JP2003240633A - Seat weight measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seat weight measuring device improved for highly accurate measurement. <P>SOLUTION: A load sensor 50 has a cantilever sensor plate 51 elastically deformed by receiving a sensor applied load, and a plurality of strain gages 54a, 54c stuck on one surface (strain measuring face) thereof. This device has an arrangement for deforming the sensor plate so that tensile strain is applied to a part of the plurality of strain gages and compressive strain is applied to the other part when the sensor plate is deformed by receiving the sensor applied load. The strain gages are stuck on a uniform surface strain region. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring seat weight including the weight of an occupant sitting on a vehicle seat. In particular, the present invention relates to a seat weight measuring device which has been improved so that more accurate measurement can be performed.

[0002]

BACKGROUND ART Vehicles are equipped with seat belts and airbags as equipment for ensuring the safety of passengers. Recently, in order to further improve the performance of seat belts and airbags, there is a trend to control the operation of the safety equipment according to the weight (weight) of the occupant. For example, the deployment gas amount and deployment speed of the airbag are adjusted or the pretension of the seat belt is adjusted according to the weight of the occupant. To do so, it is necessary to know the weight of the occupant sitting on the seat by some means. As an example of such means, load sensors (load cells) are arranged at the four corners of the front, rear, left and right under the seat, and the vertical load applied to the load cells is totaled to measure the seat weight including the occupant's weight. Has been proposed (Japanese Patent Application No. 9-156666 and Japanese Patent Application No. 10-1 by the same applicant).
21627).

[0003]

By the way, in order to obtain a durable, highly accurate and low cost seat weight measuring apparatus,
It is necessary to establish a strain detection mechanism that amplifies low strain.
Further, it is necessary to eliminate manufacturing errors of parts in the mechanism of the apparatus and measurement errors due to frictional force as much as possible.

The present invention has been made in view of the above problems, and is an apparatus for measuring the seat weight including the weight of an occupant sitting on a vehicle seat, which enables more accurate measurement. It is an object of the present invention to provide a seat weight measuring device that is improved from the above.

[0005]

Means for Solving the Problems and Embodiments of the Invention In order to solve the above-mentioned problems, a seat weight measuring apparatus according to the present invention is designed to detect a seat weight inside a vehicle seat or between a seat and a vehicle body. A device for measuring seat weight, including the weight of an occupant sitting on a seat, comprising a load sensor for receiving an associated load and converting it into an electrical signal; the load sensor being elastic under the load applied by the sensor. A sensor member that deforms, and a strain gauge fixed to one surface (strain measuring surface) of the sensor member, and when the sensor member receives a sensor applied load, one of the strain measuring surfaces of the member is provided. The flexural strength of the elastically deformable portion of the sensor member is adjusted so that a region of substantially uniform surface strain is formed in the portion, and the strain gauge is fixed to the region.

If the strain gauge is fixed (including film formation) in a region where the surface strain is substantially uniform, the strain does not change even if the position of the strain gauge is slightly displaced, so that no measurement error occurs. Therefore, the quality requirement of the manufacturing process can be lowered while ensuring the measurement accuracy.

The seat weight measuring apparatus related to the present invention is
A load related to the seat weight (including a moment, which is inserted inside the vehicle seat or between the seat and the vehicle body,
A device for measuring a seat weight including a weight of an occupant sitting on a seat, the device including a load sensor that receives a sensor applied load) and converts the electric signal into an electric signal; The sensor member is a cantilever beam that is elastically deformed in response to a stress, and a plurality of strain gauges are fixed to one surface (strain measurement surface) of the sensor member. In this case, the sensor member is deformed so that a tensile strain is applied to a part of the plurality of strain gauges and a compressive strain is applied to the other strain gauges.

The strain output of the strain gauge can be increased by connecting the strain gauge having the tensile strain and the strain gauge having the compressive strain in opposite phases on the bridge circuit. Therefore, although the measurement is performed with high sensitivity, the distortion of the sensor can be reduced and the life can be extended. Further, since the strain gauge has one strain measurement surface to which the strain gauge is fixed (for example, one surface of the plate), when the strain gauge or the wiring layer is formed by the screen printing method or the like, the film formation process is completed on one surface. Therefore, the manufacturing cost of the sensor can be kept low.

The seat weight measuring apparatus related to the present invention is
A seat sensor including a load sensor that receives a load related to the seat weight and converts the load into an electric signal, which is inserted inside the vehicle seat or between the seat and the vehicle body, and includes the weight of the occupant sitting on the seat. An apparatus for measuring; the load sensor includes: a sensor member that elastically deforms under a load applied by the sensor; and a plurality of strain gauges fixed to one surface (strain measurement surface) of the sensor member. , The sensor member is a cantilever, one end is a fixed portion, the other end is an application portion for applying a sensor applied load, the central portion is a strain gauge fixed portion, and both the fixed portion and the load application portion are reinforcing members. Is applied, and the strain is concentrated on the strain gauge fixed part.

Highly sensitive measurement can be performed by concentrating the strain on the strain gauge fixed portion.

In this aspect, a half arm is attached to the load applying portion of the sensor member, and the half arm has a relatively rigid main body which is applied to the load applying portion and a blade portion protruding from the main body. And the vane portion is provided with a point of action of a simple load (a normal load that is not a moment), and the simple load is mainly applied to the load applying portion of the sensor member through the half arm body to bend the moment. It is preferable to have a structure (folded back structure) that is transmitted as, and to apply unevenness distortion to the sensor member strain measurement surface by the folded back structure of the half arm. Further, at the simple load acting point of the half arm, there is provided a mechanism for releasing a load other than a vertical load in a sliding type or a rotating type, and the strain gauge fixing portion of the sensor member sandwiches a constricted portion in a planar shape. It is preferable to have uniform surface strain regions of compression and tension arranged symmetrically.

Even if a load other than the upper and lower sides or a rotational moment load is applied, the strain balance of the concavo-convex portion changes and the total sensitivity to the vertical load does not change. Even if there is a deviation in the direction in the horizontal plane (front-back direction of the vehicle, etc.) or if the sensor member has axial load, the error can be canceled by the compression strain gauge and the tension strain gauge, and the outputs of both strain gauges are combined. The total sensitivity is a value without error.

Further, in the seat weight measuring apparatus of the present invention, the load acting point of the half arm and the center line of the sensor member in the thickness direction are substantially on the same plane or ± 5 mm.
It is preferable that the height difference is within the range. That is, even when a frictional force (axial force) acts on the above-mentioned point of action, the arm of the moment that bends the sensor member by the frictional force is short. Therefore, the degree of bending of the sensor member due to the frictional force is small, and the measurement error is reduced.

A description will be given below with reference to the drawings. First,
The structure around the seat of the automobile will be described with reference to FIG. FIG. 9 (A) is a front sectional view schematically showing a structural example of a portion for attaching the seat to the vehicle body. FIG. 9 (B) shows
It is a side view. In addition, the arrow in a figure shows the following directions. Top: Upward direction of gravity when the body is horizontal, Bottom: Downward direction, Front: Forward direction of the vehicle, Rear: Reverse direction of the vehicle, Left: Left toward the forward direction of the vehicle, Right: Rightward.

The seat 3 is shown in FIG. The person 1 sits on the seat cushion 3a of the seat 3. The lower surface of the seat cushion 3a is supported by a steel sheet frame 5. The seat frame 5 includes parts such as a bottom plate 5a, a horizontal plate 5c, a vertical plate 5e, and a slide plate 5g. The bottom plate 5a extends so as to cover the lower surface of the seat cushion 3a. The horizontal plate 5c extends along the left and right sides of the lower surface of the bottom plate 5a. The vertical plate 5e hangs from the central portion of the lower surface of the horizontal plate 5c. The slide plate 5g protrudes to the left and right of the vertical plate 5e like a blade, and the tip portion is bent upward.

Two seat rails 7 are provided in parallel below the left and right sides of the seat 3 so as to extend in the front-rear direction. The seat rail 7 has a U-shaped cross section and has a recess 7c therein. The opening above the recess 7c is a groove 7a extending in the front-rear direction. The vertical plate 5e of the seat frame 5 is placed in the groove 7a. A slide plate 5g of the seat frame 7 is placed in the recess 7c of the seat rail 7. The slide plate 5g is slidable in the seat rail 7 in the front-rear direction.

A seat weight measuring device 9 is connected to the lower surface of the seat rail 7. The seat weight measuring device 9 has an elongated box-like outer shape extending in the front-rear direction. Details of the seat weight measuring device 9 will be described later. The seat bracket 1 is attached to the front and rear ends of the lower surface of the seat weight measuring device 9.
1 is attached. The seat bracket 11 is fixed to the seat mounting portion 13 of the vehicle body with bolts or the like.

FIG. 4 is a diagram showing the overall construction of a seat weight measuring apparatus according to one embodiment of the present invention. (A) is a plan view, (B) is a side sectional view, and (C) and (D) are front sectional views. In addition, in FIGS. 4A and 4B, a rear half portion is not shown. FIG. 5 is a perspective view of a substantially front half portion of the seat weight measuring device of FIG. FIG. 6 is a partially cutaway perspective view showing the detailed structure around the sensor plate. FIG. 7 is a plan view showing the detailed configuration of the sensor plate. FIG. 8 is a diagram showing the relationship between the sensor plate and the half arm. (A) is a plan view, (B) is a side view with no load,
(C) is a side view schematically showing a state in which a load is applied.

The seat weight measuring device 9 has an elongated base 21 as a base. The base 21 extends in the front-rear direction when attached to the vehicle body.
As shown in (C), (D) or FIG. 5, this is a pressed steel plate product having a U-shaped front cross section. The bottom portion of the cross section of the base 21 is referred to as a bottom plate 21c, and the portion that bends 90 ° from the left and right ends of the bottom plate 21c and stands up is referred to as a side plate 21a.

As shown best in FIG. 5A, the base side plate 21a has two pin holes 21 at each of the front and rear.
e, 21g is opened. The holes 21e and 21g are
It is opened so as to face the left and right side plates 21a, 21a '. The hole 21e closer to the end is formed at a position closer to the center of about 1/8 of the entire length of the base 21 from the front and rear ends of the base 21. The hole 21e is a long hole that extends vertically long.
The end of the bracket pin 27 is contained in the elongated hole 21e.

Up and down of the bracket pin 27 and the long hole 21e
There is a gap on the left and right, and normally the bracket pin 27 does not touch the inner edge of the elongated hole 21e. However, the seat weight measuring device 9 (specifically, the pin bracket 2
5 part), an excessive load is applied to the bracket pin 27 and hits the lower edge of the elongated hole 21e, and the excess load is not transmitted to the load sensor (sensor plate 51, which will be described in detail later). That is, the pin 27 and the long hole 21e are the same as the sensor plate 5
It constitutes a part of the mechanism that limits the upper limit of the load applied to 1. The main function of the bracket pin 27 is to transmit the seat weight of the pin bracket 25 to the Z arm 23.

A pin hole 21g is formed at a position slightly closer to the center of the elongated hole 21e (at a position closer to the center of about 1/10 of the entire length of the base 21). The base pin 31 passes through the hole 21g. The base pins 31 are the left and right base side plates 21.
It exists so as to bridge between a and 21a '. Retainers 33 are attached to the left and right ends of the pin 31,
The base pin 31 is fixed to the base 21. In addition,
The base pin 31 is the central axis of rotation of the Z arm 23.

The Z arm 23 is arranged inside the base 21. Regarding the planar shape of the Z arm 23, the central portion (toward the right in FIGS. 4 and 5) is divided into left and right forks (fork portion 23h),
The edge is rectangular. Side plates 23a that are folded back upward by 90 ° are formed on the left and right ends of the half of the Z arm 23 near the end. The fork portion 23h is simply a flat plate. The Z arm side plate 23a is the side plate 2 of the base 21.
Along the inside of 1a. However, both side surfaces 23a, 21
There is a gap between a.

There are also two pin holes 2 on the Z arm side plate 23a.
3c and 23e are opened. Pin hole 2 near the front and rear ends
A bracket pin 27 penetrates 3c. Pin hole 2
3c and the bracket pin 27 hardly slide.
The base pin 31 passes through the pin hole 23e near the center. The base pin 31 is the center of rotation of the Z arm 23, and there is sliding between the pin hole 23e and the base pin 31 by the amount of rotation of the Z arm 23. A perforated disc-shaped spacer 35 (see FIG. 4D, not shown in FIG. 5) is fitted between the base side plate 21a on the outer periphery of the base pin 31 and the Z arm side plate 23a.

The fork portion 23h of the Z arm 23 is approximately half the total length of the Z arm 23. The portion 23h is divided into left and right parts and extends toward the center in the front-rear direction, and the width is narrower toward the center. As shown in FIG. 6, the action portion 23j at the tip of the Z arm fork portion 23h has the upper and lower half arms 4a and 4b.
It is sandwiched between the blade portions 41a, 42a of the blades 1, 42. When a load is applied to the pin bracket 25, the Z arm 2
3 rotates slightly (up to about 5 °), and the acting portion 23j transmits the load to the sensor plate 51 via the half arms 41 and 42.

As shown in FIG. 4C or FIG. 5B (enlarged view), the pin bracket 25 has a substantially U-shaped cross section downward. The length in the front-rear direction is about 1/20 of that of the base 21, which is not so long. The upper surface 25a of the pin bracket 25 is flat, and the seat rail 7 shown in FIG. The two are firmly connected by bolting or the like.

The left and right side plates 25b of the pin bracket 25 hang down to the left and right of the bracket 25, and the lower ends thereof are bent inward. The side plate 25b is the Z arm side plate 23.
It is arranged with play inside a. Side plate 25b
The pin hole 25c is opened in the. The bracket pin 27 passes through the hole 25c. The size of the pin hole 25c is larger than the diameter of the bracket pin 27. The gap between the two absorbs dimensional errors and unexpected deformation of the seat and vehicle body.

A spring plate 29 is sandwiched between the left and right side plates 25b of the pin bracket 25 and the left and right Z arm side plates 23a. The spring plate 29 has a spring washer-like portion with a hole, and is fitted to the outside of the bracket pin 27 with a gap. This spring plate 29 is a pin bracket 25.
A centering mechanism for urging the central part toward the center is constructed. Such a centering mechanism positions the pin bracket 25 near the center of the slidable range as much as possible. By the action of the centering mechanism, the movable range of the slide mechanism and the rotating mechanism can be secured in both directions (left and right, up and down, front and rear) after the seat weight measuring device is attached.

Next, the structure around the sensor plate (sensor member) 51 will be described. First, the configuration of the sensor plate 51 itself will be described. FIG. 7 is a diagram showing a configuration example of the sensor plate of the seat weight measuring apparatus according to one embodiment of the present invention. FIG. 7 (A)
[FIG. 3] is a plan view of a sensor plate, (B) is a side sectional view schematically showing the sectional structure of the strain gauge and the wiring portion in (A), and (C) is a circuit diagram of the sensor.

An insulating layer (lower insulating layer) 52 for electrical insulation is formed on a sensor plate (spring material) 51 which is a base material of the sensor 50. A wiring layer 53 is selectively formed on the insulating layer 52. Further, a resistance layer 54 is selectively formed on the wiring layer 53 to form a strain gauge. Then, an insulating layer (upper insulating layer) 55 as a protective film for these is formed. As described above, since the electric circuit such as the resistance is directly laminated on the spring material 51, the processing cost and the assembly cost can be reduced, and the heat resistance and the corrosion resistance can be improved.

The sensor plate 51 is a rectangular plate having two constrictions as a whole. A central shaft hole 51a is opened in the central portion of the sensor plate 51. Bolt holes 51 b are opened at both ends of the sensor plate 51. A sensor 50 is formed from the peripheral edge of the central shaft hole 51a to between the central shaft hole 51a and both bolt holes 51b. In the formation area of the load sensor 50, the central shaft hole 51a and the bolt holes 51
In the region 51c between b, there are V-shaped constrictions on both sides. Due to this constriction, the sensor plate 5
Since the portion where 1 is deformed is fixed in position, the sensor 5
The position change of the surface strain of 0 is fixed and the sensitivity becomes stable.

The sensor 50 is arranged substantially symmetrically with respect to the center of the central shaft hole 51a. The four strain resistances (strain gauges) forming the sensor 50 are the bolt holes 5
Two strain resistances 54a on the tensile strain side closer to 1b (closer to the end),
54b is disposed, and two strain resistors 54c and 54d on the compression strain side are disposed near the central shaft hole 51a (close to the center). Then, the four strain resistors 54a, 54b, 5
4c, 54d so as to form a bridge circuit as shown in FIG. 7 (C), the wiring 53a, 53b, 53c, are connected by 53d. In addition, 1, 2 in the square in the figure,
Items with numbers 3 and 4 indicate terminals.

Strain resistors 54a, 54c and strain resistors 54b, 5
A sensitivity adjustment resistor 54e is arranged between 4d.
It should be noted that instead of detecting the strain of the sensor plate 51 by the strain resistors 54a, 54b, 54c, 54d, even if the deflection of the sensor plate 51 is detected by a capacitance sensor or a Hall element and the deflection is converted into a load. Good.

Next, the structure around the sensor plate 51 is shown in FIGS.
Will be described with reference to. The sensor plate 51 is the base bottom plate 2
At the center of 1c, it is firmly fixed on the column 63 by a washer 67 and a nut 68.

The half arms 41, 42 include front and rear, upper and lower 4
It is a single-piece component and is assembled so as to sandwich the front and back of the sensor plate 51 from above and below. Individual half arm 4
Since the 1 and 42 have the same shape, the upper half arm 4
1 will be described. The half arm body 41c has a rectangular plate shape, and has a mounting hole 41e in the center thereof.
(See FIG. 8B) is open. A blade portion 41a extending rearward (or frontward) and in the left-right direction is provided in a protruding manner at an edge portion near the center of the main body portion 41c. A bank-shaped fulcrum 41b extending in the left-right direction is formed on the back surface of the blade portion 41a. The tip of the fulcrum 41b is a slightly sharp ridge.

Next, the assembly structure of the upper and lower half arms 41 and 42, the sensor plate 51, and the Z arm operating portion 23j will be described. The lower surface of the main body portion 41c of the upper half arm 41 and the upper surface of the main body portion 42c of the lower half arm 42 are flat surfaces, and are fixed to the surface of the sensor plate 51 with screws 43 so that they are perfectly aligned. Upper and lower half arms 4
The blade portions 41a, 42a of the first and the second 42 are fulcrums 41b, 42.
b are facing each other. Both fulcrums 41b,
The action portion 23j of the Z arm 23 is sandwiched between 42b. The position of the fulcrum is 2 strain gauges 5
4a, 54c or 54d, 54b is located exactly in the middle (constricted portion 51c of the sensor plate 51).

Pin bracket 2 of seat weight measuring device 9
When a load is applied to 5, the Z arm 23 rotates slightly and its acting portion 23j is lifted up. The state of the sensor plate and the half arm at this time is schematically exaggerated in FIG. 8C. When the Z arm acting portion 23j is lifted, the fulcrum 41b of the upper half arm 41 is lifted. Therefore, the moment M is applied to the front-rear end of the sensor plate 51. The moment M pulls the strain gauges 54a and 54b at the front and rear ends,
The strain gauges 54c and 54d at the center are compressed. The resistance change of each strain gauge due to this is taken out as an electric signal, and the strain of the sensor plate and thus the load applied to the pin bracket 25 is measured.

Next, the operation of the structure around the sensor plate of the seat weight measuring apparatus according to one embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram for explaining the operation of the structure around the sensor plate of the seat weight measuring apparatus according to one embodiment of the present invention. (A) is a side view,
(B) is a plan view of the sensor plate, and (C) is a graph schematically showing the strain distribution on the surface of the sensor plate. The figures show the front half and center of the sensor plate. FIG. 2 is a side view for explaining the operation when an axial force (force in the front-back direction) is applied to the fulcrum of the half arm. FIG. 3 is a graph of data obtained by examining the influence of the axial force applied to the fulcrum of the half arm on the measurement data.

As shown in FIG. 1 (A), the Z arm 23 pivots slightly upward in accordance with the seat weight (FIG. 4 (B)).
), The fulcrum 41b of the blade portion 41a of the half arm 41
Lift up. A moment M is transmitted from the half arm body 41c to the sensor plate 51 according to the lifting force W. Due to the moment M, the sensor plate 51 is bent unevenly, and a region 51y where the surface strain is tensile (+) and a region 51z where the surface strain is compressed (-) are generated.

Here, as described above, the main body portion 4 of the half arms 41 and 42 sandwiching the end portion of the sensor plate 51 from above and below.
Since 1c and 42c are thick and have high rigidity, the same portion 41c,
The load applying portion 51x of the sensor plate 51 sandwiched by the 42c is hardly distorted. Further, the central portion (fixed portion 51w) of the sensor plate 51 also has a highly rigid washer 67 and column 6
Since it is sandwiched by 3 from above and below, the same portion 51w is hardly distorted.

On the other hand, the load applying section 51x and the central fixing section 51
As shown in FIG. 1B, the portion between w has a planar shape in which two substantially triangular portions are opposed to each other with a constricted portion 51c interposed therebetween. In this portion, a uniform surface strain region 51y on the tension side and a uniform surface strain region 51z on the compression side are formed. In the regions 51y and 51z, the strain gauge 54a on the tension side or the strain gauge 54c on the compression side is formed.
Is stuck.

Therefore, it is possible to increase the strain output of the strain gauge by connecting the strain gauge to which the tensile strain is applied and the strain gauge to which the compressive strain is applied in the opposite phase on the bridge circuit. Therefore, although the measurement is performed with high sensitivity, the distortion of the sensor can be reduced and the life can be extended. Further, since the strain measuring surface to which the strain gauge is fixed is one surface of the sensor plate 51, when the strain gauge and the wiring layer are formed by the screen printing method or the like, the film forming process can be performed on one surface. Therefore, the manufacturing cost of the sensor can be kept low.

If the strain gauge is fixed (including film formation) in a region where the surface strain is substantially uniform, the strain does not change even if the position of the strain gauge is slightly displaced, so that no measurement error occurs. Therefore, the quality requirement of the manufacturing process can be lowered while ensuring the measurement accuracy.

Further, by concentrating the strain on the strain gauge fixed portion, highly sensitive measurement can be performed, and even if there is a manufacturing error or an assembly error of other parts, no measurement error occurs.

Next, the axial force acting on the half arm from the Z arm 23 will be described with reference to FIG. As described above, the force W acts from the acting portion 23j of the Z arm 23 to the fulcrum 41b of the blade portion 41a of the half arm 41. Due to the structure of the half arm 23, this force W is almost the vertical force W _v . However, it is possible that the horizontal component W _h is partially mixed. Further, due to the extension or displacement of the Z arm 23, a lateral frictional force may act on the fulcrum 41b.

Regarding the force due to friction and deformation, the Z-arm acting portion 23j and the fulcrum 41b are not constrained in the axial direction (front-back direction) and have a slippery line contact structure. No axial force (miss)
You can Further, even when the applied axial force W _h, by subtracting the output of the tension side of the strain gauges 54a and the compression side 54c, a sensor plate 51
Axial stress acting on can be canceled.

FIG. 3 shows this state. The horizontal axis of the graph in FIG. 3 represents the load applied to the seat (unit: kgf), and the vertical axis represents the output of the strain gauge (unit: mV). In the output of the strain gauges on the compression side and the tension side shown in the figure, hysteresis accompanying the increase and decrease of load is clearly seen. This is because an axial force is generated between the Z arm and the half arm when the load is raised or lowered. However, the total obtained by subtracting the compression side from the tension side shows almost no hysteresis, and the data has good linearity. This is due to the axial force canceling action described above.

That is, the strain balance of the concave and convex portions changes even when a load other than the upper and lower sides or a rotational moment load is applied, and the overall sensitivity of the sensor to the vertical load does not change. That is,
Even if there is a deviation in the direction in the horizontal plane (front-back direction of the vehicle etc.),
Alternatively, even if axial load is applied to the sensor plate, the error can be canceled by the compression strain gauge and the tension strain gauge, and the total sensitivity obtained by adding the outputs of both strain gauges has a value without error.

When there is an axial force W _h , the space S (FIG. 2) between the center line of the sensor plate 51 and the half arm fulcrum 41b becomes a moment arm, and a moment of W _h × S is applied to the sensor plate 51. This causes an error factor. Therefore, in the seat weight measuring apparatus of the present invention, the load acting point 41b of the half arm 41 and the center line of the sensor plate 51 in the thickness direction are substantially on the same plane or within ± 5 mm in height difference. I have to. That is, even when a frictional force (axial force W _h ) is applied to the action point 41b, the arm of the moment for bending the sensor plate by the frictional force is short. Therefore, the degree of bending of the sensor plate due to the frictional force is small, and the measurement error is reduced.

[0050]

As is apparent from the above description, in a device for measuring the seat weight including the weight of an occupant sitting on a vehicle seat, a durable, highly accurate and low cost seat weight measuring device is obtained. be able to. Further, it is possible to provide a seat weight measuring device with less manufacturing error of parts in the mechanism of the device and measurement error due to frictional force.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an operation of a structure around a sensor plate of a seat weight measuring apparatus according to an embodiment of the present invention.
(A) is a side view, (B) is a plan view of the sensor plate, (C) is a graph schematically showing the strain distribution on the sensor plate surface. The figures show the front half and center of the sensor plate.

FIG. 2 is a side view for explaining the operation when an axial force (force in the front-back direction) is applied to the fulcrum of the half arm.

FIG. 3 is a graph of data obtained by examining the influence of the axial force applied to the fulcrum of the half arm on the measurement data.

FIG. 4 is a diagram showing an overall configuration of a seat weight measuring apparatus according to an embodiment of the present invention. (A) is a plan view, (B) is a side sectional view, and (C) and (D) are front sectional views.

5 (A) is a perspective view of a substantially front half of the seat weight measuring device of FIG. 4, and FIG. 5 (B) is FIG. 5 (A).
3 is a partial cross-sectional view taken along the left-right direction of FIG.

FIG. 6 is a partially cutaway perspective view showing a detailed configuration around a sensor plate.

FIG. 7 is a diagram showing a configuration example of a sensor plate of the seat weight measuring apparatus according to one embodiment of the present invention. 7A is a plan view of the sensor plate, FIG. 7B is a side sectional view schematically showing the sectional structure of the strain gauge and the wiring portion of FIG. 7A, and FIG. FIG. 3 is a circuit diagram of a sensor.

FIG. 8 is a diagram showing a relationship between a sensor plate and a half arm. (A) is a plan view, (B) is a side view with no load,
(C) is a side view schematically showing a state in which a load is applied.

FIG. 9A is a front sectional view schematically showing a structural example of a portion where a seat is attached to a vehicle body. (B) is a side view.

[Explanation of symbols]

1 person 3 seat 3a seat cushion 5 seat frame 5a bottom plate 5c horizontal plate 5e vertical plate 5g slide plate 7 seat rail 7a groove 7c recess 9 seat weight measuring device 11 seat bracket 13 vehicle body (seat attachment part) 21 base 21a side plate 21c bottom plate 21e Long hole (pin hole) 21g Pin hole 23 Z arm 23a Side plate 23c Pin hole 23e Pin hole 23h Fork 23j Working part 25 Pin bracket 25a Upper surface 25b Side plate 25c hole 27 Bracket pin 29 Spring plate 31 Base pin 33 Retainer 35 Spacer 41 upper Half arms 41a, 42a
Blade portion 41b Support points 41c, 42c
Body part 41e Mounting hole 42 Lower half arm 43 Screw 50 Sensor part 51 Sensor plate 51a Central shaft hole 51b Bolt hole 51c Constriction part 51w Central fixing part 51x Load applying part 51y Tensile area 51z Compression area 52 Insulating layer (lower insulating layer) 53 Wiring layers 53a, 53b, 53c, 53d Wiring 54 Resistance layer 55 Insulating layer (upper insulating layer) 54a, 54b, 54c, 54d Strain resistance 54e Sensitivity adjusting resistance 63 Column 67 Washer 68 Nut

Claims (2)

[Reference number] KP3145 [Claims] 1. A load (including a moment, hereinafter also referred to as a sensor applied load) related to a seat weight, which is inserted inside a vehicle seat or between a seat and a vehicle body, receives the load and converts the load into an electric signal. An apparatus for measuring a seat weight including a weight of an occupant sitting on a seat, the load sensor including: a sensor member elastically deformed under a sensor applied load; and one surface of the sensor member. A strain gauge fixed to the (strain measuring surface), and a substantially uniform surface strain region is formed on a part of the strain measuring surface of the sensor member when the sensor member receives a sensor applied load. As described above, the flexural strength of the elastically deformable portion of the sensor member is adjusted, and the strain gauge is fixed to the region. 2. The seat weight measuring apparatus according to claim 2, wherein tensile strain and compression uniform surface strain regions are formed on the strain measuring surface, and strain gauges are fixed to the respective regions.