JP2005017008A - Apparatus for detecting tensile force - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire a tensile force detecting apparatus capable of accurately detecting the tensile force acting on a belt member. <P>SOLUTION: The tensile force detecting apparatus 10 is provided with a base member 14 for supporting the tensile force of a webbing belt 12, acting via a spindle 18 and a bearing member 16; a distortion gauge 20 mounted to the base member 14 for outputting a signal corresponding to the force of the base member 14 in the direction of arrow A; and a magnetic sensor 24 for detecting the angular displacements of a magnet 22 and the magnet 20 rotated with the spindle 18, in such a way as to follow attitude changes to the base member 14 of the webbing belt 12. By correcting the output of the distortion gauge 20 using an angle θ, formed by the direction of the tensile force with respect to the direction of the arrow A, the output of the magnetic sensor 24, it becomes possible to accurately detect the tensile force, regardless of the direction of its action. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tension detection device that detects the tension of a belt member such as a webbing belt constituting a seat belt device of a vehicle.
[0002]
[Prior art]
A vehicle such as an automobile is equipped with a so-called seat belt device that restrains the body of an occupant seated in a seat with a long belt-like webbing belt. In addition, when the vehicle suddenly decelerates, the vehicle is inflated and deployed in front of the occupant seated in the seat, and the body of the occupant trying to move to the vehicle front side by inertia A so-called airbag device is mounted.
[0003]
In addition, the above-described seat belt device may be used not only for restraining a passenger's body but also for fixing a child seat for a child occupant seated on the seat, for example.
[0004]
By the way, when the child seat is fixed on the seat, it is preferable that the airbag device corresponding to the seat with the child seat fixed does not operate. For this reason, the vehicle is usually provided with a switch for prohibiting the operation of the airbag device, and when the child seat is fixed to the seat, the driver operates the switch to operate the airbag device. It is forbidden. However, in the configuration including such a manually operated switch, the switch operation must be performed every time the child seat is attached / detached, and the switch operation is complicated.
[0005]
Therefore, there is a need for a detection device for automatically detecting the presence or absence of a child seat and prohibiting the operation of the airbag device. A seat belt tension measuring device (hereinafter referred to as a tension detecting device) that detects whether or not a child seat is attached based on the tension acting on the webbing belt is known (see, for example, Patent Document 1).
[0006]
That is, in the seat belt device, when the occupant normally wears the webbing belt, the webbing belt restrains the occupant loosely in order to relax the sense of restraint of the occupant, and the tension acting on the webbing belt is small. On the other hand, in a state where the child seat is mounted, the seat belt device firmly holds and holds the child seat in order to prevent the child seat from moving due to vehicle acceleration, and the tension acting on the webbing belt is large. For this reason, the presence or absence of the child seat can be detected by the magnitude of the tension acting on the webbing belt.
[0007]
The tension detecting device described in Patent Document 1 is installed in the anchor portion of the seat belt device, and in order to detect the tension acting on the webbing belt, the anchor connecting member and the webbing connecting member can be slid by the tension. The sensor plate is pressed and deformed by connecting and rotating an arm spring by the slide, and the deformation is measured by a strain gauge. The output of this strain gauge corresponds to the webbing tension.
[0008]
However, in this tension detecting device, the webbing connecting member is allowed to slide only along the surface direction of the anchor connecting member fixed to the vehicle body and cannot follow the tension direction of the webbing. When the directions do not coincide with each other, only the component force of the tension is measured, and there is a problem that an accurate tension cannot be detected.
[0009]
There is also known a configuration in which a strain gauge is attached to a metal plate that is installed in an anchor portion of a seat belt device and is fixed to a vehicle body at one end and on which a webbing belt is wound at the other end (for example, Patent Documents). In this case as well, when the surface direction of the metal plate (the strain gauge sensitivity direction) and the tension direction do not match, only the component force of the tension is measured, and an accurate tension is detected. There was a problem that could not.
[0010]
Therefore, a configuration in which the webbing connecting member and the metal plate (base member) are supported so as to be angularly displaceable following the change in the tension direction of the webbing belt so that the surface direction thereof coincides with the tension direction of the webbing belt is considered. (For example, see Patent Document 3). In this configuration, since the base member provided with the strain gauge and the like is pulled in the substantially plane direction by the tension, the tension of the webbing belt can be detected with relatively high accuracy.
[0011]
However, in the configuration described in Patent Document 3, the base member is held along a predetermined direction by the urging force of the web washer or the coil spring, and is angularly displaced against the urging force, thereby causing the tension of the webbing belt. In order to follow the direction, in other words, a part of the tension (component force) is used to resist the urging force in a direction different from the tension direction, so that the surface direction of the base member can be completely matched with the tension direction. Can not. Further, since the flat base member is angularly displaced with respect to the vehicle body, it is difficult to set the displacement amount (angle) large. As a result, the base member is poorly tracked in the tension direction, and there is a limit to improving the tension detection accuracy.
[0012]
[Patent Document 1]
JP 2002-206978 A [Patent Document 2]
US Patent Application Publication No. 2002 / 0043795A1 [Patent Document 3]
Japanese Patent Laid-Open No. 2002-225676
[Problems to be solved by the invention]
As described above, the conventional tension detecting device may not be able to detect the tension acting on the webbing belt with high accuracy, and it is desired to detect the tension with high accuracy regardless of the direction of the operation.
[0014]
In view of the above fact, an object of the present invention is to obtain a tension detecting device capable of accurately detecting the tension acting on the belt member.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, a tension detecting device according to a first aspect of the present invention is a tension detecting device for detecting a tension acting in the longitudinal direction of a belt-like belt member, and a base for supporting the tension of the belt member. A member, a force detecting means attached to the base member and outputting a signal corresponding to a force in a predetermined direction acting on the base member, and a signal corresponding to an angle formed by the predetermined direction and the longitudinal direction of the belt member Tension direction detecting means for outputting.
[0016]
In the tension detection device according to the first aspect, when a longitudinal tension acts on the belt member, the force detection means outputs a signal corresponding to the force in a predetermined direction acting on the base member by supporting the tension. The tension direction detecting means outputs a signal corresponding to the angle formed by the longitudinal direction of the belt member, that is, the tension acting direction with respect to the predetermined direction.
[0017]
That is, the force detection unit detects the tension or the component force of the tension, and the tension direction detection unit detects the actual direction of the tension applied to the direction of the force detected by the force detection unit. Therefore, even when the predetermined direction and the tension direction do not coincide, for example, the component force detected by the force detection means is T, and the angle formed by the direction of application of the tension Ft with respect to the direction of application of the component force T is θ. For example, a value (electrical signal) corresponding to the magnitude of the tension Ft can be calculated as Ft∝T / cos θ. As described above, in the tension detection device, the tension direction detected by the tension direction detection means is output as a correction signal for the tension component force T, so that the belt can be connected to an electrically connected device (including an external device). It is possible to calculate an accurate tension independent of the tension direction of the member.
[0018]
Thus, in the tension detection device according to the first aspect, the tension acting on the belt member can be detected with high accuracy. Needless to say, the signal corresponding to the angle formed by the predetermined direction and the longitudinal direction of the belt member includes, for example, a signal corresponding to the remainder of the angle.
[0019]
According to a second aspect of the present invention, there is provided the tension detecting device according to the first aspect, wherein the output signal of the force detecting means is corrected using the output signal of the tension direction detecting means, and the correction signal is It is further characterized by further comprising correction means for outputting as tension acting on the belt member.
[0020]
In the tension detecting device according to claim 2, for example, as described above, the correction means for correcting to Ft∝T / cos θ by using θ as an angle formed by the component force T and the acting direction of the tension Ft with respect to the direction of the component force T. Therefore, a highly accurate signal according to the magnitude of the tension Ft can be output. In addition, the number of output signals to the external device to be electrically connected can be made one, and the connection with the external device becomes easy.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
A tension detection apparatus 10 according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1A is a front view showing the substantially entire configuration of the tension detecting device 10 partially cut away, and FIG. 1B is a side view showing the tension detecting device 10 partially cut away. Is shown.
[0022]
The tension detecting device 10 is applied to, for example, a three-point seat belt device mounted on a vehicle such as an automobile. The tension detecting device 10 is disposed in an anchor portion of the seat belt device and acts on an occupant restraining webbing belt 12. The tension Ft in the longitudinal direction of the webbing belt 12 is detected.
[0023]
As shown in FIGS. 1A and 1B, the tension detection device 10 includes a base member 14. The base member 14 has a mounting portion 14A that is formed in a flat plate shape and has a lower end bent at a substantially right angle, and is fixedly attached to the vehicle body B at the mounting portion 14A.
[0024]
A shaft support member 16 is fixed to the upper end portion of the base member 14. The shaft support member 16 is formed in a U-shape in which a pair of leg plates 16A are connected by a bottom plate 16B and opened upward in a front view, and is fixed to the upper end portion of the base member 14 in the bottom plate 16B. In this state, the width direction of the base member 14 (direction perpendicular to the plate thickness direction and the vertical direction) and the opposing direction of the pair of leg plates 16A coincide.
[0025]
A support shaft 18 is bridged between a pair of leg plates 16A of the shaft support member 16, and the support shaft 18 is rotatably supported by each leg plate 16A. One end of the webbing belt 12 is locked to the support shaft 18. Specifically, an annular portion 12A is formed at one end portion of the webbing belt 12 by sewing the folded end portion of the webbing belt 12 to an intermediate portion, and the support shaft 18 is inserted into the annular portion 12A. Has been. In this state, the width direction of the webbing belt 12 coincides with the width direction of the base member 14, and an extension of the center line in the plate thickness direction of the base member 14 passes through the axis of the support shaft 18.
[0026]
The support shaft 18 is bridged between the pair of leg plates 16 </ b> A, so that the tension Ft acting on the webbing belt 12 is supported by the base member 14 via the support shaft 18 and the shaft support member 16. A strain gauge 20 as a force detection means is attached to the central portion of the base member 14 in the width direction. The strain gauge 20 outputs a force detection signal Sf corresponding to the force T acting along the main surface direction of the base member 14 indicated by an arrow A in FIG.
[0027]
The support shaft 18 is fixed to the inner surface of the annular portion 12A of the webbing belt 12 so as to follow the rotation of the annular portion 12A around the support shaft 18. That is, the support shaft 18 is configured to rotate around its axis along with the annular portion 12A in accordance with the direction of application of the tension Ft (the longitudinal direction of the webbing belt 12).
[0028]
Further, the tension detection device 10 includes a magnet 22 fixed to one end of the support shaft 18. The magnet 22 is formed in a substantially disc shape, and is disposed coaxially with the support shaft 18 outside the one leg plate 16A. The tension detection device 10 includes a magnetic sensor 24 that detects angular displacement of the magnet 22.
[0029]
The magnetic sensor 24 is fixed to the inner surface of a cover 26 that is fixed to the leg plate 16A and covers the magnet 22, and faces the magnet 22. The magnetic sensor 24 outputs a signal corresponding to the angular displacement around the support shaft 18 of the magnet 22. ing. In the first embodiment, the magnetic sensor 24 uses the angular position of the magnet 22 when the tension Ft acts in the direction of arrow A as the angular reference position, and corresponds to the angular displacement θ of the magnet 22 with respect to the angular reference position. The angle detection signal Sa is output. That is, the angle detection signal Sa output from the magnetic sensor 24 corresponds to the tension direction θ with respect to the arrow A direction.
[0030]
In the first embodiment, the magnetic sensor 24 is an MR (magnetoresistive) sensor using the magnetoresistive effect of the magnetoresistive element. The magnet 22 and the magnetic sensor 24 correspond to the tension direction detecting means in the present invention.
[0031]
The tension detection device 10 described above is electrically connected to the airbag ECU 30, and outputs the force detection signal Sf of the strain gauge 20 and the angle detection signal Sa of the magnetic sensor 24 to the airbag ECU 30, respectively. ing. The airbag ECU 30 calculates a tension value F (∝Ft) corresponding to the magnitude of the tension Ft acting on the webbing belt 12 from the force detection signal Sf and the angle detection signal Sa.
[0032]
Specifically, as shown in FIG. 2, in the airbag ECU 30, the force detection signal Sf input from the strain gauge 20, that is, the force T in the direction of arrow A acting on the base member 14, and the angle input from the magnetic sensor 24. Using the detection signal Sa, that is, the tension direction θ, the tension value F is calculated as F = T / cos θ (F = Sf / cosSa).
[0033]
Further, the airbag ECU 30 compares the tension value F with a preset threshold value. When the tension value F is larger than the threshold value, the airbag ECU 30 corresponds to a seat having a seat belt device to which the tension detection device 10 is applied. The operation of the airbag device is prohibited. This threshold value is smaller than the value corresponding to the tension Ft (range) acting on the webbing belt 12 restraining and holding the child seat on the seat, and acts on the webbing belt 12 when restraining the occupant. It is sufficiently larger than the value corresponding to the tension Ft to be applied.
[0034]
Next, the operation of the first embodiment will be described.
[0035]
In the tension detection device 10 having the above-described configuration, when the tension Ft acts on the webbing belt 12 and the webbing belt 12 is tensioned with the longitudinal direction aligned with the tension direction, the strain gauge 20 outputs a force detection signal Sf to the airbag ECU 30. At the same time, the magnetic sensor 24 outputs the angle detection signal Sa to the airbag ECU 30.
[0036]
That is, the airbag ECU 30 has a force detection signal Sf corresponding to the force T in the direction of arrow A of the base member 14 that supports the tension Ft, and an angle corresponding to the direction of action θ of the tension Ft acting on the webbing belt 12. The detection signal Sa is input.
[0037]
The airbag ECU 30 calculates the tension value F as F = T / cos θ from the force detection signal Sf and the angle detection signal Sa. Further, the airbag ECU 30 determines whether or not the airbag device can be operated based on the tension value F. When the tension value F is equal to or less than the threshold value, the operation of the airbag device is allowed on the condition that it is not prohibited by other control parameters. On the other hand, when the tension value F is larger than the threshold value, the operation of the airbag device is prohibited regardless of other control parameters.
[0038]
Here, in the tension detector 10, since the strain gauge 20 outputs the force detection signal Sf and the magnetic sensor 24 outputs the angle detection signal Sa, the direction of the arrow A coincides with the direction of action of the tension Ft. In other words, in other words, even if the force T in the direction of arrow A detected by the strain gauge 20 acting on the base member 14 is only a component of the tension Ft, the tension direction θ is corrected with respect to the component T. By outputting as information, the airbag ECU 30 can calculate the tension value F (electrical signal) as F = T / cos θ. That is, the tension detection device 10 can cause the airbag ECU 30 that is an external device to calculate an accurate tension value F that accurately corresponds to the magnitude of the tension Ft without depending on the tension direction of the webbing belt 12.
[0039]
As described above, the tension detecting device 10 according to the first embodiment can detect the tension acting on the webbing belt 12 with high accuracy.
[0040]
In addition, the tension detection device 10 includes the magnet 22 and the magnetic sensor 24 that detect the tension direction θ of the webbing belt 12 with respect to the main surface direction of the base member 14, and thus, for example, the webbing belt 12 restraining the occupant and the child seat are mounted and held. When the tension direction θ is different from the webbing belt 12 used, the tension direction θ is also used as auxiliary information (for example, auxiliary information when the tension value F is close to the threshold value), thereby further ensuring the presence or absence of the child seat. Can also be detected.
[0041]
Next, a tension detection device 40 according to a second embodiment of the present invention will be described with reference to FIG. Note that parts and portions that are basically the same as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.
[0042]
FIG. 2 shows the tension detection device 40 in a front view corresponding to FIG. As shown in this figure, the tension detection device 40 is provided with a calculation unit 42 as correction means, and the tension output from the output signals of the strain gauge 20 and the magnetic sensor 24 to the airbag ECU 30 which is an external device. Different from the detection device 10.
[0043]
That is, the calculation unit 42 is electrically connected to the strain gauge 20 and the magnetic sensor 24, respectively. Then, the calculation unit 42 obtains a tension value F (∝Ft) that accurately corresponds to the magnitude of the tension Ft from the input force detection signal Sf and angle detection signal Sa by calculation as F = T / cos θ. It has become. The computing unit 42 is also electrically connected to the airbag ECU 30 and outputs a tension value F (and a tension direction θ as auxiliary information) to the airbag ECU 30.
[0044]
Note that the airbag ECU 30 according to the second embodiment has the function corresponding to the function of the calculation unit 42, that is, the function of calculating the tension value F, except that the airbag ECU 30 according to the above-described embodiment. The configuration is the same as that of the ECU 30.
[0045]
The tension detection device 40 according to the second embodiment can output a tension value F corresponding to the tension Ft acting in the longitudinal direction of the webbing belt to the airbag ECU 30 that is an external device as described above. it can. As described above, the tension detecting device 40 according to the second embodiment can accurately detect the tension acting on the webbing belt 12, and can directly output the detected tension to an external device. it can. Therefore, the tension detection device 40 can be handled in the same manner as a normal tension sensor that outputs only a signal corresponding to the tension Ft, and there is no need to provide a calculation function corresponding to the calculation unit 42 on the airbag ECU 30 side. In addition, an increase in the number of wires connecting the calculation unit 42 and the airbag ECU 30 can be prevented.
[0046]
In each of the above embodiments, the strain gauge 20 is provided as the force detection means for detecting the force of the arrow A acting on the base member 14, but the present invention is not limited to this. For example, the base member 14 is divided into two members that can be contacted / separated in the direction of arrow A, and a load sensor pressed by the contact / separation, a distance sensor that detects contact / separation of the two members connected elastically, and the like are used as force detection means. be able to.
[0047]
Further, in each of the above embodiments, the tension direction detecting means is configured by the magnet 22 and the magnetic sensor 24 provided on the support shaft 18 that rotates around the shaft following the change in the tension direction of the webbing belt 12. The present invention is not limited to this. For example, a photoelectric rotation detector may be used as the tension direction detection means, and the position (distance) for detecting the position of the specific part of the webbing belt 12 with respect to a predetermined point of the vehicle body B. A sensor may be used. In the latter case, the support shaft 18 and the shaft support member 16 can be eliminated by simply forming a long hole corresponding to the belt width in the base member 14 and locking the webbing belt 12 to the edge of the hole. .
[0048]
Furthermore, in each of the above embodiments, the magnetic sensor 24 outputs the angle detection signal Sa corresponding to the tension direction θ with respect to the arrow A direction. However, the present invention is not limited to this, and for example, the magnetic sensor 24 May output a signal corresponding to the tension direction α (the remainder angle of the angle θ) with respect to the direction orthogonal to the arrow A direction on the paper surface of FIG. 1B, and the tension direction is determined based on other angular positions. May be. When the tension direction α is used, the tension value F may be calculated as F = T / sin α.
[0049]
【The invention's effect】
As described above, the tension detecting device according to the present invention has an excellent effect that the tension acting on the belt member can be detected with high accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic overall configuration of a tension detection device according to a first embodiment of the present invention, where (A) is a partially cutaway front view, and (B) is a partially cutaway side view. It is.
FIG. 2 is a diagram showing a relationship between a force detected by a tension detection device according to a first embodiment of the present invention and a tension direction.
FIG. 3 is a front view corresponding to FIG. 1 (A) showing a tension detecting device according to a second embodiment of the present invention.
[Explanation of symbols]
10 Tension detector 12 Webbing belt (belt member)
14 Base member 20 Strain gauge (force detection means)
22 Magnet (Tension direction detection means)
24 Magnetic sensor (Tension direction detection means)
40 Tension detection device 42 Calculation unit (correction means)

Claims (2)

A tension detecting device for detecting a tension acting in a longitudinal direction of a belt-shaped belt member,
A base member that supports the tension of the belt member;
Force detecting means attached to the base member and outputting a signal corresponding to a force in a predetermined direction acting on the base member;
Tension direction detecting means for outputting a signal according to an angle formed by the predetermined direction and the longitudinal direction of the belt member;
A tension detection device. The correction means for correcting the output signal of the force detection means using the output signal of the tension direction detection means, and outputting the correction signal as tension acting on the belt member. The tension detector according to 1.

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