초록 ▼

An electric retractor extracts and retracts a seat belt in response to tension in the seat belt. The electric retractor may include a spool rotatably attached to a retractor frame. A seat belt is wound on the spool. The spool is rotated by a motor via a worm gear system that permits limited axial mo

An electric retractor extracts and retracts a seat belt in response to tension in the seat belt. The electric retractor may include a spool rotatably attached to a retractor frame. A seat belt is wound on the spool. The spool is rotated by a motor via a worm gear system that permits limited axial motion of the worm, but generally prevents the motor from being back-driven by tension in the seat belt to prevent forced seat belt extraction. The gear system may also cut off power to the motor in the event of excessive seat belt tension to prevent further payout of the seat belt. A senses tension in the seat belt and activates the motor to retract or extract the seat belt from the retractor. An emergency control system may override the web guide control in response to abnormal vehicle dynamics to provide reversible pre-crash pretensioning and/or crash pretensioning.

대표청구항 ▼

The invention claimed is: 1. An electric seat belt retractor comprising: a spool connected to a seat belt wound around the spool, the spool being rotatable about an axis fixed within a retractor frame; the retractor frame comprising a belt opening at one end of the retractor frame which allows ext

The invention claimed is: 1. An electric seat belt retractor comprising: a spool connected to a seat belt wound around the spool, the spool being rotatable about an axis fixed within a retractor frame; the retractor frame comprising a belt opening at one end of the retractor frame which allows extraction and retraction of the seat belt from the retractor and wherein the tension in the seat belt is measured by a tension sensor in contact with the seat belt, the tension sensor comprising an arm which extends over the belt opening, one end of the arm being pivotally attached to the retractor frame, the other end of the arm being in contact with a portion of the seat belt extending from the belt opening, and wherein the arm pivots in response to tension in the seat belt; and a motor coupled to the spool to rotate the spool, the motor being in electrical communication with a circuit which activates and deactivates the motor to extract and retract the seat belt in response to tension in a portion of the seat belt extending from the spool. 2. The electric seat belt retractor of claim 1, wherein the drive shaft is connected by a first connector and a second connector to the retractor frame and wherein the first connector comprises the stop, the seat belt retractor further comprising a spring around the drive shaft between the first connector and the worm such that the spring biases the worm and drive shaft to place the worm and drive shaft in operable engagement with the worm wheel in response to the torque being less than the bias of the spring. 3. The electric seat belt retractor of claim 2, wherein in response to the torque being greater than the bias of the spring, the worm and drive shaft slide axially and compress the spring against the stop, the retractor further comprising a switch in electrical communication with the circuit and positioned such that sliding the drive shaft in response to the torque activates the switch to prevent power flow within the circuit to the motor. 4. The electric seat belt retractor of claim 3, wherein in response to the arm extending from the belt opening at an angle between about zero and about fort-five degrees, the tension sensor provides power in the circuit which activates the motor to retract the seat belt onto the spool. 5. The electric seat belt retractor of claim 3, wherein in response to the arm extending between about forty-five degrees and about ninety degrees from the belt opening, the tension sensor provides power in the circuit which activates the motor to extract the seat belt from the spool. 6. The electric seat belt retractor of claim 3, wherein in response to the arm extending at about forty-five degrees from the belt opening, the circuit provides no power to the motor. 7. The electric seat belt retractor of claim 3, wherein the tension sensor comprises a potentiometer in electrical communication with the circuit and connected to the arm such that pivoting of the arm determines the level of power provided to the circuit. 8. The electric seat belt retractor of claim 3, wherein the tension sensor comprises a spring which biases the arm towards the belt opening. 9. The electric seat belt retractor of claim 3, wherein the tension sensor comprises a web guide for the electric seat belt retractor. 10. The electric seat belt retractor of claim 1, further comprising a worm wheel coaxially connected to one end of the spool for rotating the spool. 11. The electric seat belt retractor of claim 10, further comprising a worm fixed to a drive shaft, the drive shaft connected to the retractor frame such that the drive shaft is rotatable and axially slidable, the worm being positioned along the drive shaft to operably engage the worm wheel. 12. The electric seat belt retractor of claim 11, wherein in response to an extraction force applied to the seat belt, a torque is created in the worm wheel that forces the worm wheel to slide the worm and drive shaft together axially until the worm contacts a stop, the worm remaining engaged with the worm wheel to prevent further rotation of the worm wheel in the direction of seat belt extraction. 13. An electric seat belt retractor comprising: a spool connected to a seat belt which is wound around the spool, the spool being rotatable about an axis fixed within a retractor frame; a motor coupled to the spool to rotate the spool, the motor being in electrical communication with a circuit which activates and deactivates the motor to extract and retract the seat belt in response to tension in the seat belt measured by a tension sensor in direct contact with a portion of the seat belt extending from the spool; and an automatic locking system in electrical communication with the circuit comprising: a rotation sensor positioned to detect rotations of the spool, wherein, in response to the automatic locking system being activated, the circuit activates the motor for seat belt retraction and prevents extraction of the seat belt. 14. The electric retractor of claim 13, wherein in response to the torque on the worm wheel in the direction of extraction being greater than the bias force of the compression spring, the worm wheel forces the worm and drive shaft to slide axially and the worm compresses the compression spring against the first pillow block which prevents further axial movement of the worm and drive shaft and wherein the axial movement of the drive shaft extends the drive shaft past the first pillow block to activate a switch in electrical communication with the circuit such that power to the motor is interrupted. 15. The electric retractor of claim 13, wherein the automatic locking system further comprises a counting module which receives a signal from the rotation sensor for each rotation detected, the counting module being in electrical communication with the rotation sensor and the circuit. 16. The electric retractor of claim 15, wherein the counting module increments a count for each rotation of the spool in the direction for seat belt extraction and decrements the count for each rotation of the spool in the direction of seat belt retraction such that in response to the count reaching an activation threshold the automatic locking system is activated and in response to the count reaching a deactivation threshold the automatic locking system is deactivated. 17. The electric retractor of claim 15, wherein the activation threshold corresponds to substantially all of the seat belt being extracted from the retractor and wherein the deactivation threshold corresponds to substantially all of the seat belt being retracted into the retractor. 18. The electric retractor of claim 15, wherein the electric retractor is installed in a vehicle, the electric retractor further comprising an emergency control system in electrical communication with the circuit such that the emergency control system is capable of overriding the tension sensor and activating the motor to provide pre-crash pretensioning of the seat belt in response to vehicle dynamics. 19. The electric retractor of claim 18, wherein the emergency control system is capable of pretensioning the seat belt in response to activation of a crash sensor in the vehicle. 20. The electric retractor of claim 18, wherein the emergency control system activates the motor to reverse the pre-crash pretensioning in response to vehicle dynamics and a crash sensor not being activated. 21. The electric retractor of claim 18, wherein the emergency control system comprises a vehicle dynamics sensor which detects abnormal vehicle dynamics for the vehicle and signals the emergency control system which responds by activating the motor to retract the seat belt onto the spool to provide pre-crash pretensioning. 22. The electric retractor of claim 21, wherein the emergency control system is in electrical communication with at least one crash sensor, and wherein in response to the at least one crash sensor being activated, the emergency control system activates the motor to retract the seat belt onto the spool to provide crash pretensioning. 23. The electric retractor of claim 22, wherein the motor is activated to provide a maximum retraction torque on the spool available from the motor. 24. The electric retractor of claim 13, further comprising a worm wheel that rotates the spool about the fixed axis, the worm wheel being coaxially connected to one end of the spool. 25. The electric retractor of claim 24, further comprising a drive shaft connected by a first pillow block and a second pillow block to the retractor frame such that the drive shaft is rotatable and axially slidable, a worm fixed to the drive shaft is positioned to operably engage the worm wheel such that rotation of the drive shaft rotates the worm to drive the worm wheel. 26. The electric retractor of claim 25, further comprising a compression spring around the drive shaft between the first pillow block and the worm such that the spring biases the worm restricting the drive shaft from sliding axially in response to an extraction force which generates a torque on the worm wheel in a direction to pay out the seat belt, the torque being less than the bias force of the compression spring. 27. An electric seat belt retractor installed in a vehicle, the electric seat belt retractor comprising: a spool connected to a seat belt which is wound around the spool, the spool being rotatable about an axis fixed within a retractor frame; a worm wheel that rotates the spool about the fixed axis, the worm wheel being coaxially connected to one end of the spool; a rotatable drive shaft having a worm fixed thereto, the drive shaft connected by a first pillow block and a second pillow block to the retractor frame such that the drive shaft is rotatable and axially slidable, the worm being positioned along the drive shaft to operably engage the worm wheel such that rotation of the drive shaft rotates the worm to drive the worm wheel; a driving means for rotating the drive shaft; wherein the driving means is in electrical communication with a control means for activating and deactivating the driving means to extract and retract the seat belt in response to a belt detector means for detecting a tension force in a portion of the seat belt extending from the spool by detecting the relative position of the belt detector means with respect to the portion of the seat belt extending from the spool; and a biasing means for preventing the drive shaft from sliding axially in response to torque introduced in the worm wheel by the load which is less than the bias provided by the biasing means. 28. The electric seat belt retractor of claim 27, further comprising a dynamics detector means for detecting a vehicle dynamic and a crash detector means for detecting a vehicle accident situation and an emergency control means in communication with the dynamics detector means and crash detector means, the emergency control means overriding the control means and activating the driving means to retract the seat belt to provide pre-crash pretensioning in response to the dynamics detector means detecting that a vehicle dynamic is outside a threshold range. 29. The electric seat belt retractor of claim 28, wherein in response to the vehicle dynamic returning to within the threshold range and the crash detector means providing no indication of an accident, the emergency control means returns control of the electric seat belt retractor to the control means. 30. The electric seat belt retractor of claim 28, wherein the emergency control means overrides the control means and activates the driving means to retract the seat belt to provide crash pretensioning in response to the crash detector means signaling an accident situation and the dynamics detector means signaling that a vehicle dynamic is outside a threshold range.