JP4077761B2 - Tension detector - Google Patents

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]
In other words, in the seat belt device, when the occupant normally wears the webbing, the webbing restrains the occupant loosely in order to ease the restraint feeling 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 detection device, the webbing connection member is allowed to slide only along the surface direction of the anchor connection member fixed to the vehicle body and cannot follow the tension direction of the webbing. When the value does not match, only the component force of the tension is measured, and there is a problem that the 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]
[Patent Document 1]
JP 2002-206978 A [Patent Document 2]
US Patent Application Publication No. 2002 / 0043795A1
[Problems to be solved by the invention]
As described above, in the conventional tension detection device, when the tension direction of the webbing belt is deviated from the detection (sensitivity) direction of the strain gauge or the like, the output is different even when the tension acting on the webbing belt is the same. There is concern.
[0012]
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.
[0013]
[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 is in a sealed bag shape having a substantially circular cross section. A bag-like member that is formed and arranged so that the tension acts substantially in the direction of the center of the cross section, and is crushed and deformed by the tension; and a pressure detecting means that detects an internal pressure of the bag-like member. Yes.
[0014]
In the tension detection device according to claim 1, when longitudinal tension acts on the belt-like belt member, the bag-like member is crushed by the tension acting substantially in the center of the circular cross section (pressed by the belt member). It deforms and its internal pressure rises according to the tension. The detecting means detects the internal pressure (change) of the bag-like member, and the tension of the belt member is detected.
[0015]
Here, the bag-shaped member having a three-dimensional shape (structure) having a circular cross section acts from almost any direction in the center direction (radial directions in the cross-sectional view) because the tension acts substantially in the center direction in the cross-sectional view. The same deformation occurs for the tension to be applied. That is, when a tension of the same magnitude is applied from a direction different from the substantially central direction, the bag-like member is deformed (displaced) so that the internal pressure changes by the same amount.
[0016]
As a result, this tension detection device has a significant flexibility in sensitivity direction as compared with the conventional configuration in which the distortion in the surface direction is directly detected, regardless of the direction of tension acting on the belt member. The output of the detection means that accurately corresponds to the tension can be obtained.
[0017]
Thus, in the tension detection device according to the first aspect, the tension acting on the belt member can be detected with high accuracy.
[0018]
A tension detection device according to a second aspect of the present invention is the tension detection device according to the first aspect, characterized in that the bag-like member is disposed inside an annular portion provided in the belt member.
[0019]
In the tension detecting device according to claim 2, a bag-like member is disposed in an annular portion provided at an end portion or an intermediate portion of the belt member, and when a longitudinal tension acts on the belt member, the annular portion is For example, the bag-shaped member is pressed by being crushed (releasing the slack by bringing the opposite portion close to each other) or by moving relative to the bag-shaped member. As a result, the internal pressure of the bag-like member increases and the tension is detected. In this way, the bag-like member can be arranged with a simple structure so as to be capable of being crushed and deformed by the above-described tension toward the center.
[0020]
A tension detection device according to a third aspect of the invention is the tension detection device according to the second aspect, wherein the tension detection device is formed in a cylindrical shape and provided between the bag-like member and the annular portion, while supporting the tension. A cylindrical member that rotates around an axial center following the change in the direction of the tension, and projects from the inner surface of the annular portion in the tension direction, and penetrates the cylindrical member when tension is applied to the belt member. And a pressing member that presses the bag-like member.
[0021]
According to a third aspect of the present invention, the cylindrical member provided in the annular portion of the belt member supports the tension of the belt member, and the bag-like member is disposed in the cylindrical member. When tension is applied to the belt member, the cylindrical member follows the tension direction and rotates together with the annular portion. For this reason, even if the tension direction (attitude) of the belt member changes, the pressing member that protrudes from the inner surface of the annular portion and can penetrate the cylindrical member is maintained in the tension direction. The bag-like member is pressed by moving in the tension direction.
[0022]
As described above, in this tension detecting device, the bag-shaped member is disposed in the cylindrical member that supports the belt member tension in the annular portion of the belt member, so that the tension of the belt member is substantially centered on the bag-shaped member. It is possible to easily and compactly realize the configuration that acts on the apparatus.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
A tension detection device 10 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic overall configuration of the tension detection device 10 in a sectional view, and FIG. 2 shows a side sectional view of the tension detection device 10.
[0024]
The tension detection device 10 is applied to, for example, a three-point seat belt device mounted on a vehicle such as an automobile, and the vehicle side of a webbing belt 12 for restraining an occupant as a belt member constituting the seat belt device. The tension Ft, which is arranged at the anchor portion which is the fixed end of the webbing and acts on the webbing belt 12 in the longitudinal direction, is detected.
[0025]
As shown in FIG. 1, an annular portion 12 </ b> A is provided at the anchor side end portion of the webbing belt 12. In the present embodiment, the annular portion 12A is formed by sewing the folded end portion of the webbing belt 12 to the intermediate portion.
[0026]
The tension detection device 10 includes a cylindrical member 14 disposed in the annular portion 12A. The cylindrical member 14 is supported so as to be rotatable about an axis with respect to the vehicle body via a bearing or the like (not shown), and supports a tension Ft acting on the webbing belt 12. That is, the webbing belt 12 is supported by the vehicle body against the tension Ft via the cylindrical member 14 and the like. Further, the cylindrical member 14 rotates (rotates) around the axial center together with the annular portion 12A in accordance with a change in the acting direction of the tension Ft.
[0027]
As shown in FIG. 2, a load sensor 16 is disposed in the cylindrical member 14. As shown in detail in FIG. 3, the load sensor 16 has a flexible bag-shaped member 18 formed in a spherical shell shape (hollow ball shape), and is provided in communication with the bag-shaped member 18 and protrudes outward. A pipe member 20, a lid member 22 for closing the open end of the pipe portion 20 in an airtight state, and a signal corresponding to the internal pressure in the bag-like member 18 (tube portion 20) embedded in the lid member 22 in an airtight state. A pressure sensor 24 as a detecting means is configured as a main component. The axis of the tube part 20 faces the approximate center of the bag-like member 18.
[0028]
The inside of the bag-like member 18 and the pipe portion 20 which are sealed spaces closed by the lid member 22 is filled with a gas such as air, a liquid such as an antifreeze liquid, or both the gas and the liquid. When the bag-shaped member 18 is pressed from the outside and deformed inward, the load sensor 16 increases the internal pressure of the bag-shaped member 18 (pipe portion 20), and a signal corresponding to the change in the internal pressure is transmitted from the pressure sensor 24. This is the output configuration.
[0029]
Thereby, in this load sensor 16, as shown in FIG. 4 (A) or FIG. 4 (B), even if the acting direction of the pressing load F acting on the bag-like member 18 is different, For the load F (the same displacement when the pressing area is constant), the bag-shaped member 18 has the same internal pressure change, that is, the same output from the pressure sensor 24. Thus, the load sensor 16 is configured to have flexibility in sensitivity directionality.
[0030]
The load sensor 16 described above is inserted into the cylindrical member 14 and detects the tension Ft of the webbing belt 12. Specifically, as shown in FIGS. 1 and 2, a pressing protrusion 26 protrudes from the annular portion 12 </ b> A of the webbing belt 12 as a long pressing member in the direction of arrow A that coincides with the tension direction of the webbing belt 12. The pressing protrusion 26 is inserted through a through-hole 14 </ b> A provided through the cylindrical member 14 in the thickness direction.
[0031]
The bag-shaped member 18 of the load sensor 16 includes a tip of the pressing protrusion 26 located in the cylindrical member 14 and a sensor receiving portion 14B protruding from the inner peripheral surface of the cylindrical member 14 opposite to the through hole 14A. Slidably contact each other. Further, a gap C is formed between the outer peripheral surface of the cylindrical member 14 around the through hole 14A and the inner surface of the annular portion 12A in a state where the tension Ft is not applied to the webbing belt 12. In this state, the cylindrical member 14 and the pipe portion 20 of the load sensor 16 are configured to be substantially coaxial.
[0032]
When the tension Ft acts on the webbing belt 12, the annular portion 12A of the webbing belt 12 moves relative to the cylindrical member 14 supported by the vehicle body in the direction of arrow A (direction in which the gap C is consumed), thereby pressing the webbing belt 12. The protrusion 26 presses the bag-like member 18 of the load sensor 16. This pressing direction is adapted to face the approximate center of the bag-like member 18. Since the pressing load of the bag-shaped member 18 by the pressing protrusion 26 (the pressing amount that is the displacement of the bag-shaped member 18) corresponds to the tension Ft, the tension detecting device 10 including the load sensor 16 is The tension Ft is detected by detecting the internal pressure (change) due to the pressing.
[0033]
Further, the load sensor 16 is supported (fixed) in a non-rotatable manner with respect to the vehicle body, and as described above, the cylindrical member 14 supported so as to be rotatable with respect to the vehicle body together with the annular portion 12A in the direction indicated by the arrow B in FIG. When it rotates, it slides (relatively rotates) with the sensor receiving portion 14B and the tip of the pressing protrusion 26. For this reason, according to the change in the tension direction (posture) of the webbing belt 12, the pressing portion of the bag-like member 18 by the pressing protrusion 26 changes. As described above, the load sensor 16 does not depend on the pressing direction, that is, the tension direction. The same signal is output for the same pressing load (pressing amount).
[0034]
The tension detection device 10 described above is electrically connected to an airbag ECU (not shown), and outputs an output signal of the load sensor 16 (pressure sensor 24) to the airbag ECU. The airbag ECU compares the output signal of the load sensor 16 with a preset threshold value. When the signal is larger than the threshold value, the airbag ECU 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 the tension acting on the webbing belt 12 restraining the occupant. It is sufficiently larger than the value corresponding to Ft.
[0035]
Next, the operation of the present embodiment will be described.
[0036]
In the tension detecting device 10 having the above-described configuration, when the tension Ft is not applied to the webbing belt 12, the pressing protrusion 26 makes a slight contact (contact) with the outer surface of the bag-shaped member 18, and the internal pressure of the bag-shaped member 18 is initially set. Value.
[0037]
On the other hand, when the longitudinal tension Ft acts on the webbing belt 12, the webbing belt 12 in which the longitudinal cylindrical member 14 enters the annular portion 12A in the direction orthogonal to the tension direction is in the direction of arrow A with respect to the cylindrical member 14. Displace. Then, along with this displacement, the pressing protrusion 26 provided on the annular portion 12A presses the bag-shaped member 18 of the load sensor 16 toward the center side, and the internal pressure of the bag-shaped member 18 increases.
[0038]
In this state, the webbing belt 12 has a tension Ft supported by the cylindrical member 14 (via the vehicle body). Then, the pressure sensor 24 of the load sensor 16 outputs a signal (change) corresponding to the internal pressure change of the bag-like member 18, that is, the tension Ft, to the airbag ECU.
[0039]
The airbag ECU determines whether or not the airbag device is operable based on this signal. When the detection signal of the tension detection device 10 (load sensor 16) 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 detection signal of the tension detection device 10 is larger than the threshold value, the operation of the airbag device is prohibited regardless of other control parameters.
[0040]
Here, the bag-shaped member 18 having a three-dimensional shape (structure) formed in a substantially spherical shell shape has a tension Ft of the webbing belt 12 acting substantially in the center direction. The same applies to the tension Ft acting from each direction. That is, when the tension of the same magnitude is applied from the substantially different directions toward the center, the bag-shaped member 18 is deformed (displaced) so that the internal pressure changes by the same amount. More specifically, for example, even if the tension Ft acts from any direction indicated by a solid line, a one-dot chain line, or a two-dot chain line in FIG. 5 (even if the webbing belt 12 is pulled in any direction), the tension In the detection device 10, the internal pressure of the bag-like member 18 of the load sensor 16 changes corresponding to the tension Ft accurately, and the tension Ft can be accurately detected based on the change in the internal pressure.
[0041]
As a result, the tension detecting device 10 has a significant flexibility in the sensitivity directionality of the tension as compared with a configuration including a strain gauge that directly detects the strain in the surface direction as in the prior art, and the webbing belt 12 Regardless of the direction of tension acting on the load, the output of the load sensor 16 (pressure sensor 24) accurately corresponding to the tension can be obtained.
[0042]
As described above, the tension detection device 10 according to the present embodiment can accurately detect the tension Ft acting on the webbing belt 12.
[0043]
A load sensor 16 (bag-like member 18) is disposed in the annular portion 12A of the webbing belt 12, and the bag-like member 18 is crushed and deformed by the relative movement of the annular portion 12A with respect to the bag-like member 18 (pressing protrusion 26). Therefore, the tension detection device 10 using the load sensor 16 is realized with a simple structure.
[0044]
In particular, since the load sensor 16 is inserted into the cylindrical member 14 that is disposed in the annular portion 12A and supported by the vehicle body and supports the tension Ft, the tension detection device 10 is configured simply and compactly. Since this cylindrical member 14 rotates around the axis along with the annular portion 12A following the acting direction of the tension Ft, the moving direction of the pressing protrusion 26 by the tension Ft is always substantially coincident with the direction of the tension Ft. For this reason, the structure which makes the tension | tensile_strength of the webbing belt 12 act to the approximate center direction of the bag-shaped member 18 is implement | achieved by the simple structure. Further, by using the load sensor 16 that is flexible in the directionality of the sensitivity, there is no need to rotate the load sensor that is pressed by the pressing protrusion 26 following the cylindrical member 14, and the structure is further simplified. .
[0045]
In the above-described embodiment, the bag-shaped member 18 has a preferable configuration in a substantially spherical shell shape, but the present invention is not limited to this. For example, the bag-shaped member 18 has a cylindrical shape with both ends closed. Or a hollow spheroid.
[0046]
In the above embodiment, the bag-like member 18 is arranged in the cylindrical member 14 and pressed by the pressing protrusion 26. However, the present invention is not limited to this. For example, the annular portion of the webbing belt 12 is used. The cylindrical member 14 may not be provided in 12A, and the annular portion 12A may be loosened by the tension Ft to press the bag-like member 18 and deform the bag-like member 18 so as to be crushed. Further, the annular portion 12A, that is, the tension detecting device 10 can be disposed in the intermediate portion in the longitudinal direction of the webbing belt 12 (for example, between the anchor portion and the retractor in the seat belt device).
[0047]
Furthermore, in the above-described embodiment, the tension detection device 10, that is, the load sensor 16 (bag-like member 18) is preferably arranged in the annular portion 12A of the webbing belt 12, but the present invention is not limited to this. For example, the bag-like member 18 is sandwiched between a pressing piece provided at the end of the webbing belt 12 and a receiving part provided at the end of the vehicle body or the other divided webbing belt. Also good.
[0048]
Furthermore, in the above embodiment, the load sensor 16 (bag-like member 18) does not follow the rotation of the cylindrical member 14, but the present invention is not limited to this. For example, the load sensor 16 is a cylindrical member. It is good also as a structure which tracks (rotates) 14 rotation.
[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 cross-sectional view showing a schematic overall configuration of a tension detection device according to an embodiment of the present invention.
FIG. 2 is a side sectional view of a tension detection device according to an embodiment of the present invention.
FIG. 3 is a partially cutaway front view showing a load sensor constituting the tension detection device according to the embodiment of the present invention.
4A and 4B are diagrams showing a load sensor that constitutes a tension detection device according to an embodiment of the present invention, where FIG. 4A is a front view showing a state in which a pressing force is applied from a certain direction, and FIG. It is a front view which shows the state which made the pressing force act from another direction.
FIG. 5 is a sectional view showing a tension detection state of the webbing belt by the tension detection device according to the embodiment of the present invention.
[Explanation of symbols]
10 Tension detector 12 Webbing belt (belt member)
12A Annular part 14 Cylindrical member 18 Bag-like member 24 Pressure sensor (detection means)
26 Pressing protrusion (Pressing member)

Claims (3)

A tension detecting device for detecting a tension acting in a longitudinal direction of a belt-shaped belt member,
A bag-shaped member that is formed in a sealed bag shape having a substantially circular cross section, and is arranged so that the tension acts toward the substantially center of the cross section, and is crushed and deformed by the tension;
Pressure detecting means for detecting an internal pressure of the bag-shaped member;
A tension detection device. The tension detecting device according to claim 1, wherein the bag-like member is disposed inside an annular portion provided in the belt member. A cylindrical member that is formed in a cylindrical shape and is provided between the bag-shaped member and the annular portion, and that rotates around an axis while following the change in the acting direction of the tension while supporting the tension;
A pressing member that protrudes from the inner surface of the annular portion in the tension direction and that presses the bag-like member through the cylindrical member when tension is applied to the belt member;
The tension detection device according to claim 2, further comprising:

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