakage occurs due to a gap in the pipe connection or damage to the pipe, or that the discharge pressure is reduced due to failure of the oil supply pump 24, the lubrication held in the oil chamber 20 is naturally The oil pressure also drops. In the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. 2, a pressure detecting means 27 is connected in the middle of the oil supply pipe 25 in order to cope with this decrease in oil pressure.

The pressure detecting means 27 monitors the lubricating oil pressure in the oil supply pipe 25 and outputs a hydraulic pressure decrease signal when the oil pressure falls below a specified pressure. A pressure switch that produces a signal is used. Alternatively, the pressure sensor may be composed of a pressure sensor that converts pressure into an electric signal and a comparator that compares the output signal with a reference level.

The pressure detecting means 27 is connected to an input side of a signal processing means 28 such as a sequencer, and a cutter drive control circuit 29, a buzzer and an indicator lamp built in a shield control panel are provided on the output side of the signal processing means 28. In addition, an alarm indicator 30 independently installed in the shield driver's seat or incorporated in the operation panel is connected.

When the lubricating oil pressure in the oil supply pipe 25 falls below the specified pressure for some reason, a pressure decrease signal is output from the pressure detection means 27, and the signal processing means 28 causes the oil supply pump 2 to operate.
When the hydraulic pressure drop signal is input despite the fact that 4 is in the operating state, a cutter stop command is issued to the cutter drive control circuit 29 to stop the drive of the cutter wheel, and at the same time, an alarm display is issued to the alarm display 30. Then, the driver is informed of the decrease in hydraulic pressure. This prevents the seal sliding contact surface from running out of oil, and if the cause of low oil pressure is a malfunction of the oil supply pump or oil leak in the piping, it can be easily restored by repairing the pump and piping. is there.

Next, whether any of the sliding contact surfaces of the U packings 15-1 and 15-2 and the center shaft 4 has scratches from the beginning,
Alternatively, assuming that a scratch occurs during excavation, in addition to the small amount of leakage used for normal interface lubrication of the sliding contact surface, the lubricating oil in the oil chamber 20 can be obtained from the gap of the damaged portion of the sliding contact surface. May leak to the outside. If the amount of leakage is such that the oil pressure does not decrease, the oil in the oil reservoir 22 is gradually lost, and when the oil level becomes lower than the opening of the suction pipe 23, the oil pressure decreases for the first time. And the U packings 15-1 and 15
-2 or the sliding contact surface of the central shaft 4 may be damaged, leading to a situation where a large amount of time is required for recovery measures such as replacement of a seal. In the second embodiment shown in FIG. 2, in order to cope with this problem,
A flow rate detecting means 31 is inserted in the vicinity of 1.

The flow rate detecting means 31 monitors the flow rate of the lubricating oil in the oil supply pipe 25 and outputs an excessive flow rate signal to the signal processing means 28 when the flow rate exceeds a specified value. A baffle plate rotatably supported is provided, and when the flow rate (flow velocity) exceeds a specified value, a baffle plate is moved by the dynamic pressure of the fluid to open and close contacts, and a flow rate sensor that generates an electric signal is used. . Further, it may be composed of a flow rate sensor for converting the flow rate into an electric signal and a comparator for comparing and judging the output signal with a reference level. The flow rate detecting means 31 is installed at a position as close as possible to the oil supply hole 21 in order to detect oil leakage caused by damage to the sliding contact surface between the seal and the central shaft separately from oil leakage of the oil supply pipe. In this case, since the flow rate of the lubricating oil to be detected is extremely small in the normal state as described above, the specified value of the flow rate is also a very small value. Therefore, if the normal flow rate is ignored, the flow rate detection means 31 can be simply regarded as a means for determining the presence or absence of flow.

In this embodiment, when the flow rate of the lubricating oil supplied to the oil chamber 20 exceeds the specified value, the flow rate detecting means 31 outputs an excessive flow rate signal before the hydraulic pressure drops. (The signal processing means 28 issues an alarm display command to the alarm display 30 when the excessive flow rate signal is input even if the oil pressure decrease signal is not input, and notifies the driver of the abnormality of the seal portion.
At the same time, it is also possible to instruct the cutter drive control circuit 29 to stop the cutter to stop driving the cutter wheel. Due to the shield work, it is conceivable to stop the cutter wheel immediately after excavating one ring without immediately stopping the cutter wheel. According to the present embodiment, damage to the sliding contact surface between the seal and the central shaft can be detected at a light stage, and thereafter, if the lubricating oil supplied between the seal stages is switched to grease, the seal and the The central shaft can be used as it is to prevent leakage due to the characteristics of the grease itself and prevent intrusion of soil particles. As a result, the progress of damage to the sliding contact surface can be suppressed.

[0029]

As described above, according to the invention of claim 1, the pressure of the lubricating oil supplied between the seal stages and
Always monitor the flow rate to check if the oil pressure has dropped or the flow rate has increased abnormally.
When an addition is detected, an alarm can be displayed and the cutter can be stopped, so that heat and abnormal wear of the seal due to oil depletion, seal deformation due to heat generation, seal wear, dirt intrusion caused by deformation, dirt particles Of abnormal wear of the seal and the central shaft due to intrusion of soil, resulting in infiltration of soil particles into mechanical system parts such as bearings and gear cases.
Damage to each part of the mechanical system due to this can be prevented in advance or at a mild stage. In addition, the seal and the central shaft
Oil leakage caused by damage to the sliding contact surface is
Capture earlier than below to prevent further damage
can do.

[0030]

Thus, recovery is achieved by catching the oil leakage caused by the decrease of the lubricating oil pressure and the damage of the sliding contact surface between the seal and the central shaft at an early stage and preventing the subsequent damage of the seal part and each part of the mechanical system. The construction is facilitated, the time required for the construction is greatly reduced, and there is an effect that serious damage due to delay in the construction period of the shield construction can be avoided.

[Brief description of the drawings]

FIG. 1 is a view showing a cross section of a seal portion and a flow of signals of a lubricating oil pipe and an electric system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a cross section of a seal portion and a flow of signals of a lubricating oil pipe and an electric system according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing an example of a shield machine to which the present invention is applied.

FIG. 4 is a detailed cross-sectional view of a seal portion (A portion in FIG. 3) targeted by the present invention.

FIG. 5 is a diagram showing a cross section of a seal portion and a lubricating oil pipe according to a conventional technique.

[Explanation of symbols]

1 ... Shield body, 2 ... Partition wall, 4 ... Central axis, 5 ... Cutter wheel, 15-1, 15-2 ... U packing (seal),
Reference Signs List 20: oil chamber between seal stages, 21: oil supply hole, 24: oil supply pump, 25: oil supply pipe, 27: pressure detection means, 28: signal processing means, 29: cutter drive control circuit, 30: alarm display, 31 ... Flow detection means.

Claims (1)

(57) [Claims] 1. A shield for sealing between a partition wall provided at a front portion of a shield body and a central shaft penetrating the partition wall and having a cutter wheel or an agitator attached thereto to prevent intrusion of earth and sand and mud from the face side. A center shaft sealing device for an excavator, wherein an oil chamber is provided between seal stages along a center shaft outer peripheral surface, lubricating oil is supplied to the oil chamber through an oil supply hole, and the oil chamber is always filled with lubricating oil. In what
A pressure detecting means, which is connected in the middle of the oil supply pipe for supplying lubricating oil to the oil chamber, outputs a hydraulic pressure decrease signal when the lubricating oil pressure in the pipe is abnormally decreased, and an oil supply hole near the oil supply pipe.
When the lubricating oil flow in the pipe is abnormally increased
Flow rate detecting means for outputting an excessive flow rate signal to the apparatus , and when the oil pressure decrease signal is inputted, and when the oil pressure decrease signal is inputted,
And a signal processing means for instructing an alarm display or instructing a cutter stop when the excessive flow rate signal is input .