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
  • B60R22/46—Reels with means to tension the belt in an emergency by forced winding up
• • 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

Definitions

• the invention relates to a safety belt: retractor, especially for use in motor vehicles, having a blocking system that is controlled in a vehicle sensitive and/or belt strap sensitive manner, and also having a tensioning device, which acts on the belt shaft, for carrying out a reversible pretensioning of the occupants, whereby the belt shaft can be coupled with an electric motor, as a tensioner drive, via an interposed gear mechanism.
• a safety belt retractor having the aforementioned features is known from EP 0 893 313 A2.
• An electric motor which is rotatable not only in the belt unwinding direction but also in the belt winding direction, can be coupled to the belt shaft of the belt retractor; from the electric motor, via an interposed gear mechanism and as a function of certain driving situations, adjustable torques can be made to act upon the belt shaft.
• the torque delivered by the electric motor in a predetermined shift position of the gear mechanism, the torque delivered by the electric motor can be transferred for tensioning the belt strap on the belt shaft.
• the strapped-in occupant upon the occurrence of speed changes or deceleration values below the threshold for the triggering of the performance tensioning during an accident, is pulled via a reduced torque of the electric motor into his normal sitting position, and belt slack is removed from the safety belt. Since upon cessation of the change in speed the pretensioning is concluded, and as a reversible process can again be introduced upon the occurrence of a further appropriate driving situation, the strapped-in vehicle occupant has imparted to him a feeling of active security. If the triggering threshold for the performance tensioning is exceeded during an accident, the electric motor operates with an appropriately high torque.
• the disadvantageous situation of a self-blocking of the safety belt can occur in that via the pretensioning all belt slack is taken out of the safety belt system and the safety belt rests taughtly against the body of the strapped-in person, whereby depending upon the driving situation, at the end of the pretensioning process one cannot preclude that via a slight forward displacement of the body of the strapped-in occupant, the blocking disk of the blocking system on the side of the belt retractor will be brought into a load-transmitting engagement with a housing component.
• the basic concept of the invention is that as a gear mechanism for the connection of the belt shaft to the electric motor, a worm or spiral toothing is provided that meshes with an external toothing of the belt shaft, whereby the spiral toothing is supported against a fixed counter-bearing such that upon the occurrence of an axial loading of the spiral toothing directed against the counter-bearing due to a load acting upon the belt shaft in the belt withdrawal direction, a rotation of the spiral, for receiving a torque applied by the belt shaft, is prevented via a support force.
• the inventive concept also involves, by means of a suitable design of the spiral toothing or by means of other measures at the conclusion of the tensioning movement via a rotation of the belt shaft in the belt winding direction, the prevention of a reversal of the belt shaft, due to a load acting upon the belt shaft in the belt withdrawal direction, by preventing the rotation of the spiral toothing in the appropriate direction of rotation to such an extent that the torque applied by the belt shaft is absorbed without permitting a reversal of the belt shaft. This prevents an activation of the blocking system in an advantageous manner.
• the spiral toothing is configured in such a way that in the one direction of rotation of the spiral toothing, namely in the tensioning direction in conformity with the belt winding direction, the efficiency of the gear mechanism can be fully utilized, whereas in the opposite direction of rotation, in other words in conformity with the belt withdrawal direction, preventing rotation of the spiral is brought about in that the spiral toothing is supported against a fixed counter-bearing in such a way that with an axial loading of the spiral toothing directed against the counter-bearing due to the belt shaft, the prevention of the rotation of the spiral is brought about by the support force. To the extent that at the conclusion of pretensioning of the belt shaft a torque acts upon the spiral toothing, this leads to an axial loading of the spiral toothing that can be converted into an appropriately acting support force.
• the use of an electric motor having a gear mechanism embodied as a spiral toothing is also not precluded for the performance tensioning to the extent that the electric motor is designed to apply an appropriate torque.
• the performance tensioning can also be effected via another tensioner drive that acts upon the belt shaft, or via a tensioner, for example a buckle tensioner, that is disposed in some other region of the safety belt system.
• the spiral toothing is coupled via a miter-wheel gearing to a drive shaft of the electric motor. This involves an especially space-saving manner of construction of the safety belt retractor, because the electric motor can be disposed directly over the shaft portion of the safety belt retractor.
• a crown wheel gear mechanism is provided as a miter-wheel gearing, this results in production advantages.
• the arrangement of a bevel gearing is also conceivable, whereby the tolerance zone positions of a bevel gearing can be controlled only at great expense during mass production. In so far, however, the use of a bevel gearing to realize the invention is not precluded.
• the spiral toothing is formed on a carrier shaft, and the carrier shaft is connected to the miter-wheel gearing.
• the prevention of the spiral rotation can be carried out pursuant to an embodiment of the invention in that disposed between the counter-bearing and the first land or thread of the spiral toothing is a component that increases friction.
• the friction-increasing component can, pursuant to an embodiment of the invention, be embodied as an intermediate or spacer disk of a material having a non-linear coefficient of friction; for example elastomers are in particular available that as the effect of force increases, an exponentially increasing frictional force occurs.
• a bearing disk can be provided that deforms axially and elastically as the load increases, so that the first thread of the spiral toothing, under the effect of the support force, runs on a larger diameter in the bearing than without the, effect of the support force.
• the surface of the gear mechanism that faces the spiral toothing is provided with a conical recess, and disposed on the carrier shaft is the conical friction body that is made of an elastic material and has a corresponding shape; in this embodiment, the increase of the friction force is effected by the conical shape of the recess and of the friction body, as well as by the elastic deformation.
• a compression spring can be disposed between gear mechanism housing and spiral toothing, and carrier shaft and gear mechanism housing are provided with latching structures that interengage upon axial displacement of the carrier shaft; instead of the compression spring, a tension spring can also be disposed at the appropriate end of the carrier shaft.
• the end face of the carrier shaft is supported against a shank of the drive shaft of the electric motor, so that in this way an appropriate braking moment is produced.
• the crown wheel toothing of the crown wheel gear mechanism which is effective between drive shaft of the electric motor and the carrier shaft for the spiral toothing, can have a multi-stage configuration such that with an axial loading of the carrier shaft, the transmission of the crown wheel gear mechanism changes, thus producing a braking moment for the rotation of the carrier shaft with the spiral toothing.
• the electric motor can be designed with a further performance range for applying a holding moment that serves to aid in the prevention of the spiral rotation, so that in additional to the prevention of the spiral rotation by the electric motor, a blocking of the reversal of the spiral toothing in conformity with the withdrawal direction of the belt strap is applied via an appropriate holding moment.
• the design of the electric motor with a performance range that serves for producing a holding moment additionally presents the possibility, during a force-limiting phase that is, additionally provided with the aforementioned safety belt retractor, of establishing a controlled holding moment and hence of realizing an adaptive force limitation, for example together with a single stage or also multi-stage torsion rod.
• the holding moment of the electric motor can be adjustable by the motor control as a function of the load that acts on the belt shaft in the belt withdrawal direction.
• the carrier shaft that carries the spiral toothing is held in a bearing at its end::.that is opposite the miter-wheel gearing, is mounted in an additional axial or thrust bearing that is surrounded by a bearing housing.
• the bearing housing form the counter-bearing for the spiral toothing.
• FIG. 1 an overall view of a safety belt retractor having a pretensioning device
• FIG. 2 the safety belt retractor of FIG. 1 in a side view of its tensioner side with pretensioning device
• FIG. 3 a side view of the pretensioning device of FIGS. 1 and 2 in a detailed illustration
• FIG. 4 a first embodiment of the prevention of the spiral rotation by support of the spiral toothing against the bearing housing in a diagrammatic illustration
• FIG. 5 the subject matter of FIG. 4 in a further embodiment
• FIG. 6 the subject matter of FIG. 4 in a further embodiment
• FIG. 7 the subject matter of FIG. 4 in a further embodiment
• FIG. 8 the subject matter of FIG. 4 in a further embodiment
• FIG. 9 a diagrammatic illustration of the prevention of the spiral rotation by utilization of the radial forces in the bearings of the carrier shaft
• FIG. 10 the prevention of the spiral rotation by support of the carrier shaft relative to the drive shaft of the electric motor
• FIG. 11 the prevention of the spiral rotation by support of the carrier shaft in the crown wheel gear mechanism.
• the safety belt retractor 10 seen in FIG. 1 has a U-shaped housing 11 , in the U-legs of which a belt shaft 12 is mounted in a known manner.
• the belt shaft 12 is influenced by the action of a winding spring that is disposed in a spring cartridge 13 and which, after unwinding of the non-illustrated belt strap from the belt shaft 12 , sees to it that the belt strap is rewound onto the belt shaft 12 when the safety belt is taken off.
• a winding spring that is disposed in a spring cartridge 13
• the blocking system of the belt retractor that is not illustrated in detail and to this extent is presumed to be known; the function of the blocking system is to be controlled by control systems that act in a belt strap sensitive and/or vehicle sensitive manner.
• a pretensioner housing is additionally indicated by the reference numeral 15 ; an electric motor 16 , as a tensioner drive, is associated with the pretensioner housing.
• the drive shaft 34 of the electric motor 16 acts via a crown wheel gear mechanism 17 upon a carrier shaft 18 that is disposed in a tangential orientation relative to the belt shaft 12 ; disposed on the carrier shaft is a worm or spiral toothing 19 that meshes with an external toothing 20 disposed on the belt shaft 12 .
• the carrier shaft 18 is mounted in an end bearing 21 as well as in a cup-shaped bearing 22 that is disposed between the spiral toothing 19 and the crown wheel gear mechanism 17 , whereby the cup-shaped bearing 22 is disposed in a bearing housing 23 that is not further illustrated in FIGS. 2 and 3, yet can be seen from FIGS. 4 to 8.
• the spiral toothing 19 is not embodied as a self-blocking spiral gear, so that by means of additional structural measures care is taken that with a load that at the conclusion of a pretensioning acts upon the belt shaft 12 , in the belt withdrawal direction (arrow 42 ) the axial force (arrow 40 ) that is applied by the belt shaft 12 onto the spiral toothing 19 , and hence onto the carrier shaft 18 , is converted into a friction-increasing support force, so that in this way an arresting or preventing of the rotational movement of the spiral toothing 19 is brought about.
• Embodiments for effecting the increase of the frictional force are primarily illustrated in FIGS. 4 to 8, whereby with the embodiment illustrated in FIG. 4 an intermediate or spacer disk 25 , which is made of a material having a non-linear frictional coefficient, is disposed between the first land or thread of the spiral toothing 19 and the bearing housing 23 of the cup-shaped bearing 22 .
• This material can be a suitable elastomer with which, as the axial force increases, the frictional force increases exponentially.
• the bearing disk 26 that pursuant to FIG. 5 is disposed between the spiral toothing 19 and the bearing housing 23 acts in a similar manner, according to which under the effect of the axial force (arrow 40 ) the spiral toothing runs on a larger diameter in the bearing than under normal load.
• the bearing housing 23 is provided with a conical recess 27 into which engages a conical friction body 28 that has a corresponding shape and is made of an elastic material, so that due to the conical shape, as well as the elastic deformation of the friction body 28 , the frictional force between the spiral toothing 19 and the bearing housing 23 is increased.
• FIG. 9 illustrates the possibility of increasing the frictional force between the spiral toothing 19 and the external toothing 20 of the belt shaft 12 in that with the influence of an axial force upon the carrier shaft 18 , the latter tilts by a small angle 32 in the cup-shaped bearing 22 .
• FIG. 10 illustrates the possibility that the end face of the carrier shaft 18 is supported upon a shank 33 of the drive shaft 34 of the electric motor 16 , thereby producing an appropriate braking moment.
• FIG. 11 indicates that the crown wheel toothing of the crown wheel gear mechanism 17 that is effective between the drive shaft 34 of the electric motor 16 and the carrier shaft 18 has a multi-stage configuration such that with an axial loading of the carrier shaft (arrow 40 ), the transmission of the crown wheel gear mechanism 17 changes from rapid to slow, whereby alternatively or in addition an impairment of the toothing efficiency in the stages of the crown wheel gear mechanism 17 can be provided.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Automotive Seat Belt Assembly (AREA)
• Gear Transmission (AREA)
• Emergency Lowering Means (AREA)
• Artificial Filaments (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Related Child Applications (1)

Publications (1)

Family

ID=29557445

Family Applications (1)

Country Status (9)

Cited By (5)

Families Citing this family (23)

Citations (11)

Family Cites Families (7)

• 2003
  • 2003-05-27 AU AU2003247291A patent/AU2003247291A1/en not_active Abandoned
  • 2003-05-27 JP JP2004507119A patent/JP4437316B2/ja not_active Expired - Fee Related
  • 2003-05-27 ES ES03755139T patent/ES2295633T3/es not_active Expired - Lifetime
  • 2003-05-27 DE DE50308416T patent/DE50308416D1/de not_active Expired - Lifetime
  • 2003-05-27 AT AT03755139T patent/ATE375901T1/de not_active IP Right Cessation
  • 2003-05-27 EP EP03755139A patent/EP1507688B1/de not_active Expired - Lifetime
  • 2003-05-27 US US10/522,608 patent/US20050173580A1/en not_active Abandoned
  • 2003-05-27 WO PCT/EP2003/005545 patent/WO2003099619A2/de active IP Right Grant
  • 2003-05-27 KR KR1020047019126A patent/KR100933397B1/ko active IP Right Grant

Patent Citations (11)

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