GB2153203A

GB2153203A - Seat belt winding apparatus providing controlled tension

Info

Publication number: GB2153203A
Application number: GB8501257A
Authority: GB
Inventors: Noboru Tsuge; Masahiro Taguchi; Sotosi Kuwakado; Kazutaka Katoh
Original assignee: Nippon Soken Inc
Current assignee: Soken Inc
Priority date: 1984-01-28
Filing date: 1985-01-18
Publication date: 1985-08-21
Also published as: JPS60157943A; GB2153203B; CA1259394A; GB8501257D0; AU557370B2; DE3502779A1; AU3796385A

Abstract

A seat belt winding apparatus includes a winding mechanism having a buckle provided at a seat of a vehicle, a buckle sensor for detecting whether or not the buckle is coupled with a tongue plate fixed to a seat belt, a slack sensor for detecting slack in the seat belt by operation of the slip joint, and a motor for winding the seat belt. The seat belt winding apparatus also includes a control circuit which generates a control signal for controlling the seat belt winding mechanism in response to signals from the buckle and slack sensors. The control circuit includes a motor reverse rotation detecting element, a motor load detecting element, and motor driving element, so that the motor is driven when the reverse rotation thereof is detected.

Description

SPECIFICATION Seat belt winding apparatus BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat belt winding apparatus. More particularly, a seat belt winding apparatus according to the present invention is applied to a seat belt for protecting passengers in vehicles.

2. Description of the Related Art In conventional seat belt winding apparatuses, the seat belt is under continuous tension from a powerful spring, and a passenger wearing the seat belt is made uncomfortable by the pressure on the seat belt stemming from this tension. This tension also makes it difficult for the passenger to fasten the seat belt.

SUMMARY OF THE INVENTION The object of the present invention is to provide an improved seat belt winding apparatus which can detect, reverse rotation of a seat belt winding means in such a manner that the seat belt winding means is biased and thus, the seat belt can be easily fastened and pressure on a passenger's body can be alleviated.

In accordance with the present invention, there is provided a means for winding a seat belt including: a buckle sensor unit for sensing the coupling between a buckle arranged in a seat and a tongue plate provided in the seat belt; a slack sensor unit for sensing slack in the seat belt on the basis of the operation of a slip joint; a seat belt winding unit having a motor for winding the seat belt; and a control circuit unit responsive to a signal from the buckle sensor unit and the slack sensor unit for generating a signal for controlling the seat belt winding unit. The control circuit unit includes a reverse rotation detection element for detecting a reverse rotation of the motor, a motor load detection element for detecting the load of the motor, and a motor driving element for driving the motor.The driving of the motor driving element is carried out when the reverse rotation of the motor is detected.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a view showing a seat belt winding apparatus according to an embodiment of the present invention; Figs. 2 and 3 are views showing respective arrangements of a retractor section shown in Fig. 1; Figs. 4 to 6 are views showing respective arrangements of a slip joint of the apparatus shown in Fig. 1; Fig. 7 is a circuit diagram showing a configuration of a control circuit of the apparatus shown in Fig. 1; Fig. 8 is a waveform chart showing waveforms of signals at respective portions in the circuit shown in Fig. 7; Fig. 9 is a flow chart for explaining an operation of the circuit shown in Fig. 7; Fig. 10 is a view showing another embodiment of a control circuit; and Fig. 11 is a waveform chart showing waveforms of signals at respective portions in the circuit shown in Fig. 10.

DESCRIPTION OF THE PREFERRED EMBODI MENT Figure 1 shows a seat belt winding apparatus according to an embodiment of the present invention. Figures 2 and 3 show respective arrangements of a retractor section shown in Fig. 1. Details of the apparatus shown in Fig. 1 are given in the seat belt winding apparatus described in Japanese Patent Application No. 58-102243 filed by the present applicant.

In the apparatuses shown in Figs. 1 to 3, reference numeral 10 denotes a retractor casing. The retractor casing 10 is fixed to a vehicle by a bolt (not shown) inserted through a hole 101. A belt winder axis 11 having a recess 111 and a through hole 11 2 is rotatably held by the retractor casing 1 0. A loop portion 1 21 is formed from one end of the seat belt 1 2 of a three-point seat belt system and joins it to the belt winder axis 11. A rod 13 is inserted in the loop portion 121 in the recess 111 of the belt winder axis 11 in such a manner that the seat belt 1 2 cannot be removed from the belt winder axis 11.

A motor 20 which serves as a driving means for winding the seat belt is disposed on the retractor casing 10, and an output shaft 21 of the motor 20 is directly engaged and interlocked with the belt winder axis 11.

In Fig 2, the belt winder axis 11 is rotated counterclockwise by the motor 20. When the seat belt 1 2 is pulled out from the retractor casing 10, the output shaft 21 of the motor 20 is rotated by this pulling force, and the belt winder axis 11 is rotated clockwise, as shown in Fig. 3.

A pendulum 31 is swingably held by a bracket 30 fixed to the retractor casing 10. In the event of a vehicle collision or the like, the sudden change of direction of the vehicle caused by the collision causes the pendulum 31 to swing and thereby push up a pawl 32.

A projection 321 of the pawl 32 is thus engaged with a gear 33 fixed to the belt winder axis 11, thereby locking and preventing rotation of the belt winder axis 11.

The seat belt 12, which can be pulled out from the retractor casing 10, is inserted in and held by a slip joint 4 provided above the retractor casing 10, as shown in Fig. 4, and is connected through a tongue plate 50 to an anchor ANC mounted at one side of a seat.

The tongue plate 50 can be detachably fastened to a buckle 51 mounted on the other side of the seat. In use, the tongue plate 50 is coupled with the buckle 51, thereby fastening the seat belt 1 2 when worn by a passenger.

The buckle 51 has a built-in buckle sensor 52, which detects whether or not the tongue plate 50 is coupled to the buckle 51. Thus, the buckle sensor 52 constitutes a sensor of the seat belt 1 2 for detecting whether or not the driver has fastened the seat belt 1 2.

The slip joint 4 has a ring portion 41 having a hole 411 through which the seat belt 1 2 passes, and a plate portion 42 fixed to the ring portion 41. The plate portion 42 has a hole 421, as shown in Fig. 5. The hole 421 of the plate portion 42 is rotatably engaged with a bolt 44 fixed to a vehicle frame 43 in such a manner that the slip joint 4 is rotatable about the bolt 44.

A collar 45 is fitted around the bolt 44, and is held between a step portion 441 formed in the bolt 44 and the vehicle frame 43. An insulating collar 46 is fixed on and surrounds an outer surface of the collar 45. A flange portion 461 is integrally formed on the insulating collar 46 in such a manner that it extends externally along the radial direction.

A coil spring 61, having an inner diameter larger than the outer diameter of the insulating collar 46, is arranged in such a manner that it is substantially concentrical with the insulating collar 46, and a stationary end 611 of the coil spring 61 is fixed to the flange portion 461 of the insulating collar 46. A movable end 61 2 of the coil spring 61 is fixed to a hole 621 of a cylindrical protective cover 62 fixed to the plate portion 42 of the slip joint 4 by screws.

The coil spring 61 assists the slip joint 4 to move in accordance with the amount of slack in the seat belt 1 2, that is, the slip joint 4 moves from the position shown in Fig. 6 to that shown in Fig. 4. Thus, when there is slack in the seat belt 1 2, the slip joint 4 is quickly returned to the position shown in Fig.

4 by its own weight and the biasing force of the coil spring 61.

A base terminal 91 of a conductor is provided on an outer surface of the insulating collar 46 by means of adhesion or plating, and a movable contact terminal 92 for the terminal 91 is integrally formed near the movable end 612 of the coil spring 61. The base terminal 91 and the movable contact terminal 92 constitute a slack sensor 9 which detects slack in the seat belt 1 2.

Figure 7 shows a circuit configuration of a control circuit CONT in the apparatus shown in Fig. 1, and Fig. 8 is a timing chart thereof.

In Fig. 7, reference numerals 701 and 702 denote filter circuits; 705 and 707, D flipflops; 7061, 7091, 7041, 7082, and 7081, operational amplifiers; 52, the buckle sensor; 9, the slack sensor; 710, a motor driver; 704, a motor reverse rotation detector as a reverse rotation detecting means; 708, a motor soft driver for gradually increasing a driving torque of the motor; 706, a motor driving time lag circuit; and 703, a predetermined interval motor driver. When contact between the slack sensor 9 and the buckle sensor 52 is broken.

i.e., OFF, the filter circuits 701 and 702 are set at H level. A signal from the buckle sensor 52 is supplied to the filter circuit 701, and a signal from the slack sensor 9 is supplied to the filter circuit 702. The motor 20 is connected to the motor driver 71 0.

Operation of the apparatus shown in Fig. 1 will be described hereinafter with reference to Fig. 8. When a passenger is wearing the seat belt 1 2. and the tongue plate 50 is coupled with the buckle 51, a switching signal from the buckle sensor 52 is turned ON and a signal T, representing a predetermined interval T1 is generated from the predetermined interval motor driver 703. The motor 20 is driven for the interval T, by the motor driver 710 in response to the signal from the driver 703. Thus, slack in the seat belt 1 2 is taken up without discomfort to the passenger. This state is indicated by reference numeral 81 in Fig. 8.

When the buckle sensor 52 is in the coupled (ON) state, and there is slack in the seat belt 12, the motor soft driver 708 generates a signal having a predetermined frequency whose duty gradually increases in response to a signal from the slack sensor 9. The signal from the motor soft driver 708 is supplied to the motor 20 by the motor driver 710 in such a manner that the motor 20 is slowly driven to take up any slack in the seat belt 1 2. The motor load is detected by a motor load detector 709. When the motor load reaches a predetermined value, the motor load detector 709 generates a stop signal for stopping the rotation of the motor 20, and the motor 20 is stopped. This state is indicated by reference numerals 83a, 83b, and 83c in Fig. 8.

When the buckle 51 is not coupled and the slack sensor 9 is turned on, the time lag circuit 706 is operated and the motor 20 is driven after a predetermined interval T,. Here, also, the motor load detector 709 detects the motor load. When the motor load reaches the predetermined value, the motor load detector 709 generates the stop signal to stop the motor 20. This state is indicated by reference numerals 84a, 84b, and 84c in Fig. 8.

The slack sensor 9 can detect slack in the seat belt 1 2 between the retractor casing 10 and the slip joint 4 and between the slip joint 4 and the buckle 51. When there is slack in a portion of the seat belt 1 2 located between the buckle 50 and the anchor ANC, or when the seat belt 1 2 is pulled out, the belt winder axis 11 and the motor 20 are rotated in a reverse direction. A negative electromotive force is generated from the motor 20 by this reverse rotation. The negative electromotive force is detected by the motor reverse rotation detector 704 and the motor 20 is driven after the pulling out operation.In this case, when the buckle is uncoupled, the time lag circuit 706 is operated to drive the motor 20 after the predetermined interval T,. When the motor load reaches the predetermined value, the motor 20 is stopped by the motor load detector 709. This state is indicated by reference numerals 85a, 85b, and 85c in Fig. 8.

When the buckle is in the coupled state, after the seat belt 1 2 is pulled out, the motor 20 is slowly driven by the motor soft driver 708. When the motor load reaches the predetermined value, the motor 20 is stopped by the motor load detector 709. This state is indicated by reference numerals 86a, 86b, and 86c in Fig. 8.

When the driver releases the tongue plate 50 from the buckle 51, the switch in the buckle'sensor 52 is turned OFF and the signal T, is generated from the predetermined interval motor driver 703. The motor 20 is driven for the interval T, by the motor driver 710 in response to the signal T1, thus winding-up the seat belt 1 2. This state is indicated by reference numeral 82 in Fig. 8.

Figure 9 is a flow chart showing the steps of the operation of the control circuit shown in Fig. 7, as follows.

(i) In steps S101 to Si 04. when the buckle is coupled or uncoupled, the belt is wound up and the motor is stopped after the predetermined interval T1.

(ii) In steps S105 to S108, when the seat belt is pulled out and slack is detected by the slack sensor after the pulling out operation is completed, the belt is immediately wound-up.

In this case, the winding-up operation differs depending upon whether the buckle is coupled or uncoupled.

(iii) In steps S109 to S113, when the buckle is coupled, the seat belt is gradually wound-up. The winding-up operation is stopped when the motor load reaches the predetermined value.

(iv) In steps S110 to S113, when the buckle is uncoupled. the winding-up operation of the seat belt starts after the predetermined interval To When the motor load reaches the predetermined value, the winding-up operation is stopped.

Figure 10 shows another embodiment of a control circuit, and Fig. 11 shows a timing chart of an operation thereof. In the circuit shown in Fig. 10, the slack sensor 9 is turned ON when the buckle is coupled. and the motor 20 is gradually driven by the motor soft driver 708 in the same manner as described above. However, the motor 20 is stopped upon detection of the trailing edge of the signal from the slack sensor 9. This state is indicated by reference numerals 87a, 87b, and 87c in Fig. 11. The remaining operation of the control circuit is substantially the SAlr: as that in Fig. 8. The circuit shown in Fig. 1 D is substantially the same as that in Fig. 7 except for the inclusion of a NOT gate 721.

an AND gate 722, and an OR gate 723.

Claims

1. A device for winding a seat belt comprising: a buckle sensor means for sensing the coupling between a buckle arranged in a seat and a tongue plate provided on the seat belt; a slack sensor means for sensing slack in the seat belt on the basis of the operation of a slip joint; a seat belt winding means having a motor for winding-up the seat belt; and a control circuit means responsive to the signal from said buckle sensor means and said slack sensor means for generating a signal for controlling said seat belt winding means; said control circuit means including a reverse rotation detection element for detecting a reverse rotation of said motor, a motor load detection element for detecting the load of said motor, and a motor driving element for driving said motor; the driving of said motor driving element being carried out when the reverse rotation of said motor is detected.

2. A device according to claim 1, wherein the control by said control circuit means is carried out in such a manner that the motor is driven for a predetermined duration when said buckle is coupled with said tongue plate.

3. A device according to claim 1, wherein the control by said control circuit means is carried out in such a manner that the motor is driven at approximately zero of the predetermined interval on the basis of the signal from said slack sensor means while the belt is in the fastened state wherein the buckle and tongue plate are coupled.

4. A device according to claim 1, wherein the control by said control circuit means is carried out in such a manner that the driving of the motor is stopped in response to the signal indicating the change from an OFF state to an ON state from said slack sensor means. which signal corresponds to the change from the slack state to the non-slack state of said seat belt while said seat belt is in the fastened state wherein the buckle and tongue plate are coupled.

5. A device for winding a seat belt substantially as described herein with reference to the accompanying drawings.