Patent Application
20060192418
This is a utility application that claims Priority benefit, under 35 USC §119 (a), to German Patent Application No. 102005005889.2, filed Feb. 9, 2005, which application is incorporated herein by reference.
The invention relates to a roller guide for a vehicle-seat oscillation system having a scissor-type guide, which scissor-type guide has a scissor-type cross tube which, at each of its two ends, has a respective pin as a hub, there being rotatably disposed on at least one of the pins a first roller, of plastic, which runs in a U-profile running rail and which is of such a diameter that it runs with little play in the running rail.
Such roller guides are sufficiently well known as vehicle seat bearings in the case of scissor-type oscillation systems. The rollers in this case are produced as injection-moulded parts from a plastic. The rollers run in metal running rails having a U-shaped profile. In the case of heavy loading, for example in the case of a rear-end collision, these rollers frequently break. This then regularly results in relatively large deformations of the vehicle seat and, in some cases, as consequential damage, even in the complete failure of individual components or of the vehicle seat as a whole.
In order to avoid the disadvantages described above, the rollers are realized as a metal part or as a plastic solid-material part, for example as a turned part. Although this does prevent breakage of the rollers, the materials and the production process are nevertheless substantially more expensive.
It is therefore the object of the invention to present a roller guide which, on the one hand, is inexpensive to produce and, on the other hand, even in extreme situations does not lead to deformations of the vehicle seat as a result of a major deformation or possible breakage of a roller.
The object is achieved by a roller guide having the features of claim 1. Due to the fact that, in addition to the first plastic roller, there is also rotatably mounted on the pin a disc whose hardness is significantly greater than the hardness of the first roller, even in the case of a deformation of the first plastic roller in the event of high loading no deformation of the vehicle seat can occur, since the harder disc assumes the guidance function within the running rail. In the context of this application, the term hardness means the material strength. Its ratio is normally at least 1:5. In the case of the preferred use of a plastic roller—for example having a material strength of 60 N/mm2—and of a small steel plate—for example having a material strength of 500 N/mm2—this ratio is between 1:8 and 1:10. The ratio may, however, be greater than 1:10, depending on the materials used. The same applies if, instead of the disc, a small plate is used, its height being slightly less than the diameter of the first roller. In the context of this application, the term slightly smaller diameter means that, upon compression of the roller in the case of normal operating load, the difference in the two diameters is within the range of the deformation. Depending on the materials, this difference lies within a range from 0.2-2.0 mm; it could be greater than said range, however, in the case of appropriate materials. In this case, the small plate, as a safety element, offers even greater safety, since it bears flat on the running rail. Provided that the first roller is only slightly deformed-in particular, is not broken—the disc, owing to its slightly smaller diameter, or the small plate, owing to its slightly lesser height, is not in contact with the running rail, such that, in this case, the running characteristics are unchanged compared with the running characteristics known from the prior art. Only in the event of a breakage or significant deformation of the first roller, composed of plastic, does the disc or the small plate assume the function of said first roller.
A small plate, within the meaning of the invention, is to be understood to include both rectangular small plates and small plates of any contour, such as, for example, a lozenge, a triangle, an n-polygon, a semicircle or an ellipse. In this connection, the height of such a small plate—when the small plate is in the mounted position on the pin—is to be understood to be the greatest distance between respectively two points on the contour face that are vertically over one another. The width in this case may also be greater than the diameter of the roller, particularly if the small plate is realized as a rectangle. In order to prevent rattling, such a small plate may be coated, for example with a paint or an appropriate plastic.
An advantageous development of the invention makes provision whereby the disc or the small plate is disposed only on that end of the scissor-type cross tube that is located on the side of an upper connection point of a seat-belt mounted on the seat. Since the loading is greater on the stated side, deformation of the first roller occurs here first, said deformation being taken up by the disc or by the small plate. The other side is only affected in the case of application of a much greater force.
A further advantageous development of the invention makes provision whereby respectively a first roller and a disc or small plate are disposed at each of the two ends. This increases the safety compared with the single-sided realization, since the other side is also secured.
The disc or the small plate is preferably composed of a steel. As a result, the disc or small plate is extremely stable, and also cannot be destroyed by high loads, such that there can be no consequential damage to the vehicle seat. Moreover, such a disc or such a small plate can be produced very easily, for example by a simple stamping process.
A further advantageous development of the invention makes provision whereby there is rotatably disposed on the pin, between the end of the scissor-type cross tube and the disc or small plate, a second roller, of plastic, whose diameter is slightly greater than the diameter of the disc or the height of the small plate respectively. As a result, even in the case of a major deformation or a breakage of the one roller—irrespective of whether it be the first or the second roller—a longer service life of the roller guide is achieved, since said roller guide can still be moved on the remaining roller within the running rail. Only if both rollers are defective does the disc or small plate of significantly harder material again become operative and assume the function of the two rollers, such that there is no consequential damage to the vehicle seat in any case.
A further advantageous development of the invention makes provision whereby the disc or the small plate bears fully on the first roller and bears flat on the end of the scissor-type cross tube, or fully on the second roller. It is thereby possible for the disc or the small plate to be realized as a very thin disc or small plate, since buckling of the disc or small plate is prevented by their bearing on the first roller and on the second roller, or on the end of the scissor-type cross tube. In this case, the thickness of the disc or small plate may even be reduced to such an extent that it is in the range from 1 to 5 mm, being preferably 2 mm in the case of an embodiment in steel.
A further advantageous development of the invention makes provision whereby the disc is firmly connected to one of the rollers. This enables one less part to be mounted on the hub, resulting in simplified assembly. For a small plate, this is also possible in the case of an appropriate contour. Thus, in the case of an n-polygon with a large number of sides, a close approximation to the circular form is achieved, and the small plate does not project over the roller. This would not apply in the case of a triangle, since the edge length of the triangle—in the case of the height being only slightly less than the diameter of the roller—would be so long that the small plate would project over the roller.
A further advantageous development of the invention makes provision whereby the disc is integrated into one of the rollers, particularly as an insert in an injection-moulded part. Such an integrated part can be produced very easily and inexpensively with, at the same time, a high quality as a mass-produced article. The above statements in this paragraph also apply to small plates.
The first roller and/or the second roller is preferably realized as an injection-moulded part. The plastic parts that are known from the prior art, and that can be produced very easily and inexpensively, can thus be used for these two rollers.
Further advantageous developments of the invention are explained more fully with reference to the two exemplary embodiments represented in the figures, wherein:
The first exemplary embodiment represented in
Realized at the end 2 of the scissor-type cross tube 1 is a pin 3, which serves as a hub. Rotatably mounted on this pin 3 are two elements, namely a first roller 6 and a disc 7. In this case the disc 7 is located between the end 2 of the scissor-type cross tube 1 and the first roller 6.
Both the first roller 6 and the disc 7 are disposed within the U-shaped running rail 4. The U-profile is so disposed that its two limbs 5 point towards the scissor-type cross tube 1. The running rail 4 is a device known from the prior art, there being no need for more detailed reference to its design, since a person skilled in the art is familiar with said design.
The first roller 6 is produced from plastic, as an injection-moulded part. It is of a diameter which is preferably slightly smaller than the distance between the two limbs 5 of the running rail 4, such that the scissor-type cross tube 1 is guided with little friction within the running rail 4. Apart from the disc 7 additionally mounted on the pin 3—which disc 7 is described in the following in respect of both its design and its functioning—the roller guide is a roller guide, well known from the prior art, for a vehicle-seat oscillation system having a scissor-type guide.
In the exemplary embodiment represented, the disc 7 according to the invention is made from a steel. Since the disc 7 is of a significantly greater hardness than the plastic of the first roller 6, breakage of the roller 6 is to a large extent prevented, since the disc 7 assumes a portion of the load. If a breakage of the roller 6 does occur, however, the disc 7 assumes the load completely, such that there is no further damage to the seat. The further damage that occurs upon breakage of rollers 6 in the case of an accident is sufficiently well known from crash simulations, and is not explained more fully here. In order that the disc 7 can take up the load, the two limbs 5 of the running rail extend so far in the direction of the scissor-type cross tube 1 that they reach to the end 2 of said scissor-type cross tube 1. The disc 7 that is rotatably disposed on the pin 3 is thus located within the running rail 4. This design makes it possible, on the one hand, to continue to produce the first roller 6 in a very inexpensive manner and, at the same time, to ensure safety in the case of a breakage or major deformation of the first roller 6 in the case of extreme loads. In this case, the diameter of the disc 7 is made to be slightly smaller than that of the first roller 6. This, in normal operation—provided that the first roller 6 is intact—provides for a good roller guidance—known from the prior art, since in this case the disc 7 is not in contact with the limbs 5 of the running rail 4.
The disc 7 may be made very thin—in the exemplary embodiment represented, it has a thickness of only 2 mm—since buckling is prevented. In the exemplary embodiment represented, this is assured, in the direction of the first roller 6—i.e. away from the scissor-type cross tube 1—in that the entire surface of the disc 7 bears on the first roller 6. Moreover, the other surface of the disc 7 bears, in a large area, on the end 2 of the scissor-type cross tube 1, such that buckling in the direction of the scissor-type cross tube 1 is prevented. Such a thin disc 7 can be produced very inexpensively—for example, by a stamping process—but it performs its function as a protection in the case of breakage of the first roller 6 in an excellent manner.
In addition to the first roller 6, a second roller 8 is mounted on the pin 3 of the scissor-type cross tube 1. This second roller 8 is disposed between the steel disc 7 and the end 2 of the scissor-type cross tube 1. The second roller 8 has a diameter which is slightly greater than that of the first roller 6. It is likewise made from a plastic, and in this case can also be produced very inexpensively as an injection-moulded part. Since the diameter of the second roller 8 is slightly greater than that of the first roller 6 and, at the same time, one of the two limbs 5 of the running rail 4 is made shorter, in profile both rollers 6, 8 have bearing contact only on one side (the first roller 6 on the upper limb 5 and the second roller 8 on the lower limb 5), facilitating the rotary motion of the rollers 6, 8 in the case of small tolerances. This type of roller guidance has long been known in the art, and need not be explained further. Also, in the case of insertion of the disc 7 as a safety element in this type of roller guide, the diameter of the disc 7 is slightly smaller that that of the rollers 6, 8. The length of the limbs 5 is made such that, in the case of deformation or breakage of one or both rollers 6, 8, the disc 7 is located within the two limbs 5 and thus takes up the occurring loads.
In an advantageous development of the invention, provision is made whereby the disc 7 is firmly connected to the respective roller 6, 8, this facilitating assembly, since the number of parts to be assembled is thus reduced. Many known technical solutions have long been available for the nature of the design of the connection of the metal disc 7 to the plastic roller 6, 8. Said solutions need not be explained here, since they are known to the specialist in the art.
Instead of the disc 7 as a safety element, it is also possible to use a small steel plate (not shown)—particularly in the form of a rectangle—that is of a height which is slightly smaller than the diameter of the rollers 6, 8. Although this small plate cannot be firmly connected to the rollers 6, 8, or even injection-moulded into the latter—whereby the advantage of fewer components in not achieved—it nevertheless constitutes a flat bearing contact on the lower limb 5 of the running rail, resulting in improved safety. This also applies, in principle, to small plates of any contour.
In addition to the design of the second roller 8 with a diameter that is greater than that of the first roller 6, the two rollers 6, 8 may also be realized with the same diameter.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 005889.2 | Feb 2005 | DE | national |
