Corrugated tube and wireharness

A corrugated tube made of resin includes outer grooved portions and outer ridged portions which are formed in a circumferential direction when the corrugated tube is seen from the outside. The outer grooved portions and the outer ridged portions continuously alternate in a tube-axial direction. Inner ridged portions and inner grooved portions are formed on an inner surface of the corrugated tube so as to respectively conform to the shapes of the outer grooved portions and the outer ridged portions. A cushioning portion is formed on the inner surface of the corrugated tube, and has hardness softer than that of a covering outer surface of one or multiple conductive paths accommodated in the corrugated tube.

CROSS-REFERENCES TO RELATED APPLICATION(S)

This application is based on and claims priority from Japanese Patent Application Nos. 2015-029685 and 2015-029686 both filed on Feb. 18, 2015, the entire contents of which are incorporated herein by reference.

BACKGROUND

Field of the Invention

The present invention relates to a corrugated tube made of resin including bellows-like grooved portions and bellows-like ridged portions, and to a wireharness including the corrugated tube.

Description of Related Art

A wireharness used for electrical connection is routed in a vehicle such as an automobile. A wireharness which is a bundle of thin electric wires is widely known. In recent years, a wireharness for an electric vehicle or a hybrid electric vehicle, which is formed of thick high-voltage electric wires, has also been known. The wireharness may include an electric-wire protective corrugated tube. The corrugated tube is formed to include bellows-like grooved portions and bellows-like ridged portions such that the bellows-like grooved portions and the bellows-like ridged portions continuously alternate in a tube-axial direction.

A corrugated tube disclosed in JP-A-2011-254614 has a structure in which the corrugated tube is not damaged when a relatively hard electric wire cover strikes an inner surface of the corrugated tube due to transmission of vibration to a wireharness during travelling of a vehicle. The corrugated tube includes two layers, that is, an inner layer and an outer layer. According to the corrugated tube, even if the electric wire cover has hardness higher than that of the corrugated tube, an inner-layer corrugated tube, which is interposed between an outer-layer corrugated tube and the electric wire cover, serves as a cushioning member. As a result, damage to the outer-layer corrugated tube can be prevented.

It is required to provide a corrugated tube which is useful even when an electric wire cover has hardness softer than that of the corrugated tube. In other words, it is required to provide a corrugated tube with a structure in which an electric wire cover is not damaged, and degradation in a quality of the electric wire cover caused by friction or contact between the corrugated tube and the electric wire cover does not occur even when an electric wire vibrates while striking an inner surface of the corrugated tube.

Corrugated tubes with the structures illustrated inFIGS. 4 and 5were examined, as related technology products. The corrugated tubes with the structures illustrated inFIGS. 4 and 5do not correspond to prior art of the present invention.

InFIG. 4, a corrugated tube1includes outer grooved portions2and outer ridged portions3. The multiple outer grooved portions2and multiple outer ridged portions3are formed in such a way as to continuously alternate in a tube-axial direction. Inner ridged portions4and inner grooved portions5are formed in an inner surface of the corrugated tube1so as to respectively conform to shapes of the outer grooved portions2and the outer ridged portions3. A cushioning member8is disposed and formed on the inner surface of the corrugated tube1such that the cushioning member8is interposed between a covering outer surface7of an electric wire (conductive path)6and the inner surface of the corrugated tube1. The cushioning member8is made of a material which is relatively soft and has low frictional resistance. The cushioning member8is formed in such a way as to cover the inner ridged portions4and the inner grooved portions5, and to completely cover the inner grooved portions5.

Since the corrugated tube1has a structure in which the soft cushioning member8having low frictional resistance is interposed between the covering outer surface7of the electric wire6and the corrugated tube1, even if the electric wire6vibrates, it is possible to prevent damage to the covering outer surface7. Degradation in the quality of the covering outer surface7caused by friction or contact therebetween can also be prevented.

In contrast, since the corrugated tube1has the structure in which the inner grooved portions5are completely covered with the cushioning member8, even if the corrugated tube1is to be bent, the cushioning member8is not bent unless being extended or contracted. As a result, the corrugated tube1inFIG. 4has a problem in that the tube's own flexibility is reduced.

InFIG. 5, a corrugated tube11includes outer grooved portions12and outer ridged portions13. The multiple outer grooved portions12and the multiple outer ridged portions13are formed in such a way as to continuously alternate in a tube-axial direction. Inner ridged portions14and inner grooved portions15are formed in an inner surface of the corrugated tube11so as to respectively conform to the shapes of the outer grooved portion12and the outer ridged portion13. A tube18is disposed and formed on the inner surface of the corrugated tube11such that the tube18is interposed between a covering outer surface17of an electric wire (conductive path)16and the inner surface of the corrugated tube11. The tube18is fixedly attached to, and is formed integrally with the inner ridged portions14in such a way that the tube18does not strike the inner ridged portions14. The tube18is relatively flexible, and is formed such that an inner tube surface is smooth.

Since the corrugated tube11has a structure in which the flexible tube18having a smooth inner surface is interposed between the covering outer surface17of the electric wire16and the corrugated tube11, even if the electric wire16vibrates, it is possible to prevent damage to the covering outer surface17. Degradation in the quality of the covering outer surface17caused by friction or contact therebetween can also be prevented.

In contrast, since the corrugated tube11has the structure in which the tube18is fixedly attached to the inner ridged portions14, even if the corrugated tube11is to be bent, the tube18is stiff and is not bent. As a result, in the corrugated tube11inFIG. 5, the tube's own flexibility is reduced.

SUMMARY

One or more embodiments relate to a corrugated tube which does not cause damage to a covering outer surface of a conductive path by vibration, and degradation in a quality of the covering outer surface caused by friction or contact therebetween does not occur. One or more embodiments also relates to a wireharness including the corrugated tube.

DETAILED DESCRIPTION

Embodiments will be described with reference to the accompanying drawings.FIG. 1is a schematic view illustrating an example of the routing of a wireharness including a corrugated tube in embodiments (including a first embodiment and a second embodiment).

Hereinafter, an example, in which the corrugated tube in embodiments is applied to a wireharness routed in a hybrid electric vehicle (may be an electric vehicle, a usual automobile which travels using driving power from an engine, or the like) will be described.

InFIG. 1, reference sign21represents a hybrid electric vehicle. The hybrid electric vehicle21is a vehicle driven by driving power from a combination of two power sources, that is, an engine and a motor. Electrical power is supplied from a battery to the motor via an inverter unit. Reference sign22represents a vehicle frame. An upper side of the vehicle frame22represents a vehicle upperfloor portion23, and a lower side of the vehicle frame22represents a vehicle underfloor portion24.

In the embodiments, a wireharness25is routed on the vehicle underfloor portion24(the routing position is an example, and the wireharness25may be routed on the vehicle upperfloor portion23). The wireharness25is routed in a position where vibration is transmitted to the wireharness25.

The wireharness25includes one or multiple conductive paths26; a corrugated tube27which is made of resin, and accommodates and protects the conductive paths26; and a fixing member28fixing the corrugated tube27to the vehicle underfloor portion24.

As one example, the conductive path26may include a conductor having electrical conductivity, and an insulator having electrical insulating properties, with which the conductor is covered. The conductor may be made of copper, a copper alloy, aluminum, or an aluminum alloy, and has a circular sectional shape. As another example, the conductive path26may include: an insulated wire made up of a conductor having electrical conductivity and an insulator having electrical insulating properties; a braid (shielding member) provided on an outside of the insulated wire; and a sheath with which the braid is covered. In a case where the conductive path26includes the conductor having electrical conductivity, and the insulator having electrical insulating properties for covering the conductor, an outer surface of the insulator corresponds to a “covering outer surface”. In a case where the conductive path26includes: the insulated wire made up of the conductor having electrical conductivity and the insulator having electrical insulating properties; the braid (shielding member) provided on the outside of the insulated wire; and the sheath for covering the braid, an outer surface of the sheath corresponds to the “covering outer surface”.

The conductor may have either a conductor structure in which wire strands are twisted together, or a bar-shaped conductor structure (for example, a conductor structure in which the conductor is a single flat square-shaped core or a single round core, and in this case, an electrical wire also has a bar shape) in which a sectional shape of the conductor is rectangular or circular (round). The insulator made of a resin material having electrical insulting properties is extrusion-molded over an outer surface of the conductor.

The insulator is extrusion-molded over the outer circumferential surface of the conductor with a thermoplastic resin material. The insulator is formed as a covering member which may have a circular sectional shape. The insulator is formed to have a predetermined thickness. Various types of well-known materials can be used as the thermoplastic resin, and for example, the material of the insulator is appropriately selected from high-polymer materials such as polyvinylchloride resin, polyethylene resin, and polypropylene resin.

The braid is an electromagnetic shielding metal component (shielding member counteracting electromagnetic waves), and is formed by weaving together a number of metal wire strands into a cylindrical shape.

The sheath is extrusion-molded on the braid with thermoplastic resin material. The sheath is formed as a covering member. The sheath is formed to have a predetermined thickness. Various types of well-known materials can be used as the thermoplastic resin, and for example, the material of the sheath is appropriately selected from high-polymer materials such as polyvinylchloride resin, polyethylene resin, and polypropylene resin. The sheath may be replaced with a well-known heat shrinkable tube.

The corrugated tube27is formed into a tubular shape having a circular section (the sectional shape is an example, and the corrugated tube27may have an oval sectional shape, an elliptical sectional shape, or the like corresponding to the shape of the conductive path26or the number of conductive paths26). The corrugated tube27is formed into the illustrated shape when seen from an outside, and includes outer grooved portions29and outer ridged portions30in a circumferential direction. The corrugated tube27is formed into the illustrated shape in which the outer grooved portions29and the outer ridged portions30continuously alternate in a tube-axial direction (refer to a central line CL).

In the embodiments, the corrugated tube27is formed not to include a slit in the tube-axial direction (formed into a shape in which the belly of the tube is not split). In other words, the corrugated tube27is formed into a shape capable of preventing an infiltration of external water thereinto.

The outer grooved portions29are formed in valley portions of the corrugated tube27when seen from an outside. The outer ridged portions30are formed in peak portions of the corrugated tube27when seen from the outside. More specifically, each of the outer grooved portions29is formed in a valley-like portion in which a groove having a U-shaped section makes one turn around the tubular axis in the circumferential direction. Each of the outer ridged portions30is formed in a peak-like portion in which a ridge having an inverted cup-shaped section makes one turn around the tubular axis in the circumferential direction. The shape of the each of the outer ridged portion30is not limited to the illustrated shape, and an inverted U-shaped ridged portion may be formed as the outer ridged portion30. The respective sectional shapes of the outer grooved portion29and the outer ridged portion30in the embodiments are exemplarily given.

Inner ridged portions31and inner grooved portions32are formed in an inner surface of the corrugated tube27so as to respectively conform to the shapes of the outer grooved portions29and the outer ridged portions30. As illustrated, each of the inner ridged portions31is formed into a ridged shape when the corrugated tube27is seen from the inside. The inner ridged portions31are disposed at axial positions of the outer grooved portion29. Each of the inner grooved portions32is formed into a grooved shape when the corrugated tube27is seen from the inside. The inner grooved portions32are disposed at axial positions of the outer ridged portions30. One or more cushioning portions33are formed on the inner surface of the corrugated tube27.

As illustrated inFIG. 2, in the first embodiment, the cushioning portions33are formed only in apex portions of the inner ridged portions31on the inner surface of the corrugated tube27. Each of the cushioning portions33having substantially uniform thickness is formed to make one turn in the circumferential direction (that is, the each of the cushioning portions33is formed into an annular shape). When the portion of reference sign34in each of the cushioning portions33represents a contact surface which can be brought into contact with an insulator outer surface (covering outer surface) of the conductive path26or a sheath outer surface (covering outer surface), the contact surface34of the cushioning portion33is smoothly rounded. Since the cushioning portions33are formed only in the apex portions of the respective inner ridged portions31, the original shape of the respective inner grooved portions32are maintained in the cushioning portions33.

The each of the cushioning portion33is formed as a portion having hardness softer than that of the covering outer surface of the conductive path26. Any one of the following materials can be used as the specific material of the cushioning portions33: polyolefin resin; polyamide resin; vinyl chloride resin; silicone resin; fluorine resin; polycarbonate resin; polyimide resin; polyester resin; polyurethane resin; and the like. A foaming agent may also be added to the material. The each of the cushioning portion33preferably has a thickness of 1 μm to 500 μm (the thickness of the cushioning portion33is exaggeratedly illustrated inFIG. 2).

The cushioning portions33are formed by extrusion-molding the aforementioned material, or applying the aforementioned material to the inner ridged portion31(the manufacturing method is not limited to a specific method).

For a little more detailed description of the application of the material, first, a columnar or cylindrical bar is prepared, and subsequently, the material of the cushioning portions33is attached to an outer surface of the bar except for a handle of the bar. Subsequently, the material is applied to only the apex portions by inserting the bar into the corrugated tube27, and rotating the bar while the material is in contact with the apex portions of the inner ridged portions31. Thereafter, the material is hardened, and as a result, the formation of the cushioning portions33is complete.

According to the corrugated tube27of the first embodiment, since the soft cushioning portions33are formed only in the apex portions of the inner ridged portions31, the original shape of the inner grooved portions32can be maintained. That is, since the inner grooved portions32are not coated with the cushioning portion33, the corrugated tube27can be easily bent. Accordingly, the corrugated tube27is capable of maintaining its own flexibility.

According to the corrugated tube27of the first embodiment, since the each of the contact surfaces34of the cushioning portions33is smoothly rounded, an occurrence of degradation in a quality of the covering outer surface caused by friction or contact between the covering outer surface of the conductive path26and the each of the contact surfaces34can be prevented, or degradation in the quality of the covering outer surface can be considerably reduced.

As a result, according to the first embodiment, it is possible to provide the corrugated tube27in which the covering outer surface of the conductive path26is not damaged during vibration of the conductive path26, and the occurrence of degradation in the quality of the covering outer surface caused by friction or contact between the corrugated tube27and the covering outer surface is prevented, and to provide the wireharness25including the corrugated tube27.

The second embodiment will be described with reference toFIG. 3. The cushioning portion33in the second embodiment is integrally formed along the inner surface of the corrugated tube27. When a portion of reference sign34represents a contact surface which can be brought into contact with the insulator outer surface (covering outer surface) of the conductive path26or the sheath outer surface (covering outer surface), the cushioning portion33having a substantially uniform thickness is integrally formed along the corrugated tube27in such a way that the contact surface34becomes a surface conforming to the ridged shapes of the inner ridged portions31and the grooved shapes of the inner grooved portions32(the thickness is only an example, and the cushioning portion33may have a thicker thickness at the positions of the inner ridged portions31, and a thinner thickness at the positions of the inner grooved portions32).

Since the contact surface34is formed to conform to the ridged shapes of the inner ridged portions31and the grooved shapes of the inner grooved portions32, the cushioning portion33includes extendable and contractible grooved portions35which make one turn in the circumferential direction. That is, the cushioning portion33is formed into a shape in which the inner grooved portions32are not filled with the cushioning portion33. The contact surface34of the cushioning portion33is smoothly formed at least at the positions of the inner ridged portions31. In the second embodiment, the contact surface34is smoothly rounded at the positions of the inner ridged portions31.

The cushioning portion33is formed to have hardness softer than that of the covering outer surface of the conductive path26. Any one of the following materials may be used as the specific material of the cushioning portion33: polyolefin resin; polyamide resin; vinyl chloride resin; silicone resin; fluorine resin; polycarbonate resin; polyimide resin; polyester resin; polyurethane resin; and the like. A foaming agent may also be added to the material. The cushioning portion33preferably has a thickness of 1 μm to 100 μm (the thickness of the cushioning portion33is exaggeratedly illustrated inFIG. 3).

The cushioning portion33is formed by extrusion-molding the aforementioned material, or applying the aforementioned material to the inner surface of the corrugated tube27(the manufacturing method is not limited to a specific method).

For a little more detailed description of the molding, a two-layer extrusion molding machine with a crosshead, and a die for forming waves, which is disposed in front of a nozzle of the two-layer extrusion molding machine, are prepared, and molding is performed. The die for forming waves is configured to be opened and closed in a direction perpendicular to a material extrusion direction. After a material is extruded from the nozzle of the two-layer extrusion molding machine to have a tubular shape in which an outer layer serving as the body of the corrugated tube27overlaps an inner layer serving as the cushioning portion33, a tubular extruded article is formed into a bellows-like tubular shape by the die for forming waves. That is, the tubular extruded article is finally formed into a bellows-like tubular shape by pressing the tubular extruded article against, or vacuum-suctioning the tubular extruded article to wave-shaped grooves of the die inside the die for forming waves.

According to the corrugated tube27of the second embodiment, since the soft cushioning portion33is formed along the inner surface of the corrugated tube27, and the contact surface34of the cushioning portion33is formed into a ridged and grooved shape, the extendable and contractible grooved portions35can be circumferentially formed in the cushioning portion33at the positions corresponding to the inner grooved portions32. That is, since the inner grooved portions32is not completely filled with the cushioning portion33, the corrugated tube27can be easily bent. Accordingly, the corrugated tube27is capable of maintaining its own flexibility.

According to the corrugated tube27of the second embodiments, since the contact surface34of the cushioning portion33is smoothly formed, the occurrence of degradation in the quality of the covering outer surface caused by friction or contact between the covering outer surface of the conductive path26and the contact surface34can be prevented, or degradation in the quality of the covering outer surface can be considerably reduced.

As a result, according to the second embodiment, it is possible to provide the corrugated tube27in which the covering outer surface is not damaged during vibration of the conductive path26, and the occurrence of degradation in the quality of the covering outer surface caused by friction or contact between the corrugated tube27and the covering outer surface is prevented, and to provide the wireharness25configured to include the corrugated tube27.

According to the embodiments, the corrugated tube27made of resin is formed into a shape in which, when the corrugated tube27is seen from the outside, the outer grooved portions29and the outer ridged portions30are formed in the circumferential direction, the outer grooved portions29and the outer ridged portions30continuously alternate in the tube-axial direction, and the inner ridged portions31and the inner grooved portions32are formed on the inner surface of the corrugated tube27so as to respectively conform to the shapes of the outer grooved portions29and the outer ridged portions30.

The corrugated tube27may include the cushioning portion33that has hardness softer than that of the covering outer surface of the one or the multiple conductive paths26accommodated and protected by the corrugated tube27, and is integrally formed only in the apex portion of the inner ridged portion31.

According to this structure, it is possible to provide a corrugated tube in which the covering outer surface of the conductive path is not damaged during vibration of the conductive path.

The contact surface34of the cushioning portion33may be smoothly rounded.

According to this structure, it is possible to provide a corrugated tube in which the occurrence of degradation in the quality of the covering outer surface of the conductive path caused by friction or contact between the corrugated tube and the covering outer surface is prevented.

The wireharness25may include the corrugated tube27with the aforementioned structure, and the one or the multiple conductive paths26accommodated and protected by the corrugated tube27.

According to this structure, it is possible to provide a wireharness configured to include a corrugated tube in which the covering outer surface is not damaged during vibration of the conductive path, and the occurrence of degradation in the quality of the covering outer surface caused by friction or contact between the corrugated tube and the covering outer surface is prevented.

According to this structure, since the soft cushioning portions are formed only in the apex portions of the inner ridged portions, the original shapes of the inner grooved portions are maintained. That is, since the inner grooved portions are not coated with the cushioning portion, the corrugated tube can be easily bent, and, as a result, flexibility of the corrugated tube is not reduced. Since the contact surfaces of the cushioning portions are smoothly rounded, the occurrence of degradation in the quality of the covering outer surface caused by friction or contact between the covering outer surface of the conductive path and the contact surface is prevented, or degradation in the quality of the covering outer surface is considerably reduced.

According to embodiments, the corrugated tube27may include the cushioning portion33that has hardness softer than that of the covering outer surface of the one or the multiple conductive paths26accommodated and protected by the corrugated tube27, and is integrally formed along the inner surface of the corrugated tube27. The cushioning portion33may include the contact surface34conforming to the ridged shapes of the inner ridged portions31and the grooved shapes of the inner grooved portions32.

According to this structure, it is possible to provide a corrugated tube in which the covering outer surface of one or multiple conductive path is not damaged during vibration of the conductive path.

The contact surface34may be smoothly formed at least at the positions of the inner ridged portions31.

According to this structure, it is possible to provide a corrugated tube in which the occurrence of degradation in the quality of the covering outer surface of one or multiple conductive path caused by friction or contact between the corrugated tube and the covering outer surface is prevented.

The wireharness25may include the corrugated tube27with the aforementioned structure, and the one or the multiple conductive paths26accommodated and protected by the corrugated tube27.

According to this structure, it is possible to provide a wireharness configured to include a corrugated tube in which the covering outer surface of one or multiple conductive path is not damaged during vibration of the conductive path, and the occurrence of degradation in the quality of the covering outer surface caused by friction or contact between the corrugated tube and the covering outer surface is prevented.

According to this structure, since the soft cushioning portion is formed along the inner surface of the corrugated tube, and the contact surface of the cushioning portion is formed into a ridged and grooved shape, the grooved portions (extendable and contractible grooved portions) are circumferentially formed at the positions corresponding to the inner grooved portions. That is, since the inner grooved portions are not filled with the cushioning portion, the corrugated tube can be easily bent, and, as a result, flexibility of the corrugated tube is not reduced. Since the contact surface of the cushioning portion is smoothly formed, the occurrence of degradation in the quality of the covering outer surface of one or multiple conductive paths caused by friction or contact between the covering outer surface and the contact surface is prevented, or degradation in the quality of the covering outer surface is considerably reduced.

The present invention is not limited to the above embodiments, and the present invention may be modified in various forms insofar as the modifications do not depart from the purport of the present invention.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS