EP0937435A2

EP0937435A2 - Extension tube assembly for vacuum cleaner

Info

Publication number: EP0937435A2
Application number: EP99300647A
Authority: EP
Inventors: Seung Kon Kim
Original assignee: LG Electronics Inc; Kwang Dong Precision Co Ltd
Current assignee: LG Electronics Inc; Kwang Dong Precision Co Ltd
Priority date: 1998-02-23
Filing date: 1999-01-28
Publication date: 1999-08-25
Also published as: KR19990038822U; KR200164119Y1; EP0937435A3

Abstract

Extension tube assembly for a vacuum cleaner, is disclosed, of which length is adjustable with easy according to a user's height or ambient conditions, including an inner tube (20), an inner sleeve (40) movably fitted on an outer circumference of the inner tube (20) along an axis of the inner tube (20), an outer sleeve (60) rotatably fitted on an outer circumference of the inner sleeve (40) for fixing, or releasing the inner sleeve (40) to/from the inner tube at an arbitrary position along the axis of the inner body in moving the inner sleeve (40) along the axis of the inner tube (20) or fixing the inner sleeve at an arbitrary position along the axis of the inner tube (20), and an outer tube (90) fitted on the outer circumference of the inner sleeve at a rear portion thereof for moving together with the outer sleeve (60) and the inner sleeve (40).

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an extension tube assembly for a vacuum cleaner, and more particularly, to an extension tube assembly of which length is adjustable with easy according to a user's height or ambient conditions.

Background of the Related Art

Fig. 1 illustrates a disassembled perspective view of an exemplary related art vacuum cleaner, referring to which a related art extension tube assembly will be explained.
In general, an extension tube of a vacuum cleaner is disposed between a suction nozzle 3 which draws dusts and wastes and a suction hose 4 directly connected to a vacuum cleaner body 2 having a motor housed therein, on one side, for connecting the suction nozzle 3 to the vacuum cleaner body 2 and, on the other side, for serving as a handle for use in moving the suction nozzle. As shown in Fig. 1, the extension tube assembly 1a of a vacuum cleaner is a simple combination of connection tube 100a pieces; the connection tube pieces are inserted, and coupled to an appropriate number of pieces, for adjusting an overall length of the extension tube assembly to a desired length.
However, as explained, even though an overall length of the extension tube assembly in the related art vacuum cleaner is adjustable by selecting an appropriate number of the connection tube pieces 100a, the extension tube assembly has a structural limitation in adjusting an overall length as appropriate and as the user desired, freely. That is, because fixed lengths of the connection tube pieces 100a of the extension tube assembly 1a fixes a length of the extension tube assembly 1a, the user has a very small selection range in varying an overall length of the extension tube assembly. Moreover, when a length of the extension tube assembly is adjusted in the related art vacuum cleaner, each of the connection tube pieces 100a should be disassembled without fail, and the connection tube pieces should be assembled again to a desired length. According to this, the length adjusting in the related art extension tube assembly has been very cumbersome, and a suction power can be wasted when the length is adjusted while the vacuum cleaner is turned on as a flow between the vacuum cleaner body 2 and the suction nozzle 3 are disconnected during the extension tube assembly is detached.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed an extension tube assembly for a vacuum cleaner that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an extension tube assembly for a vacuum cleaner, in which a length adjustment can be made with easy freely for enhancing convenience, and of which fabrication is simple and frequency of go wrong can be reduced.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the extension tube assembly for a vacuum cleaner includes an inner tube having one side of an outer circumference with a plurality of stopping slots each elongated in a circumferential direction in the outer circumference at fixed intervals and the other side of the outer circumference with a longitudinally elongated sliding groove for prevention of rotation of the inner sleeve, an inner sleeve adapted to be inserted on an outer circumference of the inner tube for moving along an longitudinal direction of the inner tube, the inner sleeve having a stopper adapted to be elastic by means of the cut-away slots formed in an axis direction in the outer circumference, with a hook at a fore end thereof of a shape matched to the stopping slots in the inner tube, locking lips each with rounded edges at 90 degrees along the circumference in left and right directions from the stopper formed to be elastic by means of cut-away slots extended farther than the fore end of the stopper along the axis direction, and a sliding projection on an inner circumference thereof of a shape matched to the sliding groove in the inner tube for preventing rotation of the inner sleeve, an outer sleeve having locking slots at a fore end thereof opposite to each other in a circumferential direction, steps at the fore end thereof along the inner circumference between the locking slots projected inwardly, and locking lip escape grooves in an inner circumference continuous to the locking slots on one side of the steps for escape of the locking lips from the locking slots upon application of a rotating force to the outer sleeve in a state when the locking lips are positioned in respective locking slots, a ridge below each of the locking slots for preventing fall off of the outer sleeve from the inner sleeve and causing the outer sleeve and the inner sleeve to move together along axis of the inner tube in moving the outer sleeve, longitudinal stopper escape grooves for releasing locking of the stopper when the stopper comes thereon and stopper presses for locking the stopper when the stopper comes thereon, both in the inner circumference below the steps along the circumferential direction, the outer sleeve adapted to be rotatably inserted on the inner sleeve and the expanded tube portion only exposing the locking lips on the inner sleeve, thereby pressing the stopper to prevent escape of the hooks from the stopping slot or releasing the stopper to allow the hooks to ride over the stopping slot depending on whether the locking lips are in the locking slots or not, and an outer tube having an expanded tube portion for pressing and inserting the inner sleeve therein up to a position the stopper and the locking lips are exposed, for moving along an axis direction of the inner tube together with the inner sleeve when the locking of the stopper is released and the inner sleeve is moved along the axis of the inner tube under a state the inner sleeve and the expanded tube portion are coupled.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention:
In the drawings:
Fig. 1 illustrates a disassembled perspective view of an exemplary related art vacuum cleaner;
Figs. 2A ~ 2C illustrate perspective views showing steps of assembling an extension tube assembly in accordance with a preferred embodiment of the present invention, wherein,
Fig. 2A illustrates a disassembled perspective view of an extension tube assembly in accordance with a preferred embodiment of the present invention,
Fig. 2B illustrates a disassembled perspective view showing a preliminary assembly of an extension tube assembly in accordance with a preferred embodiment of the present invention, and
Fig. 2C illustrates a perspective view showing a fully assembled extension tube assembly in accordance with a preferred embodiment of the present invention;
Fig. 3 illustrate a front perspective view of an inner tube;
Fig. 4 illustrates a section across line I-I in Fig. 3;
Fig. 5 illustrates a perspective view of an inner sleeve;
Fig. 6 illustrates a perspective view of an outer sleeve;
Fig. 7 illustrate a perspective view of an outer tube;
Figs. 8A and 8B, and 9A ~ 9B respectively illustrate perspective views and cross sectional views for explaining the extension tube assembly of the present invention in locked and unlocked states, wherein,
Fig. 8A illustrates a perspective view in a locked state,
Fig. 8B illustrates a perspective view when the locked state is released,
Fig. 9A illustrates a section across line II - II in Fig. 8A, and
Fig. 9B illustrates a section across line III - III in Fig. 8B;
Fig. 10A ~ 10E illustrate sections showing the steps of adjusting a length of the extension tube assembly of the present invention, wherein,
Fig. 10A illustrates a section across line IV - IV in Fig. 9A showing a locked state,
Fig. 10B illustrates a section across line V - V in Fig. 9B showing a lock released state,
Fig. 10C illustrates a section showing a stopper passing through a region between stopping slots in shortening a length of the extension tube assembly by handling an outer sleeve in a state of Fig. 10B,
Fig. 10D illustrates a section showing a stopper fitted in a desired stopping slot by a user's length adjustment, and
Fig. 10E illustrates a section showing a locked state restored again after finish of length adjustment; and,
Fig. 11 illustrates an extension tube assembly of the present invention fitted to a vacuum cleaner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
Referring to Figs. 2A and 2C, an extension tube assembly in accordance with a preferred embodiment of the present invention includes an inner tube 20, an inner sleeve 40 movably fitted on an outer circumference of the inner tube 20 along an axis of the inner tube 20, an outer sleeve 60 rotatably fitted on an outer circumference of the inner sleeve 40 for fixing, or releasing the inner sleeve 40 to/from the inner tube 20 at an arbitrary position along the axis of the inner body 20 in moving the inner sleeve 40 along the axis of the inner tube 20 or fixing the inner sleeve 40 at an arbitrary position along the axis of the inner tube 20, and an outer tube 90 fitted on the outer circumference of the inner sleeve 40 at a rear portion thereof for moving together with the outer sleeve 60 and the inner sleeve 40.
Referring to Fig. 3, the inner tube 20 has a plurality of stopping slots 20 each formed in the outer circumference in a circumferential direction at fixed intervals in axis direction and, as shown in Fig. 4, a sliding groove 20b along the axis thereof in the outer circumference opposite to the stopping slots 20a.
Referring to Fig. 5, the inner sleeve 40 has a stopper 40a formed elastic by means of axial cut-away slots 40c with a hook 400a at a fore end thereof formed to be matched to the stopping slot 20a in the inner tube 20 when the inner sleeve 40 is mounted on the inner tube 20, locking lips 40b at 90 degrees along the circumference in left and right directions from the stopper 40a formed to be elastic by means of cut-away slots 40g each with a hook 400b projected outwardly at a fore end thereof and extended farther than the fore end of the stopper 40a along the axis direction, and a sliding projection 40e on an inner circumference thereof for sliding on the sliding groove 20b in the outer circumference of the inner tube 20 and preventing rotation of the inner sleeve 40. The sliding projection 40e for sliding on the sliding groove 20b is elongated in axial direction. And, the hook 400b on each of the locking lips 40b has rounded edges. And, as shown in Fig. 10A, there is a lip 40f opposite to the stopper 40a on the inner sleeve 40 extended farther by a length ℓ for prevention of contact and interference between an inner surface of a step 53 and the fore end of the stopper 40a when the stopper 40a is elastically deformed.
Referring to Fig. 6, the outer sleeve 60 has locking slots 52 at a fore end thereof opposite to each other in a circumferential direction, a step 53 at the fore end thereof between the locking slots 52 projected inwardly, and locking lip escape grooves 530 continuous to the step 53 for escape of the hooks 400b on the locking lips 40b from the locking slots 52 along the inner circumference of the outer sleeve 60 at application of a rotating force to the outer sleeve 60 in a state when the hooks 400b on the locking lips 40b are positioned in respective locking slots 52. There is a ridge 53a below each of the locking slots 52 and the locking lip escape grooves 530 in the outer sleeve 60 for preventing fall off of the outer sleeve 60 from the inner sleeve 40 by preventing the hooks 400b from being coming off from the locking lip escape grooves 530 in association with the steps 53 above the locking lip escape grooves 530 as well as causing the outer sleeve 60 and the inner sleeve 40 to move together along axis of the inner tube 20 in an adjustment of a length of the extension tube assembly. And, there are longitudinal stopper escape grooves 55 for releasing locking of the stopper 40a when the stopper 40a comes thereon and, in continuation to the stopper escape grooves 55 in the circumferential direction, stopper presses 56 for locking the stopper 40 when the stopper 40a comes thereon. Therefore, when the outer sleeve 60 and the inner sleeve 40 are assembled together, the inner sleeve 40 is rotatably inserted in the outer sleeve 60, exposing the hooks 400b on the locking lips 40b through the locking slots 52, thereby pressing the stopper 40a to prevent escape of the hooks 400a from the stopping slot 20a or releasing the stopper 40a to allow the hooks 400a to ride over the stopping slot 20a depending on whether the locking lips 40b are in the locking slots 52 or not. There are anti-friction projections 600 of dot forms on outer circumferences of the outer sleeve 60 for prevention of slippage at adjustment of the length of the extension tube assembly, for easy handling of the outer sleeve 60.
Referring to Fig. 7, the outer tube 90 has an expanded tube portion 90a at one end thereof for pressed insertion of the inner sleeve 40 up to a position where the stopper 40a and the locking lips 40b are exposed, for moving the inner sleeve 40 together with the outer sleeve 60 along axis of the inner tube 20 when the locking of the stopper 40a is release and moving the inner sleeve 40 and the outer sleeve 40 are moved along the axis of the inner tube while the inner sleeve 40 and the expanded tube portion 90a of the outer tube 90 are assembled. The inner sleeve 40 is formed of an elastic material for an appropriate bending of the stopper 40a and the locking lips 40b upon exertion of force thereto and restoring to an original state upon releasing the force. The inner tube 20 and the outer tube 90 are preferably formed of a steel, such as stainless steel with a long lifetime. And, contact surface in rotation of the locking slots 52 in the outer sleeve 60 and the locking lips 40b on the inner sleeve 40 are rounded for an easy escape of the hooks 400b on the locking lips 40b into the locking lip escape grooves 530 adjacent to the locking slots 52 and held between the steps 53 and the ridges 53a when an appropriate rotational force is applied to the outer sleeve 60. The stopper escape grooves 55 are recessed in the inner circumference below the step 53 for escape of the stopper 40a when the hook 400a on the fore end of the stopper 40a rides over the slots 20a in the inner tube 20 in a length adjustment of the extension tube assembly. The stopper escape grooves 55 have a depth for the stopper 40a to make an elastic deformation enough to escape from the slot 20a in the length adjustment. And, there is a baffle 530a at one end of each of the locking lip escape grooves 530 for blocking the locking lips 40b, preventing further rotation of the stopper 40a and confining a rotation range of the outer sleeve 60. And, as one embodiment for prevention of unintended separation of the inner sleeve 40 from the outer tube 90, there are a recess 40d and a guide groove 40h in one side of the inner sleeve 40 and, to correspond to the recess 40 and the guide groove 40h, a nipple 900 on one side of the expanded tube portion 90a of the outer tube 90. There is a packing 70 at a fore end of the inner tube 20 for keeping air tight between the inner tube and the outer tube. And, it is preferable to fit a plastic tube piece 10 to an expanded tube coupling portion 15 at a fore portion of the inner tube 20 for easy coupling of the suction nozzle 3 thereto shown in Fig. 11.
The steps for assembling the extension tube assembly of the present invention will be explained with reference to Figs. 2A ~ 2C.
The step is started with inserting the plastic tube piece 10 into the expanded tube coupling portion 15 so that the inner tube 20 can be firmly coupled with the suction nozzle 3 which is assembly later. Then, after inserting the outer sleeve 60 on around the inner tube 20, and the outer sleeve is placed at the expanded tube coupling portion 15, for the time being. The outer sleeve 60 is assembled and placed at the expanded tube coupling portion 15 at first, because the locking lips 40b on the inner sleeve 40 can be disposed in the locking slots 52 in the outer sleeve 60 only when the inner sleeve 40 is inserted into the outer sleeve 60 from rear side of the outer sleeve 60 opposite to the locking slots 52 under a state the inner sleeve 40 is inserted on the inner tube 20, later. While the outer sleeve 60 is placed at the expanded tube coupling portion 15 on the inner tube 20, as shown in Fig. 2B, the inner sleeve 40 is inserted on around the inner tube 20 with the sliding groove 20b recessed in the outer circumference of the inner tube 20 and the sliding projection 40e provided for a circumferential rotation of the inner sleeve 40 matched. The sliding groove 20b and the sliding projection 40e provides a direction to the stopper 40a on the inner sleeve 40 to move along a line of the stopping slots 20a in the inner tube 20. Then, a packing is fitted to the inner tube 20 at a side opposite to the expanded tube coupling portion 15 for maintaining an air tightness between the inner tube 20 and the outer tube 90. The inner sleeve 40 is moved along the axis direction of the inner tube 20, and the stopper 40a is locked at one stopping slot 20a in the inner tube 20. Then, the inner sleeve 40 is inserted into the expanded tube portion 90a on the outer tube 90 until the nipple 900 on the expanded tube portion 90a, passed through the guide groove 40h, is locked into the recess 40d, for a firm coupling of the inner tube 40 and the outer tube 90. Under this state, the outer sleeve 60 is pushed forward toward the packing 70, thereby coupling the outer sleeve 60 on an outer circumference of the inner sleeve 40. When the locking lips 40b on the inner sleeve 40 and the locking slots 52 in the outer sleeve 60 are arranged on a straight line and the outer sleeve 60 is pushed onto the inner sleeve 40, the hooks 400b on the locking lips 40b on the inner sleeve 40 are blocked at the ridges 53a below the locking slots 52 once, and, on exerting a further force thereto, the hooks 400b are snap fitted into the locking slots 52 as the locking lips 40b make a elastic deformation. Thus, when the inner sleeve 40 and the outer sleeve 60 are assembled, with the locking lips 40b on the inner sleeve 40 exposed through the locking slots 52 in the outer sleeve 60, the stopper press 56 on the inner circumference of the outer sleeve 60 presses onto the stopper 40a, thereby the stopper 40a locking on the inner tube 20. Thus, assembly of the extension tube assembly of the present invention is completed.
The steps of a length adjustment of the extension tube assembly of the present invention will be explained, with reference to Figs. 8A ~ 10E.
Referring to Figs. 8A, 9A, and 10A, in order to make a length adjustment of the extension tube assembly 1 from an initial state when the stopper 40a is locked on an arbitrary stopping slot 20a in the inner tube 20, an appropriate rotational force is applied to the outer sleeve 60 to rotate the outer sleeve 60 in a direction to release the locking of the stopper 40a. In this instance, the inner sleeve 40 does not rotate as the sliding projection 40e is fitted in the guide groove 20b in the inner tube 20, and, instead, the outer sleeve 60 rotates around the inner sleeve 40. According to this, as shown in Fig. 9B, the right and left locking lips 40b on the inner sleeve 40 move into the locking lip escape grooves 530 in the inner circumference of the outer sleeve 60 formed continuous to one side of the locking slots 52. On the same time with this, as shown in Fig. 9B and 10B, the stopper 40a on the inner tube 40 leaves the stopper press 56 which presses the stopper 40a and comes into the stopper escape grooves 55. Under this condition, if the user either pushes forward, or pull back the outer sleeve 60, making the outer tube 20 to move on the inner tube 20, the length of the extension tube assembly can be adjusted as the user intended. In this instance, the elastic deformation of the stopper 40a on the inner sleeve 40 at escape from the stopping slot 20a into the stopper escape grooves 55 permits the ride of the stopper 40a over the stopping slots 20a in the inner tube 20. For example, if the inner sleeve 40 is rotated in a direction of an arrow from a locked state shown in Fig. 10A, releasing the locking on the stopper 40a as shown in Fig. 10B and disposing the stopper 40a in the stopper escape groove 55 in the outer sleeve 60, and, if the outer sleeve 60 is then advanced toward right side on the drawing as shown in an arrow in Fig. 10B, the inner sleeve 40 and the outer tube 90 are moved to the right side along the axis of the inner tube 20 guided by the inner tube 20, together with the outer sleeve 60. In this instance, the stopper 40a makes an elastic deformation as shown in Fig. 10C as the stopper 40 escapes from the stopping slot 20a in the inner tube 20, and the stopper 40a restores to an original form as the hook 400a on the stopper 40a is inserted into a desired stopping slot 20a as shown in Fig. 10D. This elastic deformation of the stopper 40a is of course permitted by the adequate depth of the stopper escape grooves 55 as shown in "d" in Figs. 9B and 10B, and, as shown in Fig. 10A, the lip 40f extended farther than the stopper 40a is brought into contact with the inner surface of the step 53 at first, spacing the fore end of the stopper 40a from the inner surface of the step 53, the contact and interference of the stopper 40a with the inner surface of the step 53 is prevented when the stopper makes the elastic deformation. In the meantime, as shown in Fig. 10D, if the outer sleeve 60 is rotated in a locking direction from a state when the length adjustment of the extension tube assembly 1 is completed by inserting the stopper 40a into a desired stopping slot 20a, the locking lips 40b on the inner sleeve 40 move into the locking slots 52 in the outer sleeve 60 again as shown in Figs. 8A and 9A, and, on the same time, the stopper 40a on the inner sleeve 40 leaves the stopper escape groove 55 and engages with the stopper press 56. And, as shown in Fig. 10E, because the hook 400a on the stopper 40a can not be disengaged from the stopping slot 20a due to the pressing force from the stopper press 56 under a state the stopper 40a is engaged with the stopper press 56, the length of the extension tube assembly is set as the user desired.
Since a minimum adjustable unit length of the extension tube assembly 1 is a pitch of the stopping slots 20a, the extension tube assembly may be varied freely as the user desired to a length convenient to the user. Fig. 11 illustrates an extension tube assembly of the present invention fitted to a vacuum cleaner.
In the meantime, if it is intended to store components of the extension tube assembly 1, the outer sleeve 60 is rotated in one direction, to release the locking between the stopper 40a on the inner sleeve 40 and the stopping slot 20a in the inner tube 20, and the inner tube 20 is pulled to separate the inner tube 20 from the inner tube 40 that is seized in the outer tube 90. Then, in separating the outer sleeve 60 from the inner sleeve 40, first the locking lips 40b on the inner sleeve 40 are brought into the locking slots 52 in the outer sleeve 60, and, then, the locking lips 40b are pressed inwardly, to cause the hooks 400b on the locking lips 40b to escape from the locking slots 52, and pressed downwardly, so that the locking lips 40b can escape from the locking slots 52. Then, upon pulling the outer sleeve 60 in axial direction, the outer tube 90 is separated from the inner sleeve 40 coupled to the outer tube 90. Thus, the inner tube 20, the outer sleeve 60, and the inner sleeve 40 coupled to the outer tube 90 may be separated for separate storage as the user wanted.
The extension tube assembly of the present invention has the following advantages.
An overall length of the extension tube assembly can be adjusted to be appropriate to a height of the user or an ambient condition by interconnecting the inner tube 20 and the outer tube 90 with an outer sleeve 60 and an inner sleeve additionally provided between the inner tube 20 and the outer tube 90 of steel in the extension tube assembly 1. According to this, the convenience in adjusting the length of the extension tube assembly according to the user's own height or an ambient condition in the present invention can improve conveniences in view of operations and functions of the vacuum cleaner, significantly. Moreover, the simple injection molding of the inner sleeve and the outer sleeve in the length adjusting device in the extension tube assembly allows a simple fabrication process. And, the only two components required for the length adjusting of the extension tube assembly allows simple assembly, and disassembly, and reduces chances of go wrong of the assembly.
It will be apparent to those skilled in the art that various modifications and variations can be made in the extension tube assembly for a vacuum cleaner of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

An extension tube assembly for a vacuum cleaner, comprising:

an inner tube having a plurality of stopping slots each formed in an outer circumference thereof at fixed intervals in axis direction;

an inner sleeve movably fitted on an outer circumference to be movable along an axis of the inner tube and having a stopper with a hook thereon for inserting into the stopping slot in the inner tube;

an outer sleeve rotatably fitted on an outer circumference of the inner sleeve for fixing, or releasing the inner sleeve to/from the inner tube at an arbitrary position along the axis of the inner body in moving the inner sleeve along the axis of the inner tube or fixing the inner sleeve at an arbitrary position along the axis of the inner tube; and,

an outer tube fitted on the outer circumference of the inner sleeve at a rear portion thereof for moving along the inner tube, together with the inner sleeve.
An extension tube assembly as claimed in claim 1, wherein the inner tube has a sliding groove in the outer circumference along the axis opposite to the stopping slots, and the inner sleeve has a sliding projection on an inner circumference in conformity with the sliding groove in section, thereby preventing rotation of the inner sleeve around the inner tube after assembly of the inner sleeve on the inner sleeve.
An extension tube assembly as claimed in claim 1, wherein the outer sleeve has a longitudinal stopper escape groove in the inner circumference thereof and a stopper press formed on the inner circumference continuous to the stopper escape groove in an inner circumference direction, for releasing a confinement on the stopper to the outer sleeve as an elastic deformation of the stopper is made possible when the stopper is positioned in the stopper escape groove and, on the other hand, confining the stopper to the outer sleeve when the stopper is positioned at the stopper press.
An extension tube assembly as claimed in claim 1, wherein the inner sleeve includes locking lips at 90 degrees along the circumference in left and right directions from the stopper, the locking lips formed to be elastic by means of cut-away slots, and extended farther than the fore end of the stopper along the axis direction and having rounded edges, and the outer sleeve rotatably inserted on the inner sleeve includes locking slots adapted to expose only hooks on fore ends, thereby lock or release of the stopper being known to a user depending on whether the hook on the locking lips are present in the locking slots or not.
An extension tube assembly as claimed in claim 4, wherein the outer sleeve includes steps formed between the locking lips projected toward a center of the outer sleeve, and

locking lip escape grooves recessed along a circumferential direction adjoining to the locking lips in the steps,

thereby allowing the outer sleeve and the inner sleeve to move along the axis of the inner tube together when an appropriate rotating force is applied to the outer sleeve, so that the hooks on the locking lips slide into the locking lip escape grooves adjoining to the locking slots to position the hooks on the locking lips on the inner sleeve between the upper walls of the locking lip escape groove of the steps and the ridges formed below the escape grooves.
An extension tube assembly as claimed in claim 5, wherein the outer tube includes a baffle inside of the locking lip escape grooves for blocking the locking lips, preventing any further rotation of the stopper and confining a rotation range of the outer sleeve.
An extension tube assembly as claimed in claim 5, wherein the outer sleeve has a ridge formed below each of the locking lip escape groove and extended to portions below the locking slots for snap fitting the locking lips into the locking slots when the outer sleeve and the inner sleeve are assembled.
An extension tube assembly as claimed in claim 1, wherein the inner sleeve includes a recess in an outer circumference of the inner sleeve and, to correspond to the recess, a nipple on an inner circumference of the expanded tube portion of the outer tube for preventing separation of the inner sleeve from the outer tube coupled thereto.
An extension tube assembly as claimed in claim 1, wherein the inner tube is formed of an elastic material for allowing each of the stopper and the locking lips being bent to an appropriate extent upon application of a force thereto and being restored to an original state upon releasing the force.
An extension tube assembly as claimed in claim 1, wherein the inner tube and the outer tube are formed of a metal with a long lifetime.
An extension tube assembly as claimed in claim 10, wherein the inner tube and the outer tube are formed of stainless steel.
An extension tube assembly as claimed in claim 1, wherein there is a packing at one fore end of the inner tube for keeping air tight between the inner tube and the outer tube.
An extension tube assembly as claimed in claim 1, wherein the outer sleeve has a plurality of friction projections for prevention of slipping in handling of the outer sleeve.
An extension tube assembly for a vacuum cleaner, comprising:

an inner tube having one side of an outer circumference with a plurality of stopping slots each elongated in a circumferential direction in the outer circumference at fixed intervals and the other side of the outer circumference with a longitudinally elongated sliding groove for prevention of rotation of the inner sleeve;

an inner sleeve adapted to be inserted on an outer circumference of the inner tube for moving along an longitudinal direction of the inner tube, the inner sleeve having a stopper adapted to be elastic by means of the cut-away slots formed in an axis direction in the outer circumference, with a hook at a fore end thereof of a shape matched to the stopping slots in the inner tube, locking lips each with rounded edges at 90 degrees along the circumference in left and right directions from the stopper formed to be elastic by means of cut-away slots extended farther than the fore end of the stopper along the axis direction, and a sliding projection on an inner circumference thereof of a shape matched to the sliding groove in the inner tube for preventing rotation of the inner sleeve;

an outer sleeve having locking slots at a fore end thereof opposite to each other in a circumferential direction, steps at the fore end thereof along the inner circumference between the locking slots projected inwardly, and locking lip escape grooves in an inner circumference continuous to the locking slots on one side of the steps for escape of the locking lips from the locking slots upon application of a rotating force to the outer sleeve in a state when the locking lips are positioned in respective locking slots, a ridge below each of the locking slots for preventing fall off of the outer sleeve from the inner sleeve and causing the outer sleeve and the inner sleeve to move together along axis of the inner tube in moving the outer sleeve, longitudinal stopper escape grooves for releasing locking of the stopper when the stopper comes thereon and stopper presses for locking the stopper when the stopper comes thereon, both in the inner circumference below the steps along the circumferential direction, the outer sleeve adapted to be rotatably inserted on the inner sleeve and the expanded tube portion only exposing the locking lips on the inner sleeve, thereby pressing the stopper to prevent escape of the hooks from the stopping slot or releasing the stopper to allow the hooks to ride over the stopping slot depending on whether the locking lips are in the locking slots or not; and,

an outer tube having an expanded tube portion for pressing and inserting the inner sleeve therein up to a position the stopper and the locking lips are exposed, for moving along an axis direction of the inner tube together with the inner sleeve when the locking of the stopper is released and the inner sleeve is moved along the axis of the inner tube under a state the inner sleeve and the expanded tube portion are coupled.
A vacuum cleaner comprising an extension tube assembly, the extension tube assembly being in accordance with any preceding claim.