WO2008046198A1

WO2008046198A1 - Head restraint sleeve

Info

Publication number: WO2008046198A1
Application number: PCT/CA2007/001805
Authority: WO
Inventors: Nathan A. Jensen
Original assignee: Intier Automotive Inc.
Priority date: 2006-10-13
Filing date: 2007-10-15
Publication date: 2008-04-24

Abstract

A plastic head restraint sleeve is provided for coupling and guiding an elongated armature of a head restraint to a seat back. The sleeve is inserted into a guide tube mounted to the seat back. The sleeve includes a cylindrical body having upper and lower ends, an outer surface, a generally circular bore extending between the upper and lower ends, and at least one vertical slot extending between the upper and lower ends. A plurality of ribs integral with the outer surface of the cylindrical body that protrude radially outward to contact an inner surface of the guide tube. At least one beam extends circumferentially across each of the vertical slots. The beams define an inner profile of the sleeve which contacts the armature to frictionally guide the armature through the sleeve and minimize vertical adjustment efforts of the head restraint.

Description

HEAD RESTRAINT SLEEVE CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to and all the benefits of United States

Provisional Application serial number 60/851,673, filed on October 13, 2006 and entitled "Low Friction Load Bearing Plastic Bushing for Head Restraint."

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] The invention relates to a head restraint for an automotive vehicle seat, and more particularly, to a head restraint sleeve bushing for slidably guiding head restraint armatures during vertical adjustment of the head restraint relative to the seat.

Description of Related Art

[0003] Head restraint structures mounted on vehicle seat backs to provide occupant comfort and safety are well known in the art. Typically, at least one armature extends vertically from the head restraint to attach the head restraint to the seat back. The seat back includes a frame, with a guide tube stamped frame extending through a portion of the frame for receiving the armature. A sleeve bushing is often inserted in the guide tube to allow vertical adjustment of the head restraint according to occupant preference.

[0004] Prior art sleeve bushings are usually fabricated from plastic and inserted into the guide tube for receiving and engaging the armature. Thus, guide tube size variation has a significant effect on head restraint adjustment efforts. Typically, the guide tube, sleeve bushing, and armature all interact resulting in either a low friction condition between the armature and sleeve bushing, or a high friction condition.

[0005] The low friction condition is unsatisfactory in that it is characterized by excessive noise caused by the buzz, squeak and rattle of the armature within the sleeve bushing due to insufficient or uneven frictional engagement between the sleeve bushing and the armature. This problem has become more significant in recent years as automotive vehicles have been aerodynamically and acoustically designed to reduce noise within the passenger compartment, thereby calling attention to the noise caused by the head restraint. A second problem with the low friction condition is it allows for front- to-back chuck of the head restraint, which not only generates noise, but causes a corresponding chuck to the head of the occupant. A third problem is that the aforementioned insufficient and uneven frictional engagement between the sleeve bushing and the armature prevents smooth movement of the armature within the sleeve bushing, making the vertical adjustment of the head restraint awkward for the occupant.

[0006] The high friction condition is unsatisfactory in that it is characterized by a high resistance force between the sleeve bushing and the armature, making the vertical adjustment of the head restraint increase to a level above the occupant's acceptable limit.

[0007] It is therefore a goal of the invention to provide an improved head restraint sleeve bushing affording a toleranced fit between the armature and the sleeve bushing which prevents unwanted vibrations by sufficiently restraining the armature within the sleeve bushing while still allowing easy vertical adjustment of the head restraint. It is another goal of the invention to provide a sleeve bushing which separates forces acting on the guide tube from forces acting on the armature thereby eliminating guide tube size variation from having a significant effect on vertical adjustment efforts.

SUMMARY OF THE INVENTION

[0008] According to one aspect of the invention, a plastic head restraint sleeve is provided for coupling and guiding an elongated armature of a head restraint to a seat back. The sleeve is inserted into a guide tube mounted to the seat back. The sleeve includes a cylindrical body having upper and lower ends, an outer surface, a generally circular bore extending between the upper and lower ends, and at least one vertical slot extending between the upper and lower ends. A plurality of ribs integral with the outer surface of the cylindrical body that protrude radially outward to contact an inner surface of the guide tube. At least one beam extends circumferentially across each of the vertical slots. The beams define an inner profile of the sleeve which contacts the armature to fiictionally guide the armature through the sleeve and minimize vertical adjustment efforts of the head restraint.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

[0010] Figure 1 is a fragmentary, front perspective view of a seat assembly including a vertically adjustable head restraint;

[0011] Figure 2 is a rear perspective view of a first embodiment of a head restraint sleeve inserted into a guide tube fixedly mounted to a seat back frame according to the invention;

[0012] Figure 3 is a cross-sectional side view taken along lines 3-3 of Figure 2;

[0013] Figure 4 is a perspective view of the first embodiment of the head restraint sleeve;

[0014] Figure 5 is a cross-sectional top view taken along lines 5-5 of Figure 3;

[0015] Figure 6 is a cross-sectional top view taken along lines 6-6 of Figure 3;

[0016] Figure 7 is a side view of the head restraint sleeve supporting the head restraint;

[0017] Figure 8 is a front perspective view of a second embodiment of a head restraint sleeve inserted into a stamped seat back frame;

[0018] Figure 9 is a cross-sectional side view taken along lines 9-9 of Figure 8;

[0019] Figure 10 is a perspective view of the second embodiment of the head restraint sleeve;

[0020] Figure 11 is a cross-sectional top view taken along lines 11-11 of Figure 9;

[0021] Figure 12 is a cross-sectional top view taken along lines 12-12 of Figure 9; and [0022] Figure 13 is a cross-sectional top view taken along lines 13-13 of Figure 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Referring to Figure 1 , a partial view of a typical seat assembly is generally shown at 10. The seat assembly 10 includes a seat back 12, a seat cushion (not shown), and a head restraint 14. The head restraint 14 is adjustably attached to the seat back 12 via a pair of spaced apart and parallel armatures 16. The armatures 16 are slidably coupled to a seat back frame 18 within the seat back 12, as shown in Figure 2, for providing vertical sliding adjustment of the head restraint 14 relative to the seat back 12. At least one of the armatures 16 includes a plurality of vertically spaced apart notches 19, one of which is shown in Figure 5, for locking the head restraint 14 in a desired position.

[0024] A pair of guide tubes 20 extends through and is fixedly mounted to the seat back frame 18 by welding or any other suitable method, as shown in Figure 2. The seat back frame 18 is preferably U-shaped, but a seat back frame of any configuration may be used without compromising the inventive concept. Referring to Figures 2 and 3, each guide tube 20 is typically circular in cross section and extends between an upper end 22 and a lower end 24. A bore 26 extending axially between the upper 22 and lower 24 ends defines an inner surface 28 of the guide tube 20. The upper end 22 of each guide tube 20 includes a pair of opposing vertical slots 30.

[0025] A plastic sleeve 32 is inserted into the bore 26 of each guide tube 20 as shown in Figure 3. Preferably the sleeve 32 is manufactured from high density polyethylene plastic which provides a minimum coefficient of friction compared with other plastic sleeve materials. Referring to Figure 4, the sleeve 32 includes a generally cylindrical body 34 extending between an upper end 36, which is topped by a cap 38, and a lower end 40 having a slightly tapered portion 42. A bore 44 extending axially through the sleeve 32 is adapted for receiving one of the armatures 16 therein to couple the head restraint 14 to the seat assembly 10. The cap 38 is provided to cover an access hole (not shown) in the seat back trim cover. It will be appreciated that the cap 38 can be either of a non-locking type, as shown at A in Figure 2, or a locking type, as shown at B in Figure 2, having a locking mechanism 45 for selectively engaging one of the notches 19 disposed along the armature 16 to selectively prevent vertical movement of the head restraint 14 once the desired head restraint position is selected.

[0026] Referring to Figures 2 through 4, the upper end 36 of the cylindrical body

34 includes a pair of opposing keys 46 extending radially outward for engagement with the vertical slots 30 in the upper end 22 of the guide tube 20 to prevent rotation of the sleeve 32 within the guide tube 20. The lower end 40 of the cylindrical body 34 includes at least one retention tab 48 which engages the lower end 24 of the guide tube 20. To allow for the bending necessary to get the retention tab 48 inside the bore 26 of the guide tube 20, the retention tab 48 is flexibly mounted to the cylindrical body 34 to allow inward bending. After the sleeve 32 is fully inserted within the guide tube 20, the retention tab 48 will resiliently push to restore itself to a free state, bringing the retention tab 48 into a semi-permanent locking arrangement with the lower end 24 of the guide tube 20. Henceforth, removal of the sleeve 32 from the guide tube 20 will not occur unless the retention tab 48 is deliberately pushed inwardly.

[0027] It is contemplated that the sleeve 32 may include fewer than or more than three vertical slots and correspondingly fewer than or more than three horizontal beams for defining the inner profile for establishing contact with the armature 16 without varying from the scope of the invention. Additionally, the sleeve 32 may include fewer than or more than two sets of beams without varying from the scope of the invention.

[0028] Referring to Figures 4 through 6, the sleeve 32 is provided with first 50, second 52, and third 54 angularly spaced apart vertical slots extending between the upper 36 and lower 40 ends of the cylindrical body 34. The slots 50, 52, 54 are angularly spaced apart by first 56, second 58, and third 60 vertical members extending circumferentially therebetween. Additionally, the sleeve 32 includes integral first 62, second 64, and third 66 horizontal beams defining an inner profile of the cylindrical body 34 which establishes three-point contact with the armature 16, through a range of defined sizes, hi the embodiment shown, three-point contact is established at two locations along the cylindrical body 34. A first set of the beams 62, 64, 66 is located near the upper end lower end 40. The three-point contact minimizes adjustment efforts and allows only one degree of freedom for head restraint adjustment, hi particular, referring to Figure 7, the three-point contact between the beams 62, 64, 66 and the armature 16 results in normal forces acting on the armature 16 in the direction of arrows F. The normal forces F prevent excessive head restraint adjustment efforts in the direction of arrows S. Additionally, the normal forces F prevent excessive head restraint rotation in the direction of arrow R, which therefore reduces buzz, squeak and rattle.

[0029] When the head restraint 14 with the armature 16 is installed into the sleeve

32, the notches 19 in the armature 16 are aligned with the first vertical member 56, as shown in Figure 5. Thus, the first vertical member 56 is sized to angularly separate the first 62 and second 64 beams such that the inner profile of the first 62 and second 64 beams does not contact the notches 19 in the armature 16. Referring to Figure 6, in the embodiment shown, the first 50 and second 52 slots are angularly spaced apart approximately one hundred and forty (140) degrees by the first vertical member 56. The third 54 slot is equi-angularly spaced between the first 50 and second 52 slots. Thus, in the embodiment shown, the second 52 and third 54 slots are angularly spaced apart approximately one hundred and ten (110) degrees by the second vertical member 58, and the third 54 and first 50 slots are angularly spaced apart approximately one hundred and ten (110) degrees by the third vertical member 60.

[0030] Referring to Figures 5 and 6, each of the first 62, second 64, and third 66 beams extend generally circumferentially across one of the slots 50, 52, 54, between adjacent vertical members 56, 58, 60. More specifically, the first beam 62 extends horizontally between the first vertical member 56 and the third vertical member 60. The second beam 64 extends horizontally between the first vertical member 56 and the second vertical member 58, and the third beam 66 extends horizontally between the second vertical member 58 and the third vertical member 60. The spaced apart sets of beams 62, 64, 66 define a middle portion 68 of the cylindrical body 34, as shown in Figure 4.

[0031] Referring to the cross-section shown in Figure 6, each vertical member 56,

58, 60 extends between an inner surface 70 and an outer surface 72. The inner surface 70 of the vertical members 56, 58, 60 does not contact the armature 16. The outer surface 72 of the vertical members 56, 58, 60 includes a plurality of vertically extending ribs 74 disposed about the upper end 36, the middle portion 68, and the lower end 40 of the cylindrical body 34, respectively. The ribs 74 protrude radially outward from the outer surface 72 and are in contact with the inner surface 28 of the guide tube 20 for providing an interference fit between the sleeve 32 and guide tube 20.

[0032] Referring to the cross-section shown in Figure 5, each beam 62, 64, 66 extends between an arcuate outer edge 80 circumferentially aligned with the outer surface 72 of the adjacent vertical members 56, 58, 60 and a straight inner edge 82 partially dissecting the bore 44 extending through the sleeve 32. Therefore, a portion of the inner edge 82 of each beam 62, 64, 66 contacts the armature 16 extending through the bore 44. Preferably, each point of contact is 2 millimeters by 2.6 millimeters, however, it will be appreciated that the area of contact may vary depending on the desired head restraint adjustment effort without varying from the scope of the invention. When the armature 16 is subjected to abuse loads, the beams 62, 64, 66 deflect slightly until the arcuate outer edge 80 abuts the inner surface 28 of the guide tube 20 to act as an over-travel stop and prevent the beams 62, 64, 66 from bending into deformation, thus limiting deflection of the head restraint 14.

[0033] Referring to Figures 8 through 13, wherein like primed reference numerals represent similar elements as those described above, in a second embodiment of the invention the plastic sleeve bushing 32' is designed to be inserted into either a stamped or cast seat back frame 18'. The stamped or cast seat back frame 18' includes spaced apart upper 84 and lower 86 stamped or cast guide holes, each of which define an inner surface 28', as shown in Figures 8 and 9. The upper guide hole 84 is generally egg-shaped in cross-section, as shown in Figure 11, and the lower guide hole 86 is generally circular in cross-section, as shown in Figure 13.

[0034] Referring to Figure 10, the sleeve 32' includes a generally cylindrical body 34' extending between an upper end 36', which is topped by a cap 38', and a lower end 40' having a slightly tapered portion 42'. The upper end 36' of the cylindrical body 34' includes a neck portion 88 which extends through the seat back foam pad (not shown) between the cap 38' and a generally egg-shaped disc 90 that is vertically spaced apart from the cap 38'. The disc 90 extends radially outward from the cylindrical body 34' for abutting a portion of the seat back frame 18' surrounding the upper guide hole 84. A bore 44' extending axially through the sleeve 32' is adapted for receiving one of the armatures 16' therein to attach the head restraint 14' to the seat assembly 10'.

[0035] Referring to Figures 10 through 13, the sleeve 32' is provided with first

50', second 52', and third 54' angularly spaced apart vertical slots extending between the disc 90 and the lower end 40' of the cylindrical body 34'. The slots 50', 52', 54' are angularly spaced apart by first 56', second 58', and third 60' vertical members extending circumferentially therebetween. Additionally, the sleeve 32' includes integral first 62', second 64', and third 66' horizontal beams defining an inner profile of the cylindrical body 34' which establishes three-point contact with the armature 16', through a range of defined sizes. In the embodiment shown, three-point contact is established at two locations along the cylindrical body 34'. A first set of the beams 62', 64', 66' is located just below the disc 90 and a second set of the beams 62', 64', 66' is located near the lower end 40' of the cylindrical body 34'. The three-point contact minimizes adjustment efforts and allows only one degree of freedom for head restraint adjustment as described above with respect to the first embodiment.

[0036] When the head restraint 14' with the armature 16' is installed into the sleeve 32', the notches 19' in the armature 16' are aligned with the first vertical member 56'. Thus, the first vertical member 56' is sized to angularly separate the first 62' and second 64' beams such that the inner profile of the first 62' and second 64' beams does not contact the notches 19' in the armature 16'. Referring to Figure 12, in the embodiment shown, the first 50' and second 52' slots are angularly spaced apart approximately one hundred and forty (140) degrees by the first vertical member 56'. The third 54' slot is equi-angularly spaced between the first 50' and second 52' slots. Thus, in the embodiment shown, the second 52' and third 54' slots are angularly spaced apart approximately one hundred and ten (110) degrees by the second vertical member 58', and the third 54' and first 50' slots are angularly spaced apart approximately one hundred and ten (110) degrees by the third vertical member 60'.

[0037] Referring to Figures 11 through 13, each of the first 62', second 64', and third 66' beams extend generally circumferentially across one of the slots 50', 52', 54' between adjacent vertical members 56', 58', 60'. More specifically, the first beam 62' extends horizontally between the first vertical member 56' and the third vertical member 60'. The second beam 64' extends horizontally between the first vertical member 56' and the second vertical member 58', and the third beam 66' extends horizontally between the second vertical member 58' and the third vertical member 60'.

[0038] Referring to the cross-section shown in Figure 12, an inner surface 70' of each vertical member 56', 58', 60' does not contact the armature 16'. A pair of radially outwardly extending arms 92, 94 protrude from each vertical member 56', 58', 60' and provide an interference fit between the sleeve 32' and the seat back frame 18' at the upper 84 and lower 86 guide holes, as shown in Figures 11 and 13. More specifically, referring to the cross-section taken through the upper end 36' of the cylindrical body 34' just below the disc 90, as shown in Figure 11, the arms 92, 94 extending from the first vertical member 56' are generally parallel and have ends with ribs 96 which are in contact with the inner surface 28' of the upper guide hole 84. The arms 92, 94 extending from the second vertical member 58' are generally perpendicular and have ends with ribs 96 which are in contact with the inner surface 28' of the upper guide hole 84. Similarly, the arms 92, 94 extending from the third vertical member 60' are generally perpendicular having ends with ribs 96 which are in contact with the inner surface 28' of the upper guide hole 84.

[0039] Referring to the cross-section taken through the lower end 40' of the cylindrical body 34' just above the tapered portion 42', as shown in Figure 13, the arms 92, 94 extending from the first vertical member 56' are generally parallel and have ends with ribs (not shown) which are in contact with the inner surface 28' of the lower guide hole 86. The arms 92, 94 extending from the second vertical member 58' are generally perpendicular and have ends with ribs (not shown) which are in contact with the inner surface 28' of the lower guide hole 86. Similarly, the arms 92, 94 extending from the third vertical member 60' are generally perpendicular having ends with ribs (not shown) which are in contact with the inner surface 28' of the lower guide hole 86.

[0040] Referring to Figures 9 and 10, the sleeve 32' includes a pair of retention tabs 98 at the lower end 40' of the cylindrical body 34'. The retention tabs 98 engage a bottom edge 100 of the lower guide hole 86 for retaining the sleeve 32' in the seat back frame 18'.

[0041] Referring to the cross-sections shown in Figures 11 and 13, each beam

62', 64', 66' includes an arcuate inner edge 82' disposed inward of the inner surface 70' of the vertical members 56', 58', 60'. Therefore, a portion of the inner edge 82' of each beam 62', 64', 66' contacts the armature 16' extending through the bore 44' to establish the previously described three-point contact.

[0042] The invention has been described in an illustrative manner, and it is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described.

Claims

What is claimed:

1. A plastic head restraint sleeve for coupling and guiding an elongated armature of a head restraint to a seat back frame wherein the armature defines an armature circumference, said sleeve comprising:

a generally cylindrical body having an upper end and an opposite lower end, an outer surface, a generally circular bore extending between said upper and lower ends for receiving the armature therein, and at least one vertical slot extending through said outer surface of said cylindrical body and between said upper and lower ends;

a plurality of ribs integral with said outer surface of said cylindrical body, said ribs protruding radially outward to contact the seat back frame; and

at least one beam extending circumferentially across said at least one vertical slot, said at least one beam defining an inner profile for contacting the armature circumference to fiϊctionally guide the armature through said sleeve and minimize adjustment efforts of the head restraint.

2. A plastic head restraint sleeve as set forth in claim 1 wherein said generally cylindrical body includes three vertical slots extending through said outer surface of said cylindrical body and between said upper and lower ends, said slots defining a first slot, a second slot, and a third slot.

3. A plastic head restraint sleeve as set forth in claim 2 wherein said three vertical slots are angularly spaced apart at predefined angles.

4. A plastic head restraint sleeve as set forth in claim 3 further including a first beam extending circumferentially across said first slot, a second beam extending circumferentially across said second slot, and a third beam extending circumferentially across said third slot, said first, second, and third beams defining said inner profile for contacting the armature circumference.

5. A plastic head restraint sleeve as set forth in claim 4 wherein said first, second, and third beams define a set of beams, wherein said set of beams establishes three-point contact with the armature circumference.

6. A plastic head restraint sleeve as set forth in claim 5 wherein there are at least two sets of beams.

7. A plastic head restraint sleeve as set forth in claim 6 wherein said at least two sets of beams are vertically spaced apart.

8. A plastic head restraint sleeve as set forth in claim 7 wherein said upper end of said cylindrical body includes a cap having a periphery at least as large as said cylindrical body.

9. A plastic head restraint sleeve as set forth in claim 8 wherein said upper end of said cylindrical body includes at least one key extending radially outward for engagement with the guide tube to position said sleeve in the guide tube and prevent rotation of said sleeve.

10. A plastic head restraint sleeve as set forth in claim 9 wherein said outer surface of said cylindrical body is tapered inwardly at said lower end thereof.

11. A plastic head restraint sleeve as set forth in claim 10 wherein said lower end of said cylindrical body includes at least one retention tab flexibly mounted thereto for locking engagement with the guide post tube to retain said sleeve therein.

12. A plastic head restraint sleeve as set forth in claim 11 wherein said plurality of ribs extend vertically along said outer surface of said generally cylindrical body.

13. A plastic head restraint sleeve as set forth in claim 3 wherein said first and second slots are angularly spaced apart approximately one hundred forty degrees, said second and third slots are angularly spaced apart approximately one hundred ten degrees, and said third and first slots are angularly spaced apart approximately one hundred ten degrees.

14. A plastic head restraint sleeve as set forth in claim 12 wherein said plurality of ribs do not extend along a portion of said outer surface of said generally cylindrical body adjacent to said at least two sets of beams.

15. A plastic head restraint sleeve for coupling and guiding an elongated armature of a head restraint to a seat back frame wherein the armature defines an armature circumference, said sleeve comprising:

at least one arm extending radially outward from said outer surface of said cylindrical body, said arm having an end with at least one rib integral with said end, said at least one rib protruding radially outward to contact the seat back frame; and

at least one beam extending circumferentially across said at least one vertical slot, said at least one beam defining an inner profile for contacting the armature circumference to frictionally guide the armature through said sleeve and minimize adjustment efforts of the head restraint.

16. A plastic head restraint sleeve as set forth in claim 15 wherein said upper end of said cylindrical body includes a neck portion extending vertically between a cap and a disk spaced apart from said cap.