JP2000130080A - Oscllating portion supporting construction for small- aperture drive machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supporting construction for oscillating portion capable of effectively utilizing the internal space even for a guiding pipe having a small diameter and of oscillating with a high accuracy. SOLUTION: A guiding pipe 1 has two or more divided outer cylindrical bodies 31, 34, of which, one set of at least a pair of front and rear divided outer cylindrical bodies 31, 32 are coupled and supported in a freely oscillating manner by a plurality of oscillating jacks 36. One end 36a of the oscillating jack 36 is fixed to one 32 of the pair of divided outer cylindrical body 31, 32, and other end 36b of the oscillating jack 36 is spherically supported by the spherical supporting body 38a of the other divided outer cylindrical body 31. Moreover, the connecting portion of the pair of divided outer peripheral cylindrical bodies 31, 32 connected liquid tightly through seal member 35, and the seal member 35 is arranged near on the circular plane containing a plurality of the spherical supporting portion 38a in a state of the oscillating jack expanded by half stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swinging mechanism for a small-diameter thruster, and more particularly to a swinging support structure for a pair of front and rear outer cylinders constituting a swinging portion in a forward conduit of the thruster.

[0002]

2. Description of the Related Art A small-diameter thruster of this type is configured such that a propulsion device installed in a starting shaft and a push plate of the propulsion device press an outer cylinder of a leading pipe or a subsequent buried pipe under the ground by a push plate. It is applied to a wide variety of burial pipe laying works such as improvement of sewer pipes, small-scale sewerage and drainage of agricultural settlements, and underground drainage facilities and distribution lines.

[0003] Generally, excavation by this small-diameter thruster causes linear propulsion from the starting shaft to the reaching shaft.
Conventionally, the direction of excavation may be deviated, and a structure in which the excavation is slightly bent between the outer cylinder that accommodates the leading pipe, particularly, the outer cylinder that accommodates the cutter head, and the succeeding outer cylinder is employed. In the bent structure, for example, the front and rear ends of the direction correcting jack are connected between the rear end of the front body of the leading conductor and the middle body. Then, when the propulsion direction of the leading conduit deviates from the plan line, the jack for correcting the direction is operated to swing the tip excavation portion, the propulsion is continued as it is, and the propulsion plan line for gradually correcting in the swing direction. Judging the tendency to return to the direction, return the direction correcting jack to its original position and stop swinging.

[0004] A general connecting and supporting structure between a front trunk and a middle trunk in a conventional front conduit is shown in FIG.
The front and rear ends of the oscillating jack 6 are spherically supported on the inner and outer trunks 5, respectively, or the base end of the cylinder tube 6a of the oscillating jack 6 is fixed to the inner trunk 5 as shown in FIG. 6b is inserted into a rod insertion hole 7a formed in a support frame portion 7 fixed to the inner wall surface of the front body portion 4, and a nut 8 is screwed into a tip screw portion of the rod.
Is supported. According to the latter support structure, the distal end surface of the piston rod 6b is formed into a spherical surface, and the rod insertion hole 7a is formed to secure a preset swing range of the distal end of the piston rod 6b.
Is set to be larger than the diameter of the piston rod by about 2 mm so that a large clearance is formed between the rod insertion hole 7a and the piston rod 6b.

The swing angle of the front body is determined by the amount of expansion and contraction of a plurality of swing jacks, and the stroke is detected to determine the curvature in the excavation direction. Therefore, a stroke detector, which is a swing amount detecting means, is provided side by side at each of the swing jack installation sites. As the most efficient detector arrangement for detecting the stroke, mounting along the axis of the oscillating jack, in addition to being able to effectively use the installation space,
This is desirable because the amount of expansion and contraction of the swinging jack can be directly detected.

However, in the case of a support structure that supports both ends of the swinging jack spherically, the rear end supporting portion of the swinging jack is rotatably supported. Arranging such cables is also difficult from the structural point of view. Therefore, conventionally, the stroke detector is often provided adjacent to the swinging jack. In this case, it is desirable that the operation of the stroke detector follows the expansion / contraction operation of the rocking jack. For this reason, conventionally, similarly to the rocking jack, both ends of the stroke detector have a spherical support structure.

[0007]

As shown in FIG.
When both ends of the above-mentioned rocking jack are spherically supported, the rocking jack becomes a link, and the whole rocks around both ends as a fulcrum, and is connected to the hydraulic port of the rocking jack with this rocking. In order to give flexibility to the movement of the hose, at the same time, it is necessary to use hoses, because the piping to be swung also requires flexibility for the piping.
It is necessary to attach it with a margin to its length. As a result, the space occupied by the oscillating mechanism becomes large, and this causes more inconvenience particularly in the leading pipe of a small-diameter thruster having a small internal space and a small diameter. On the other hand, since the oscillating jack or the like is disposed in a narrow installation space, the oscillating jack itself must be reduced in size, and therefore, there is a problem that sufficient oscillating power cannot be obtained.

In the case where the swing support structure shown in FIG. 11 is employed, in which the base end of the cylinder tube of the swing jack is fixed to the middle body, and the end of the piston rod is inserted through the through hole and fixed with a nut. However, as described above, there is no need to connect hoses, and the hydraulic pipe can be connected, so the above-mentioned problem is eliminated.However, if the swing width of the leading conduit is to be increased, the piston rod of the swing jack is naturally used. And a large clearance must be provided between the rod insertion hole formed in the cutter head and the rod. Therefore, rattling becomes large at the time of direction correction or curve propulsion, and it is difficult to correct the direction accurately, and a smooth curve is obtained. Propulsion cannot be performed either.

When both ends of the stroke detector are spherically supported, the swing center of the stroke detector is not uniquely determined, and it is difficult to accurately and quickly detect the swing angle of the leading conduit. .

The present invention has been made to solve such a conventional problem. Specifically, a rocking jack or the like can be easily arranged in a narrow space of a small-diameter front conduit, and rattling can be prevented. It is an object of the present invention to provide a swinging portion support structure for a small-diameter thruster capable of correcting the direction accurately with a small amount. Other objects will be clarified by a description of a preferred embodiment of the present invention described later.

[0011]

This object is effectively achieved by the present invention according to claims 1 to 4 as described below. That is, in the invention according to claim 1, the leading conduit has two or more divided outer cylinders, and at least one pair of the front and rear divided outer cylinders is swingably connected and supported by a plurality of swing jacks. A swinging portion supporting structure of the small-diameter propulsion device, wherein one end of the swinging jack is fixed to one of the pair of divided outer cylinders, and the other end of the swinging jack is the other end. It is characterized in that it is spherically supported by the divided outer cylinder.

Since one end of the oscillating jack is fixedly mounted on the other divided outer cylinder, a fixed pipe can be connected to the oscillating jack instead of flexible hoses. It can be housed and installed compactly in the internal space of the front conduit. In addition, since one end of the swinging jack is spherically supported by one of the divided outer cylinders, it is possible to perform accurate swinging with less rattling.

In the invention according to claim 2, claim 1 is
In addition to the configuration of the invention according to the above, further, in a state where the pair of divided outer cylinders are connected in a liquid-tight manner via a seal member, and the plurality of swing jacks extend by a half stroke, a plurality of spherical surfaces are provided. The seal member is arranged near a plane including the support portion.

According to such a configuration, the swing center of the leading pipe is located on the cross section of the leading pipe at the sealing position. For this reason, the displacement of the sealing portion in the radial direction of the leading end of the sealing portion is extremely small even at the time of swinging.

According to a third aspect of the present invention, one end of the swing amount detecting means is spherically supported in a circular plane including the spherical support portion of the swing jack, and the other end of the swing amount detecting means is connected to one of the divided outer cylinders. It stipulates that it is fixed, and this configuration allows it to be compactly housed and installed in the narrow inner space of the front conduit like a swinging jack, and to achieve high accuracy and reliability without excessive deformation A high swing amount can be detected.

According to a fourth aspect of the present invention, in addition to the third aspect of the present invention, it is further provided that the swing amount detecting means is incorporated in the swing jack.
That is, since the swing amount detecting means is integrated with the swing jack and attached, and the expansion and contraction of the swing jack can be detected as it is, the swing jack can be housed and installed more compactly, and the detection accuracy can be increased.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 shows, in a longitudinal section, a part of a leading conduit provided with a swinging portion support structure of the present invention. Although the overall configuration of the front conduit 1 is substantially the same as the conventional one, the support structure of the cutter head 2 and the swinging part 3 is a structure unique to the present invention, and is greatly different from the conventional one. .

In FIG. 1, the leading conduit 1 is housed in a cylindrical shield case 30 having a required length and rotatably supporting a cutter head 20 at the tip. The shield case 30 is, for example, a cutter. Head part 31, swing part 3
2, divided into a pinch portion 33 and a rear end portion 34. A cutter head 20 is rotatably supported by the cutter head section 31. A rotation shaft 21 of the cutter head 20 is accommodated in a screw casing 40 extending rearward along the hollow portion axis of the front conduit 1. And is rotated with the driving rotation of the screw 41.

In the example shown in the figure, the cutter head 31 which is a divided outer cylinder of the cylindrical shield case 30 of the present invention is shown.
A connecting portion between the swinging portion 32 and the swinging portion 32 has a front end portion which is liquid-tightly fitted to a rear end portion of the cutter head portion 31 via a sealing member 35 and a swinging jack 36 therebetween. And are connected and supported so as to be relatively slidable. Therefore, the space between the inner surface of the connection portion of the cutter head 31 and the swinging portion 32 and the screw casing 40 is provided with a plurality of swinging jacks 36 and a swinging amount detecting means at predetermined intervals in the circumferential direction. And a stroke detector 37. A pinch valve 50 is attached to the pinch part 33, and the screw casing 40 from the cutter head 20 to the pinch valve 50 is filled with excavated soil, and while balancing this with the face thickness on the front surface of the cutter, the amount of soil discharged and Controls water retention. The rear end 34 is provided with a laser target for measuring the position of the leading pipe by using a laser beam from the starting shaft, and a buried pipe is sequentially connected and propelled and buried behind the rear end.

FIG. 2 is an internal side view in which a part of a connection structure at a connection portion between the cutter head portion 31 and the swing portion 32 according to the first embodiment of the present invention is partially cut away. In the illustrated example, a donut disk-shaped first support member 38 is fixed to the inner surface of the rear end (the right end in the drawing) of the cutter head portion 31, and a ring is provided on the outer peripheral surface of the first support member 38. A sliding member 31a extending in the rear along the peripheral edge.
On the other hand, a ring-shaped sliding contact member 32a is also provided on the inner surface of the front end (left end in the drawing) of the swinging portion 32 and extends forward along the peripheral edge, and the sliding contact member 32a is connected to the sliding member 31a.
Are slidably and axially slidable along the inner surface of the member through a seal member 35 in a liquid-tight manner. The swing unit 3
A donut disk-shaped second support member 39 is also fixedly provided along the periphery of the rear end of the second support member 39.

The first support member 38 is provided with four spherical support seats 38a at the rear end face thereof with equal phase difference, and the four spherical support seats 38a of one of the second support members 39 A stepped jack end insertion hole 39a that penetrates and supports the bottom portion 36e of the swinging jack 36 is formed at the opposed position. In this embodiment, the swing jack 3 is attached to the spherical support seat 38a.
The piston rod end 6 is rotatably supported in all directions. Therefore, the end of the piston rod 36b forms a spherical portion 36b '.

In such a configuration, the swing center of the leading conduit 1 when swinging is located in a plane connecting the centers of the spherical surfaces of the plurality of spherical support portions. For this reason, the displacement of the spherical support portion in the radial direction of the tube when the swing jack 36 is expanded and contracted is extremely small, and the rattling of the fitting of the spherical portions can be suppressed, and the swing can be performed with high precision. .

A plurality of spherical support positions of the cutter head portion 31 for spherically supporting the front end of the rocking jack 36 when the rocking jack 36 is at the intermediate position between the fully contracted state and the fully extended state, Cutter head 3 which is a cylindrical body
The connection position of the first and the swinging part 32 by the seal member 35 has an important meaning for the present invention. That is, FIG.
As can be understood from FIG. 3 and FIG. 3, in the present invention, the plane formed by the spherical supporting end when the plurality of swinging jacks 36 are extended by a half stroke, and the sealing member 35 at that time are formed. By making the planes that contain them as close as possible, preferably by making both planes completely coincident,
The swing center of the leading conduit 1 is located substantially on the seal section AA. Therefore, as in the case of the spherical support portion of the swinging jack 36, the amount of displacement of the sealing portion of the sliding member 31a in the radial direction at the time of swinging of the leading conduit is extremely small, so that reliable sealing performance can be obtained. Not only small seals can be employed.

The stepped jack end insertion hole 39a formed in the second support member 39 has a first large-diameter portion into which a bottom 36e of the swinging jack 36 is fitted and seated, and the same bottom 36e.
A small-diameter portion that projects rearward from a tube-shaped detector insertion support portion 36f, which will be described later, and a rear end of the swinging jack 36 is fixed to the small-diameter portion via a detector insertion support portion 36f with a nut. It consists of two large diameter parts. Also,
The second support member 39 is formed with through holes 39b, 39c for inserting piping connection portions of the pressure oil input / output ports 36c, 36d of the swing jack 36, which will be described later.

FIG. 4 is an enlarged side view showing the rocking jack 36 partially cut away, and FIG. 5 is a rear view of the jack. The oscillating jack 36 in this embodiment has a cylindrical cylinder tube 36a and a piston rod 36b as shown in FIG. 4, and the bottom side oil chamber and the piston of the oscillating jack 36 are provided on the outer peripheral surface of the cylinder tube 36a. A pressure oil inlet / discharge port 36c communicating with the side oil chamber,
36d is provided with a slight phase shift in the circumferential direction, and a tube-like detector insertion support portion 36f for inserting and supporting the stroke detector 37 projects from the center of the bottom 36e of the cylinder tube 36a. Has been established. On the other hand, a detection end insertion fixing hole 36g for inserting and fixing the detection end 27b of the stroke detector 37 is formed along the axis at the base end center of the piston rod 36b. Further, a screw is cut on the outer peripheral surface of the tube-shaped detector insertion support portion 36f.

Now, the cutter head 3 of the shield case 30 is moved by the swinging jack 36 having the above-described structure.
In order to connect and support the swinging portion 1 and the swinging portion 32, the spherical portion 36 b ′ of the piston rod end of the swinging jack 36 is connected to the spherical surface of the first support member 38 fixed to the rear end peripheral surface of the cutter head portion 31. It is held by the support seat 38a. Therefore, the spherical support seat 38a has a split structure. On the other hand, the bottom portion 36e of the cylinder tube 36a of the swing jack 36
Is seated on the first large-diameter portion of the stepped jack end insertion hole 39a formed in the second support member 39 fixed to the rear end of the swinging portion 32, and is fixed non-rotatably with a pin or the like.

At this time, the tube-shaped detector insertion support portion 36f penetrates the stepped jack end insertion hole 39a of the second support member 39 and projects rearward. The detector insertion support portion 36f is screwed and fixed with a nut in the large diameter portion, and the swing jack 36f is fixed.
Is fixed to the second support member 39 immovably. Also,
At this time, the pipe connection portions of the pressure oil inlet / outlet ports 36c and 36d of the swinging jack 36 are simultaneously inserted into the through holes 39b and 39c formed in the second support member 39, respectively. The pipe connection portions of the pressure oil input / output ports 36c, 36d are connected to a fixed pipe (not shown) inserted into the through holes 39b, 39c.

As shown in FIG. 4, the main body of the stroke detector 37 is housed in a tubular case 37a, the detection end 37b of which is extended forward and the rear end is connected to the electric cable 42. An electric cable 42 fixed to the rear end of the tubular case 37a is tightly fitted and fixed together with the rear end of the stroke detector 37 to the rear end of the tubular detector insertion support portion 36f via a seal ring 37c. You. On the other hand, the detection end 37b of the stroke detector 37 is fixed to the inside of the detector insertion hole 36g of the piston rod 36b by soldering or brazing. That is, the detection end 37b of the stroke detector 37
Is disposed on the axis of the piston rod 36b of the swinging jack 36 to which the detection end 37b is fixed.
The stroke detector 37 is spherically supported by the cutter head 31 together with the cylinder head 6b, and the rear end of the main body of the stroke detector 37 is fixedly mounted on the swing part 32 together with the cylinder tube 36a of the swing jack 36.

According to the swinging portion support structure of the small-diameter thruster according to the present embodiment having the above-described structure, one end of the swinging jack 36 is spherically supported by the cutter head portion 31 and the other end thereof is swinging. A plurality of spherical support portions at the end of the piston rod and a cutter head portion 31
And the connecting portion of the swing portion 32 are disposed substantially in the same plane,
Since the center of the swing of the front pipe 1 and the center of the circular plane formed by the plurality of spherical support parts are substantially coincident with each other, when the front pipe 1 swings as described above, particularly in the radial direction of the spherical support part, Swing amount becomes smaller than the swing amount of the front conduit 1,
Excavation can be performed smoothly and smoothly according to the setting, without rattling during curve excavation.

In this embodiment, a stroke detector 37 is mounted inside the swinging jack 36 along the axis thereof, and its detecting end 37b is integrated with the piston rod 36b of the swinging jack 36. And the connection end with the electric wire cable 40 is fixed to the bottom 36e of the cylinder tube 36a.
Similarly to the swing jack 36, the rear end is fixed to the swing portion 32, and the front end is spherically supported by the cutter head portion 31. Detection is possible, and the stroke amount is directly detected from the amount of expansion and contraction of the oscillating jack 36, so that extremely accurate detection is possible. Further, since the stroke detector 37 is built in the swinging jack 36, it is possible to very effectively use the internal space of the narrow front conduit 1.

In the first embodiment described above, the swinging jack 36
The case where the tip of the piston rod 36b is spherically supported by the cutter head 31 toward the front of the front pipe 1 and the bottom 36e of the cylinder tube 3a is fixed to the swing portion 32 has been described. The mounting direction of 36 can be reversed from that of the first embodiment.

FIGS. 6 and 7 schematically show such second and third embodiments. According to the second embodiment shown in FIG. 6, the rod 36e 'projects forward from the bottom 36e of the cylinder tube 36a of the swinging jack 36, and the projecting end is formed in the spherical portion 36a'. On the other hand, a flange portion 36b "is formed at the tip of the piston rod 36b of the swinging jack 36, and a pipe connection portion for hydraulic input / output ports 36c and 36d is formed in the flange portion 36". An accommodation section is provided.

In the third embodiment shown in FIG. 7, the basic structure of the swinging jack 36 is substantially the same as that of the first embodiment. However, in this embodiment, the piston rod 36b
Is spherically supported by the oscillating portion 32, so that a circular plane including a plurality of the spherical supporting portions forms a connecting portion between the cutter head portion 31 and the oscillating portion 32, that is, the seal member 3.
5 must substantially coincide with the circular plane formed by. Therefore, in the third embodiment, a connecting portion between the cutter head portion 31 and the swing portion 32 is arranged near the rear end of the swing jack 36 (the tip spherical portion 36b 'of the piston rod 36b).

FIGS. 8 and 9 show fourth and fifth embodiments relating to the arrangement position of the stroke detector 37 of the present invention. In the first to third embodiments, the case where the stroke detector 37 is incorporated in the swing jack 36 is exemplified. However, in the present invention, the stroke detector 37 is necessarily incorporated in the swing jack 36. You don't need that.

That is, as shown in FIG. 8, a plurality of swing jacks 36 and a plurality of stroke detectors 37 can be alternately arranged on the same circumference, or as shown in FIG. , A plurality of stroke detectors 37 may be arranged on the inside of a plurality of swing jacks 36 arranged on the circumference and concentric with the plurality of swing jacks 36. In this case, it is desirable that the plurality of stroke detectors 37 are disposed on the same radius as opposed to one swing jack 36 as shown in FIG. In arranging the stroke detector 37 in this manner, one end of the stroke detector 37 is connected to one of a pair of divided outer cylinders of the front conduit 1 connected front and back, similarly to the swing jack 36 described above. A spherical surface is supported, and the other end is fixed to the other divided outer cylinder.

As is apparent from the above description, the swinging portion support structure of the small-diameter thruster according to the present invention has at least one end of the swinging jack 36 swingably connected to the front and rear of the front conduit 1. By spherically supporting one end of a pair of divided outer cylinders and fixing the other end of the swinging jack 36 to the other divided outer cylinder immovably, the swinging jack or the like moves at the time of swinging, and other members are moved. Without interference, not only can the internal space of the narrow front pipe 1 be efficiently utilized, but also the rattling at the time of swing is extremely small, so that high-precision construction is possible.

In addition, the stroke detector 37, which is the swing amount detecting means, can be directly incorporated in the swing jack based on the above-described structure, so that the swing jack 1 can easily follow the swing operation of the swing jack. The amount can be directly detected as the amount of expansion and contraction of the stroke detector 37, and highly accurate detection becomes possible. The stroke detector 37 is installed on the concentric circle with the swinging jack 36, and one end is spherically supported on one of the divided outer cylinders similarly to the swinging jack, and the other end is set on the other divided outer cylinder. If it is fixed, it is not always necessary to incorporate it in the swinging jack as described above. As the stroke detector 37, besides a normal potentiometer, for example, a conductive plastic linear motion type (manufactured by Copal Electronics), an ultrasonic reflection type sensor, a linear displacement sensor with a back spring, or the like can be adopted.

As described above, the present invention can be variously modified, and is not limited to the above embodiment.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a main part of a leading pipe provided with a swinging part support structure of a small-diameter thruster according to a first embodiment of the present invention.

FIG. 2 is an internal side view of the leading pipe showing the swinging part support structure when the pipe is straight ahead.

FIG. 3 is an internal side view showing the swinging portion supporting structure when the leading conduit swings.

FIG. 4 is an enlarged side view showing a swinging jack and a stroke detector applied to the swinging portion support structure and a partly cutaway view of the support structure.

FIG. 5 is a rear view of the swinging jack.

FIG. 6 is a side view schematically showing a swinging portion support structure of a small-diameter thruster according to a second embodiment of the present invention.

FIG. 7 is a side view schematically showing a swinging portion support structure of a small-diameter thruster according to a third embodiment of the present invention.

FIG. 8 is an explanatory view showing another example of the arrangement of the swing jack and the stroke detector according to the present invention, wherein FIG. 8 (a) is a front view showing the arrangement, and FIG. It is arrow sectional drawing of the AA line.

FIG. 9 is an explanatory view similar to FIG. 8, showing yet another arrangement example of the swing jack and the stroke detector according to the present invention.

FIG. 10 is a side view showing an example of a supporting structure of a swinging part in a conventional small-diameter thruster.

FIG. 11 is a side view showing an example of another supporting structure of the swinging portion in the conventional small-diameter thruster.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead pipe 3 Swing part 20 Cutter head 21 Rotation axis 30 Cylindrical shield case 31 Cutter head part 31a Sliding member 32 Swing part 32a Sliding contact member 33 Pinch part 34 Rear end part 35 Seal member 36 Swing jack 36a Cylinder Tube 36a 'Spherical part 36b Piston rod 36b' Spherical part 36b "Flange part 36c, 36d (Pressure oil) inlet / discharge port 36e Bottom part 36e 'Rod 36f Detector insertion support part 36g Detecting end insertion fixing hole 37 Stroke detector 37a Tube Case 37b Detection end 37c Seal ring 38 First support member 38a Spherical support seat 39 Second support member 39a Stepped jack end insertion holes 39b, 39c Through hole 40 Screw casing 41 Screw 42 Electric cable 50 Pinch valve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Akiyama 5 Komatsu, Komatsu, Ishikawa Pref. Komatsu Plant Co., Ltd. (72) Inventor Tsuneo Sugihira 5 Kochi, Yokaichi, Ishikawa Pref. Komatsu Plant Komatsu Factory F-term (reference) 2D054 AA02 AC18 AD03 BA14 DA03 GA04 GA17 GA34 GA42 GA65 GA94

Claims (4)

[Claims] 1. A small-diameter bore in which a front conduit has two or more divided outer cylinders, at least one of a pair of front and rear divided outer cylinders is swingably connected and supported by a plurality of swing jacks. A swinging part support structure for a propulsion device, wherein one end of the swinging jack is fixed to one of the pair of divided outer cylinders, and the other end of the swinging jack is connected to the other divided outer cylinder. A swinging part support structure for a small-diameter thruster, which is spherically supported by a spherical supporting part. 2. A plane including the plurality of spherical support portions in a state where the pair of divided outer cylinders are liquid-tightly connected to each other via a sealing member, and in a state where a plurality of all swinging jacks are extended by a half stroke. 2. The swinging part support structure according to claim 1, wherein the seal member is disposed in the vicinity of. 3. The swing amount detecting means has one end spherically supported in a circular plane including a spherical support portion of the swinging jack, and the other end is fixed to one of the divided outer cylinders. Item 3. The swinging portion support structure according to Item 1 or 2. 4. The swing portion support structure according to claim 3, wherein said swing amount detecting means is built in said swing jack.