Cable water stop structure and wire harness

A cable water stop structure for a cable that includes plural insulated wires and a sheath covering the plural insulated wires includes a heat shrinkable tube that is shrunk to wrap around an end of the sheath and the plurality of insulated wires extending from the end, and a cover that is attached to sandwich the end of the sheath, the plurality of insulated wires extending from the end and the heat shrinkable tube. The cover includes a gripping portion gripping the heat shrinkable tube to restrict the heat shrinkable tube from moving along a cable longitudinal direction.

The present application is based on Japanese patent application No. 2017-094248 filed on May 10, 2017, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a cable water stop structure and a wire harness using the cable water stop structure.

2. Description of the Related Art

In recent years, electrically operated brake systems are used in a vehicle such as an automobile. The known electrically operated brake systems include an electro-mechanical brake (EMB) system and an electric parking brake (EPB) system.

The electro-mechanical brake system, which is also simply called electric friction brake or electric brake, is configured such that a rotational drive force of a dedicated electric motor mounted on each wheel of a vehicle is controlled according to the operation amount (tread force or displacement amount) of a brake pedal by a driver, so that a piston driven by the electric motor presses brake pads against a disc rotor of the wheel to generate a braking force intended by the driver.

The electric parking brake system is configured such that a dedicated electric motor provided on each wheel of a vehicle is driven based on an operation performed on a parking brake activation switch by a driver after stopping a vehicle, so that a piston driven by the electric motor presses brake pads against a disc rotor of the wheel to generate a braking force.

Also, in recent years, sensors, e.g., wheel speed sensor (also called ABS (Anti-Lock Brake System) sensor) for detecting the speed of a wheel rotation during motion, air pressure sensor for detecting air pressure of a tire and temperature sensor, etc., are often mounted on wheels of vehicles.

Consequently, the wheel side and the vehicle body side are connected through composite cables in which a signal line for a sensor mounted on a wheel and/or a signal line for controlling an electro-mechanical brake system and a power line for supplying power to an electric motor of electro-mechanical brake system or electric parking brake system are housed in one sheath.

Where the wire harness is applied for a composite cable, the connection destinations of plural insulated wires (the above-mentioned signal and power lines) provided in the cable are different and the insulated wires thus need to be branched off for each connection destination. At the branching portion, the insulated wires are exposed from the sheath and there is thus a risk that water trickles down along the insulated wires and enters inside the sheath. Therefore, a water stop property (i.e., waterproofness) to stop water from entering inside the sheath needs to be ensured at the portion where the insulated wires are exposed from the sheath.

As a solution, a cable water stop structure may be devised which is configured to prevent water ingress into the inside of the sheath at the portion where the insulated wires are exposed from the sheath, for example, all of the sheath and the exposed insulated wires from the sheath being covered with a molded resin (see, e.g., JP 2016/91731 A). In this structure, however, if the molded resin is, e.g., urethan resin and the insulation of the insulated wire is formed of polyethylene, the molded resin does not adhere to the insulation and it is not possible to ensure the water stop property. To address this problem, a heat shrinkable tube may be further used for covering the molded resin and the cable or the insulated wires extending from the molded resin. In this case, however, the heat shrinkable tube needs to be used for each portion from which the insulated wire or the cable extends and, therefore, the manufacture is very complicated.

Thus, collectively covering a sheath and insulated wires extending from an end of the sheath with a single heat shrinkable tube is proposed so as to ensure the water stop property at the branching portion (see, e.g., JP 2015/73414 A).

JP 2011/253681 A also discloses another prior art that may be related to the present invention.

SUMMARY OF THE INVENTION

Even if the sheath and the insulated wires extending from the end of the sheath are collectively covered with a single heat shrinkable tube, the water stop property may not be ensured under a high-temperature environment of, e.g., 120° C. or more, since the resin tube may be shrunk again and detached from the sheath at the high temperature.

It is an object of the invention to provide a cable water stop structure that prevents water ingress into the inside of the sheath more securely at a portion where insulated wires are exposed from a sheath, as well as a wire harness using the cable water stop structure.

According to an embodiment of the invention, a cable water stop structure for a cable that comprises a plurality of insulated wires and a sheath covering the plurality of insulated wires comprises:

a heat shrinkable tube that is shrunk to wrap around an end of the sheath and the plurality of insulated wires extending from the end; and

a cover that is attached to sandwich the end of the sheath, the plurality of insulated wires extending from the end and the heat shrinkable tube,

wherein the cover comprises a gripping portion gripping the heat shrinkable tube to restrict the heat shrinkable tube from moving along a cable longitudinal direction.

According to another embodiment of the invention, a wire harness comprises:

a cable comprising a plurality of insulated wires and a sheath covering the plurality of insulated wires;

a heat shrinkable tube that is shrunk to wrap around an end of the sheath and the plurality of insulated wires extending from the end; and

a cover that is attached to sandwich the end of the sheath, the plurality of insulated wires extending from the end and the heat shrinkable tube,

wherein the cover comprises a gripping portion gripping the heat shrinkable tube to restrict the heat shrinkable tube from moving along a cable longitudinal direction.

Effects of the Invention

According to an embodiment of the invention, a cable water stop structure can be provided that prevents water ingress into the inside of the sheath more securely at a portion where insulated wires are exposed from a sheath, as well as a wire harness using the cable water stop structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment

An embodiment of the invention will be described below in conjunction with the appended drawings.

Description of a Vehicle in which a Wire Harness is Used

FIG. 1is a schematic diagram illustrating a configuration of a vehicle in which a wire harness in the present embodiment is used.

A vehicle1has four wheel-wells100on a vehicle body10, and two front wheels11and two rear wheels12are respectively arranged in the wheel-wells100. In the present embodiment, the vehicle1is a front-wheel-drive vehicle and the front wheels11are driven by a drive force from a drive source (not shown) such as an engine or electric motor. In other words, in the present embodiment, the front wheels11are drive wheels and the rear wheels12are non-driven wheels.

The vehicle1also has two electric parking brake units130and a control unit14. The electric parking brake units130are provided so as to respectively correspond to the two rear wheels12, are activated by a current supplied from the control unit14and generate a braking force applied to the rear wheels12. The control unit14can detect an operating state of a parking brake activation switch140provided inside a passenger compartment of a vehicle and a driver can activate or deactivate the electric parking brake units130by an on/off operation of the parking brake activation switch140.

When a driver turns the parking brake activation switch140from, e.g., an off state to an on state during when the vehicle is not in motion, an operating current for operating the electric parking brake units130is output from the control unit14for a predetermined period of time (e.g., for 1 second). The electric parking brake units130are thereby activated and generate a braking force applied to the rear wheels12. The activated state of the electric parking brake units130is maintained until a current to deactivate the electric parking brake units130is output from the control unit14. In this manner, the electric parking brake units130generate a braking force mainly after the vehicle1stops.

The control unit14outputs a current to deactivate the electric parking brake units130when the parking brake activation switch140is switched from the on state to the off state by an operation of the driver. The control unit14also outputs a current to deactivate the electric parking brake units130when, e.g., an accelerator pedal is depressed, in addition to when the parking brake activation switch140is turned off.

Meanwhile, each of the front wheels11and the rear wheels12is provided with a wheel speed sensor (ABS sensors)131for detecting a wheel speed. The wheel speed sensor131itself is a well-known wheel speed sensor which has a magnetic field sensing element for detecting a magnetic field of an annular magnetic encoder rotating together with the front wheel11or the rear wheel12and detects a wheel speed (a rotation speed of the front wheel11or the rear wheel12) based on the cycle of change in the direction of the magnetic field.

The control unit14is electrically connected to the wheel speed sensors131of the front wheels11through front wheel wire groups151each composed of plural electric wires and front wheel wire harnesses152. In each junction box153which is fixed to the vehicle body10, the front wheel wire group151is connected to the front wheel wire harness152. The junction boxes153are respectively arranged in the vicinities of the pair of right and left front wheels11.

The control unit14is also electrically connected to the electric parking brake units130and the wheel speed sensors131of the rear wheels12through rear wheel wire groups154each composed of plural electric wires and wire harnesses2in the present embodiment. In each junction box155which is fixed to the vehicle body10, the rear wheel wire group154is connected to the wire harness2. The junction boxes155are respectively arranged in the vicinities of the pair of right and left rear wheels12.

The front wheel wire groups151are arranged in a bundled state on a wiring path150provided on the vehicle body10. The rear wheel wire groups154are also arranged in a bundled state on the wiring path150provided on the vehicle body10, in the same manner as the front wheel wire groups151.

One end of the front wheel wire harness152is connected to the wheel speed sensor131of the front wheel11, and the other end is housed in the junction box153. One end of the rear wheel wire harness2is connected to the electric parking brake unit130and the wheel speed sensor131of the rear wheel12, and the other end is housed in the junction box155. The front wheel wire harnesses152and the rear wheel wire harnesses2are bent in accordance with vertical movement of the front wheels11and the rear wheels12relative to the vehicle body10during motion of the vehicle1, and are thus required to have a high flexibility.

Description of Cable Used for the Wire Harness2

FIG. 2is a cross sectional view showing a cable3constituting the wire harness2. The cable3has a pair of power lines31, a pair of signal lines32, and a sheath33by which the pair of power lines31and the pair of signal lines32are covered together. In the present embodiment, the pair of power lines31and the pair of signal lines32are held by the sheath33via a lubricant34. The power lines31and the signal lines32are one aspect of the insulated wire of the invention.

A first power connector (not shown) used for connection to the electric parking brake130is attached to one end of the pair of power lines31, and a second power connector (not shown) used for connection to the rear wheel wire group154in the junction box155is attached to the other end of the pair of power lines31.

The wheel speed sensor131is attached to one end of the pair of signal lines32, and a signal line connecting connector (not shown) used for connection to the rear wheel wire group154in the junction box155is attached to the other end.

The wire harness2in the present embodiment is provided with the cable3, the first power connector, the second power connector, the wheel speed sensor131and the signal line connecting connector. In the wire harness2, the pair of power lines31and the pair of signal lines32exposed from the sheath33are branched off, and a cable water stop structure4in the present embodiment is used at a branching portion3ato prevent ingress of water inside the sheath33. The details will be described later.

The pair of power lines31are used to supply a current to the electric parking brake unit130. The pair of signal lines32are used to transmit a detection signal from the wheel speed sensor131to the control unit14. That is, vehicle state quantity detection signals indicating the running state of the vehicle1are transmitted to the control unit14through the pair of signal lines32when the vehicle1is in motion.

Each of the pair of power lines31is an insulated wire formed by covering a central conductor310comprising a highly conductive wire of copper, etc., with an insulation311formed of an insulating resin. The central conductor310is a twisted wire formed of plural strands. The insulation311is formed of, e.g., a crosslinked PE (polyethylene) or a crosslinked flame-retardant PE (polyethylene).

The pair of signal line32is an insulated wire formed by covering a central conductor320comprising a highly conductive wire of copper, etc., with an insulation321formed of an insulating resin. The central conductor320is a twisted wire formed of plural strands. The insulation321is formed of, e.g., a crosslinked PE (polyethylene) or a crosslinked flame-retardant PE (polyethylene). The signal line32has a smaller outer diameter than the power line31.

The power lines31and the signal lines32are not covered with a shield conductor. In other words, any conductive members for shielding electromagnetic wave are not arranged between the power lines31and the signal lines32. This is because it is not necessary to provide a shield conductor between the signal lines32and the power lines31since current flows through the power lines31mainly during when the vehicle1is not in motion and electrical signals are transmitted through the signal lines32mainly during when the vehicle1is in motion. That is, when a current flows through the pair of power lines31, electromagnetic wave generated by the current can affect a potential difference between the pair of signal lines32. However, since the control unit14can be set to ignore the electrical signals transmitted through the signal lines32during when the vehicle1is not in motion, i.e., when a vehicle speed is zero, an adverse effect on travel of the vehicle1can be avoided. In addition, not covering the signal lines32with a shield conductor increases flexibility and resulting bendability of the cable3and also contributes to weight reduction and cost reduction of the cable3.

The power lines31and the signal lines32are alternately arranged in a circumferential direction of the cable3, and the pair of power lines31and the pair of signal lines32are twisted together.

The sheath33is formed of an insulating resin. In the present embodiment, the sheath33is formed of polyurethane which is excellent in flexibility and durability.

The lubricant34formed of talc (Mg3Si4O10(OH)2) or silica (SiO2), etc., and having a particle size of, e.g., 5 to 50 μm can be suitably used. The particle size here means a particle diameter obtained by a method defined by JIS 8801 such as sieve analysis, microscopy, a laser diffraction scattering method, an electrical sensing method or a chromatography method. Alternatively, a paper tape or lubricant oil may be used as the lubricant34. Use of lubricant34allows the pair of power lines31and the signal lines32to move smoothly inside the sheath33, and this increases bendability and also facilitates termination of the cable3.

Description of Cable Water Stop Structure

FIG. 3is a perspective view showing a cable water stop structure in the present embodiment, andFIG. 4is a cross sectional view thereof.

As shown inFIGS. 3 and 4, the cable water stop structure4in the present embodiment is a structure for stopping water from entering inside the sheath33at the portion where the power lines31and the signal lines32are exposed from the sheath33of the cable3. At the branching portion3aof the cable3, the sheath33is partially removed and the power lines31and the signal lines32are exposed. Although the pair of power lines31are branched off from the pair of the signal lines32at the branching portion3ain this example, the configuration at the branching portion3aonly needs to be such that at least some of plural insulated wires extending from the sheath33extend in a different direction. In the present embodiment, the pair of signal lines32extend in a direction parallel to the longitudinal direction of the cable3having the sheath33, and the pair of power lines31extend in a direction orthogonal to the extending direction of the pair of signal lines32. In other words, the pair of signal lines32and a portion of the cable3having the sheath33are arranged on a straight line, and the pair of power lines31are branched off and extend in a direction orthogonal to the straight line.

The cable water stop structure4is to prevent water from entering inside the sheath33of the cable3, and is provided on an end of the sheath33and spanning over the power lines31and the signal lines32extending from the sheath33.

Description of the Heat Shrinkable Tube5

The cable water stop structure4is provided with a heat shrinkable tube5which covers an end of the sheath33as well as the plural insulated wire (the pair of power lines31and the pair of signal lines32) extending out therefrom.

The heat shrinkable tube5has a heat-shrinkable resin tube51and an adhesive layer (not shown) formed of an adhesive provided on the inner surface of the resin tube51. The resin tube51formed of polyolefin is used in the present embodiment. The adhesive constituting the adhesive layer is a hot melt adhesive such as epoxy resin.

The adhesive constituting the adhesive layer of the heat shrinkable tube5is melted by heat applied to shrink the resin tube51, enters a gap between the resin tube51, the power lines31, the signal lines32and the sheath33, and cures and seals the gap between the resin tube51, the power lines31, the signal lines32and the sheath33after shrinking.

In the present embodiment in which the four-core cable3having the pair of power lines31and the pair of signal lines32is used, each gap between the insulated wires is larger than that in, e.g., a two-core cable. Therefore, in the present embodiment, another adhesive is separately provided in addition to the adhesive layer of the heat shrinkable tube5so that the gaps between insulated wires (the pair of power lines31and the pair of signal lines32) can be reliably sealed.

In detail, the heat shrinkable tube5is provided after annular (short cylindrical) adhesives52(seeFIGS. 7A and 7B) are pre-arranged around the both power lines31and the both signal lines32, and then, heat is applied to shrink the resin tube51and also to melt the annular adhesives52to fill the gaps between the insulated wires. The annular adhesive52preferably has the same components as the adhesive layer of the heat shrinkable tube5and can be a hot melt adhesive such as epoxy resin. A portion denoted by the reference numeral53inFIG. 4is an adhesive portion formed by melting and subsequent curing of the adhesive layer of the heat shrinkable tube5and the annular adhesives52.

A portion of the heat shrinkable tube5overlapping the sheath33has a length L2which is preferably not less than 5 mm, desirably not less than 10 mm. This is because when the length L2is as short as less than 5 mm, there is a higher risk that the heat shrinkable tube5comes off from the sheath33in a high-temperature environment. The length L2is 20 mm in this example. A portion of the heat shrinkable tube5not overlapping the sheath33(i.e., a portion of the heat shrinkable tube5covering the power lines31and the signal lines32extending from the sheath33) has a length L1allowing sufficient water stop property to be ensured by sealing with the adhesive (the adhesive layer of the heat shrinkable tube5and the adhesives52), and the length L1is preferably not less than 5 mm, desirably not less than 10 mm. The length L1is 10 mm in this example.

Description of the Protective Cover6

FIG. 5is a cross sectional view showing a protective cover6. As shown inFIGS. 3 to 5, the cable water stop structure4is further provided with the protective cover6which is a cover of the invention and is attached to sandwich an end of the sheath33, the plural insulated wires (the pair of power lines31and the pair of signal line32) extending out therefrom and the heat shrinkable tube5. The protective cover6in the present embodiment is a branching portion-protecting cover which is attached to the branching portion3aand protects the branching portion3a.

The protective cover6is composed of two split bodies61and62, and is configured such that engagement protrusions62aprovided on the split body62are engaged with engagement holes61aprovided on the split body61and the two split bodies61and62are thereby fixed to each other. The means for fixing the two split bodies61and62to each other is not limited to the configuration shown in the drawing. However, the means for fixing the two split bodies61and62to each other is desirably capable of easily fixing the two split bodies61and62to each other by one-touch operation and also capable of firmly fixing the two split bodies61and62with strength enough to grip the heat shrinkable tube5. In addition, although the two split bodies61and62are separate members in the present embodiment, the two split bodies61and62may be integrally coupled by hinges.

The protective cover6has a gripping portion6awhich grips the heat shrinkable tube5to restrict the heat shrinkable tube5from moving along a cable longitudinal direction. In the cable water stop structure4of the present embodiment, the heat shrinkable tube5is gripped by the gripping portion6aof the protective cover6and displacement of the heat shrinkable tube5in a high-temperature environment is thereby prevented.

Since the gripping portion6aneeds to firmly grip the heat shrinkable tube5in a high-temperature environment, the protective cover6is desirably formed of a resin having a softening temperature higher than a shrinkage temperature of the heat shrinkable tube5. More preferably, the softening temperature of the protective cover6is not less than 150° C. In detail, the protective cover6formed of PBT (polybutylene terephthalate) or nylon can be suitably used. The shrinkage temperature of the heat shrinkable tube5here is a temperature at which the resin tube51starts to shrink and the inner diameter thereof is reduced by not less than 1% of the inner diameter before shrinking. Meanwhile, the softening temperature is Vicat softening temperature specified in JIS K 7206 and is a temperature at which the resin starts to deform.

The gripping portion6agrips a portion of the heat shrinkable tube5covering the sheath33. The reason is as follows: if the gripping portion6agrips a portion of the heat shrinkable tube5covering the insulated wires (the pair of power lines31and the pair of signal lines32), the resin tube51, which cannot expand radially outward in a high-temperature environment due to contact with the gripping portion6aand thus expands radially inward, may squeeze the adhesive (the adhesive layer of the heat shrinkable tube5and the adhesives52) out of the resin tube51, resulting in that water stop property cannot be ensured.

The gripping portion6ahas plural grooves6bformed on the inner surface thereof along a direction perpendicular to the cable longitudinal direction. When the heat shrinkable tube5is gripped by the gripping portion6a, the grooves6breceives a portion of the wall of the resin tube51dodging the pressure of protrusions between the grooves6b, and thereby strongly restricts axial movement of the resin tube51. Although four grooves6bare spaced apart in the longitudinal direction in this example, the number of the grooves6bis not limited thereto. In addition, the grooves6bdo not needs to be exactly perpendicular to the cable longitudinal direction, and may be slightly off (specifically, within 10° with respect to the cable longitudinal direction).

Grip strength of the gripping portion6ais not specifically limited, but is preferably adjusted so that movement of the heat shrinkable tube5in a high-temperature environment of, e.g., not less than 120° C. can be restricted. In more detail, the inner diameter of the gripping portion6a(the inner diameter of the protrusions between the grooves6b) is desirably not less than 1 mm smaller than the outer diameter of the non-gripped sheath33, so that the outer diameter of the sheath33is reduced by not less than 1 mm by pressure of the protrusions between the grooves6bwhen gripped by the gripping portion6a.

A length L3of the gripping portion6aalong the cable longitudinal direction is preferably not less than 5 mm and not more than 15 mm. This is because when the length L3is less than 5 mm, a sufficient gripping force may not be obtained and it may not be possible to prevent displacement of the heat shrinkable tube5in a high-temperature environment. Meanwhile, when the length L3is more than 15 mm, the size of the protective cover6is increased and this may cause a problem such as a decrease in the degrees of freedom of routing layout of the wire harness2. In the present embodiment, the length L3is about 10 mm. In addition, in the present embodiment, the heat shrinkable tube5extends toward the extension side of the cable3beyond the gripping portion6a.

The protective cover6also has a wall portion6cwhich is in contact with an end of the heat shrinkable tube5on the extension side of the plural insulated wires (the pair of power lines31and the pair of signal lines32) and thereby restricts the heat shrinkable tube5from moving toward the extension side of the plural insulated wires. A through-hole6dallowing passage for the pair of power lines31and the pair of signal lines32is formed on the wall portion6c. In addition, a hollow-cylindrical tube housing6efor housing a portion of the heat shrinkable tube5covering the insulated wires is provided between the wall portion6cand the gripping portion6a. The wall portion6cis arranged to close an opening of the tube housing6eon the opposite side to the gripping portion6a.

In the present embodiment, the wall portion6cserves to restrict movement of the heat shrinkable tube5and also serves to prevent the adhesive (the adhesive layer of the heat shrinkable tube5and the adhesives52) inside the resin tube51from flowing away in a high-temperature environment. The through-hole6dis desirably as small as possible so that the adhesive does not flow away through the through-hole6d. In addition, the wall portion6cis desirably in abutting contact with an end face of the resin tube51so that the adhesive does not flow away through a gap between the wall portion6cand the resin tube51. However, it is not limited thereto and a slight gap may be present between the wall portion6cand the end face of the resin tube51.

In the configuration in which the pair of power lines31and the pair of signal lines32are gripped by the through-hole6dwith a reduced size, vibration caused by swinging of the power lines31and the signal lines32is prevented from being transferred to the heat shrinkable tube5.

A branching-portion housing6ffor housing the branching portion3aof the power lines31and the signal lines32is provided on a side of the wall portion6copposite to the tube housing6e. The branching-portion housing6fhas a first opening6gallowing the pair of power lines31to extend out and a second opening6hallowing the pair of signal lines32to extend out. Although the extending direction of the pair of power lines31extending from the first opening6gis orthogonal to the extending direction of the pair of signal lines32extending from the second opening6hin this example, the extending directions of the insulated wires are not limited thereto.

A first corrugated-tube holding portion6ifor holding a first corrugated tube21covering the pair of power lines31extending from the protective cover6is circumferentially formed at an edge of the first opening6g. Likewise, a second corrugated-tube holding portion6jfor holding a second corrugated tube22covering the pair of signal lines32extending from the protective cover6is circumferentially formed at an edge of the second opening6h.

The corrugated tubes21and22are bellows-shaped resin tubes and are provided to prevent the power lines31and the signal lines32from being damaged by chipping. The corrugated tubes21and22are provided to respectively entirely cover the pair of power lines31from the protective cover6to the first power connector and the pair of signal lines32from the protective cover6to the wheel speed sensor131. The corrugated-tube holding portions6iand6jrespectively have grooves6mand6non the inner surfaces thereof. The split bodies61and62are integrated in a state that raised portions (large-diameter portions) of the corrugated tubes21and22are fitted to the grooves6mand6nso that the protective cover6sandwiches end portions of the corrugated tubes21and22, and the corrugated tubes21and22are thereby held. In the present embodiment, an axial direction of the first corrugated-tube holding portion6iis orthogonal to an axial direction of the gripping portion6a, and an axial direction of the second corrugated-tube holding portion6jcoincides with the axial direction of the gripping portion6a.

Although the protective cover6described in the present embodiment is a branching portion-protecting cover which covers the branching portion3a, it is not limited thereto. The protective cover6may be a connector cover (connector housing) which holds connection terminals provided at ends of the plural insulated wires. In this case, a connection terminal holding portion for holding the connections terminals is provided in place of the branching-portion housing6fshown in the drawing.

Procedure to Assemble the Wire Harness2

When assembling the wire harness2, firstly, the pair of power lines31and the pair of signal lines32are exposed at an end of the cable3by cutting off a predetermined length of the sheath33, as shown inFIG. 6. AlthoughFIG. 6shows the pair of power lines31and the branched pair of signal lines32so as to correspond toFIG. 3 or 4, it is not necessary to branch off at this stage.

After that, the annular adhesives52are separately arranged around the power lines31and the signal lines32, as shown inFIGS. 7A and 7B. The adhesives52are melted when shrinking the heat shrinkable tube5, enter the gap between the power lines31, the signal lines32and the resin tube51, and fill and seal the gap. When the number of the cores of the cable3is three or more as is in the present embodiment in which the four-core cable3is used, it is desirable to separately provide the adhesives52since the gaps between the cores are larger and it may not be possible to fill the gaps only with the adhesive layer of the heat shrinkable tube5. That is, use of the adhesives52allows the thickness of the adhesive layer of the heat shrinkable tube5to be reduced even when the gaps between the cores of the cable3are large, and such thin adhesive layer allows the heat shrinkable tube5to be thinner and prevents misalignment of the heat shrinkable tube5due to melting of the adhesive layer in a high-temperature environment.

The annular adhesives52are inserted from the ends of the power lines31and the signal lines32and are arranged in contact with the sheath33. Although the adhesive52is individually arranged around each insulated wire (each power line31and each signal line32) in then present embodiment, it may be configured such that plural (e.g., two) insulated wires are covered with one adhesive52. In addition, the shape of the adhesive52is not limited to the annular shape. For example, columnar adhesives52may be arranged between the insulated wires.

After that, the heat shrinkable tube5is provided so that an end of the sheath33and the pair of power lines31and the pair of signal lines32extending out therefrom are covered as shown inFIG. 8A, and the heat shrinkable tube5is then shrunk by heating. In the present embodiment, the adhesives52separately provided are arranged inside the heat shrinkable tube5. Therefore, if heat is applied for a long time so that the adhesives52are sufficiently melted, the resin tube51of the heat shrinkable tube5may be excessively shrunk, which reduces the length L2of the heat shrinkable tube5overlapping the sheath33.

To address this problem, heat is applied by irradiating near-infrared light in a state that the cable3and a portion of the heat shrinkable tube5overlapping the sheath33are gripped by a jig7, as shown inFIG. 8B. In this case, even when heat is applied long enough to sufficiently melt the adhesives52, misalignment of the heat shrinkable tube5(movement of the heat shrinkable tube5toward the extension side of the power lines31and the signal lines32) can be prevented, resulting in that the length L2described above can be sufficient and water stop property can be ensured.

Once irradiation of near-infrared light is stopped to terminate heating, the adhesive portion53is formed due to curing of the adhesives52and the adhesive layer of the heat shrinkable tube5, and the gap between the resin tube51, the power lines31, the signal lines32and the sheath33is sealed.

The portion of the heat shrinkable tube5(the resin tube51) gripped by the jig7(an end portion of the heat shrinkable tube5on a side overlapping the sheath33) is not directly exposed to near-infrared light and is hardly shrunk since the near-infrared light is blocked by the jig7. Therefore, after the adhesives52and the adhesive layer of the heat shrinkable tube5are cured and the resin tube51is positioned, near-infrared light is irradiated again onto the unshrunk portion of the resin tube51so that the entire resin tube51is shrunk.

After that, an end of the sheath33, the plural insulated wires extending out therefrom and the heat shrinkable tube5are sandwiched by the two split bodies61and62, and then, the two split bodies61and62are fixed to each other. At this time, the pair of power lines31are inserted into the first corrugated tube21, and the first corrugated tube21is arranged so that an end thereof is held by the first corrugated-tube holding portion6i. Meanwhile, the pair of signal lines32are inserted into the second corrugated tube22, and the second corrugated tube22is arranged so that an end thereof is held by the second corrugated-tube holding portion6j.

Once the two split bodies61and62are fixed to each other, the protective cover6is formed and the heat shrinkable tube5is gripped by the gripping portion6aof the protective cover6and is restricted from moving in the cable longitudinal direction. The wire harness2is thereby obtained.

Functions and Effects of the Embodiment

As described above, the cable water stop structure4in the present embodiment is provided with the heat shrinkable tube5shrunk to wrap around an end of the sheath33and the plural insulated wires (the power lines31and the signal lines32) extending out therefrom, and the protective cover6which is attached to sandwich the end of the sheath33, the plural insulated wires (the power lines31and the signal lines32) extending out therefrom and the heat shrinkable tube5and has the gripping portion6agripping the heat shrinkable tube5to restrict the heat shrinkable tube5from moving along the cable longitudinal direction.

In a high-temperature environment, the heat shrinkable tube5generally starts to shrink and is likely to be misaligned. When the heat shrinkable tube5has an adhesive layer as is in the present embodiment, the adhesive layer is melted in a high-temperature environment and the heat shrinkable tube5is more likely to be misaligned. However, since the heat shrinkable tube5is gripped by the gripping portion6aof the protective cover6in the present embodiment, it is possible to prevent misalignment of the heat shrinkable tube5in a high-temperature environment and water ingress into the inside of the sheath33thus can be prevented more reliably. In addition, in the present embodiment, it is not necessary to provide the heat shrinkable tube on every portion from which the cable3or the insulated wire extends out, and water ingress into the inside of the sheath33can be prevented by using only one heat shrinkable tube5(and the protective cover6). Thus, the structure is simple and the number of components is reduced, thereby contributing to reduce the cost of the wire harness2.

The branching portion3acould be covered with, e.g., a molded resin. In this case, however, it takes time to cool down after forming the molded resin and the manufacturing cost thus increases. By using the separately molded protective cover6as is in the present embodiment, it is possible to eliminate such cooling time and thus to reduce the manufacturing cost.

Water stop property could be ensured by using a rubber packing such as O-ring. In this case, however, it is necessary to provide rubber packings around the sheath33as well as around each of the insulated wires (power lines31and the signal lines32) extending from the sheath33, and this increases the numbers of components and manufacturing processes. In addition to this, since these rubber packings need to have a small inner diameter to tightly squeeze the sheath33and the insulated wires, it takes much time and effort to attach the rubber packings. In contrast, in the present embodiment, the increase in the numbers of components and manufacturing processes can be suppressed since only one heat shrinkable tube5is used, and it is easy to attach the heat shrinkable tube5since it is only necessary to insert the heat shrinkable tube5having a relatively large inner diameter and then shrink the heat shrinkable tube5by heating.

Summary of the Embodiment

Technical ideas understood from the embodiment will be described below citing the reference numerals, etc., used for the embodiment. However, each reference numeral, etc., described below is not intended to limit the constituent elements in the claims to the members, etc., specifically described in the embodiment.

[1] A cable water stop structure (4) for a cable that comprises a plurality of insulated wires (31,32) and a sheath (33) covering the plurality of insulated wires (31,32), the cable water stop structure (4) comprising: a heat shrinkable tube (5) that is shrunk to wrap around an end of the sheath (33) and the plurality of insulated wires (31,32) extending from the end; and a cover (6) that is attached to sandwich the end of the sheath (33), the plurality of insulated wires (31,32) extending from the end and the heat shrinkable tube (5), wherein the cover comprises a gripping portion (6a) gripping the heat shrinkable tube (5) to restrict the heat shrinkable tube (5) from moving along a cable longitudinal direction.

[2] The cable water stop structure (4) defined by HU, wherein the cover (6) further comprises a wall portion (6c) that is in contact with an end of the heat shrinkable tube (5) on the extension side of the plurality of insulated wires (31,32) and thereby restricts the heat shrinkable tube (5) from moving toward the extension side of the plurality of insulated wires (31,32).

[3] The cable water stop structure (4) defined by HU or [2], wherein the gripping portion (6a) grips a portion of the heat shrinkable tube (5) covering the sheath (33).

[4] The cable water stop structure (4) defined by any of [1] to [3], wherein the gripping portion (6a) comprises a plurality of grooves (6b) formed on the inner surface thereof along a direction perpendicular to the cable longitudinal direction.

[5] The cable water stop structure (4) defined by any of [1] to [4], wherein the cover (6) further comprises a resin having a softening temperature that is higher than a shrinkage temperature of the heat shrinkable tube (5).

[6] The cable water stop structure (4) defined by any of [1] to [5], wherein the cover (6) further comprises a branching portion-protecting cover attached to a branching portion (3a) from which at least a part of the plurality of insulated wires (31,32) extends in a different direction.

[7] The cable water stop structure (4) defined by any of [1] to [5], wherein the cover (6) further comprises a connector cover that holds connection terminals provided at ends of the plurality of insulated wires (31,32).

[8] A wire harness (2), comprising: a cable (3) comprising a plurality of insulated wires (31,32) and a sheath (33) covering the plurality of insulated wires (31,32); a heat shrinkable tube (5) that is shrunk to wrap around an end of the sheath (33) and the plurality of insulated wires (31,32) extending from the end; and a cover (6) that is attached to sandwich the end of the sheath (33), the plurality of insulated wires (31,32) extending from the end and the heat shrinkable tube (5), wherein the cover comprises a gripping portion (6a) gripping the heat shrinkable tube (5) to restrict the heat shrinkable tube (5) from moving along a cable longitudinal direction.

Although the embodiment of the invention has been described, the invention according to claims is not to be limited to the embodiment described above. Further, please note that all combinations of the features described in the embodiment are not necessary to solve the problem of the invention.

The invention can be appropriately modified and implemented without departing from the gist thereof. For example, although the four-core cable3having the pair of power lines31and the pair of signal lines32is used in the embodiment, the number of insulated wires is not limited thereto and may be two, three or five or more. In addition, all insulated wires of the cable3may be only the power lines31or only the signal lines32.

Furthermore, the intended use of the signal line32is not limited to signal transmission from the wheel speed sensor131. For example, the signal line32may be used for, e.g., an air pressure sensor for detecting air pressure of the wheel11or12, or the cable3may be provided with plural signal lines32used for different purposes. In addition, the intended use of the power line31is not limited to power supply to the electric parking brake unit130, and the power line31may be used to supply power to, e.g., an electro-mechanical brake system.