WO2016113124A1

WO2016113124A1 - Belt tightener for a safety belt system

Info

Publication number: WO2016113124A1
Application number: PCT/EP2016/000031
Authority: WO
Inventors: Adrian Landbeck; Thomas Mödinger; Alexander WAIDMANN; Andreas Pregitzer
Original assignee: Trw Automotive Gmbh
Priority date: 2015-01-15
Filing date: 2016-01-11
Publication date: 2016-07-21
Also published as: DE102015000203A1; CN107257754A; DE102015000203B4

Abstract

A belt tightener for a safety belt system comprises a drive device having a tightener tube (10) and a substantially deformable power transmission element (12) which is guided inside the tightener tube (10) and engages a rotatable drive element during belt tightening. According to the invention, at least part of the surface of the power transmission element (12) and/or at least part of the inner surface of the tightener tube (10) is structured and covered with a lubricant.

Description

Belt tensioner for a safety belt system

The invention relates to a belt tensioner for a safety belt system, comprising a drive device having a tensioner tube and a guided in the tensioner, substantially deformable force transmission element, which engages during a tightening operation in engagement with a rotatable drive element.

A belt tensioner is used to reduce certain influences in a restraint case, which have a negative effect on the restraint of the vehicle occupant, before the forward displacement of the vehicle occupant and possibly the use of a force limiting device begin. These influences include the so-called Filmspuleffekt (loosely on the belt reel rolled up webbing) and the beltless (not tight against the vehicle occupant webbing). The belt tensioner reduces belt slack and the film spooling effect within a very short time by tautening the belt. The vehicle occupant can thus participate early in the vehicle deceleration, and the conditions for the subsequent use of the force limiting device are optimized.

From DE 10 2006 031 359 A1 a belt tensioner of the type mentioned is known. The power transmission element used therein is substantially deformable and guided in a space-constrained torture tube. After activation of the pyrotechnic drive device, the force transmission element is replaced by the gas released by the curved

CONFIRMATION COPY Strafferrohr driven so that it acts on a rotatably mounted drive wheel, which is coupled to the axis of a belt retractor. The substantially deformable material of the power transmission element advantageously ensures that a damped Einsteuerung the power transmission element takes place at the drive and a high torque transmission is ensured.

As with all technical devices, there are also unwanted effects in belt tensioners, which lead to differences between supplied energy and usable energy. This circumstance is generally described by the term efficiency. On the one hand requires the functionality of a belt tensioner, which is triggered only once in an accident (retention case) - unlike a continuously operated machine - in view of the amount of available drive energy is not particularly high efficiency. On the other hand, an improved efficiency in a belt tensioner drive, however, bring benefits in that in the case of release of the belt tensioner functionally relevant components and connections are less heavily loaded and thus can be designed easier and cheaper. This means that either the necessary drive energy can be reduced (at the same power of the belt tensioner) or the performance of the belt tensioner can be increased (with the same drive energy). In addition, a combination of both measures is possible. Increasing the efficiency but not only has positive effects in terms of the intended normal operation of the belt tensioner (ignition in the vehicle in an accident), but also in safety terms in the case of improper use of the belt tensioner (ignition during production, transport, etc. ).

DE 10 2006 031 359 A1 proposes, in the case of a belt tensioner of the type mentioned above, to provide a medium, in particular a lubricant, at a location which coincides with the propellant gas generated by the pyrotechnic drive device and / or with an element displaced by the propellant gas in the pretensioner tube communicates. This measure has the sole purpose of reducing the risk of flame formation in a cost-effective manner, based on the knowledge that a cooling or a reduced increase in temperature of the propellant gas generated by the gas generator can be achieved by the targeted use of a lubricant. According to one concrete embodiment of this known belt tensioner is arranged in the tension between a gas generator and the force transmission element, a cylindrical sealing element which seals a pressure chamber formed between the gas generator and the sealing element and has a recess in the form of a circumferential groove, which is opposite to the inner wall of the tensioner tube. In this groove, the flame-retardant lubricant is introduced, so that it is not in direct flow communication with the gas released from the gas generator pressure gas, but is heated by this (indirectly) above the flow temperature. DE 10 2014 200 995 A1 proposes, in a basically similar belt tensioner, to provide the power transmission element with one or more lateral cuts in order to increase the flexibility of the power transmission element. This is to ensure that the power transmission element can be easily pressed by a highly curved tension pipe. The incision depth should preferably be greater than half the diameter of the force transmission element, so that the incision cuts through the middle of the force transmission element.

Object of the present invention is to provide a belt tensioner of the type mentioned with a reduced drive loss. In particular, the advantages mentioned in terms of functionality and design should be made possible by increasing the efficiency of the belt tensioner drive.

This object is achieved by a belt tensioner having the features of claim 1. Advantageous and expedient embodiments of the belt tensioner according to the invention are specified in the subclaims.

The belt tensioner according to the invention for a safety belt system comprises a drive device which has a tensioner tube and a substantially deformable force transmission element guided in the tensioner tube, which engages with a rotatable drive element during a tightening process. According to the invention, at least a part of the surface of the force transmission element and / or at least a part of the inner surface of the tensioner tube is structured and covered with a lubricant. The invention is based on the recognition that a lubricant only optimally unfolds, if it can be kept reliably, especially in the areas that are the most contact-contaminated. In the belt tensioner according to the invention, the structured surface (s) ensure that a reservoir for the lubricant is available in the long-term at the required points, and that the lubricant can not be displaced there even under load.

A structured surface in the sense of the invention does not mean a surface which is smooth or has only a slight surface roughness. Rather, the structured surface has a multiplicity of substantial elevations and / or depressions compared to a smooth reference surface, so that a sufficient amount of lubricant can always be kept ready in the lubricant receptacles created in this way. Already during the application of the lubricant ensures that the lubricant can not retreat to individual points, but evenly distributed over the structured surface area and remains in this even distribution when the power transmission element is inserted into the tensioner tube. If it then comes later to a case of restraint, thanks to the displacement-inhibiting depressions and / or elevations on the surface of the force transmission element and / or the tensioner tube ensures that the lubricant is available throughout the tightening process at the heavily loaded areas and especially there its effect unfolded.

The depressions and / or elevations on the surface of the force transmission element have a small depth or height in comparison to the diameter of the force transmission element; in particular, the depressions in no case extend to the middle of the force transmission element.

The depressions or elevations may be distributed over the entire surface or at least over a substantial part of the surface. But it is also possible to provide a structure only in certain surface areas, preferably at the most heavily loaded areas.

The structured surface may have regular and / or irregularly arranged depressions and / or elevations. While one Regular structure is usually easier to produce by machine, an irregular structure can contribute to a better statistical distribution of the lubricant.

The same applies to the provision of uniform or non-uniform recesses and / or elevations on the surface.

The force transmission element is advantageously elongated, its length being a multiple of its width. In a particularly advantageous manner, the force transmission element is cylindrical, whereby here too the length is a multiple of its diameter. In particular, only one force transmission element can be used that engages with the rotatable drive element. If the rotatable drive element is designed as a drive pinion, the force transmission element or the respectively acting force transmission element successively engages with a plurality of successive teeth. Thus, such a power transmission element differs for example from drive balls or individual mass elements, chain links or the like, which interact in each case with exactly one tooth or an engagement pocket of a rotatable drive element.

According to a particular embodiment of the invention, at least some of the recesses are formed as grooves, which preferably extend substantially perpendicular to the longitudinal direction of the force transmission element. The grooves may extend over the entire circumference of the power transmission element or over only a portion thereof.

An advantageous development of the invention provides that the force transmission element is formed structured in its interior. This does not mean that individual depressions reach far into the interior of the force-transmitting element, but that the superficial depressions are in connection with a structure of a plurality of small cavities located further in the interior. This refinement can be achieved, in particular, in that at least one region of the force transmission element is made porous. Thanks to the porous structure can also the interior of the power transmission element be mixed with lubricant. The deformable force transmission element is then comparable to a sponge capable of absorbing and releasing lubricant.

In general, a lubricant containing a grease, an oil, graphite and / or molybdenum disulfide is suitable for the above purposes.

Further features and advantages of the invention will become apparent from the following description and from the accompanying drawings, to which reference is made. In the drawings show:

FIG. 1 shows a sectional view of a drive device for a belt tensioner shortly after its activation;

FIG. 2 shows the drive device from FIG. 1 at the end of the tightening process;

- Figure 3 is a sectional view of the tensioner tube and the power transmission element of the drive device of Figure 1;

- Figure 4 is an exemplary sectional view of a Strafferrohrabschnitts and a power transmission element in the initial state;

- Figure 5 the Strafferrohrabschnitt and the power transmission element of Figure 4 under the action of force;

FIG. 6 shows a perspective view of a power transmission element according to the prior art; - Figure 7 is a perspective view of a force transmission element according to the invention according to a first embodiment with an enlarged detail;

- Figure 8 is a perspective view of a portion of a force transmission element according to the invention according to a second embodiment; - Figure 9 is a perspective view of a portion of a force transmission element according to the invention according to a third embodiment;

- Figure 10 is a perspective view of a portion of a force transmission element according to a fourth embodiment of the invention; FIG. 11 shows a perspective view of a section of a force transmission element according to a fifth embodiment of the invention;

FIG. 12 shows a perspective view of a section of a force transmission element according to a sixth embodiment of the invention; and FIG. 13 shows a perspective view of a section of a force transmission element according to a seventh embodiment of the invention.

FIG. 1 shows a drive device of a belt tensioner for a belt retractor. The drive device has a power transmission element 12 which is displaceably arranged in a tensioner tube 10. The force transmission element 12 consists of a substantially deformable material.

At a first end 14 of the tensioner tube 10, a pressurized gas 16 can be provided by a gas generator (not shown) in a section of the tensioner tube 10 serving as a pressure chamber. The second end 18 of the tensioner tube 10 is directed to the external teeth of a rotatably mounted drive wheel 20, which is coupled to a belt reel of the belt retractor (not shown).

Between the compressed gas 16 and the force transmission element 12, an elastic sealing element 22 is arranged, which is also displaceable in the tensioner tube 10. The sealing element 22 abuts the force transmission element 12, but it can also be provided a small distance. The sealing element 22 holds the compressed gas 16 on the side facing away from the force transmission element 12 side of the tensioner tube 10th

In the case of restraint, the pyrotechnic drive device is activated, and the gas generator generates the compressed gas 16, which expands in the pressure chamber located between the gas generator and the sealing element 22. As a result, acting as a piston sealing element 22 in the tensioner tube 10 is subjected to a high pressure and pushes the power transmission element 12 through the tensioner 10. The power transmission element 12 exits through the second end 18 of the tensioner tube 10 and comes with the drive wheel 14 into engagement. As a result, the drive wheel 14 is set in a rotational movement. The drive wheel 14 in turn puts the coupled to the drive wheel 14 Belt reel in a rotational movement in Gurtbandaufwickelrichtung, and it is rolled webbing on the belt reel. The final state of the drive device after its activation and ended tensioning process is shown in FIG.

In any belt tensioner that works on this principle, regardless of the shape of the tensioner tube 10, the drive force introduced at the first end 14 (drive side) is greater than the usable drive force at the second end 18 (driven side), as indicated in FIG. The losses are primarily due to friction between the power transmission element 12 and the tensioner tube 10 and by the elastic and plastic deformation of the force transmission element 12th

To reduce the friction losses between the power transmission element 12 and the tensioner tube 10, a lubricant is used, which may be liquid or solid. Examples of such lubricants are grease, oil, graphite and molybdenum disulfide. A comparison of Figures 4 and 5, showing the power transmission element 12 in the tensioner tube 10 once in the non-activated state (Figure 4) and once in the activated state (Figure 5) of the drive device, can be seen that the deformable force transmission element 12 under the action of the driving force not evenly applied to the inner surface of the tensioner tube 10. Depending on the geometry of the tightening tube 10, there are areas in which the contact is more pronounced than in other areas in which in some cases even no contact exists at all.

This results in conventional belt tensioners of this type to an uneven distribution of the lubricant. In particular, at the heavily loaded contact points, the lubricant is displaced due to the high contact forces and therefore can not unfold its effect there optimally.

FIG. 6 shows, with regard to the special force transmission elements 12 described below, first of all a conventional, cylindrical, deformable force transmission element 12 in the uninstalled state. The surface of this force transmission element 12, in particular the lateral surface, is smooth. By contrast, FIG. 7 shows a force transmission element 12, in which the surface is largely not smooth, but structured. Intentionally introduced depressions and / or elevations allow a very uniform distribution of the lubricant over the thus structured surface area. As a result, the effect of the lubricant during the tightening process is fully unfolded. Despite the occurrence of large forces, the lubricant is not displaced by the contact areas, ie it remains effective even at the heavily loaded areas.

The structure of the surface of the power transmission member 12 also acts as a reservoir for the lubricant. In the structured areas, a supply of lubricant can be stored much better than on a smooth surface. Thus, the lubrication is maintained even if the load on the power transmission element 12 under load occurs and it comes to the surface to detachment of particles.

In the embodiment shown in FIG. 7, with the exception of the end sections, the entire surface of the force transmission element 12 is provided with regularly arranged, circular recesses 24, as can be seen in particular in the detailed enlargement of FIG. The recesses 24 do not penetrate too far into the power transmission element 12, at least not far to the middle.

Figures 8 and 9 show by way of example two further embodiments of the power transmission element 12, in which a plurality of regularly arranged, uniform recesses 24 are provided. In the embodiment of Figure 8, the recesses 24 are arranged offset from one another and have a substantially rectangular shape. In the embodiment of Figure 9, the recesses 24 are formed as grooves which are spaced in the longitudinal direction of the power transmission element 12 and rotate perpendicular to the longitudinal direction of the force transmission element 12.

Figures 10, 11 and 12 show by way of example three further embodiments of the power transmission element 12, in which irregularly arranged, non-uniform depressions 24 and / or elevations are provided. FIG. 13 shows a particular embodiment in which practically the entire force transmission element 12, including its interior, is provided with a structure, wherein the structure may be uniform or non-uniform. Such a structure of the force transmission element 12 can be realized for example by a targeted introduction of pores. In any case, here the entire structure of the deformable power transmission element 12 is capable of receiving and releasing lubricant, much like a sponge.

The described measures, which all improve the distribution and the holding of the lubricant and thereby reduce the friction losses, can of course be combined with each other in a suitable manner.

As well as the surface of the force transmitting member 12, additionally or alternatively, the inner surface of the tightening tube 10 (or certain portions thereof) may be structured with regularly or irregularly arranged, uniform or irregular depressions and / or elevations. With regard to the distribution and the (long-term) holding of the lubricant, the same applies as that previously said for the structured surface of the force transmission element 12.

Reference number list Tailpipe

Power transmission element

first penalty tube end

compressed gas

second penalty tube end

drive wheel

sealing element

wells

Claims

claims

A belt tensioner for a safety belt system, comprising a drive device having a tensioner tube (10) and a substantially deformable force transmission element (12) guided in the tensioner tube (10), which engages with a rotatable drive element during a tightening operation,

characterized in that at least a part of the surface of the force transmission element (12) and / or at least a part of the inner surface of the tensioner tube (10) is structured and covered with a lubricant.

2. A pretensioner according to claim 1, characterized in that the structured surface has regularly arranged depressions (24) and / or elevations.

3. A pretensioner according to claim 1 or 2, characterized in that the structured surface has irregularly arranged depressions (24) and / or elevations.

4. A pretensioner according to one of the preceding claims, characterized in that the structured surface has uniform depressions (24) and / or elevations.

5. Belt tensioner according to one of the preceding claims, characterized in that the structured surface non-uniform depressions

(24) and / or elevations.

6. A pretensioner according to one of the preceding claims, characterized in that at least some of the recesses (24) are formed as grooves, which extend preferably substantially perpendicular to the longitudinal direction of the force transmission element (12).

7. belt tensioner according to one of the preceding claims, characterized in that the force transmission element (12) is formed structured in its interior.

8. belt tensioner according to claim 7, characterized in that the force transmission element (12) has at least one porous region.

9. A pretensioner according to one of the preceding claims, characterized in that the lubricant contains a fat, an oil, graphite and / or molybdenum disulfide.