JP5394313B2 - Excavation head rotation speed detector for propulsion method - Google Patents

Description

  The present invention relates to an apparatus for detecting the rotational speed of an excavation head in a propulsion method, and more particularly to a technique for detecting the rotational speed of an excavation head using a laser target and a laser beam used for confirming an excavation direction.

Underground pipes used for various purposes, including water and sewage systems, etc., are aging due to changes over time, so it is necessary to replace them with new buried pipes (update pipes) at appropriate times.
In this case, the ground where the existing buried pipe is buried is excavated from the ground surface, the existing buried pipe is excavated, and then a new pipe is suspended and re-embedded, or as shown in FIG. The propulsion method is used in which existing pipes are removed and replaced with renewal pipes while digging in the horizontal direction from the vertical shafts dug in.

In the conventional propulsion method shown in FIG. 6, a start pit 3 is dug on the ground surface G to replace the existing buried pipe 1 with the renewal pipe 2, and a propulsion device 4 is installed at the bottom of the start pit 3. .
Then, the screw conveyor 6 and the excavation head 7 provided at the tip of the screw conveyor 6 are rotationally driven integrally by the drive motor M and the speed reducer 5 of the propulsion unit 4 and are embedded by the excavation bit 8 protruding from the face plate of the excavation head 7. While crushing the tube 1, the surrounding ground is excavated.
The broken pieces of the existing buried pipe 1 and the excavated surrounding soil are transferred rearward by the screw conveyor 6 and the casing 9, taken out to the start pit 3 side, and removed to the ground surface G side.
At the same time, the annular pushing member 11 is propelled forward by the hydraulic cylinder 10 of the propulsion unit 4, the leading conduit 12, the renewal pipe 2, the screw conveyor 6 and the like are moved forward integrally, and the existing buried pipe 1 is changed to the renewal pipe 2. Replace sequentially.

Further, a plurality of direction correcting hydraulic cylinders 14 are provided between the leading conduit 12 and the blade edge portion 13 in preparation for a case where a deviation occurs in the traveling direction of the excavation head 7.
Thus, when these hydraulic cylinders 14 are selectively expanded and contracted to incline the blade edge portion 13 with respect to the tip conduit 12, the inner peripheral surface of the blade edge portion 13 pushes the outer peripheral portion of the excavation head 7 radially inward. Thus, the traveling direction of the excavation head 7 can be corrected.

  Furthermore, by irradiating a laser beam L from the laser theodolite 15 installed in the start pit 4 toward the target 16 suspended in the front conduit 12, the ground can be excavated along the planned line. (For example, refer to Patent Document 1 below).

JP 2008-38485 A

By the way, in the conventional propulsion method described above, it is necessary to detect the rotational speed of the excavation head 7 in order to confirm the excavation state.
At this time, the rotational speed of the excavation head 7 is equal to the rotational speed of the screw conveyor 6.
Therefore, conventionally, a rotary encoder is provided on the rotating shaft of the speed reducer 5 or a proximity sensor is provided in parallel with the gear of the speed reducer 5 to detect the rotational speed of the screw conveyor 6.

However, in order to attach the rotational speed sensor to the propulsion unit 4 that is not provided with this type of rotational speed sensor, complicated modification such as modification of the propulsion unit 4 or change of an electric circuit is required.
Also, if a new rotational speed sensor is attached, trouble may occur.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems of the prior art and provide a new technique for detecting the rotational speed of an excavation head without modifying a propulsion unit used in the propulsion method.

The first invention for solving the above-mentioned problems is
A device for detecting the rotational speed of an excavation head used in the propulsion method,
The propulsion method is
A propulsion unit installed in the start pit, which rotates and drives a screw conveyor provided with an excavation head at the tip thereof and propels an update pipe in the ground excavated by the excavation head;
A laser theodolite installed in the starting pit, which measures a direction in which the excavation head excavates the ground while irradiating a laser beam toward a target propelled integrally with the excavation head, and
The propulsion device has a hollow annular drive member that is rotationally driven by a drive motor and a speed reducer, and holding means that coaxially holds the base end of the screw conveyor inside the drive member.
The holding means is configured to create a state of blocking the laser beam and a state of passing the laser beam,
The target has a first identification unit capable of identifying a state where the laser beam is received and a state where the laser beam is not received, and a state where the laser beam is received from a state where the laser beam is received within a predetermined time. A first measuring unit that measures the number of times of change, and a first computing unit that computes the rotational speed of the screw conveyor based on the number of times measured by the first measuring unit and the predetermined time. An apparatus for detecting the rotational speed of an excavation head in the propulsion method.

That is, when the holding means is configured to allow or block the laser beam, the state of receiving the laser beam and the state of not receiving the light are alternately repeated on the target side as the screw conveyor rotates.
Therefore, in the first invention, the rotational speed of the screw conveyor, and hence the rotational speed of the excavation head, is detected based on the change in the light receiving state of the laser beam at the target.
Thereby, even if the mechanism for detecting the rotational speed of the screw conveyor is not provided in the propulsion device, the rotational speed of the screw conveyor can be detected by installing the novel target of the present invention. Therefore, it is not necessary to modify the propulsion unit, and various troubles associated with the modification of the propulsion unit can be avoided.
Furthermore, by providing a display unit for displaying the rotation speed of the screw conveyor on the target, the rotation speed of the screw conveyor can be known by visually recognizing the target with a laser theodolite.

The second invention for solving the above-mentioned problem is
A device for detecting the rotational speed of an excavation head used in the propulsion method,
The propulsion method is
A propulsion unit installed in the start pit, which rotates and drives a screw conveyor provided with an excavation head at the tip thereof and propels an update pipe in the ground excavated by the excavation head;
A laser theodolite installed in the starting pit, which measures a direction in which the excavation head excavates the ground while irradiating a laser beam toward a target propelled integrally with the excavation head, and
The propulsion device has a hollow annular drive member that is rotationally driven by a drive motor and a speed reducer, and holding means that coaxially holds the base end of the screw conveyor inside the drive member.
The holding means has a reflecting means for reflecting the laser beam to the laser theodolite side,
The laser theodolite has a second identification unit capable of identifying the state of receiving and not receiving the laser beam reflected by the reflecting means, and the state of receiving the laser beam from the state of receiving the laser beam. And a second measurement unit that counts the number of changes within a predetermined time, and a second calculation that calculates the rotational speed of the screw conveyor based on the number of times measured by the second measurement unit and the predetermined time An excavation head rotation speed detection device in a propulsion method characterized by comprising a portion.

Note that the second identification unit, the second measurement unit, and the second calculation unit can be integrated into the laser theodolite, or can be arranged in parallel with the laser theodolite as separate structures.
Moreover, the rotation speed display part which displays the rotation speed which the 2nd calculating part calculated can be integrated in a laser theodolite, or can be arranged in parallel with a laser theodolite as a separate structure.

That is, when the holding means is configured to pass or block the laser beam and a reflecting member that reflects the laser beam to the laser theodolite side is provided on the holding means, the screw conveyor rotates on the laser theodolite side. Accordingly, the state of receiving the laser beam and the state of not receiving the light are alternately repeated.
Therefore, in the second invention, the rotational speed of the screw conveyor, and hence the rotational speed of the excavation head, is detected based on the change in the light receiving state of the laser beam reflected toward the laser theodolite.
Thereby, even if the mechanism for detecting the rotational speed of the screw conveyor is not provided in the propulsion device, the second identification unit, the second measurement unit, and the second calculation unit are arranged on the laser theodolite side. Therefore, it is not necessary to modify the propulsion unit, and various troubles associated with the modification of the propulsion unit can be avoided.

The third invention for solving the above-mentioned problem is
A device for detecting the rotational speed of an excavation head used in the propulsion method,
The propulsion method is
A propulsion unit installed in the start pit, which rotates and drives a screw conveyor provided with an excavation head at the tip thereof and propels an update pipe in the ground excavated by the excavation head;
A self-luminous target propelled together with the drilling head;
Measuring the ground excavation direction of the excavation head by visually recognizing the target, and using a theodolite installed in the start pit,
The propulsion device has a hollow annular drive member that is rotationally driven by a drive motor and a speed reducer, and holding means that coaxially holds the base end of the screw conveyor inside the drive member.
The holding means is configured to create a state that blocks a visual field from the theodolite toward the target and a state that does not block the field of view.
The theodolite measures the number of times the visual field has changed from a bright state to a dark state within a predetermined time, and a third identification unit for identifying a bright state and a dark state when the target is viewed. And a third calculation unit that calculates the rotational speed of the screw conveyor based on the number of times measured by the third measurement unit and the predetermined time. It is the rotational speed detection apparatus of the excavation head in a propulsion construction method.

That is, in the third invention, when the target that emits light by itself is viewed with theodolite, the visual field is blocked by the holding means without being blocked by the holding means, and the visual field is blocked by the holding means. Based on the number of changes within a predetermined time, the rotational speed of the screw conveyor, and hence the rotational speed of the excavation head, is detected.
Thereby, even if the mechanism for detecting the rotational speed of the screw conveyor is not provided in the propulsion device, the third identification unit, the third measurement unit, and the third calculation unit are provided in the theodolite. Therefore, the rotational speed of the screw conveyor can be detected, so that it is not necessary to modify the propulsion unit, and various troubles associated with the modification of the propulsion unit can be avoided.

  A rotation speed display unit that displays the rotation speeds calculated by the first to third calculation units can be provided on the target or theodolite.

  If the light shielding member that rotates integrally with the screw conveyor is provided and the light shielding member shields the laser beam irradiated from the laser theodolite to the target or the light beam that emanates from the target to the theodolite, the propulsion unit can be held. The same effects as the means can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the novel technique which detects reliably the rotational speed of an excavation head can be provided, without modifying the propulsion machine used for a propulsion construction method.

The figure which shows the rotational speed detection apparatus of 1st Embodiment. The figure seen from the arrow A direction in FIG. The figure which shows the structure of the laser target in FIG. 1 typically. The figure which shows the rotational speed detection apparatus of 2nd Embodiment. The figure which shows the rotational speed detection apparatus of 3rd Embodiment. The figure which shows a propulsion construction method.

  Hereinafter, with reference to FIGS. 1-5, each embodiment of the excavation head rotational speed detection apparatus in the propulsion method of this invention is described in detail. In the following description, the same parts are denoted by the same reference numerals, and redundant description is omitted.

First Embodiment First, a rotational speed detection device according to a first embodiment will be described with reference to FIGS.

The rotational speed detection apparatus 100 of the first embodiment detects the rotational speed of the excavation head 7 used in the propulsion method described with reference to FIG.
Specifically, in the propulsion method, the screw conveyor 6 having the excavation head 7 provided at the tip thereof is rotationally driven and the renewal pipe 2 is propelled into the ground excavated by the excavation head 7. A laser installed in the launch pit 3 that measures the direction in which the excavation head 7 excavates the ground by irradiating a laser beam L toward the propulsion device 20 installed and the target 16 that is propelled together with the excavation head 7. Theodolite 15 is used.

At this time, the propulsion device 20 includes a hollow annular drive member 22 rotatably supported by a main body portion via a bearing 21, an annular gear 23 provided on the outer periphery of the drive member 22, and rotating integrally. A pinion gear 24 that meshes with the annular gear 23 and is driven to rotate by a drive motor M is provided.
A holding member 25 extending in the diameter direction is provided inside the hollow annular drive member 22 so that the base end 6a of the screw conveyor 6 is held coaxially with the drive member 22 and rotates integrally. It has become.

As a result, as shown in FIG. 2A, when the holding member 25 extends horizontally, the laser passes through the gap 25a formed between the inner peripheral surface of the drive member 22 and the holding member 25. The target 30 can be visually recognized by the theodolite 15.
On the other hand, as shown in FIG. 2B, when the holding member 25 extends in the vertical direction, the target 30 is hidden behind the holding member 25, so that the target 30 is visually recognized by the laser theodolite 15. I can't.

In other words, as shown in FIG. 2A, when the holding member 25 extends horizontally, the laser beam L irradiated from the laser theodolite 15 toward the target 30 is not blocked by the holding member 25. To reach.
On the other hand, when the holding member 25 extends in the vertical direction as shown in FIG. 2B, the laser beam L emitted from the laser theodolite 15 toward the target 30 is blocked by the holding member 25. The target 30 is not reached.

On the other hand, the target 30 receives the laser beam L emitted from the laser theodolite 15 and has a scale and a geometric pattern for measuring the deviation in the excavation direction on the surface thereof as shown in FIG. It has a translucent light receiving plate 31 which is drawn.
A light guide plate 32 is affixed to the rear surface of the light receiving plate 31, and the laser beam L irradiated from the laser theodolite 15 and transmitted through the light receiving plate 31 is received by an optical sensor such as a photodiode or a phototransistor. It is led to the part 33.

Thus, when the laser beam L emitted from the laser theodolite 15 reaches the light receiving unit 33 via the light receiving plate 31 and the light guide plate 32 without being blocked by the holding member 25 as a light shielding member, the identification unit 34 causes the laser beam L to An ON signal representing the received light is output to the measuring unit 35.
On the other hand, when the laser beam L emitted from the laser theodolite 15 is blocked by the holding member 25 as a light blocking member and does not reach the light receiving plate 31, the identification unit 34 indicates that the laser beam L is not received. Is output to the measurement unit 35.

Based on the ON / OFF signal input from the identification unit 34 and the clock signal input from the timer 36, the measuring unit 35 changes from the state of receiving the laser beam L to the state of not receiving it within a predetermined time. The measured number is measured, and the measured value is output to the calculation unit 37.
The calculation unit 37 calculates the rotational speed of the screw conveyor 6, and thus the excavation head 7, based on the measurement value input from the measurement unit 35 and outputs it to the display control unit 38.
The display control unit 38 controls the operation so that the indicator 39 provided on the upper front surface of the target 30 displays the calculated rotation speed.

  Thereby, the operator who operates the laser theodolite 15 and visually recognizes the target 30 can know the rotation speed of the excavation head 7 by visually recognizing the indicator 39 appearing inside the field of view.

That is, the rotational speed detection apparatus 100 of the first embodiment uses the propulsion unit 4 and the laser theodolite 15 used in the propulsion method as they are, and the conventional target 16 suspended inside the front conduit 12 is a new target 30. It is the structure exchanged for.
Thereby, it is not necessary to modify the propulsion unit 4 in order to detect the rotational speed of the screw conveyor 6, and it is possible to avoid troubles caused by the modification of the propulsion unit 4.

Furthermore, by visually recognizing the target 30 using the laser theodolite 15, the value of the rotational speed of the excavation head 7 displayed on the display unit 39 of the target 30 can be easily confirmed.
Thereby, since it is not necessary to route electrical wiring from the target 30 to the inside of the start pit 3, it is possible to avoid occurrence of unnecessary trouble.

In addition, the measurement part 35 can also be set as the structure which measures the frequency | count of the change in the predetermined time from the state which is not receiving the laser beam L to the state which is light-receiving.
Furthermore, the measuring unit 35 receives the laser beam L based on the ratio of the total time when the laser beam L is received or the total time when the laser beam L is not received and a predetermined time. A configuration for measuring the number of times of change within a predetermined time from the current state to the state of not receiving light, or the number of changes within a predetermined time from the state of not receiving the laser beam L to the state of receiving light You can also

Second Embodiment Next, a rotation speed detection device of a second embodiment will be described with reference to FIG.

The rotational speed detection device 100 according to the first embodiment described above has a structure in which the light receiving unit 33, the identification unit 34, the measurement unit 35, the calculation unit 37, and the like are provided on the target 30.
On the other hand, the rotation speed detection device 200 of the second embodiment includes a rotation speed detection unit 40 having a second light receiving unit, a second identification unit, a second measurement unit, a second calculation unit, and the like. The laser theodolite 15 is arranged side by side.

Specifically, the laser theodolite 15 installed in the start pit 3 is provided with a rotation speed detecting means 40 in parallel.
Further, the holding member 25 of the propulsion device 20 is provided with a reflecting member 41 that reflects the laser beam L irradiated from the laser theodolite 15 toward the target 16 toward the rotation speed detecting means 40.

Thus, as shown in FIG. 2A, when the holding member 25 extends horizontally, the laser beam L emitted from the laser theodolite 15 is between the inner peripheral surface of the driving member 22 and the holding member 25. The target 30 is reached through the gap 25a formed on the surface.
On the other hand, as shown in FIG. 2B, when the holding member 25 extends in the vertical direction, the laser beam L emitted from the laser theodolite 15 is reflected by the reflecting member 41 provided on the holding member 25. Is reflected toward the second light receiving part 42 of the rotational speed detecting means 40.

  Then, the rotational speed detection means 40 of the second embodiment includes the second identification unit, the second measurement unit, the second calculation unit, and the second display control unit of the first embodiment described above. By operating in the same manner as the case, the rotation speed of the screw conveyor 6 is displayed on the second display 43.

That is, the rotational speed detection apparatus 200 of the second embodiment uses the propulsion unit 4 and the laser theodolite 15 used in the propulsion method as they are, and the rotational speed detection means 40 provided in parallel with the laser theodolite 15 and the propulsion unit 4 The rotational speed of the screw conveyor 6 is detected by the reflecting member 41 provided on the holding member 25.
Thereby, in order to detect the rotational speed of the screw conveyor 6, it is not only necessary to remodel the propulsion unit 4 and provide a sensor or the like, but it is possible to avoid troubles caused by the remodeling of the propulsion unit 4.
Moreover, since the structure is simple, it can be easily applied to the propulsion method using the existing propulsion device 4.

Third Embodiment Next, a rotation speed detection device according to a third embodiment will be described with reference to FIG.

The rotation speed detection devices 100 and 200 of the first and second embodiments described above both utilize the laser beam L emitted from the laser theodolite 15 toward the target 16.
On the other hand, the rotational speed detection device 300 of the third embodiment detects the rotational speed of the screw conveyor 6 by visually recognizing the target 51 that emits light by itself using the theodolite 50 provided in the start shaft 4. Is.

  More specifically, the target 51 that emits light itself may be an internal lighting system using an LED as a backlight as disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-64726, which is a prior application of the applicant of the present application. it can.

As a result, as shown in FIG. 2A, when the holding member 25 extends horizontally, the light beam L2 directed from the target 51 that emits light to the theodolite 50 and the inner peripheral surface of the driving member 22 and the holding member 25. The theodolite 50 is reached through a gap 25a formed between them.
Then, the visual field when the target 51 is visually recognized with the theodolite 50 becomes bright.

On the other hand, as shown in FIG. 2B, when the holding member 25 extends in the vertical direction, the light L2 from the target 51 that emits light to the theodolite 50 is blocked by the holding member 25 and the theodolite. 50 is not reached.
Then, the visual field when the target 51 is visually recognized by the theodolite 50 becomes dark.

On the other hand, a half mirror (not shown) is provided inside the theodolite 50, and a third light receiving portion (not shown) is provided below the part of the light beam L2 that reaches the theodolite 50 from the target 51 that emits light. Lead to.
Then, the 3rd identification part which is provided in the interior of the theodolite 50, the 3rd measurement part, the 3rd operation part, and the 3rd display control part are the same as the case of a 1st embodiment mentioned above. It operates to display the rotation speed of the screw conveyor 6 on the third display 52.

That is, the rotational speed detection device 300 of the third embodiment detects the rotational speed of the screw conveyor 6 by the laser theodolite 50 while using the propulsion unit 4 and the target 51 used in the propulsion method as they are.
Thereby, in order to detect the rotational speed of the screw conveyor 6, it is not only necessary to remodel the propulsion unit 4 and provide a sensor or the like, but it is possible to avoid troubles caused by the remodeling of the propulsion unit 4.

As mentioned above, although each embodiment of the excavation target rotational speed detection apparatus in the propulsion method of the present invention was described in detail, it is needless to say that the present invention is not limited to the above-described embodiment, and various modifications are possible. .
For example, in the above-described embodiments, the holding member 25 of the propulsion unit 4 has a structure that blocks the laser beam irradiated from the laser theodolite to the target or the beam extending from the target that emits light to the theodolite.
On the other hand, it goes without saying that the same effect can be obtained by providing another member that rotates integrally with the screw conveyor 6 in the middle of the path of the laser beam or the like.
Moreover, it is needless to say that the propulsion method is not limited to the use of renewing an existing buried pipe as described above, and is intended for various uses.

DESCRIPTION OF SYMBOLS 1 Existing underground pipe 2 Renewal pipe 3 Start pit 4 Propulsion machine 5 Reduction gear 6 Screw conveyor 7 Excavation head 10 Hydraulic cylinder 12 Lead pipe 13 Cutting edge 15 Laser theodolite 16 Target 20 Propulsion machine 22 Drive member 25 Holding member 30 Target 31 Light reception Plate 32 Light guide plate 33 Light receiving unit 34 Identification unit 35 Measurement unit 36 Timer 37 Calculation unit 38 Display control unit 39 Display unit 40 Rotational speed detection means 41 Reflective member 50 Theodolite 51 Target 100 Rotational speed detection apparatus 200 of the first embodiment Rotational speed detection apparatus 300 according to the embodiment Rotational speed detection apparatus according to the third embodiment

Claims (6)

A device for detecting the rotational speed of an excavation head used in the propulsion method,
The propulsion method is
A propulsion unit installed in the start pit, which rotates and drives a screw conveyor provided with an excavation head at the tip thereof and propels an update pipe in the ground excavated by the excavation head;
A laser theodolite installed in the starting pit, which measures a direction in which the excavation head excavates the ground while irradiating a laser beam toward a target propelled integrally with the excavation head, and
The propulsion device has a hollow annular drive member that is rotationally driven by a drive motor and a speed reducer, and holding means that coaxially holds the base end of the screw conveyor inside the drive member.
The holding means is configured to create a state of blocking the laser beam and a state of passing the laser beam,
The target has a first identification unit capable of identifying a state where the laser beam is received and a state where the laser beam is not received, and a state where the laser beam is received from a state where the laser beam is received within a predetermined time. A first measuring unit that measures the number of times of change, and a first computing unit that computes the rotational speed of the screw conveyor based on the number of times measured by the first measuring unit and the predetermined time. An apparatus for detecting the rotational speed of an excavation head in the propulsion method.   2. The excavation method according to claim 1, wherein the target further includes a rotation speed display unit that displays the rotation speed calculated by the first calculation unit toward the laser theodolite. Head rotation speed detection device. A device for detecting the rotational speed of an excavation head used in the propulsion method,
The propulsion method is
A propulsion unit installed in the start pit, which rotates and drives a screw conveyor provided with an excavation head at the tip thereof and propels an update pipe in the ground excavated by the excavation head;
A laser theodolite installed in the starting pit, which measures a direction in which the excavation head excavates the ground while irradiating a laser beam toward a target propelled integrally with the excavation head, and
The propulsion device has a hollow annular drive member that is rotationally driven by a drive motor and a speed reducer, and holding means that coaxially holds the base end of the screw conveyor inside the drive member.
The holding means has a reflecting means for reflecting the laser beam to the laser theodolite side,
The laser theodolite has a second identification unit capable of identifying the state of receiving and not receiving the laser beam reflected by the reflecting means, and the state of receiving the laser beam from the state of receiving the laser beam. And a second measurement unit that counts the number of changes within a predetermined time, and a second calculation that calculates the rotational speed of the screw conveyor based on the number of times measured by the second measurement unit and the predetermined time A rotation speed detecting device for the excavation head in the propulsion method.   The rotation speed detection device for an excavation head in a propulsion method according to claim 3, further comprising a rotation speed display section that displays the rotation speed calculated by the second calculation section. A device for detecting the rotational speed of an excavation head used in the propulsion method,
The propulsion method is
A propulsion unit installed in the start pit, which rotates and drives a screw conveyor provided with an excavation head at the tip thereof and propels an update pipe in the ground excavated by the excavation head;
A self-luminous target propelled together with the drilling head;
Measuring the ground excavation direction of the excavation head by visually recognizing the target, and using a theodolite installed in the start pit,
The propulsion device has a hollow annular drive member that is rotationally driven by a drive motor and a speed reducer, and holding means that coaxially holds the base end of the screw conveyor inside the drive member.
The holding means is configured to create a state that blocks a visual field from the theodolite toward the target and a state that does not block the field of view.
The theodolite measures the number of times the visual field has changed from a bright state to a dark state within a predetermined time, and a third identification unit for identifying a bright state and a dark state when the target is viewed. And a third calculation unit that calculates the rotational speed of the screw conveyor based on the number of times measured by the third measurement unit and the predetermined time. Excavation head rotation speed detection device in the propulsion method.   The said theodolite has further the rotational speed display part which displays the said rotational speed calculated by the said 3rd calculating part, The rotational speed detection apparatus of the excavation head in the propulsion method of Claim 5 characterized by the above-mentioned. .

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