Patent Description:
Such a structure is known from <CIT> which refers to a connector comprising a primary resin-molded member and a secondary resin-molded member and a first sealing material disposed between the primary resin-molded member, the secondary resin-molded member and a covering material of a cable. A second sealing member is disposed between the end of secondary resin-molded member, the covering material of a cable and a protection tape. The first and second sealing members are two distinct seals separated from one another. <CIT> refers to an integrally molded connector including an electric wire with a core part and cover part. A terminal is connected to the core part of the electric wire and a covering member is formed through injection molding. An elastic resin which provides for a sealing function is injection molded around a connection part between the terminal and the core part of the electric wire and a portion of the electric wire. The elastic resin has a portion extending out of the covering member. Holes are provided in the elastic resin so that part of the resin can flow into those and provide for an engagement. <CIT> refers to a waterproof connector having a waterproofing part that is formed by injection with hot-melt material. One portion of the waterproofing part surrounds a wire and a part of the terminals within a housing. This portion of that waterproofing part fills a recess in the housing and has a smaller diameter than a flange portion of the waterproofing part that is located outside the housing. A further related art waterproof structure is configured to provide waterproof property between a mounting hole of an object to which an electric wire is mounted and the electric wire to be inserted into the mounting hole (see, e.g., <CIT>). The connector includes a seal portion and a housing. The seal portion is formed of an insulating elastic material that integrally covers an insulation of the electric wire and the housing is formed of an insulating resin having higher rigidity than the elastic material that integrally covers the seal portion at an end portion of the electric wire. The seal portion formed of the elastic material is primarily molded on the insulation of the electric wire. The housing formed of the insulating resin is secondarily molded to cover the seal portion. In the connector, an elastic material is used for the primarily molded seal portion, so that a waterproof function is imparted and stress during bending of the electric wire is reduced.

As described above, in the waterproof structure of the connector in the related art, a cylindrical elastic material is provided to be in contact with an outer peripheral surface of an electric wire insulation (hereinafter simply referred to as "insulation") of the electric wire. An elastomer or the like for ensuring water tightness is preferably used for the elastic material.

However, in the waterproof structure in the related art, due to a difference in linear expansion coefficient of the insulation, the elastomer and the housing material, a part of the elastomer that is overlapped by the housing may be pushed out of the housing. Therefore, in the waterproof structure in the related art, an appearance defect, wire breakage or a decrease in waterproof function caused by wrinkles may occur.

The present invention provides a waterproof structure according to claim <NUM> by which the appearance defect, the wire breakage and the decrease in waterproof function caused by wrinkles can be prevented.

<FIG> is a perspective view of a connector <NUM> having a waterproof structure according to an embodiment not covered by the present invention, and <FIG> is a perspective view of the connector <NUM> in <FIG> in which a housing <NUM> is omitted. The waterproof structure according to the embodiment is applied to a so-called over-molded connector in which, as shown in <FIG>, a terminal <NUM> is connected to a conductor <NUM> of an electric wire <NUM>, and an end portion of the electric wire <NUM> and a part of the terminal <NUM>, which are connection portions where the conductor <NUM> and the terminal <NUM> are connected to each other, are covered by an insulating resin molded product.

In the connector <NUM>, the terminal <NUM> is conductively connected to the end portion of the electric wire <NUM> that can be obtained by covering the conductor <NUM> by the insulation <NUM>. The electric wire <NUM> is to be inserted through a mounting hole of a mounting portion (not shown). The electric wire <NUM> may be an electric wire that can be obtained by covering the conductor <NUM> only by the insulation <NUM> or may be a shielded electric wire in which an inner insulating cover covering the conductor <NUM> is covered by a shielding member such as a metal braid and the shielding member is further covered by a jacket.

The terminal <NUM> is connected and fixed to the conductor <NUM>, the conductor <NUM> being exposed at the end portion of the electric wire <NUM>. The connection structure between the terminal <NUM> and the conductor <NUM> may be any one of a crimping structure, a pressure welding structure, a welding structure, a brazing structure, or the like. In the embodiment, the terminal <NUM> is exemplified to be a flat terminal in which an electric contact portion <NUM> is a male tab type, but the terminal <NUM> may be a round terminal, a Y-shaped terminal, or the like or may be a female terminal having a box-shaped electric contact portion.

The waterproof structure according to the embodiment is configured as a connector <NUM> in which an insulating elastic member such as a thermoplastic elastomer is primarily molded as a first seal portion <NUM> and a second seal portion <NUM> on the outer periphery of the electric wire <NUM>, and then an insulating resin such as a thermoplastic resin is secondarily molded as a housing <NUM> on the first seal portion <NUM> and a part of the terminal <NUM>. At this time, the second seal portion <NUM> is molded contiguously with one end portion of the housing <NUM>.

In the connector <NUM>, the terminal <NUM> is conductively connected to the conductor <NUM> of the electric wire <NUM> at the end portion of the electric wire <NUM>. A connection portion <NUM> of the terminal <NUM>, at which the terminal <NUM> is connected to the conductor <NUM>, is covered by the housing <NUM>. The electric contact portion <NUM> on a side opposite to the connection portion <NUM> projects to the outside of the housing <NUM>.

The housing <NUM> is formed of an insulating resin (for example, PBT) having higher rigidity than the elastic material forming the first seal portion <NUM> or the second seal portion <NUM>. The housing <NUM> integrally covers a part of the first seal portion <NUM> at the end portion of the electric wire <NUM> and the connection portion <NUM> of the terminal <NUM>. The housing <NUM> covers an entirety of the first seal portion <NUM>. The housing <NUM> includes a flange portion <NUM> that protrudes radially outward at a substantially central portion of the housing <NUM> in a direction along the electric wire <NUM>. The flange portion <NUM> is to abut the mounting portion including the mounting hole. A peripheral groove <NUM> is formed on an outer periphery of the housing <NUM> at a position closer to the terminal side than the flange portion <NUM>. An annular elastic seal member (not shown) is mounted on the peripheral groove <NUM>.

As shown in <FIG>, the primarily molded first seal portion <NUM> and second seal portion <NUM> are annular bodies having different outer diameters and separated by a predetermined distance, and are in contact with an outer peripheral surface of the insulation <NUM>. In the embodiment, an outer diameter of the second seal portion <NUM> is formed to be larger than an outer diameter of the first seal portion <NUM>. The second seal portion <NUM> functions as a seal portion that water-tightly seals a gap between the housing <NUM> and the insulation <NUM>. Also the second seal portion <NUM> serves as a portion (abutted portion) which a molded burr cutter is to abut.

In the secondary molding using an injection molding machine, when the housing <NUM> is molded, it is necessary to prevent occurrence of burrs caused by leakage of molten resin when the molten resin is press-fitted into a mold cavity. For this reason, the second seal portion <NUM> servers as the abutting portion. The burr cutter includes a plurality of mountainous sharp tip end portions to sandwich the electric wire <NUM>. Therefore, in a case where the housing <NUM> is directly formed on the outer periphery of the electric wire <NUM>, the insulation <NUM> may be damaged when the electric wire <NUM> is arranged in the mold. In the waterproof structure of the embodiment, since the burr cutter provided in a mold for secondary molding is to be in contact with the outer periphery of the second seal portion <NUM> molded by the primary molding, the insulation <NUM> of the electric wire <NUM> is not damaged by the burr cutter.

<FIG> is a longitudinal cross-sectional view of the connector <NUM> shown in <FIG>, and <FIG> is a main part enlarged view of the first seal portion <NUM> and the second seal portion <NUM> in <FIG>. In the waterproof structure according to the embodiment, an annular first seal portion <NUM> that is primarily molded by an elastic member covers the electric wire <NUM>. The first seal portion <NUM> is embedded in the housing <NUM>. That is, the first seal portion <NUM> is an annular embedded portion. At one end portion of the housing <NUM>, the second seal portion <NUM> made of the same elastic member as the first seal portion <NUM> is molded at the same time as the primary molding of the first seal portion <NUM>. The second seal portion <NUM> is provided contiguously with the one end portion of the housing <NUM>.

In the embodiment, the first seal portion <NUM> and the second seal portion <NUM> are formed of the same material. The material can be, for example, an elastomer.

In the embodiment, a width of the one end portion of the housing <NUM> in a radial direction of the housing <NUM> and a width of the second seal portion <NUM> in a radial direction of the second seal portion <NUM> are formed substantially the same. In other words, the one end portion of the housing <NUM> and the second seal portion <NUM> have a substantially same outer diameter. Therefore, the one end portion of the housing <NUM> formed in a cylindrical shape around the electric wire <NUM> is contiguous with the second seal portion <NUM> without a step. The one end portion of the housing <NUM> has the same outer diameter as the second seal portion <NUM>.

In the waterproof structure according to the embodiment, at least one of the first seal portion <NUM> and the second seal portion <NUM> may be a heat-shrinkable tube or a solidified adhesive. If the first seal portion <NUM> and the second seal portion <NUM> are formed of a heat-shrinkable tube or an adhesive, primary molding performed by a mold can be omitted. In this case, in the waterproof structure according to the embodiment, the housing <NUM> is molded after the first seal portion <NUM> and the second seal portion <NUM> are formed by a heat-shrinkable tube or an adhesive.

Next, operation of the above configuration will be described. Before describing the operation of the waterproof structure according to the embodiment, operation of a waterproof structure in the related art will be described with reference to <FIG> and <FIG>.

As shown in <FIG>, in the waterproof structure for waterproofing between a mounting hole and an electric wire inserted through the mounting hole, a cylindrical elastic member is provided in contact with the outer periphery of the insulation <NUM>. The elastic member serves as a seal portion <NUM> for ensuring water tightness. An example of a material of the elastic member can include an elastomer. The seal portion <NUM> is primarily molded on the outer periphery of the insulation <NUM>. A housing <NUM> is further secondarily molded on an outer periphery of the seal portion <NUM> and is in close contact therewith. The housing <NUM> is made of a material, for example, polybutylene terephthalate (PBT) having higher rigidity than that of the seal portion <NUM>. That is, between the electric wire <NUM> and the housing <NUM>, the conductor <NUM> of the electric wire <NUM>, the insulation <NUM>, the seal portion <NUM>, and the housing <NUM> are laminated radially outward from a central side. Here, the cylindrical seal portion <NUM> is provided in an annular groove portion <NUM> (with reference to <FIG>) of the housing <NUM> in which one end portion in an axial direction is closed and the other end portion is opened. Therefore, an end portion (a right end portion in <FIG>) of the seal portion <NUM> extends from the housing <NUM> to the outside.

This type of waterproof structure to be mounted on a vehicle is exposed to a large temperature change. The temperature change is, for example, in a range from -<NUM> to <NUM>. In the range from -<NUM> to <NUM>, linear expansion coefficients of the members forming the respective structural portions are as follows in a descending order: the conductor <NUM> (copper alloy or aluminum alloy), the insulation <NUM> (cross-linked polyethylene), the first seal portion <NUM> (elastomer), and the housing <NUM> (PBT).

The waterproof structure in the related art may behave such that the appearance and the waterproof performance are degraded due to a temperature change since the members having different linear expansion coefficients are in contact with each other in a laminated structure. By each part getting expanded and contracted repeatedly, the members move and the movement (displacement) of the insulation <NUM> is larger than other members in the above-described laminated structure, excluding the conductor <NUM> considering the conductor <NUM> does not directly affect the appearance and waterproof performance.

<FIG> are schematic views illustrating the operation of the waterproof structure in the related art. <FIG> is a schematic view illustrating behavior during thermal expansion, and <FIG> is a schematic view illustrating behavior during thermal contraction. <FIG> is a schematic view of the waterproof structure in which the insulation <NUM> is deformed due to thermal expansion and contraction. In the seal portion <NUM> in the laminated structure, an interface with the insulation <NUM> follows the movement of the insulation <NUM> due to the temperature change. Meanwhile, in the seal portion <NUM> in the laminated structure, due to repeated thermal expansion and contraction, as shown in <FIG>, a volume in a thickness direction outside the interface is pushed out of the housing <NUM> from the annular groove portion <NUM> which overlaps the seal portion <NUM>, to form a bulging portion <NUM>. For this reason, as shown in <FIG>, after the insulation <NUM> that is in contact with the seal portion <NUM> and has a greater tendency to move than other members is moved due to thermal contraction, the bulging portion <NUM> is unlikely to return to an original position thereof. Therefore, as shown in <FIG>, when the expansion and contraction of the seal portion <NUM> is repeated, wrinkles and deformation occur in the insulation <NUM>. As a result, in the waterproof structure in the related art, the appearance defect or the decrease in waterproof function may occur by the deformation of the insulation <NUM>.

Therefore, in the waterproof structure of the embodiment, the first seal portion <NUM> made of an elastic member covering the electric wire <NUM> is covered by the housing <NUM> formed of an insulating resin having higher rigidity than the elastic member. The housing <NUM> embeds the first seal portion <NUM> in a molded body by covering the first seal portion <NUM> together with the electric wire <NUM>. That is, the first seal portion <NUM> is an annular embedded portion inside the housing <NUM>. The annular second seal portion <NUM> made of an elastic member is contiguously formed at the one end portion of the housing <NUM> that covers the first seal portion <NUM>.

Accordingly, since the first seal portion <NUM> is an annular embedded portion inside the housing, the first seal portion <NUM> does not protrude out of the housing <NUM> despite a difference in linear expansion coefficient, with respect to a normal structure in which one end portion of the tubular seal portion extends to the outside from the annular groove <NUM> which is an overlapping part of the housing <NUM>.

In the waterproof structure of the embodiment, due to the second seal portion <NUM> provided at the one end portion of the housing <NUM>, damage to the electric wire <NUM> caused by the sandwiching of a mold matching portion can be prevented.

Further, in the waterproof structure of the embodiment, since the second seal portion <NUM> that is made of an elastic member and is contiguous with the housing <NUM> covers the electric wire <NUM>, the stress acting on the electric wire <NUM> when the electric wire <NUM> led out from a rear end of the housing <NUM> is bent can be reduced by the deformation of the second seal portion <NUM>.

The second seal portion <NUM> contiguous with one end portion of the housing <NUM> is an elastic member, so that the second seal portion <NUM> can water-tightly seal a gap between the housing <NUM> and the electric wire <NUM>. That is, the waterproof structure of the configuration can be configured as a double waterproof structure of the housing <NUM> and the electric wire <NUM> by providing both the first seal portion <NUM> and the second seal portion <NUM>.

Accordingly, in the waterproof structure of the embodiment, the protrusion of the first seal portion <NUM> is restricted, and the deformation of the insulation <NUM> in contact with the first seal portion <NUM> is reduced, so that the appearance defect and the decrease in waterproof function can be prevented.

In the waterproof structure of the embodiment, the first seal portion <NUM> and the second seal portion <NUM> are both formed of the elastic member, so that the first seal portion <NUM> and the second seal portion <NUM> are primary molded at the same time using the same mold and the same molding resin material. Accordingly, the manufacturing process can be simplified.

In the waterproof structure of the embodiment, the height at which the outer peripheral surface of the one end portion of the housing <NUM> is provided and the height at which the outer peripheral surface of the second seal portion <NUM> is provided are formed substantially the same with each other. Therefore, a joint area in the height direction (distance in the radial direction of the electric wire <NUM>) between the housing <NUM> and the second seal portion <NUM> can be maximized. Accordingly, the housing <NUM> and the second seal portion <NUM> can be hardly separated. As a result, it is possible to obtain a molded product more excellent in surface appearance.

In the waterproof structure of the embodiment, the primary molding step using a mold can be omitted by making both the first seal portion <NUM> and the second seal portion <NUM> with a heat-shrinkable tube or a solidified adhesive. Accordingly, the mold cost for the primary molding is eliminated. When either one of the first seal portion <NUM> or the second seal portion <NUM> is formed into a heat-shrinkable tube or a solidified adhesive, the mold cost for the primary molding can be simplified.

Next, a waterproof structure according to another embodiment not covered by the present invention will be described. <FIG> is a perspective view of a connector <NUM> having a waterproof structure according to the another embodiment not covered by the present invention, and <FIG> is a perspective view of the connector <NUM> in <FIG> in which a housing <NUM> is omitted. In the another embodiment, the same members as those described in the above embodiment are denoted by the same reference numerals, and repetitive descriptions thereof will be omitted. In the waterproof structure of the another embodiment, at the end portion of the electric wire <NUM>, the terminal <NUM> is conductively connected to the conductor <NUM> of the electric wire <NUM> from which the insulation <NUM> is stripped off. The housing <NUM> covers the electric wires <NUM> excluding the connection portions <NUM> at which the respective terminals <NUM> and conductors <NUM> are connected to each other.

The connector <NUM> is provided for a plurality (two in the embodiment) of the electric wires <NUM> in which the terminals <NUM> are conductively connected to the conductors <NUM> respectively. The housing <NUM> integrally covers a gap between the two electric wires <NUM>. That is, the gap serves as a connection portion <NUM> that is secondarily molded by an insulating resin by which the housing <NUM> is molded. The housing <NUM> includes a flange portion <NUM> that protrudes radially outward at a substantially central portion of the housing <NUM> in a direction along the electric wire <NUM>. The flange portion <NUM> is to abut the mounting portion including the mounting hole.

<FIG> is a plan view of the connector <NUM> shown in <FIG>, and <FIG> is a cross-sectional view taken along a line A-A in <FIG>. In the waterproof structure according to the another embodiment, a part of the second seal portion <NUM> is covered by the housing <NUM>.

In the connector <NUM> according to the another embodiment, the peripheral groove <NUM> is formed on an outer periphery of the housing <NUM> at a position closer to the terminal <NUM> than the flange portion <NUM>. An annular elastic seal member <NUM> to be in contact with an inner peripheral wall of the mounting portion is mounted on the peripheral groove <NUM>. The elastic seal member <NUM> water-tightly seals a gap between the housing <NUM> and the inner peripheral wall of the mounting portion. An annular groove portion <NUM> is formed in the housing <NUM> on an end surface opposite to the first seal portion <NUM>. A third seal portion <NUM> made of an elastic member is provided in the annular groove portion <NUM>. The third seal portion <NUM> can be formed by primary molding similarly to the first seal portion <NUM>. The third seal portion <NUM> water-tightly seals a gap between the insulation <NUM> and the housing <NUM> on the end surface of the housing <NUM> opposite to the first seal portion <NUM>.

In the waterproof structure according to the another embodiment, since a part of the second seal portion <NUM> is embedded in and covered by the housing <NUM>, a large joint surface between the housing <NUM> and the second seal portion <NUM> can be secured. Since it is possible to increase the joint surface between the housing <NUM> and the second seal portion <NUM> (that is, the joint surface between an outer peripheral surface of the insulation <NUM> and an inner peripheral surface of the housing <NUM> being in contact with each other) in which a separation direction is a shear direction, the joining strength between the housing <NUM> and the second seal portion <NUM> can be increased as compared with a joint structure only with end surfaces being in contact with each other.

In the waterproof structure of the another embodiment, the terminal <NUM> is conductively connected to the conductor <NUM> that is exposed by removing the insulation <NUM> at the end portion of the electric wire <NUM>. The housing <NUM> covers the electric wires <NUM> excluding the connection portions <NUM> of the respective terminals <NUM> and conductors <NUM>. That is, the housing <NUM> is provided at a position of the electric wire <NUM> in the middle of the electric wire <NUM>, the position being away from the terminal <NUM> that is conductively connected to the end portion of the electric wire <NUM>. The annular elastic seal member <NUM> is mounted on the peripheral groove <NUM> that is on the outer periphery of the housing <NUM>. The elastic seal member <NUM> water-tightly seals a gap between the housing <NUM> and the mounting hole of the mounting portion. Therefore, in the waterproof structure of the another embodiment, due to the operation described above, the electric wire <NUM> in which the terminal <NUM> is conductively connected with the end portion of the electric wire <NUM> can be passed through the mounting portion in a water-tight structure, while preventing the appearance defect of the insulation <NUM> and the decrease in waterproof function.

Next, modifications of the waterproof structure according to the above embodiment and the above another embodiment will be described. <FIG> is a longitudinal cross-sectional view of a first seal portion <NUM> and a second seal portion <NUM>, and <FIG> is a longitudinal cross-sectional view of the first seal portion <NUM> and a second seal portion <NUM> according to an embodiment of the present invention. In the waterproof structure as shown in <FIG>, a part of the second seal portion <NUM> is covered by the housing <NUM>. In the embodiment of <FIG>, a part of the second seal portion <NUM> that is overlapped by the housing <NUM> is formed to be smaller in outer diameter than the other part.

In the waterproof structure according to <FIG>, since a part of the second seal portion <NUM> is embedded in and covered by the housing <NUM>, a large joint surface between the housing <NUM> and the second seal portion <NUM> can be secured. Since it is possible to increase the joint surface between the housing <NUM> and the second seal portion <NUM> (that is, the joint surface between an outer peripheral surface of the insulation <NUM> and an inner peripheral surface of the housing <NUM> being in contact with each other) in which a separation direction is a shear direction, the joining strength between the housing <NUM> and the second seal portion <NUM> can be increased as compared with a joint structure only with end surfaces being in contact with each other.

A part of the second seal portion <NUM> which is overlapped by the housing <NUM> is a thin-wall annular portion <NUM>, and the other part is a thick-wall annular portion <NUM>. Accordingly, as compared with a structure in which inner diameter and outer diameter of the second seal portion <NUM>, throughout an entire longitudinal direction of the second seal portion <NUM>, are the same, a wall thickness (amount) of the second seal portion <NUM> in the annular groove portion <NUM> of the housing <NUM> is smaller than that of the thick-wall annular portion <NUM>, so that an amount to be pushed out of the housing <NUM> is reduced during thermal expansion. Accordingly, the displacement (residual deformation) of the second seal portion <NUM> caused by thermal expansion and thermal contraction is prevented. As a result, the insulation <NUM> that is in contact with the second seal portion <NUM> is less deformed, and the appearance defect and the decrease in waterproof function are prevented.

In the waterproof structure according to the an embodiment of the present invention, as shown in <FIG>, at least a part of the second seal portion <NUM> that is overlapped by the housing <NUM> includes a tapered surface <NUM> whose outer diameter gradually decreases toward the housing <NUM>.

The tapered surface <NUM> can be set to a convex curved surface. The tapered surface <NUM> may be set to a flat inclined surface. In addition, the tapered surface <NUM> can also be set to a concave curved surface.

In the waterproof structure according to the embodiment, the second seal portion <NUM> includes the tapered surface <NUM>, and thus a volume of second seal portion <NUM> that is overlapped by the housing <NUM> gradually decreases toward the housing <NUM>. In other words, the volume of the second seal portion <NUM> gradually increases in a direction away from the housing <NUM>. Even when the second seal portion <NUM> is pushed by the above-described operation, since the volume of the second seal portion <NUM> in the pushing direction side is increased, a push-out amount of the second seal portion <NUM>, for which the second seal portion <NUM> has been pushed out of the housing <NUM> during thermal expansion, is decreased.

In the waterproof structure according to the above embodiment of <FIG>, the second seal portion <NUM> together with the insulation <NUM> is drawn in a direction toward the housing <NUM> during thermal contraction. The second seal portion <NUM> enters the annular groove portion <NUM> of the housing <NUM> due to the displacement in the drawing direction. At this time, since the second seal portion <NUM> is in contact with an inner peripheral wall of the housing <NUM> with the tapered surface <NUM> that is reduced in diameter toward a direction in which the second seal portion <NUM> enters the annular groove portion <NUM>, the insulation <NUM> is pressed by a reaction force from the housing <NUM>. Accordingly, the housing <NUM> and the second seal portion <NUM>, the second seal portion <NUM> and the insulation <NUM>, respectively contact with each other tightly by virtue of the reaction force from the housing <NUM>.

Due to the operation, in the waterproof structure of the above embodiment of <FIG>, the displacement of the second seal portion <NUM> caused by thermal expansion and thermal contraction is prevented. As a result, the insulation <NUM> that is in contact with the second seal portion <NUM> is less deformed, and the appearance defect and the decrease in waterproof function are prevented.

Therefore, according to the waterproof structures of the respective embodiments described above, the appearance defect and wire breakage of the electric wire <NUM> and the decrease in waterproof function caused by wrinkles of the insulation <NUM> can be prevented.

According to the waterproof structure configured as above, since the first seal portion is an annular portion embedded inside the housing, the first seal portion does not protrude out of the housing due to a difference in linear expansion coefficient, compared with a structure in which one end portion of the tubular seal portion extends to the outside from the annular groove (which is an overlapping part with the first seal portion) of the housing <NUM>. In the waterproof structure having the configuration, by virtue of the second seal portion provided at one end portion of the housing, damage to the electric wire caused by the electric wire being sandwiched by molds can be prevented. Further, in the waterproof structure of the embodiment, since the second seal portion that is made of an elastic member and is contiguous with the housing covers the electric wire, the stress acting on the electric wire when the electric wire being led out from a rear end of the housing is bent can be reduced by the second seal portion being deformed. Since the second seal portion being contiguous with one end portion of the housing is an elastic member, the second seal portion can water-tightly seal a gap between the housing and the electric wire. That is, the waterproof structure of the configuration can be configured as a double waterproof structure between the housing and the electric wire by providing both the first seal portion and the second seal portion. Accordingly, in the waterproof structure having the configuration, the protrusion of the first seal portion is restricted, and the deformation of the insulation being in contact with the first seal portion is reduced. As a result, the appearance defect and the decrease in waterproof function can be prevented.

According to the waterproof structure configured as above, since the first seal portion and the second seal portion are both formed of the elastic member, the first seal portion and the second seal portion can be primary molded at the same time using the same mold and the same molding resin material. Accordingly, the manufacturing process can be simplified.

According to the waterproof structure configured as above, a joint area in the height direction (distance in the radial direction of the electric wire) between the housing and the second seal portion can be maximized, which makes it difficult to separate the housing and the second seal portion. Accordingly, the double waterproof structure can be more reliable.

According to the waterproof structure configured as above, since a part of the second seal portion is embedded in and covered by the housing, a surface area (joint surface) with which the housing and the second seal portion contact with each other can be largely secured. This structural configuration increases the joint surface between the housing and the second seal portion (that is, the joint surface with which an outer peripheral surface of the insulation and an inner peripheral surface of the housing contact with each other) in which a separation direction is a shear direction, the joint strength between the housing and the second seal portion can be increased as compared with a joint structure only with end surfaces being in contact with each other.

According to the waterproof structure configured as above, the primary molding step using a mold can be omitted by setting both the first seal portion and the second seal portion into a heat-shrinkable tube or a solidified adhesive. Accordingly, the mold cost for the primary molding is eliminated. When either one of the first seal portion and the second seal portion is formed into a heat-shrinkable tube or a solidified adhesive, the mold cost for the primary molding can also be simplified.

Claim 1:
A waterproof structure comprising:
a first seal portion (<NUM>) covering around an electric wire (<NUM>) to be inserted into a mounting hole of an object to which the electric wire (<NUM>) is mounted, the electric wire (<NUM>) having a conductor (<NUM>) and an insulation (<NUM>) covering the conductor (<NUM>), and the first seal portion (<NUM>) being elastic and electrically insulative;
a housing (<NUM>) provided at an end portion of the electric wire (<NUM>), the housing (<NUM>) covering the first seal portion (<NUM>), the housing (<NUM>) being made of an insulating resin having higher rigidity than the first seal portion (<NUM>); and
a second seal portion (<NUM>) covering around the electric wire (<NUM>) being provided contiguously with an end portion of the housing (<NUM>) and being elastic and electrically insulative, wherein
the housing (<NUM>) covers an entirety of the first seal portion (<NUM>), characterized in that a part of the second seal portion (<NUM>) is covered by the housing (<NUM>), the part of the second seal portion (<NUM>) that is overlapped by the housing (<NUM>) is formed to be smaller in outer diameter than the other part of the second seal portion (<NUM>), and the part of the second seal portion (<NUM>) that is overlapped by the housing (<NUM>) is shorter in length than the other part of the second seal portion (<NUM>), and
the part of the second seal portion (<NUM>) that is overlapped by the housing (<NUM>) includes a tapered surface (<NUM>) whose outer diameter gradually decreases toward the first seal portion (<NUM>) of the housing (<NUM>).