The invention relates to a retractor for the webbing of a safety belt system according to the preamble of claim 1.
Automatic retractors for the belt of a seat belt system are part of almost every car. In the simplest still common form, such a reel consists of a housing in which a Gurtaufwickelwelle is rotatably supported against the force of a spring element, and a blocking device which the Gurtaufwickelwelle upon reaching a high vehicle acceleration and / or when reaching a high Gurtbeschleunigung against the housing blocked. To improve occupant safety, many reels continue to have a pyrotechnic tightening system. This has a propellant, which ejects gas into a pressure chamber and in this case drives a drive element which acts directly or indirectly on the Gurtaufwickelwelle. In an accident, the propellant is ignited in response to a sensor signal and thus tightened the webbing so that the occupant is held in the seat at an early stage of the accident with high force. If such a tensioner is triggered once, then the reel must be replaced.
For example, from the generic WO 2002/49887 A1
a retractor has become known, in which, alternatively or in addition to a pyrotechnic working tensioning device, an electric motor is provided, which can act by means of a gear on the Gurtaufwickelwelle. As a result, a reversibly operating tensioning device is formed, with which it is also possible in particular to carry out a tightening process when critical driving conditions are reached, even if an accident may still be avoided.
At the reelter of WO 2002/49887 A1
the electric motor extends parallel to the axis of the Gurtaufwickelwelle, wherein its first end, on which the drive shaft exits, is rigidly connected to the housing of the retractor. The drive shaft acts on the belt winding shaft via a gear having several gears.
Also the EP 1 736 383 A1
shows a belt retractor with an electromotive tensioning device. Here, both ends of the electric motor are rigidly connected to the housing, wherein the connection of the second end of the electric motor with the housing takes place by means of a motor cover, which can also be considered as part of the housing.
Such reels are often mounted in the area of the B-pillar on the inner structure of the motor vehicle and rigidly connected to the inner structure. At this place of installation, the slamming of the vehicle doors can lead to high accelerations, which are simulated in the life test with 40 G. It is usually required that the reel must endure the corresponding load at least 100,000 times. Due to the high mass of the electric motor and due to the installation type, high leverage forces occur at the connection area between the electric motor and the housing, which can lead to fatigue fracture.
On this basis, the present invention has the object to improve a generic reel to the effect that its life is improved.
This object is achieved by a reel-up with the features of claim 1.
The electric motor has a relatively large mass and it is necessary to rigidly connect the end of the electric motor from which the drive shaft exits to the housing. Since the electric motor in addition to its large mass also has a relatively large length, it follows that act on the mounting area between the engine and housing large leverage. In order to avoid these leverage forces, it would be fundamentally possible to rigidly connect the second end of the electric motor, which is opposite the first end, to the housing. However, due to always existing manufacturing tolerances would follow from this that it could lead to tension in the transmission, which would lead to noise and performance losses.
According to the invention, a holding element is provided, which connects the second end of the electric motor to the housing, wherein this holding element has at least one elastic element, so that the second end of the electric motor can be deflected under deformation of the elastic element against the housing. This elastic element compensates for manufacturing tolerances and yet significantly reduces the lever forces that occur.
Preferably, the elastic element is designed as an elastic ring, in particular made of an elastomer, which encloses a portion of the second end of the electric motor.
Further preferably, the elastic ring on a progressive damping rate, whereby on the one hand, the manufacturing tolerances are compensated at rest with little force and under load, ie when a deflection of the electric motor relative to the housing, a strong damping of the movement of the second end occurs, whereby the lever forces at the first end are correspondingly limited.
Further preferred embodiments will become apparent from the other dependent claims and from the embodiment now shown in more detail with reference to the figures.
The invention will now be explained in more detail using an exemplary embodiment with reference to the figures. Hereby show:
1 A highly schematic cross-sectional view of a retractor,
2 a reel in a first plan view,
3 the reel 2 in a view from direction R1,
3a the detail D off 3 .
4 the reel from the 2 and 3 in a plan view from direction R2,
5 a section along the plane BB 3a and
6 a damping curve of the elastomeric ring.
The 1 shows a highly schematic cross section through a reel, with only the components of interest here are shown and the usually still existing components, such as blocking device and pyrotechnic tensioner, are not shown.
The reel has a housing 10 in which a Gurtaufwickelwelle 15 is rotatably mounted, what this the two end walls 12a . 12b of the housing 10 durchströßt. One end of the belt take-up shaft 15 is via gear wheels 18 with the drive shaft 25 an electric motor 20 connected so that the belt take-up shaft 15 from the electric motor 20 can be driven. The first end 20a of the electric motor 20 , from which the drive shaft 25 sticks out, is rigid with the case 10 connected, including a flange 22 at the front of the electric motor 20 serves. It is in particular provided, the flange 22 with the housing 10 to screw (not shown in detail).
With the housing 10 is still rigid a first section 31 a holding element 30 connected, this first section 31 is rigid and preferably made of the same material as the housing, in particular made of steel. The first paragraph 31 of the holding element 30 extends substantially to the second end 20b of the electric motor 20 , In this place is in the first section 31 an elastic ring 32 in the first section 31 taken, which is the second end 20b of the electric motor 20 encompasses and positively connected with this. first section 31 and elastic ring 32 together form the retaining element 30 , The elastic ring 32 is preferably made of an elastomer, such as NBR (nitrile butadiene rubber).
The holding element 30 holds the second end 20b of the electric motor 20 in relation to the housing 10 , wherein the holder is not completely rigid. Preferably, the elastic ring 32 a progressive damping rate, as exemplified in 6 is shown. As a result, the force which the retaining element 30 to the second end 20b of the electric motor 20 permanently due to possibly existing manufacturing tolerances, low, but increases with increasing deflection, so that a strong deflection is prevented due to acceleration forces occurring.
The 2 to 5 show a concrete embodiment with greater detail: The 2 shows a complete reel 5 , The belt retractor 5 has a housing in which the Gurtaufwickelwelle 15 is rotatably mounted. The housing comprises a base plate 40 , from the first end wall 12a and second end wall 12b extend. In the two end walls 12a . 12b is the belt take-up shaft 15 immediately stored. One recognizes a tightening tube 50 with a pickup section for a propellant 52 as part of a pyrotechnic pretensioner device.
Parallel to the belt winding shaft 15 extends the electric motor 20 and is with its first end 20a rigid with the housing 10 connected, namely screwed. From the base plate 40 extends a tab 42 , on which in turn the retaining plate 34 is attached. This holding plate 34 has an opening into which the elastic ring 32 is inserted. Through this elastic ring 32 pushes the second end 20b of the electric motor 20 how to do this in particular 5 extracts. This results in a positive connection between the electric motor 20 and elastic ring 32 as well as between elastic ring 32 and holding plate 34 , The retaining element is thus in this embodiment of the retaining plate 34 as a stiff section and the elastic ring 32 formed as an elastic portion.
Between electric motor 20 and holding plate 34 there is an annular gap with the width s (s. 5 ), which passes through the elastic ring 32 is completed. How to get the 5 further removes, lies the electric motor 20 at a lower portion of the elastic ring 32 on while holding plate 34 at an upper portion of the elastic ring 32 is applied. Due to this geometry results in a damping curve, as in 6 is shown, namely a progressive damping curve. The elastic ring 32 is under pretension, giving a centering force to the second end 20b of the electric motor 20 already at rest (Δs = 0) prevails. The characteristic increases progressively, which means that even at high acceleration forces the second end 20b of the electric motor 20 only slightly deflected, resulting in correspondingly small forces on the attachment of the first end 20a of the electric motor 20 on the housing 10 leads. Nevertheless, those are due to the retaining element 30 caused forces at rest low, so that no damage to the gearbox is to be feared. It would also be possible to choose a characteristic which increases progressively, but passes through the zero point, so that the elastic ring in the idle state exerts no force on the second end of the electric motor. However, the characteristic curve selected here with Vopr voltage has the advantage that even with small deflections a counterforce occurs.
LIST OF REFERENCE NUMBERS
- first end wall
- second end wall
- longitudinal connection
- belt winding shaft
- Transmission gears
- electric motor
- first end
- second end
- drive shaft
- retaining element
- first section
- elastic ring
- Retaining plate
- Pickup section for propellant