JPH047018Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a webbing tension control device used in a webbing retractor of a seat belt device for protecting vehicle occupants.

[Background technology]

A webbing take-up device is generally capable of fully winding the webbing by the biasing force of a mainspring spring. However, it is not easy to optimize the webbing tension that is applied when the occupant wears the webbing, which may give the occupant a feeling of pressure. Therefore, a device has been devised in which a webbing tension sensor is provided in a webbing take-up device to detect and control the webbing tension.

However, the mechanical structure of the webbing tension control device is generally complex, and the accommodation space thereof is large.

[Purpose of invention]

In consideration of the above facts, the present invention has a simple structure that allows the accommodation space of the mechanical structure to be narrowed, and since it directly detects the biasing force of the mainspring, it is possible to adjust the biasing force to the desired force with high precision. Moreover, it is an object of the present invention to obtain a webbing tension control device that can set a plurality of biasing forces as necessary.

[Structure of the idea]

The webbing tension control device according to the present invention has an inner end locked to a take-up shaft for winding and accommodating the webbing, and an outer end locked to a casing that rotates around the take-up shaft. a mainspring spring that biases the webbing in the webbing winding rotation direction; an adjusting means that rotates the casing to adjust the biasing force of the mainspring spring; a cam plate that rotates around the take-up shaft in one direction by a torque applied in response to the rotational force; a biasing means that biases the cam plate in a direction opposite to the one direction; A position detecting means that includes a protrusion and a sensor disposed on the locus of movement of the protrusion and detects the rotational position of the cam plate; and a signal from the position detecting means to detect whether the webbing is being attached before being attached, being attached, or being unattached. and a control circuit that detects any state at the time and controls the adjusting means to adjust the biasing force in the webbing winding direction of the winding shaft by the mainspring spring to an appropriate value.

[Effect of invention]

According to the present invention, when the webbing is pulled out and the take-up shaft rotates, the cam plate rotates in one direction via the gear mechanism in response to this rotation.

Since this cam plate is biased by the biasing means in a direction opposite to the one direction in which it acts due to the rotation of the winding shaft, the biasing force of the biasing means becomes larger than the biasing force of the mainspring. At this time, the cam plate is rotated in a direction opposite to the one direction by the urging force of the urging means. Therefore, the cam plate can obtain a rotation amount that corresponds to the biasing force of the mainspring spring.

The rotational position of the cam plate is detected by the position detection means, and the control circuit controls the adjustment means based on the detection result to rotate the casing. This allows the biasing force of the mainspring to be changed.

In other words, the biasing force of the mainspring spring can be replaced with the rotational position of the cam plate and detected with high accuracy. Furthermore, since the cam plate rotates around the take-up shaft, the installation space can be reduced.

[Example of idea]

An embodiment of the webbing tension control device according to the present invention will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the webbing tension unit 10 is built into a case 12. This case 12 is screwed with screws 20 to a side wall 18 of a frame 16 on which a webbing take-up shaft 14 is mounted.

A small diameter shaft 22 is provided protruding from the end of the winding shaft 14, and the inner end of the mainspring spring 24 is locked to this. The outer end 26 of the mainspring spring is locked to the inner circumferential surface of a spring case spring case 28 as a casing. Winding shaft 1 of spring case 28
A cylindrical boss 30 is provided protruding from the end face of the fourth side. This boss 30 is pivotally supported in a hole 32 bored into the end face of the case 12. A shaft 34 is provided upright on the end surface of the spring case 28 opposite to the boss 30.

This shaft 34 is stepped and has a large diameter portion 36, a medium diameter portion 38, and a small diameter portion 40. This large diameter portion 36 is connected to the board 4 which is screwed onto the case 12.
It is pivotally supported in a hole 46 of a boss 44 provided at the center of the 2. The substrate 42 is parallel to the bottom surface of the case 12. A sun gear 48, which constitutes a part of the gear mechanism, is fitted into the medium diameter portion 38. A groove 50 is formed between the small diameter portion 40 and the medium diameter portion 38, and a retaining ring 52 is attached to the groove to secure the sun gear 4.
8 is prevented from moving in the axial direction. Small diameter part 40
supports a worm wheel 54 that constitutes a part of the adjustment means. The worm wheel 54 has a U-shaped longitudinal section, and the sun gear 48 is disposed in a recess 56 of the worm wheel 54 . An internal gear 58 is formed on the inner peripheral surface of the recess 56 . sun gear 48
A planetary gear 60, which together with the sun gear constitutes a gear mechanism, is interposed between the inner gear 58 and the inner gear 58.
The planetary gear 60 is pivotally supported by a rivet 64 to a cam plate 62 which is pivotally supported by the boss 44. Protrusions 66 and 68 are erected on the opposing surfaces of the cam plate 62 and the base plate 42, respectively, and the ends of a tension coil spring 70, which is a biasing means, are engaged with these protrusions. An arc-shaped hole 72 into which the protrusion 66 is inserted is bored in the substrate 42 . Further, on the substrate 42, protrusions 74, 7 as protrusions of the position detection means provided on the outer peripheral surface of the cam plate 62 are provided.
6 and 78 (see FIG. 3), limit switches 80 and 82 as sensors of position detection means are screwed in with screws 84.

The worm wheel 54 is connected to a motor 86 which together with the worm wheel 54 constitutes an adjusting means.
It meshes with a worm gear 88 fitted onto the rotating shaft of the worm gear 88. The motor 86 is fixed to the bottom surface of the case 12 with screws 92 via a bracket 90. A lid 94 is screwed onto the case 12 with screws 96 to close the opening.

Next, the operation of the mechanical components of the first embodiment configured as described above will be explained.

When the occupant pulls out the webbing (not shown), the take-up shaft 14 rotates against the elastic force of the mainspring spring 24, and the elastic force of the mainspring spring 24 gradually increases. As a result, the spring case 28 becomes the mainspring spring 2.
4 receives torque from the outer end 26 of the winding shaft 14, and rotates in the same direction as the winding shaft 14, and the sun gear 48 rotates accordingly. Then, the planetary gear 60 revolves around the sun gear 48 while rotating. Along with this revolution, the cam plate 62 rotates around the boss 44,
The tension coil spring 70 is gradually tensioned.
In this way, the cam plate 62 stops when the torque received from the tension coil spring 70 becomes equal to the torque received from the rivet 64, and the rotation of the gears 48, 60 and the spring case 28 accordingly stops. In this case, the worm wheel 54 remains stationary because it meshes with the worm gear 88.

When the motor 86 is rotated, the worm gear 8
8. The spring case 28 rotates via the worm wheel 54, the planetary gear 60, the sun gear 48, and the shaft 34 in order, and the elastic force of the mainspring spring 24 increases or decreases, resulting in a new balanced state.

In this embodiment, the recess 56 of the worm wheel 54
Because the gears 48, 60 are arranged inward and the cam plate 62 is located parallel to and close to the worm wheel 54, the webbing tension unit 10 can be stored in a narrow space.

Next, referring to FIG. 3, the relationship between the tension applied to the webbing and the on/off state of the limit switches 80 and 82 will be explained. In the following, for example, the case where limit switch 80 is on and limit switch 82 is off is expressed as (1, 0).

When the elastic force of the main spring 24 is weak, it becomes (1, 0), and as the elastic force of the main spring 24 becomes even stronger, the cam plate 62 rotates counterclockwise in FIG. 0,0),
(0,1), (1,1). Therefore, the strength of the tension applied to the webbing can be known by the on/off combination of the limit switches 80 and 82. In the explanation of the flowchart described later, when (1,0), T=1, (0,0)
When T=2, when (0, 1), T=3, (1,
In case 1), explanation will be made assuming that T=4.

Next, the control circuit for the motor 86 will be explained with reference to FIG.

The motor 86 is controlled by a microcomputer 100 (including an interface) as the main part of the control circuit. In other words, the a contacts of limit switches 80 and 82
On/off signals from LS1, LS2 and the a-contact BSW (buckle switch) of a limit switch built into a buckle device (not shown) are input to the microcomputer 100. Further, the microcomputer 100 is adapted to drive relays R1 and R2 via power transistors 102 and 104. Lead wires of a motor 86 are connected to common terminals 104 and 106 of c-contacts of relays R1 and R2. The operation of the motor 86 stops when both relays R1 and R2 are off (the state shown in FIG. 4), and when only relay R1 is on, it rotates in the normal direction (in the direction of increasing the webbing tension). When only relay R2 is on, the rotation is reversed (rotated in the direction of decreasing the webbing tension).

Next, the software of the microcomputer 100 will be explained according to the flowcharts shown in FIGS.

In this flowchart, when the occupant puts on the webbing, the webbing tension T is controlled to be 2, when the occupant releases the webbing, the webbing tension T is controlled to become T=4, and then after a certain period of time, T= It is now controlled so that it becomes 2. This will be explained in detail below.

In step 200, flag F is reset. This flag is used to determine whether before the webbing is attached or after the buckle is released when the buckle switch BSW is off. Next, in step 202, the buckle switch BSW
Read on/off of. Next, in step 204, the branch destination is determined by this on/off.
If BSW is off, the branch destination is determined in step 206 based on the value of flag F. F=
If it is 0, the webbing has not yet been attached, so the process returns to step 202.

If the BSW is on, that is, if the occupant wears webbing, flag F is set (step 210) and the value of X is set to 2 (step 212). This value of X is the webbing tension target value passed to the next processed motor control subroutine (step 214). As shown in FIG. 6, this subroutine reads the on/off status of the limit switches LSW1 and LSW2 in step 300, and then in step 302, the value of the webbing tension T determined from this on/off pair and the target given from the main routine are read. The value of X is compared and the branch destination is determined. T>X,
That is, when the current webbing tension is greater than the target value, the motor 86 is reversed to loosen the mainspring spring 24 (step 304). T<X
In this case, control is performed in the opposite manner to that described above (step 30).
6). If T=X, that is, the current webbing tension matches the target value, the motor 86
Turn off. In addition, the microcomputer 100
The output from the microcomputer 100 is latched, so that, for example, even if a normal rotation signal is further output while the motor 86 is rotating in the normal direction, the output from the microcomputer 100 will not change.

After completing the above processing, return to the main routine,
The process moves to step 202.

Next, in step 206, if F=1, that is, after the buckle has been released, the target value X of the webbing tension is set equal to 4 (step 216), and the motor is controlled (step 21).
8). Next, in step 220, the branch destination is determined depending on whether the webbing tension T has become equal to the target value 4. If T≠4, step 2
Return to 18. If T=4, in step 222, the process waits for 5 seconds. During this time, the webbing is wound around the winding shaft 14 with sufficient winding force. Next, in order to make it easier to unwind the webbing next time and to prevent the webbing from being unwound inadvertently, the target value X of the webbing tension is set equal to 2 (step 224), and the webbing tension T is set to this value. Match the target value (steps 226, 228). Next, if the target value is matched, the process returns to the first step 200 and the above process is repeated.

In this way, it is possible to set the webbing tension T to an appropriate value before wearing the webbing, while wearing the webbing, and when releasing the webbing, and it is possible to improve the usability of the seat belt device for the occupant.

[Effect of idea]

The webbing tension control device according to the present invention has a simple structure and can narrow the housing space for the mechanical structure, and also directly detects the biasing force of the mainspring spring, so it can adjust to the desired biasing force with high precision. Moreover, it has the excellent effect of being able to set a plurality of biasing forces as necessary.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of the mechanical configuration of an embodiment of the webbing tension control device according to the present invention;
Fig. 2 is a partial cross-sectional view of the unit shown in Fig. 1 when assembled, Fig. 3 is a simplified cross-sectional view taken along the - line in Fig. 2,
Figure 4 is the control circuit diagram of Figure 1, Figures 5 and 6 are the control circuit diagram of Figure 4.
This is a flowchart corresponding to a program stored in R0M of the microcomputer shown in the figure. 24... Mainspring spring, 54... Worm wheel (adjustment means), 62... Cam plate, 70
...Tension coil spring (biasing means), 74,
76, 78... protrusion (protrusion), 80, 82...
Limit switch (sensor), 86...motor (adjustment means).

Claims (1)

[Scope of utility model registration request] a mainspring whose inner end is locked to a take-up shaft that winds and accommodates the webbing, whose outer end is locked to a casing that rotates around the take-up shaft, and which urges the take-up shaft in the webbing winding rotation direction; a spring, an adjusting means for rotating the casing to adjust the biasing force of the mainspring spring, and a rotational speed of the winding shaft is reduced and the winding shaft is moved in one direction by a torque applied in accordance with the biasing force of the mainspring spring. a cam plate that rotates around the cam plate; a biasing means that biases the cam plate in a direction opposite to the one direction; a radial protrusion formed on the cam plate; a position detecting means for detecting the rotational position of the cam plate, and a position detecting means for detecting the rotational position of the cam plate; and an adjusting means for detecting any state of the webbing before, during, or when the webbing is not attached based on a signal from the position detecting means. a control circuit that controls the biasing force of the winding shaft in the webbing winding direction by the mainspring spring to an appropriate value.