Seat belt retractor and seat belt device

• US 20060071111A1
• Filed: 09/22/2005
• Published: 04/06/2006
• Est. Priority Date: 10/04/2004
• Status: Active Grant

• Current Assignee: Takata Corporation (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Takata Corporation (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Tanaka, Koji, Inuzuka, Koji
• Granted Patent: US 7,380,740 B2
• Time in Patent Office: Days
• US Class Current: 242/374
• CPC Class Codes: B60R 2022/287 of torsion rods or tubes
• CPC Class Codes: B60R 2022/444 the additional retraction device being an electric actuator
• CPC Class Codes: B60R 2022/4666 characterised by electric actuators
• CPC Class Codes: B60R 2022/468 characterised by clutching means between actuator and belt reel
• CPC Class Codes: B60R 22/46 Reels with means to tension the belt in an emergency by forced winding upelectrical circuits for triggering safety arrangements B60R21/01 ; tensioners using reels only guiding the belt during normal use, e.g. splitted reels B60R22/195
• CPC Class Codes: B60R 22/4676 comprising energy-absorbing means operating between belt reel and retractor frame

Abstract

A seat belt retractor is provided in which two winding performances are achieved while reduced power consumption of a motor and simplified control of the motor are also achieved. A clutch gear is meshed with a carrier gear by rotation of a motor in the normal direction. Accordingly, a low reduction ratio power transmission mode is set so that a seat belt is wound up at a high speed and with low torque. As slack of the seat belt is removed and the belt load increases, the clutch pawl becomes possible to be engaged with the internal gear. As the motor current increases and exceeds a preset value, the motor rotates reversely so that the clutch gear separates from the carrier gear. Therefore, a high reduction ratio power transmission mode is set so that the belt is wound up at a low speed and with high torque.

Claims

1. A seat belt retractor, comprising:

a spool for winding up a seat belt;

a motor configured to generate rotational torque for rotating the spool; and

a power transmission mechanism configured to transmit the rotational torque of the motor to the spool, the seat belt being wound on the spool by the rotational torque of the motor,

wherein the power transmission mechanism includes a low reduction ratio power transmission mode in which the rotational torque of the motor is transmitted to the spool at a high speed and with low torque and a high reduction ratio power transmission mode in which the rotational torque of the motor is transmitted to the spool at a low speed and with high torque,

wherein the seat belt retractor further comprises a power transmission mode switching mechanism that selectively sets the power transmission mechanism into either the low reduction ratio power transmission mode or the high reduction ratio power transmission mode, and

a controller configured to control the action of the power transmission mode switching mechanism to switch the mode between the low reduction ratio power transmission mode and the high reduction ratio power transmission mode by controlling the rotational direction of the motor to be changed between the normal direction or the reverse direction.

2. The seat belt retractor according to claim 1, wherein the controller controls the rotational direction of the motor to be changed between the normal direction or the reverse direction based on the motor current to be supplied to the motor.

3. The seat belt retractor according to claim 2, wherein the controller sets the power transmission mechanism to the low reduction ratio power transmission mode when the motor current value is lower than the preset current value, while the controller sets the power transmission mechanism to the high reduction ratio power transmission mode when the motor current value exceeds the preset current value.

4. The seat belt retractor according to claim 1, wherein a mechanism for the high reduction ratio power transmission mode of the power transmission mechanism includes a planetary gear train that comprises a carrier, a sun gear, a planet gear, and an internal gear.

5. The seat belt retractor according to claim 1, wherein the power transmission mechanism further includes a power transmission insulating mode in which the rotational torque of the motor is not transmitted to the spool, and

the power transmission mode switching mechanism selectively sets the power transmission mechanism to either one of the low reduction ratio power transmission mode, the high reduction ratio power transmission mode, and power transmission insulating mode.

6. The seat belt retractor according to claim 5, wherein when the power transmission mechanism is in the power transmission insulating mode, a torque transmission passage between a clutch gear and a carrier gear are insulated.

7. A seat belt device, comprising:

a seat belt retractor configured to wind up a seat belt;

a tongue that is slidably supported to the seat belt; and

a buckle releasably latched to the tongue,

wherein the seat belt retractor includes;

a spool for winding up the seat belt;

a motor configured to generate rotational torque for rotating the spool; and

a power transmission mechanism configured to transmit the rotational torque of the motor to the spool, the seat belt being wound on the spool by the rotational torque of the motor,

wherein the power transmission mechanism includes a low reduction ratio power transmission mode in which the rotational torque of the motor is transmitted to the spool at a high speed and with low torque and a high reduction ratio power transmission mode in which the rotational torque of the motor is transmitted to the spool at a low speed and with high torque,

wherein the seat belt retractor further comprises a power transmission mode switching mechanism that selectively sets the power transmission mechanism into either the low reduction ratio power transmission mode or the high reduction ratio power transmission mode, and

a controller configured to control the action of the power transmission mode switching mechanism to switch the mode between the low reduction ratio power transmission mode and the high reduction ratio power transmission mode by controlling the rotational direction of the motor to be changed between the normal direction or the reverse direction.

8. The seat belt device according to claim 7, wherein when the power transmission mechanism is in low reduction ration power transmission mode, the motor rotates in a belt winding direction and an internal gear freely rotates, thus, a low speed and high torque transmission passage is insulated.

9. The seat belt device according to claim 7, wherein the power transmission mechanism further includes a power transmission insulating mode in which the rotational torque of the motor is not transmitted to the spool.

10. The seat belt device according to claim 9, wherein the seat belt retractor includes a belt storage mode in which the seat belt is fully wound on the spool and the power transmission mechanism is set in the power transmission insulating mode.

11. The seat belt device according to claim 9, wherein the seat belt retractor includes a belt unwinding mode in which the seat belt is withdrawn from the spool and the power transmission mechanism is set in the power transmission insulating mode.

12. The seat belt device according to claim 7, wherein the seat belt retractor includes a belt winding mode for fitting in which the seat belt is withdrawn, the tongue is latched to the buckle and an excessively withdrawn amount of the seat belt is rewound and the power transmission mechanism is set in the low reduction ration power transmission mode.

13. The seat belt device according to claim 9, wherein the seat belt retractor includes a normal use mode that follows after the belt winding mode for fitting and the power transmission mechanism is set in the power transmission insulating mode.

14. The seat belt device according to claim 7, wherein the seat belt retractor includes a warning mode in which a winding action of the seat belt is repeated a predetermined number of times in which alternating high and low tension is applied to the seat belt.

15. The seat belt device according to claim 7, wherein the seat belt retractor includes an emergency mode in which the power transmission mechanism switches from a power transmission insulating mode, to the low reduction ratio power transmission mode and is then switched into the high reduction ration power transmission mode.

16. The seat belt device according to claim 7, wherein the controller controls the rotational direction of the motor to be changed between the normal direction or the reverse direction based on the motor current to be supplied to the motor.

17. The seat belt device according to claim 16, wherein the controller sets the power transmission mechanism to the low reduction ratio power transmission mode when the motor current value is lower than the preset current value, while the controller sets the power transmission mechanism to the high reduction ratio power transmission mode when the motor current value exceeds the preset current value.

18. The seat belt device according to claim 7, wherein a mechanism for the high reduction ratio power transmission mode of the power transmission mechanism includes a planetary gear train that comprises a carrier, a sun gear, a planet gear, and an internal gear.

19. A seat belt device including a retractor for winding up a seatbelt and a controller configured to change the rotational direction of a retractor motor between the normal direction and the reverse direction, wherein the retractor is configured to switch between a low reduction ratio power transmission mode and a high reduction ratio power transmission mode when the rotational direction of the retractor motor is changed.