WO2004103782A1 - Systeme de retracteur electrique de ceinture de securite - Google Patents

Systeme de retracteur electrique de ceinture de securite Download PDF

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Publication number
WO2004103782A1
WO2004103782A1 PCT/US2004/015814 US2004015814W WO2004103782A1 WO 2004103782 A1 WO2004103782 A1 WO 2004103782A1 US 2004015814 W US2004015814 W US 2004015814W WO 2004103782 A1 WO2004103782 A1 WO 2004103782A1
Authority
WO
WIPO (PCT)
Prior art keywords
seat belt
tension
spool
retractor
motor
Prior art date
Application number
PCT/US2004/015814
Other languages
English (en)
Inventor
Krzysztof W. Karwaczynski
Michael K. Hishon
Samuel D. Engler
Original Assignee
Autoliv Asp, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US10/440,698 external-priority patent/US6935590B2/en
Priority claimed from US10/459,353 external-priority patent/US7140571B2/en
Application filed by Autoliv Asp, Inc. filed Critical Autoliv Asp, Inc.
Priority to EP04752769A priority Critical patent/EP1625055A1/fr
Publication of WO2004103782A1 publication Critical patent/WO2004103782A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R22/00—Safety belts or body harnesses in vehicles
    • B60R22/34—Belt retractors, e.g. reels
    • B60R22/44—Belt retractors, e.g. reels with means for reducing belt tension during use under normal conditions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R22/00—Safety belts or body harnesses in vehicles
    • B60R22/34—Belt retractors, e.g. reels
    • B60R22/46—Reels with means to tension the belt in an emergency by forced winding up
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D15/00—Control of mechanical force or stress; Control of mechanical pressure
    • G05D15/01—Control of mechanical force or stress; Control of mechanical pressure characterised by the use of electric means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R22/00—Safety belts or body harnesses in vehicles
    • B60R22/34—Belt retractors, e.g. reels
    • B60R22/44—Belt retractors, e.g. reels with means for reducing belt tension during use under normal conditions
    • B60R2022/4473—Belt retractors, e.g. reels with means for reducing belt tension during use under normal conditions using an electric retraction device
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R22/00—Safety belts or body harnesses in vehicles
    • B60R22/34—Belt retractors, e.g. reels
    • B60R22/46—Reels with means to tension the belt in an emergency by forced winding up
    • B60R2022/4666—Reels with means to tension the belt in an emergency by forced winding up characterised by electric actuators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
    • B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
    • B60R21/015—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting the presence or position of passengers, passenger seats or child seats, and the related safety parameters therefor, e.g. speed or timing of airbag inflation in relation to occupant position or seat belt use
    • B60R21/01512—Passenger detection systems
    • B60R21/01544—Passenger detection systems detecting seat belt parameters, e.g. length, tension or height-adjustment
    • B60R21/0155—Passenger detection systems detecting seat belt parameters, e.g. length, tension or height-adjustment sensing belt tension

Definitions

  • the present invention relates to seat belt systems designed to protect the occupants of a vehicle during a collision. More specifically, the invention relates to an electric seat belt retractor system and sensor which is uniquely capable of protecting an occupant during normal use, pre-crash situations, and crash situations, and is capable of constantly and dynamically adjusting to the positioning of the occupant.
  • a "control system” may be defined as a system in which an operation is to be perforaied (or omitted) in a manner determined by measuring some characteristic of the system. Thus, efficient operation of the system can be maintained despite relatively unpredictable changes in the system.
  • the present invention has application to a wide variety of control systems.
  • seat belts may prevent the occupant of a vehicle from striking the interior of the vehicle or other objects within the vehicle, including other occupants.
  • Seat belts aid in keeping the occupant inside the vehicle during a roll-over or other accident situation to enhance the probability of survival and injury avoidance.
  • Seat belts may also keep the driver behind the wheel and in control of the vehicle prior to an impending or potential collision, averting additional damage or injuries.
  • Seat belts also enhance the effectiveness of other safety devices. For example, in a vehicle with airbags, a seat belt keeps the occupant in the seat so that the airbag can better protect the occupant.
  • Seat belts vary in their configuration, but one common type of seat belt is the three point safety harness.
  • a three point safety harness includes a lap belt and a shoulder strap that cooperate to anchor an occupant on each side of his/her lap and at one shoulder, i one commonly employed three-point safety harness configuration, the seat belt webbing traverses the occupant's upper body in a diagonal fashion, passes through a latch plate, and then traverses the occupant's lap.
  • the latch plate is fastened to a buckle, which is secured to the vehicle to restrain both the occupant's lower and upper body.
  • One end of the webbing is typically anchored to the vehicle. The other end is secured by a seat belt retractor.
  • three point safety harnesses are usually adjustable to provide proper safety and comfort.
  • a seat belt retractor allows the safety harness to be adjustable and to lock the webbing in the event of an accident.
  • Conventional seat belt retractors include webbing anchored at one end to a spool. Rotation of the spool is controlled for extraction and retraction of the webbing by a combination of various ratchet wheels, springs, lock dogs, pawls, gears, and the like.
  • the shoulder strap Preferably, in a three-point safety harness, the shoulder strap rests lightly on the occupant's shoulder and allows the occupant's upper torso relatively free movement. However, many occupants fail to properly adjust the tension in the safety harness once the seat belt has been fastened.
  • seat belt retractors have been designed to automatically remove excess slack from the shoulder strap. Generally, this is done by providing a constant bias on the spool in the direction of webbing retraction.
  • seat belt systems usually contain substantial slack, often 120 mm or more. This is clearly not ideal in that the slack can defeat the effectiveness of the seat belt in a crash situation.
  • an electric seat belt retractor is controlled based on sensing tension in the seat belt to provide powered extraction and retraction of the seat belt.
  • the electric seat belt retractor provides pre-crash pretensioning, crash pretensioning, and automatic locking, in addition to the existing functions of emergency locking, extraction, and retraction.
  • the present invention provides an electrical retractor which overcomes many of the limitations of the prior art.
  • the present invention provides constant and dynamic extraction and retraction of the seat belt webbing in order to follow the occupant's motion about the vehicle. This provides substantially increased comfort to the occupant, while at the same time maintaining a high degree of safety and effectiveness.
  • a sensor associated with the seat belt system retracts the seat belt webbing until the occupant is in a safe and secure position. This position is maintained in the event of a crash such that the occupant is properly positioned and safely restrained by the seat belt. As an added benefit, the occupant is restrained in a proper position to receive the added protective benefits of an airbag or supplemental restrain system.
  • a web guide lever is employed together with a potentiometer or any angular, linear, or photoelectric sensor.
  • Other types of sensors could also be employed such as linear variable displacement transducers (LNDT's), optical sensors, Hall Effect sensors, pressure sensors, piezoelectric or resistance-based load cells, and the like.
  • the present invention provides a previously unknown type of secondary electromechanical feedback.
  • Servo control is used to greatly improve motor control compared to known motor implementations. More precisely, a sensor may be mounted to an axle of a web guide lever to supply exact information about webbing dynamics. This information allows the servo amplifier to adjust the direction and speed of the retractor motor in a precise manner. Thus, minimum web tension can be achieved in the seat belt system to assure ride comfort as well as rapid response to any fast or slow changes in the webbing configuration.
  • the system allows the seat belt webbing to be extracted and reduces the force when worn for improved occupant comfort.
  • the motor drives the mechanism described below to retract the seat belt webbing with sufficient force to pull the occupant back more firmly into the seat and to attain a more favorable position for air bag deployment in the event of a crash.
  • the mechanism described below also provides the structural "lock-up" function necessary to support belt loading and restrain the occupant during a crash.
  • the system of the present invention provides a fail-safe mechanism whereby in the event of the loss of electrical power, the mechanism is locked in place to provide protection to the occupant.
  • the electric seat belt retractor of the present invention provides automatic extraction and retraction of the seat belt and other safety features using a unique mechanical configuration.
  • the electric seat belt retractor of the present invention includes a gear assembly which may include a spool, a worm wheel, and a worm.
  • the spool is rotatable about an axis within a retractor frame.
  • a seat belt is connected to and wound around the spool.
  • the worm wheel is coaxially connected to one end of the spool axis.
  • the worm connected to a drive shaft, operably engages the worm wheel. Rotation of the drive shaft rotates the worm which drives the worm wheel about the spool axis.
  • the drive shaft is connected to the retractor frame such that the drive shaft is rotatable and axially slidable.
  • the electric seat belt retractor also includes a motor coupled to the drive shaft for rotating the drive shaft.
  • the motor is electrically connected to a circuit which activates and deactivates the motor to extract and refract the seat belt in response to tension in a portion of the seat belt which extends from the spool, h response to a rapid 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 switch that cuts power to the motor and prevents further extraction.
  • the electric seat belt retractor may include a spring around the drive shaft between a connector for the drive shaft and the worm such that the spring biases the worm and drive shaft against axial movement toward the connector in response to torque created in the worm wheel when the occupant pulls against the seat belt.
  • the torque is in the direction of seat belt extraction.
  • the spring arrests translation of the worm when the spring bias becomes equal to the torque to keep the worm and drive shaft in operable engagement with the worm wheel.
  • the electric seat belt retractor may also include a tension sensor in communication with the seat belt.
  • the tension sensor may be any type of sensor which provides the necessary characteristics for operation of the system.
  • the tension sensor is in electrical communication with the circuit, hi response to changes in tension in the seat belt, the tension sensor activates the motor to refract or extract the seat belt from the electric seat belt retractor.
  • the tension sensor includes a rigid member, such as an arm, pivotally connected to a base.
  • the base is oriented generally perpendicular to the seat belt webbing.
  • the base may be oriented at almost any angle with respect to the webbing.
  • the arm is generally planar. One end of the arm is pivotally connected to the base. The other end of the arm is in direct contact with the webbing.
  • the arm is pivotable to form between about a zero degree angle and about a ninety degree angle with respect to the base.
  • the angle may range from about zero degrees and about one-hundred and eighty degrees. Of course, different configurations may allow for still different angle ranges.
  • the arm commumcates with the seat belt webbing such that movement of the webbing and changes in tension within the webbing cause the arm to pivot.
  • Movement of the webbing generally comprises sliding of the webbing past the arm and/or changes in the direction in which the webbing is drawn.
  • the webbing may pass through a passage near the unconnected end of the arm. Alternatively, the webbing simply slides past the unconnected end of the arm.
  • the seat belt webbing sensor includes a sensor in communication with the arm.
  • the sensor may be mechanically coupled to the arm.
  • the sensor may use an intangible medium such as electromagnetic energy or magnetic flux to detect movement of the ami with respect to the base.
  • the signal may represent a change in position of the arm, an angle between the arm and the base, rotational velocity or acceleration of the arm, or other information relating to pivotal motion of the arm with respect to the base.
  • the sensor may be an acceleration sensor, a velocity sensor, an angular position sensor, or the like.
  • the seat belt webbing sensor is incorporated in a feedback control system that controls an electric seat belt retractor designed to take up the seat belt.
  • the feedback control system includes a spool rotatably coupled to a retractor frame.
  • the seat belt webbing is connected to, and wound around the spool.
  • the seat belt webbing sensor senses tension in the portion of the seat belt extending from the retractor frame.
  • the spool may be rotated about its axis by an electric motor.
  • the tension sensor and motor are electrically connected to a servo amplifier.
  • the tension sensor measures a change in tension in the seat belt
  • the tension sensor causes the servo amplifier to provide a corresponding voltage to the motor to adjust the tension in the seat belt until the tension sensor measures a predetermined tension.
  • the motor is deactivated.
  • the seat belt webbing sensor, servo amplifier, and motor make up a feedback control loop.
  • the tension sensor continually sends an analog signal to the servo amplifier.
  • the servo amplifier simply amplifies the signal to enable the signal to operate the motor.
  • the analog signal is a signal for activating the motor to adjust the tension in the seat belt. As the motor rotates the spool, the tension in the seat belt is increased or decreased in accordance with the analog signal.
  • the signal is analog and originates from the tension sensor, which is directly measuring even slight changes in tension, the change in tension causes a corresponding change in the signal.
  • the motor speed is gradually decreased until the predetermined tension is reached.
  • the feedback control loop provides smooth, precise adjustments to the tension in the seat belt while minimizing or eliminating motion control errors.
  • the tension in the seat belt returns to a lower level, for example, due to release of the seat belt or engagement of the latch and the buckle, the reduced tension and the bias of the tension sensor towards the belt opening causes the tension sensor to activate the motor to retract the seat belt.
  • the tension in the seat belt increases. Increasing the tension causes the arm to pivot to form an angle of about forty- five degrees with the belt opening.
  • the tension sensor deactivates the motor. When the arm is positioned at about forty-five degrees, a comfortable amount of tension is present in the seat belt.
  • the electric seat belt retractor includes one or more systems which override the tension sensor in order to provide additional safety features.
  • an automatic locking system may activate or deactivate based on the number of rotations of the spool to prevent overextension of the seat belt.
  • the tension sensor is overridden by the automatic locking system which activates the motor for retraction but prevents extraction.
  • an emergency control system may override the tension sensor to provide reversible pre-crash pretensioning and/or crash pretensioning in response to sensors that track certain vehicle dynamics such as pitch, yaw, panic braking, loss of traction, dramatic steering wheel movement, and the like.
  • the electric seat belt retractor provides substantial advantages over conventional systems.
  • the electric seat belt retractor senses the tension in the seat belt such that a constant bias in the direction of retraction is umiecessary.
  • the worm wheel and sliding worm and drive shaft provide a safety lock which prevents unintentional extraction of the seat belt.
  • Conventional locking pawls and ratchet wheels are unnecessary.
  • the seat belt retractor provides enhanced seat belt take-up with comparatively fewer components. Stated more generally, the present invention provides enhanced structures and method for accurately controlling tension within a flexible member.
  • Figure 1 is a perspective view of one embodiment of an electric seat belt refractor
  • Figure 2A is a side view of a tension sensor of an electric seat belt retractor detecting maximum tension in the seat belt;
  • Figure 2B is a side view of a tension sensor of an electric seat belt retractor detecting minimal tension in the seat belt;
  • Figure 3 A is a side view of a worm gear drive system used in one embodiment of an electric seat belt retractor which is locked due to torque in the worm wheel;
  • Figure 3B is a side view of a worm gear drive system used in one embodiment of an electric seat belt retractor during normal operation;
  • Figure 4 is a functional block diagram for a circuit of one embodiment of an electric seat belt retractor that provides automatic locking functionality
  • Figure 5 is a perspective view of components integrated with an electric seat belt retractor to provide automatic locking
  • Figure 6 is a functional block diagram for a circuit of one embodiment which provides pre-crash pretensioning and crash pretensioning in an emergency
  • Figure 7 is a side view of a seat belt webbing sensor according to one embodiment of the invention.
  • Figure 8 is a perspective view of a seat belt webbing sensor integrated with an electric seat belt retractor;
  • Figure 9 is a side view of a seat belt webbing sensor used in a feedback control system for operating an electric seat belt retractor
  • Figure 10 is a perspective view of an alternative orientation of one embodiment of a seat belt webbing sensor.
  • Figure 11 is a functional flow diagram of a feedback control system including a seat belt webbing sensor according to the present invention.
  • phrases “connected to,” “coupled to,” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, electromechanical and thermal interaction.
  • slidingably attached to refer to forms of mechanical coupling that permit relative rotation or relative translation, respectively, while restricting other relative motion.
  • FIG. 1 With reference to Figure 1, there is illustrated a perspective view of an electric seat belt retractor 10.
  • the electric seat belt retractor 10 is shown in a configuration corresponding to installation of the retractor 10 on a B-pillar of a vehicle (not shown) for a shoulder seat belt system.
  • the retractor 10 can be installed in other locations of a vehicle.
  • the retractor 10 may be installed beside a rear seat for use in a lap and/or a shoulder seat belt system.
  • the refractor 10 may be used with a variety of lap, shoulder, and/or four or five point seat belt systems.
  • the electric seat belt retractor 10 includes a seat belt 12.
  • the seat belt 12 is seat belt webbing of about two inches in width and a length determined by factors such as the type of seat belt system using the retractor 10, the position of the refractor 10 in the vehicle, and the size of the seat (not shown).
  • one end of the seat belt is anchored to the vehicle outside the retractor 10.
  • the remainder of the seat belt 12 may be threaded through a latch plate or buckle and a D-ring before being comiected to the retractor 10.
  • the refractor 10 adjusts the seat belt 12 by paying out or retracting the seat belt 12 as needed.
  • a rewind spring (not shown) is generally used to pay out or retract the seat belt 12.
  • excess seat belt webbing 12 is taken up by the rewind spring connected to a spool 14 around which the seat belt webbing 12 is wound to form a take-up mechanism.
  • An axle 15 of the spool 14 rotates about an axis 16 secured within a refractor frame 18.
  • the spool 14 rotates to pay out and refract the seat belt 12 in response to the needs of an occupant.
  • an input gear is connected to the spool 14.
  • the input gear may take the form of a worm wheel 20 is comiected coaxially to one end of the spool 14.
  • the worm wheel 20 operably engages an input gear, which may take the form of a worm 22.
  • Rotation of the worm 22 in one direction drives the worm wheel 20 to rotate the spool 14 to pay out the seat belt 12.
  • Rotation of the worm 22 in the other direction rotates the worm wheel 20 which rotates the spool 14 to refract the seat belt 12.
  • the size and configuration of the worm wheel 20 and worm 22 may vary based on the seat belt system used with the retractor 10. Using a worm wheel 20 and worm 22 to drive the spool 14 provides high torque for extraction and retraction of the seat belt 12. In one embodiment, the gear ratio between the worm wheel 20 and worm 22 is 30:1. Alternatively, the number of teeth on the worm wheel 20 and worm 22 may be varied to provide different gear ratios.
  • the worm 22 is fixed to a drive shaft 24.
  • the worm 22 is fixed to a drive shaft 24.
  • the worm is fixed to a drive shaft 24.
  • the worm 22 and drive shaft 24 may be formed from a single piece of material.
  • the worm 22 may be connected to the drive shaft 24 using various mechanical connectors.
  • the worm 22 may be secured by one or more set screws 26.
  • pins may pass through the shaft and engage the worm 22 to allow rotation and prevent lateral movement of the worm 22 with respect to the drive shaft 24.
  • the worm 22 may be welded to the drive shaft 24.
  • the worm 22 is positioned along the drive shaft 24 to operably engage the worm wheel 20.
  • the drive shaft 24 is connected by a first connector 28 and a second connector 30 to the retractor frame 18.
  • a single connector 28 may be used.
  • the retractor frame 18 serves as a base 31 for the connector 28, 30.
  • the connectors 28, 30 are configured to secure the drive shaft 24 to the frame 18 but still allow the drive shaft 24 to rotate and slide laterally within the connectors 28, 30.
  • the connectors 28, 30 are pillow blocks.
  • the pillow blocks may be secured to the refractor frame 18 by screws or bolts.
  • the pillow blocks may include bearings (not shown) between the drive shaft 24 and a race (not shown) of the pillow block. The bearings facilitate rotational and lateral movement of the drive shaft 24 within the pillow blocks.
  • the retractor 10 includes a motor 32.
  • the motor 32 is coupled to the drive shaft 24 to rotate the drive shaft 24 in either direction.
  • the motor 32 is a DC motor.
  • the motor 32 is electrically coupled to a circuit (discussed in more detail below) which activates and deactivates the motor 32 in response to tension in a portion of the seat belt 12 which extends from the spool 14.
  • the worm 22 and drive shaft 24 move together laterally, in order for the rotating worm 22 to drive the worm wheel 20, the worm 22 is held laterally stationary.
  • the worm 22 is position on the drive shaft 24 such that the worm 22 abuts the second connector 30.
  • the second connector 30 prevents the wonn 22 from screwing past the worm wheel 20 so that the worm 22 drives the worm wheel 20.
  • the first connector 28 may laterally hold the worm 22 and drive shaft 24 for the worm 22 to drive the worm wheel 20.
  • the retractor 10 includes a compression spring 34 positioned around the drive shaft 24 in a space between the worm 22 and the first connector 28.
  • the spring 34 holds the worm 22 in operable engagement with the worm wheel 20 for driving the worm wheel 20 when paying out the seat belt 12.
  • a worm 22 and worm wheel 20 gear system can not be “back-driven.” Therefore, a driving force for the system should operate to rotate the worm 22, not the worm wheel 20. If the worm wheel 20 experiences a torque (referred to herein as “back-drive torque"), teeth of the worm wheel press against the teeth of the worm 22 and, due to the difference in angles between the teeth on the worm wheel 20 and worm 22, the driven worm wheel 20 moves the worm 22 laterally along its axis, instead of rotating. [0068] This back-drive torque provides lock up for the refractor 10 to prevent rapid extraction of the seat belt 12 such as during an emergency.
  • back-drive torque provides lock up for the refractor 10 to prevent rapid extraction of the seat belt 12 such as during an emergency.
  • the seat belt 12 is wound around the spool 14, and the worm 22 engages the worm wheel 20 such that emergency extraction introduces a counter-clockwise torque on the worm wheel 20.
  • the seat belt 12, spool 14, worm 22 and worm wheel 20 may be arranged such that emergency extraction introduces a clockwise torque on the worm wheel 20.
  • a back-drive torque is introduced when the seat belt 12 is extracted by an external force.
  • the worm wheel 20 experiences the back-drive torque
  • the worm wheel 20 slides the worm 22 and drive shaft 24 towards the first connector 28.
  • the drive shaft 24 passes through the first connector 28 and the worm 22 contacts and compresses the spring 34 against the first connector 28.
  • a spring 34 may not be used and the worm 22 may contact the first connector 28 directly.
  • the first connector 28 serves as a stop 36.
  • the spring 34 When the spring 34 is compressed, the first connector 28 prevents further lateral movement of the worm 22 and drive shaft 24.
  • the worm 22 abuts the compressed spring 34 and stop 36, the worm 22 preferably maintains engagement with the worm wheel 20.
  • the refractor 10 is locked to prevent further seat belt 12 extraction.
  • the back-drive force rotates the worm wheel 20 a minimal distance in a counter-clockwise direction before the spool 14 is locked. The spool 14 remains locked so long as the back-drive torque is greater than the bias force of the spring 34.
  • the spring 34 moves the worm 22 and drive shaft 24 back to a normal operating position with respect to the worm wheel 20 and the motor 32 is activated to refract or extract the seat belt 12 as needed.
  • the retractor 10 is unlocked.
  • extraction force refers to a force which causes seat belt 12 extraction at a rate greater than the extraction rate caused by regular use of the seat belt 12. Generally, regular extraction forces are minimal and do not cause the worm 22 and drive shaft 24 to move laterally before the retractor 10 responds by driving the worm 22 in the direction to pay out the seat belt 12.
  • the extraction force occurs when a vehicle experiences an accident or extreme conditions leading to a possible accident such as panic braking, swerving, or the like.
  • the retractor 10 includes a switch 38 in electrical communication with the electrical circuit (discussed below) which powers and operates the motor 32 of the refractor 10.
  • the switch 38 provides an additional safety feature to ensure that when spool 14 is locked, the motor 32 can not be activated in the direction of seat belt 12 extraction.
  • the switch 38 may also serve as a sensor to detect when the retractor 10 has been locked in an emergency.
  • the switch 38 is secured to the first connector 28 such that as the drive shaft 24 slides through a passage (not shown) in the connector 28, the drive shaft 24 activates the switch 38.
  • the switch 38 may be a microswitch which is closed under normal conditions and opened by the lateral movement of the drive shaft 24.
  • the circuit is provided with an operational flow of power for activating the motor 32.
  • the switch 38 is open, the power flow is interrupted such that the motor 32 can not be activated to pay out the seat belt 12 and defeat the locking of the spool 14.
  • the spring 34 slides the worm 22 and drive shaft 24 back into normal operational position which causes the drive shaft 24 to close the switch 38 and restore power flow in the circuit to the motor 32.
  • the electric seat belt retractor 10 should pay out and retract the seat belt 12 based on the actions of the occupant. These actions may be determined by sensing the amount of tension present in the portion of the seat belt 12 which extends from the retractor 10. For example, as an occupant buckles a latch plate to a buckle, the tension in the seat belt 12 increases. Once the seat belt 12 is buckled or unbuckled, the tension decreases. In addition, as an occupant moves their upper torso while buckled in the seat belt 12, the tension in the seat belt changes once again.
  • the retractor 10 includes a tension sensor 40.
  • the tension sensor 40 measures tension in the seat belt 12 between the refractor 10 and the other end of the belt 12. Based on the tension, the refractor 10 may be controlled to retract or extract the seat belt 12 as necessary.
  • the tension sensor 40 is connected to the retractor frame 18.
  • the tension sensor 40 may be positioned at other locations along the length of the seat belt 12 extending from the spool 14 of the retractor 10.
  • the retractor frame 18 comprises a frame which is anchored to a vehicle. One side of the retractor frame 18 comprises the belt opening 42. The belt opening 42 is where the seat belt 12 extends from the frame 18.
  • the seat belt 12 is extracted and retracted from the spool 14 through the belt opening 42.
  • the belt opening 42 may be of various sizes.
  • the belt opening 42 may comprise one whole side of the frame 18.
  • the belt opening 42 may be of a minimal size that still allows the seat belt 12 to be extracted and refracted.
  • the tension sensor 40 serves as a web guide that orients and untwists the seat belt 12 before the seat belt 12 is wound around the spool 14.
  • the tension sensor 40 may serve as a door that opens and closes the belt opening 42 in response to the level of tension in the portion of the seat belt 12 extending from the retractor 10.
  • the tension sensor 40 includes an arm 44 which extends over the belt opening 42.
  • the arm 44 is sized to substantially cover the belt opening 42.
  • the arm 44 is pivotally connected to the refractor frame 18 at one side of the belt opening 42.
  • the arm 44 may be connected by various pivoting mechanisms.
  • the pivot 46 may comprise an axle 47 (Seen in Figure 5) which passes through the arm 44 and is secured to opposite sides of the frame 18.
  • the pivot 46 allows the arm 44 to pivot through an angle 48 measured between the arm 44 and a reference line 50 indicated generally by the belt opening 42.
  • the angle 48 is about zero degrees.
  • the pivot 46 allows the arm 44 to pivot freely to form an angle 48 between about zero degrees and about ninety degrees.
  • the angle 48 may range between about zero degrees and about one- hundred and eighty degrees. Of course different configurations may allow for still different angle ranges.
  • the unconnected end of the arm 44 includes a webbing passage 52.
  • the extended portion of the seat belt 12 is threaded through the webbing passage 52.
  • the seat belt 12 is wound on the spool 14 such that the seat belt 12 exits the spool 14 and extends from one end of the arm 44 to the other end, the webbing passage 52.
  • tension between where the seat belt 12 winds around the spool 14 and a portion of the seat belt 12 which is threaded through the webbing passage 52 causes the arm 44 to pivot about the pivot 46.
  • the arm 44 is extended away from the belt opening 42, creating an angle 48 of about ninety degrees.
  • the arm 44 When very low or minimal tension is present, the arm 44 substantially covers the belt opening 42 and creates an angle of about zero degrees.
  • the arm 44 may include a torsional spring 53 (shown in Figure 5) which is loaded when tension in the seat belt 12 extends the arm 44.
  • the torsional spring 53 may bias the arm 44 towards the retractor frame 18 when the seat belt tension is minimal.
  • the tension sensor 40 is capable of controlling the retractor 10 to activate and/or deactivate the motor 32 to retract or extract the seat belt 12 as necessary.
  • the tension sensor 40 is in electrical communication with an electrical circuit (See Figure 4) for powering and controlling the retractor 10. Components for the electrical circuit may be secured to a circuit board 54 connected to the refractor frame 18.
  • the tension sensor 40 measures the tension in the seat belt 12 by measuring the position of the arm 44 with respect to the belt opening 42 and translating this position into voltage which is delivered to the motor 32.
  • a potentiometer 55 may be used to perform the translations.
  • an axle of a rotary potentiometer 55 may be coupled to the pivot 46 of the tension sensor 40 such that movement of the arm 44 moves a wiper in the potentiometer 55 to vary the level of power provided to the circuit.
  • the potentiometer 55 varies the level and polarity of voltage across the potentiometer 55 made available to the circuit.
  • the sensor 40 need not be an angular sensor, but may rather be a linear sensor or some other type of sensors.
  • an element that translates or moves in a manner different from angular or linear motion may be used.
  • the senor 40 need not have any moving elements, but may utilize a sensor that detects relative position, motion, or tension through the use of optical, magnetic, or other intangible effects.
  • a wide variety of sensors including Hall effect probes, linear variable displacement transducers (LNDT's), magnetic readers, optical readers, piezoelectric or resistance-based load cells, and the like may be used.
  • LNDT's linear variable displacement transducers
  • magnetic readers magnetic readers
  • optical readers piezoelectric or resistance-based load cells, and the like
  • load cells piezoelectric or resistance-based load cells, and the like
  • the potentiometer 55 provides a positive voltage which activates the motor 32 to turn the worm 22 in the direction to pay out the seat belt 12.
  • the voltage level increases as the arm 44 moves from about a forty-five degree angle 48 to about a ninety degree angle 48.
  • the motor 32 speeds up proportionally until the maximum pay out speed for the motor 32 is reached.
  • the arm 44 moves towards the retractor frame 18.
  • the arm 44 may be moved by gravity or a torsional spring 53 (See Figure 5).
  • the potentiometer 55 provides a negative voltage which activates the motor 32 to turn the worm 22 in the direction to retract the seat belt 12 onto the spool 14.
  • the potentiometer 55 gradually provides more negative voltage as the angle 48 approaches zero, until the motor 32 reaches a maximum retraction speed.
  • any slack introduced in the seat belt 12 by, for example, the occupant first buckling the seat belt 12 or moving his her upper torso is automatically removed based solely on the tension detected by the tension sensor 40.
  • the tension sensor 40 may provide the activation voltages or no voltage when the arm 44 forms other angles 48 in response to tension in the seat belt 12. For example, no voltage may be provided by the tension sensor 40 when a sixty degree angle 48 is formed.
  • the tension which raises the ami 44 to about forty-five degrees is tension which may be unnoticeable to the occupant.
  • the amount of tension felt in the seat belt 12 when the arm 44 is at forty-five degrees is affected by the effect of gravity on the arm 44 and any bias provided by a torsional spring 53 on the arm 44 at the pivot 46. Therefore, the amount of tension in the seat belt 12 when the retractor 10 is deactivated may be adjusted by varying the bias of the torsional spring 53, weight of the ami 44, or orientation of the potentiometer 55 with respect to the pivot 46.
  • Figure 3 A illustrates a side view of one embodiment of a gear drive system 56 for the present invention.
  • the basic operation of the gear drive system 56 is described above in relation to Figure 1.
  • Figure 3 A illustrates the gear drive system 56 in which back-drive torque may be introduced by rapid extraction of the seat belt 12.
  • the gear drive system 56 may be used in other applications which introduce a back-drive torque, for example to determine when a powered system is overloaded.
  • the gear drive system 56 includes a worm wheel 20, drive shaft 24, motor 32 and worm 22 fixed to the drive shaft 24.
  • the drive shaft 24 is secured by one or more connectors 28, 30, such as pillow blocks, which allow rotational and axial movement of the drive shaft 24.
  • the connectors 28, 30 are connected to a base 31 such as a retractor frame 18.
  • the worm wheel 20 is coupled to a load 58.
  • the load 58 is the rotatable axle 15 of a seat belt retractor spool 14. Operation of the gear drive system 56 in response to a back-drive torque (indicated by arrow 59) introduced by extraction of the seat belt 12 is discussed above.
  • different loads 58 may be coupled to the worm wheel 20.
  • a rack (not shown) for a power window system of a vehicle may be coupled to the worm wheel 20.
  • An overload condition refers to a condition in which the load 58 is impeded or abno ⁇ nally accelerated in some manner contrary to no ⁇ nal movement. This overload condition creates a back-drive torque 59 in the worm wheel 20.
  • the worm 22 screws past the worm wheel 20 and moves the drive shaft 24 laterally. Lateral movement of the drive shaft 24 may be controlled by a compression spring 34.
  • the laterally moving drive shaft 24 may be used to stop the system.
  • the sliding drive shaft 24 may activate a switch 38 to interrupt power to the motor 32 and deactivate the system 56.
  • the switch 38 may act as a sensor 60 for detecting an overload condition for the system 56.
  • FIG. 3A the gear drive system 56 is illustrated in an overload condition.
  • the drive shaft 24 has moved axially in response to a back-drive torque created in the worm wheel 20.
  • the switch 38 has been activated and power to the motor 32 is interrupted stopping rotation of the drive shaft 24.
  • FIG. 3B if the overload condition is resolved, by reducing or removing the back-drive torque 59, the switch 38 is deactivated to restore power to the motor 32. The wonn 22 and drive shaft 24 are returned to a normal position. The system 56 may then continue normal operation under control of the tension sensor 40.
  • FIG. 4 a functional diagram of an electrical circuit 62 for operating an electric retractor 10 is illustrated.
  • the circuit 62 may comprise a variety of configurations. For example, the components may be connected in series, parallel or some combination of these.
  • the circuit 62 may also include various electrical components which are well known and have been omitted for clarity.
  • the circuit 62 includes the switch 38, the motor 32 and the tension sensor 40.
  • the tension sensor 40 is electrically coupled to a power source 64.
  • the power source 64 is the same power source for the electrical system of a vehicle.
  • the tension sensor 40 includes a potentiometer 55 which regulates the magnitude and polarity of the voltage provided to the motor 32 based on tension in the seat belt 12. If tension in the seat belt 12 causes the retractor 10 to lock, the drive shaft 24 activates the switch 38 which opens the circuit 62 and stops power flow to the motor 32. If the tension is released and the drive shaft 24 returns to within normal ranges, the switch 38 is closed and power is restored to the motor 32.
  • the electric refractor 10 comprises an automatic locking system 66.
  • the automatic locking system 66 is a system which retracts the seat belt 12 onto the spool 14 and does not permit the seat belt 12 to be extracted until the automatic locking system 66 is deactivated. With the automatic locking system 66 activated, an occupant is not able to extract additional seat belt webbing.
  • the automatic locking systems 66 may be used when fastening child safety seats using a regular seat belt system (lap or shoulder).
  • the automatic locking system 66 is activated when a predetermined amount of seat belt webbing 12 has been extracted from the retractor 10. This predetermined amount may be referred to as an activation threshold.
  • the automatic locking system 66 is deactivated when a predetermined amount (a deactivation threshold) of seat belt webbing 12 has been refracted onto the spool 14 of the retractor 10.
  • the activation threshold is defined as substantially all of the seat belt 12 being extracted and the deactivation threshold is defined as substantially all of the seat belt 12 being retracted.
  • these thresholds may vary.
  • the automatic locking system 66 includes a sensor 68 and counting module 70 which cooperate to determine when the activation and deactivation thresholds have been reached.
  • the sensor 68 may be a rotational sensor 68 that detects revolutions of the spool 14. For each rotation, a signal is provided to the counting module 70.
  • the counting module 70 includes an analog circuit that increments a count, for example, through the use of incrementally variable capacitance or resistance, for each rotation in the direction of seat belt extraction and decrements the count for each rotation in the direction of seat belt retractions. When the count reaches or exceeds a number corresponding to the activation threshold, the counting module 70 activates the automatic locking system 66. When the count reaches or falls below a number corresponding to the deactivation threshold, the counting module 70 deactivates the automatic locking system 66.
  • the automatic locking system 66 includes well known electrical components for overriding the normal operation of the tension sensor 40.
  • the automatic locking system 66 then provides power to the motor 32 for retracting the seat belt 12 regardless of the level of tension measured by the tension sensor 40. hi certain embodiments, high tension measured by the tension sensor 40 may be used to deactivate the motor 32 and stop retracting the seat belt 12. While activated, the automatic locking system 66 prevents powering of the motor 32 for extraction of the seat belt 12.
  • FIG. 5 illustrates one embodiment of an automatic locking system 66 for use with the present invention.
  • the rotational sensor 68 comprises an optical sensor 68 which is activated by a reflector 72 connected to a wheel 74.
  • various mechanical sensors may be used to detect revolutions of the spool 14.
  • the wheel 74 is connected to the spool 14 such that rotation of the spool 14 rotates the wheel 74.
  • the optical sensor 68 may include a pair of lasers, or sub-sensors (not shown), which allow the direction of rotation to be determined by identifying which sub-sensor was activated first. Activation of the sensor 68 sends a signal to the counting module 70 which maintains a count as described above.
  • a seat belt retractor 10 provides pre-crash pretensioning and pretensioning in response to sensors which determine that an accident is very likely to occur or that an accident has occurred. Pretensioning is the intentional retraction of the seat belt 12 into the retractor 10, pre-crash pretensioning, in anticipation of an accident. Generally, pre- crash pretensioning occurs a few seconds prior to an accident. Pre-crash pretensioning is activated by one or more vehicle dynamics.
  • a vehicle dynamic is a measurement of one or more characteristics of the operation of a vehicle. For example, vehicle dynamics may include measurements such as sudden braking, loss of traction, spinning of the vehicle, dramatic changes in the pitch and/or yaw of the vehicle, and other such dynamics of a vehicle. The vehicle dynamics may be affected by the speed of the vehicle, condition of the road, and the like.
  • Pre-crash pretensioning refracts the seat belt 12 onto the spool 14 to reduce the amount of slack in the seat belt 12. Minimal slack improves the ability of the seat belt 12 to protect the occupant in an accident.
  • pre-crash pretensioning alerts the occupant that the vehicle dynamics indicate an accident may occur. Such an alert may allow the occupant to take evasive actions such as steering corrections or braking to avoid an accident.
  • the seat belt retractor 10 should extract a portion of the seat belt 12 to relieve the tension in the seat belt 12 introduced by the pre-crash pretensioning.
  • Accident pretensioning is also an intentional rapid refraction of the seat belt 12 into the refractor 10.
  • crash pretensioning is activated when a crash sensor is activated.
  • Accident pretensioning occurs milliseconds into the accident.
  • the purpose of crash pretensioning is to remove any excess slack and to assist in positioning the occupant in the seat such that other safety systems can effectively protect the occupant.
  • activating the worm 22 in the direction to retract the seat belt 12 may be done with such a high torque that the tension introduced into the seat belt 12 can re-position the upper torso of an occupant against the seat.
  • Accident pretensioning may or may not be reversible once the accident event ends.
  • FIG. 6 a functional block diagram illustrates a circuit 76 for controlling the electric retractor 10 in an emergency situation to provide pre-crash pretensioning and crash pretensioning.
  • the circuit 76 includes the power source 64, motor 32, switch 38, and tension sensor 40 discussed above.
  • the circuit 76 includes an emergency control system 78.
  • the emergency control system 78 may be very simple or complex, h certain embodiments, the emergency control system 78 may be analog and may be integrated with the circuit 76 and with other safety systems of a vehicle such as airbag systems. Alternatively, the emergency control system 78 may include a simple logic module.
  • the emergency control system 78 overrides the tension sensor 40 and activates the motor 32 to retract the seat .belt 12 and provide pre-crash pretensiomng or pretensioning based on inputs from vehicle dynamics sensors 80.
  • the emergency control system 78 is in electrical communication with a plurality of vehicle dynamics sensors 80, designated 80a-80c, which may be positioned throughout a vehicle.
  • the vehicle dynamics sensors 80 may be integrated with the emergency control system 78.
  • each sensor 80 measures a single vehicle dynamic.
  • one sensor 80 may comprise an accelerometer for measuring rapid deceleration.
  • the vehicle dynamics sensors 80 may send signals continuously or when the dynamic is outside an acceptable threshold range.
  • the emergency control system 78 receives input from a crash sensor 82.
  • a crash sensor 82 is activated when the vehicle experiences an impact during an accident. Of course, other events in the initial stages of an accident may also trigger a crash sensor 82.
  • the emergency control system 78 receives inputs from the sensors 80 and or one or more crash sensors 82. Based on these inputs and an algorithm, the emergency control system 78 determines whether pre-crash pretensioning or crash pretensioning should be activated.
  • the vehicle dynamics sensors 80 send signals to the emergency control system 78 and the crash sensor 82 is not activated, pre-crash pretensioning is activated. If the vehicle dynamics sensors 80 stop sending signals or send signals that vehicle dynamics have returned to normal and the crash sensor 82 is not activated, the emergency control system 78 may stop overriding the tension sensor 40. Then, because the pre-crash pretensioning put tension in the seat belt 12, the tension sensor 40 activates the motor 32 to extract the seat belt 12 until the tension sensor 40 detects normal tension in the seat belt 12. h this manner, the pre-crash pretensioning is reversible.
  • the emergency control system 78 overrides the tension sensor 40 and activates the motor 32 to provide crash pretensioning.
  • the emergency control system 78 may overpower the motor 32 such that a maximum retraction torque available from the motor 32 is used to retract the spool 14. Overpowering the motor 32 may damage the motor 32. However, safety of the occupant is most important and the motor 32 can be repaired or replaced if necessary.
  • the emergency control system 78 may provide pre-crash pretensioning initially followed by crash pretensioning once a crash sensor 82 is activated.
  • pre-crash pretensioning and crash pretensiomng may be provided in stages.
  • the motor 32 allows for pre-crash pretensioning and crash pretensioning without expensive pyrotechnic pretensioners.
  • the electric refractor 10 of the present invention allows for reversible pre-crash pretensioning in the event that an accident is avoided.
  • the present invention provides an electric retractor 10 for powered extraction and retraction of a seat belt 12.
  • the retractor 10 provides powered extraction and refraction using a simple worm gear drive system 56 (See Figures 3A, 3B) which locks in response to a back-drive torque introduced by extraction forces due to rapid extraction of the seat belt 12.
  • Powered extraction and refraction is controlled by a tension sensor 40 which proportionally activates the motor 32 to retract or extract the seat belt 12 based on the tension present in the seat belt 12.
  • the refractor 10 provides a relatively constant degree of tension on the seat belt while permitting relatively free occupant motion.
  • the retractor 10 provides advanced features such as an automatic locking system 66, reversible pre-crash pretensioning, and crash pretensioning using electronics and emergency control systems 78.
  • the retractor 10 provides the advanced features without pyrotechnic components and with fewer mechanical components than conventional refractors.
  • the present invention provides enhanced structures and methods by which the tension in a flexible member may be accurately controlled. These enhanced structures and methods are applicable over a wide range of applications. [00119] SECTION ⁇
  • the webbing sensor 40 includes a base 31 for securing the webbing sensor 40 in relation to the movable seat belt webbing or flexible member 12.
  • the base 31 may be a rigid rectangular member, as illustrated.
  • the base 31 may be a structure of any shape which anchors the webbing sensor 40.
  • the seat belt webbing sensor 40 includes a rigid member 44 such as an arm 44.
  • the arm 44 is pivotally connected to the base 31 by a pivot 46.
  • the pivot 46 allows the arm 44 to pivot through at least ninety degrees with respect to the base 31.
  • the pivot 46 may comprise an axle (not shown) which passes through the base 31 and the arm 44.
  • the arm 44 is a rigid, planar, rectangular member that includes a pivot end 90 and a contact end 92.
  • the arm 44 may be in various configurations so long as the arm 44 is rigid or semi-rigid such that movement and changes in tension in the seat belt webbing 12 cause the arm 44 to pivot.
  • the pivot 46 connects the pivot end 90 to the base 31.
  • the contact end 92 pivots freely about the pivot 46.
  • the contact end 92 directly contacts the seat belt webbing 12.
  • a keeper 94 is connected to, and extends from, the contact end 92.
  • the keeper 94 includes a hole, or passage 52, through which the webbing 12 passes.
  • the keeper 94 allows the arm 44 to maintain contact with the webbing 12.
  • the arm 44 may include a passage (not shown) similar to the passage 52 near the contact end 92 through which the webbing 12 passes, h yet another alternative, the arm 44 may be configured such that the contact end 92 of the arm 44 directly contacts the seat belt webbing 12 without passage of the webbing 12 through the contact end 92.
  • the arm 44 communicates with the seat belt webbing 12 such that movement of the webbing 12 causes the arm 44 to pivot.
  • the arm 44 is sized such that the arm 44, or keeper 94, maintains contact with the webbing 12 as the contour of the webbing 12 changes.
  • the contour of the webbing 12 changes in response to changes in the tension in the webbing 12.
  • the arm 44 is biased towards the seat belt webbing 12.
  • the bias ensures that the arm 44 maintains contact with the webbing 12.
  • a spring 53 (See Figure 8) incorporated with the pivot 46 biases the arm 44 toward the seat belt webbing 12.
  • the bias may be provided by gravity acting on the arm 44.
  • the seat belt webbing sensor 40 contacts a portion of the seat belt webbing 12 between the two ends (not shown) of the webbing 12. Generally, the two ends of the webbing 12 are secured in some fashion.
  • the positioning of the pivot 46 and the length of the arm 44 may affect the sensitivity of the seat belt webbing sensor 40 to movement of the webbing 12.
  • the pivot 46 is positioned in the base 31 in close proximity to the webbing 12.
  • the pivot 46 may allow the arm 44 to move between a position substantially parallel to the webbing 12 and a position substantially perpendicular to the webbing 12.
  • the webbing 12 passes in close proximity to the pivot 46 and traverses the length of the arm 44 before contacting the arm 44, for example, by passing through the passage 52 of the keeper 94.
  • the arm 44 pivots in response.
  • the rate at which the arm 44 pivots and/or the amount of change in the position of the arm 44 may be used to measure forces acting on the seat belt webbing 12.
  • the seat belt webbing sensor 40 includes a sensor 96 coupled to the arm 44 to detect movement of the arm 44 relative to the base 31.
  • a variety of sensors 96 may be used.
  • the sensor 96 may measure a change the angular position of the arm 44 between a first position and a second position.
  • the sensor 96 may measure the velocity or acceleration of the arm 44 from a first position to a second position.
  • Angular deflection or motion of the arm may be measured with respect to almost any reference line.
  • the sensor 96 may also be digital or analog.
  • a feature designed to translate or move in a different manner with respect to the base 31 may be used in place of the ami 44.
  • a sensor (not shown) that correspondingly measures linear or other motion may then be used in place of the rotary detection provided by the sensor 96.
  • the sensor 96 provides a signal that corresponds to the movement of the arm 44. For example, if the sensor 96 detects the angular motion of the arm 44, when the angle changes, a signal is provided by the sensor 96 to indicate the change. Alternatively, if the sensor 96 is designed to simply indicate a predetermined position for the arm 44, the signal may not be provided until the arm 44 is in the predetermined position.
  • the signal may be an electrical signal, an optical signal, a digital signal, a change in an electrical signal such as a drop or rise in voltage, or the like.
  • the nature of the signal may be adapted to suit different applications in which a seat belt webbing sensor is incorporated.
  • the signal is an analog signal capable of being amplified and used for motor control.
  • FIG 8 illustrates a seat belt webbing sensor 40 integrated with an electric seat belt refractor 10.
  • the webbing sensor 40 is integrated with a web guide 98 for the retractor 10.
  • the web guide 98 untwists and aligns the webbing 12 with a spool 14 of the refractor 10 such that the webbing 12 may be properly extracted and refracted.
  • the seat belt webbing sensor 40 serves as a tension sensor 40 for detecting changes in tension in the webbing 12 extending from the spool 14.
  • the retractor frame 18 provides a base 31 for the sensor 40.
  • the retractor 10 includes an electric motor 32 coupled to the spool 14 for rotating the spool 14 in either direction about an axis 16.
  • the motor 32 may be a direct current (DC) motor.
  • the electric motor 32 may be coupled to the spool 14 using a gear system 56, which may be configured in a variety of ways.
  • the electric motor 32 rotates the spool 14 to pay out and retract the webbing 12 as needed.
  • one end of the webbing 12 is anchored to the vehicle outside the retractor 10.
  • the remainder of the webbing 12 passes tlirough a latch plate or buckle and a D-ring before being wound around the spool 14.
  • the seat belt webbing sensor 40 may control the operation of the electric motor 32 via movement of the web guide 98. For example, if tension in the seat belt webbing 12 causes the web guide 98 to extend away from the retractor 10, the webbing sensor 40 activates the motor 32 to pay out the webbing 12. Similarly, if the tension in the webbing 12 causes the web guide 98 to pivot toward the retractor 10, the webbing sensor 40 activates the motor 32 to retract the webbing 12.
  • the refractor 10 may be used for either the driver's side or the passenger's side of the vehicle. Due to the use of the webbing sensor 40, the retractor 10 maintains about the same level of tension to seat belt webbing 12 in any location within a vehicle. If desired, the retractor 10 may also be used with certain types of lap belts.
  • Figure 9 illustrates a side view of a feedback control system 100 which includes the seat belt webbing sensor 40, as incorporated in the electric seat belt retractor 10 illustrated in Figure 8. No ⁇ rial operation of the electric retractor 10 is controlled by the webbing sensor 40. During an emergency, the webbing sensor 40 may be overridden to provide emergency locking of the retractor 10.
  • the webbing sensor 40 may be connected to the retractor frame 18 (the base 31) near a belt opening 42.
  • the belt opening 42 is the side of the refractor frame 18 where the webbing 12 enters the retractor 10.
  • the base 31 may run substantially perpendicular (as indicated by reference line 50) to the webbing 12 exiting the retractor 10.
  • the seat belt webbing sensor 40 may detect tension in the webbing 12 using an angular sensor 96 which is mechanically coupled to the ami 44.
  • the arm 44 pivots in response to changes in tension in the webbing 12.
  • the angular sensor 96 is an analog sensor that provides a signal that varies in magnitude based on the position of the arm 44 relative to the base 31.
  • a different signal may be provided based on the position of the arm 44.
  • the signal provided directly corresponds to the position of the arm 44.
  • sensors 96 may be used and the sub-components and communication between the sensor 96 and the arm 44 may vary.
  • the sensor 96 may be connected to the arm 44, the pivot 46, or the base 31.
  • the sensor 96 may measure movement of the arm 44 without a direct connection to the arm 44.
  • the sensor 96 may detect changes in a magnetic field, refracted light rays, or the like.
  • the sensor 96 may measure acceleration of the arm 44 about the pivot 46 between a first position and a second position.
  • the angle 48 generally represents the angle between the arm 44 and the base 31, identified generally by the reference line 50.
  • the angular sensor 96 detects movement of the arm 44 between a first position approximately parallel with the base 31 (and the reference line 50), to a second position approximately parallel to the webbing 12 and perpendicular to the reference line 50.
  • the angular sensor 96 need not directly measure the angle 48 between the base 31 and the arm 44.
  • alternative webbing sensors may use a sensor that does directly measure such an angle 48.
  • exemplary magnitudes and ranges of the angle 48 may be referred to for illustration and clarity. Those of skill in the art understand that the webbing sensor 40 may be configured to use a variety of different magnitudes and/or angle ranges of the angle 48.
  • the sensor 96 may comprise a potentiometer 55 coupled to the arm 44.
  • the potentiometer 55 may be coupled to the pivot 46.
  • the potentiometer 55 is a rotary linear taper potentiometer.
  • An axle (not shown) of the potentiometer 55 may be connected to the pivot 46. Movement of the arm 44 moves a wiper (not shown) within the potentiometer 55 to vary a voltage provided to the motor 32.
  • the potentiometer 55 may be in electrical communication with a servo amplifier 102.
  • the servo amplifier 102 may be a voltage amplifier that amplifies the voltage output of the potentiometer prior to transmission of the voltage to the motor 32. Thus, the servo amplifier 102 provides a voltage to the motor 32 that corresponds to a signal from the potentiometer 55.
  • the potentiometer 55 provides a linear gradation in output voltage as the arm 44 pivots through an angle 48 of between about zero degrees to about ninety degrees. At one point within the aforementioned angular range, the output voltage may cross a zero point to provide a change in output voltage potential. Voltages of one polarity may be retraction voltages that activate the motor 32 to retract the webbing 12, and voltages of the opposite polarity may be extraction voltages that activate the motor 32 to pay out the webbing 12.
  • the point at which the output voltage is zero may correspond to an angle 48 of about forty-five degrees.
  • the motor 32 is deactivated when the angle 48 is about forty-five degrees.
  • a certain amount of tension (referred to herein as the predetermined tension) is present in the webbing 12 to cause the arm 44 to maintain an angle 48 of about forty-five degrees.
  • the angle 48 is greater than or less than forty-five degrees, the motor 32 receives voltage and operates accordingly.
  • retraction voltages may be provided for an angle 48 between about zero and twenty degrees and extraction voltages may be provided for an angle 48 between about thirty-five and sixty degrees.
  • predetermined tension is an amount of tension in the webbing 12 which allows a seat belt system to properly protect an occupant without causing occupant discomfort.
  • the predetermined tension is determined by the position of the pivot 46, the length of the arm 44, and the design of the potentiometer 55.
  • a torsional spring 53 (See Figure 8) in communication with the arm 44 biases the arm 44 towards the belt opening 42.
  • the bias of the spring 53 may also affect the magnitude of the predetermined tension.
  • the predetermined tension may be between about two and about four Newtons.
  • the arm 44 extends over the belt opening 42 because minimal tension is in the webbing 12.
  • the sensor 96 detects that the arm 44 is between about zero and about forty-five degrees, h response, the sensor 96 provides a retraction voltage to the servo amplifier 102.
  • the servo amplifier 102 may be a conventional bridge amplifier that provides an amplified voltage in response to an input voltage provided by the sensor 96.
  • the amplifier 102 takes the input voltage and provides a corresponding output voltage of the same polarity but with a higher magnitude.
  • the input voltage is amplified to the level needed to activate the motor 32.
  • the voltage is amplified by a factor of ten.
  • Output voltage of one polarity for example, positive, activates the motor 32 to rotate the spool 14 in a direction for extraction of the webbing 12.
  • output voltages in the opposite polarity activate the motor 32 to rotate the spool 14 in a direction for webbing 12 refraction.
  • the servo amplifier 102 hi response to a retraction voltage from the sensor 96, the servo amplifier 102 provides an amplified refraction voltage to the motor 32.
  • the voltage change activates the motor 32 to refract the webbing 12. If the seat belt webbing 12 is not in use, retraction of the webbing 12 by the motor 32 causes the arm 44 to extend above the belt opening 42 until the arm 44 forms about a forty-five degree angle 48. As the arm 44 approaches forty-five degrees, the sensor 96 may gradually provide less retraction voltage. As mentioned above, when the arm 44 is at about forty-five degrees, substantially no voltage is provided by the sensor 96, and thus, the motor 32 is deactivated until a change in the tension of the webbing 12 occurs.
  • the sensor 96 provides an extraction voltage to the servo amplifier 102.
  • the servo amplifier 102 provides the corresponding output voltage to activate the motor 32 to rotate the spool 14 to extract webbing 12.
  • the tension decreases, i response, the arm 44 pivots to bring the angle 48 back toward about forty-five degrees.
  • the extraction voltage and corresponding output voltage also gradually decrease. A gradual change in the voltage causes the motor 32 to gradually slow until it stops when the angle 48 reaches about forty-five degrees.
  • FIGs 8 and 9 illustrate the seat belt webbing sensor 40 integrated with the seat belt retractor 10.
  • the seat belt webbing sensor 40 may be disposed separate from the seat belt refractor 10.
  • the seat belt webbing sensor 40 may be used to control other systems besides, or in addition to, the seat belt retractor 10. For example, tension, acceleration, and/or other movement of the webbing 12 may be monitored by the flexible member sensor 40 for activation of various vehicular safety systems such as airbags.
  • Figure 10 illustrates an embodiment of the seat belt webbing sensor 40 having a different orientation and/or configuration.
  • the webbing sensor 40 may be secured to a vehicle pillar 104 (B-pillar, C-pillar, or the like) via a base 31 screwed, welded or otherwise secured to the pillar 104.
  • the base 31 may comprise a securing member (not shown) integrated with the pivot 46.
  • the positions of the arm 44 which activate a retractor 10 to extract and retract the webbing 12, may be different because of the position and orientation of the sensor 40.
  • the pivot 46 may allow the arm 44 to pivot tlirough one-hundred and eighty degrees, as indicated by an arrow 106.
  • a spring 53 (See Figure 8) may bias the arm 44 to urge the arm 44 to rotate generally upward, in the a direction opposite to that of the arrow 106.
  • the predetermined tension may be tension which allows the spring 53 to pivot the arm 44 to about an eighty-five degree angle 48.
  • the range of angles which cause the sensor 40 to activate the refractor 10 for extraction and retraction may be, respectively, between about eighty-five degrees and about one-hundred and eighty degrees, and between about eighty-five degrees and about zero degrees. As mentioned above, different angle ranges may be used within the scope of the present invention.
  • Conventional motion control systems include a controller which sends control signals to the motor to achieve a desired motion. The motor is coupled to a load such that activation of the motor actuates the load.
  • a conventional motion control system measures the operation of the motor to infer what adjustments need to be made to obtain the desired load motion. New signals are sent to the motor to provide correction.
  • correction methods are typically somewhat inaccurate, h the course of adjustment, the load may move in a manner that overshoots or undershoots the desired adjustment.
  • many motor adjustments may be required to provide the desired load motion, thereby requiring further adjustment and adding to the time required to obtain the desired load motion characteristics.
  • the present invention provides feedback control systems that more accurately obtain the desired load motion.
  • the feedback control system 100 illustrates the operation of a sensor according to the invention, such as the seat belt webbing sensor 40 described previously.
  • the feedback control system 100 includes a load feedback control loop 110.
  • a feedback sensor 112 measures and reports movements of the load 114, rather than dynamics of the motor.
  • a load feedback control loop 110 uses the load motion infomiation to substantially eliminate motion control errors. Motor characteristics such as angular position, velocity, and acceleration need not even be measured.
  • the feedback control system 100 includes a controller 116, a motor 118, a load 114, and a feedback sensor 112.
  • the controller 116 and motor 118 may be of various conventional designs.
  • the load 114 may be almost any object which is to be moved by the feedback control system 100.
  • the feedback sensor 112 may be one of various sensors designed to measure one or more aspects of movement of the load 114 such as position, velocity, or the like.
  • the feedback sensor 112 may be in direct communication with the load 114 such that subtle changes in dynamics of the load 114 may be detected and reported.
  • the feedback sensor 112 and the controller 116 for the system 100 may be integrated into a single unit. Alternatively, the controller 116 and feedback sensor 112 may be separate, independent components.
  • the load feedback control loop 110 comprises a control flow from the controller 116 to the motor 118, which actuates the load 114, plus the feedback of information about movement of the load 114, provided by the feedback sensor 112 to the controller 116.
  • the feedback information allows the controller 116 to signal the motor 118 to provide precise and accurate movement of the load 114.
  • the feedback sensor 112 comprises an analog sensor which provides a variable signal in response to movement of the load 114.
  • the feedback control system 100 includes a driver 120 that receives the signal provided by the controller 116.
  • the driver 120 may change the signal in order to activate the motor 118.
  • the driver 120 boosts the strength of the control signal by increasing the current and/or voltage.
  • the driver 120 may comprise a servo amplifier that simply increases the magnitude of the signal from the controller 116.
  • the driver 120 may replace the control signal with a corresponding activation signal for the motor 118.
  • the feedback control system 100 and load feedback control loop 110 may be implemented using an electric seat belt retractor 10 that includes the seat belt webbing sensor 40.
  • the seat belt webbing 12 may comprise the load 114.
  • the motor 32 of the electric seat belt retractor 10 may comprise the motor 118.
  • the servo amplifier 102 may comprise the driver 120.
  • the webbing sensor 40 may comprise both the feedback sensor 112 and the controller 116.
  • the electric seat belt retractor 10 may initially be in a stable state, meaning a predetermined tension is present in the webbing 12 and the motor 32 is deactivated. If the webbing 12 is pulled or released, changing the tension, the webbing sensor 40 detects the change almost instantaneously because the webbing sensor 40 is in direct contact with the webbing 12.
  • the arm 44 pivots and the sensor 96 provides a particular voltage to the servo amplifier 102.
  • the voltage has a polarity for properly extracting or refracting the webbing based on the change in tension.
  • the servo amplifier 102 amplifies the voltage to a level that will activate the motor 32.
  • the activated motor 32 rotates the spool 14 in the appropriate direction to either exfract or refract the webbing 12.
  • the seat belt webbing sensor 40 detects movement of the webbing 12 by the motor 32. hi response, the webbing sensor 40 gradually adjusts the control signal (the voltage magnitude) sent to the motor 32 until the predetermined tension is again present in the webbing 12.
  • the load feedback control loop 110 and the seat belt webbing sensor 40 provide advantages over conventional systems.
  • the load feedback control loop 110 allows an electric seat belt retractor 10 to gradually extract and retract the webbing 12 without overshoot or undershoot motion control errors.
  • the seat belt webbing sensor 40 senses tension directly from the webbing 12, the feedback control system 100 is automatically calibrated for use in almost any seat belt system. Direct sensing by the webbing sensor 40 allows the retractor 10 to quickly respond to motion of the webbing 12.
  • the analog load feedback control loop 110 allows the system 100 to operate without complicated or expensive control modules.
  • Such a feedback control system 100 may be utilized in a wide variety of control systems in which a load is to be moved with speed and precision.
  • the feedback control system 100 may be used in manufacturing, automated distribution, vehicle systems, and a wide variety of other applications.
  • the feedback control system 100 may provide particular benefits in systems in which the tension of a flexible member such as a belt, cable, or the like, is to be continuously adjusted. Adaptation of the feedback control systems described above to such applications is within the ability of those of skill in the art with the aid of the present disclosure.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Automotive Seat Belt Assembly (AREA)

Abstract

Un rétracteur électrique déroule et enroule une ceinture de sécurité en réponse à une tension dans la ceinture de sécurité. Le rétracteur électrique peut comprendre une bobine fixée rotative à un cadre de rétracteur. Une ceinture de sécurité est enroulée sur la bobine. La bobine est mise en rotation par un moteur via un système de vis sans fin qui permet un mouvement axial limité dans la vis sans fin mais empêche, d'une manière générale, que le moteur ne soit rétroactionné par une tension dans la ceinture de sécurité, afin d'empêcher l'extraction forcée de la ceinture de sécurité. Le système de vis sans fin peut également couper l'alimentation du moteur dans le cas d'une tension excessive dans la ceinture de sécurité afin d'empêcher un déroulement supplémentaire de la ceinture de sécurité. Un détecteur de sangle de ceinture de sécurité détecte la tension dans la ceinture de sécurité et il active le moteur afin de rétracter ou de dérouler la ceinture de sécurité du rétracteur. Un système de commande d'urgence peut prendre la priorité sur la commande de guide de bande en réponse à une dynamique anormale du véhicule pour générer une pré-tension avant accident et/ou une pré-tension d'accident réversible.
PCT/US2004/015814 2003-05-19 2004-05-18 Systeme de retracteur electrique de ceinture de securite WO2004103782A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP04752769A EP1625055A1 (fr) 2003-05-19 2004-05-18 Systeme de retracteur electrique de ceinture de securite

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US10/440,698 US6935590B2 (en) 2003-05-19 2003-05-19 Sensor for a feedback control system
US10/440,698 2003-05-19
US10/459,353 US7140571B2 (en) 2003-06-11 2003-06-11 Electric seat belt retractor system
US10/459,353 2003-06-11

Publications (1)

Publication Number Publication Date
WO2004103782A1 true WO2004103782A1 (fr) 2004-12-02

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004060148A1 (de) * 2004-12-14 2006-06-22 Trw Automotive Gmbh Vorrichtung zum Straffen eines Sicherheitsgurts
US20130073149A1 (en) * 2010-03-25 2013-03-21 Bayerische Motoren Werke Methods and Devices for Controlling a Precrash Safety System in a Motor Vehicle
DE102005019898B4 (de) * 2005-04-29 2016-05-04 Bayerische Motoren Werke Aktiengesellschaft Gurtdruckregelung
CN105774749A (zh) * 2016-03-03 2016-07-20 东方久乐汽车电子（上海）有限公司 一种新型预警式安全带

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US3182923A (en) * 1963-05-15 1965-05-11 Botar Bela Seat belt reel mechanism
GB1210323A (en) * 1968-06-22 1970-10-28 Sigmatex Ag Self-locking safety belts
US4261530A (en) * 1978-07-03 1981-04-14 Kabushiki-Kaisha Tokai-Rika-Denki-Seisakusho Webbing locking mechanism
JPS62275861A (ja) * 1986-05-23 1987-11-30 Ashimori Ind Co Ltd シ−トベルトのリトラクタ−
DE3727929A1 (de) * 1987-08-21 1989-01-19 Daimler Benz Ag Gurtspannungs-ueberwachungsvorrichtung fuer eine gurtkomforteinrichtung
US5005777A (en) * 1988-12-09 1991-04-09 Angel Fernandez Seat belt retractor with an electric motor
EP0800970A1 (fr) * 1996-04-05 1997-10-15 Takata Corporation Rétracteur pour ceinture de sécurité avec moteur à ultrason
US20010025735A1 (en) * 1997-12-16 2001-10-04 Nsk Ltd. A Japanese Corporation Automotive passenger restraint and protection apparatus
US20020180201A1 (en) * 2001-06-01 2002-12-05 Nye Theodore W. Vehicle occupant safety system with an electric motor driven pretensioner

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Publication number Priority date Publication date Assignee Title
US3182923A (en) * 1963-05-15 1965-05-11 Botar Bela Seat belt reel mechanism
GB1210323A (en) * 1968-06-22 1970-10-28 Sigmatex Ag Self-locking safety belts
US4261530A (en) * 1978-07-03 1981-04-14 Kabushiki-Kaisha Tokai-Rika-Denki-Seisakusho Webbing locking mechanism
JPS62275861A (ja) * 1986-05-23 1987-11-30 Ashimori Ind Co Ltd シ−トベルトのリトラクタ−
DE3727929A1 (de) * 1987-08-21 1989-01-19 Daimler Benz Ag Gurtspannungs-ueberwachungsvorrichtung fuer eine gurtkomforteinrichtung
US5005777A (en) * 1988-12-09 1991-04-09 Angel Fernandez Seat belt retractor with an electric motor
EP0800970A1 (fr) * 1996-04-05 1997-10-15 Takata Corporation Rétracteur pour ceinture de sécurité avec moteur à ultrason
US20010025735A1 (en) * 1997-12-16 2001-10-04 Nsk Ltd. A Japanese Corporation Automotive passenger restraint and protection apparatus
US20020180201A1 (en) * 2001-06-01 2002-12-05 Nye Theodore W. Vehicle occupant safety system with an electric motor driven pretensioner

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004060148A1 (de) * 2004-12-14 2006-06-22 Trw Automotive Gmbh Vorrichtung zum Straffen eines Sicherheitsgurts
DE102005019898B4 (de) * 2005-04-29 2016-05-04 Bayerische Motoren Werke Aktiengesellschaft Gurtdruckregelung
US20130073149A1 (en) * 2010-03-25 2013-03-21 Bayerische Motoren Werke Methods and Devices for Controlling a Precrash Safety System in a Motor Vehicle
US8606466B2 (en) * 2010-03-25 2013-12-10 Bayerische Motoren Werke Aktiengesellschaft Methods and devices for controlling a precrash safety system in a motor vehicle
CN105774749A (zh) * 2016-03-03 2016-07-20 东方久乐汽车电子（上海）有限公司 一种新型预警式安全带

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