JPH0245098Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Field of Application of the Invention] The present invention relates to a webbing retractor for retracting occupant restraint webbing used in a seat belt device for protecting occupants in vehicle emergencies, and for reducing webbing tension generated by a retracting shaft. The present invention relates to a webbing take-up device that is designed to take up a webbing. [Background Art] In a webbing retractor used in a seat belt device, one end of the webbing for restraining an occupant is attached to a retracting shaft, and the retracting shaft is rotated by the biasing force of a mainspring spring to rewind the webbing in layers. It's getting old. The biasing force of this mainspring is set to a predetermined value or more in order to ensure that the webbing is retracted after the occupant releases the webbing device, and when the occupant attaches the webbing, it is necessary to pull out the webbing with a relatively large force. After wearing the webbing, passengers feel a relatively large resistance while driving or when moving inside the vehicle. For this reason, a winding device has been proposed in the past that eliminates the mainspring spring, transmits the driving force of a motor to a winding shaft, and rotates the winding shaft with this motor driving force to wind up the webbing. However, the control of this retractor is complicated, and when the webbing is retracted by a motor to eliminate the slack (gap) that occurs between the occupant and the webbing while the occupant is wearing the webbing, it may cause damage to the occupant, especially the occupant. This may cause a small shock to the shoulder area of the person, causing discomfort. Furthermore, with this conventional webbing retractor, if a failure occurs in the control system, electrical system, motor body, etc., it is only possible to pull out the webbing, which increases the slack and makes it impossible for the occupant to continue wearing the webbing. Something happened. In order to solve this problem, the same applicant connected the winding shaft to the worm wheel via an elastic body, installed a worm gear that engaged with the worm wheel, and a motor for driving the worm gear, and used the rotating force of the motor to connect the winding shaft to the worm wheel. The webbing retractor reduces the webbing tension applied to the occupants by adjusting the webbing retracting force, reducing the feeling of pressure on the occupants, and the combination of the worm wheel and worm gear ensures that the webbing remains attached even in the event of an electrical system failure. An application was filed for the device (Utility Application No. 58-75129 (see Utility Model Application No. 59-179148)). However, the invention of this application can only switch the tension of the webbing between strong and weak (or zero), and requires a complicated control circuit to always obtain a suitable webbing tension. [Purpose of the invention] The present invention has been made in view of the above circumstances, and its purpose is to provide a webbing take-up device that has a simple structure and can always obtain a suitable webbing tension. [Structure of the invention] The webbing retractor according to the invention includes a take-up shaft for winding up one end of the occupant restraint webbing, an elastic body having one end connected to the take-up shaft, and the other end of the elastic body being connected to the take-up shaft. a worm wheel that is attached to adjust the webbing winding force by the elastic body; a worm gear that engages with the worm wheel and is supported so as to be movable in the axial direction by a predetermined amount under a predetermined load of the elastic body; and a worm gear that rotates the worm gear. a detection means for detecting at least predetermined both end limits of the axial movement range of the worm gear; control means that rotates the motor in a direction that weakens the force, and also rotates the motor in a direction that increases the urging force of the elastic body via the worm gear and the worm wheel when the worm gear moves to the other end of the movement range according to the detection means; It is characterized by having the following. [Operation of the invention] According to the invention, when the webbing is pulled out from the take-up shaft to attach the webbing, the take-up shaft and the worm wheel are rotated relative to each other, so that the attachment positions of both ends of the elastic body change. Then, a load is applied to the elastic body. Therefore, the worm wheel is urged to rotate in the same direction as the take-up shaft, and this rotation causes the worm gear to move in the axial direction. When the worm gear is axially moved and reaches one end of the movement range, this is detected by the detection means. As a result of this detection, the worm gear is rotated by the drive of the motor, this rotational force is transmitted to the worm wheel, and the worm wheel is rotated in the same direction as the rotation of the take-up shaft. This weakens the biasing force of the elastic body, reduces the load when pulling out the webbing, and allows the webbing to be pulled out easily. Note that when the above-mentioned load becomes smaller, the worm gear is axially moved in the opposite direction to be located in the middle of the above-mentioned movement range, and the drive of the motor is stopped. Further, immediately after the webbing is worn, the webbing is pulled out excessively, which may cause slack. In such a case, when the worm gear axially moves to the other end of the movement range and this is detected by the detection means, the motor is rotated in a direction that increases the biasing force of the elastic body, and the webbing can be wound more quickly. . Furthermore, when the slack is removed, the worm gear reaches the middle position of its movement range and the motor drive is stopped, so the biasing force of the elastic body becomes weaker, and there is almost no pressure on the occupants, and the It is possible to maintain a comfortable wearing condition. In this way, by detecting both ends of the movement range of the worm gear, the biasing force of the elastic body can be easily changed depending on the pulled-out state of the webbing, so that the feeling of wearing the webbing can be improved. [Embodiment of the invention] Figs. 1 and 2 show a webbing take-up device 10 according to a first embodiment of the invention. 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. ing. The other end (not shown) of the webbing 24 is attached to other parts of the vehicle body via a tongue plate and a buckle device with which the tongue plate engages, and the middle portion of the webbing 24 serves as a mounting portion for the occupant. An inertia lock mechanism 26 is attached to the outside of the leg plate 18 between it and the winding shaft 22. This inertia lock mechanism 26 has a commonly used structure, and is designed to detect vehicle body acceleration or webbing 24 pull-out acceleration and abruptly stop the webbing pull-out rotation of the take-up shaft 22 in the event of a vehicle emergency. A plate-like holder 28 is attached to a screw 30 on the outside of the leg plate 18.
It is fixed in place. A small-diameter portion 32 formed at the end of the winding shaft 22 passes through this plate-like holder 28, and a cylindrical spring case 34 is pivotally supported at the bottom plate portion of the tip. After the spring case 34 is covered with a cover 35, a stopper 36 press-fitted into the tip of the small diameter portion 32 prevents the spring case 34 from being pulled out from the small diameter portion 32. This stopper 36
is fixed to the tip of the small diameter portion 32 by a screw 37. Further, the spring case 34 has a worm wheel 38 engraved on its outer periphery, and the outer end of a mainspring spring 40 is locked on its inner periphery. This mainspring spring 40 is arranged coaxially with the small diameter portion 32, and its inner end is locked to the small diameter portion 32. Therefore, when the mainspring spring 40 is rotated in the direction d in FIG. 2, the biasing force increases and applies a force in the webbing winding direction to the winding shaft 22, and conversely, when the mainspring spring 40 is rotated in the direction D in FIG. The winding force is reduced. Worm gear 4 meshing with worm wheel 38
2 is pivotally supported by a bracket 48 of the holder 28 via a rectangular shaft portion 46 of a shaft 44, as shown in FIG. Therefore, the worm gear 42 rotates together with the shaft 44, but can move relative to the shaft 44 in the axial direction. However, since one end of the worm gear 42 is in contact with the bracket 48, the worm gear 42 can only move in one direction (diagonally downward in the figure) from the state shown in FIG. The actuator 5 is located at the other end of the worm gear 42.
0 is arranged and movably provided along the shaft 44. Further, a spacer 49 is fitted into a portion of the shaft 44 so as to be movable in the axial direction, and a small compression coil spring 51 is interposed between the spacer 49 and the actuator 50. Further, a large compression coil spring 52 is also interposed between the spacer 49 and the bracket 48. Therefore, the actuator 50 is pressed in the axial direction (diagonally upward in FIG. 2) together with the worm gear 42 by the urging force of both compression coil springs 51 and 52. Corresponding to the lower part of the actuator 50 are limit switches 56 and 58 fixed to the plate-like holder 28 with screws 54, as shown in FIG.
Each limit switch 56, 58 is actuated by the axial movement of the actuator 50. In FIG. 2, both are off, in FIG. 4, the limit switch 56 is on and limit switch 58 is off, and in FIG. 5, both limit switches 56, 58 are on. It is in a state of A bevel gear 60 is connected to the end of the shaft 44 projecting from the bracket 48, and the bevel gear 60 meshes with the bevel gear 62 in a perpendicular manner. Bevel gear 62
is fixed to an output shaft 66 of a motor 64 fixed to the leg plate 18 and the plate-shaped holder 28. FIG. 6 shows a circuit diagram for controlling the motor 64, and a microcomputer 68 is used in this control circuit. Signals from the aforementioned limit switches 56, 58 and buckle switch 70 are input to the input side of the microcomputer 68.
The buckle switch 70 is turned on when the tongue plate (not shown) attached to the webbing 24 shown in FIG. It has a normally closed contact that turns off when the webbing is released. As can be seen from FIG. 2, when tension is applied to the webbing 24, this tension moves the worm gear 42 diagonally downward (in the direction of compressing the compression coil springs 51, 52) via the worm wheel 38. Therefore, the magnitude of the webbing tension can be determined depending on the on/off state of each limit switch 56, 58. In this embodiment, FIGS.
The tension is detected by the microcomputer 68 over the three stages shown in FIGS. In the following description, the webbing tension state in FIG. 2 will be referred to as "weak" or "0," FIG. 4 will be referred to as "medium," and FIG. 5 will be referred to as "strong." The microcomputer 68 is connected to the webbing 24
When the limit switches 56 and 58 are both on, that is, in the "strong" state while the buckle switch 70 is being installed (the buckle switch 70 is on), the switching element 72 is actuated and the relay 74 is energized. This relay 78 turns on the switch 76 with an excitation force, and drives the motor 64 in the direction in which the webbing 24 is unwound. When limit switches 56 and 58 are both off, ie, in the "weak" state, switching element 78 is activated, relay 80 is energized, and switch 82 is turned on. As a result, a current in the opposite direction to that described above flows through the motor 64, and the motor 64 is driven to wind up the webbing 24. Furthermore, the motor 64 is not driven when only the limit switch 56 is on, that is, in the "in" state. That is, the microcomputer 68 always maintains the tension of the webbing 24 in the "medium" state when the webbing is attached. The webbing tension in the "medium" state is set to a value that does not generate slack in the webbing 24 and does not give the occupant a feeling of pressure. In addition, "weak" means that the webbing tension is almost 0,
"Strong" is set to a tension that is approximately the same level as the winding force of the mainspring. The webbing retractor 10 of this embodiment configured as described above operates in the following order. Before the occupant wears the webbing 24, the webbing 24 is fully wound. In addition, the worm gear 42 is the second
Since the limit switches 56 and 58 are both in the position shown in the figure and off, the tension of the webbing 24 is in a "weak" state. Therefore, the webbing 24 is in a state where it can be easily pulled out. Here, when the occupant pulls out the webbing 24 from the take-up shaft 22, the inner end of the mainspring spring 40 rotates clockwise in FIG. 2, thereby increasing its biasing force. Due to this increase in biasing force, the spring case 34 receives a rotational force in the clockwise direction, so the worm gear 42
A force is generated toward the lower left of the figure. This force moves actuator 50 against the urging force of compression coil springs 51 and 52, turning on both limit switches 56 and 58 as shown in FIG. When the occupant engages the tongue plate of the pulled-out webbing 24 with the buckle device, the buckle switch 70 is turned on. This means that the webbing tension is "strong" as described above, so the microcomputer 68 (see FIG. 6) sends a signal to the switching element 72, drives the motor 64, and moves the spring case 34 in the webbing unwinding direction. Rotate to Therefore, the outer end of the mainspring spring 40 also rotates in the same direction, and the biasing force of the mainspring spring 40 becomes weaker. That is, although the biasing force of the mainspring spring 40 tends to increase as the webbing 24 is pulled out, the mainspring spring 40 is rotated in a direction to cancel this biasing force by driving the motor 64. This motor drive continues until the webbing tension reaches the "medium" state. If the above-mentioned operation is shown in the flowchart of FIG. 7, it is determined in step 84 whether the buckle switch 70 is on or off, and if it is on, the buckle switch 70 is turned on in step 86.
If it is off, the process returns to step 84. In step 86, the motor 64 is turned on to rotate the spring case 34 in the webbing unwinding direction, and the process proceeds to step 88. In step 88, it is determined whether or not the webbing tension has been reduced to "medium". If it has been reduced, the process proceeds to step 90 and the motor 64 is stopped; if not, the above-described operation is repeated. While the webbing 24 is being attached, step 92 is always performed.
In step 94, the strength of the webbing tension is determined. If slack occurs in the webbing 24 while the occupant is wearing the webbing, the tension becomes 0 and the actuator 5
0 is in the state shown in FIG. 2 due to the urging force of both compression coil springs 51 and 52. Therefore, both limit switches 56 and 58 are turned off, and in step 96 the motor 64 is operated to wind up the webbing 24, and in step 98 it is determined whether the webbing tension has been increased to "medium". . If the tension is "medium", the motor 6 is turned on at step 100.
4 is stopped and the above-mentioned operation is repeated if it has not reached "middle" yet. After the motor 64 has stopped, the process returns to step 92. When the occupant moves toward the front of the seat, the worm wheel 38 also rotates clockwise to move the worm gear 42 in the axial direction, as shown in FIG.
That is, since the tension of the webbing 24 becomes "strong", the actuator 50 turns on both limit switches 56 and 58, and as a result, the motor 64 unwinds the webbing 24 in step 102. Next, in step 104, it is determined whether the webbing tension has been reduced to "medium".
If it is "medium", the motor 64 is stopped at step 106, and if not, the above-mentioned operation is repeated.
After the motor 64 is stopped, the process returns to step 92 again. In this manner, while the webbing is being worn, the webbing tension is always controlled to be in the "medium" state.
In the "medium" state, the actuator 50 and both limit switches 56, 58 are in the position shown in FIG. 4, and only the small compression coil spring 51 is compressed. Next, in step 108, the buckle switch 70 is
is determined to be on or off. That is, if the webbing continues to be attached, the process returns to step 92, and if the tongue plate is removed from the buckle device and the webbing is released, the process proceeds to step 110. In step 110, a timer (not shown) operates the motor 64 for 10 seconds, and the webbing 24 is wound onto the take-up shaft 22. Also, mainspring 4
Since a winding force of 0 also acts on the webbing 24, this winding operation is performed smoothly. The webbing tension at this point is set to be "strong." When the motor 64 stops, it is determined in step 112 whether the webbing tension is "medium" or not.
If it is "medium", the process advances to step 114; otherwise, the above-mentioned operation is repeated. In step 114, the motor 64 is connected to the spring case 3.
4 in the drawing direction to reduce the tension on the webbing 24, and proceed to step 116. In step 116, it is determined whether the webbing tension has been reduced to "weak". If it is "weak", the process proceeds to step 118, and if it is insufficient, the above-described operation is repeated. At step 118, the motor 64 is stopped, and the take-up device is returned to its initial state, that is, a state in which the webbing 24 can be easily pulled out. Each switch 56, 5 while wearing webbing
The relationship between the motor 64 and the motor 64 is as follows.

[Effect of idea]

As mentioned above, the webbing retractor of the present invention is equipped with a detection means that converts the webbing tension into the amount of axial movement of the worm gear, detects it in three or more stages, and controls the rotation of the motor accordingly. Therefore, it has the effect of ensuring a comfortable webbing tension while wearing the webbing with a simple structure.

[Brief explanation of drawings]

Fig. 1 is a partial vertical cross-sectional view showing a first embodiment of the webbing retractor according to the present invention, Fig. 2 is a left side view of Fig. 1, and Fig. 3 is an enlarged cross-section along the line shown in Fig. 2. Figures 4 and 5 show the second
6 is a control circuit diagram of the first embodiment, FIG. 7 is a flowchart of the first embodiment, and FIG. 8 is a left side view showing the second embodiment of the present invention. 9
The figure is a left side view showing a third embodiment of the present invention. 10... Webbing winding device, 22... Winding shaft, 24... Webbing, 34... Spring case,
38...Worm wheel, 40...Spring spring, 42...Worm gear, 44...Shaft,
50... Actuator, 51, 52, 128...
...Compression coil spring, 56, 58...Limit switch, 64...Motor, 68...Microcomputer.

Claims (1)

[Scope of utility model registration request] A take-up shaft for winding one end of occupant restraint webbing, an elastic body having one end connected to the take-up shaft, and a worm wheel to which the other end of the elastic body is attached to adjust the webbing winding force of the elastic body. a worm gear that engages with the worm wheel and is supported so as to be movable in the axial direction by a predetermined amount under a predetermined load of the elastic body; a motor that rotates the worm gear; and at least predetermined both ends of the axial movement range of the worm gear. a detection means for detecting a limit; and a detection means for rotating the motor in a direction to weaken the biasing force of the elastic body via the worm gear and the worm wheel when the worm gear moves to one end of the movement range; A webbing take-up device comprising: control means for rotating a motor in a direction that increases the biasing force of the elastic body via the worm gear and worm wheel when the webbing take-up device moves to the other end of its movement range.