JP2002029381A - Seat belt tension detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seat belt tension detector easy to mount on an existing seat belt. SOLUTION: The seat belt tension detector 100 has an upper cover 1 and a lower cover, separately. The lower cover 2 is provided with a spring member 7 and a switch part 5. A seat belt is inserted through a longitudinal gap formed when the upper cover 1 and the lower cover 2 are joined into the seat belt tension detector 100, and it thrusts a thrust portion 14 of the spring member 7 to the lower side when tension is applied thereto. This causes the spring member 7 to be elastically deformed and the thrust portion 14 to thrust push heads 15, 16 of the switch part 5 to the lower side. The lower parts of the push heads 15, 16 are provided with plane switches which conduct when the push heads 15, 16 are pushed a predetermined stroke or more down. As a result, tension is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a seat belt tension detecting device for detecting a tension applied to a seat belt.

[0002]

[Prior art]

An airbag device is provided for protecting an occupant in the event of an accident such as a collision. This airbag deploys rapidly in the event of an accident,
In order to protect the occupant, control is being performed to prevent the child from being unfolded when the infant is placed on the child seat fixed to the seat.
Therefore, an attempt has been made to control the deployment of the airbag by detecting whether or not the child seat is fixed to the seat by detecting the tension applied to the seat belt for fixing the child seat to the seat.

[0003] As a seat belt tension detecting device used for such purpose and other purposes, for example,
Those described in International Publication WO99 / 122012 are known.

[0004] FIG. 10 shows the outline. The seatbelt tension detecting device 50 is attached to a vehicle body structure 51 by bolts 52. An end portion 56 of a seat belt 55 is fixed to a hole 54 of an anchor member 53 attached to the vehicle body structure 51 at the same time as the seat belt tension detecting device 50 by a bolt 52.

[0005] The substrate 57 of the seat belt tension detecting device 50
, A leaf spring 58 and a load sensor 59 are fixed.
After passing over the leaf spring 58, the seat belt 55 is drawn out of the seat belt tension detecting device 50 through a hole 60 provided in the substrate 57. Note that FIG.
In the figure, 61 is a cover, 62 is a spacer, and 63 is a wiring of the load sensor 59.

[0006] When tension is applied to the seat belt 55, the seat belt 55 pushes down the leaf spring 58, whereby the load sensor 59 receives a load. Therefore, by detecting the output of the load sensor 59, the seat belt 55
Can be detected.

[0007]

However, FIG.
However, the seat belt tension detecting device as described above has the following problems. A first problem is that such a seat belt tension detecting device is difficult to attach to an already installed seat belt. That is,
Since the system is shared with the seatbelt anchor, when attaching to an already installed seatbelt, the anchor portion must be replaced, which complicates the construction.

A second problem is that since the system is shared with the seat belt anchor, it can be set only on the window side of the seat where the seat belt anchor is normally provided.

A third problem is that the load applied to the load sensor 59 increases as the tension applied to the seat belt increases, so that the load sensor 59 and the leaf spring 58 can withstand a large load. It is necessary.

The present invention has been made in view of such circumstances, and can be easily attached to an existing seat belt, and the attachment position can be freely selected, and a large tension is applied to the seat belt. Even in such a case, it is an object to provide a seat belt tension detecting device in which a large load is not applied to a load sensor.

[0011]

According to a first aspect of the present invention, there is provided an apparatus for detecting a tension applied to a seat belt, comprising a first housing and a second housing. , First
The housing has a sensor in which the pressed portion moves by being pressed, thereby changing the physical characteristic value, and a sensor pressing portion, and the sensor pressing portion is attached in a direction away from the sensor. An elastic member having a force is provided, and by combining the first housing and the second housing,
A hole through which the seat belt is inserted in the front-rear direction between these housings is formed, and the seat belt passes through the hole on one side and contacts the opposite side of the sensor of the elastic member, and the hole on the other side. A seat belt tension detecting device (Claim 1) characterized in that the seat belt tension detecting device is configured to be inserted so as to come off.

When the seat belt tension detecting device of this means is installed, the seat belt is sandwiched between the first and second housings in a state where the first housing and the second housing are separated. Thus, the first housing and the second housing are connected. Then, the seat belt is in a state of being sandwiched between the first housing and the second housing, and is inserted into the housing through holes formed in front and rear between the housings. . In this way, the seat belt tension detecting device of the present means can be easily installed on an existing seat belt, and can be installed at an arbitrary position on the seat belt.

In the seat belt tension detecting device of this means, when tension is applied to the seat belt, the seat belt comes into contact with the hole on one side, the elastic member, and the hole on the other side in this order. The elastic member is pressed in a direction opposite to the urging direction. Therefore, the elastic member is elastically deformed, and the sensor pressing portion presses the sensor. Therefore,
Since the physical characteristic value of the sensor changes according to the tension, the seat belt tension can be detected by detecting the physical characteristic value.

[0014] A second means for solving the above-mentioned problems is as follows.
In the first means, when the seat belt inserted into the hole becomes linear, the elastic member is within an elastically deformable range, and the pressed portion of the sensor is within a movable range. Wherein the positions of the hole, the sensor pressing portion, and the pressed portion of the sensor are defined (claim 2).

Since the seat belt is restrained by two holes formed before and after the first and second housings, when a large tension is applied, a straight line connecting the two holes is formed. (To be linear in this means means to have a shape along such a straight line).

In this means, when the elastic member is pressed against the seat belt in such a state, the elastic member is within the elastically deformable range and the pressed portion of the sensor is within the movable range. Thus, the positions of the hole, the sensor pressing portion, and the pressed portion of the sensor are determined.
When the seat belt is in such a state, the pressing force does not increase even if the tension is further applied. Therefore, according to this means, the pressing force applied to the elastic member and the sensor is limited, and therefore, it is not necessary to make these members withstand a high load.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing an embodiment of a seat belt tension detecting device according to the present invention, in which (A) is a partial cross section of (B) cut along line BB and viewed in the direction of the arrow. Perspective view, (B) is a cross-sectional view of (A) cut along line AA and viewed in the direction of the arrow, and (C) is a part of (B) cut along line CC and viewed in the direction of the arrow. The sectional perspective view is shown.

FIG. 2 is a perspective view showing a state in which the seat belt tension detecting device according to the present invention is disassembled into two parts. FIG.
FIG. 3 is a circuit diagram of a switch unit of the seat belt tension detecting device according to the present invention. FIG. 4 is an enlarged view of the switch unit. FIG. 5 is a diagram showing another configuration example of the switch unit. FIG. 6 is a diagram showing an operation relationship between the seat belt and the spring member of the seat belt tension detecting device according to the present invention.

Hereinafter, the configuration of the seat belt tension detecting device according to the present embodiment will be described. As shown in FIG. 2, the seatbelt tension detecting device 100 has an upper lid 1 (second housing) in which the plastic outer shape is substantially rectangular and the length of the short side is slightly wider than the width of the seatbelt. ) And lower lid 2
A switch unit 5 including a diaphragm 3 and a surface switch 4 is fixed to a bottom surface in the lower cover 2. A spring member 7 that pushes up the seat belt 6 with an urging force and presses the surface switch 4 when strongly pressed down from the seat belt 6 is provided near the switch unit 5 (see FIG. 1A). .

The surface switch 4 includes a first surface switch 10 and a second surface switch 11, which are respectively pressed by a first pressing portion 8 and a second pressing portion 9 described later. Each of the surface switches 10 and 11 is a plate-like electrode, and has surface electrodes 12 and 13 arranged to be in contact with each other when the first pressing portion 8 and the second pressing portion 9 are pressed. ing.
That is, the surface electrode 12 and the surface electrode 13 are held in a non-contact manner at a predetermined interval (see FIG. 4), and are brought into contact with each other by a pressing force from above, so that the surface switch 4 is turned on. Have been.

As shown in FIG. 3, the first surface switch 10
Are electrically connected in parallel with the resistor R1, and the second surface switch 11 is also electrically connected in parallel with the resistor R3. The first surface switch 10 and the second surface switch 11 are electrically connected in series via a resistor R2. The terminal A, which is an external connection terminal, is electrically connected to the contact F, and the terminal B, which is an external connection terminal,
It is electrically connected to the contact C. The A terminal and the B terminal are electrically connected by a harness H to a power supply mounted on the vehicle.

The diaphragm 3 is an elastic member made of urethane, which is pressed close to a surface switch 4 so as to be pressed by a pressing portion 14 described later of the spring member 7 and transmit the pressing force to the surface switch 4. And two push heads of the same height, namely a first push head 15 and a second push head.
A push head 16 is formed to project from the surface of the diaphragm 3. That is, the gap between the first push head 15 and the pressing portion 14 described below, the second push head 16,
The clearance between the pressing portion 14 and the pressing portion 14 described later is equal to each other. Just on the back side of each position of these push heads 15 and 16, a first pressing portion 8 and a second pressing portion 9 having different heights are formed as thick portions, respectively.
The switches are arranged to face the surface switch 10 and the second surface switch 11 at a predetermined interval.

As shown in FIG. 4, a gap distance t1 is provided between the first pressing portion 8 and the first surface switch 10, and a gap distance t2 is provided between the second pressing portion 9 and the second surface switch 11. Each is formed. Note that t2 is larger than t1 (t2
> T1). The first push head 15 and the second push head 16 are pressed by the pressing force of the pressing unit 14, and the first pressing unit 8 is pressed.
And the second pressing portion 9 are pressed in the direction of the surface switch. The longer the pressing stroke (moving distance by which the pressing portion is pressed from the position where no load is applied), the greater the load applied. In this case, the first surface switch 10 is set to, for example, 3 kg.
The diaphragm 3 including the gap distances t1 and t2, which is made conductive by the pressing force of f (Kirogaku weight) and the second surface switch 11 is made conductive by the pressing force of, for example, 7 kgf (Kirogaku weight).
Is configured.

As shown in FIG. 2, the spring member 7 has a substantially U-shape, and has a lever-shaped pressing portion 14 at one end and a supporting portion 18 at the other end via a coil spring 17. The pressing portion 14 of the spring member 7 is provided so as to keep a constant distance from the first push head 15 and the second push head 16 of the switch unit 5 fixed to the bottom surface of the lower cover 2. The support portion 18 is fixed to the bottom surface of the lower lid 2 with an adhesive, various fixing members, or the like.

The inside of the upper cover 1 has a width and a smooth inclined surface such that the seat belt 6 can smoothly move between the spring member 7 and the upper cover 1 when joined to the lower cover 2. The recess 2 having the first inclined surface 19 and the second inclined surface 20
1 (see FIG. 1A). In addition, top cover 1
In the two opposite end portions on the side where the later-described engaging piece 22 is not formed, the introduction groove 2 having a width and a smooth inclined surface for smoothly introducing the seat belt 6 is provided.
3 and 24 are formed.

Similarly, the seat belt can be smoothly introduced into two opposing ends of the lower lid 2 where the concave fitting portion 25 is not formed so as to correspond to the introduction grooves 23 and 24 of the upper lid 1. The introduction grooves 26 and 27 are formed even with a wide width and a smooth inclined surface. Also, the concave portion 21 of the upper lid 1
A spring groove 28 for accommodating the coil spring 17
(See FIG. 1A).

The upper lid 1 is formed with an engaging piece 22 for fitting with the lower lid 2 extending from two opposing ends. Two holes 29 are formed. On the other hand, in the lower lid 2, groove-like concave fitting portions 25 for accommodating the engaging pieces 22 are formed on both side surfaces, and two claw portions 30 that can be fitted into the holes 29 of the engaging pieces 22. Is protruding.

Since the upper lid 1 and the lower lid 2 configured as described above are used, the seat belt 6 at a predetermined position of the seat belt 6, for example, near a shoulder anchor (not shown) or near a lap anchor (not shown) is moved downward. In a state in which the seat belt 6 is disposed so as to cover the pressing portion 14 of the spring member 7 provided in the lid 2 and the seat belt 6 is properly placed on the introduction portions 26 and 27 formed in the lower lid 2. ,
When the upper lid 1 is put on and pressed against each other, the holes 29 provided in the engaging piece 22 and the claws 30 protruding from the concave fitting portions 25 are automatically engaged, so that the seat belt 6 can be easily and reliably fixed. It can be joined in a sandwiched state.

The seat belt 6 is led out from the seat belt tension detecting device 100 so that the seat belt tension detecting device 100 attached to a predetermined place of the seat belt 6 does not slip down or change its position. The seatbelt portion adjacent to the seatbelt tension detecting device 100 and the seatbelt 6 before being introduced into the seatbelt tension detecting device 100 and closest to the seatbelt tension detecting device 100 It is preferable that one clip (not shown) is arranged so that the seatbelt tension detecting device 100 does not largely move.

Next, the operation of the seat belt tension detecting device 100 according to the present embodiment will be described. The seat belt tension detecting device 100 is attached to a predetermined place of the seat belt 6, for example, near a shoulder anchor (not shown) as described above. When the tension of the seat belt 6 rises, the seat belt 6 (FIG.
(A), see FIG. 6) is going to stretch straight (FIG.
, The pressing portion 14 of the spring member 7 is pressed down in the direction of the surface switch 4.

When the pressing force is greater than a predetermined pressure, specifically, the urging force generated by the restoring force of the coil spring 17 of the spring member 7, the pressing portion 14 of the spring member 7 is moved to the first push head 15 and the second push head 15. The push head 16 is contacted and pressed almost simultaneously. Thereby, the first push head 15 and the second
The push head 16 is pressed down substantially uniformly in the direction of the surface switch 4 by the pressing force from the pressing portion 14.

The first pressing portion 8 is larger than the second pressing portion 9 by (t2).
Since the projection is formed by -t1), the pressing stroke until the first surface switch 10 is turned on is smaller than the pressing stroke until the second surface switch 11 is turned on. Therefore, the first surface switch 10 is turned on with a load of about 3 kgf. Next, when the tension of the seat belt 6 is increased and a larger load is applied to the pressing portion 14 and the pressing portion 14 is further pressed toward the surface switch 4, the second pressing portion 9 is pressed by (t2−t1). Then, the second surface switch 1
Press 1 to make it conductive. In this case, the second surface switch 11
Conducts with a load of about 7 kgf.

It should be noted that even if a larger tension acts on the seat belt 6, the seat belt 6 only straightens, so there is an upper limit on the pressing force acting on the pressing portion 14 from the seat belt 6, and the upper limit is not less than this upper limit. The pressing force is surface switch 4.
And no durability problem occurs. On the other hand, in the conventional seat belt tension detecting device, the rigidity of the seat belt tension detecting device must be increased in accordance with the seat belt tension, and there is a problem of durability.

In the above embodiment, the diaphragm is used to keep the surface electrodes 12 and 13 of the main switch 4 apart in a steady state.
As shown in FIG. 7, a leaf spring may be used instead of the diaphragm. In FIG. 5, a first leaf spring 33 is provided near the first surface switch 10. The first leaf spring 33 has a U-shape, one end of which has a first push head 31 formed to protrude upward, and the other end thereof has a first push head 31 formed to protrude downward. It has a pressing portion 32.
The first pressing portion 32 is almost in contact with the first surface switch 10, and a gap distance t3 is formed between the first push head 31 and the pressing portion 14.

Similarly, a second leaf spring 34 is provided near the second surface switch 11. This second leaf spring 34
Has a U-shaped shape, one end of which has a second push head 35 formed to protrude upward, and the other end has a second pressing portion 36 formed to protrude downward. ing. Second
The pressing portion 36 is almost in contact with the first surface switch 11, and a gap distance t4 is formed between the first push head 35 and the pressing portion 14. Note that t4 is larger than t3 (t4> t3). The operation of the switch unit thus formed is the same as that shown in FIG. 4, and the description is omitted here.

FIG. 7 shows an example of a circuit for detecting ON / OFF of the first surface switch and the second surface switch of the seat belt tension detecting device thus configured. The terminal of the switch unit 5 is connected to an ECU (Electric Control Unit).
One terminal is connected to the ground potential of the ECU. A power supply voltage Vc is applied to the other terminal via a resistor Rc, and the voltage Vsw at that terminal is converted into a digital value by an A / D converter and read by the MPU.

Assuming that the combined resistance of the switch section 5 is R, Vsw = Vc * R / (R + Rc). Therefore, by detecting Vsw, it is possible to detect a combination of the combined resistance R and the ON / OFF of the surface switches 10 and 11.

When R is larger than a specified value, it is determined that the switch system including the wire harness is disconnected. When R is smaller than the specified value, it is determined that the switch system including the wire harness is short-circuited. Judgment is also possible.

In the above embodiment, the tension is detected in two stages by using two surface switches. However, a large number of surface switches are provided, and the operating points thereof are shifted so that the tension is multi-staged. Can be detected.

Further, if a sensor whose resistance continuously changes in accordance with the position of the push head is used instead of the surface switch, the tension can be detected in an analog manner. The first method is to use a sensor having a contact portion made of a comb-shaped resistor 41 as shown in FIG. As shown in FIG. 8, the contact portions connected to both terminals have a comb-like shape, and have such a configuration that the comb teeth of each other mesh with each other. Therefore, the resistance value between the two contacts increases or decreases depending on the interval between the two contacts. Therefore, by measuring the resistance between the two contacts, the distance between the two contacts can be determined, and the seat belt tension can be detected from this.

Another method is as shown in FIG.
This is a method using a sensor having a structure in which the shape of the push head 42 pressed by 4 on the contact 43 side is oblique, and the contact 43 contacts the resistor 44. Pressing part 1
4, when the push head 42 is pressed, the contact 43
Contact the resistor 44 sequentially from the right side of FIG. The resistance value between the contact 43 and the terminal provided on the resistor 44 changes according to the position of the push head 42. By measuring this resistance value, the position of the push head 42 can be determined, and the seat belt tension can be detected from this. .

[0042]

As described above, according to the first aspect of the present invention, the seat belt tension detecting device can be easily installed on an existing seat belt, and the seat belt tension detecting device can be installed easily. Can be installed at any position.

In the invention according to the second aspect, in addition to this, it is not necessary to make the elastic member and the sensor withstand a high load.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a seat belt tension detecting device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state where the seat belt tension detecting device shown in FIG. 1 is disassembled into two parts.

FIG. 3 is a circuit diagram relating to a switch unit of the seat belt tension detecting device shown in FIG.

FIG. 4 is an enlarged view showing a switch section of the seat belt tension detecting device shown in FIG. 1;

FIG. 5 is a diagram illustrating another configuration example of the switch unit.

FIG. 6 is a diagram showing an operation relationship between a seat belt and a spring member of the seat belt tension detecting device shown in FIG.

FIG. 7 is a diagram showing an example of a circuit for detecting ON / OFF of a first surface switch and a second surface switch of the seat belt tension detecting device.

FIG. 8 is a diagram illustrating an example of a sensor that detects a seat belt tension in an analog manner.

FIG. 9 is a diagram illustrating another example of a sensor that detects a seat belt tension in an analog manner.

FIG. 10 is a diagram showing an outline of a configuration of a conventional seat belt tension detecting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Upper lid, 2 ... Lower lid, 3 ... Diaphragm, 4 ... Surface switch, 5 ... Switch part, 6 ... Seat belt, 7 ... Spring member, 8 ... 1st press part, 9 ... 2nd press part, 10 ... No. 1-side switch, 11 ... second-side switch, 12, 13 ... surface electrode,
14 ... Pressing part, 15 ... First push head, 16 ... Second push head, 17 ... Coil spring, 18 ... Support part, 19 ...
1st inclined surface, 20 ... 2nd inclined surface, 21 ... concave part, 22 ... locking piece, 23, 24 ... introduction groove, 25 ... concave fitting part, 26, 27
... Introduction groove, 28 ... Spring groove, 29 ... Hole, 30 ... Tail part,
31: first push head, 32: first pressing portion, 33: first leaf spring portion, 34: second leaf spring portion, 35: second push head, 36: second pressing portion, 41: comb teeth Resistor, 42 ...
Push head, 43 contact, 44 resistor, 100 seat belt tension detector

Claims (2)

[Claims] An apparatus for detecting a tension applied to a seat belt, comprising: a first housing and a second housing, wherein the first housing has a portion to be pressed by being pressed. Moves,
A sensor whose physical characteristic value changes thereby, a sensor pressing portion, and an elastic member having a biasing force in a direction in which the sensor pressing portion moves away from the sensor are provided. By combining the two housings, a hole through which the seat belt is inserted in the front-rear direction between these housings is formed, and the seat belt passes through the hole on one side and is opposed to the sensor of the elastic member. A seat belt tension detecting device, wherein the seat belt tension detecting device is structured so as to be in contact with one side and to be inserted through the hole on the other side. 2. The seat belt tension detecting device according to claim 1, wherein the elastic member is within an elastically deformable range when the seat belt inserted through the hole becomes linear. The position of the hole, the sensor pressing portion, and the pressed portion of the sensor are determined so that the pressed portion of the sensor is within a movable range.