JP3289005B2 - Seating load sensor and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is, the air over that provided in the passenger seat is an automobile driver's seat seat or the front passenger's seat seat
The present invention relates to a load sensor for operating a bag and a method for manufacturing the load sensor.

[0002]

Conventionally, vehicles with Eaba' grayed to prevent failure of the occupant of the motor vehicle at the time of an automobile crash have appeared (see, for example, JP-real-Open No. 4-31056).

[0003] However, airbags for such automobiles have been developed.
Failure protection during collisions grayed operates regardless of the difference in physical strength always the pressure to inflate the Eaba' grayed a constant occupant. For example, even for infants aboard the child seat, the pressure of Eaba' grayed against adults operate in the same size, same powerful pressure and adults actuated infants, there is a risk of choking infant . In that case, since the operation start of Eaba' grayed are made from the level above change in acceleration of the vehicle, the occurrence of change in acceleration falls wheel gutter not only upon collision of the vehicle, suddenly turning, Eaba' in sudden braking, etc. The infants are at risk of suffocation if activated.

[0004] automobile load sensors equipped with such Eaba' grayed has a structure as follows.

FIG. 12 is a view showing the structure of such a conventional load sensor. FIG. 12 (a) is a top view of a mounting portion of the load sensor, and FIG. 12 (b) is a side view thereof.

In these figures, 100 is a floor, 10
0A is a recess formed in the floor to allow the elliptical plate 101 to bend, and 102 is a fixing hole to the floor 100 formed at the floor-side fixed ends 109 on both sides of the elliptical plate 101.
3 is a fixing hole for connecting to a seat leg formed at the seat leg side fixed end 108; 104 is a separation slot which allows only the seat leg side fixed end 108 to bend; 105 is a seat leg side (not a or resistance Hakuhi seen gate <br/> di) semiconductor strain gauge is positioned near the binding of both sides of the elliptical plate 101 of the fixed end 108 is.

As shown in these figures, an elliptical plate 101
Fixed ends 109 on both sides of the floor, and fixed ends 10 on the seat leg side in the center.
8 are arranged, and a semiconductor strain gauge 105 is provided by a diffusion method by mirror finishing the surface of the elliptical plate 101. Alternatively, the resistance foil strain gauge alone is bonded. When a human body load 107 is applied to the seat leg side fixed end 108, a bending stress is generated at the seat leg side fixed end 108, and a bending strain is detected by a semiconductor strain gauge 105 (or a resistance foil strain gauge). A proportional electrical output is obtained. The elliptical plate 101 has two bolts 110
To the floor 100.

FIG. 13 shows a method of manufacturing a load sensor using a conventional resistance foil strain gauge. FIG. 13A is a plan view of the strain gage alone, FIG. 13B is a side view of the strain gage alone, and FIG. 13C is a diagram showing a state of attachment to the load sensor.

First, a worker applies an adhesive 112 to an insulating film 111 at a dedicated place in advance, and superimposes a washed resistance foil 113 thereon.

Heat and pressure are applied from above and below to form a multi-layer film of uniform thickness consisting of an insulating film 111 and a resistive foil 113 by thermosetting of the adhesive 112, an exposure resist is applied to the surface of the resistive foil 113, and a strain gauge The resist is exposed using a mask having a shape, developed, and heated to form a resist film of a strain gauge on the resistance foil.

Thereafter, unnecessary portions are removed by spraying an oxidizing liquid.

Next, the insulating film 111 is cut into a prescribed size to produce a strain gauge shown in FIG.

At some later time, another worker using the strain gauge made above and at another location producing a load sensor may have a different surface 11 of the strain gauge mounting member 114.
5 is coated with an adhesive, heated and pressed, and the mounting member 114 is
Attach to

Thus, the application of the adhesive is carried out twice at a time interval, by a completely different place and by a different operator.

[0015]

[A]

(1) There are two fixed ends 109 on the floor side and two bolts
Two numbers of 10 are required.

(2) Since the width of the elliptical plate 101 is long, the number of components and the number of mounting steps increase.

(3) The mounting space becomes large. There was such a problem. [B] (1) Since the load sensor detects bending strain,
When a tilt load or bending moment load is applied to the seat,
The bending strain due to the inclination load and the bending moment load is also superimposed on the bending strain in the gravitational direction, and does not instruct the necessary electrical output of the gravitational direction human body load 107. This is because
This is because any of the strain detection methods is bending strain.

(2) If the distance between the bolt and the nut of the fixing hole 102 is loosened during a long period of use, the distance of the fixed end on the floor plate side changes, and the fixing distance, which is the basis for detecting bending strain, changes, and the load is reduced. The proportional output changes and an accurate human body load value cannot be obtained.

In the conventional method of manufacturing a load sensor, the production of the strain gauge and the operation of attaching the strain gauge to the mounting member are carried out twice at a completely different place and by another operator at a time interval. Heating and pressurization are performed.

The present invention has been made in view of the above circumstances, and has as its object to provide a seating load sensor that can accurately detect a load on a passenger's seat and can be manufactured at low cost, and a method of manufacturing the load sensor. I do.

[0021]

Attach the load detection element for measuring the boarding load of passengers per seat during a collision of the vehicle to the means for solving the problems] (1) automobile occupant seat bottom of the seat legs and between car floor
In the sitting load sensor, the load detecting element is an electric resistance.
Strain gauge using a foil cantilever beam
Attach to the side of the mounting member and angle the cantilever to the longitudinal direction
It has a Z-shape connected to the fixed end with a certain degree of
The load at the time of sitting is detected from the shear strain .

[2] The seating load sensor according to the above [1], wherein a load detecting element is attached to four of the seat legs.

[ 3 ] In the seating load sensor according to the above [ 1 ], the strain gauge mounting portion is spot-welded on both left and right ends with a Z-shaped cantilever load sensor sandwiched between reinforcing plates pressed in the vertical direction. It is characterized by being integrated.

[ 4 ] In the method of manufacturing a seat load sensor, the method comprises the steps of:
The oblique strain gauge mounting member of the cantilever load sensor to be attached is machined from a square bar with a square cross section to make it, and the production of the strain gauge and the mounting of the strain gauge to the strain sensor mounting member of the load sensor are performed simultaneously. Using a B-stage adhesive applied to both sides of the insulating film and dispersing the solvent, stacking the resistance foil and heating once,
A strain gauge is attached to the surface of the load sensor by pressurization.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a side view of a passenger seat having a load sensor according to an embodiment of the present invention, and FIG. 2 is a rear view of the passenger seat.

As shown in these figures, four seat legs 2 are provided immediately below the passenger seat 1, and a load sensor 3 is mounted between each seat leg 2 and the floor plate 4 of the automobile. That is, the load sensor 3 is attached to each seat leg 2, and a total of four load sensors are arranged. However, when the load sensor 3 for measuring the human body load when the occupant is sitting between the four seat legs and the vehicle floor plate 4 is mounted, the gap is small and the space is small.

In order to mount the load sensor 3 in such a situation, it is necessary to reduce the height of the load sensor so that it can be easily mounted even in a small space, to minimize the number of parts, and to reduce the number of mounting steps. is there.

The load applied from the seat is not a vertical load in the event of a sudden turning, sudden braking or collision of the running vehicle, but a tilting load, a bending moment in front, back, left and right of the seat. It is necessary to measure the load in the gravitational direction under the conditions described above.

Further, it is necessary that the measured values do not change even if the fixed portions on the seat side and floor plate side are slightly loosened due to long-term use.

Hereinafter, the specific structure of the load sensor of the present invention will be described.

FIG. 3 is a side view of a cantilever-shaped load sensor according to a first embodiment of the present invention, and FIG. 4 is a plan view showing a state where the load sensor is mounted.

As shown in these figures, the cantilever-shaped load sensor 3 has a seat leg side fixed end 8 and a floor plate side fixed end 9.
And a strain gauge mounting member 10 for connecting these components, so that the human body load 7 is applied to the seat leg side fixed end 8, and the floor plate side fixed end 9 is fixed to the vehicle floor plate 4.

Here, the strain gauge mounting member 10 has an angle with respect to the longitudinal direction in order to increase the mounting area of the strain gauge and increase the distance between the fixed ends 8 on the seat leg side and the fixed end 9 on the floor plate side on both sides. It is connected to the seat leg side fixed end 8 and the floor plate side fixed end 9 in advance. That is, this shape forms a Z shape when viewed from above.

Then, the strain gauge 5 is attached to the center of the thickness of both sides of the cantilever strain gauge attachment member 10, and the shear strain is detected.

When the human body load 7 is applied to the seat leg side fixed end 8, the strain gauge mounting member 10 receives a shearing force, and a shear strain proportional to the human body load 7 is generated on the side surface.
Regarding this strain, even if the distance between the fixed ends 8 and 9 changes, even if the seat is subjected to a tilting load or a bending moment load, only the load in the direction of gravity becomes a shearing force, and only the shearing strain is detected. Bending strain is a cantilever strain gauge mounting member 1
It becomes zero at the center of the thickness at the maximum on the upper and lower surfaces of 0. Since the strain gauge uses a strain gauge for detecting shear strain, slight bending strain is eliminated on the side surface, and even if a bending moment is applied to the front, rear, left and right of the seat, the measured value is not affected.

Next, a method of manufacturing a load sensor using the strain gauge of the present invention will be described.

FIG. 5 is a top view of the strain gauge mounting member, FIG. 6 is a plan view showing a state in which the strain gauge mounting surface of the strain gauge mounting member is arranged up and down on many planes, and FIG. FIG. 8 is a plan view of an insulating film to which an adhesive is applied, FIG. 8 is a diagram showing a structure for attaching a resistance foil to a strain gauge attaching member, FIG. 9 is a diagram showing a structure of the strain gauge, and FIG. 9 (b) is a top view thereof, FIG. 10 is a view showing a state where a seat leg side fixed end, a strain gauge mounting member and a floor plate side fixed end are separated, and FIG. 11 is a seat leg side fixed end. It is a figure showing the state where the strain gauge attachment member and the floor plate side fixed end were welded and integrated.

The Z-shaped cantilever shown in FIG. 4 is separated into the shape of the strain gauge mounting member 10 before the strain gauge is mounted, as shown in FIG. That is, as shown in FIG. 10, the seat leg side fixed end 8, the strain gauge mounting member 10,
Separate into three fixed ends 9 on the floor side. In the actual processing step, the seat leg side fixed end 8 and the floor plate side fixed end 9 are made of stainless steel.
Is punched out by a press machine, and the surface is machined to produce. The strain gauge mounting member 10 is manufactured by machining a stainless steel bar.

Next, the strain gauge mounting member 10 manufactured by machining from a square bar having a rectangular cross section is aligned on a large number of planes with the strain gauge mounting surface up and down, and is held by a frame or the like to maintain flatness, as shown in FIG. Line up.

In FIG. 6, 30 (1) to (30) strain gauge mounting members 10 are arranged. After cleaning the upper and lower flat surfaces of the arranged gauge mounting members 10, the insulating film 1 having heat resistance in advance in another work place shown in FIG.
1 (for example, polyimide resin film)
The pressure-curable adhesives 12 and 13 (for example, a polyimide-modified adhesive) are applied, and the insulating film 11 on both sides on which the solvent is diverged (B stage state) is placed above and below the strain gauge mounting member 10. The ultra-thin resistive foil 14 serving as the resistive element of the gauge 5 is washed and laminated. This situation is shown in FIG. These are simultaneously sandwiched between the heating / pressing plate 15 and heated / pressurized and cured to complete the mounting of the resistance foil 14 on the strain gauge mounting member 10 at a time.

After this step, it is the same as the manufacturing step of the strain gauge, but is simultaneously manufactured in each step for each of a number of strain gauge mounting members arranged. For example, an exposure resist coating, exposure, an etching process for leaving the required shape of the resistive foil material and removing the others, and finally, adjusting the resistive foil 1 with a laser cutter machine in accordance with the contour of the strain gauge mounting member 10.
4. When the polyimide resin film 11 is cut, a strain gauge 5 shown in FIG. 9 is obtained.

Furthermore, after the resistance value adjustment of the strain gauge and the circuit forming operation are completed, the side surface of the seat leg side fixed end 8, the end surface of the strain gauge mounting member 10, and the side surface of the floor plate side fixed end 9 are formed by an electron beam welding machine. The end face of the strain gauge mounting member 10 is welded at the position shown in FIG. At this time, the adhesive strength of the polyimide film and the polyimide-modified adhesive is about 300 ° C.
No adverse effects due to welding heat can be avoided since they are not lost.
Although the etching solution is an oxidizing agent, the material of the strain gauge mounting member is made of stainless steel, so that it does not rust.

Next, a measure for increasing the overload strength against twisting around the horizontal axis of the Z-shaped cantilever load sensor according to the embodiment of the present invention will be described.

FIG. 14 is a diagram showing an upper reinforcing plate and a lower reinforcing plate. FIG. 14 (a) is a diagram showing the structure of the upper reinforcing plate, and FIG. 14 (b) is a diagram showing the structure of the lower reinforcing plate. . FIG.
FIG. 15A is a view showing the entire load sensor, FIG. 15A is a plan view thereof, and FIG. 15B is a side view thereof.

As shown in FIG. 14, an upper reinforcing plate 16 pressed with a steel plate having a thickness of about 1 to 2 mm to add strength against twisting about the horizontal axis of the Z-shaped cantilever load sensor. A lower reinforcing plate 17 is provided. These are spot welded to both ends using a Z-shaped cantilever load sensor as a sandwich 1
8, 19, to form an integrated structure. When the width of the reinforcing plate is increased, the torsional strength is increased, and when the seat leg-side fixed end 8 and the floor plate-side fixed end 9 are tightened and tightened with nuts, the screw when tightening the Z-shaped cantilever load sensor is tightened. The torsion moment can be eliminated and the Z-shaped cantilever load sensor is protected. In addition, since the position where the strain gauge is attached is far from the fixed portion, the movement of the zero point at the time of measurement can be minimized in correspondence with the fact that it is not affected by the stress concentration at the time of tightening.

It should be noted that the present invention is not limited to the above-described embodiment, but various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0048]

As described above, according to the present invention, the following effects can be obtained.

(A) It is possible to provide a seating load sensor that accurately detects the load on the passenger's seat, requires a small space, and can be easily mounted.

That is, the load applied from the seat is not limited to a vertical load in the event of a sudden turning, sudden braking, or collision of the running vehicle. The influence is small, and the load only in the direction of gravity can be reliably measured.

Further, even if the fixed portions on the seat side and the floorboard side are slightly loosened due to long-term use, the measured values do not change and the reliability is high.

(B) By making the beam into a Z shape having an angle with respect to the longitudinal direction, the length of the cantilever can be increased over a wide area, and the strain gauge can be easily attached.
In addition, it is possible to reduce the thermal effect of the local welding of the welder.

(C) When the load sensor is tightly fixed with a nut, the load sensor is fixed integrally with the Z-shaped cantilever load sensor.
The torsional moment when tightening the Z-shaped cantilever load sensor can be eliminated, and the Z-shaped cantilever load sensor is protected.

(D) In manufacturing the seating load sensor, the number of mounting steps can be reduced with the minimum number of parts.

[Brief description of the drawings]

FIG. 1 is a side view of a passenger seat having a load sensor according to an embodiment of the present invention.

FIG. 2 is a rear view of a passenger seat having a load sensor according to the embodiment of the present invention.

FIG. 3 is a side view of a cantilever-shaped load sensor according to the first embodiment of the present invention.

FIG. 4 is a plan view showing a situation in which a cantilever-shaped load sensor according to the first embodiment of the present invention is mounted.

FIG. 5 is a top view of a strain gauge mounting member according to the first embodiment of the present invention.

FIG. 6 is a plan view showing a state in which the strain gauge mounting surface of the strain gauge mounting member according to the first embodiment of the present invention is vertically aligned on a large number of planes.

FIG. 7 is a plan view of an insulating film coated with an adhesive in a B-stage state.

FIG. 8 is a view showing a structure for attaching a resistance foil to a strain gauge attachment member.

FIG. 9 is a view showing a structure of a strain gauge.

FIG. 10 shows a seat leg side fixed end, a strain gauge mounting member,
It is a figure showing the state where the floor board side fixed end was separated.

FIG. 11 is a view showing a state where a seat leg side fixed end, a strain gauge mounting member, and a floor plate side fixed end are welded and integrated.

FIG. 12 is a view showing the structure of a conventional load sensor.

FIG. 13 is an explanatory diagram of a method of manufacturing a load sensor using a conventional strain gauge.

FIG. 14 is a diagram showing a structure of a reinforcing plate of a Z-shaped cantilever load sensor showing an embodiment of the present invention.

FIG. 15 is a diagram illustrating an entire Z-shaped cantilever load sensor according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Occupant seat 2 Seat leg 3 Load sensor (load detection element) 4 Automobile floor plate 5 Strain gauge 7 Human body load 8 Seat leg side fixed end 9 Floor plate side fixed end 10 Strain gauge attachment member 11 Insulation film 12 Strain gauge attachment member Heating and pressure-curing adhesive between the resistance 13 Heating and pressure-curing adhesive between the resistance foil 14 Resistance foil 15 Heating / pressing plate 16 Upper reinforcing plate 17 Lower reinforcing plate 18, 19-point welding

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI G01L 1/22 G01L 1/22 L (58) Investigated field (Int.Cl. ⁷ , DB name) G01G 19 / 12,19 / 44,19 / 52 G01G 3/14 G01B 7/16 G01L 1/22 B60N 2 / 00,5 / 00 B60R 21/00

Claims (4)

(57) [Claims] 1. A seating load sensor for mounting a load detecting element between a seat leg below a passenger seat of an automobile and a floor plate of an automobile and measuring a riding load of each passenger seat at the time of an automobile collision.
The load detecting element is a strain gauge using an electric resistance foil.
To the side of the cantilever strain gauge mounting member
Connecting the cantilever with the fixed end at an angle to the longitudinal direction.
No tied Z-shape, shearing load when the human body is sitting
A seating load sensor characterized in that it is detected only from the seat. 2. The seat load sensor according to claim 1, wherein a load detecting element is attached to four of said seat legs. 3. The seat load sensor according to claim 1 , wherein the strain gauge mounting portion is formed by sandwiching a Z-shaped cantilever load sensor in a sandwich manner with a reinforcing plate pressed up and down and spot welding right and left ends thereof. A seating load sensor characterized in that it is formed into a structure. 4. A seat leg under a passenger seat of an automobile and an automatic
The oblique strain gauge mounting member of the cantilever load sensor to be installed between the car floor plates is machined from a square cross-section bar, and the machine is manufactured. The strain gauge is manufactured and the strain gauge is mounted on the strain sensor mounting member of the load sensor. At the same time, use a B-stage adhesive applied to both sides of the insulating film and allowing the solvent to emanate, use a layer of resistive foil and heat and press once to attach a strain gauge to the surface of the load sensor. A method for manufacturing a seating load sensor, which is a feature.