JP4203454B2 - Load sensor mounting structure - Google Patents

Description

  The present invention relates to a mounting structure when a load sensor is attached to a predetermined member, and more particularly to a load sensor mounting structure capable of detecting a load with high accuracy.

  An automobile is equipped with an airbag device in order to ensure the safety of an occupant in the event of a collision, and a sensor for controlling the airbag device is provided in a passenger seat. This sensor is a load sensor, and can measure the weight of the occupant when seated on the seat. By providing this load sensor, it is detected that the occupant is seated on the seat, and the airbag device It is designed to control the deployment of. For example, when it is determined that a child is sitting, control is performed so that the airbag device is not deployed, or the method of deploying the airbag is made slower or faster depending on the weight of the occupant. Etc. are performed.

  The load sensor mounting structure disclosed in Patent Document 1 is disclosed. In the device disclosed in Patent Document 1, a seat cushion frame is provided on an upper rail, and the upper rail is slidably supported on a seat track. The seat cushion frame and the upper rail are each provided with a through hole communicating in the vertical direction. The threaded portion of the load sensor is inserted into both the through holes, and the nut is fastened to the threaded portion. In this mounting structure, when the occupant sits on the seat, the seat cushion frame rotates with respect to the upper rail, the distance between the seat cushion frame and the upper rail is widened, and the screw portion provided in the load sensor is pulled out. The load can be detected by the force acting in the direction. For this reason, a mechanism for rotating between the seat cushion frame and the upper rail is required, and the mechanism becomes complicated.

Therefore, instead of a load sensor that detects the force in the pulling direction, instead of a load sensor that is detected by pressing force from above as shown in Patent Document 2, for example, this load sensor is connected between the seat cushion frame and the upper rail. It is desirable to provide it in a manner that the mechanism can be simplified.
JP 2000-203324 A (paragraphs 0024 and 0029, FIG. 3) Japanese Patent No. 3268128 (paragraphs 0013 to 0017, FIG. 1)

  However, in the mounting structure provided with the load sensor described in Patent Document 2, it is necessary to tighten the nut so as not to affect the load sensor when tightening the nut to the threaded portion, and the tightening work becomes complicated. For example, if the tightening force is excessive, the detection accuracy of the load sensor decreases due to the pulling force with respect to the axial direction of the threaded portion. In addition, when the load sensor is pulled in the axial direction by tightening, the load detection origin is set in a shifted state, the load detection range is narrowed, and high-precision detection becomes difficult.

  Also, if the tightening force on the threaded part of the nut is excessive, the rotational force that rotates around the axis of the threaded part will act greatly and the load sensor will be deformed to twist around the axis, reducing the detection accuracy. To do.

  On the other hand, if tightening in consideration of tightening so as not to affect the load sensor, the tightening force may be insufficient, and rattling may occur between the load sensor and the seat cushion frame and the upper rail. Occurs, and secure attachment is hindered.

  The present invention solves the above-mentioned conventional problems, and provides a load sensor mounting structure that can obtain high detection accuracy and can securely mount the load sensor without causing backlash to the seat. The purpose is to provide.

The present invention includes a load sensor including a sensor body and a screw portion provided on the sensor body, and the load sensor is attached to the base portion by screwing a nut provided with the base portion sandwiched between the screw portion. The sensor body includes an attachment surface that faces the base, and a fastening restricting member that protrudes from the attaching surface toward the base, and the screw portion extends from the fastening restricting member to the base. A spacer that extends between the sensor body and the nut, does not overlap the fastening restricting member, and is deformable in the thickness direction, and fastens the nut to the screw portion. in the state before the total of the respective thickness of the said base spacer, the fastening restriction is set to more than the thickness dimension of the member, the threaded portion and the previously-out through hole or notch provided in the base portion Inserting the fastening regulating member, when the nut is tightened on the threaded portion with a predetermined fastening force, but said nut the spacer is deformed, characterized in that it is fastened to strike the said fastening regulating member is there.

  In the present invention, when the nut is tightened with a predetermined fastening force through the spacer, the spacer is deformed in the thickness direction, and the nut abuts against the fastening restricting member. Almost no rotation. Therefore, since the tightening of the nut can be set constant, it is possible to prevent the nut from being excessively tightened on the thread portion. As a result, the axial force and rotational force on the threaded portion do not act excessively on the sensor body, and the detection accuracy can be set high. Further, since the threaded portion can be tightened with a relatively large fastening force, the load sensor can be securely attached to the base portion.

Moreover, it is preferable that the said fastening control member is integrally formed with the said attachment surface and the said thread part .

  Thereby, since the rigidity around the threaded portion is increased, deformation of the load sensor caused by the axial force pulled in the axial direction of the threaded portion when the nut is tightened is reduced or prevented.

  It is preferable that an uneven surface facing the spacer is formed on the base.

  When a relatively large force acts on the base and a displacement occurs between the load sensor and the base, it is possible to generate a suitable friction between the spacer and the base, so that the load sensor directly It is possible to prevent a large load from acting on.

  According to the present invention, when the nut is fastened to the threaded portion, the nut can always be fastened to the threaded portion in a constant state, and therefore the detection accuracy can be prevented from being lowered due to excessive tightening of the nut. Further, the load sensor can be securely installed on the base without rattling, and an excessive force is prevented from acting directly on the load sensor.

  FIG. 1 is an exploded perspective view showing an example of a load sensor mounting structure according to the present invention, FIG. 2 is a schematic view showing an installation state of a load sensor in an automobile, and FIG. 3 is a view of the load sensor before fastening a nut. FIG. 4 is a partial sectional view showing the mounting structure of the load sensor after the nut is tightened, FIG. 5A is a plan view showing one surface around the through hole of the seat frame, FIG. (B) is XX sectional drawing of Fig.5 (a), FIG. 6 is the schematic of the internal structure of a load sensor.

  For example, as shown in FIG. 2, the load sensor mounting structure of the present embodiment is applied to a passenger seat 31 of the automobile 30. A seat frame (base) 1 and a slider 16 are provided on the seat 31, and the load sensor 10 is provided between the seat frame 1 and the slider 16. The load detected by the load sensor 10 is transmitted as an electrical signal to a predetermined control unit 40, and the control unit 40 controls the deployment operation of the airbag device 41.

  As shown in FIG. 1, the slider 16 has a support portion 16a and a leg portion 16b integrally formed. The support portion 16a is formed in a plate shape, and the bracket 15 is supported on the support portion 16a. The leg portion 16b is formed in a substantially T shape and is supported by a seat rail 17 fixed to the floor surface in the passenger compartment. The seat rail 17 has a groove 17a formed in the front-rear direction, and a lower portion of the leg portion 16b is slidably inserted into the groove 17a. When the slider 16 slides in the front-rear direction with respect to the seat rail 17, the position of the seat 31 in the front-rear direction can be adjusted. In addition, the shape of the seat frame 1, the slider 16, and the seat rail 17 of this embodiment is an example, and is not limited to this.

  As shown in FIG. 1, the load sensor 10 includes a sensor main body 11, a fastening regulating member 12, a screw portion 13, and a cable 14.

  As shown in FIG. 6, the sensor main body 11 has a detection portion 11a and a cylindrical transmission portion 11b, as in the load sensor disclosed in Japanese Patent No. 3268128 (Patent Document 2). Further, a flange-shaped receiving portion 11d is attached to the lower end peripheral portion of the detecting portion 11a, and the receiving portion 11d is joined to the lower end portion of the transmitting portion 11b. Moreover, the said detection part 11a has the same strain body as what was used for the load sensor disclosed by patent document 2, for example. The strain body is provided with a strain gauge. When a load is applied from above the sensor body 11, the deformation force of the transmission portion 11b due to the load is transmitted to the detection portion 11a via the joint portion 11s, as in the load sensor disclosed in Patent Document 2. The strain of the detection unit 11a is detected by the strain gauge.

  As shown in FIG. 1, the fastening restricting member 12 is formed in a disk shape, is provided between the mounting surface 11 c of the sensor body 11 and the screw portion 13, and is integral with the sensor body 11 and the screw portion 13. Is formed. The threaded portion 13 is formed integrally with the seating surface 12 a on the upper surface of the fastening restriction member 12 and extends toward the seat frame 1.

  The cable 14 is formed to extend from the sensor main body 11 to the control unit 40, and a load detection signal detected by the sensor main body 11 is sent to the control unit 40 via the cable 14.

  The seat frame 1 is formed by bending a metal member such as an iron plate into a U-shaped cross section. A circular through hole 1 a penetrating in the vertical direction is formed on the surface of the seat frame 1 facing the load sensor 10. When the opening dimension (diameter dimension) of the through hole 1a is D and the outer diameter dimension of the fastening restricting member 12 is C, the opening dimension D is set to be larger than the outer diameter dimension C. .

  As shown in FIG. 5B, uneven surfaces 5 a and 5 b are formed on the upper and lower surfaces of the seat frame 1. The uneven surfaces 5a and 5b are formed so as to have the same surface processing range so as to surround the periphery of the through hole 1a. As shown in FIG. 5A, the entire shape of the surface processing range is set to a quadrangular shape excluding the vicinity of the peripheral edge of the through hole 1a. The seat frame 1 is not limited to the through hole 1a, and may be a notch.

  As shown in FIG. 1, ring-shaped spacers 2 and 3 are overlapped on the upper surface side and the lower surface side of the seat frame 1. The spacers 2 and 3 have the same material and the same shape, and are formed of a material that can be crushed and deformed in the thickness direction. For example, the material of the spacers 2 and 3 can be selected from metal materials such as copper, brass, aluminum, and zinc, or may be an elastically deformable non-metallic material such as rubber and resin. As a combination of materials of the seat frame 1 and the spacers 2 and 3, it is preferable that the seat frame 1 is iron and the spacers 2 and 3 are copper or brass. The inner diameter E of the spacers 2 and 3 is set to be substantially the same as the outer diameter C of the fastening restricting member 12, and the fastening restricting member 12 is inserted into the insertion holes 2 a and 3 a of the spacers 2 and 3. Can be inserted.

  In the load sensor mounting structure of the present embodiment, the threaded portion 13 of the sensor body 11 from the lower spacer 3 side in a state where the spacers 2 and 3 are overlapped from above and below with respect to the through hole 1a formed in the seat frame 1. Is inserted. The screw portion 13 passes through the insertion hole 3 a, the through hole 1 a and the insertion hole 2 a, and the tip portion of the screw portion 13 protrudes from the upper surface of the spacer 2. The state at this time is the state shown in FIG.

  As shown in FIG. 3, the opening dimension D of the through hole 1 a is formed larger than the outer diameter dimension C of the fastening restricting member 12. Thereby, the said fastening control member 12 can be inserted in the said through-hole 1a, and can move now in the direction orthogonal to the axial direction of the screw part 13 in the said through-hole 1a. Further, each inner diameter dimension E (see FIG. 1) of each of the spacers 2 and 3 is formed so as to be able to be inserted through the fastening restricting member 12 with almost no gap. Accordingly, the fastening restricting member 12 can be inserted into the through hole 1a and the insertion holes 2a and 3a in a state where the seat frame 1 and the spacers 2 and 3 are overlapped with each other.

  In a state before the nut 4 is tightened to the threaded portion 13, when the thickness dimension of the seat frame 1 is A and the thickness dimension of the spacers 2 and 3 are both B, the thickness dimension of the seat frame 1 and the spacers 2 and 3 is The total H1 (= A + 2B) is set to be larger than the thickness dimension H2 of the fastening restricting member 12. That is, the height dimension from the attachment surface 11 c to the upper surface of the spacer 2 is higher than the height dimension of the fastening restriction member 12.

  In the state shown in FIG. 3, when the nut 4 is fastened to the screw portion 13 with a predetermined fastening force, the lower surface of the nut 4 comes into contact with the spacer 2. When the nut 4 is further tightened from the abutted state, the spacers 2 and 3 are crushed and deformed in the thickness direction, and the nut 4 abuts against the seat surface 12a of the fastening restricting member 12. At this time, as shown in FIG. 4, when the thickness dimension of the spacers 2 and 3 is B ′, the total thickness H3 (= A + 2B ′) of the seat frame 1 and the spacers 2 and 3 is fastened. It becomes the same as the thickness dimension H2 of the regulating member 12.

  By the way, when the spacer is not provided, the contact area between the nut and the seat frame is reduced, the surface pressure (force per unit area) exerted on the seat frame 1 is increased, and the sensor body 11 is locally applied. An excessive force is applied to the sensor, and the detection accuracy is lowered. In the present embodiment, by providing the spacers 2 and 3 on the upper and lower surfaces of the seat frame 1, the contact area between the spacers 2 and 3 and the sensor main body 11 even if the surface of the seat frame 1 is somewhat uneven. The surface pressure exerted on the sensor body 11 can be suppressed. Thereby, it can prevent that excessive force acts on the sensor main body 11 locally. By suppressing the surface pressure, it becomes possible to disperse the force applied to the sensor body 11, and the force acts uniformly on the sensor body 11, thereby enabling accurate detection.

  As shown in FIG. 4, when the nut 4 abuts against the seating surface 12 a of the fastening restricting member 12, the spacers 2 and 3 are not further deformed because the pressing force from the nut 4 does not increase. Therefore, even when a large fastening force is applied to the nut 4 when the nut 4 is in contact with the fastening restriction member 12, the nut 4 hardly rotates. At this time, the friction between the sensor body 11, the spacer 3, and the seat frame 1 and the friction between the nut 4, the spacer 2, and the seat frame 1 do not change. Therefore, by providing the fastening restricting member 12 between the sensor main body 11 and the screw portion 13, the upper limit of these frictional forces can be defined. Accordingly, by setting the friction between the seat frame 1, the spacers 2, 3, the nut 4, and the sensor body 11 to be moderately reduced, the axial direction of the screw portion 13 that acts on the sensor body 11 is centered. Torsion due to the rotational force can be reduced, and highly accurate detection becomes possible.

  Further, even if the nut 4 is tightened with an excessive fastening force, the nut 4 can be stopped at a fixed position where it abuts against the fastening restricting member 12, so that it is necessary to suppress the fastening force in consideration of excessive tightening of the nut 4. The load sensor 10 can be attached to the seat frame 1 without rattling.

  Further, in the present embodiment, since the fastening restricting member 12 is provided integrally with the sensor main body 11, the rigidity of the upper part of the sensor main body 11 is increased, and the screw portion 13 is pulled in the axial direction due to excessive tightening of the nut 4. Even if the axial force P acts greatly, the sensor main body 11 is difficult to deform. In this way, the tightening operation of the nut 4 suppresses an excessive force from acting on the sensor body 11, so that the load origin is not set in a state in which a large load is applied. Therefore, the load detection range is not narrowed, and highly accurate detection is possible.

  More specifically, as shown in FIG. 7, when the fastening restricting member 12 is not provided on the sensor body 11, the axial force P due to excessive tightening of the nut 4 is caused by the screw portion in the fastening work by the nut 4. When acting on 13, the mounting surface 11c of the sensor body 11 is deformed so as to be pulled upward. As a result, since the load origin of the sensor body 11 is set in a state where the load is greatly received, the load origin largely fluctuates, the detection range is narrowed, and the detection accuracy is lowered. In addition, when the load origin is set in a state where the load is acting in this way, for example, when the deformation state of the sensor body 11 changes due to a change with time, the load origin changes at the same time and the load detection accuracy decreases. To do. Therefore, in the present embodiment, the fastening restricting member 12 is integrally formed on the mounting surface 11c of the sensor body 11 as described above, thereby increasing the rigidity of the upper portion of the sensor body 11 and increasing the sensor due to the excessive axial force P. The deformation of the main body 11 can be prevented.

  Further, in the load sensor mounting structure of the present embodiment, the force generated by normal use such as when the seat 31 is slid in the front-rear direction with respect to the seat frame 1 is the uneven surface 5 a formed on the seat frame 1. , 5b and the spacers 2 and 3 are absorbed by the frictional force, and the positional displacement between the seat frame 1 and the load sensor 10 does not occur.

  In addition, when an impact is applied to the seat frame 1 and a force that moves the seat frame 1 in the front-rear direction is applied, the force is applied to the uneven surfaces 5 a and 5 b formed on the seat frame 1 and the spacer 2. , 3 while being absorbed by the frictional force between them, the inner peripheral edge of the through hole 1a of the seat frame 1 is prevented from suddenly hitting the side surface 12b of the fastening restricting member 12 of the load sensor 10, and the load sensor 10 is damaged. Thus, the inconvenience of being undetectable can be prevented.

  Further, since the opening dimension D of the through hole 1a is formed larger than the outer diameter dimension C of the fastening restricting member 12, when the impact acts on the seat frame 1, the through hole 1a is restricted from fastening. Since it does not collide suddenly with the side surface 12b of the member 12 and collides in a state where the impact force is relaxed, the load sensor 10 can be prevented from being damaged.

  The present invention described above is not limited to the above-described embodiment. For example, a spring washer may be used instead of the spacer. In this case, even if the dimension H1 and the dimension H2 before the nut are fastened are set to be the same, the seat frame and the spring washer are caused by the elastic force of the spring washer when the nut is tightened until it hits the fastening restricting member. An appropriate frictional force can be generated between the nut and the sensor body, and the same effect as in the above embodiment can be exhibited.

It is a disassembled perspective view which shows an example of the attachment structure of the weight sensor of this invention. It is the schematic which shows the installation state of the load sensor in a motor vehicle. It is a fragmentary sectional view which shows the attachment structure of the load sensor before tightening of a nut. It is a fragmentary sectional view which shows the attachment structure of the load sensor after tightening of a nut. (A) is a top view which shows one surface around the through-hole of a seat frame, (b) is XX sectional drawing of Fig.5 (a). It is the schematic of the internal structure of a load sensor. It is the schematic of the internal structure of the load sensor in which the fastening control member is not installed.

Explanation of symbols

1 Seat frame (base)
DESCRIPTION OF SYMBOLS 1a Through-hole 2,3 Spacer 4 Nut 5a, 5b Uneven surface 10 Load sensor 11 Sensor main body 11c Mounting surface 12 Fastening restriction member 12a Seat surface 13 Screw part

Claims (3)

A load sensor including a sensor main body and a screw portion provided in the sensor main body;
A mounting structure of a load sensor attached to the base by screwing a nut provided with the base sandwiched between the screw part ,
The sensor body includes a mounting surface facing the base, and a fastening regulating member protruding from the mounting surface to the base side,
The threaded portion is provided extending from the fastening restricting member toward the base side,
A spacer that is provided between the sensor body and the nut and does not overlap the fastening regulating member and is deformable in the thickness direction;
In a state before the nut is tightened to the threaded portion, the total thickness of each of the base and the spacer is set to be equal to or greater than the thickness of the fastening restricting member,
When the threaded portion and the fastening restricting member are inserted into a through hole or notch provided in the base and the nut is fastened to the threaded portion with a predetermined fastening force, the spacer is deformed and the nut is A load sensor mounting structure, wherein the load sensor is fastened until it hits the fastening restricting member. The load sensor mounting structure according to claim 1, wherein the fastening restricting member is formed integrally with the mounting surface and the screw portion . Wherein the base, the mounting structure of the load sensor according to claim 1 or claim 2, characterized in that uneven surface facing the spacer is formed.

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