Seat track arrangements for mounting seat assemblies within vehicles are generally well known. Most arrangements provide for a seat to be moved or adjusted in forward and rearward directions within a vehicle. Usually the seat assembly includes a mounting assembly for mounting the seat assembly to a vehicle structure.

Mounting assemblies typically include a first track member that is fixed to a vehicle structure such as the floor. A second track member is mounted for movement relative to the first track member. An adjusting mechanism is selectively operated by a seat occupant to move the second seat track to a desired position. The seat is supported on the second track so that the seat moves along with the second track as the seat occupant adjusts the seat position.

Some mounting assemblies use ball bearing members inserted between the first and second tracks to slidably support the second track relative to the first track. In known assemblies using ball bearing members, it is difficult to produce a circular profile in the seat track members to receive the ball bearings. Slight variations in the circular profile can result in amplified variations in tolerance stackup between tracks and balls and can also cause line contact between the ball bearings and the seat track members. Line contact creates a sliding effect between the ball bearings and the seat track members and can cause high adjustment effort, which is undesirable. It is preferable to have rolling contact between the ball bearings and the seat track members to improve seat adjustment effort.

Another disadvantage that can result bv using seat tracks with circular profiles for receiving ball bearings is seat track scraping. Slight variations in the circular profile can result in the second track coming into contact with the first track when the

seat is adjusted under load, i. e. when a seat occupant is sitting in the seat, the second track member can scrape alona the first track member during adjustment. This results in undesirable noise and high adjustment effort.

Accordingly. it is desirable to provide a seat track assembly that provides point contact between a bearing member and the seat track members to create a rolling effect between the seat track members and the bearing members. It is also desirable to provide a seat track assembly that maintains a clearance between the first and second track members under load to avoid seat track scraping. Finally, it is desirable to provide a seat track assembly that has improved seat track stability over known seat track assemblies.

Other objectives include providing a simplified seat track assembly that reduces the overall weight and cost of the seat assembly while maintaining durability and robustness.

SUMMARY OF THE INVENTION This invention relates to a vehicle seat assembly that is attached to the vehicle by a mounting assembly. The mounting assembly includes a first track and a second track slidable supported for movement relative to the first track. This allows the seat assembly to be adjusted forwardly or rearwardly by a seat occupant.

In a preferred embodiment of this invention, the assembly for mounting a seat within a vehicle includes a first track defining a longitudinal axis and having a first pair of sidewalls interconnected by a first base. The first pair of sidewalls each have an outwardly extending groove. A second track is supported for movement relative to the first track along the longitudinal axis and has a second pair of sidewalls spaced apart from the first pair of sidewalls and interconnected by a second base. The second pair of sidewalls each have an inwardly extending groove that is mounted opposite from the outwardly extending groove to form a pair of bearing channels between the first and second pairs of sidewalls.

The subject invention offers several advantages over prior art mounting assemblies because it provides a stable and robust mounting assembly with point contact between the bearing members and the track members to create a rolling effect.

Additionally, a stable seat track assembly is provided that maintains a clearance between the two track members under load.

These and other features and avantages of the present invention will be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side schematic view of a seat assembly mounted to a vehicle structure.

Figure 2 is a perspective view of a preferred embodiment of a mounting assembly including the subject track members.

Figure 3 is a perspective exploded view of a preferred embodiment of the track members shown in Figure 2.

Figure 4 is a cross sectional view of a preferred embodiment of a seat track assembly.

Figure SA is a cross sectional view of the outer seat track member shown in Figure 4 and including a bearing member.

Figure 5B is a cross sectional view of the inner seat track member shown in Figure 4 and including a bearing member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 1 illustrates a vehicle seat assembly 10 with a seat back 12 supported with respect to a seat bottom 14, as is well known in the art. The seat assembly 10 is mounted to a vehicle structure 16, such as a vehicle floor, by a mounting assembly, shown generally at 18. The mounting assembly 18 includes track assemblies 20 on an inboard side and an outboard side of the seat assembly 10, only the outboard side is shown in Figure 1. The terms inboard and outboard are used in this description for clarity and illustration purposes only and cannot be considered limiting.

The track assembly 20 can be used on a seat 10 that has a seat belt assembly 22 solely supported by the seat 10. as shown in Figure 1. When the seat belt assembly 22 is solelv supported bv the seat 10, the seat 10 will be subject to a higher seat load than

if the seat belt assembly 11 were supported by a vehicle structure. When a seat occupant experiences a deceleration, the seat 10 experiences a seat load, which is transferred to the inboard and outboard track assemblies 20. This is known as an"all belts to seat"load. One of the avantages of the subject seat track assembly 20, is that it is a simplifie and light weight seat track assembly 20 that can support an all belts to seat load.

While the track assembly 20 is preferably used on a seat 10 that has the seat belt assembly 22 solely supported by the seat 10, the track assembly 20 can be used on other types of seat belt arrangements well known in the art. For example, the track assembly 20 could be used on a seat having part of the seat belt supported by the seat and part of the seat belt supported by a vehicle structure such as a vehicle floor or vehicle pillar. These types of seat belt arrangements are known as a"travel inboard buckle"or"lap belt to seat"applications.

The mounting assembly 18 is shown in greater detail in Figure 2. Both the inboard and outboard track assemblies 20 include a first track 24 and a second track 26. The first track 24 in this particular embodiment is preferably a lower or outer track 24 that is fixedly mounted to the vehicle structure 16 such as a vehicle floor, for example. The second track 26 is preferably an upper or inner track 26 and is received within the outer track 24 so that the inner track 26 can be moved in a forward or rearward direction relative to the outer track 24. The terms forward, rearward, upper, lower, inner, and outer as used in this description, are for illustration purposes only and cannot be considered limiting. The profiles of the outer track 24 and the inner track 26 ensure that the inner track 26 only moves along a longitudinal axis 70 (shown in Figure 3) of the tracks 24.26 and does not move in other directions.

The inboard and outboard track assemblies 20 preferably have the same cross sectional shape as shown in Figures 2-5, thus the following description will be directed towards the outboard track assembly 20 with the understanding that a similar description also applies to the inboard track assembly 20.

As shown in Figure 4, the outer track 24 has a first pair of sidewalls 28 interconnected by an outer base portion 30. The inner track 26 has a second pair of

sidewalls 32 spaced apart from the first pair of sidewalls 28 and interconnected by an inner base portion 34.

The first pair of sidewalls 28 each have an outwardly extending groove 36. Each of the outwardly extending grooves 36 presents opposing outer bearing surfaces 38.

The second pair of sidewalls 32 each have an inwardly extending groove 40 wherein the inwardly extending grooves 40 are mounted opposite from the outwardly extending grooves 36 to form a pair of bearing channels 42 between the first 28 and second 32 pairs of sidewalls. Each of the inwardly extending grooves 40 presents opposing inner bearing surfaces 44 that face the outer bearing surfaces 38 to form the bearing channels 42 between the first 28 and second 32 pairs of sidewalls. Thus, the inwardly extending grooves 40 form the inner bearing surface 44 of the bearing channel 42 and the outwardly extending grooves 36 form an outer bearing surface 38 of the bearing channel 42.

A bearing member 46 is inserted in each of the bearing channels 42 and includes a bearing surface 48 for engaging the outer 38 and inner 44 bearing surfaces.

The bearing member 46 supports the second track 26 with respect to the first track 24 and creates a rolling effect between the tracks 24,26 and the bearing member 46 to improved seat adjustment capability.

Each of the bearing members 46 is preferably comprised of a plurality of ball bearings having a circular cross sectional area. The bearing channels 42 have a non- circular cross sectional area that is larger than the circular cross sectional area of the bearings. This configuration allows the seat track assembly 20 to have point contact between the bearing members 46 and the tracks 24,26, as will be discussed in greater detailbelow.

The inwardly extending grooves 40 are aligned with the outwardly extending grooves 36 to define a central axis 48 disposed transversely to the longitudinal axis 70.

Each of the outwardly extending grooves 36 includes an outer base portion 50 defining an outer base point 52 and each of the inwardly extending grooves 40 includes an inner base portion 54 defining an inner base point 56. Preferably, the inner 52 and outer 56 base points are collinear to define the central axis 48.

In the preferred embodiment, the tracks 24. 26 are vertically mounted such that the outer base portion 30 and the inner base portion 34 are transverse to the central axis 48. However, it should be understood that the tracks 24. 26 could be transposed and could also be mounted horizontally, such that the outer base portion 30 and inner base portion 34 are parallel to the central axis 48.

As shown in Figure 5B. the inner bearing surface 44 is preferably comprised of two inner surfaces 44a, 44b originating at an apex 66 on the central axis 48 and extending radially outwardly from opposite sides of the central axis 48 forming a V.

As shown in Figure SA, the outer bearing surface 38 is preferably comprised of two outer surfaces 38a, 38b, at an apex 68 on the central axis 48 and extending radially outwardly from opposite sides of the central axis 48 forming a V.

The bearing member 46 has four (4) contact points in each of the bearing channels 42. The four contact points include: a first contact point 58 between one of the inner surfaces 44a and the bearing member 46 ; a second contact point 60 between the other of the inner surfaces 44b and the bearing member 46; a third contact point 62 between one of the outer surfaces 38a and the bearing member 46; and a fourth contact point 64 between the other of the outer surfaces 38b and the bearing member 46. This four contact point configuration creates a rolling effect between the bearing members 46 and the tracks 24,26 that improves seat adjustment performance and stability.

The subject invention offers several avantages over prior art seat track assemblies because it provides a light weight, durable, and robust mounting assembly that reduces the overall number of parts, reduces weight and overall assembly cost, and which can accommodate an all belts to seat load. The subject invention also provides a stable seat track assembly that has point contact between a bearing member and the seat track members to create a rolling effect between the seat track members and the bearing members. The seat track assembly also maintains a clearance between the first and second track members under load to avoid seat track scraping.

Preferred embodiments of this invention have been disclosed, however, a worker of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.