The present invention relates generally to the field of tele ^¬ scopic tubes. More specifically, the present invention is relat- ed to a telescopic tube which is adapted to be locked in differ ^¬ ent lengths by means of a locking mechanism.

BACKGROUND OF THE INVENTION Telescopic tubes with rotating mechanisms are known in prior art. A known telescopic tube comprises multiple tube elements which are usually formed by metal tubes. A first end of a first tube element is coupled with a first end of a second tube ele ^¬ ment by clamping elements made of rubber in order to provide a frictional connection.

Disadvantageously, the holding force between said tube elements depends on the power of the user. For example, for irrigation purposes the known clamping technigue is unsuitable because in case of high liguid pressure, the telescopic tube is extended uncontrollably. In addition, the telescopic coupling between the tube elements comprises multiple different parts (e.g. two tube elements, at least one nut and at least one clamping element) . Therefore manufacturing of said tube element is expensive.

SUMMARY OF THE INVENTION

It is an objective of the embodiments of the invention to pro ^¬ vide a telescopic tube which provides a solid and stable cou- pling between the tube elements with reduced manufacturing costs. The objective is solved by the features of the independ ^¬ ent claim. Preferred embodiments are given in the dependent claims. If not explicitly indicated otherwise, embodiments of the invention can be freely combined with each other. According to an aspect of the invention, the invention relates to a telescopic tube. The telescopic tube comprises at least an outer and an inner tube element. The telescopic tube may com ^¬ prise even more than two tube elements, wherein between the out- er tube element (comprising the greatest tube diameter) and the inner tube element (comprising the smallest tube diameter) at least one further tube element (comprising a tube diameter be ^¬ tween the greatest and the smallest tube diameter) is arranged. The outer tube element comprises at least one first clamping surface, said first clamping surface being arranged in a recess or groove within a first protrusion or on top of the first pro ^¬ trusion. Said first protrusion is provided at the inner wall side of the outer tube element, i.e. the first protrusion pro ^¬ trudes from the circular wall of the outer tube element into the interior of the outer tube element. The inner tube element com ^¬ prises at least one second clamping surface, said second clamp ^¬ ing surface being arranged in a recess or groove within at least one second protrusion or on top of said at least one second pro ^¬ trusion. Said second protrusion is provided at the outer wall side of the inner tube element, i.e. protrudes outwardly from the tube wall of the inner tube element. The second clamping surface is adapted to interact with the first clamping surface such that the tube elements are fixed against each other by clamping in a first turning position of the outer tube element with respect to the inner tube element (in the following also referred to as locked state) and are telescopable in a second turning position of the outer tube element with respect to the inner tube element (in the following also referred to as un ^¬ locked state) . In addition, a first stop portion is provided at the inner wall side of the outer tube element, said first stop portion interacting with a second stop portion provided at the outer wall side of the inner tube element, said stop portions providing stop means to limit the angle of rotation by which the tube elements can be rotated relative to each other. Advantageously, in the clamped, locked state, by means of the clamping surfaces a rigid, bend-proof and backlash-free connec ^¬ tion between the tube elements is obtained, i.e. in the locked state there is no or essentially no wobbling of the tube ele- ments. The stop portions provide means for driving further tube elements located between the outer and the inner tube elements when rotating or twisting said tube elements because when said stop portions abut against each other, the further tube elements are rotated or twisted thereby locking/unlocking the coupling between the further tube element and the outer/inner tube ele ^¬ ment. In other words, due to the stop portions, by rotating the outer and the inner tube element against each other, all cou ^¬ plings between tube elements of the telescopic tube can be un ^¬ locked, respectively, locked.

According to embodiments, in the locked, clamped state there is a form fit between a recess or groove provided within the first protrusion and the portion of the second protrusion forming the second clamping surface. The second clamping surface may be pro- vided at least partially on top of said second protrusion. More in detail, by rotating or twisting the tube elements against each other (from unlocked state into the locked state), at least a portion of the second protrusion comprising the second clamp ^¬ ing surface may be inserted in at least one recess or groove provided in the first protrusion. Thereby, the clamping surfaces abut against each other and when further rotating or twisting the tube elements against each other, the clamping surfaces are clamped against each other. The width of the recess or groove may be adapted to the width of the portion of the second protru- sion being inserted into said recess or groove such that a lat ^¬ eral form-fit (i.e. in axial direction of the tube elements) be ^¬ tween the recess or groove and at least one portion of the sec ^¬ ond protrusion is obtained. Thereby, the telescopic tube is adapted to withstand a high axial load, for example caused by a high liguid pressure within the telescopic tube. According to another embodiment, in the clamped state there is a form fit between the portion of the first protrusion forming the first clamping surface and a recess or groove provided in the second protrusion. In other words, there can be also a vice ver ^¬ sa - configuration wherein the second protrusion provided at the inner tube element comprises said recess or groove and the first protrusion provided at the outer tube element comprises a first protrusion forming the first clamping surface at least partially on top of said first protrusion.

Preferably, the first and/or second clamping surface comprises an eccentric shape. For example, the clamping surface provided at the top portion of the first or second protrusion may be cir- cumferentially arranged wherein the radial distance between the centre of the cross section of the tube element comprising said protrusion changes along said circumferentially arranged clamp ^¬ ing surface. Thereby, an effective clamping mechanism is ob ^¬ tained which can be manufactured easily and cost-effectively.

According to an embodiment, the depth of the at least one recess or groove decreases from a first groove end to a second groove end and/or the height of the first or second protrusion increas ^¬ es from a first protrusion end to a second protrusion end. In other words, the recess or groove, respectively, the first or second protrusion comprises a tapered shape. Thereby, an effec ^¬ tive clamping between the tube elements is obtained.

According to an embodiment, the first protrusion comprises a plurality of grooves (also referred to as recesses) and first clamping surfaces are formed at the bottom surfaces of said grooves . Alternatively, the first protrusion comprises a plural ^¬ ity of webs (also referred to as rips) and first clamping sur ^¬ faces are formed at the top surfaces of said webs. Also a combi- nation may be possible, i.e. clamping surfaces are formed at the top surfaces of said webs and clamping surfaces are also formed at the bottom surfaces of said grooves located between said webs. The webs and/or grooves may be orientated circumferential- ly. In other words, the first protrusion comprises at least par- tially a comb-like shape forming said webs and/or grooves. By means of said plurality of webs and/or grooves, an effective clamping and form-fit between adjacent tube elements is ob ^¬ tained. According to an embodiment, the second protrusion comprises a plurality of webs (also referred to as rips) and said second clamping surfaces are formed at the top surfaces of said webs. Alternatively, the second protrusion comprises a plurality of grooves (also referred to as recesses) and second clamping sur- faces are formed at the bottom surfaces of said grooves . Also a combination may be possible, i.e. clamping surfaces are formed at the top surfaces of said webs and clamping surfaces are also formed at the bottom surfaces of said grooves located between said webs. The webs and/or grooves may be orientated circumfer- entially. In other words, the second protrusion comprises at least partially a comb-like shape forming said webs and/or grooves. By means of said plurality of webs and/or grooves, an effective clamping and form-fit between adjacent tube elements is obtained.

According to an embodiment, the webs of the second protrusion are adapted to engage into the grooves of the first protrusion or the webs of the first protrusion are adapted to engage into the grooves of the second protrusion. In other words, a mechani- cal interlocking between the webs and grooves is obtained which leads to a rigid and bend-proof form-fit between the tube ele ^¬ ments .

According to an embodiment, the first protrusion includes a first protrusion portion comprising said grooves or webs and a second, solid protrusion portion wherein the second, solid pro ^¬ trusion portion builds said first stop portion. In other words, the stop portion and the protrusion comprising the grooves or webs are formed by the same protrusion, namely the first protru- sion. The stop portion may be arranged at a protrusion portion opposite to the protrusion portion comprising the grooves or webs. Thereby, a simple structure of the tube element is ob ^¬ tained. According to an embodiment, the free ends of the webs of the second protrusionbuild the second stop portion. In the unlocked state, at least some of said free ends may rest against the first stop portion and thereby block a further rotation/twisting of the tube elements.

According to an embodiment, the free ends of the webs being in- sertable into the grooves may also form a stop portion. Said free ends may abut against end portions of said grooves thereby blocking a further clamping in order to avoid damages due to high clamping forces .

According to an embodiment, multiple first protrusions are cir ^¬ cumferentially distributed at the inner wall side of the outer tube element, wherein the dimensions of the gaps between adja- cent first protrusions are adapted to the circumferential dis ^¬ tribution and dimensions of multiple second protrusions provided at the outer wall side of the inner tube element such that the inner tube element is axially displaceable with respect to the outer tube element in the unlocked state. In other words, in case that the tube elements comprise a rotation position such that the second protrusions are located (in circumferential di ^¬ rection) in said gaps provided at the inner wall side of the outer tube element, the telescopic tube is telescopable . Due to the usage of multiple circumferentially distributed protrusions, the coupling between the tube elements is increased. According to an embodiment, the second protrusion comprising a plurality of webs extends axially along the whole or essentially the whole axial length of the inner tube element . Thereby, the ad ustability of length of the telescopic tube is significantly increased .

According to an embodiment, a spring is operably arranged be ^¬ tween the first and second protrusion in order to maintain the clamped state or at least in order to maintain an engagement of the second protrusion within the recess or groove provided in the first protrusion or in order to maintain an engagement of the first protrusion within the recess or groove provided in the second protrusion. The spring may be a leg spring. Said spring may be made of spring steel or plastic. Thereby, an undesired extension of the telescopic tube, for example when applying high liquid pressure to the telescopic tube is obtained.

According to an embodiment, the second, solid protrusion portion of the first protrusion comprises an end portion with an at least partially slanted edge. Said edge may be slanted with re ^¬ spect to the longitudinal axis of the telescopic tube by an an ^¬ gle a, wherein a is in the range between 30° and 60°, preferably between 40° and 50°, most preferably equal or essentially equal to 45°. The angle a may open towards the free end of the tube element adjacent to the slanted edge. Thereby a self-cleaning mechanism for removing dust is obtained in order to clean the gap between the stop portions which exists in the locked state of the telescopic tube.

According to another embodiment, there is a sealing element be ^¬ tween the outer and the inner tube element in order to provide a liquid-tight transition between the interior of the outer tube element and the inner tube element. Thereby, the telescopic tube may be used as liquid guide, for example, for spraying apparat ^¬ uses .

According to a further aspect, a bellows is arranged within the inner tube element in order to provide a liquid channel through said telescopic tube. Said bellow is advantageous because of its robustness, great liquid tightness, frost robustness and dirt resistance. Also, angel adjustable coupling means may be bridged by said bellows. By means of said bellows, sealing elements be- tween the tube elements for achieving a liquid tightness of the telescopic tube are not required.

According to a further aspect, the invention relates to a spray ^¬ ing apparatus, specifically to a hand-held spraying apparatus, e.g. a spray gun. Said spraying apparatus may comprise a tele ^¬ scopic tube as described before. Specifically, the telescopic tube may be arranged between the hand portion and a spray head of the spraying apparatus . According to yet a further aspect, the invention relates to a telescopic tube comprising at least an outer and an inner tube element. Said outer tube element comprises at least one first clamping surface, said first clamping surface being arranged on top of a first protrusion. Said first protrusion is provided at the inner wall side of the outer tube element. In addition, the inner tube element comprises at least one second clamping sur ^¬ face, said second clamping surface being arranged on top of at least one second protrusion. Said second protrusion is provided at the outer wall side of the inner tube element. Furthermore, said second protrusion is formed by an elastically deformable material layer. Said second clamping surface is adapted to in ^¬ teract with the first clamping surface such that the tube ele ^¬ ments are fixed against each other by clamping in a first turn ^¬ ing position of the outer tube element with respect to the inner tube element and are telescopable in a second turning position of the outer tube element with respect to the inner tube ele ^¬ ment, Said clamping in said first turning position is obtained by pushing said first protrusion into said elastically deforma ^¬ ble second protrusion when rotating the outer and an inner tube elements against each other from the second turning position in to the first turning position. In other words, the clamping of the inner and outer tube element is obtained by pushing one or more first protrusions into the elastically deformable material layer forming the second protrusion. Thereby, in the clamped state, a form-fit is obtained by one or more first protrusions embedded into the elastically deformable material of the second protrusion .

According to embodiments of the telescopic tube comprising up ^¬ per-mentioned elastically deformable second protrusion, a first stop portion is provided at the inner wall side of the outer tube element, said first stop portion interacting with a second stop portion provided at the outer wall side of the inner tube element, said stop portions providing stop means to limit the angle of rotation by which the tube elements can be rotated rel ative to each other.

The term "essentially" or "approximately" as used in the inven ^¬ tion means deviations from the exact value by +/- 10%, prefera ^¬ bly by +/- 5% and/or deviations in the form of changes that are insignificant for the function.

BRIEF DESCRIPTION OF THE DRAWINGS

The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, which :

Fig. 1 shows an example sectional view of a telescopic tube;

Fig. 2 shows the free ends of an inner and an outer tube el ^¬ ement in an unlocked state;

Fig. 3 shows the free ends of an inner and an outer tube el ^¬ ement in a locked state;

Fig. 4 shows a front-side view of an inner and an outer tube element in an unlocked state;

Fig. 5 shows a front-side view of an inner and an outer tube element in a locked state;

Fig. 6a, 6b shows a top view of the free ends of the tube ele ^¬ ments comprising a lock mechanism including a spring in the unlocked/locked state;

Fig. 7a, 7b shows a top view of the free ends of the tube ele ^¬ ments comprising a self-cleaning mechanism with a slanted edge in order to remove dust;

Fig. 8 shows a spraying apparatus comprising a telescopic tube in an extended state; and

Fig. 9 shows a spraying apparatus comprising a telescopic tube with tube elements inserted into each other. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will now be described more fully with ref- erence to the accompanying drawings, in which example embodi ^¬ ments are shown. However, this invention should not be construed as limited to the embodiments set forth herein. Throughout the following description similar reference numerals have been used to denote similar elements, parts, items or features, when ap- plicable.

Fig. 1 shows a telescopic tube 1 according to an embodiment. The telescopic tube 1 comprises at least two, according to the pre ^¬ sent embodiment three tube elements, namely at least an outer tube element 10 and an inner tube element 20. The outer tube el ^¬ ement 10 comprises an inner diameter which is adapted to the outer diameter of the inner tube element 20 in order to enable a telescopic movement of the inner tube element 20 with respect to the outer tube element 10.

More in detail, the outer tube element 10 comprises a pipe- shaped first tube portion 10.1 with a circular aperture. At the free end, the outer tube element 10 comprises a second tube por ^¬ tion 10.2. At the inner wall side of the second tube portion 10.2 multiple first protrusions 13 are provided. Said first pro ^¬ trusions 13 are circumferentially distributed along the inner circumference of said second tube portion 10.2. Between two con ^¬ secutive first protrusions 13 (consecutive in the circumferen ^¬ tial direction) , a gap 15 is provided. Said gap 15 is dimen- sioned such that a second protrusion 22 provided at the outer wall side of the inner tube element 20 can pass through said gap 15 in order to adapt the length of the telescopic tube 1.

The inner tube element 20 comprises a tube wall with a circular cross shape, wherein at the outer wall side multiple second pro- trusions 22 are provided. Said second protrusions 22 are circum- ferentially distributed along the outer circumference of said inner tube element 20 similar to the gaps 15 provided at the outer tube element 10 in order to fit into said gaps 15. Said second protrusions 22 (in the current embodiment comprising a plurality of webs) comprise a longitudinal shape and extends along the whole or essentially the whole tube element 20. There may be no second protrusions 22 provided in a front portion of the tube element 20 in order to simplify inserting the inner tube element 20 in the outer tube element 10.

At the rear end of the inner tube element 20 a ring-shaped stop portion 25 is provided which radially protrudes from the outer wall side of the inner tube element 20. Said ring-shaped stop portion 25 is adapted to the inner diameter of the outer tube element 10 such that the stop portion 25 may pass through the aperture provided in the first tube portion 10.1 and is blocked by the first protrusions 13 in the area of the second tube por ^¬ tion 10.2.

Furthermore, snap-in-hooks 16 may be provided at least at the outer tube element 10, said snap-in-hooks being adapted to pre ^¬ vent a drop-out of the inner tube element 20 to the rear side. In addition, one or more sealing members may be provided between the inner and outer tube element 10, 20 in order to avoid pene ^¬ tration of dirt in the space between the inner and outer tube elements 10, 20.

As shown in Fig. 2 and Fig. 3, the first and second protrusions 13, 22 comprise a textured shape. Specifically, the first pro ^¬ trusion provided at the inner wall side of the outer tube ele ^¬ ment 10 comprises at least one, preferably multiple grooves 12 or recesses. Said grooves 12 or recesses are oriented in a di ^¬ rection perpendicular to the axial direction of the outer tube element 10. More in detail, the grooves 12 or recesses are cir- cumferentially oriented with respect to the axial direction of the outer tube element 10.

The grooves 12 or recesses comprise a location-dependent depth, wherein the depth decreases from a first groove end 12.1 to a second groove end 12.2. In other words, each groove 12 comprise a groove opening at a side edge of the first protrusion 13 (first groove end) in direct proximity to said gap 15, wherein the depth of the groove or recess decreases with increasing grove length, respectively, with increasing distance to said gap 15. In yet other words, the grooves 12 have a tapered shape. The grooves 12 provided in the first protrusion 12 are parallel to each other and comprise a comb-like shape. Preferably, the lon ^¬ gitudinal direction of the grooves may be perpendicular to the axial direction of the outer tube element.

In order to provide a form-fit between the grooves provided in the first protrusion 13 and the second protrusion 22, said sec ^¬ ond protrusion 22 is inversely shaped to the at least one groove 12 within the first protrusion 13. Preferably, the second pro ^¬ trusion 22 is formed by a plurality of webs 24, in the following also called ribs. Said webs 24 may be parallel with respect to each other wherein the webs 24 are orientated perpendicular to the longitudinal axis of the inner tube element 20. Preferably, the distance between two consecutive webs 24 is egual to the distance of two consecutive grooves 12 or recesses. Thereby, when rotating the inner tube element 20 with respect to the out ^¬ er tube element 10, each groove 12 provided in the first protru ^¬ sion 13 receives one web 24 provided at the second protrusion 22 thereby blocking the telescopic function of the telescopic tube 1.

In order to achieve a clamping between the inner tube element 20 and the outer tube element 10, the second protrusion 22, specif- ically the webs 24 building the second protrusion 22 have a ta- pered shape. Specifically, the height of the webs 24 is increas ^¬ ing from a first end to a second end of the respective web 24. In other words, the upper surface of the web is eccentric with respect to the rotation axis RA around which the inner tube ele- ment 20 is rotatable when inserted in the outer tube element 10. The tapered shape of the webs 24 may correspond to the tapered shape of the grooves 12 or rips in order to achieve a clamping effect along the whole or essentially the whole web 24, respec ^¬ tively, groove 12. So, the shape of the first clamping surface 11 provided within the groove 12 corresponds to the shape of the second clamping surface 21 in order to achieve a form-fitting connection between said clamping surfaces over a large area.

In order to customize the length of the telescopic tube 1, the tube elements 10, 20 of the telescopic tube 1 has to be twisted such that the clamping function is deactivated and the webs 24 are not engaged with the grooves 12. In other words, the inner tube element 20 has to be twisted such that the at least one first protrusion 13 is located within the at least one gap 15 (see Fig. 2 and 4) . In said twisting position, the inner tube element 20 can be moved with respect to the outer tube element 10 and the length of the telescopic tube 1 can be chosen as de ^¬ sired by the user. After customizing the length of the telescop ^¬ ic tube 1, the tube elements may be twisted against each other such that the webs 24 are inserted into the grooves 12 thereby fixing the length by a form-fit engagement of the webs 24 into the grooves 12 and the clamping function between the first and second clamping surfaces 11, 21. The twisting angle of the first and second tube elements 10, 20 may be in the range between 30° and 60°, preferably in the range between 40° and 50°, most pref ^¬ erably 45°.

In order to enable a technically simple and intuitive handling of the telescopic tube 1, at least one first stop portion 14 is provided at the inner wall surface of the outer tube element 10. Said first stop portion 14 may be adapted to interact with the second protrusion 22 of the inner tube element 20 in order to delimit the twisting angle of the inner tube element 20 with re ^¬ spect to the outer tube element 10. There may be multiple first stop portions 14 at the inner wall side of the outer tube ele ^¬ ment 10 wherein each first stop portion 14 is correlated with a first protrusion 13 provided at said inner wall side of the out ^¬ er tube element 10. Said first stop portion 14 may form an inte ^¬ gral part of a first protrusion 13 or may be formed by a sepa- rate protrusion. Said first stop portion 14 may have opposite edges or sides, wherein a first edge or side of said first stop portion 14 may border one of the gaps 15 provided at the inner wall side of the outer tube element 10 and a second edge or side of said first stop portion 14 may delimit the grooves 12 provid- ed in the first protrusion 13. According to the present embodi ^¬ ment, the first protrusion 13 comprises a first and a second protrusion portion 13.1, 13.2, wherein the first protrusion portion 13.1 comprises the at least one groove 12 including the first clamping surface 11 and the second protrusion portion 13.2 forms said first stop portion 14. In other words, the first stop portion 14 is an integral part of the first protrusion 13.

The gaps 15 are formed between the free end of the second pro ^¬ trusion portion 13.2 and the free end of first protrusion por- tion 13.1 of the circumferentially following first protrusion 13.

The first stop portion 14 may interact with at least one second stop portion 23 provided at the outer wall side of the inner tube element 20 such, that said second stop portion 23 adjoins the first stop portion 14 in the unlocked state of the telescop ^¬ ic tube 1 (Fig. 2, Fig. 4) . So, the interaction of first and second stop portion 14 provides a twisting limit which indicates the user that the unlocked state is reached and the length of the telescopic tube can be varied. Furthermore, in case that three or more tube elements form the telescopic tube 1, by twisting the outermost and the innermost tube elements against each other, also the at least one further tube element which is arranged between the outermost and the innermost tube element can be also transferred from the locked state to the unlocked state by means of said first stop portion 14. The second stop portion 23 may be provided by the free ends of the webs 24.

In case that the telescopic tube 1 comprises three or more tube elements, the intermediate tube elements (being enclosed at the inner and outer wall side by further tube elements) comprise at least a first clamping surface 11 at the outer wall side and at least a second clamping surface 21 at the inner wall side. Fig. 6a and Fig. 6b show a preferred embodiment wherein between the first protrusion 13 (provided at the inner wall surface of the outer tube element 10) and the second protrusion 22 (provid ^¬ ed at the outer wall surface of the inner tube element 20) a spring 30 is arranged. Said spring 30 may be, for example a re- versibly deformable spring element wherein a first end of said spring element braces against a lateral surface of the first protrusion 13 and a second end of said spring element braces against a lateral surface of the first protrusion 22. For exam ^¬ ple, the spring 30 may be a leg spring, preferably a plastic spring. More in detail, the spring 30 comprises two spring por ^¬ tions at its free ends wherein said free ends are coupled by means of a flexible, reversibly deformable middle portion. A first free end of the spring 30 rests against the second protru ^¬ sion portion 13.2 forming at least partially the first stop por- tion 14 and the second free end of the spring 30 rests against one or more free ends of the webs 24.

By means of said spring 30, without applying external force to the telescopic tube 1, the telescopic tube 1 is maintained in the locked state, i.e. by means of the spring force of spring 30, the outer tube element 10 is kept in a twisting state with respect to the inner tube element 20 such that the webs 24 of the inner tube element 20 are at least partially inserted into the grooves 12 of the outer tube element 10. Thereby, an unde- sired, uncontrollable extension of length of the telescopic tube in case of high water or air pressure provided within the tele ^¬ scopic tube 1 is avoided.

Preferably, the first stop portion 14 comprises a slanted edge 13.3, wherein the angle a between the slanted edge and the lon ^¬ gitudinal axis of the first tube element is in the range between 30° and 60°, preferably between 40° and 50°, most preferably about 45° and wherein the angle a opens towards the free end of the tube element adjacent to the slanted edge 13.3. A first spring portion may rest against said slanted edge 13.3.

As shown in Fig. 7a and Fig. 7b, the slanted edge 13.3 enables a self-cleaning of the lock mechanism of the telescopic tube 1. In case that dirt enters into the lock mechanism between the free ends of the webs 24 and the first stop portion 14 (Fig. 7b), said dirt may block the twisting of the tube elements in order to unlock the telescopic tube 1. By means of the slanted edge 13.3, dirt located between the free ends of the webs 24 and the slanted edge 13.3 is pushed outwardly, thereby self-cleaning the orifice formed between the free ends of the webs 24 and the slanted edge 13.3.

According to an embodiment, the telescopic tube 1 may be used as an integral part of a spraying apparatus 50 for providing liq- uid, specifically water to water receiving objects, for example, flowers or plants. Such spraying apparatus 50 is shown in Fig. 8 and 9. The telescopic tube 1 may be arranged between a grip por ^¬ tion 51 and a spray head 52 forming the liquid outlet of the spraying apparatus 50. According to a first embodiment, the liq- uid is guided within a pipe included in the interior of the tel- escopic tube. Said pipe may be a bellows 31 which is length- extendible due to its accordion-shaped wall. Due to the bellows 31, a liquid-tight and frost-proof guiding of liquid through the telescopic tube 1 is achieved. Furthermore, the spray head 52 may be directly connected to said bellows 31 wherein due to said bellows 31 a swivel joint (located between the telescopic tube 1 and the spray head 52) is achieved without extra liquid sealing.

According to another embodiment, the liquid can be guided di- rectly through the interior of said telescopic tube 1 wherein the tube elements 10, 20 are sealed to each other by sealing means, e.g. sealing elements, for example lip seals, O-rings etc . The spraying apparatus 50 may be a handheld device, e.g. a spray gun, for providing liquid, specifically water to water receiving objects, for example, flowers or plants. The spraying apparatus 50 comprises a housing with a grip portion 51 for manually hold ^¬ ing the spraying apparatus 50. The spraying apparatus 50 may further comprise activation means 53, for example a button, said activation means 53 being coupled with a valve (not shown) for enabling/disabling or controlling a liquid flow through the spraying apparatus 50. Preferably, the tube elements including the protrusions forming the clamping surfaces may be integrally formed (one-piece tube elements) . The tube elements may be formed by injection molding or the like. The tube elements may be made of plastics, cast iron or metal .

According to the upper-mentioned embodiments, it has been as ^¬ sumed that the second protrusion 22 provided at the inner tube element 20 is integrally formed at the outer surface of the in ^¬ ner tube element 20, is made of a rigid material and comprises a plurality of webs 24 which are received by corresponding grooves 12 provided at the outer tube element. According to another em ^¬ bodiment, the second protrusion 22 may be formed by a layer of elastic material. For example, said elastic material may be a elastomer, specifically an elastic polymer. Said second protru- sion 22 may not comprise any grooves or webs. In other words, the second protrusion 22 may comprise an non-contoured surface. Apart from that, the second protrusion 22 may comprise a shape as disclosed in the context of the above-described embodiments. Specifically, the second protrusion end 22.2 of the second pro- trusion 22 may form a stop portion, several second protrusions 22 may be arranged at the outer circumference of the inner tube element 20 and the second protrusion ( s ) 22 may extend in paral ^¬ lel to the longitudinal axis of the inner tube 20. In addition, the second protrusion 22 may comprise a tapered shape, specifi- cally, the thickness of the second protrusion 22 may increase from the first protrusion end 22.1 to the second protrusion end 22.2. The outer tube element 10 of the telescopic tube may be configured according to the upper-mentioned embodiments. The clamping between the outer tube element 10 and the inner tube element 20 is obtained by rotating the tube elements 10, 20 against each other. Due to said rotation, webs or protrusions provided at the inner surface of the outer tube element 10 may be pushed into the elastic material of the second protrusion 22. In other words, said webs or protrusions may deform the second protrusion 22 thereby causing a form-fit between outer tube element 10 and the inner tube element 20. Due to said form-fit, an interlocking between the outer tube element 10 and the inner tube element 20 is obtained and the telescopic function of the telescopic tube 1 is disabled.

It should be noted that the description and drawings merely il ^¬ lustrate the principles of the proposed methods and systems. Those skilled in the art will be able to implement various ar- rangements that, although not explicitly described or shown herein, embody the principles of the invention.

List of reference numerals

1 telescopic tube

10 outer tube element

10.1 first tube portion

10.2 second tube portion

11 first clamping surface

12 groove

12.1 first groove end

12.2 second groove end

13 first protrusion

13.1 first protrusion portion

13.2 second protrusion portion

13.3 slanted edge

14 first stop portion

15 gap

16 snap-in-hook

20 inner tube element

21 second clamping surface 22 second protrusion

22.1 first protrusion end

22.2 second protrusion end 23 second stop portion

24 web

25 stop portion

30 spring

31 bellows

50 spraying apparatus

51 grip portion

52 spray head

53 activation means

RA rotation axis