GB2436017A

GB2436017A - Hydroformed back frame for automobile seat

Info

Publication number: GB2436017A
Application number: GB0704438A
Authority: GB
Inventors: Vincent Adragna; Eric Beaulieu; Gary Greiner
Original assignee: Lear Corp
Current assignee: Lear Corp
Priority date: 2006-03-08
Filing date: 2007-03-08
Publication date: 2007-09-12
Anticipated expiration: 2027-03-08
Also published as: US20070210638A1; GB2436017B; GB0704438D0; DE102007001144A1

Abstract

An automobile seat frame assembly 1 comprises a back frame 15 formed from a hydroformed hollow metal tube having a cross-section which varies in shape along its length. The tube has a first vertical support section 16 having a top end 19 and a bottom end 20, a second vertical support section 17 having a top end 23 and a bottom end 22, and a transverse section 18 extending between the respective top ends of the first and second support sections. The bottom ends of the vertical support sections may have a cross-sectional shape which corresponds to that of attachment protrusions (40, Fig. 4a) provided on a bottom frame (10, Fig. 1), to facilitate attachment of the back frame to the bottom frame. The transverse section may include punched or extruded holes 35 to receive a headrest. Also disclosed are a method of making such a frame assembly, and a seat comprising such a frame assembly.

Description

HYDROFORMED SEATBACK FRAME

The present invention relates to an automotive seat frame assembly, and in particular to a hydroformed seatback frame.

A hydroformed seatback frame is disclosed herein. Examples of electrical hydroformed seat components are disclosed in US Patent Numbers 6,352,311; 6,957,796; 5,564,785; 5,437,498; 5,452,941; 5,845,382; and 5,988,756 as well as published Application No. 2004/0135411.

It is desirable to provide an improved automotive seat frame assembly which offers improvements over the above arrangements, and which offers improvements generally.

According to the present invention there is provided an automotive seat frame assembly as described in the accompanying claims. In addition, according to the present invention there is provided an automotive seatback frame, and an automotive seat assembly as described in the accompanying claims. According to the present invention there is also provided a method of making an automotive seat frame as described in the accompanying claims.

In accordance with an embodiment of one aspect of the present invention, an automotive seat frame assemb]y is provided comprising an automotive seatbottom frame connected to an automotive seatback frame. The automotive seatback frame includes a hydroformed hollow metal tube having a cross-section which varies in shape along its length. In this embodiment, the hydroformed hollow metal tube has a first vertical support section having a top end and a bottom end, a second vertical support section having a top end and a bottom end, and a traverse section extending between the respective top ends of the first and second support sections.

In accordance with an embodiment of another aspect of the present invention, an automotive seatback frame is provided for use with an automotive seat having a seatbottom and seatbottorn frame, a seatback and seatback frame. The automotive seatback frame includes a hydroformed hollow metal tube having a cross-section which varies in shape along its length. In this embodiment, the hydroformed hollow metal tube has a first vertical support section having a top end and a bottom end, a second vertical support section having a top end and a bottom end, and a traverse section extending between the respective top ends of the first and second support sections.

In accordance with an embodiment of yet another aspect of the present invention, an automotive seat assembly is provided, which includes an automotive seatbottom and an automotive seat back. The automotive seatbottom includes an automotive seatbottom frame, an automotive seatbottom cushion supported on the automotive seatbottom frame and an automotive seatbottom cover covering the automotive seatbottom frame and automotive seatbottom cushion. The automotive seatback includes an automotive seatback frame, an automotive seatback cushion supported on the automotive seatback frame and an automotive seatback cover covering the automotive seatback frame and the automotive seatback cushion. The automotive seatback frame is connected to the automotive seatbottorn frame. Furthermore, the automotive seatback frame includes a hydroformed hollow metal tube having a cross-section which varies in shape along its length. In this embodiment, the hydroformed hollow metal tube has a first vertical support section having a top end and a bottom end, a second vertical support section having a top end arid a bottom end, and a traverse section extending between the respective top ends of the first and second support sections.

While exemplary embodiments in accordance with the invention are illustrated and disclosed, such disclosures should not be construed to limit the claims.

It is anticipated that various modifications and alternative designs may be made without departing from the scope of the invention.

The present invention will now be described by way of example only, and with reference to the following illustrative figures in which: FIGURE 1 is a cut away perspective view of an automotive seat assembly showing an automotive seat frame assembly made in accordance with an embodiment of the present invention; FIGURE 2 is a perspective view of a component of the automotive seat frame assembly illustrated in Figure 1; FIGURE 3 is a cross-sectional view of the component illustrated in Figure 2 taken along the line 3-3 of Figure 2; FIGURE 4a is a perspective view of the component illustrated in Figure 2 prior to its connection with another component of the automotive seat frame assembly illustrated in Figure 1; FIGURE 4b is a perspective view of the component illustrated in Figure 2 connected to the component of the automotive seat frame assembly illustrated in Figure 4a; FIGURE 5 is a cross-sectional view of the component illustrated in Figure 2 taken along the line 5-5 of Figure 2; FIGURE 6 is a cross-sectional view of the component illustrated in Figure 2 taken along the line 6-6 of Figure 2; and FIGURE 7 is a cross-sectional view of the component illustrated in Figure 2 taken along the line 7-7 of Figure 2.

The following descriptions are merely exemplary

in nature and are in no way intended to limit the invention, its application, or its uses.

Reference will now be made in detail to presently preferred compositions, embodiments and methods of the present invention, which constitute the best modes of practicing the invention presently known to the inventors. The Figures are not necessarily to scale.

However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of the invention and/or as a representative basis for teaching one skilled in the art to variously employ the present invention.

Referring to figure 1, a cut-away perspective view of an exemplary automotive seat assembly 1 is illustrated. The automotive seat assembly 1 illustrated in figure 1 includes an automotive frame assembly 5, a seatbottom cushion 2, a seatbottorn cover 3, a seatback cushion 4, and a seatback cover 6. The automotive seat frame assembly 5 includes an automotive seatbottom frame 10. The automotive seatbottom frame 10 is mountable, as shown in figure 1, on a set of tracks 11 usable to mount the automotive seat frame assembly 5 to an automobile (not shown) . The automotive seat frame assembly 5 further includes a hydroformed automotive seatback frame 15 connected to the automotive seatbottom frame 10.

The hydroformed automotive seatback frame 15 shown in Figure 2, is made using a suitable hydroforming process. 1-lydroforming is a relatively well known manufacturing process and generally includes placing a hollow metal blank in a mold cavity, closing the mold which, in turn, causes the hollow metal blank to partially conform to the shape of the mold cavity. The hollow portion of the blank is then filled with fluid at a high enough pressure to cause the walls of the metal blank to expand until they are flush with the surface of the mold cavity. The fluid is then drained from the blank, the mold is opened, and the hollow metal blank, now a hydroformed metal part, is removed.

The hydroformed automotive seatback frame 15 has a cross-section that varies along its length. This varying cross section can facilitate attachment of items to the hydroformed automotive seatback frame 15 as well as attachment of the hydroformed automotive seatback frame 15 to the automotive seat bottom frame 10. The cross sectional variations can also provide structural reinforcement at desired locations along the automotive seatback frame. Moreover, the seatback frame 15 is relatively resistant to bending and twisting compared with conventional seatback frames that either have varying cross sections but which are not hollow, or which are hollow but do not have varying cross sections.

While the seatback frame 15 may be made of any suitable metal, in at least one embodiment, the hydroformed seatback frame 15 is made of SAE O5OXF steel. In at least one embodiment, the seatback frame 15 has a rear load strength to weight ratio of at least 3.0 KN/Kg, in at least another embodiment of at least 3.16 KN/Kg, and in at least yet another embodiment of at least 3.25 KN/Kg. In at least one embodiment, the seatback frame has a rear load strength to weight ratio of approximately 15% greater than the rear load strength to weight ratio of a standard stamped steel construction rear seat back made of the same material, in another embodiment of approximately 20% greater, and in yet another embodiment approximately 25% greater.

In at least one embodiment, the hydroforming mold can be configured to punch and/or extrude holes in the hydroformed automotive seatback frame 15 during molding.

This can permit the relatively easy insertion of appendages, such as a headrest into the hydroformed automotive seatback frame 15 and/or the fastening of the hydroformed automotive seatback frame 15 to the automotive seat bottom frame 10. This can be done using a mold designed with punches in desirable locations. During the hydroforming process, after the hollow metal blank has been formed, arid before the pressure of the fluid is reduced, the punch, in cooperation with the fluid, is able to punch or extrude holes as desired in the surface of the hollow metal tube. This can save time and reduces cost by permitting a one-step manufacturing process.

The hydroformed automotive seatback frame 15 illustrated in Figure 2 has a first vertical support section 16, a second vertical support section 17 and a transverse section 18. The first vertical support section 16 has a bottom end 20 and a top end 19. The second vertical support section 17 has a bottom end 22 and a top end 23. The transverse section 18 extends between and connects the top end of the first vertical support section 19 and the top end of the second vertical support section 23.

As illustrated in Figure 2, this embodiment of the hydroformed automotive seatback frame 15 has four areas of distinct cross-sectional geometry. It should be understood that a greater or lesser number of distinct cross-sectional geometries may be used, depending on design requirements.

A first distinct cross-sectional geometry of the embodiment illustrated in Figure 2 is at the bottom ends of the first and second vertical support sections 20, 22. In this embodiment, bottom ends 20, 22 have been shaped to facilitate the attachment of the hydroformed automotive seatback frame 15 to the automotive seatbottom frame 10.

An example of a bottom end cross-section is shown in Figure 3, where the cross section of bottom end 22 has at least partially been formed into a relatively thin channel capable of receiving posts or other protrusions 40 (see figure 4a) from the seatbottom frame 10. The cross-section depicted in Figure 3 was taken along the line 3-3 from Figure 2.

Attachment of the exemplary hydroformed automotive seatback frame 15, illustrated in figure 2, to the automotive seatbottom frame 10 is depicted in Figures 4a and 4b. As illustrated in Figure 4a, attachment protrusions 40 are received within the respective bottom ends of the first and second vertical support sections 20, 22. Figure 4b illustrates the exemplary hydroformed automotive seatback frame 15 fully seated on the attachment protrusions 40. In the embodiment depicted in Figure 4b, holes have been punched through the walls of the bottom ends 20 and 22 to facilitate fastening the hydroformed automotive seatback frame to the automotive seatbottom.

The geometry of the attachment protrusions 40 could easily be altered to allow the attachment protrusions 40 to receive the bottom ends of the vertical support sections 20, 22.

A second distinct cross-sectional geometry of the exemplary hydroformed automotive seatback frame 15 illustrated in Figure 2 is located approximately halfway up the first and second vertical support sections. Figure 5 depicts a cross-sectional view of the exemplary automotive hydroformed seatback frame 15 taken along the lines 5-5, depicted in Figure 2. As shown in Figure 5, the cross-sectional geometry is gener1ly tringuiar. In this embodiment, the triangular cross-section is located where the first and second vertical support sections 16,17 will experience the highest load during a rear impact. A triangular cross-sectional geometry provides good -9--resistance to impact force, such as those the seatback frame is likely to experience in the event of a rear-end collision.

A third distinct cross-sectional geometry of the embodiment shown in Figure 2 is located along the transverse section 18. Figure 6 shows a cross-sectional view taken horizontally along the line 6-6 (shown in Figure 2) through the transverse section 18. As illustrated, transverse section 18 has a front side 41 and a back side 42. A depression 30 has been formed in the front side 41.

This depression will provide added support for the neck of an occupant of the automotive seat assembly 1 during a rear-end collision. The depression may also provide additional comfort to the occupant during normal vehicle operations.

A fourth distinct cross-sectional geometry of the embodiment shown in Figure 2, also located along the transverse section 18, is illustrated in Figure 7. Figure 7 illustrates a cross-sectional view of the exemplary hydroformed automotive seatback frame 15 taken vertically along the line 7-7 (shown in Figure 2) through the transverse section 18. This cross section is generally rectangular. This shape provides excellent resistance to rotation which makes it well suited to support a headrest.

In the embodiment of the bydroformed automotive seatback frame 15 depicted in Figure 2, holes have been extruded in the transverse section 18. This is illustrated in Figure 7 which illustrates a vertical cross-sectional cut through the transverse section 18 along the lines 7-7 (shown in Figure 2) . Line 7-7 of Figure 2 intersects the transverse section 18 through one of two adaptations to receive a headrest 35. Transverse section 18 has a top side 37 and a bottom side 38. The adaptation to receive a headrest 35 consists of a hole extruded into the top side 37 of the transverse section 18 that is coaxial with a second hole extruded into the bottom side 38 of the transverse section 18. The extruded portion of the holes is indicated by the reference numeral 45 in Figure 7.

It is desirable that the thickness of its walls remain relatively constant. Traditional high pressure hydroforming methods can result in attenuated wall thicknesses at curved areas of the hydroformed product.

One way to ensure consistent wall thickness is to use a pressure sequence hydroforming process. According to this process, the hollow metal blank is placed in the mold cavity and the mold is partially closed causing some deformation of the blank. The hollow portion of the blank is then filled with fluid that is maintained within the hollow portion of the blank at a low pressure. The cavity is then closed completely. As the die closes completely, the walls of the blank are supported internally by the fluid. Once the die is completely closed, the internal fluid pressure is increased to finish forming the product and also to provide backup for punching holes. This method of low pressure hydroforming is fully disclosed in U.S. Patent No. 6,397,449 to Mason et al., the disclosure of which is herein incorporated by reference. Use of the pressure sequence hydroforming process minimizes attenuation of wall thickness around c'.urves and corners.

The embodiment of the hydroformed automotive seatback frame 15 shown in Figure 2 was made using a pressure sequence hydroforming process. Accordingly, the wall thickness of flat and curved portions are substantially the same. This is depicted in Figures 3, 5, 6, and 7. The wall thickness 21 of bottom end 20 is consistent throughout the entire cross-section, as shown in Figure 3. The same is true of wall 26 of the triangular cross-section of the second vertical support section 17 (as shown in Figure 5), the wall thickness 31 of the transverse section 18 (as shown in Figure 6), and wall thickness 36 of the transverse section 18 (as shown in Figure 7) In another aspect of the invention, a method of making an automotive seat frame is disclosed. According to this aspect of the invention, an automotive seatbottom frame 10 is provided, a hydroformed automotive seatback frame 15 including a hydroformed hollow metal tube having a cross-section which varies in shape along its length, the tube having a first vertical support section having a top end and a bottom end, a second vertical support section having a top end and a bottom end, and a transverse section extending between the top ends of the first and second support sections is provided, and the automotive seatbottom frame is connected to the automotive seatback frame.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the scope of the invention.

Claims

CLAIMS

1. An automotive seat frame assembly comprising: an automotive seatbottom frame; and an automotive seatback frame connected to the seatbottom frame, the seatback frame comprising a hydroformed hollow metal tube having a cross-section which varies in shape along its length, the hydroformed hollow metal tube having a first vertical support section having a top end and a bottom end, a second vertical support section having a top end and a bottom end, and a transverse section extending between the respective top ends of the first and second support sections.

2. The automotive seat frame assembly of claim 1, wherein the hydroformed hollow metal tube comprises a wall having substantially uniform thickness along its entire length.

3. The automotive seat frame assembly of claim 1 or 2, wherein the cross-sectional shape of the hydroformed hollow metal tube is formed using a low pressure hydroforming process.

4. The automotive seat frame assembly of any preceding claim, wherein the bottom ends of the vertical support sections have a cross-sectional shape that facilitates connection of the seatback frame to the seatbottom frame.

5. The automotive seat frame assembly of any preceding claim, wherein the cross-sections of the respective bottom ends of the first and second vertical support sections have a shape that corresponds with the shape of the seatbottom frame at the location where the seatback frame is connected to the seatbottom frame.

6. The automotive seat frame assembly of any preceding claim, wherein the cross-sections of the respective bottom ends of the first and second vertical support sections are shaped to be received by, or be received within, the seatbottom frame connecting the seatback frame to the seatbottom frame.

7. The automotive seat frame assembly of any preceding claim, wherein a portion of at least one of the vertical support sections has a generally triangular cross-section.

8. The automotive seat frame assembly of claim 7, wherein the triangular cross-section is at a location of the at least one vertical support section where the at least one of the vertical support sections will bear the highest load during a rear impact.

9. The automotive seat frame assembly of any preceding claim, wherein the transverse section has a front side and wherein at least a portion of the front side is depressed to form a recess large enough to receive a person's neck.

10. The automotive seat frame assembly of any preceding claim, wherein the transverse section is adapted to receive a headrest.

11. The automotive seat frame assembly of claim 10 wherein the transverse section has a top side and a bottom side, wherein the top side has a pair of holes and the bottom side has a pair of holes, and wherein the pair of holes in the top side are axially aligned with the pair holes in the bottom side to enable the transverse section to receive posts from a headrest.

12. The automotive seat frame assembly of claim 11 wherein the holes are extruded.

13. An automotive seatback frame for use with an automotive seat having a seatbottom having a seatbottom frame, and a seatback having a seatback frame, the automotive seatback frame comprising: a hydroformed hollow metal tube having a cross-section which varies in shape along its length, the tube having a first vertical support section having a top end and a bottom end, a second vertical support section having a top end and a bottom end, and a transverse section extending between the top ends of the first and second support sections.

14. The automotive seatback frame of claim 13 wherein the automotive seatback frame is made from SAE O5OXF steel and wherein the automotive seatback frame has a rear load strength to weight ratio of at least approximately 3.0 KN/Kg.

15. A method of making an automotive seat frame comprising the steps of: providing an automotive seatbottorn frame; providing the automotive seatback frame of claim 13 or 14; and connecting the automotive seatbottom frame to the seatback frame.

16. An automotive seat assembly comprising: an automotive seatbottom comprising an automotive seatbottorn frame, an automotive seatbottom cushion supported on the automotive seatbottom frame and an automotive seatbottom cover covering the automotive seatbottom frame and automotive seatbottom cushion; an automotive seatback comprising an automotive seatback frame, an automotive seatback cushion supported on the automotive seatback frame and an automotive seatback cover covering the automotive seatback frame and the automotive seatback cushion, the automotive seatback frame being connected to the automotive seatbottom frame; the automotive seatback frame comprising a hydroformed hollow metal tube having a cross-section which varies in shape along its length, the hydroformed hollow metal tube having a first vertical support section having a top end and a bottom end, a second vertical support section having a top end and a bottom end, and a transverse section extending between the respective top ends of the first and second support sections.

17. The automotive seat assembly of claim 16 wherein the hydroformed hollow metal tube comprises a wall having substantially uniform thickness along its entire length.

18. The automotive seat assembly of claim 16 or 17, wherein the bottom ends of the vertical support sections have a cross-sectional shape that facilitates the connection of the seatback frame to the seathottorn frame.

19. The automotive seat assembly of any one of claims 16 to 18, wherein a portion of at least one of the vertical support sections has a generally triangular cross-section, wherein the transverse section has a front side wherein at least a portion of the front side is depressed to form a recess large enough to receive a person's neck and wherein the transverse section is adapted to receive a headrest.

20. An automotive seat frame assembly substantially as hereinbefore described with reference to, and/or as shown in any one or more of figures 1 to 7.

21. An automotive seatback frame substantially as hereinbefore described with reference to, and/or as shown in any one or more of figures 1 to 7.

22. A method of making an automotive seat frame substantially as hereinbefore described with reference to, and/or as shown in any one or more of figures 1 to 7.

23. An automotive seat assembly substantially as hereinbefore described with reference to, and/or as shown in any one or more of figures 1 to 7.