Retractor with ALR mode of operation with vehicle sensor block-out

A belt retractor having ELR and ALR modes of operation is disclosed. The retractor comprises a sensor pawl movable between a released and a locked position with one or more teeth of a ratchet wheel rotatable with a spool of the retractor; the sensor pawl forming part of both ELR and ALR locking mechanisms. A spring biased first lever is rotatable to a first position and when in the first position urges the sensor pawl toward engagement with the ratchet wheel. The lever is movable to a second position, which permits the sensor pawl to move away from the ratchet wheel teeth thereby preventing the retractor from entering into its ALR mode of operation. The lever, when in its second position, biases the sensor pawl into engagement with a cooperating inertial mass that is part of a vehicle sensitive locking mechanism of the seat belt retractor. This bias force operative on the sensor pawl is effective to limit the motion of the inertial mass to lessen or eliminate vibrational movement of the inertial mass relative to the sensor pawl and movement relative to a support basket or support structure that holds the inertial mass thereby lessening acoustic and vibrational noise created by the movement and rattling of the sensor pawl and/or inertial mass.

The present invention relates generally to safety restraint systems for motor vehicles. More specifically, the present invention is directed to an improved seat belt retractor having both ELR and ALR functionality.

As known in the art, ELR means an emergency locking retractor, which typically includes one or more inertial locking mechanisms, as more particularly illustrated in European Patent application EP0228729A1, which is incorporated herein by reference. The typical ELR seat belt retractor includes both a vehicle sensitive locking mechanism and a web sensitive locking mechanism. Often the vehicle sensitive locking mechanism and the web sensitive locking mechanism share common parts, which results in a more cost-effective seat belt retractor.

Quite often, the vehicle sensitive locking mechanism includes a first housing member that is rotationally mounted relative to a side of the retractor frame as well as to the retractor spool. This first housing member is called, in some literature, a lock cup. This first housing member supports a movable inertial mass configured as a ball or standing man. Sudden acceleration or acceleration in excess of a first limit value or severe rotation beyond a limit of the vehicle value causes movement of this inertial mass, which initiates lockup of the retractor. The first housing member typically includes a rotationally supported pawl, also referred to as a sensor pawl since it cooperates with the inertial mass. Movement of the inertial mass causes movement of the sensor pawl from a deactivated position to an activated position.

In the activated position the inertial pawl engages one or more teeth of a ratchet wheel; the ratchet wheel is loosely supported for rotation about the rotational axis of the spool and rotationally movable with the retractor spool. The engagement of the sensor pawl with the ratchet wheel links the ratchet wheel to the spool, which causes the lock cup member to rotate with the rotating spool. The rotation of the lock cup in concert with the rotation of the spool causes a lock pawl to move into engagement with the one or more teeth of another ratchet wheel (also referred to as a lock wheel). The lock wheel and the ratchet wheel that cooperates with the sensor pawl can be the same part. Engagement of the lock pawl with the teeth of the lock wheel leads to the initial lockup of a typical seat belt retractor.

When the seat belt tongue is removed from a cooperating seat belt buckle, the extended seat belt (also called seat belt webbing or webbing) will be retracted onto the spool in response to a bias force typically provided by a rewind spring of known construction. The rewind spring will rewind all of the available seat belt webbing onto the spool, so that the seat: belt retractor is ready for its next use cycle. This condition is typically called the stowed condition, as the seat belt webbing is now stowed or rewound onto spool. In this mode of operation it is anticipated and often required that the ELR locking mechanisms are in a deactivated condition so that the seat belt webbing is free to be extended (protracted) or retracted without intervention of the ELR locking mechanisms, that is the vehicle sensitive or web sensitive locking mechanisms. Occasionally, as reported in literature, as the seat belt webbing is moved to the stowed position, the vehicle sensitive locking mechanism inadvertently will assume an undesirable locked condition, which prevents the seat belt from being easily extended from the retractor. Fortunately this condition is usually temporary. This is an undesirable condition, which is avoided in the present invention by biasing the sensor pawl, when the seat belt is in a stowed condition, away from the ratchet wheel, preventing such an inadvertent lock condition of the retractor. Also, if the retractor is mounted in a movable seat back, this feature will prevent the retractor from locking up as the seat back is moved.

As mentioned, it is also commonplace for an emergency locking seat belt retractor to include ALR functionality. When in the ALR mode of operation, the vehicle sensitive and web sensitive locking functions are bypassed. As known by those skilled in the art, ALR functionality of the seat belt retractor is typically activated as the seat belt webbing is secured about a child seat. As also known by those skilled in the art, the acronym ALR stands for automatically locking retractor. In most situations, to activate the ALR mode of operation, most if not all of the seat belt webbing is manually pulled out or protracted from the spool prior to the seat belt being placed about a child seat. Then the seat belt is released to envelop the child seat. As the last section of seat belt webbing is protracted from the spool, the prior art retractor enters its automatic locking mode (ALR) mode of operation.

ALR mechanisms often include one or more gear devices, which rotate with the retractor spool and which provide an effective measurement of the length of webbing that has been removed from the spool. As the webbing is pulled from the spool, the ALR mechanism typically presents a mechanical feature, which causes the retractor to enter into its automatic locking mode of operation. For example, the one such ALR mechanism as shown in U.S. Pat. No. 5,904,371, which is incorporated herein by reference, selectively biases an ALR pawl into engagement with a ratchet wheel on extension of the last section of the seat belt. Biasing the ALR pawl into the ratchet wheel initiates retractor lockup as provided by the vehicle sensitive locking mechanism. The seat belt retractor will remain in its ALR mode of operation as the length of protracted webbing is rewound on the spool and will return the retractor to its ELR mode of operation upon full retraction of the belt.

The ALR mechanism in the above-referenced patent includes a spring-loaded lever that is physically maintained out of engagement with the ALR pawl. More specifically, the spring-loaded member is biased onto an edge of a cam disk that rotates with the spool. After a predetermined number of spool rotations corresponding to the removal of virtually all of the webbing from the spool, the cam disk is rotated into a position to present a notch to the spring-loaded lever. Thereafter the spring-loaded lever falls into the notch, engages a surface of the ALR lever and moves the ALR pawl into engagement with one of the teeth of the ratchet wheel to initiate lock-up of the retractor.

In the present invention a single lever, in cooperation with other components, is used to control the locking mode (ELR/ALR) of the seat belt retractor. When the seat belt is fully stowed on the retractor spool, the lever is moved to a position that biases a sensor pawl upon a vehicle inertia mass to effectively block out the ELR mode of operation. Upon protraction of a small yet determinable amount of webbing, the retractor enters into an ELR mode of operation. During its normal mode of use, such as with some of the seat belt webbing protracted about the occupant, the retractor will remain in the ELR mode of operation, however, the ALR mode of operation is not accessible until after all of the seat belt has been pulled from the retractor.

This extension of the seat belt occurs when the seat belt is being placed, for example, about a child seat. In the ELR mode of operation the lever is displaced from the sensor pawl, and the sensor pawl and the vehicle inertia mass are permitted to move in response to vehicle dynamic conditions. In the ALR mode of operation the lever biases the sensor pawl into a cooperating ratchet wheel. The change into the automatic locking mode (ALR) is effective not upon the protraction of the last section of seat belt webbing but upon the initial angular rotation of the spool, in the direction of retraction from the fully protracted condition. Entering into the ALR mode of operation at the beginning of seat belt retraction causes less strain on the sensor pawl than when initiating the ALR mode on the full extension of the webbing.

It is an object of the present invention to provide an improved seat belt retractor.

Accordingly the invention comprises: a seat belt retractor having ELR and ALR modes of operation. The retractor comprises a sensor pawl movable between a release and a locked position with one or more teeth of a ratchet wheel rotatable with a spool of the retractor; the sensor pawl forms part of both ELR and ALR locking mechanisms. A spring biased first lever is movable between various positions in which the sensor pawl is enabled or disabled to effect ELR block-out, ELR operation and ALR operation. The lever is rotatable to a first position and when in the first position urges the sensor pawl toward engagement with the ratchet wheel, permitting ALR operation. The lever is movable to a second position, which urges the sensor pawl away from the ratchet wheel teeth thereby preventing the retractor from entering into its ELR mode of operation. The lever, when in its second position, biases the sensor pawl into engagement with a cooperating inertial mass that is part of a vehicle sensitive locking mechanism of the seat belt retractor. This bias force (operative on the sensor pawl) is effective to limit the motion of the inertial mass to lessen or eliminate vibrational movement of the inertial mass relative to the sensor pawl (as well as movement of the sensor pawl) and movement relative to a support basket or support structure that,holds the inertial mass, thereby lessening acoustic and vibrational noise created by the movement and rattling of the sensor pawl and/or inertial mass. When the lever is in a mid-position the sensor pawl and vehicle mass are free to move and the retractor is in its ELR mode of operation.

Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

Reference is made toFIGS. 1 and 2, which diagrammatically illustrate seat belt retractor20incorporating the present invention. The retractor20includes a frame22that rotationally supports this spool24in a known manner. Seat belt webbing28is wound about the spool24and can be protracted from and rewound onto the spool. The retractor20includes a primary locking system30, which comprises lock wheel32(also known in the art as a ratchet wheel) having a plurality of teeth34and a lock pawl36having one or more teeth38. This lock pawl may also include a pin39that functions as a cam follower.

The present retractor20is a dual mode retractor having ELR and ALR modes of operation. When in the ELR mode of operation retractor20utilizes inertial locking mechanisms to initiate the lockup of the retractor that effects movement of lock pawl36into engagement with lock wheel32. These inertial locking mechanisms are generally referred to as a vehicle locking mechanism40comprising a movable mass42and sensor pawl44(seeFIG. 2). The sensor pawl includes an extending pin or projection45. The sensor pawl is movable by a co-acting lever130into (and away from) ratchet wheel46(seeFIG. 1) having teeth48; the wheel46rotates with and can be part of the spool24.

As is known in the art, movement of the inertial mass42in response to excessive levels of vehicle deceleration (or large displacement of the vehicle in roll or yaw, or rotation of the surface upon which the retractor is mounted such as a seat back) causes the mass to move, roll or tip and engage an adjacent surface44aof pawl44, thereby placing pawl44into engagement with the teeth of ratchet wheel46. Rotation of the ratchet wheel46with the sensor pawl engaged causes rotation of an associated lock cup60(seeFIG. 2; also shown in phantom line inFIG. 1) which initiates the locking up of the retractor. Lock cups such as60are spring biased, typically against the frame22or other stationary retractor member, such spring being shown by arrow68, which react against a boss or projection69(on the frame).

As with many seat belt retractors, retractor20utilizes a lock cup60to support the inertial mass42, which is supported by a basket42aor other known support structure. The basket is received within a well61of the lock cup60. The basket can be fixed or movable relative to well61. As mentioned above, engagement of the sensor pawl44to the ratchet wheel46couples the lock cup60to the ratchet wheel46(or to the spool24) causing the lock cup to rotate with the spool (at least for some limited number of degrees) in a known manner. The rotation of the lock cup moves the lock pawl36into engagement with the teeth of the lock wheel32thereby completing the initial phases of the locking of the seat belt retractor. For example, the lock cup60may include a cam66into which is received the cam follower39of the lock pawl36. The rotation of the lock ring60rotates the lock pawl36about axis36a(seeFIG. 1) into engagement with the teeth of the lock wheel32.

As is known in the art, if the seat belt retractor20includes an energy absorber mechanism such as a torsion bar, after the retractor20is initially locked up, the spool is permitted to rotate and the seat belt permitted to protract from the spool24in a controlled manner as the torsion bar twists. The retractor20may also include a web sensor (not shown), as known in the art, which initiates a locking up of the seat belt retractor in response to an excessive rate of extension of the web from the retractor. This web sensor is housed in the lock cup as shown in U.S. Pat. No. 5,904,371 and EP patent application EP0228729A1, which have been incorporated by reference. Activation of the web sensitive locking mechanism also couples the lock cup to the spool, thereby also causing engagement of the lock pawl and lock wheel.

Retractor20will remain in its ELR mode of operation during all times with the exception of when all of the seat belt webbing has been retracted upon the spool, that is, the stowed condition, or when in the ALR mode of operation, which occurs in conjunction with the seat belt webbing being placed about a child seat.

The ALR locking mechanism80of the present invention utilizes a number of components known in the art. These known components include a ring gear79, a center or eccentric gear90, a movable or wobble gear100and a cam disk110, shown both inFIGS. 2 and 3. The ring gear80has a plurality of teeth82and is, in the preferred embodiment of the invention, integrally formed on a surface of the lock cup60. The center (eccentric) gear90is secured to and rotatable with spool24. The spool24includes a stub axle or projection27(seeFIGS. 1 and 3) that extends through opening62in the lock cup and is received within a bore on a rear surface of the center gear, thereby permitting the center gear90to move with the spool. The center gear90includes an eccentric outer surface92received within an opening102of the movable (wobble) gear100and a raised surface94that is concentric with opening62and received within an opening112of a cam disk110.

The movable (wobble) gear100has a centrally located opening102and a plurality of teeth104engageable with the teeth82of the ring gear80. As the center gear90rotates with the spool, the movable gear rotates and orbits about the ring gear80. The movable gear100further includes an upstanding pin or projection106.

The cam disk110has a concentric outer surface forming a cam surface114; the cam surface includes at least one major indentation116(and an optional minor indentation116ahaving a small depth). The cam disk110further includes an arcuate slot118into which the projection106of the movable gear100is received. As will be seen from the description below, the retractor will enter into its ALR mode of operation when a lever is permitted to fully enter into the indentation116.

Prior art ALR mechanisms (seeFIGS. 3 and 4) also include a spring-loaded lever230(see element102of U.S. Pat. No. 5,904,371) which functions as a cam follower232and also is used to activate an ALR pawl234(see pawl80of U.S. Pat. No. 5,904,371) to initiate the ALR mode of operation. The present invention also includes a spring-loaded lever referred to by numeral130, which incorporates the above functions and also incorporates new functionality, as mentioned above, compared to the prior art. Lever130includes a known type of a projection132, which functions as a cam follower. As will be seen, the cam follower132is biased against the cam surface114by a bias spring130a(occasionally shown as an arrow).

As mentioned earlier, the prior art ALR mechanism is activated upon the extension of virtually all of the seat belt from the spool24.FIGS. 3 and 4are illustrative of the operation of a prior art retractor and used for the purpose of illustration of some of the components of retractor20. In the prior art ALR mechanism with all of the seat belt webbing rewound about the spool, the various components of the ALR mechanism will achieve a positional orientation as generally shown inFIG. 3. The cam follower232will position itself in the minor indentation116a, which prevents premature movement of the cam disk110. As the webbing is pulled from the spool, the spool rotates thereby causing the center gear90to rotate, which in turn moves movable gear100, which in turn causes the projection106to rotate and orbit about the ring gear80, as well as causing the projection106to move within slot118of the cam disk110. As more and more seat belt webbing28is protracted from the spool, the projection106will be moved a sufficient distance to contact end120(seeFIG. 4) of slot118, thereby causing the cam disk110to rotate with the moving gear100.

The gear mechanism is configured such that when virtually all of the webbing has been removed from the spool the cam disk110will present the slot116to the cam follower232(in the prior art), which causes the cam follower to be pushed into the slot116(seeFIG. 4). This action does not happen in the present invention because of the invention of a second cam disk150. Thereafter the lever230lifts the ALR pawl234into engagement with the teeth of the ratchet wheel46to initiate the ALR mode of operation (which, as can be appreciated, is initiated upon full or substantially full extraction of the seat belt). As mentioned, the prior art retractor will remain in this mode of operation until the webbing24is fully retracted. In the prior art ALR mechanism, as the webbing24is retracted the center gear moves oppositely causing the movable gear90and the projection106to move opposite to its prior motion. As the webbing is retracted, the projection106engages the opposite end122of slot118, pushing the cam disk oppositely (counter-clockwise inFIG. 3). Such motion urges the cam follower132to move up a sloped surface124of slot116and become repositioned on the outer surface of the cam surface114. This motion disengages the lever from the ALR pawl and ends the ALR mode of operation.

Returning to the present invention, reference is again made toFIGS. 2 and 5, more particularly, the lock cup60includes a plurality of resilient inwardly directly flexible tabs64uniformly positioned about the ring gear80and concentric with opening62of the lock cup60. The cam surface114is received within these tabs64, which position the cam disk110concentric with the opening62(as well as the axis of rotation of the spool24). Each tab64has an upraised wall portion64aas well as an inwardly extending wall portion. The cam surface114rides against an inner wall of the upraised wall portion64awhile the inwardly directed wall portion64bprevents the outer edge of the cam disk from moving away from the lock cup and ring gear.

As mentioned, the ALR mechanism of the present invention further includes a second cam disk150that assists in controlling the start of the ALR mode of operation to begin upon rewind of the spool after full extension of the webbing. The second cam disk, in concert with lever130, also provides a controlled biasing of the sensor pawl44to provide a stabilizing force upon the sensor mass42at or near the complete retraction of the seat belt upon the spool to eliminate a source of vibration and noise. The cam disk150also permits the lever to achieve a mid-position to enable ELR mode of operation.

The second cam disk150includes a circular annular shaped wall152having a thin internal rim153; the rim153is rotationally supported by the first cam disk110. More particularly, the first cam disk110includes a plurality of inwardly directed tabs156similar in construction to the tabs64. Tabs156include a first wall portion158aextending away from the surface of the cam disk110and an outwardly directed portion158b. An inner surface of portion158aradially stabilizes the annular wall152while portion158bholds rim153, and hence, the second cam disk150. The second cam disk150further includes an inwardly directed socket160having an opening162therein to loosely receive the projection106of the moving gear100. The second cam disk also includes a first lobe or cam surface164positioned generally opposite the socket160and a second lobe or cam surface166.

As the seat belt webbing is extended from the spool (from a fully stowed condition to a fully extended condition), the projection106of the wobble gear100generally orbits in a circle centered upon an axis collinear with the axis of the spool while simultaneously rotating or oscillating, at a higher frequency, about the circle, such movement constrained to be within the slot118. The slot118affords the locking mechanism a degree of lost motion, that is when the projection106is not pushing on the ends of the slot118, the first cam disk110will not move. The projection106directly moves the first cam disk in a clockwise manner in relation toFIG. 6(during web extraction) and in a counter-clockwise manner (during web retraction). Additionally, as the projection or pin106moves as described, it also rotates within the opening162of socket160of the second cam disk150, and carries the second cam disk150with the pin106. As can be appreciated, second cam disk150will rotate clockwise and counterclockwise generally following the rotation of the wobble gear100.

FIG. 6shows the position of the various disks with the seat belt stowed on the spool. In this position, cam surface166urges the cam follower132away from cam surface114of cam disk110. Cam surface166moves the cam follower132a greater distance away from the center of the spool.

As the seat belt webbing is extended from the retractor, the spool will rotate in a clockwise direction (in relation toFIG. 6); the various components of the gearing mechanisms will similarly rotate. As the webbing is extracted, the wobble gear100(via projection106and socket160) moves the second cam disk150in a clockwise manner (see arrow on the second cam disk). The first cam disk will generally remain in its initial position as the projection (pin)106is moved away from end122of slot118(into a free zone). After the seat belt has been slightly extended, the second cam disk will be moved (by projection106) sufficiently clockwise to permit the cam follower132to fall onto cam surface114of the first cam disk110. In this mode of operation, the cam follower132moves inwardly to cam surface114, which moves the end140of lever130away from the pin45of the sensor pawl44. This action permits the retractor to enter into its ELR mode of operation and is shown inFIG. 6ain which the sensor mass and the sensor pawl are not restricted from moving.

As mentioned above and shown inFIG. 5, the lever130is rotationally mounted to the lock cup60. However, the lock cup is not shown inFIGS. 6,6a,7and8. Only a pin60a(which is part of the lock cup and which rotationally supports the lever130) is shown.

The second cam disk150is configured to be located above the slot116(of cam disk110) generally just before all of the webbing28has been extracted as shown inFIG. 7. As can be appreciated, the placement of the lobe or surface164above the slot116prevents the cam follower132of lever130from entering into the slot116, thereby preventing the retractor from entering into its ALR mode of operation on full extraction of the webbing28, as taught by the prior art. The dimension of the radial distance of surface164is not critical, it can be the same as the radial distance of surface114, slightly smaller or greater as it acts as a blocking surface. Upon release of the webbing28or the reduction of the force holding the webbing in its extended condition, the webbing will begin to be rewound upon the spool by operation of the rewind spring29(seeFIG. 1). This change of direction of the spool24causes the center (eccentric) gear90to rotate oppositely causing the moving (wobble) gear100to move oppositely as well (counterclockwise inFIG. 7).

This action causes movement of the projection (pin)106away from end120of slot118, which moves the second cam disk150in a counterclockwise direction opposite to its motion when the seat belt was being extended. Upon a determinable amount of rotation of disk150, the cam follower132is permitted to slide upon edge170of lobe166, and enter into groove116(seeFIG. 8), as this action permits the lever130to move inwardly. Inward movement of lever130raises the pin45of the sensor pawl44and moves sensor pawl44into engagement with the teeth of ratchet gear46to now begin the ALR mode of operation as the spool rotates in the direction of seat belt retraction.

As the spool rotates in a rewind direction the projection106continues to move the second cam disk150in synchronism with the movement of the projection106. After a determinable amount of webbing has been rewound onto the spool, the projection106will eventually engage end122of slot118, thereby reengaging cam disk110. Subsequently, the first cam disk110is pushed (rotated) back to its initial position corresponding to a fully rewound spool shown inFIG. 6, completing the cycle and positioning lobe166under the cam follower132, thereby biasing the lever130downwardly or outwardly (inFIG. 6) away from surface114or in a counterclockwise manner (as viewed in relation toFIG. 2).

As described more fully below, when the lever130is pushed outwardly upon engagement with the lobe166of the second cam disk150, the pin45(of the sensor pawl44) is biased downwardly by a surface to hold the sensor pawl44upon the top of the inertial mass42. The above-mentioned lever130includes a distal end134having a ring136defining an opening138. The pin45of the sensor pawl44is received within opening138of the ring136. One end140of the ring forms a first engagement surface and an opposite end142of the ring forms a second engagement surface. When the lever130moves into groove116the second engagement surface142lifts the pin45and hence the sensor pawl44into engagement with the ratchet wheel46(as shown inFIG. 8) initiating the ALR mode of engagement. On return of the webbing to the spool as shown inFIG. 6, the engagement surface140urges the pin45, and hence the sensor pawl44, downwardly onto the sensor mass44, preventing the locking mechanism from becoming activated in the stowed position, regardless of the physical orientation of the retractor. As can be appreciated, the lever130assists in initiating the ALR mode of operating by moving the sensor pawl and also acts to block the ELR mode of operation by preventing movement of the sensor pawl.

Many changes and modifications in the above-described embodiment of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, that scope is intended to be limited only by the scope of the appended claims.