Winding – tensioning – or guiding – Reeling device – With spring motor
Patent
1998-07-13
1999-08-31
Darling, John P.
Winding, tensioning, or guiding
Reeling device
With spring motor
B60R 2246
Patent
active
059442760
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a driving arrangement for an occupant restraint system, in particular a belt tensioner, comprising a housing assembled of several parts, in which housing a working chamber is formed as well as an accommodation space for a pyrotechnic propellant charge, the accommodation space being in fluid communication with the working chamber.
Driving arrangements of this kind are known to exist in numerous versions. Such systems are generally divided into rotary drive and linear drive arrangements. In both versions, the housing generally consists of a main body and a cover plate placed on an open side of this main body. In the case of a rotary drive, a rotor is arranged inside the housing, which may be a vane-type rotor or a rotary piston rotor. In the case of linear drives, the housing contains a cylinder with a piston movably arranged therein. The working chamber is formed in both cases between the joined housing parts. The generally cylindrical accommodation space for a pyrotechnic gas generator capsule opens into the working chamber. The housing parts are clamped against each other by means of a plurality of screws or rivets. On activation of the propellant charge in the gas generator capsule, an extremely high pressure of short duration develops in the accommodation space of the housing, which may reach a value of 400 to 500 bar or even more.
The invention proceeds from the understanding that immediately after the activation of the gas generator leakage losses occur in the accommodation space of the housing due to the high pressure, resulting in an uncontrolled compressed gas flow into the working chamber. Under these conditions of high pressure stress, the screws or rivets lengthen and a gap is formed which allows further leakage losses. If a pre-chamber is arranged between the accommodation space in the housing and the working chamber, it then becomes possible to dimension the passage section leading into the working chamber in a suitable way, and so to influence the pressure versus time profile, and to adapt it to the constructural parameters of the working piston. When the passage section leading into the working chamber is reduced, for a short time after activating the gas generator the pressure in the working chamber will be considerably lower than that in the pre-chamber. The high pressure in the accommodation space and in the pre-chamber increases the tendency of leakage losses occurring.
The invention effectively prevents the occurrence of leakage losses in the region of the accommodation space and the pre-chamber, if provided. According to the invention, a sleeve surrounding the propellant charge is provided, which sleeve is arranged as a seal between the parts of the housing in its accommodation space. The sleeve forms a sealing along the inner surface of the accommodation space, especially at the parting joint between the housing parts. The compressed gases released by the propellant charge are conducted along the inner surface of the sleeve to the working chamber. In the preferred application of the invention on a rotary drive with a vane-type rotor, a surprisingly high power increase has been noted. This is to lead back on the one hand to the avoidance of leakage losses immediately after activation of the propellant charge, and on the other hand to the additional design possibilities made available by the presence of the sleeve. The realisation that a gap may materialize between the two force-joined housing parts at the moment of activation, through which gap compressed gas escapes, is not to reach in the light of conventional consideration or general investigations. The entire driving process, from the activation of the gas generator to the belt being tensioned, proceeds within a few milliseconds, making a detailed investigation of the leakage situation almost impossible. If the sleeve is extended axially over the length of the gas generator capsule receiving the propellant charge, it may also be used for embodying a pre-chamber arranged upstream of the working chamber, in o
REFERENCES:
patent: 3982775 (1976-09-01), Lindblad
patent: 4232886 (1980-11-01), Tsuge et al.
patent: 4789185 (1988-12-01), Fohl
patent: 5366245 (1994-11-01), Lane, Jr.
patent: 5482327 (1996-01-01), Schmid
patent: 5553890 (1996-09-01), Buhr et al.
patent: 5641131 (1997-06-01), Schmid et al.
patent: 5642619 (1997-07-01), Matsuki et al.
patent: 5799977 (1998-09-01), Miyazaki et al.
patent: 5842344 (1998-12-01), Schmid
LandOfFree
Driving device for a passenger restraint system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Driving device for a passenger restraint system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Driving device for a passenger restraint system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2424049