DE202019103380U1 - Corrugated pipe made of polymer material - Google Patents

Abstract

Hydraulic tube (1) made of polymer material for a domestic appliance, wherein the tube (1) has at least one corrugated pipe section (A1, B, C, A2) which extends circumferentially about a main axis (X), wherein the corrugated pipe section (A1, B, C, A2) an alternating series of annular ridges (10) and annular recesses (12) extending in respective planes perpendicular to the major axis (X) and side walls (14), the adjacent ridges (10) and recesses (12) of these alternating ones String comprising, characterized in that it comprises a first stiffening element (20; 120) between two adjacent elevations (10) of the annular elevations (10) and a second stiffening element (22; 122) between the two adjacent elevations (10) wherein a reference plane (RP) perpendicular to the major axis (X) intersects the first stiffener (20; 120) and the second stiffener (22; 122), the first stiffener (20; 120) and the second stiffener selement (22; 122) are arranged such that they form in the reference plane (RP) an angle between 90 ° and 270 ° with respect to the main axis (X).

Description

FIELD OF THE INVENTION

The present invention relates to the field of execution of pipes for use in the execution of the hydraulic circuit of household appliances, such as washing machines, dishwashers and dryers. In particular, the present invention relates to a hydraulic corrugated tube made of polymeric material.

STATE OF THE ART

In the field of household appliances such as washing machines, clothes dryers and dishwashers, the use of pipes for hydraulic connection between two points in hydraulic circuits related to the domestic appliance, for example, the connection of a washing machine or a dishwasher to the external Water supply or to the drain, well known.

A first known type of tube consists of a tubular section of molded rubber which is substantially rigid and provided with a suitable geometry which allows the tube to accept and maintain the desired shape in the space between the two points to be hydraulically connected. The rigid rubber tube guarantees a very accurate path and requires only limited or no use of points for anchoring the tube to the appliance along its path.

The technology that uses molded rubber tubes is expensive and has problems with recyclability.

Another well-known type of pipe used in the domestic appliance sector consists of so-called corrugated pipes. The corrugated tubes are defined by a tubular body of polymeric material whose outer profile is shaped and defined by a series of depressions and ridges connected by lateral connecting portions.

This solution has lower manufacturing costs compared to rubber tubes and is advantageously recyclable.

The molded shape of the outer profile of the pipe, together with the material of which the pipe is made, gives the pipe good flexibility, facilitating the connection of its ends to the points to be hydraulically connected. In contrast, this flexibility leads to the inability of the tube to assume a single and accurate three-dimensional configuration, that is, after the ends of the tube are connected, the path taken by the tube itself is ambiguous. This requires the use of various points for anchoring the pipe to the household appliance, for example to its housing, preferably by means of plastic clips or clamps. This results in an increase in installation times and / or costs and the need for additional components compared to the rubber tube solution.

It is therefore an object of the present invention to overcome the disadvantages of the prior art at least partially.

In particular, it is an object of the present invention to provide a corrugated tube that facilitates its positioning and / or retention in position in space as compared to the corrugated tubes of the prior art.

Another object of the present invention is to provide a corrugated tube which simplifies the installation operations.

Another object of the present invention is to provide a corrugated tube which allows to reduce the components required for its installation.

Another object of the present invention is to provide a corrugated pipe which allows to reduce the times and / or costs required for its installation.

SUMMARY

The present invention is based on general considerations for performing a corrugated tube with controlled flexibility.

In a first aspect, therefore, the present invention relates to a polymeric material hydraulic tube for household appliances, the tube having at least one corrugated tube circumferentially extending about a major axis, the corrugated tube having an alternating series of annular ridges and annular depressions perpendicular to respective planes the main axis, and side walls connecting adjacent peaks and valleys of this alternating sequence comprises, wherein the tube comprises a first stiffening element between two adjacent elevations of the annular elevations and a second stiffening element between the two adjacent elevations, wherein a reference plane perpendicular to the main axis intersects the first stiffening element and the second stiffening element, wherein the first stiffening element and the second stiffening element are arranged such that they form in the reference plane an angle between 90 ° and 270 ° relative to the main axis.

The invention preferably relates to a hydraulic pipe made of polymeric material for household appliances, the pipe having at least one corrugated pipe section extending circumferentially about a major axis, the corrugated pipe section having an alternating series of annular ridges and annular recesses perpendicular to the main axis in respective planes, and Side walls connecting adjacent ridges and valleys of this alternating sequence, wherein the tube comprises a first stiffening element between two adjacent elevations of the annular elevations and a second stiffening element between the two adjacent elevations, wherein a reference plane which is perpendicular to the main axis, the first stiffening element and the second stiffening element intersects, wherein the first stiffening element and the second stiffening element are arranged such that they in the reference plane at an angle between 90 ° and 270 ° relative to the Form major axis, and such that they make the at least one corrugated tube piece about an axis of rotation parallel or belonging to the reference plane and perpendicular to the main axis flexible.

In a preferred embodiment, the axis of rotation passes through the first stiffening element and the second stiffening element.

According to a preferred embodiment of the invention, the first stiffening element and the second stiffening element are arranged in the reference plane such that they form an angle of 180 ° with respect to the main axis.

Preferably, the first stiffening element and the second stiffening element are arranged in the reference plane such that they form an angle of 180 ° with respect to the main axis, and such that the at least one corrugated tube piece about an axis of rotation parallel or belonging to the reference plane and perpendicular to the Make main axis flexible.

Even more preferably, the first stiffening element and the second stiffening element are arranged in the reference plane so as to form an angle of 180 ° with respect to the major axis, and such that they surround the at least one corrugated pipe section about an axis of rotation passing through the first stiffening element and the first stiffening element second stiffening element passes through, make flexible.

In a preferred embodiment, the tube in the corrugated pipe section does not comprise any further stiffening elements between the two adjacent elevations other than the first stiffening element and the second stiffening element.

According to a preferred embodiment of the invention, the tube comprises three or more stiffening elements between two adjacent elevations of the annular elevations, wherein a second reference plane perpendicular to the main axis intersects the three or more stiffening elements, the three or more stiffening elements being uniform in the second reference plane about the major axis are arranged distributed.

Preferably, the tube comprises three or more stiffening elements between two adjacent elevations of the annular elevations, wherein a second reference plane perpendicular to the main axis intersects the three or more stiffening elements, the three or more stiffening elements being uniformly distributed in the second reference plane about the major axis, and such that they make the at least one corrugated tube piece stiff relative to the second reference plane.

In a preferred embodiment, the tube comprises four stiffening elements between two adjacent elevations of the annular elevations, wherein a second reference plane perpendicular to the main axis intersects the four stiffening elements, the four stiffening elements being uniformly distributed in the second reference plane about the major axis.

Preferably, each pair of adjacent ridges of a plurality of ridges of the series comprises the first stiffener and the second stiffener, the first stiffeners of the plurality of ridges aligned along a same direction along the corrugated pipe and the second stiffeners of the plurality of ridges along one the same direction along the corrugated tube piece are aligned.

In a preferred embodiment, the first stiffening element and / or the second stiffening element is manufactured in one piece with the two adjacent elevations.

Preferably, the tube is made of polypropylene.

According to a preferred embodiment of the invention, the corrugated tube piece extends in a cylindrically around the main axis.

Preferably, the annular ridges comprise a linear piece in a direction parallel to the major axis with the side walls is connected, and / or the annular recesses comprise a curved piece, which is connected to the side walls.

list of figures

• - 1 ein Rohr gemäß einer bevorzugten Ausführungsform der vorliegenden Erfindung in axonometrischer Ansicht zeigt;
• - 2 eine Draufsicht von unten des Rohrs von 1 zeigt;
• - 3 die Schnittansicht entlang der Schnittlinie III°-III° von 2 zeigt;
• - 4 ein erstes vergrößertes Detail von 3 zeigt;
• - 4A ein vergrößertes Detail von 4 zeigt;
• - 5 ein zweites vergrößertes Detail von 3 zeigt;
• - 5A ein vergrößertes Detail von 4 zeigt;
• - 6 ein drittes vergrößertes Detail von 3 zeigt;
• - 7 die Schnittansicht entlang der Schnittlinie VII°-VII° von 2 zeigt;
• - 8 die Schnittansicht entlang der Schnittlinie VIII°-VIII° von 2 zeigt;
• - 9 die Schnittansicht entlang der Schnittlinie IX°-IX° von 2 zeigt;
• - 10 die Schnittansicht entlang der Schnittlinie X°-X° von 2 zeigt;
• - 11 das Rohr von 1 in einer möglichen Betriebskonfiguration in schematischer axonometrischer Ansicht zeigt;
• - 12 eine Ausführungsvariante von 9 zeigt;
• - 13 eine Ausführungsvariante von 7 zeigt;
• - 14 eine andere Ausführungsvariante von 7 zeigt.

For a better understanding of the features and advantages of the invention, non-limiting examples of a practical embodiment will now be described with reference to the accompanying drawings, in which:

• - 1 a tube according to a preferred embodiment of the present invention in axonometric view shows;
• - 2 a top view from below of the pipe of 1 shows;
• - 3 the sectional view along the section line III ° -III ° from 2 shows;
• - 4 a first enlarged detail of 3 shows;
• - 4A an enlarged detail of 4 shows;
• - 5 a second enlarged detail of 3 shows;
• - 5A an enlarged detail of 4 shows;
• - 6 a third enlarged detail of 3 shows;
• - 7 the sectional view along the section line VII -VII ° ° from 2 shows;
• - 8th the sectional view along the section line VIII-VIII ° ° from 2 shows;
• - 9 the sectional view along the section line IX-IX ° ° from 2 shows;
• - 10 the sectional view along the section line X ° -X ° from 2 shows;
• - 11 the pipe of 1 in a possible operating configuration in schematic axonometric view;
• - 12 a variant of 9 shows;
• - 13 a variant of 7 shows;
• - 14 another embodiment of 7 shows.

DETAILED DESCRIPTION OF THE INVENTION

Although the present invention will be described below with reference to the preferred embodiments thereof shown in the drawings, the present invention is not limited to the embodiments described below and illustrated in the drawings. Rather, the described and illustrated embodiments illustrate some aspects of the present invention, the scope of which is defined by the claims.

The present invention has proved to be particularly advantageous with respect to the design of a hydraulic pipe which is used for internal connections of the hydraulics of washing machines and tumble dryers.

It should be understood, however, that the present invention is not limited to the practice of a tube intended for that purpose. Rather, the present invention finds practical application in all cases, which provide for the use of a hydraulic pipe for the hydraulic connection between two points in hydraulic circuits of a household appliance.

In 1 is a preferred embodiment of a tube 1 , which is the subject of the present invention.

The tube shown in the figure 1 is preferably and advantageously used for the hydraulic connection between two points in hydraulic circuits of a household appliance.

This is the tube 1 preferably at its ends with end parts 2 . 4 provided for the execution of the connections.

The pipe 1 is preferably made of polymeric material, more preferably of a thermoplastic material such as polypropylene copolymer (PPC).

Preferably, the tube 1 manufactured by a Wellformgebungsprozesses. Preferably, the end parts 2 . 4 also made of thermoplastic material, for example vulcanized thermoplastic elastomers (TPV). Preferably, the connections 2 . 4 with the ends of the pipe 1 connected by over-molding.

The pipe 1 is advantageously completely recyclable.

In embodiments, the polymeric material of the tube and / or the material of the end portions may be of a different type, such as polypropylene homopolymer or random or PE-RT rather than polyamides.

The pipe 1 preferably has a cylindrical tubular shape which extends circumferentially about a major axis X.

In embodiments, however, the tube may have a portion that is not exclusively circular but any polygonal and / or mixed-line shape circumferentially about the major axis X is closed.

The pipe 1 According to the embodiment shown in the figures, preferably comprises a plurality of adjacent corrugated tube pieces, which in the figures with A1 . B . C and A2 are designated.

As a corrugated tube piece is to be understood a piece comprising an alternating sequence of annular elevations 10 and annular recesses 12 , which are in respective planes perpendicular to the main axis X run, and sidewalls 14 , the neighboring increases 10 and depressions 12 connect the alternate sequence, as in 4A shown in detail.

In the preferred embodiment of the present invention illustrated and described herein, the annular ridges comprise 10 preferably a linear piece with the side walls 14 connected is. The linear piece preferably extends along a direction parallel to the major axis X ,

The annular depressions 12 Preferably, they comprise a curved piece, more preferably a peripheral portion which is integral with the side walls 14 connected is.

In embodiments, however, the annular ridges and / or the annular recesses may have a different shape from that described here.

According to a preferred aspect of the present invention comprises one of the corrugated pipe sections, in the present case, the second corrugated pipe section B or the third corrugated pipe section C , first stiffening elements 20 between adjacent elevations of the annular elevations 10 and second stiffening elements 22 between the adjacent elevations (more visible in the 5 and 5A) ,

In the preferred embodiment of the present invention illustrated and described herein, all annular adjacent ridges include 10 the relevant pieces, that is the second corrugated pipe section B and the third corrugated pipe section C , a respective first stiffening element 20 and a second stiffening element 22 ,

Preferably, the first stiffening elements 20 from the plurality of adjacent peaks along a same direction along the second corrugated pipe section B aligned and the second stiffening elements 22 are of the plurality of adjacent peaks along a same direction along the third corrugated pipe section C aligned.

According to a preferred aspect of the present invention, the first stiffening element 20 and the second stiffening element 22 arranged such that it is preferably an angle Z1 of 180 ° relative to the main axis X in a reference plane RP form. The reference plane RP consists of one level RP perpendicular to the main axis X is that the first stiffening element 20 and the second stiffening element 22 cuts. The mutual arrangement between each other between the first stiffening element 20 and second stiffening element 22 is in the 8th and 9 where the reference plane RP corresponds to the leaf level, shown in detail.

The first stiffening element 20 and the second stiffening element 22 , in the 8th are shown, refer to the second corrugated pipe section B and the first stiffening element 20 and the second stiffening element 22 , in the 9 on the other hand, reference is made to the third corrugated tube C.

In the preferred embodiment of the present invention illustrated and described herein, the angle is Z1 that of the first stiffening element 20 and the second stiffening element 22 is formed, preferably as stated above, that is equal to 180 °.

In embodiments, this angle may preferably assume a value between 90 ° and 270 °.

Advantageously, the stiffening elements allow it 20 and 22 According to the invention, the bending direction of the corrugated tube piece concerned B . C to control. In particular, as it is for example in 1 shown, make the second corrugated tube piece B associated first stiffening elements 20 and second stiffening elements 22 the piece itself about a rotation axis T1 flexible. In other words, the second corrugated piece B around the axis of rotation T1 that is, according to a given direction, be curved.

In the figure, the rotation axis T1 shown as belonging to the reference plane RP. More general make the first stiffening elements 20 and the second stiffening elements 22 the piece itself about a rotation axis T1 parallel or associated with the reference plane RP and perpendicular to the major axis X flexible. Even more preferably, the axis of rotation is running T1 through the first stiffening element 20 and the second stiffening element 22 therethrough.

Analog make the third corrugated pipe section C associated first stiffening elements 20 and second stiffening elements 22 the piece itself about a rotation axis T2 flexible. The third corrugated pipe section C can thus turn the axis of rotation T2 be curved.

In the figure, the rotation axis T2 as belonging to the reference plane RP shown. More general make the first stiffening elements 20 and the second stiffening elements 22 the piece itself about a rotation axis T2 parallel or associated with the reference plane RP and perpendicular to the major axis X flexible.

Even more preferably, the axis of rotation is running T2 through the first stiffening element 20 and the second stiffening element 22 therethrough.

Further advantageously, the corrugated tube pieces B and C of the pipe 1 in a controlled manner around the respective axes of rotation T1 and T2 be curved to the pipe 1 according to a desired configuration, such as in 11 shown to form spatially. This results in the possibility of the corrugated pieces B and C to arrange in appropriate receptacles, which are provided in the household appliance, for example a washing machine.

For example, the pipe 1 be spatially shaped to adopt a configuration that follows the shape of the rear wall of the washing machine, where the pipe is placed, or to avoid any obstacles that exist between the hydraulic connection points to be connected. The pipe 1 according to the invention therefore facilitates its positioning and / or retention in position between the points to be hydraulically connected, thereby simplifying the installation operations with reduced components, reduced times and / or costs for its installation compared to the prior art.

The pipe 1 allows the use of plastic clips or clamps for anchoring along its way, as it is the case with the known corrugated pipes, the case to reduce or possibly eliminate.

It should be noted that in the preferred embodiment illustrated and described herein, the stiffening elements 20 and 22 the corrugated tube pieces B . C are made in such a position that they respective axes of rotation T1 and T2 which are perpendicular to each other define.

However, it will be appreciated that in embodiments in the various corrugated pipe sections to which they are carried out, the stiffening elements may take on different positions to define respective axes of rotation with angles different from each other and not only perpendicular. In general, therefore, the corrugated pipe pieces may be curved in directions that are different from each other and dependent on the arrangement of the stiffening elements between the elevations and the depressions of the corresponding portions of the piece itself.

Further, while in the preferred embodiment illustrated and described herein only two corrugated pipe pieces B, C are provided with controlled flexibility, the number and / or sequence of such controlled flexibility pieces may vary in design variations and according to the global shape that the pipe after the Should accept installation and / or can be selected.

According to a further preferred aspect of the present invention, one of the corrugated tube pieces, in this case the first corrugated tube piece, comprises A1 or the fourth corrugated pipe section A2 , four stiffening elements 26 between adjacent elevations of the annular elevations 10 ,

In the preferred embodiment of the present invention illustrated and described herein, all annular ridges include 10 the relevant pieces, that is the first corrugated pipe section A1 and the fourth corrugated pipe section A2 , four stiffening elements 26 ,

According to a preferred aspect of the present invention, the stiffening elements 26 arranged so that it is even around the major axis X in a reference plane RP ' are distributed. The reference plane RP ' consists of one level RP perpendicular to the main axis X is that the stiffening elements 26 cuts.

The stiffening elements 26 , in the 7 are shown refer to the first corrugated pipe section A1 , and the stiffening elements 26 , in the 10 are shown, however, refer to the fourth corrugated pipe section A2 ,

In the preferred embodiment of the present invention illustrated and described herein, the stiffening elements are 26 at an angle of 90 ° to each other relative to the main axis X arranged.

Advantageously, the stiffening elements allow it 26 according to the invention, the corrugated tube piece with respect to the reference plane RP ' to make stiff. In particular, such as in 1 shown, make the first corrugated tube piece A1 associated stiffening elements 26 the piece even stiff. Analog make the fourth corrugated pipe section A2 associated stiffening elements 26 the piece itself stiff.

It should be noted that in the preferred embodiment of the present invention illustrated and described herein, only two rigid corrugated tube pieces A1 . A2 available. In embodiments, the number and / or sequence of such rigid pieces may be selected differently and in accordance with the global shape that the pipe should and / or can assume after installation.

In the embodiment herein in relation to the 1 to 11 is illustrated, are the stiffening elements 26 in number 4 in front.

In embodiments, however, the number of stiffening elements may be different, if greater than 3. Exemplary in 13 a detail of an embodiment variant shown, the use of three stiffening elements 226 shows that evenly in the reference plane RP ' around the main axis X , thus arranged at angles of 120 °, distributed.

In the illustrated embodiment, preferably comprises a stiffening element 226 , the upper in the figure, a substantially trapezoidal shape in section and is preferably arranged symmetrically with respect to the radial axis concerned, and the two lower stiffening elements 226 preferably have a shape substantially trapezoidal in section and are preferably arranged asymmetrically with respect to the radial axis concerned. This shape favors the molding operations of the pipe and, in particular, facilitates easy removal of the pipe from the molds when shaping by means of corrugated shaping.

In embodiments, however, the section of the stiffening elements may be different, for example any mixed-line, symmetrical or non-symmetrical shape.

In 14 a detail of another embodiment is shown, showing the use of eight stiffening elements 326 shows that evenly in the reference plane RP ' are arranged distributed around the main axis X, thus at angles of 45 °.

In the illustrated embodiment, four stiffening elements 326 Preferably, a substantially trapezoidal shape in the section and are preferably arranged symmetrically with respect to the radial axis concerned, and four stiffening elements 326 preferably have a shape substantially trapezoidal in section and are preferably arranged asymmetrically with respect to the radial axis concerned. This shape favors the molding operations of the pipe and, in particular, facilitates easy removal of the pipe from the molds when shaping by means of corrugated shaping.

In alternative embodiments, however, the section of the stiffening elements can be different, for example any mixed-line, symmetrical or non-symmetrical shape.

With reference to 12 a detail of an embodiment of the invention is shown in which a pair of first stiffening elements 120 between adjacent elevations of the annular elevations 10 and a pair of second stiffeners 122 is provided between the adjacent elevations.

Advantageously, the stiffening elements allow it 120 and 122 According to this embodiment, the bending direction of the pipe section about an intermediate rotational axis T3 to control.

The stiffening elements 120 . 122 make the relevant piece of pipe around this axis of rotation T3 flexible, which is preferably parallel or associated with the reference plane and perpendicular to the main axis.

In the illustrated embodiment, the stiffening elements 120 . 122 Preferably, a substantially trapezoidal shape on average and are preferably arranged asymmetrically relative to the radial axis concerned. This shape favors the molding operations of the pipe and, in particular, facilitates easy removal of the pipe from the molds when shaping by means of corrugated shaping.

In alternative embodiments, however, the section of the stiffening elements can be different, for example any mixed-line, symmetrical or non-symmetrical shape.

According to a preferred embodiment of the invention, the stiffening elements 20 . 22 . 26 . 120 . 122 . 226 . 326 in one piece with the respective adjacent elevations 10 made and are more preferably obtained during the Wellformgebungsprozesses.

In embodiments, the stiffening elements may be implemented in various ways, for example by means of over-molding or by joining / gluing appropriately shaped elements arranged between the adjacent elevations.

It has thus been shown by means of the present description that the tube according to the present invention allows to fulfill the given purposes. In particular, the corrugated tube according to the present invention facilitates its installation on the household appliance in comparison to the known corrugated tubes. Advantageously, the stiffening elements allow a corresponding length of corrugated pipe to easily curve about a predetermined direction and at the same time resist or at least counteract the curvature of the same length of pipe about directions other than the predetermined direction just given above. This allows the pipe to be easily installed. In particular, the corrugated tube pieces can be easily arranged in recordings that have multiple flatness variations. On the one hand, the corrugations are characterized on the one hand by an increased flexibility about the predetermined direction and on the other hand are characterized by a good flexural strength about directions that are different from the given direction.

Although the present invention has been previously clarified by the detailed description of some embodiments shown in the drawings, the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, other variants of the described embodiments fall within the scope of the present invention, the scope being defined by the claims.

Claims (14)

Hydraulic tube (1) made of polymer material for a domestic appliance, wherein the tube (1) has at least one corrugated pipe section (A1, B, C, A2) which extends circumferentially about a main axis (X), wherein the corrugated pipe section (A1, B, C, A2) an alternating series of annular ridges (10) and annular recesses (12) extending in respective planes perpendicular to the major axis (X) and side walls (14), the adjacent ridges (10) and recesses (12) of these alternating ones String comprising, characterized in that it comprises a first stiffening element (20; 120) between two adjacent elevations (10) of the annular elevations (10) and a second stiffening element (22; 122) between the two adjacent elevations (10) wherein a reference plane (RP) perpendicular to the major axis (X) intersects the first stiffener (20; 120) and the second stiffener (22; 122), the first stiffener (20; 120) and the second stiffener gselement (22; 122) are arranged such that they form in the reference plane (RP) an angle between 90 ° and 270 ° relative to the main axis (X). Pipe (1) to Claim 1 wherein the first stiffening element (20; 120) and the second stiffening element (22; 122) are arranged in the reference plane (RP) so as to form an angle of 180 ° with respect to the major axis (X). A tube (1) according to any one of the preceding claims, wherein the tube comprises three or more stiffening elements (26; 226; 326) between two adjacent ridges (10) of the annular ridges (10), a second reference plane (RP ') perpendicular to the ridge Major axis (X) intersecting the three or more stiffening elements (26; 226; 326), wherein the three or more stiffening elements (26; 226; 326) are evenly distributed in the second reference plane (RP ') about the major axis (X). Pipe (1) to Claim 3 wherein the tube comprises four stiffeners (26) between two adjacent ridges (10) of the annular ridges (10), a second reference plane (RP ') perpendicular to the major axis (X) intersecting the four ridges (26), the four Stiffening elements (26) are arranged uniformly distributed in the second reference plane (RP ') about the main axis (X). A tube (1) according to any one of the preceding claims, wherein each pair of adjacent ridges (10) of a plurality of ridges (10) of the string comprises the first stiffener (20; 120) and the second stiffener (22; 122), the first stiffeners (20) of the plurality of ridges (10) are aligned along a same direction along the corrugated pipe section (B, C) and the second stiffening elements (22) of the plurality of ridges (10) are aligned along a same direction along the corrugated pipe section (B, B); C) are aligned. Tube (1) according to one of the preceding claims, wherein the first stiffening element (20; 120) and / or the second stiffening element (22; 122) is made in one piece with the two adjacent elevations (10). Pipe (1) according to one of the preceding claims, wherein the pipe (1) is made of polypropylene copolymer. Pipe (1) according to one of the preceding claims, wherein the corrugated pipe section (A1, B, C, A2) extends around the main axis (X) in a cylindrical manner. A tube (1) according to any one of the preceding claims, wherein the annular ridges (10) comprise a linear piece connected in a direction parallel to the major axis (X) and connected to the side walls (14). A tube (1) according to any one of the preceding claims, wherein the annular recesses (12) comprise a curved piece connected to the side walls (14). Pipe (1) according to one of the preceding claims, wherein the corrugated tube piece (B, C) according to a predetermined direction (T1, T2) may be curved so that it can be easily positioned in a receptacle of the household appliance. A pipe (1) according to any one of the preceding claims, wherein the pipe section (B, C) can not be curved in directions other than a predetermined direction (T1, T2) to prevent errors in positioning in a housing of the household appliance. A pipe (1) according to any one of the preceding claims, wherein the pipe (1) comprises a plurality of pipe pieces (B, C) and which pieces may be curved in directions (T1, T2) which depend on the arrangement of the stiffening elements (20, 20) , 120, 22, 122) are different. A pipe (1) according to any one of the preceding claims, wherein each pipe section (B, C) in which the stiffening elements (20, 120, 22, 122) connecting respective ones of the ridges and the recesses are present is not in other directions except may be curved according to a predetermined direction (T1, T2) defined by the position of the stiffening members (20, 120, 22, 122), and wherein for each of the pipe pieces (A1, B, C, A2) the predetermined direction (T1, T2) may be different from that of the other pieces, so that the pipe (1) can be arranged in housings of the household appliance having a different flatness, thereby simultaneously maintaining a bending strength along orthogonal directions to the predetermined direction.

Images