JP7706892B2 - Heater unit and vehicle seat - Google Patents

Description

The present invention relates to a heater unit that can be suitably used in electric blankets, electric carpets, car seat heaters, etc., and that has excellent breathability and mechanical strength.

Conventionally, heater units that are installed in vehicle seats and used as car seat heaters include, for example, those in which a cord-shaped heater with a heat-sealing portion is wired in a serpentine pattern on a base material, and the base material and the heat-sealing portion are bonded and fixed by heat fusion under heat and pressure (see, for example, Patent Document 1). In recent years, vehicle seats incorporating air conditioning units have been put into practical use to further improve the comfort of the vehicle interior environment. Specifically, a known example is one in which the heater unit and seat skin are made breathable, and air is blown toward the skin side through ventilation passages formed inside the seat, so that air is blown out from the surface of the vehicle seat (see, for example, Patent Document 2).

Heater units applied to vehicle seats incorporating such air conditioning devices are required to have particularly good breathability. For this reason, it is known to improve breathability by using, as the base material for the heater unit, a base material with multiple through holes, a base material made of a material with good breathability such as spunbond nonwoven fabric or spunlace nonwoven fabric, or a base material with a mesh structure (see Patent Documents 3 to 7).

Patent No. 4202071: Kurabe Patent No. 4999455: Kurabe Patent No. 3991750: Matsushita Electric Industrial Co., Ltd. JP 2005-285602 A: Matsushita Electric Industrial Co., Ltd. JP Patent Publication No. 8-507404: Scandomec JP2015-74375A: TS Tech Patent No. 6636825: Kurabe

However, in the base materials of the heater units described in Patent Documents 3 to 6, the tradeoff for breathability is a significant decrease in mechanical strength. In particular, in heater units applied to vehicle seats, repeated loads are applied when the driver sits and leaves the seat, but sufficient characteristics have not been obtained to prevent deformation or breakage even under such loads. Furthermore, in base materials formed with multiple through holes, breathability is only slightly improved, and further improvement in breathability is required.

The heater unit described in Patent Document 7 solves the problems of the heater units described in Patent Documents 3 to 6. However, there is a need to further improve breathability, and there is a demand to reduce the density (basis weight) of the nonwoven fabric. This reduces the mechanical strength and rigidity of the base material, making it more susceptible to breakage and deformation. If the base material is deformed, for example, it becomes difficult to place the heater unit on a vehicle seat, and the heater unit may end up being placed in a location not intended by the design. This has created a need to further reinforce the mechanical strength and rigidity of the heater unit.

The present invention was made to solve these problems with the conventional technology, and its purpose is to provide a heater unit that has excellent breathability and mechanical strength.

In order to achieve the above-mentioned object, the heater unit of the present invention has a base material and a cord-like heater, and the cord-like heater is disposed and fixed on the base material, the base material being formed by combining fiber yarn and nonwoven fabric arranged in a substantially planar shape, and the cord-like heater is fixed in direct contact with the fiber yarn.
It is also conceivable that a heat-sealed portion is formed on the outermost layer of the cord-shaped heater, and the heat-sealed portion is fixed to the nonwoven fabric and the fiber yarn by heat fusion.
It is also contemplated that the fiber threads are woven, knitted, or overlapped with strands of yarns in different directions, and have openings larger than the apparent diameter of the fiber threads.
It is also conceivable that the base material is made of a fiber yarn and a pair of nonwoven fabrics, and the fiber yarn is sandwiched between the pair of nonwoven fabrics.Furthermore, the vehicle seat according to the present invention has a seat cover and a seat pad, and the heater unit is disposed between the seat cover and the seat pad.

Generally, in order to improve the breathability, it is effective to reduce the amount of fibers per unit area of the substrate, but this also results in a significant decrease in the mechanical strength and rigidity of the substrate. However, with the heater unit according to the present invention, tensile strength is obtained by the fiber threads arranged in a substantially planar shape. Therefore, even a substrate with improved breathability has excellent mechanical strength.
Furthermore, since the heat-sealed portion and the fiber yarn are directly fixed to each other, it is possible to prevent the cord-shaped heater from peeling off due to the fibers coming loose from the nonwoven fabric. Also, since the cord-shaped heater and the fiber yarn are firmly integrated, it has the effect of making the heater unit less likely to deform.

FIG. 2 is a diagram showing an embodiment of the present invention, and is a plan view showing a configuration of a heater unit. FIG. 2 is a partially cutaway perspective view showing the configuration of a base material according to an embodiment of the present invention. FIG. 1 is a diagram showing an embodiment of the present invention, and is a partially cutaway side view showing the configuration of a cord-shaped heater. FIG. 1 is a diagram showing an embodiment of the present invention, illustrating the configuration of a hot press heater manufacturing apparatus. FIG. 1 is a diagram showing an embodiment of the present invention, and is a partial perspective view showing how cord-shaped heaters are arranged in a predetermined pattern shape. FIG. 2 is an enlarged plan view showing a portion of a heater unit through a base material according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a portion of a heater unit according to an embodiment of the present invention. FIG. 1 is a perspective view showing an embodiment of the present invention, with a part cut away, illustrating a heater unit embedded in a vehicle seat. FIG. 11 is a diagram showing another embodiment of the present invention, and is a partially cutaway side view showing the configuration of a cord-shaped heater. FIG. 11 is a diagram showing another embodiment of the present invention, and is a partially cutaway side view showing the configuration of a cord-shaped heater. FIG. 11 is a diagram showing another embodiment of the present invention, and is a partially cutaway side view showing the configuration of a cord-shaped heater. FIG. 11 is a diagram showing another embodiment of the present invention, and is a partially cutaway side view showing the configuration of a cord-shaped heater. FIG. 13 is a partially cutaway perspective view showing another embodiment of the substrate according to the present invention, illustrating a configuration of the substrate in another form. 1 is a photograph showing an embodiment of the present invention, which is an enlarged photograph of a main part of a heater unit. 1 is a photograph showing an embodiment of the present invention, which is an enlarged photograph of a cross section of a main part of a heater unit.

The following describes embodiments of the present invention with reference to the drawings. These embodiments show examples in which the present invention is applied to a vehicle seat heater.

First, the configuration of the cord-shaped heater 10 in the present embodiment 1 will be described. The cord-shaped heater 10 in the present embodiment is configured as shown in FIG. 3. First, there is a heater core 3 made of an aromatic polyamide fiber bundle with an outer diameter of about 0.2 mm, and six conductor wires 5a made of tin-plated hard tin-containing copper alloy wires (TH-SNCC-3) with a wire diameter of 0.08 mm are wound in a spiral shape with a pitch of about 0.7 mm around the heater core 3. The conductor wires 5a are wound on the heater core 3, and a tetrafluoroethylene-hexafluoropropylene copolymer (FEP) is extruded and coated with a thickness of about 0.15 mm as an insulating layer 7 to form the heating wire 1. In addition, the outer circumference of the heating wire 1 is further extruded and coated with a polyester resin containing a flame retardant as a heat-sealing portion 9 with a thickness of 0.2 mm. The cord-shaped heater 10 has this structure, and its finished outer diameter is 1.1 mm. Also, when considering flexibility and tensile strength, the heater core 3 is effective, but it is also possible to use multiple heating element wires drawn together or twisted together instead of the heater core 3. Also, if the cord-shaped heater 10 has flame retardancy that passes the UL1581 horizontal flame test: 2008, 4th edition by itself, it is preferable because it can improve the flame retardancy of the heater unit.

Next, the structure of the substrate 11 to which the cord-shaped heater 10 having the above-mentioned structure is bonded and fixed will be described. In the substrate 11 in this embodiment, as shown in FIG. 2, fiber threads 11a made of polyester multifilament having an apparent diameter of 0.5 mm are plain woven with a lattice interval of 10 mm, an opening 11c size of 9.5 mm, and a shielding rate of 12.9%, and are sandwiched between a pair of nonwoven fabrics 11b (basis weight 27 g/m ² , apparent thickness 1 mm) made of flame-retardant polyester fiber and attached with an adhesive. That is, the fiber threads 11a are composed of a first fiber thread group 11x arranged linearly in the left-right direction in FIG. 2 and a second fiber thread group 11y arranged linearly in the front-rear direction in FIG. 2. Note that this nonwoven fabric is obtained by laminating the material constituting the fiber while melt-extruding and spinning it to form a web, and is composed of filaments (long fibers). The fiber threads 11a are sandwiched between such a pair of nonwoven fabrics 11b, and these are fixed with an adhesive. The intersections of the fiber threads 11a are also fixed with an adhesive. The base material 11 having such a configuration has an overall basis weight of 100 g/ ^m2 .

Next, the configuration for arranging the cord-shaped heater 10 on the substrate 11 in a meandering shape and bonding and fixing it thereto will be described. In this embodiment, the meandering interval is 20 mm. FIG. 4 is a diagram showing the configuration of a hot press heater manufacturing device 13 for bonding and fixing the cord-shaped heater 10 on the substrate 11. First, there is a hot press jig 15, on which a plurality of locking mechanisms 17 are provided. As shown in FIG. 5, the locking mechanism 17 has a pin 19, which is inserted from below into a hole 21 drilled in the hot press jig 15. A locking member 23 is attached to the top of the pin 19 so as to be movable in the axial direction, and is constantly biased upward by a coil spring 25. Then, as shown by the imaginary line in FIG. 5, the cord-shaped heater 10 is hooked on the locking members 23 of the plurality of locking mechanisms 17 and arranged in a meandering shape.

Returning to FIG. 4, a press hot plate 27 is arranged above the multiple locking mechanisms 17 so that it can be raised and lowered. That is, the cord-shaped heater 10 is arranged in a serpentine shape while being hooked onto the locking members 23 of the multiple locking mechanisms 17, and the substrate 11 is placed on top of it. In this state, the press hot plate 27 is lowered to apply heat and pressure to the cord-shaped heater 10 and substrate 11, for example, at 230°C for 5 seconds. This causes the heat-sealing portion 9 on the cord-shaped heater 10 side and the heat-sealing fiber on the substrate 11 side to fuse together, and as a result, the cord-shaped heater 10 and substrate 11 are bonded and fixed together. When the press hot plate 27 is lowered to apply heat and pressure, the locking members 23 of the multiple locking mechanisms 17 move downward against the biasing force of the coil spring 25.

The meandering shape of the cord-like heater 10 is formed by combining straight portions 10a and curved portions 10b as shown in FIG. 6. In this case, as in this embodiment, it is preferable that the straight portions 10a of the cord-like heater 10 are arranged so as to be at an angle different from that of the first fiber thread group 11x and the second fiber thread group 11y. The mechanical strength of the substrate 11 is strong in the direction in which the fiber threads 11a are arranged, but the substrate becomes more likely to deform as the angle changes when pulled at an angle different from that of the fiber threads 11a. In particular, when the first fiber thread group 11x and the second fiber thread group 11y are arranged perpendicularly as in this embodiment, the substrate becomes most likely to deform when pulled at an angle shifted 45 degrees from the first fiber thread group 11x. By making the straight portions 10a of the cord-like heater 10 at an angle different from that of the first fiber thread group 11x and the second fiber thread group 11y, the substrate becomes less likely to deform when pulled at various angles. In FIG. 6, the nonwoven fabric 11b of the base material 11 is shown in a see-through manner.

An adhesive layer may be formed on the side of the base material 11 on which the cord-shaped heater 10 is not disposed, or double-sided tape may be applied. This is for fixing the heater unit 31 to the seat when attaching it to the seat.

By carrying out the above steps, a heater unit 31 for a vehicle seat heater as shown in FIG. 1 can be obtained. A cord is connected to both ends of the cord-shaped heater 10 in the heater unit 31 and to the temperature control device 39, and this cord connects the cord-shaped heater 10, the temperature control device 39, and the connector 35. The connector 35 is then used to connect to the vehicle's electrical system (not shown).

The heater unit 31 having the above configuration is embedded and disposed in a vehicle seat 41 in the state shown in FIG. 8. That is, as described above, the heater unit 31 is attached to the seat cover 43 or the seat pad 45 of the vehicle seat 41.

In the heater unit obtained in the above embodiment, the heat-sealed portion 9 of the cord-shaped heater 10 penetrates into the nonwoven fabric 11b of the substrate 11 and surrounds the fibers that make up the nonwoven fabric 11b, thereby firmly adhering the cord-shaped heater 10 to the substrate 11. In particular, if the substrate 11 contains heat-sealed fibers that have a core-sheath structure and the sheath portion has a low melting point, the sheath portion and the heat-sealed portion 9 of the cord-shaped heater will be fused to each other and integrated while surrounding the core portion. This will result in an even stronger adhesion between the cord-shaped heater 10 and the substrate 11.

As shown in the enlarged cross-sectional view of FIG. 7, the heat-sealed portion 9 of the cord-shaped heater 10 penetrates beyond the nonwoven fabric 11b of the substrate 11 until it directly contacts the fiber thread 11a, and the heat-sealed portion 9 and the fiber thread 11a are preferably fixed by heat fusion. When the breathability of the substrate 11 is improved, the density (basis weight) of the nonwoven fabric 11b of the substrate 11 is reduced, so that the cord-shaped heater 10 is likely to peel off due to the fiber coming off of the nonwoven fabric 11b. By directly fixing the heat-sealed portion 9 and the fiber thread 11a, such peeling can be prevented. In addition, the cord-shaped heater 10 and the fiber thread 11a are firmly integrated, which has the effect of making the heater unit less likely to deform. FIGS. 14 and 15 show enlarged photographs of the main parts of the heater unit. FIG. 14 is a photograph of the heater unit taken from the opposite side of the substrate to the side on which the cord-shaped heater is fixed. Figure 15 is a photograph of the cross section of a heater unit cut along the direction of the cord-shaped heater. In both Figures 14 and 15, it can be seen that the heat-sealed portion of the cord-shaped heater surrounds the fiber thread, and that the heat-sealed portion and the fiber thread are fixed together by heat fusion.

The present invention is not limited to the above embodiment. The cord heater 10 can be any of various cord heaters known in the art. The heating wire 1 can be configured as follows: as in the above embodiment, multiple conductor wires 5a are twisted or aligned, wound around the core wire 3, and an insulating layer 7 is applied to the outer periphery (see FIG. 3); multiple conductor wires 5a covered with an insulating coating 5b are twisted together (see FIG. 9); multiple conductor wires 5a covered with an insulating coating 5b are aligned together (see FIG. 10); multiple conductor wires 5a covered with an insulating coating 5b are twisted or aligned together and wound around the core wire 3 (see FIG. 11); and a heat fusion portion 9 is intermittently formed (see FIG. 12). A temperature detection wire, a short circuit detection wire, etc. may also be wound together. Specific examples of such other aspects are shown below. First, as shown in Figure 11, seven conductor strands 5a made of tin-copper alloy wires with a strand diameter of 0.08 mm are wound helically around the heater core 3 made of aromatic polyamide fiber bundles with an outer diameter of about 0.2 mm at a pitch of 1 mm to form the heating wire 1. The conductor strands 5a are covered with an insulating coating 5b made of polyurethane with a thickness of about 0.005 mm. The outer circumference of this heating wire 1 is extruded and covered with polyethylene resin mixed with a flame retardant to a thickness of 0.25 mm as the heat fusion part 9. The cord-shaped heater 10 is constructed in this way, and its finished outer diameter is 0.9 mm.

Examples of the core wire 3 include inorganic fibers such as glass fibers, polyester fibers such as polyethylene terephthalate, aliphatic polyamide fibers, aromatic polyamide fibers, fully aromatic polyester fibers, and other organic fibers such as monofilaments, multifilaments, spun yarns, or fibers having a configuration in which the organic polymer material constituting the fiber material is used as a core material and is covered with a thermoplastic organic polymer material. In addition, if the core wire 3 is made to have heat shrinkability and heat meltability, when the conductor wire 5a is broken, the core wire melts and cuts and shrinks due to abnormal heating, and the wound conductor wire 5a also follows the movement of the core wire 3, separating the ends of the broken conductor wire 5a. Therefore, the ends of the broken conductor wire do not come into contact with each other or come into contact with a small contact area such as a point contact, and abnormal heat generation can be prevented. In addition, if the conductor wire 5a is insulated by the insulating coating 5b, the insulating material of the core wire 3 does not need to be particular. For example, a stainless steel wire or a titanium alloy wire can be used. However, in case the conductor wire 5a breaks, it is better for the core wire 3 to be made of an insulating material.

As the conductor wire 5a, conventionally known wires can be used, such as copper wire, copper alloy wire, nickel wire, iron wire, aluminum wire, nickel-chromium alloy wire, copper-nickel alloy, iron-chromium alloy, and silver-containing copper alloy wire in which copper solid solution and copper-silver eutectic are in a fiber shape. Various cross-sectional shapes can also be used, and are not limited to those with a normally used circular cross section, and so-called rectangular wires may also be used. However, when winding the conductor wire 5a around the core wire 3, it is preferable to use wires that have a small amount of spring back when the heating wire 1 is wound around them. For example, a silver-containing copper alloy wire in which copper solid solution and copper-silver eutectic are in a fiber shape has excellent tensile strength and excellent tensile strength and bending strength, but is prone to spring back when the heating wire is wound around it. Therefore, when winding it around the core wire 3, the conductor wire 5a is likely to float or break due to excessive winding tension, and it is also not preferable because it is likely to develop a twisting tendency after processing. In particular, if the conductor wire 5a is covered with an insulating coating 5b, the restoring force of the insulating coating 5b will also be added. Therefore, it is important to select a conductor wire 5a with a small restoring rate to compensate for the restoring force of the insulating coating 5b.

The insulating coating 5b that covers the conductor wire 5a can be a conventionally known resin material, such as polyurethane resin, polyamide resin, polyimide resin, polyamideimide resin, polyesterimide resin, nylon resin, polyesternylon resin, polyethylene resin, polyester resin, vinyl chloride resin, fluororesin, and silicone resin. Multiple layers of these materials may be formed. Among these, if a material with heat fusion properties is used, the conductor wires 5a can be fused together, so that the heating wire 1 does not come apart during terminal processing such as connection to the connection terminal, and workability can be improved, which is preferable. In addition, when soldering is used as terminal processing, if the insulating coating 5b is removed by the heat during soldering, workability is greatly improved, so it is preferable that the material for the insulating coating 5b has good thermal decomposition properties.

When the conductor wires 5a are wound around the core material 3 by drawing or twisting them together, it is preferable to draw them together rather than twisting them together. This is because the diameter of the heating core 4 becomes smaller and the surface becomes smoother. In addition to drawing or twisting them together, it is also possible to braid the conductor wires 5a around the core material 3.

The insulating layer 7 may be formed by extrusion molding or the like, or may be covered with an insulating layer 7 previously formed into a tube shape; there is no particular limitation on the method of formation. The material constituting the insulating layer 7 may be appropriately designed depending on the usage form and usage environment of the cord-shaped heater, and may include various materials such as polyethylene resin, polyester resin, polyurethane resin, polyamide resin, vinyl chloride resin, fluorine resin, synthetic rubber, fluorine rubber, ethylene thermoplastic elastomer, and urethane thermoplastic elastomer. A protective coating may also be formed on the outer periphery of this insulating layer 7.

When forming the heat-sealed portion 9 on the outer circumference of the heating wire 1, the heat-sealed portion may be formed in a straight line or spiral line along the length of the cord-shaped heater, in a dot pattern, or intermittently as shown in FIG. 12, in addition to being formed around the entire circumference of the heating wire. In this case, if the heat-sealed portion is not continuous in the length direction of the cord-shaped heater, it is preferable because even if a part of the heat-sealed portion ignites, the burning portion will not spread. In addition, if the volume of the heat-sealed portion is sufficiently small, even if the heat-sealed portion is made of a flammable material, the burning material will disappear immediately and the fire will be extinguished, and drips (burning drips) will not occur. Therefore, it is preferable that the volume of the heat-sealed portion be the minimum that can maintain adhesion to the substrate. However, in such cases, it is preferable that the insulating layer 7 or the insulating coating 5b is made of a flame-retardant material.

As the material constituting the heat-sealed portion 9, a polymer composition having flame retardancy is preferably used. The polymer composition having flame retardancy here refers to one having an oxygen index of 21 or more in the flammability test of JIS-K7201 (1999). One having an oxygen index of 26 or more is particularly preferable. Specific examples of the material include thermoplastic polymer materials such as olefin resins, polyester resins, polyamide resins, vinyl chloride resins, polyurethane resins, modified noryl resins (polyphenylene oxide resins), aliphatic polyamide resins, polystyrene resins, polyolefin thermoplastic elastomers, polyester thermoplastic elastomers, polyurethane thermoplastic elastomers, and polyamide thermoplastic elastomers, and materials in which a flame retardant is appropriately blended into these thermoplastic polymer materials. Examples of the olefin resin include high-density polyethylene, low-density polyethylene, very low-density polyethylene, linear low-density polyethylene, polypropylene, polybutene, ethylene-α-olefin copolymers, and ethylene-unsaturated ester copolymers. Examples of ethylene-unsaturated ester copolymers include ethylene-vinyl acetate copolymers, ethylene-methyl (meth)acrylate copolymers, ethylene-ethyl (meth)acrylate copolymers, and ethylene-butyl (meth)acrylate copolymers, and these may be used alone or in a mixture of two or more. Here, "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid. Polyester-based thermoplastic elastomers include polyester-polyester type and polyester-polyether type, with the polyester-polyether type being preferred because of its high adhesiveness. Aliphatic polyamide resins are called nylons, and include n-nylons synthesized by polycondensation reaction of ω-amino acids and n,m-nylons synthesized by co-condensation polymerization reaction of diamines and dicarboxylic acids. Examples of n-nylons include nylon 6, nylon 11, and nylon 12, and examples of n,m-nylons include nylon 66, nylon 610, nylon 6I, nylon 6T, nylon 9T, and nylon M5T. Polyamide-based thermoplastic elastomers are known as block copolymers with polyamide as hard segments and polyether as soft segments. As the polyamide used as the hard segment, various kinds of polyamides are conceivable, such as the above-mentioned aliphatic polyamides, as well as aromatic polyamides such as para-aramids and meta-aramids. As the polyether used as the soft segment, various kinds of polyalkylene ether glycols such as polyethylene glycol, poly(1,2- and 1,3-)propylene ether glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol, block or random copolymers of ethylene oxide and propylene oxide, block or random copolymers of ethylene oxide and tetrahydrofuran, and those containing dihydric phenols such as bisphenol A and hydroquinone are conceivable. Among these, polyamide-based thermoplastic elastomers are preferred, which are particularly excellent in adhesiveness at high temperatures and have good compatibility in terms of melting point and adhesiveness when a nonwoven fabric of polyester fibers is used as a substrate, and block copolymers of aliphatic polyamides and polyalkylene ether glycols are more preferred, and block copolymers of nylon 11 or nylon 12 and polytetramethylene ether glycol are particularly preferred. Any of these may be selected, but it is preferable that the material melts at a temperature below the decomposition start temperature or below the melting point of the material constituting the insulating coating 5b or the insulating coating 7. In addition, polyester-based thermoplastic elastomers are examples of materials that have excellent adhesion to the substrate. Furthermore, in order to facilitate adhesion to the substrate and ensure adhesion strength after adhesion, it is preferable that the material constituting the heat-sealed portion 9 has a melt flow rate of 5.0 cm ³ /10 minutes or more. This melt flow rate is measured at a temperature of 200°C and a load of 2.16 kg according to the A method described in JIS-K7210:1999. Examples of flame retardants include metal hydrates such as magnesium hydroxide and aluminum hydroxide, antimony oxide, melamine compounds, phosphorus compounds, chlorine-based flame retardants, and bromine-based flame retardants. These flame retardants may be appropriately surface-treated by a known method. In particular, it is preferable that the surface treatment is such that the viscosity of the polymer composition constituting the heat-sealed portion 9 is reduced when melted. There is no particular limitation on the method for forming the adhesive layer 9, and it may be formed by known extrusion molding or coating, for example. In the present invention, the adhesive strength between the cord-shaped heater and the substrate is very important. If the adhesive strength is insufficient, the substrate and the cord-shaped heater may peel off during use, which may result in unexpected bending of the cord-shaped heater and the possibility of breakage of the conductor wire.

When using a cord-shaped heater as shown in FIG. 3, a good electrical conductor such as metal foil can be wrapped around the outer circumference of the conductor wire 5a in a portion of the length direction. When using a cord-shaped heater as shown in FIG. 3, a good electrical conductor such as metal foil can be wrapped around the outer circumference of the core material 3 (the inner surface of the conductor wire 5a) in a portion of the length direction. By doing so, in the portion where the good electrical conductor is wrapped, electricity is conducted to the good electrical conductor and is hardly conducted to the conductor wire 5a, so this portion does not generate heat. Therefore, it is possible to wind a good electrical conductor as described above in a portion where heat generation is not required. Also, if a good electrical conductor is wrapped around the end of the cord-shaped heater as described above, that portion becomes a lead wire portion. Therefore, the heating portion and the lead wire portion are formed continuously, and waterproofing is achieved without special connection processing or waterproofing processing. Therefore, such a configuration is preferably used in applications where waterproofing is required, such as humid environments, environments where water is splashed, and environments where ice is melted.

In addition, the cord-shaped heater 10 may be arranged in two or more pieces, not just one piece. In that case, one cord-shaped heater and the other cord-shaped heater may be arranged on the same surface of the substrate, or on different surfaces of the substrate. In addition, a cord-shaped sensor may be arranged in addition to the cord-shaped heater. A cord-shaped sensor may be a cord-shaped heater as described above in which the heating element is replaced with a detection element. For example, this cord-shaped sensor may be a temperature sensor that measures the change in resistance value of the detection element due to temperature, a temperature sensor that detects the melting of an insulating material that melts at a predetermined temperature and thereby conducts electricity to the detection element, a grip sensor or seat sensor that measures the change in capacitance of the detection element, or a pressure sensor or load sensor that detects or measures the tension or displacement of the detection element. This cord-shaped sensor may also be arranged on the same surface of the substrate as the cord-shaped heater, or on different surfaces of the substrate.

The substrate 11 is a combination of fiber yarns 11a and nonwoven fabric 11b arranged in a substantially planar shape. As the fiber yarns 11a, various forms such as multifilament, monofilament, spun yarn, etc. can be used. Among these, multifilament is preferable because of its excellent flexibility and strength. The apparent diameter of the fiber yarn may be appropriately set depending on the usage environment of the heater unit 31, etc., but is preferably 0.25 to 1 mm from the viewpoint of the balance between flexibility, mechanical strength, and breathability. The apparent diameter of the fiber yarn is a value obtained by actual measurement including the gaps between the fibers constituting the fiber yarn, and can be approximately calculated by the following formula.
D=0.0357×{T/(ρ×φ)} ^0.5
D: Apparent diameter of fiber yarn (mm)
T: fiber thread thickness (tex)
ρ: density of the fibers constituting the fiber yarn (g/cm ³ )
φ: Filling ratio of fiber yarn (ratio of apparent density of fiber yarn to density of fiber)

Materials constituting the fiber thread 11a include, for example, inorganic fibers such as glass fiber, alumina fiber, silica fiber, alumina-silica fiber, and carbon fiber; polyester fibers such as polyethylene terephthalate fiber, polyethylene naphthalate fiber, and polybutylene terephthalate fiber; synthetic fibers such as polyvinyl alcohol fiber, polyvinyl chloride fiber, polyvinylidene chloride fiber, polyethylene fiber, polypropylene fiber, polyacrylonitrile fiber, polystyrene fiber, polyurethane fiber, polyphenylene sulfide fiber, aramid fiber, nylon fiber, polyethersulfone fiber, polyetherketone fiber, and tetrafluoroethylene fiber; and natural fibers such as cotton, hemp, flax, silk, and wool. In addition, fibers with a core-sheath structure in which a sheath of a low-melting point material is formed around a core of a high-melting point material may be used. These may be selected appropriately taking into consideration the conditions of use, etc. Of course, the fiber thread 11a may be made of a single type of fiber, or may be made by combining multiple types of fibers.

Examples of the form in which the fiber threads 11a are arranged in a substantially planar shape include a meandering shape in which the fiber threads 11a are arranged in a zigzag shape, a plurality of fiber threads 11a are arranged at a predetermined interval, a plurality of fiber threads 11a are arranged at a predetermined interval and overlapped in layers so that the directions of the arrangement are different, a weaving of the fiber threads 11a (for example, a plain weave, a twill weave, a satin weave, etc.), a knitting of the fiber threads 11a (plain knitting, rib knitting, pearl knitting, double-sided knitting, pique knitting, jacquard knitting, raschel knitting, tricot knitting, etc.), etc. In particular, if the fiber threads 11a are woven to have openings 11c larger than the apparent diameter, or if the fiber threads 11a are knitted to have openings 11c larger than the apparent diameter, sufficient breathability can be obtained by the openings 11c. Furthermore, the weaving or knitting structure can prevent the fiber threads 11a from shifting even when an external force is applied. The size of the opening 11c is preferably, for example, about 10 to 30 times the apparent diameter of the fiber thread 11a. The size of the opening 11c is determined at the portion of the opening 11c that has the maximum diameter. For example, if the opening 11c is rectangular, the length of the diagonal is the size of the opening 11c. From another perspective, the shielding rate of the fiber thread 11a is preferably 8.8 to 23.2%. The shielding rate is the ratio of the area occupied by the fiber thread 11a to a unit area. When the apparent diameter of the fiber thread 11a is constant, the larger the size of the opening 11c, the smaller the shielding rate. When the size of the opening 11c is constant, the larger the apparent diameter of the fiber thread 11a, the larger the shielding rate.

In the above embodiment, the angle between the first fiber thread group 11x and the second fiber thread group 11y is 90 degrees, but of course it may be a different angle. However, if this angle is too small, the mechanical strength in a certain direction may be insufficient, so it is preferable to set the angle to 45 degrees or more. In addition to the first fiber thread group 11x and the second fiber thread group 11y, a third fiber thread group, a fourth fiber thread group, etc., which have different angles, may be used. For example, as shown in FIG. 13, a substrate 11 in which the first fiber thread group 11x, the second fiber thread group 11y, and the third fiber thread group 11z are arranged at angles different by 60 degrees each may be considered. In the case of the embodiment shown in FIG. 13, the straight portion 10a of the cord-shaped heater 10 may be arranged so that the first fiber thread group 11x, the second fiber thread group 11y, and the third fiber thread group 11z are all at different angles, but the effect of the present invention can be sufficiently obtained if the straight portion 10a is arranged so that the first fiber thread group 11x, the second fiber thread group 11y, and the third fiber thread group 11z are at different angles.

The nonwoven fabric 11b may be formed by various methods such as a wet method, a thermal bond method, a chemical bond method, a needle punch method, a spunlace method, etc. As the fibers constituting the nonwoven fabric 11b, various types of fibers can be used, such as inorganic fibers such as glass fibers, alumina fibers, silica fibers, alumina-silica fibers, and carbon fibers, polyester fibers such as polyethylene terephthalate fibers, polyethylene naphthalate fibers, and polybutylene terephthalate fibers, synthetic fibers such as polyvinyl alcohol fibers, polyvinyl chloride fibers, polyvinylidene chloride fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, polystyrene fibers, polyurethane fibers, polyphenylene sulfide fibers, aramid fibers, nylon fibers, polyethersulfone fibers, polyetherketone fibers, and tetrafluoroethylene fibers, and natural fibers such as cotton, hemp, flax, silk, and wool. Also, a heat-fusible fiber having a core-sheath structure in which a sheath of a low-melting point material is formed around a core of a high-melting point material may be used. If such a heat-fusible fiber is used, when the heat-fusible portion 9 is formed on the outermost layer of the cord-like heater 10, the sheath of the heat-fusible fiber and the heat-fusible portion 9 are fused to each other and integrated while surrounding the core of the heat-fusible fiber, so that the adhesion between the cord-like heater 10 and the substrate 11 is very strong. These fibers may be appropriately selected in consideration of the conditions of use, etc. Of course, the nonwoven fabric 11b may be made of a single type of fiber, or may be a hybrid nonwoven fabric 11b made by combining multiple types of fibers. In addition, the fibers constituting the nonwoven fabric 11b may be filaments (long fibers) having no fiber length, or staples (short fibers) having a predetermined fiber length. Filaments are preferred because they have a high strength as the nonwoven fabric 11b and also ensure the fixation of the cord-like heater 10. In addition, the substrate 11 is preferably one having flame retardancy that passes the combustion test of FMVSS No. 302 for automobile inner layer materials. Here, FMVSS stands for Federal Motor Vehicle Safety Standard, and No. 302 of FMVSS specifies the combustion test for automotive interior materials. For this reason, it is preferable to use flame-retardant fibers that pass a flame retardant test (for example, JIS-L1091:1999) as the fibers constituting the fiber thread 11a and the nonwoven fabric 11b. By using such flame-retardant fibers, the substrate is endowed with excellent flame retardancy. The thickness of the nonwoven fabric 11b (measured when dry) is preferably, for example, about 0.6 mm to 1.4 mm. If the nonwoven fabric 11b of such a thickness is used, when the cord-shaped heater 10 and the substrate 11 are bonded and fixed by heating and pressing, the nonwoven fabric 11b will be well bonded to 30% or more, preferably 50% or more of the outer periphery of the cord-shaped heater, and thus a strong bond state can be obtained. The basis weight (weight per unit area) of the nonwoven fabric 11b is preferably about 80 to 120 g/ ^m2 for the entire substrate 11. Nonwoven fabric 11b with such a basis weight has excellent breathability and sufficient mechanical strength.

In addition, when heat-sealing fibers are used in the nonwoven fabric 11b, the mixing ratio of the heat-sealing fibers is preferably 5% or more, and more preferably 20% or less. If the mixing ratio of the heat-sealing fibers is less than 5%, sufficient adhesion is difficult to obtain. If the mixing ratio of the heat-sealing fibers exceeds 20%, the nonwoven fabric becomes hard, and not only may the seated person complain of discomfort, but also the adhesion to the cord-shaped heater may decrease. The mixing ratio of the flame-retardant fibers is 70% or more, and preferably 70% or more and 95% or less. If the mixing ratio of the flame-retardant fibers is less than 70%, sufficient flame retardancy may not be obtained. If the mixing ratio of the flame-retardant fibers exceeds 95%, the mixing ratio of the heat-sealing fibers is relatively insufficient, and sufficient adhesion is difficult to obtain. It is not necessary for the mixing ratio of the heat-sealing fibers and the mixing ratio of the flame-retardant fibers to be 100% in total, and other fibers may be mixed as appropriate.

It is also possible to color the fibers that make up the nonwoven fabric 11b. For example, in the case of a vehicle seat 41 in which synthetic leather or natural leather is used as the material for the seat upholstery 43, these materials are not breathable, so multiple through holes are formed in the seat upholstery 43 to provide breathability. When the heater unit 31 is placed in such a vehicle seat 41, the heater unit 31 is visible through the through holes. For this reason, it is preferable to color the fibers that make up the nonwoven fabric 11b black or a similar color to the seat upholstery so that they are as inconspicuous as possible. Of course, it is also possible to color the fiber threads 11a and the cord-shaped heater 10 black or a similar color to the seat upholstery.

Regarding the form in which the fiber thread 11a and the nonwoven fabric 11b are combined, for example, the fiber thread 11a arranged in a plane is attached to one side of the nonwoven fabric 11b, or the fiber thread 11a arranged in a plane is sandwiched between a pair of nonwoven fabrics 11b. In this case, the fiber thread 11a and the nonwoven fabric 11b may be attached, for example, by an adhesive. In addition, when a pair of nonwoven fabrics 11b is used, the nonwoven fabrics 11b may be attached to each other, for example, by an adhesive. Various adhesives are known, and an appropriate adhesive may be selected in consideration of compatibility with the fiber thread 11a and the nonwoven fabric 11b. However, in light of recent environmental circumstances, it is preferable to select an adhesive that takes VOCs into consideration. In addition, if a thermoplastic resin is used as the fiber material of the fiber thread 11a and/or the nonwoven fabric 11b, the fiber thread 11a and the nonwoven fabric 11b can be attached to each other by heating and pressing the fiber thread 11a and the nonwoven fabric 11b under appropriate conditions in a stacked state. Specific examples of the method include a method using a press hot plate as described above, or a method of passing the nonwoven fabric 11b between heated rolls.

In addition, when a pair of nonwoven fabrics 11b are used, they may be made of different materials. For example, the following is possible. It is possible to select one of the nonwoven fabrics 11b with a high porosity, i.e., a small amount of fiber per unit volume. By making the nonwoven fabric 11b on the side where the cord-shaped heater 10 will be present on the heater unit surface with a high porosity, the cord-shaped heater 10 can more reliably penetrate into the nonwoven fabric 11b, resulting in a flat heater unit 31. It is also possible to make one of the nonwoven fabrics 11b with a high porosity and melt-fill the nonwoven fabric 11b with other resins to create a composite material. In addition, by combining various nonwoven fabrics, such as nonwoven fabrics with excellent flame retardancy, nonwoven fabrics with high tensile strength, nonwoven fabrics with excellent chemical resistance, nonwoven fabrics with excellent heat resistance, nonwoven fabrics with excellent voltage resistance characteristics, nonwoven fabrics with electromagnetic wave shielding properties, nonwoven fabrics with low resilience, nonwoven fabrics with excellent low-temperature brittleness, and nonwoven fabrics with high (or low) thermal conductivity, it is possible to create a heater unit 31 with additional functions.

As for the adhesive layer for fixing the heater unit 31 to the seat, in terms of the elasticity of the base material 11 and maintaining a good texture, it is preferable to form an adhesive layer consisting of only an adhesive on a release sheet or the like, and then transfer the adhesive layer from the release sheet to the surface of the base material 11 to form the adhesive layer. This adhesive layer is preferably flame-retardant, and preferably has flame retardancy that allows it to pass the combustion test for automobile interior materials, FMVSS No. 302, by itself. For example, a polymeric acrylic adhesive may be used.

When the cord-like heater 10 is disposed on the substrate 11, the cord-like heater 10 may be fixed to the substrate 11 in other manners than by bonding and fixing by fusion through heating and pressure. For example, the cord-like heater 10 may be fixed to the substrate 11 by sewing, or by sandwiching and fixing the cord-like heater 10 between a pair of substrates 11 with adhesive, or other manners may be used. When fixing the cord-like heater 10 to the substrate 11, it is preferable that the cord-like heater 10 is fixed in direct contact with the fiber thread 11a of the substrate 11. When fixing the cord-like heater 10 to the substrate 11 by sewing, for example, a substrate 11 with fiber thread 11a disposed on the surface or a substrate 11 with a sufficiently small density (basis weight) of the nonwoven fabric 11b may be used so that the cord-like heater 10 and the fiber thread 11a are sufficiently close to each other, and then they may be tightened and brought into contact by sewing.

The arrangement of the serpentine shape of the cord-shaped heater 10 may be designed to a predetermined shape by appropriately combining the straight portions 10a and the curved portions 10b according to the object to be heated and the installation location. The straight portions 10a are preferably arranged so as to be at a different angle from the first fiber thread group 11x and the second fiber thread group 11y, but this does not have to be the case for all of the straight portions 10a. A portion of the straight portions 10a may be parallel to the first fiber thread group 11x or the second fiber thread group 11y. The effect of the present invention can be fully obtained as long as 50% or more of the straight portions 10a of the arranged cord-shaped heater 10 are arranged so as to be at a different angle from the first fiber thread group 11x and the second fiber thread group 11y.

As described above in detail, the present invention provides a heater unit with excellent breathability and mechanical strength. This heater unit can be suitably used as a heating means that requires breathability, such as electric blankets, electric carpets, car seat heaters, steering wheel heaters, heated toilet seats, heaters for anti-fog mirrors, cooking appliances, and heaters for floor heating.

REFERENCE SIGNS LIST 10 cord-shaped heater 10a straight portion 10b curved portion 11 substrate 11a fiber yarn 11b nonwoven fabric 11c opening 11x first fiber yarn group 11y second fiber yarn group 31 heater unit 41 vehicle seat

Claims (3)

A heater unit having a base material and a cord-shaped heater, the cord-shaped heater being disposed and fixed on the base material,
The substrate is a combination of fiber yarns and nonwoven fabric arranged in a substantially planar shape,
the cord-like heater is fixed in direct contact with the fiber yarn ,
A heat-sealed portion is formed on the outermost layer of the cord-shaped heater,
The heat-sealed portion is fixed to the nonwoven fabric and the fiber yarn by heat fusion,
The fiber yarn is woven, knitted, or overlapped in different directions, and the heater unit has an opening larger than the apparent diameter of the fiber yarn . The heater unit according to claim 1, wherein the base material is made of a fiber thread and a pair of nonwoven fabrics, and the fiber thread is sandwiched between the pair of nonwoven fabrics. 3. A vehicle seat comprising a seat cover and a seat pad, the heater unit according to claim 1 being disposed between the seat cover and the seat pad.

Images