Description

The invention relates to an airbag module according to claim 1 , to a steering wheel with such an airbag module according to claim 10 and to a motor vehicle with such a steering wheel according to claim 1 1 . The invention described hereinafter is mainly concerned with a so-called driver airbag module being a part of the steering wheel of a vehicle. But this invention is not limited such driver airbag modules, it can also be applied to other kinds of frontal airbag modules, especially to so-called passenger frontal airbag modules. Almost every passenger car has a driver airbag module which is a part of the steering wheel of this car. This driver airbag module comprises an airbag which inflates in front of the driver in case of a frontal accident. Nowadays almost every passenger car is permanently driven by its driver meaning that the driver needs to have his hands on the steering wheel, so that the distance between the steering wheel and the driver is known within relatively small tolerances which mainly depend on the size and the habits of the driver. Usually this tolerance is in the range of about 10 to 30 cm. So, the airbag of this driver airbag module can be designed for this approximately known distance between the steering wheel and the driver. But because of the rapid development of computer systems and sensors it is very likely that in the near future motor vehicles will widely be used that can be driven manually (as current motor vehicles) or autonomously (meaning that the driver does not need to have his/her hands on the steering wheel at least in situations like driving on the motor way). In order to provide the driver with more comfort in situations when he/she does not need to touch the steering wheel for a longer time, it has been discussed to design motor vehicles (especially passenger cars) in such a way that in such situations the seat of the driver can be moved away from the steering wheel or that the steering wheel can be moved away from the d river. As a consequence the distance between the steering wheel and the driver will then be dramatically different in situations in which the driver actively drives the car compared to situations in which the car drives autonomously. Starting from this prior art it is the task of the invention to provide an airbag module which is optimised for an above described car, meaning that the airbag of this airbag module gives good and secure protection for the driver in cases in which the steering wheel is relatively close to the driver (such that the driver can have the steering wheel in hands) and in cases in which the steering wheel is relatively far away from the driver (such that the driver cannot easily touch the steering wheel).

This task is solved by an airbag module with the features of claim 1. A steering with such an airbag module is defined in claim 10 and a motor vehicle with such a steering wheel is defined in claiml .

As every airbag module, the inventive airbag module comprises a carrier (usually a housing or a part of a housing), an inflating device, and an airbag being held by said carrier and enclosing a gas space.

The airbag comprises a first part enclosing a first portion of the gas space and a second part enclosing a second portion of the gas space. The first part has a connection area that is at least indirectly permanently connected to the carrier. According to the invention an intermediate part is provided between the first part and the second part. In an initial state this intermediate part is restraint to the carrier by means of restraining means. The airbag module further comprises at least one active release means for setting the restraining means out of function. The active release means can be connected (usually electrically) to a controller of the vehicle.

This means that as long as the intermediate part is restrained at the carrier, only the second part deploys when the inflating device is triggered. This second part can basically have the size and the shape of a traditional driver airbag. If the car is in its manually drive mode and a frontal accident occurs, the inflating device is triggered but the release means is not triggered. As a consequence only the second part of the airbag deploys and for the driver there is no difference between the inventive airbag module and a traditional airbag module. If the car is in its au- tonomous drive mode and a frontal accident occurs, the inflating device and the release means are triggered. As a consequence the first part and the second part of the airbag deploy and the airbag gains depth so that the larger distance between the steering wheel and the driver is compensated. In this case, the second part of the airbag is“on top” of the first part. The impact surface is the same as in the manual drive mode. This means that the driver is always hitting the second part of the airbag.

There is a variety of possibilities of how to design the restraining means and the release means. Preferred ones are defined in the sub-claims and/or described in detail below. In some cases an element can be both: a part of the restraining means and a part of the release means.

For safety reasons it is preferred that the restraining connection between the intermediate area and the carrier is only released if the release means are actively triggered. So in case of a failure only the second part of the airbag deploys.

The first part and/or the second part can be provided with at least one shaping tether and/or with at least one active or passive ventilation device. Usually at least one ventilation device is provided in the second part of the airbag.

It is preferred to design the two parts as two airbags being connected to one another. In this case there is an overflow opening between the two portions of the gas space and the border area of the overflow opening forms the intermediate part of the airbag.

Since the total volume to be filled depends on the kind of deployment (only the second part or both parts of the airbag), it is preferred to use a two-stage inflating device. The invention will now be described in detail by means of preferred embodiments in view of the figures. The figures show: Figure 1 a schematic sectional view of a first embodiment of an inventive airbag module in the resting state,

Figure 2 a plan view to the airbag module of Figure 1 from direction R1 in

Figure 1 ,

Figure 3 what is shown in Figure 1 in a first deployment state of the airbag of the airbag module,

Figure 3a a variation of the embodiment shown in Figure 3,

Figure 4 what is shown in Figure 3 in a second deployment state of the airbag,

Figure 5 a further variation of the first embodiment in a representation according to Figure 3,

Figure 6 basically what is shown in Figure 5 when the airbag module is a part of a steering wheel,

Figure 7 what is shown in Figure 6 in a state according to Figure 4,

Figure 8 a second embodiment of the invention in a representation and a state according to Figure 1 ,

Figure 9 what is shown in Figure 8 in a first deployment state (like Figure 3),

Figure 10 what is shown in Figure 9 in a second deployment state of the airbag, Figure 11 a third embodiment in a view and a state according to Figures 1 and

8

Figure 12 a detail of Figure 11 , also in a schematic representation,

Figure 13 a plan view from direction R2 in Figure 12,

Figure 14 the airbag module of Figure 11 placed in a steering wheel in a first deployment state,

Figure 15 what is shown in Figure 14 in a second deployment state,

Figure 16 a fourth embodiment of the invention in a view and in a state accord- ing to Figure 1 , and

Figure 17 an outer collar used in the fourth embodiment in a schematic plan view.

Figures 1 to 4 show a first embodiment of an inventive airbag module 10. As every airbag module the inventive airbag module 10 comprises an airbag 50, a carrier 12 to which the airbag is directly or indirectly attached and an inflating device, here in form of an inflator 22 (for example a gas generator). The carrier 12 of the embodiment shown is in form of a housing having a housing floor 14 and a side wall 20, but it needs to be mentioned that the carrier could for example exclusively be comprised of a base plate or similar. Since the carrier is in form of a housing, sometimes the term“housing” is used instead of the term“carrier”. Usually a cover is provided (not shown in the drawings) such that the housing (or other carrier) and the cover together define an accommodation space in which the airbag 50 is accommodated as long as the inflator 22 is not triggered.

The carrier 12, namely the housing floor 14, has a central opening 16 through which the main body 23 of the inflator 22 extends. A flange 24 extends from the main body 23 of the inflator 22 and is located on the inside of the housing. As is known in the prior art the flange 24 is used for attaching a connection area 64 of the airbag 50 to the carrier 12. Of course other connection means for connecting this connection area 64 to the carrier could also be used.

The airbag 50 is comprised of the first part 60 extending from the connection area 64 and a second part 70 extending from the first part 60 at its end remote from the connection are 64. As can especially be seen from Figure 4 the first part 60 defines a first chamber enclosing a first portion P1 of the gas space and the second part 70 defines a second chamber enclosing a second portion P2 of this gas space. As can also best be seen in Figure 4 the two portions P1 , P2 of the gas space are in fluid connection by means of an overflow opening 72 which is surrounded by an intermediate part 74 of the airbag 50 which could also be referred to as border area. This intermediate part 74 can consist of ordinary airbag materi- al only or it can be provided with additional elements such as additional layers in order to give this area an enhanced robustness. A plurality of tethers 76 extend from this intermediate part 74 through openings 18 in the carrier 12. Each tether 76 has an annular end 76a and a closed rope 30 extends through these annular ends 76a. The annular ends 76a and the rope 30 are located on the outer side of the housing. So, as long as the rope 30 is intact, the intermediate part 74 is restrained to the carrier by means of the tethers 76 and the rope 30, so the tethers 76 and the rope 30 form the restraining means. This is shown in Figures 1 to 3.

Figure 2 shows that a cutter 32 is provided on the outer side of the carrier 12. The rope 30 extends through this cutter 32. In this embodiment the cutter 32 forms the release means being connected (usually electrically) to a controller of the vehicle (not shown in the drawings). On a signal from this controller the cutter 32 cuts the rope 30 so that then the restraining connection between the intermediate part 74 of the airbag 50 and the carrier 12 is destroyed.

So, two deployment states can be realised, namely a first deployment state in which the rope 30 is uncut, only the second part 70 of the airbag 50 deploys and the first part 60 is restrained, because the intermediate part 74 is restrained to the carrier 12.

The second part 70 of the airbag 50 can be designed and shaped as a traditional driver airbag so that its retraining function in a manual drive mode of the vehicle is identical to nowadays driver airbags. Although not shown, active of passive ventilation devices can be provided. Further, shaping tethers for shaping the second part of the airbag 50 can be present. Especially shaping tethers can be provided which connect an impact surface of the second part 70 with the intermediate part 74 (please see Figure 3a).

In the case that the steering wheel is remote from the driver (when the car is in an autonomous drive mode) the vehicle controller triggers the cutter 32 in case of an accident, such that the restraining connection between the intermediate part 47 and the carrier 12 is set out of function, such that the first part 60 of the airbag 50 can deploy from the carrier 12. This is shown in Figure 4. One can see that in this case the second part 70 of the airbag is“on top” of the first part 60 so that the depth of the airbag 50 is enhanced relative to the first deployment state shown in Figure 3. Although not shown in Figures also the first part 60 of the airbag 50 can comprise shaping tethers and/or active or passive ventilation devices.

Figure 5 shows a further variation to the first embodiment described above. In order to ensure that at least most of the gas flows directly into the second portion P2 of the gas space as long as the first part 60 of the airbag is not deployed, a hose 79 extends from the intermediate part 74 towards the housing floor 14. This hose functions as a gas guiding element.

Figures 7 and 8 show the airbag module 10 of Figure 5 mounted into a steering wheel body 5 (which is the main application of the invention).

Figure 8 shows a second embodiment. The difference to the first embodiment is that the restraining means for the intermediate part 74 of the airbag 50 and the release means differ from the restraining means and the release means of the first embodiment. The principle idea is of course the same. In this second embodiment the intermediate part 74 is in form of relatively stiff ring 78, or such a ring 78 is connected to the intermediate part 74. Preferably one side of the ring 78 is attached (for example glued) to the airbag 50. At least one (preferably three) hold- ing element 34 is provided to restrain the ring in the position shown in Figure 8 as long as only the second part 70 of the airbag 50 is to be deployed. These holding elements 34 serve as restraining means and as release means connected to a (not shown) controller. In the example embodiment shown in Figure 8 these holding elements 34 are comprised of a cylinder 36 containing a pyrotechnical load 38 and a movable restraining element 35 which is here in form of a piston being located inside the cylinder and a rod extending from this piston through an opening of the cylinder. As long as it is intended not to deploy the first part 60 of the airbag the ends of these rods are placed above the ring 78 (see Figures 8 and 9). When the pyrotechnic loads 38 are ignited the pistons and the rods are moved outwardly such that the rods are then laterally offset of the ring 78 such that the ring 78 (and thus the intermediate part) is free and the first part 60 of the airbag can deploy.

Figures 1 1 to 13 show a third embodiment which is similar to the first embodiment. As in the first embodiment a rope 30 is connected to the intermediate part 74, for example by means of several short tethers. In contrast to the first embodiment the rope is not located outside the housing. A diffusor 26 with a step and a holding device 40 are provided. Most of the rope 30 is placed under the step of this diffusor 26, but one section extends around a de-attachable second part 44 of the holding device 40 whose first part 42 is permanently attached (either directly or indirectly) to the carrier 12. This holding device 40 contains a small pyrotechnic load and on ignition of this pyrotechnic load the second part 44 is de-attached from the first part 42. The geometry is chosen such that as long as a section of the rope 30 extends around the second part 44 attached to the first part 42, the rope cannot be pulled over the step and so it restrains the intermediate part 74 (this situation is shown in Figures 1 1 , 12 and 13). When the second part 44 is de- attached from the first part 42 the rope 30 becomes lose and can then not be restrained anymore by the step of the diffusor and thus the intermediate part 74 loses its connection to the carrier. This situation is shown in Figure 15. So, as in the second embodiment, the holding device is both: a part of the restraining means and a part of the release means.

Figures 16 and 17 show a fourth embodiment. Here the intermediate part 74 is clamped between two elements forming the restraining means, namely an inner conical holding part 24b and an outer holding part in form of an outer collar 46. The inner conical holding part 24b is a part of the flange 24 which has additionally a mounting part 24a. The conical holding part 24b can additionally serve as a deflector or diffusor. The outer collar 46 has a conical inside surface 46a. In the ini- tial state this outer collar 46 is closed, but it can be opened at at feast one place. In the embodiment shown a pyrotechnic squib 48 placed inside a bore in this outer collar 46 is provided. This pyrotechnic squib 48 serves as release means. Because of the conical geometry the intermediate part 74 cannot be pulled out because it is clamped between the inside conical element (conical holding part 24b) and the outer conical holding part (outer collar 46). Of course this clamping does not take place anymore when the outer collar 46 is open at one end and so by igniting the pyrotechnic squib 48 the intermediate part 74 can be de-attached from the carrier 12. One advantage of this embodiment is that in the initial state the first portion P1 of the gas space is perfectly sealed from the second portion P2.

List of reference numbers

5 steering wheel body

10 airbag module

12 carrier

14 housing floor

16 central opening

18 openings for tethers

20 side wall

22 inflator

23 main body

24 flange

24a mounting part

24b conical holding part

26 diffusor with step

30 rope

32 cutter

34 holding element

35 movable restraining element (rod connected to piston) 36 cylinder

38 pyrotechnic load

40 holding device

42 first part (permanently attached)

44 second part (de-attachable)

46 outer collar

46a conical inside surface

48 pyrotechnic squib

50 airbag

60 first part

64 connection area

70 second part

72 overflow opening

74 intermediate part tethera annular end ring hose