Winding – tensioning – or guiding – Reeling device – With spring motor
Patent
1998-05-12
1999-05-25
Jillions, John M.
Winding, tensioning, or guiding
Reeling device
With spring motor
B60R 2246
Patent
active
059063262
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a belt tightening device for a seat belt retractor.
In the normal driving operation of a motor vehicle, the seat belt rests relatively loosely against the vehicle occupant's body. In the event of an accident, there will then be the danger that, despite the blocking of the winding shaft of the seat belt retractor, the vehicle occupant's body can move too far toward the front. Also, the belt strap layers are wound relatively loosely onto the winding shaft of the belt retractor so that, despite the blocking of the winding shaft, this looseness of the belt may result in a considerable displacement of the vehicle occupant to the front because of a film spool effect.
From European Patent Document EP 0 629 531 A1, an arrangement is known for a pyrotechnic rotational drive of a winding shaft of a seat belt retractor which has two piston-shaped driving bodies which can be moved by the driving force of pyrotechnic propellent charges on straight or curved guideways. The driving bodies have toothed-rack-type toothings which can be engaged with a winding shaft gear wheel so that they mesh with these and in the process translate their longitudinal movement into a rotation of the winding shaft gear wheel. The ignition of the propellent charge of the second driving body can be triggered in a manner which is controlled such that the two driving bodies drive the winding shaft gear wheel in a chronological succession.
From German Patent Document DE 44 29 731 A1, a transmission is known for transmitting the driving movement of a belt tightening drive to a belt spool of a seat belt retractor. The transmission is constructed as an epicycloidal gear system and particularly as a planetary gear system with a stationarily arranged ring gear and at least one planet gear which is affected by the belt tightening drive, and having a sun gear which is connected with the belt spool in a connectable or non-rotatable manner. The planet gear is driven by means of a belt tightening drive which is constructed as a gas generator and, by way of a propellant gas duct, drives a piston which is connected with the planetary gear shaft by way of a connecting rod. The ring gear, the sun gear and the planet gear have external toothings which engage with one another. When the gas generator is ignited, the planet gear rolls on the stationary ring gear as the result of the generated thrust motion. The sun gear is rotated simultaneously. When two planet gears are used, these are connected with one another by means of a connecting rod in order to carry out a joint thrust movement when ignited simultaneously. However, the planetary gear system requires considerable installation space which makes a compact arrangement on a seat belt retractor difficult.
In contrast, it is object of the present invention to improve the arrangement with respect to a compact construction and to its operability.
Whereas, in the case of the first-mentioned state of the art, the speed and the length of the driving body, which is moved tangentially along the winding shaft gear wheel, determine the rotational speed and the angle of rotation of the winding shaft, in the case of the belt tightening device according to the invention, only a planet gear is guided in the housing on a moving path which is as short and as space-saving as possible, in which case it causes the central sun gear to rotate. By a suitable selection of the ratio of the size of the planet gear to that of the sun gear, the required belt tightening path and the winding shaft rotation required for this purpose can be achieved without an additional transmission between the sun gear and the winding shaft. Because of the two successively ignited drive units, the driving power will be generated longer and will be distributed along the movement path with acceleration courses which can be set by the ignition characteristics. The sun gear may be connectable with the winding shaft by way of a clutch, as described, for example, in German Patent Document, DE 43 27 134 A1 or DE 44 18 438 A1.
The introdu
REFERENCES:
patent: 5681004 (1997-10-01), Specht
HS Technik und Design Technische Entwicklungen GmbH
Jillions John M.
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