192 clutches and power-stop control – Clutches – Operators
Patent
1997-06-02
1999-07-06
Lorence, Richard M.
192 clutches and power-stop control
Clutches
Operators
192 71, 242374, B60R 2246, F16D 4324
Patent
active
059187174
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a rotary drive apparatus for a belt tensioner comprising a casing in which a cylinder space is formed, a generally circular disk-shaped rotor mounted eccentrically therein having vanes accommodated in radial slots and a compressed gas source for pressurizing the chambers formed between the vanes, the rotor and the wall of the casing.
A drive apparatus of this kind is already known from German patent 28 14 487. Since the rotor of this drive apparatus is directly coupled to the belt reel of a belt retractor, good utilization is made of the energy made available by the compressed gas source as compared to other types of belt tensioners in which a linear movement first needs to be translated into a rotary movement. The compressed gas source, a pyrotechnical inflator, pressurizes the cylinder spaces formed between the vanes of the rotor in this known drive apparatus, however, not directly but by means of a liquid working medium such as water, since it fails to adequately seal off the rotor in the casing without detrimenting smooth running of the belt reel in the belt retractor by the coupled rotor.
The invention provides for a rotary drive apparatus for a belt tensioner in which the chambers are directly pressurizable by the compressed gas from the compressed gas source and the rotor is not drivingly coupled to a shaft until the compressed gas source is activated, said shaft being coupled to the belt reel of the belt retractor so that the rotation of the belt reel is not obstructed in normal roll up and roll off operation.
In the case of the rotary drive apparatus according to the invention, the chambers are sealed off both with respect to each other and to the casing by a sealing system on the rotor, and the rotor is mounted on the casing and is rotatable with respect to a shaft and carries at least one pivotally mounted clutch pawl which is engagingly positionable in a clutch toothing on the circumference of the shaft. The sealing system ensures minor losses when the chambers are pressurized directly by the gases given off by the compressed gas source. The clutch pawl arranged between shaft and rotor permits decoupling of the rotor from the shaft in the normal resting position. Preferably, the clutch pawl is maintained out of engagement with the clutch toothing on the shaft by a spring in a resting position and is moved by the forces of inertia on acceleration of the rotor into engagement with the clutch toothing.
On completion of belt tensioning, the clutch pawl is moved back by the spring into the resting position in accordance with one preferred embodiment so that the rotor is again decoupled from the shaft. The belt reel of the belt retractor connected to the shaft is then again free to rotate as if the normal function of the belt retractor were reinstated. This function is important especially when the belt tensioner has been activated, e.g. in the case of a minor collision but leaving the car still capable of being driven so that it can be moved from the road or to a repair shop. In this case, the vehicle occupant is able to buckle up again after having removed the belt. Although the rotary drive apparatus can no longer be actuated, the belt retractor including its automatic blocking feature still works, however, as a belt retractor without a belt tensioner.
Due to the preferred arrangement of the clutch pawl in a recess in the face of the rotor between two adjacent vanes the coupling function is integrated in the rotary drive apparatus without magnifying its space requirement. In order that the clutch pawl, despite the compact configuration, is able to handle large forces, it is preferably crowned rounded at its end facing away from the tip of the pawl and supported by a correspondingly rounded surface of the recess.
Further features and advantages of the invention will be evident from the following description and the drawing to which reference is made, in which:
FIG. 1 is an exploded view of the rotary drive apparatus in accordance with a first embodiment;
FIG. 2 is a side vi
REFERENCES:
patent: 2713769 (1955-07-01), Johnson
patent: 4455000 (1984-06-01), Nilsson
patent: 5351485 (1994-10-01), Hiruta
patent: 5451008 (1995-09-01), Hamaue
patent: 5653398 (1997-08-01), Fohl
patent: 5730384 (1998-03-01), Fohl
patent: 5749536 (1998-05-01), Specht et al.
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