JP2000318503A - Occupant detecting sensor attaching structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor with durability, even in high-temperature and humidity environment or in a low-temperature environment and perform attaching work in a general work environment. SOLUTION: These occupant detecting sensors 30 are attached to a cushion pad 19 of a vehicle seat 10 by hot-melt adhesives having the low embrittlement temperature lower than -50 deg.C, having an upper limit and lower limit such that the Vicat softening point corresponds to the thermal deformation temperature of an insulating seat as the upper limit and the lower limit is 70 deg.C. Accordingly, adhesive force can be maintained even in a low-temperature environment in a cabin by using the hot-melt adhesives having characteristics, in which the low embrittlement temperature is lower than -50 deg.C. The adhesive force can also be maintained in a high-temperature and humidity environment in the cabin by using the hot-melt adhesives having an upper limit and lower limit such that the Vicat softening point corresponds to the thermal deformation temperature of an insulating seat as the upper limit and the lower limit is 70 deg.C. The occupant detecting sensors can be bonded without being thermally affected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in a mounting structure of an occupant detection sensor.

[0002]

2. Description of the Related Art As a mounting structure of an occupant detection sensor, for example, Japanese Unexamined Patent Publication No. Hei.
It has been known. According to FIG. 1 of the publication,
A piezoelectric element 1 formed by forming a polymer material such as polyvinylidene fluoride in a thin film shape and attaching a flexible electrode film to both surfaces of the polymer material (the reference numerals are the same as those described in the publication) ) Is attached to the seat 7. conventionally,
In order to attach the piezoelectric element 1 to the seat 7, a chloroprene rubber-based solvent-type adhesive was generally used.

[0003]

However, with a chloroprene rubber-based solvent-type adhesive, in a severe environment of high temperature and high humidity or low temperature in a vehicle cabin, at high temperature and high humidity, the adhesive strength may be reduced and the piezoelectric element 1 may be peeled off. At a low temperature, there is a possibility that the adhesion becomes brittle and easily cracked. Further, the piezoelectric element 1 is attached to the seat 7 with a chloroprene rubber-based solvent type adhesive.
When the chloroprene rubber-based solvent-based adhesive is used as a solvent, it is necessary to improve the working environment because the solvent is used, and the production equipment may be costly.

An object of the present invention is to provide a mounting structure for an occupant detection sensor that is durable even in a high-temperature, high-humidity or low-temperature environment and that can be operated in a general work environment.

[0005]

To achieve the above object, an occupant having a conductor coating formed on an insulating sheet, a terminal attached to the conductor coating, and a protective sheet placed over the terminal is provided. In a mounting structure of an occupant detection sensor in which a detection sensor is mounted on a cushion pad of a vehicle seat via an adhesive with a conductive film as a surface to be bonded, the adhesive has a low-temperature embrittlement temperature lower than −50 ° C., The hot-cut adhesive has a Vicat softening point temperature whose upper limit is the temperature corresponding to the heat deformation temperature of the insulating sheet, and whose lower limit is 70 ° C., which is between the upper and lower limits.

An occupant detection sensor in which a conductor film is formed on an insulating sheet, terminals are attached to the conductor film, and the terminals are covered with a protective sheet, is used as a cushion pad for a vehicle seat using the conductor film as a bonding surface. Is attached via a hot melt adhesive. The use of a hot-melt adhesive improves the workability of bonding. For example, when a chloroprene rubber-based solvent-type adhesive is used, a solvent is used. Therefore, it is necessary to prepare a work environment, and the work environment is selected.
However, the hot-melt adhesive does not require the use of a solvent, and can be operated in a general work environment.

Further, by using a hot-melt adhesive having a property that the low-temperature embrittlement temperature is lower than −50 ° C., the adhesive strength is maintained even in a low-temperature environment in a vehicle compartment. The upper limit is the temperature at which the Vicat softening point temperature corresponds to the thermal deformation temperature of the insulating sheet, the lower limit is 70 ° C., and the use of a hot-melt adhesive between the upper and lower limits allows high temperature in the vehicle interior. The bonding force is maintained even in an environment of high humidity, and the bonding is performed so as not to thermally affect the occupant detection sensor.

That is, considering use at low temperatures,
A low temperature embrittlement temperature of -50 ° C is required. This is because if the temperature is higher than this, there is a risk of embrittlement in cold regions. When considering use in a high-temperature atmosphere, the Vicat softening temperature must exceed 70 ° C. If the temperature is lower than this, there is a possibility that when the temperature is excessively increased due to burning or the like, the material is softened and the adhesive strength is significantly reduced. When considering the heat resistance of the bonding target (here, the occupant detection sensor), it is not possible to exceed the thermal deformation temperature (for example, 180 ° C.) of the insulating sheet to be bonded. This is because the insulating sheet is thermally deformed, and it is necessary to suppress the melting temperature of the adhesive below the above-mentioned thermal deformation temperature (180 ° C.). This is converted into a Vicat softening temperature of 125 ° C., which corresponds to, for example, the Vicat softening temperature when a general polyester resin film is used for an insulating sheet.

According to a second aspect, the insulating sheet has a heat deformation temperature of 1.
It is characterized by being a polyester resin film in the range of 85 ° C to 195 ° C. By using a polyester resin film having a heat deformation temperature in the range of 185 ° C. to 195 ° C. for the insulating sheet, an increase in the cost of the occupant detection sensor is suppressed.

According to a third aspect of the present invention, the adhesive is not interposed between the terminal and the cushion pad. By extending the protective sheet over the edge of the adhesive layer and interposing it between the cushion pad and the adhesive layer, the extension of the protective sheet served as an anti-bending stay for the insulating sheet. Characterized by the following.

By preventing the adhesive from being interposed between the terminal and the cushion pad, a part of the insulating sheet protrudes from the edge of the adhesive layer. Then, the protective sheet covering the terminal is extended, and is interposed between the cushion pad and the adhesive layer beyond the edge of the adhesive layer. That is, the extension of the protective sheet is inserted between the cushion pad and the adhesive layer to serve as a stay for preventing the insulating sheet from bending, thereby preventing the conductor coating of the occupant detection sensor from cracking.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view of a vehicle seat to which an occupant detection sensor according to a first embodiment of the present invention is mounted. The vehicle seat 10 has a seat back 12 attached to a seat cushion 11 so as to be reclined. The seat cushion 11 is obtained by attaching a cushion material 15 to a frame 14 and covering the cushion material 15 with a skin 16. The seat back 12 includes a frame 18
A cushion pad 19 is attached to the cushion pad 19, and the cushion
2 is covered. The seat back 12 includes a pillow 23. The cushion pad 19 is preferably made of urethane foam.

The occupant detection sensor unit 20 has a plurality of occupant detection sensors 30... (... CPU to determine information (central proc
An essor unit 24 is attached to the frame 18. 25 are wires for electrically connecting the plurality of detection sensors 30 to the CPU 24. That is, the vehicle seat 10 is, for example, a next-generation type capable of grasping the size and posture of an occupant when operating an airbag or the like and outputting information for activating the airbag so as to be most suitable for the occupant. Sheet.

FIG. 2 is a sectional view taken along line 2-2 of FIG.
2 shows a longitudinal section of the occupant detection sensor 30 of the embodiment. FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1 and shows a cross section of the occupant detection sensor 30 of the first embodiment. The mounting structure of the occupant detection sensor 30 is such that a conductor film 32 is formed on an insulating sheet 31, a terminal 33 shown in FIG. 3 is attached to the conductor film 32, and the terminal 33 is covered with a protection sheet 34. 30 is prepared, and the occupant detection sensor 30 is used as the cushion pad 19 of the vehicle seat 10 with the conductive film 32 as the surface to be bonded.
Is attached via an adhesive 35.

The insulating sheet 31 has a heat deformation temperature of 185 ° C.
Polyester resin films in the temperature range of from about to 195 ° C are preferred. The thermal deformation temperature of the insulating sheet 31 is 185 ° C
By using the polyester resin film in a temperature range of from about 195 ° C. to about 195 ° C., it is possible to suppress an increase in the cost of the occupant detection sensor 30. For example, if a film having a high thermal deformation temperature such as a polyimide resin film must be used, the cost of the occupant detection sensor 30 will increase.

The conductor film 32 is formed by coating the insulating sheet 31 with C
(Carbon) First conductive film 32a with paint ink
And a second conductor film 32b is formed on the first conductor film 32a with Ag (silver) paste ink. When a person (dielectric) approaches the conductor film 32, the The capacity changes. The occupant detection sensor unit 20 shown in FIG.
4 (see FIG. 1).

The adhesive 35 is interposed between the conductor coating 32 and the cushion pad 19, and must be durable and highly reliable even in an environment of high temperature, high humidity, or low temperature. As described later, the low-temperature embrittlement temperature is lower than −50 ° C., and the Vicat softening point temperature is the heat deformation temperature of the insulating sheet 31 (from 185 ° C. to 195 ° C.).
C)), and the lower limit is 70 ° C. or higher, and the hot melt adhesive is between the upper and lower limits.

The operation of the above-described structure for mounting the occupant detection sensor 30 will now be described. FIGS. 4A to 4D are explanatory views of the operation of the mounting structure of the occupant detection sensor according to the first embodiment of the present invention. In (a), the occupant detection sensor 30 and the cushion pad 19 of the vehicle seat 10 are prepared.
In (b), the conductor coating 32 of the occupant detection sensor 30
The adhesive 35 in a hardened state is placed on the side. In addition, this adhesive 35 is 30 μm to 2
It was extruded to 50 μm.

In (c), as described later, the adhesive 35 has an upper limit of a Vicat softening point temperature lower than a temperature corresponding to the heat deformation temperature (185 ° C. to 195 ° C.) of the insulating sheet 31 and is 70 ° C. or higher. Is the lower limit, and the hot melt adhesive is between the upper and lower limits. Therefore, the occupant detection sensor 30 and the adhesive 35 are changed from 120 ° C to 180 ° C.
Heat bonding at temperatures up to The insulating sheet 31
Since the polyester resin film has a heat deformation temperature in the range of 185 ° C. to 195 ° C., there is no fear that heat deformation occurs at a temperature in the range of 120 ° C. to 180 ° C. That is, the adhesive force can be maintained even in an environment of high temperature and high humidity in the vehicle cabin, and the occupant detection sensor 30 can be bonded without thermal influence. In addition, the low temperature embrittlement temperature is-
By using a hot-melt adhesive having a characteristic lower than 50 ° C., the adhesive strength can be maintained even in a low temperature environment in a vehicle compartment.

In (d), the occupant detection sensor 30 is pressed against the cushion pad 19 of the vehicle seat 10 as shown by an arrow, and the bonding is completed after the adhesive 35 has cooled. The adhesive 35 is a hot-melt adhesive, and the use of the hot-melt adhesive can improve the bonding workability. For example, when a chloroprene rubber-based solvent-type adhesive is used, a solvent is used. Therefore, it is necessary to prepare a work environment, and the work environment is selected. However, the hot-melt adhesive does not require the use of a solvent, and can be operated in a general work environment.

[0021]

An experimental example according to the present invention will be described below.

[0022]

[Table 1]

Table 1 shows the low-temperature embrittlement temperature of the adhesive. Here, the low-temperature embrittlement temperature is a measurement in accordance with JIS K7311, and is a temperature (° C.) at which the environmental temperature of the test piece of the adhesive is dropped every 5 ° C. and the test piece is broken with a predetermined hammer. . Here, a hot melt adhesive having a low temperature embrittlement temperature lower than −50 ° C. was usable. That is, considering use at a low temperature, the low-temperature embrittlement temperature is -5.
0 ° C. is required. This is because if the temperature is higher than this, there is a risk of embrittlement in cold regions. In addition, low temperature embrittlement temperature measurement is a limit at -70 degreeC.

Sample 1 is a polycarbonate-based urethane resin (a product equivalent to Rezamine P890 manufactured by Dainichi Seika Kogyo Co., Ltd.). Sample 2 is a polycarbonate urethane resin (a product equivalent to Rezamine P897 manufactured by Dainichi Seika Kogyo Co., Ltd.)
The low-temperature embrittlement temperature is -70 ° C or less, and the judgment is usable. Sample 3 is a polycarbonate urethane resin (equivalent to Rezamine P880 manufactured by Dainichi Seika Kogyo Co., Ltd.), and has a low-temperature embrittlement temperature of −70 ° C. or less, and the determination is usable.

Sample 4 is a polyester-based urethane resin (Nippon Matai UH203 or equivalent) having a low-temperature embrittlement temperature of -65 ° C., and the determination is usable. Sample 5
Is a polyester urethane resin (Nihon Matai UH604
(Equivalent product), the low-temperature embrittlement temperature is -45 ° C, and the judgment cannot be used. Sample 6 is a polyamide resin (Daicel Chemical Industries, Ltd., Daiamide equivalent), the low-temperature embrittlement temperature is −25 ° C., and the judgment cannot be used.
Sample 7 is made of polybutylene terephthalate (PBT)
Resin (Daicel Chemical Industries Thermolight 2810 or equivalent)
And the low-temperature embrittlement temperature is −25 ° C., and the judgment cannot be used. That is, it was determined that samples 1 to 4 could be used and samples 5 to 7 could not be used.

[0026]

[Table 2]

Table 2 shows the Vicat softening point temperature of the adhesive. Here, the Vicat softening point temperature is JIS K720.
6. The measurement according to 6, wherein the tip of a needle having a predetermined weight placed on the upper end is applied to a test piece of adhesive, the test piece is heated, and the temperature at which the tip of the needle reaches a predetermined depth (° C.) It is. When considering use in a high-temperature atmosphere, the Vicat softening temperature must exceed 70 ° C. If the temperature is lower than this, there is a possibility that when the temperature is excessively increased due to burning or the like, the material is softened and the adhesive strength is significantly reduced.

When considering the heat resistance of the occupant detection sensor 30 shown in FIGS. 2 and 3 to be bonded, the heat deformation temperature (for example, 180 ° C.) of the insulating sheet 31 to be bonded cannot be exceeded. This is because the insulating sheet 31 is thermally deformed.
C). When this is converted into a Vicat softening temperature, the Vicat softening temperature is 125 ° C. Therefore, when the Vicat softening temperature is 70 ° C. or more, the Vicat softening temperature 1
A hot melt adhesive having a temperature of less than 25 ° C. was usable. Samples 1 to 7 are the same as those shown in Table 1.

Sample 1 has a Vicat softening temperature of 136.
° C, and the insulating sheet 31 shown in FIGS. 2 and 3 may be thermally deformed. Since the sample 2 has a Vicat softening temperature of 140 ° C. and the insulating sheet 31 may be thermally deformed, the determination cannot be used. Since the sample 3 has a Vicat softening temperature of 95 ° C. and does not thermally deform the insulating sheet 31, the determination is usable.

Sample 4 has a Vicat softening temperature of 64 ° C.
Therefore, the insulating sheet 31 is not thermally deformed. However, when the use in a high-temperature atmosphere is considered, there is a possibility that the adhesive strength is remarkably reduced due to softening, so that the judgment cannot be used. Sample 5 has a Vicat softening temperature of 55 ° C. and does not thermally deform the insulating sheet 31. However, when the use in a high-temperature atmosphere is considered, there is a possibility that the adhesive strength is remarkably reduced due to softening, so that the judgment cannot be used. For samples 6 and 7, the determination cannot be used for the same reason as for sample 5. That is, it was determined that only sample 3 could be used and samples 1 to 7 could not be used.

From Tables 1 and 2, the low-temperature embrittlement temperature of the adhesive is lower than −50 ° C., and the Vicat softening point temperature is the temperature corresponding to the heat deformation temperature of the insulating sheet 31 (see FIGS. 2 and 3). The upper limit is set to 70 ° C. and the lower limit is set to 70 ° C. The hot melt adhesive between the upper and lower limits is the polycarbonate urethane resin of Sample 3 (Resamine manufactured by Dainichi Seika Kogyo Co., Ltd.).
P880 equivalent).

[0032]

[Table 3]

Table 3 shows the overall evaluation of the adhesive, and here, only the results are simply shown. Sample 1 to Sample 7
Is the same sample as that shown in Tables 1 and 2, and is the result of adding the examination result of the acrylic pressure-sensitive adhesive tape to Sample 8. The hot adhesive strength was determined by using a 25 mm-wide band-like adhesive sheet in urethane foam (the cushion pad 1 shown in FIG. 1).
9) and 200 mm /
min at one end towards the other end, i.e. 18
Bend at 0 ° and peel off. At this time, when the peeling force is 2N (Newton) or more and the urethane foam on the other side breaks, "O" indicates that the adhesive itself breaks when the peeling force is less than 2N or the interface between the adhesive and the urethane foam condenses. What is destroyed is indicated by "x". Samples 1 to 5 were "O", and samples 7 to 8 were "X".

In the hot creep, a band adhesive sheet having a width of 25 mm is adhered to urethane foam (the material of the cushion pad shown in FIG. 1), and a 50 g weight is hung on one end of the band adhesive sheet in an atmosphere of 80 ° C. , Leave for 24 hours,
If the downward displacement is less than 5 mm, the result is indicated by "O", and if the downward displacement is 5 mm or more, the result is represented by "X". Samples 1 to 3 were "O", and samples 4 to 8 were "X".

For low-temperature flex cracking (-40 ° C.), a band-shaped adhesive sheet was adhered to a sensor, and the laminate was subjected to φ2 at -40 ° C.
The wire is wrapped in a U-shape around an iron wire of mm, and is marked with "O" if the adhesive does not crack, and "X" if the adhesive is cracked.
It is what it was. Samples 1 to 4 were "O", and samples 5 to 8 were "X".

The sensor was deformed by bonding a band-shaped adhesive sheet to the sensor, leaving the laminate in an atmosphere of 50 ° C. and 95% humidity for 24 hours, and further standing at room temperature for 24 hours. If not, the result is indicated by "O", and if deformation is visually observed, the result is indicated by "X". Samples 3-5
Samples 7 and 8 were "O", and samples 1, 2, and 6 were "X". Here, Samples 1 and 2 were obtained by thermally deforming the insulating sheet because the Vicat softening temperature shown in Table 2 was higher than 125 ° C., and Sample 6 was obtained by absorbing moisture because the adhesive was a polyamide resin. It is. When bonding, it is necessary to return (flatten) the deformation and temporarily fix it.

That is, hot adhesive strength, hot creep,
From the measurement results of the low-temperature flex cracking (−40 ° C.) and the deformation of the sensor, it can be said that all “O” are the polycarbonate-based urethane resins of Sample 3.

FIG. 5 is a cross-sectional view of the occupant detection sensor according to the second embodiment of the present invention. The same parts as those of the occupant detection sensor 30 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. I do. 19 is a cushion pad, 31 is an insulating sheet, 32 is a conductor film, 33 is a terminal, 35 is an adhesive, and the occupant detection sensor 40 does not interpose the adhesive 35 between the terminal 33 and the cushion pad 19. By doing so, it is assumed that a part of the insulating sheet 31 protrudes from the edge 41 of the adhesive 35 layer. Then, the protection sheet 44 covering the terminals 33 is extended, and the protection sheet 44 is extended between the cushion pad 19 and the adhesive 35 layer beyond the edge 41 of the adhesive 35 layer.
The symbol a serves as a stay for preventing the insulating sheet 31 from bending.

That is, the extension 44a of the protection sheet 44
Is inserted between the cushion pad 19 and the adhesive 35 layer to serve as a stay for preventing the insulating sheet 31 from bending, so that the conductor coating 32 of the occupant detection sensor 40 can be prevented from cracking.

In the first embodiment, as shown in FIG. 4, an adhesive 35 extruded in a film form of 30 μm to 250 μm is placed on the occupant detection sensor 30 side, and the occupant detection sensor 30 is mounted on the cushion pad 19. Although the description has been given of the heat bonding, the present invention is not limited to this. The bonding may be performed by applying the adhesive 35 to the cushion pad 19 side.

[0041]

According to the present invention, the following effects are exhibited by the above configuration. According to a first aspect of the present invention, a conductor film is formed on an insulating sheet, a terminal is attached to the conductor film, and an occupant detection sensor having the terminal covered with a protective sheet is used as a vehicle seat with the conductor film adhered. The cushion pad was attached via a hot melt adhesive. At this time, since the hot-melt adhesive is used, the workability of the bonding can be improved. For example, when a chloroprene rubber-based solvent-type adhesive is used, a solvent is used. Therefore, it is necessary to prepare a work environment, and the work environment is selected. But,
The hot melt adhesive does not require the use of a solvent, so that it can be operated in a general work environment.

Further, by using a hot-melt adhesive having a characteristic that the low-temperature embrittlement temperature is lower than −50 ° C., the adhesive strength can be maintained even in a low-temperature environment in a vehicle compartment. The upper limit of the temperature corresponding to the thermal deformation temperature of the Vicat softening point is set to 70 ° C., and the hot melt adhesive between the upper and lower limits is used. The adhesive force can be maintained even in an environment of high humidity, and the occupant detection sensor can be adhered so as not to thermally affect the sensor.

According to a second aspect, the insulating sheet has a heat deformation temperature of 1
Since the polyester resin film in the range of 85 ° C. to 195 ° C. is used, a rise in the cost of the occupant detection sensor can be suppressed.

According to a third aspect of the present invention, a part of the insulating sheet protrudes from the edge of the adhesive layer by preventing the adhesive from intervening between the terminal and the cushion pad. By extending the protective sheet covering the terminals and interposing between the cushion pad and the adhesive layer beyond the edge of the adhesive layer, the role of the bending prevention stay of the insulating sheet at the extension of the protective sheet is obtained. Therefore, it is possible to prevent the conductor coating of the occupant detection sensor from cracking.

[Brief description of the drawings]

FIG. 1 is a perspective view of a vehicle seat equipped with an occupant detection sensor according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;

FIG. 4 is an operation explanatory view of the mounting structure of the occupant detection sensor according to the first embodiment of the present invention.

FIG. 5 is a transverse sectional view of an occupant detection sensor according to a second embodiment of the present invention.

[Explanation of symbols]

10 ... vehicle seat, 19 ... cushion pad, 30,
40 ... occupant detection sensor, 31 ... insulation sheet, 32 ... conductor coating, 33 ... terminal, 34, 44 ... protection sheet, 35 ...
Adhesive, 41 ... edge, 44a ... extension.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B29L 31:58

Claims (3)

[Claims] An occupant detection sensor in which a conductor film is formed on an insulating sheet, and a terminal is attached to the conductor film, is connected to a cushion pad of a vehicle seat with an adhesive using the conductor film as a surface to be bonded. In the mounting structure of the occupant detection sensor, the adhesive has a low-temperature embrittlement temperature of lower than −50 ° C. and a Vicat softening point having a temperature corresponding to a heat deformation temperature of the insulating sheet as an upper limit. A mounting structure for an occupant detection sensor, characterized in that the lower limit is set to ° C and the adhesive is a hot melt adhesive between the upper and lower limits. 2. The insulating sheet has a heat deformation temperature of 185.
2. The mounting structure for an occupant detection sensor according to claim 1, wherein the occupant detection sensor is a polyester resin film having a temperature in a range of from ℃ to 195 ℃. 3. The protection provided on the terminal when a part of the insulating sheet protrudes from the edge of the adhesive layer by preventing the adhesive from being interposed between the terminal and the cushion pad. By extending the sheet and interposing between the cushion pad and the adhesive layer beyond the edge of the adhesive layer, the extension of the protective sheet serves as a bending prevention stay of the insulating sheet. The mounting structure of the occupant detection sensor according to claim 1 or 2, wherein