JPH0327005Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a webbing tension detection device that is used in a seat belt device for protecting an occupant in a vehicle emergency and detects webbing tension for restraining an occupant.

[Prior Art] As a webbing tension detector, the outer end of a mainspring spring whose inner end is locked to a webbing take-up shaft is fixed to a worm foil, and a worm that is supported so as to be slidable in the axial direction is connected to the worm. Engage with the foil,
A coil spring is arranged to balance the force that the worm receives from the worm wheel, and a striker that moves together with the worm operates a fixed limit switch to detect the axial position of the worm and detect the webbing tension. There is.

[Problems to be Solved by the Invention] However, in such a webbing tension detection device, the striker vibrates minutely due to fluctuations in the webbing tension due to vehicle vibration, and the limit switch chatters. For this reason, it has been necessary to provide a chattering removal circuit in the webbing tension control circuit to which the signal from the limit switch is input, or to remove the chattering by reading the input value many times using software. As a result, control circuits and microcomputer programs have become more complex.

[Means for Solving the Problems] The webbing tension detection device according to the present invention includes a worm that is pivotally supported to be slidable in the direction along the axis, and an elastic body that biases the worm in the direction along the axis. an actuating piece that moves integrally with the worm in a direction along the axis of the worm; a striker that loosely fits into a part of the actuating piece; It is characterized by having a guide that is supported in a loosely fitted state with a part of the actuating piece to prevent minute vibrations of the actuating piece from propagating to the striker, and a tension detection switch that is activated by movement of the striker.

[Operation] Therefore, when the webbing tension is transmitted to the worm through the worm foil, the worm moves in its axial direction and balances with the elastic body. This movement causes the actuating piece to move, and the striker, which is loosely fitted to a portion of the actuating piece, moves along the guide, and the striker actuates the tension detection switch. The webbing tension can be detected by the signal from this tension detection switch.

When the occupant vibrates due to vehicle vibration and the webbing tension fluctuates, the worm and actuating piece vibrate minutely in the axial direction of the worm. However, since the striker is supported by the guide in a loosely fitted state with a part of the actuating piece, the striker does not undergo minute vibrations. Therefore, the output of the tension detection switch does not chattering.

[Embodiment] FIGS. 1 and 2 show a webbing retractor 10 to which a webbing tension detection device according to a first embodiment of the present invention is applied. In this webbing retractor 10, a frame 12 is fixed to a vehicle body 16 with mounting bolts 14.

From both sides of the frame 12, a pair of leg plates 18,
20 are extended parallel to each other. Both end portions of a winding shaft 22 are pivotally supported on these leg plates 18 and 20, and one end of an occupant restraining webbing 24 is locked to the center of the winding shaft 22, and is wound in layers. It is being

The other end of this webbing 24 is the tongue plate 2.
5 is attached and is engageable with a buckling device 26 as shown in FIG. This buckle device 26 is attached to other parts of the vehicle body, and the middle portion of the webbing 24 is used for attachment by an occupant.

An inertia lock mechanism 27 is attached to the outside of the leg portion 20 between it and the winding shaft 22. This inertia lock mechanism 27 has a generally used structure, and it is
Detects the pull-out acceleration of the winding shaft 22 in case of vehicle emergency.
The rotation of the webbing drawer is suddenly stopped.

A base plate 28 is attached to the outside of the leg plate 18, and a screw 3 is attached to this base plate 28.
A worm wheel 34 is pivotally supported by the shaft support plate 32 and the leg plate 18, which are attached at 0. The outer end of the mainspring spring 36 is fixed to the inside of the worm wheel 34, and the inner end of the mainspring spring 36 is fixed to the winding shaft 22. Therefore, the mainspring spring 36 generates a biasing force against the worm wheel 34 to rotate the winding shaft 22 in the direction in which the webbing 24 is wound up.

A pinion 38 coaxially protrudes from the worm wheel 34 and meshes with a pinion 42 that is pivotally supported by a pin 40 that protrudes from the shaft support plate 32. This pinion 42 meshes with an internal gear 44 that is pivotally supported on the shaft support plate 32. As a result, the internal gear 4
4 is adapted to transmit the rotation of the winding shaft 22 at a reduced speed, and a striker 46 protruding from a part of the internal gear 44 corresponds to a limit switch 48 attached to the shaft support plate 32. The limit switch 48 is turned off when the occupant releases the webbing 24 and the maximum amount of the webbing 24 is wound onto the take-up shaft 22.
When the striker 46 is pulled out, the striker 46 is separated and turned on.

A worm 50 is engaged with the outer periphery of the worm wheel 34, and the worm 50 is attached to a worm shaft 52 as shown in FIG. To explain this in detail, the worm shaft 52 has a rectangular portion 52A through which the worm 50 penetrates.
It is inserted into a rectangular hole 50A formed in the axial center of the worm 50. Therefore, the worm 50 rotates together with the worm shaft 52, but is slidable in the axial direction of the worm shaft 52.

The wormshaft 52 has brackets 5 at both ends.
4 and 56 to the base plate 28, and the actuating piece 58 is pivotally supported to a circular portion formed adjacent to the rectangular portion 52A. This actuating piece 5
8, the penetrating portion of the worm shaft 52 is circular, and the actuating piece 58 can be rotated relative to the worm shaft 52 and also movable in the axial direction. This actuating piece 58 comes into contact with the side surface of the base plate 28 and is prevented from rotating, so that the worm shaft 52
It is movable in the axial direction. The actuating piece 58 is biased toward the worm 50 by a compression coil spring 60 interposed between the actuating piece 58 and the bracket 54, and is brought into contact with one end of the worm 50 in the axial direction.

A projection 58A is provided on the side surface of the actuation piece 58, and is loosely fitted into a recess 61A cut out in the striker 61. A groove 61B parallel to the base plate 28 is formed on both side surfaces of the striker 61, and a plate-shaped fitting portion 61C is formed on the surface on the base plate 28 side. On the other hand, a guide 63 is formed by bending the upright pieces 28A and 28B provided on the base plate 28 in a direction toward each other. This guide 63 has a C-shaped cross section and its longitudinal direction is parallel to the axial direction of the wormshaft 52. A fitting portion 61C of the striker 61 is fitted into the groove 63A of the guide 63 and is movable in the longitudinal direction of the guide 63.

Therefore, when the actuating piece 58 moves in the axial direction of the wormshaft 52, the striker 61 also moves together. However, the protrusion 58A
is loosely fitted into the recess 61A, so that even if the protrusion 58A slightly vibrates in the axial direction of the shaft 52, the striker 61C does not move.

As shown in FIG. 4, the actuating piece 58 receives the tension of the webbing 24 via the worm wheel 34, and when the tension of the webbing 24 is weak, the actuating piece 58 receives the worm 50 due to the biasing force of the compression coil spring 60. It is pressed against the bracket 56. In this state, as shown in FIG. 4A, the striker 61 turns on only 64 of the tension detection switches 62 and 64 attached to the base plate 28.

Further, when the tension of the webbing 24 is medium, the striker 61, which receives the webbing tension via the worm wheel 34 and the operating piece 61, is arranged so that both the tension detection switches 62 and 64 are turned on, as shown in FIG. 4B. Further, when the tension of the webbing 24 is strong, the compression coil spring 60 is compressed to the maximum amount as shown in FIG. 4C, and only the tension detection switch 62 is turned on.

A small gear 66 is fixed to an end 65 of the wormshaft 52 projecting from the bracket 56, and meshes with a large gear 68 via an intermediate gear 67. This large gear 68 is fixed to the output shaft of a motor 70, and the motor 70 is attached to the base plate 28.

FIG. 5 shows a control circuit diagram of this embodiment, in which a microcomputer 72 controls the limit switch 48 and the tension detection switches 62, 6.
4 outputs are inverters 48N, 62N,
64N, and the output of a buckle switch 74, which is disposed in the buckle device 26 and can detect the insertion state of the tongue plate 25 as shown in FIG. 2, is also input via the inverter 74. .

The power supply for the microcomputer 72 uses a DC voltage of 12V (B shown in FIG. 5) supplied from a DC voltage power supply (not shown), which is stepped down to 5V by a regulator 76. Further, this 12V is stepped down to 8V by a regulator 78, and constitutes a low voltage drive power source for the motor 70.

The drive voltage of the motor 70 is supplied by the relay coil 80 which is excited from the microcomputer 72 via the inverter 80N, and the C contact 82 is actuated.
It can be switched from 12V to 8V.
Further, the motor 70 is operated by a microcomputer 72.
The C contacts 88, 90 are actuated by relay coils 84, 86 which are excited via inverters 84N, 86N, respectively, to rotate forward or reverse. That is, when only the relay coil 84 is energized, it rotates in the normal direction, and when only the relay coil 86 is energized, it rotates in the reverse direction.

Next, the operation of this embodiment will be explained according to the flowchart shown in FIG. 6, which corresponds to the program stored in the microcomputer 72. Note that a part number of 100 or more means a step.
200 is simply abbreviated as 200.

First, we will explain what happens while wearing the webbing. While the webbing is being attached, the buckle switch 74 is on (100), and the relay coil 80 is excited to set the voltage applied to the motor 70 to 8V (102). Next, the buckle flag B/F is set (104) and the timer is cleared (106). Next, control the webbing tension so that it is inside. That is, when only the tension detection switch 62 is on and the webbing tension is strong, the relay coil 84 is energized and the motor 70 is rotated in the direction of arrow A in FIG. 1 (112). As a result, the worm wheel rotates in the A' direction, the mainspring spring 36 is loosened, and the webbing tension is weakened. The above steps 100 to 112 are repeated, and if it is read at 108 that both tension detection switches 62 and 64 are on, the relay coil 84 is demagnetized and the motor 70 is stopped (114). Thereby, even if the webbing tension is strong, it is maintained in the middle state. Therefore, the occupant will not be unnecessarily tightened, and the occupant will not feel uncomfortable.

If only the tension detection switch 64 is on at 108, that is, if the webbing tension is weak, the relay coil 86 is energized and the motor 70 is rotated in the opposite direction (116). As a result, the worm wheel rotates in the direction opposite to the direction of arrow A', tightening the mainspring spring 36 and increasing the webbing tension. Repeat the above steps 100 to 110 and 116, and at 108, the tension detection switches 62 and 6
If you read that both 4 are on,
The relay coil 86 is demagnetized and the motor 70 is stopped (114). Thereby, even if the webbing tension is low, it is maintained in the middle state. Therefore, the webbing is not loosened more than necessary, and the vehicle can respond to emergencies.

In the above processing, the voltage applied to the motor 70 is a low voltage of 8V, so the power of the motor 70 is relatively low, and the abnormal noise caused by the rotation of the motor 70 is low. Therefore, the occupants will not feel uncomfortable.

Next, the case of releasing the webbing attachment will be explained. When the tongue plate 25 is disengaged from the buckle device 26, the buckle switch 74 turns off (100), demagnetizes the relay coil 80, and demagnetizes the motor 7.
Set the applied voltage of 0 to 12V. (200). Initially, the striker 46 turns on the limit switch 48, and it is determined that webbing winding is complete (202), and the process proceeds to 204. Initially, the buckle flag B/F is set to 1 at 104 (204), and the webbing tension is controlled in the same manner as described above to make it strong (206, 208, 210). In this case, since the webbing 24 is wound around the take-up shaft 22, the biasing force of the mainspring spring 36 becomes weaker. Therefore, by controlling the tension strength, the worm wheel 34 rotates in the direction opposite to the direction of arrow A' in FIG.
The striker 46 is separated from the limit switch 48 by rotating in the direction A'. limit switch 48
When this turns off, it is determined at 202 that webbing winding is complete, and then the buckle flag B/F is reset (212), and when it is 1, the 10 second elapsed flag 1 indicates that 10 seconds have passed since the webbing was pulled out.
0S/F is reset (214). Next, the steps 106 and below are performed, and the webbing tension is controlled to be medium as described above, and the motor 70 is turned off in a state where the webbing tension is medium.

Therefore, during and after winding the webbing, the voltage applied to the motor 70 is a high voltage of 12V, so the power of the motor 70 is relatively strong, and the webbing 24 is quickly wound around the winding shaft 22.
After winding, the webbing tension is controlled to be within the range immediately. During and after this winding, which occurs after the webbing is attached, is a short period of time, so even if the abnormal noise accompanying the rotation of the motor 70 is loud, it does not particularly cause discomfort to the occupant. Moreover, since the webbing tension is medium after winding up, the webbing 24 will not be pulled out inadvertently.

Next, the process from pulling out the webbing to putting it on will be explained. When the webbing 24 is pulled out a little, the webbing tension tends to become strong, but as described above, the webbing tension is controlled to be medium. Therefore, the occupant can easily pull out the webbing 24. By the above control, the motor 70 rotates in the direction of arrow A, and the internal gear 44 rotates in the direction opposite to the direction of arrow A'. When the webbing 24 is pulled out by a predetermined amount (a small amount), the striker 46 turns on the limit switch 48, and the processing moves from 202 to 204.
Since the buckle flag B/F has been reset at 212, the process advances to 300. 214, 10 seconds elapsed flag 10S/
Since F has been reset, motor 70 is stopped (302). Initially, since 10 seconds have not elapsed on the timer (304), the timer is counted (306), and then the above processes 100, 200, 204, 300, 302, 304, and 306 are repeated. If it is determined in 304 that the timer has elapsed for 10 seconds, that is, if the webbing is not attached during these 10 seconds and the buckle switch remains off (100), the 10 seconds elapsed flag S/F is set in 308.
is set. Next, the process proceeds to 100, 200, 204, and 300, and since 10S/F is set at 300, the webbing tension is controlled to be strong by the processing in steps 206 to 210.

Therefore, if the webbing is not attached even after 10 seconds have passed after the webbing is pulled out, the same process as that after the webbing is released is performed. That is, the tension of the webbing 24 is increased and the webbing 24 is wound onto the take-up shaft 22, and when this winding is completed, the process progresses from 202 to 212, and the webbing tension is controlled to a medium level and the motor 70 is stopped.

Normally, the webbing 24 is attached within 10 seconds after the webbing is pulled out, the buckle switch 74 is turned on, and the above-mentioned processing during webbing attachment is performed.

In addition, contrary to the above embodiment, a structure may be adopted in which a recess is provided in the actuation piece 58 and a protrusion provided on the striker 61 is loosely fitted therein.

[Effect of the invention] In the webbing tension detection device according to the invention, a striker is interposed between the tension detection switch and an actuation piece that moves integrally with the worm in the axial direction of the worm, and this striker is a part of the actuation piece. It has a simple configuration in which it is supported by a guide in a loosely fitted state.
Even if the actuating piece vibrates minutely in the axial direction of the worm due to vehicle vibration, the striker does not vibrate minutely, and has the excellent effect of eliminating chattering in the signal from the tension detection switch.

[Brief explanation of the drawing]

1 is a partially exploded perspective view of a webbing retractor to which a webbing tension detection device according to a first embodiment of the present invention is applied; FIG. 2 is a side view of FIG. 1;
The figure is an exploded perspective view of the worm and its related parts.
The figure is an explanatory diagram of the operation of the webbing tension detector, FIG. 5 is a control circuit diagram, and FIG. 6 is a flowchart showing the control flow of the microcomputer. 50...Worm, 52...Wormshaft, 5
8... Actuation piece, 58A... Protrusion, 60... Compression coil spring, 61... Striker, 61A... Recess, 6
1B...groove, 61C...fitting part, 62, 64...tension detection switch, 63...guide.

Claims (1)

[Scope of utility model registration request] A worm supported slidably in the direction along the axis, an elastic body that biases the worm in the direction along the axis, and an actuating piece that moves integrally with the worm in the direction along the axis of the worm. , a striker that loosely fits into a part of the actuating piece, guides the striker in a direction along the axis of the worm, and supports the striker in a loosely fitted state with a part of the actuating piece, so that minute vibrations of the actuating piece are propagated to the striker. A guide to prevent
A webbing tension detection device comprising: a tension detection switch activated by movement of a striker.