Water stop structure for electric wire bundle

The purpose of the present invention is to allow a water stop performance between electric wires to be maintained as much as possible even when the electric wires are bent. A water stop structure for an electric wire bundle includes an electric wire bundle in which a plurality of electric wires are bundled together, a filler with which gaps between the plurality of electric wires are filled while maintaining fluidity and viscosity in at least a portion of an extension direction of the electric wire bundle, and a covering body covering a circumference of the portion of the electric wire bundle filled with the filler.

FIELD OF THE INVENTION

The present invention relates to a technology for stopping water between electric wires.

BACKGROUND OF THE INVENTION

In Patent Literature 1, a configuration is disclosed in which, at a portion of a wire harness that is inserted through a small-diameter tubular portion of a grommet, a sealing agent is applied to an electric wire group configuring the wire harness, an outer periphery of the sealing agent application portion is covered with a sheet, only both ends on opening sides of the sheet in a length direction are fastened with a tape, and the sealing agent is unlikely to penetrate to an exterior from the tape-fastened portion and is forced to penetrate toward a cross sectional center of the wire harness between the tapes. As the sealing agent, applying a high viscosity or a non-liquid sealing agent such as silicone is disclosed.

RELATED ART

Patent Literature

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

However, the sealing agent disclosed in Patent Literature 1 hardens in gaps between the electric wires after application. Therefore, when assembling the grommet to a vehicle or after doing so, the sealing agent may break when the electric wire bundle extending from the grommet is bent. Accordingly, there is a possibility that water stop performance cannot be maintained.

In order to avoid the above, a no bending zone of the electric wire bundle may be provided with some length at the front and back of the grommet.

However, due to a layout and the like for a space to arrange the grommet in the vehicle, it may be difficult to secure enough no bending zone of the electric wire bundle.

In view of this, a purpose of the present invention is to allow water stopping performance between electric wires to be maintained as much as possible even when an electric wire bundle is bent.

Means for Solving the Problems

In order to resolve the above-noted issues, a water stop structure for an electric wire bundle according to a first aspect includes an electric wire bundle in which a plurality of electric wires are bundled together, a filler with which gaps between the plurality of electric wires are filled while maintaining fluidity and viscosity in at least a portion of an extension direction of the electric wire bundle, and a covering body covering a circumference of the portion of the electric wire bundle filled with the filler. The filler has fluidity which enables flow so as to fill the gaps between the electric wires even when gaps are created while the covering body covers the circumference of the portion of the electric wire bundle filled with the filler.

A second aspect is the water stop structure for an electric wire bundle according to the first aspect, in which the filler is grease with water repellency.

A third aspect is the water stop structure for an electric wire bundle according to one of the first and second aspects, in which a fastening member is provided respectively to both end side portions of the portion of the electric wire bundle filled with the filler, in the extension direction of the electric wire bundle.

A fourth aspect is the water stop structure for an electric wire bundle according to any one of the first to the third aspects, further including a grommet having a tube into which the portion of the electric wire bundle filled with the filler is inserted, and a mounting portion that is formed so as to spread outward from the tube and that can be mounted to an attachment hole formed in an attachment panel.

A fifth aspect is the water stop structure for an electric wire bundle according to any one of the first to fourth aspects, in which penetration of the filler is between 200 to 400.

A sixth aspect is the water stop structure for an electric wire bundle according to any one of the first to fifth aspects, in which an oil separation degree of the filler after passing 24 hours at 100° C. is 0%.

A seventh aspect is the water stop structure for an electric wire bundle according to any one of the first to sixth aspects, in which an amount of evaporation of the filler after passing 22 hours at 100° C. is equal to or below 0.1%.

An eighth aspect is the water stop structure for an electric wire bundle according to the third aspect, in which the fastening member fastens the electric wire bundle such that the gaps between the plurality of electric wires are smaller than the other portions.

Effect of the Invention

According to the first aspect, the filler is filled in the gaps between the plurality of electric wires while maintaining fluidity and viscosity in at least a portion of the extension direction of the electric wire bundle, and the covering body covers the circumference of the portion of the electric wire bundle filled with the filler. Therefore, even when the electric wire bundle is bent, it is easy to maintain the state where the filler is filled in the gaps between the plurality of electric wires on an inner side of the covering body. In view of this, the water stop performance between the electric wires can be maintained as much as possible even when the electric wire bundle is bent.

According to the second aspect, the filler has water repellency and therefore, water infiltration due to a capillary state can be prevented.

According to the third aspect, the filler is prevented from escaping to an exterior through gaps between the electric wires. Accordingly, water stopping between the electric wires can be maintained as much as possible.

According to the fourth aspect, the grommet is mounted to the attachment hole formed in the attachment panel and the portion of the electric wire bundle filled with the filler is inserted through the tube of the grommet. Accordingly, water can be stopped by the grommet on two sides of the attachment panel.

According to the fifth aspect, it is easy to perform an operation for filing the filler in the gaps between the plurality of electric wires and also to maintain the state where the filler is filled in the gaps between the plurality of electric wires.

According to the sixth aspect, the oil separation degree of the filler is 0%, and therefore the water stop performance between the electric wires can be maintained as much as possible.

According to the seventh aspect, the amount of evaporation of the filler after passing 22 hours at 100° C. is equal to or below 0.1%, and therefore the water stop performance between the electric wires can be maintained as much as possible.

MODE FOR CARRYING OUT THE INVENTION

Hereafter, a water stop structure for an electric wire bundle according to an embodiment is described. Here, an example is described where a water stop structure for an electric wire bundle18is applied to an electric wire with grommet10.FIG. 1is a partial cross-sectional view of the electric wire with grommet10;FIG. 2is a partial cross-sectional view along a filler; andFIG. 3is a partial cross-sectional view along a fastening member.

The electric wire with grommet10includes an electric wire bundle12, a filler20, a covering body30, and a grommet40.

The electric wire bundle12has a configuration in which a plurality of electric wires13are bundled. The electric wire13includes a core wire and an insulation coating, for example. The electric wire13is an electric wire for a signal or an electric wire. A plurality of electric wire bundles12are assumed, for example, to be bundled together while branching in response to a wiring pathway in a vehicle; that is, a wire harness. In a state where the wire harness is assembled to the vehicle, the wire harness is used as a wiring member electrically connecting various electric components mounted in the vehicle. The portion of the wire harness which is inserted through the grommet40is configured by bundling together a plurality of electric wire bundles12into one. The electric wire bundle12may include an optical fiber cable and the like.

The filler20is filled in the gaps between the plurality of electric wires13while maintaining fluidity and viscosity in at least a portion of the electric wire bundle12in an extension direction. In this example, the filler20fills a portion of the electric wire bundle12which is inserted through a tube42of the grommet40, at a portion arranged in the extension-direction middle portion of the tube42.

The reason for the filler20to have fluidity is that, when the electric wire bundle12is bent and an external force acts on the filler20between the plurality of electric wire bundles12, water stop performance is maintained without fracturing the filler20. Therefore, the fluidity of the filler20refers to a property that can maintain the state where the gaps between the plurality of electric wires13are filled even when a portion or the entire electric wire13is moved, or that enables flow so as to fill gaps even when gaps are created.

The reason for the filler20to have viscosity is to maintain the state in which the filler20is present between the plurality of electric wires13without escaping outside from the gaps between the plurality of electric wires13. Therefore, the viscosity of the filler20refers to a property where the filler20does not escape outside of the covering body30through the gaps between the plurality of electric wires13in a state where the water stop structure for an electric wire bundle18is assembled to an application location of the electric wire bundle12.

As the filler20noted above, it is preferable to use grease, particularly grease having water repellency. For example, the filler20may be configured by only one type of grease. The grease is created by dispersing a thickening agent in raw material base oil. The grease having water repellency is grease that repels water on a surface without containing a surfactant, water-absorbing polymer, and the like.

The filler20noted above preferably maintains the fluidity and viscosity of the filler20during a period from manufacturing to assembling the water stop structure for an electric wire bundle18to the vehicle and the like, and furthermore, in a use environment of the water stop structure for an electric wire bundle18during a period of normal use of the vehicle after assembling the water stop structure for an electric wire bundle18to the vehicle and the like (such as in the environment of a vehicle engine compartment).

Preferable examples of the filler20are described later.

The covering body30covers a circumference of the portion of the electric wire bundle12filled with the filler20. Accordingly, the covering body30is configured such that the filler20does not escape outside from the gaps between the plurality of electric wires13. In this example, the covering body30covers, in the extension direction of the electric wire bundle12, the circumference of the portion of the electric wire bundle12filled with the filler20and the outer sides on both ends thereof.

As the covering body30, a configuration can be used where a sheet-shaped member in which the filler20does not pass through an inside or outside of the member is wrapped around an outer circumference of the electric wire bundle12. As the covering body30, for example, a foamed sheet such as urethane, and more preferably an independent foamed sheet can be used. The covering body may also have a configuration instead in which a thermal contraction tube and an adhesive tape are spirally wrapped.

In this example, the length dimension of the covering body30in the extension direction of the electric wire bundle12is greater than the length dimension of the tube42of the grommet40. Both end portions of the covering body30extend outward from both end portions of the tube42.

Also, in this example, a fastening member34is provided respectively to both end side portions of the portion of the electric wire bundle12filled with the filler20, in the extension direction of the electric wire bundle12. The fastening member34is wrapped around the outer circumference of the electric wire bundle12and fastens the electric wire bundle12such that the gaps between the plurality of electric wires13are smaller than the other portions. In this example, the fastening member34is configured by an adhesive tape that has an adhesive layer formed on one principal surface of a band-shaped substrate material wrapping around the electric wire bundle12. In addition, the fastening member34is wrapped around the outer circumference of the covering body30, which maintains the state where the covering body30is wrapped around the electric wire bundle12as well as keeping the covering body30adhered as tightly as possible to the outer circumference of the electric wire bundle12. Also, the fastening member34is preferably not provided, with respect to the covering body30, to a location where the filler20is filled. Accordingly, it is easy to keep the filler20between the two fastening members34. The fastening member may be directly wrapped around the outer circumference of the electric wire bundle on the inner circumferential side of the covering body. The fastening member may instead be configured by a bundling band, for example.

FIG. 3illustrates a state where the filler20is not present between the plurality of electric wires13on the inner circumferential side of the fastening member34; however, in this portion also, the filler20may be partially escaped and filled in the gaps between the plurality of electric wires13.

In this example, the fastening member34is provided at a portion located further inward than both end portions of the tube42of the grommet40relative to the outer circumference of the covering body30.

The grommet40includes the tube42and a mounting portion50. Here, the entire grommet40is a member integrally die-molded with an elastic member such as rubber.

The tube42is a tubular portion into which the portion of the electric wire bundle12filled with the filler20is inserted. The tube42is preferably set to an inner diameter dimension that is smaller than an outer diameter dimension of the electric wire bundle12, and the electric wire bundle12is inserted inside the tube42in a state where the tube42is expanded. In this state, the tube42fastens the electric wire bundle12. Depending also on a force by which the tube42fastens the electric wire bundle12, the filler20is pressed so as to be oriented toward a center of the electric wire bundle12, enabling the filler20to fill the gaps between the plurality of electric wires13more reliably.

The mounting portion50is formed so as to spread outward from the tube42and is configured to be mountable to an attachment hole8hformed on an attachment panel8.

In this example, the attachment panel8is a panel-like portion arranged in a state in which the electric wire bundle12is inserted therethrough. The attachment panel8is assumed to be a metal attachment panel that separates an engine compartment and a vehicle cabin of the vehicle. A circular attachment hole8his formed in the attachment panel8. By mounting the grommet40that is mounted on the electric wire bundle12to the attachment hole8h, the electric wire bundle12passes through the attachment hole8h. In this state, the grommet40seals the attachment hole8haround the electric wire bundle12to divide the two sides of the attachment panel such that water does not pass through as well as to protect the electric wire bundle12from a circumferential edge portion of the attachment hole8h.

More specifically, the mounting portion50includes a mounting main body52that is mounted to the attachment hole8hand a coupling portion54that couples the mounting main body52and the tube42.

The mounting main body52is formed annularly, more specifically in an annular shape that gradually contracts in diameter from one side of an axis direction to the other side. On the outer circumference of the mounting main body52, an annular groove53is formed in which the circumferential edge portion of the attachment hole8hcan be installed. Then, when the mounting main body52is pressed into the attachment hole8hwith the end portion of the mounting main body52having the smaller outer diameter in front, the portion of the mounting main body52contacting the circumferential edge portion of the attachment hole8his reduced in diameter and deformed. Then, when the mounting main body52is pressed into the attachment hole8huntil the circumferential edge portion of the attachment hole8his fitted inside the annular groove53, the mounting main body52elastically reverts to an original shape. Accordingly, the state where the circumferential edge portion of the attachment hole8his fitted into the annular groove53is maintained and a state where the mounting main body52is mounted to the attachment hole8his maintained.

The coupling portion54is an annular portion connecting the inner circumferential portion of the mounting main body52and the outer circumferential portion of the tube42. In this example, the coupling portion54connects the outer circumferential portion in the axis-direction middle portion of the tube42and the inner circumferential portion in the axis-direction middle portion of the mounting main body52. The middle portion of the coupling portion54between the inner circumferential portion and the outer circumferential portion is bent so as to project toward one axis-direction side of the tube42, and a posture of the tube42can be easily changed with respect to the mounting main body52.

In addition, an outer tube56having an inner diameter dimension larger than an outer diameter dimension of the tube42projects at a portion of the coupling portion54that is closer to the mounting main body52.

The grommet40does not need to have the configuration noted above. For example, the tube and the mounting main body may be coupled simply via a disk-shaped portion. The grommet may also have a configuration that combines a resin member and an elastic member.

An example of manufacturing the electric wire with grommet10is described.

First, the filler20is provided to the electric wire bundle12in which the plurality of electric wires13are bundled.

It is preferred that the arrangement of the filler20be configured as follows.

First, as shown inFIG. 4, a pair of alignment jigs60, formed with a slit S so as to enable the electric wire bundle12to be inserted therethrough, are prepared on a work table62standing with an interval therebetween. Then, each of the electric wires13of the electric wire bundle12is inserted through the slit S and arranged such that a location of the electric wire bundle12where the filler20is to be filled is arranged between the pair of alignment jigs60. Then, the plurality of electric wires13are arranged in parallel between the pair of alignment jigs60.

In this state, the filler20is supplied to each of the plurality of electric wires13between the pair of alignment jigs60. For example, a supply cartridge70provided with a nozzle74on a tip of a flexible resin tube72is prepared and the filler20squeezed out from the supply cartridge70is supplied so as to be applied to each of the plurality of electric wires13. At this time, the filler20is preferably applied evenly to the respective outer circumferences of the plurality of electric wires13. The filler20may be applied using a brush, a spatula, or the like.

After this, the plurality of electric wires13are removed from the pair of alignment jigs60. As shown inFIG. 5, the covering body30is wrapped around the location of the electric wire bundle12at which the filler20is supplied. At this time, in the extension direction of the electric wire bundle12, the location of the electric wire bundle12at which the filler20is filled is arranged as close as possible to the center of the covering body30. The covering body30should wrap around the electric wire bundle12at least once.

After this, as shown inFIG. 6, the fastening member34is wrapped around the outer circumference of the covering body30and the state in which the covering body30is wrapped around the electric wire bundle12is maintained. At this time, in the extension direction of the electric wire bundle12, portions at both end sides of the location of the electric wire bundle12at which the filler20is filled are fastened by the fastening member34. The fastening member34should be wrapped around at least once.

Then, while expanding the tube42of the grommet40, the electric wire bundle12is inserted through the tube42and the tube42elastically reverts to the original shape. Accordingly, the electric wire with grommet10is manufactured.

According to the water stop structure for an electric wire bundle18and the electric wire with grommet10configured in this way, the filler20is filled in the gaps between the plurality of electric wires13while maintaining fluidity and viscosity in at least a portion of the electric wire bundle12in the extension direction, and the covering body30covers the circumference of the portion of the electric wire bundle12filled with the filler20. Therefore, even when the electric wire bundle12is bent while mounting or after mounting the electric wire bundle12, for example, the filler20is unlikely to develop cracks or the like, and it is easy to maintain the state where the filler20fills the gaps between the plurality of electric wires13on the inner side of the covering body30. Accordingly, even when the electric wire bundle12is bent, the water stop performance between the plurality of electric wires13can be maintained as much as possible.

For example, as shown inFIG. 7, a case is considered where the electric wire with grommet10is mounted to the attachment hole8hthat is formed in the attachment panel8of the vehicle. Because the space to install various components in the vehicle is limited to some extent, a case is posited in which another portion80is arranged near the attachment hole8h. In this case, the portion of the electric wire bundle12extending from the grommet40may also need to be bent near the grommet40to be arranged so as to avoid the portion80. In this case, even when the electric wire bundle12is bent near the grommet40, the water stop performance between the plurality of electric wires13can be maintained as much as possible. Accordingly, the degree of freedom is improved in the arrangement layout of the electric wire bundle12and the arrangement layout of vehicle portions near the grommet40.

Also, even if a gap is created between a plurality of electric wire bundles12by pulling out a portion of the plurality of electric wires13completely or partially with respect to the others, the filler20flows down so as to fill the gap after a certain period of time has elapsed. In this respect also, the water stop performance between the plurality of electric wires13can be maintained as much as possible. Accordingly, when attaching the grommet40to the attachment panel8and the like, even when a gap is created between the electric wire bundles12with a force applied from outside at the location of the electric wire bundle12where the filler20is filled, the gap is blocked after a certain period of time has elapsed. Therefore, an operation restriction for mounting the grommet40to the attachment panel8can be reduced, which contributes to improving the attachment operation of the grommet40.

Also, when the plurality of electric wires13are bundled and the covering body30is wrapped around the circumference thereof, when the fastening member34is fastened around the circumference thereof, and when the outer circumference thereof is fastened by the tube42, in all these cases the filler20flows so as to fill the gaps between the plurality of the electric wires13. Also, even if a gap exists between the plurality of electric wires13immediately after the electric wire with grommet10is manufactured, after passing the certain period of time thereafter, the filler20having fluidity flows so as to fill the gap. Therefore, even when there is variation in the operation, the water stop structure for an electric wire bundle18having a stable water stop performance can be manufactured. Accordingly, a defective water stop structure for an electric wire bundle18is unlikely to be produced and water stop inspection for all objects is not necessary.

As the filler20, it is preferable to use grease having water repellency. A common grease that does not contain a surfactant or water-absorbing polymer has water repellency. Accordingly, even if a fine gap is created between the plurality of electric wires13, water infiltration due to a capillary state can be prevented.

When the grease configuring the filler20is applied to a test piece having the same material as the coating of the electric wire bundle12and a contact angle is measured by dropping water onto the same, the water repellency preferably has a contact angle of 80 degrees or more, and more preferably, the water repellency is at 80 degrees or more. In addition, when the surface of the applied grease is in contact with water, at the border line where the water is in contact with the surface of the grease, the contact angle is defined by an angle created by the water surface with respect to the surface of the grease.

When the fluidity of the filler20is too high, the filler20may flow out from the gaps between the plurality of electric wires13. In addition, when the viscosity of the filler20is too high, an operation of filling the filler20into a space between the plurality of electric wire bundles12(such as the application operation described above) becomes more difficult to perform. In view of this, the penetration of the filler20is preferred to be in a range of 200 to 400. More preferably, the penetration is 250 to 350. The penetration is “a worked penetration” defined by JIS K 2220.

In fact, when an operation of applying the filler20with the penetration within the 200 to 400 range to the plurality of electric wires13is carried out, the operation is confirmed to be easy. In addition, according to an air pressure difference between the engine compartment and the cabin of the vehicle, an air pressure difference is provided before and after the location where the filler20is filled in the electric wire bundle12, and when it is confirmed that no filler20is removed from the gaps between the plurality of electric wires13, it confirms that there are no particular issues.

The viscosity and fluidity of the filler20is preferably maintained during a period up to when the water stop structure for an electric wire bundle is mounted to a vehicle or the like which is a mounting target, and also after being mounted to the vehicle or the like which is the mounting target.

In view of this, an oil separation degree of the filler20after passing 24 hours at 100° C. is preferably at 0% (significant digit is one digit). The oil separation degree is defined by JIS K 2220.

In addition, when the filler20is left in a constant temperature bath at 50° C. for 30 days, the filler is preferably not separated.

Accordingly, in a state where the water stop structure for an electric wire bundle18is assembled to the vehicle, the filler20can keep the desired viscosity and fluidity noted above, and thereby the water stop performance can be maintained. Also, when the filler20is applied to the electric wire bundle12and the like, it is possible to perform the application operation or the like without, for example, stirring a substance injected into a container such as the supply cartridge70, and operability is excellent.

Also, in order to maintain the viscosity and fluidity of the filler20during the period when the water stop structure for an electric wire bundle is mounted to the target, an evaporation amount of the filler20after passing 22 hours at 100° C. is preferably at or below 0.1% (significant digit is two digits). The amount of evaporation is defined by JIS K 2220.

Accordingly, in the state where the water stop structure for an electric wire bundle18is assembled to the vehicle, the filler20can keep the desired viscosity and fluidity, and thereby the water stop performance can be maintained.

As the filler20satisfying the preferable ranges for each of the penetration, oil separation degree, and amount of evaporation, Molykote G (Molykote is a registered trademark) manufactured by Dow Corning Toray Co., Ltd., can be presented as an example, and product number G-1057 can be given among them.

Also, in the water stop structure for an electric wire bundle18, the fastening member34is provided respectively to a portion in the extension direction of the electric wire bundle12at both end sides of the portion of the electric wire bundle12filled with the filler20. Therefore, in the portions at both end sides of the portion of the electric wire bundle12filled with the filler20, the gaps between the electric wires13become small and the filler20is prevented from passing through the gaps between the electric wires13and escaping to the outside. In this respect also, stopping water between the electric wire bundles12can be maintained as much as possible.

In addition, the water stop structure for an electric wire bundle18is inserted through the tube42of the grommet40. The grommet40is mounted to the attachment hole8hformed in the attachment panel8and the portion of the electric wire bundle12filled with the filler20is inserted through the tube42of the grommet40. Accordingly, water can be stopped by the grommet40on the two sides of the attachment panel8.

In the embodiment described above, a description has been given using an example where the water stop structure for an electric wire bundle18is inserted through the grommet40; however, the water stop structure is also applicable in other locations. For example, a water stop structure incorporating a filler and a covering body may be configured in an electric wire bundle in the extension-direction middle portion of a wire harness and an electric wire bundle on the near side of a connector at the end portion of the wire harness. Accordingly, water movement through the wire harness is prevented.

Each configuration described in each of the above embodiments and each of the modifications can be combined as appropriate so long as they do not contradict each other.

In the above, the present invention is described in detail. However, the above description is, in all aspects, for exemplary purposes and the present invention is not limited thereto. Numerous modifications not given as examples are understood to be conceivable without departing from the scope of the present invention.

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