WO2009073971A1

WO2009073971A1 - Powered retracting head restraint

Info

Publication number: WO2009073971A1
Application number: PCT/CA2008/002152
Authority: WO
Inventors: Omar D. Tame
Original assignee: Magna Seating Inc.
Priority date: 2007-12-11
Filing date: 2008-12-08
Publication date: 2009-06-18

Abstract

A seat assembly for supporting an occupant includes a seat back and a seat cushion. The seat back extends between a lower end coupled to the seat cushion and an opposite upper end. A head restraint is slidably coupled to the upper end of the seat back for vertical movement between a use position spaced apart from the upper end of the seat back and a stowed position adjacent the upper end of the seat back. A mechanism is operatively coupled to the head restraint for automatically moving the head restraint to the use position in response to detecting the occupant on the seat assembly and to the stowed position in response to detecting the absence of the occupant on the seat assembly.

Description

POWER RETRACTING HEAD RESTRAINT

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a seat assembly for an automotive vehicle. More particularly, the invention relates to a seat assembly having a head restraint that automatically moves between a stowed position and a use position in response to detecting a seat occupant on the seat assembly.

2. Description of Related Art

[0002] Seat assemblies in many passenger vehicles, such as automobiles, includes a head restraint which provides added comfort for a passenger. In addition to the comfort feature, the head restraint also provides a safety feature. Namely, the head restraint restricts head movement of a seat occupant during a rear impact collision, which reduces the likelihood of whiplash type injuries. Typically, the head restraint is mounted to an upper end of a seat back as either an integral part of the seat back or as a separate unit mounted to the seat back. The separable head restraints usually include some type of height adjustment mechanism. One problem with having head restraints, particularly in second and third row seat assemblies, is the head restraints obstruct the view for the driver and/or passengers out the rear of the automobile. Another problem is the effect of increasing the total height of the seat back. This increased height is a problem when designing stowage systems for seats. More specifically, when the seat back is folded forwardly the head restraint may interfere with a back side of a forward seat, thereby preventing the seat back from pivoting to a stowed position and reducing the total storage space within the automobile. Additionally, the head restraint may present clearance problems when attempting to stow the seat assembly within a recess in a floor of the automobile.

[0003] To address these problems, various stowable head restraint assemblies have been developed that include mechanisms for moving a head restraint between a use position and a stowed position. These mechanisms can be quite complicated and some require the head restraint be manually returned to the use position after being moved to the stowed position. It is therefore desirable to provide a simple and robust mechanism or activation

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707213PCT assembly for automatically raising and lowering a head restraint in response to detecting a seat occupant on a seat assembly.

SUMMARY OF THE INVENTION

[0004] According to one aspect of the invention, a seat assembly for supporting an occupant in a motor vehicle includes a head restraint slidably coupled to an upper end of a seat back. The head restraint is movable vertically between a use position spaced apart from the upper end of the seat back and a stowed position adjacent the upper end of the seat back. A mechanism is operative for automatically moving the head restraint between the use position and the stowed position in response to detecting the presence and absence of the occupant on the seat assembly.

[0005] According to another aspect of the invention, a mechanism is provided for automatically moving a head restraint between a use position and a stowed position in response to detecting the presence and absence of an occupant on a seat assembly. The mechanism includes a motor for providing rotational movement in a first direction and a second direction. The mechanism also includes a drive shaft operatively coupled between the motor and a gear box for transmitting the rotational movement therebetween. The mechanism further includes a leadscrew threadably engaged with the head restraint and operatively coupled to the gear box. The motor provides rotational movement in the first direction to rotate the leadscrew in the first direction in response to detecting the presence of the occupant, thereby moving the head restraint to the use position. The motor provides rotational movement in the second direction to rotate the leadscrew in the second direction in response to detecting the absence of the occupant, thereby moving the head restraint to the stowed position.

[0006] According to still another aspect of the invention, a seat assembly for supporting an occupant in a motor vehicle includes a seat back coupled to a seat cushion. A head restraint is slidably coupled to an upper end of the seat back. The head restraint is movable vertically between a use position spaced apart from the upper end of the seat back and a stowed position adjacent the upper end of the seat back. A mechanism is operative for automatically moving the head restraint between the use position and the stowed position in response to detecting the presence and absence of the occupant. The mechanism includes a telescoping tube that extends between the head restraint and the seat back, a motor, and a

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707213PCT cable operatively coupled between the head restraint and the motor. Operation of the motor in response to detecting the presence of the occupant lengthens the cable thereby allowing the telescoping tube to extend and moving the head restraint to the use position. Operation of the motor in response to detecting the absence of the occupant shortens the cable thereby compressing the telescoping tube and moving the head restraint to the stowed position.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] 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:

[0008] Figure 1 is a perspective view of a seat assembly illustrating a head restraint in a use position and including a mechanism for moving the head restraint between the use position and a stowed position according to one embodiment of the invention;

[0009] Figure 2 is a perspective view of the seat assembly illustrating the head restraint in the stowed position;

[0010] Figure 3 is a fragmentary perspective view of the mechanism for moving the head restraint between the use and stowed positions;

[0011] Figure 4 is a fragmentary, front view of a mechanism for moving the head restraint between the use position and the stowed position according to another embodiment of the invention when the head restraint is in the use position; and

[0012] Figure 5 is a fragmentary, front view of the mechanism in Figure 4 when the head restraint is in the stowed position.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] Referring to Figures 1 through 3, a seat assembly for a motor vehicle is generally shown at 10. The seat assembly 10 includes a generally horizontal seat cushion 12 and a seat back 14 for supporting an occupant on the seat assembly 10. The seat cushion 12 has opposite and spaced apart front and rear ends 16, 18. The seat back 14 has opposite and spaced apart upper and lower ends 20, 22. The seat back 14 is pivotally coupled at its lower end 22 to the rear end 18 of the seat cushion 12 by any conventional means, such as a pair of

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707213PCT recliner mechanisms 24, as is well known in the art. The pair of recliner mechanisms 24 allows for pivotal movement of the seat back 14 relative to the seat cushion 12 about a pivot axis 28.

[0014] The construction of the seat back 14 includes a seat back frame 30 supporting a flexible foam pad encased by a trim cover, as is well known to one skilled in the art. The seat back frame 30 includes a pair of spaced apart and generally parallel side members 32, 34. Each side member 32, 34 extends between opposite upper and lower ends 36, 38. An upper cross member 40 extends between the upper ends 36 of the side members 32, 34 and a lower cross member 42 extends between the lower ends 38 of the side members 32, 34. First and second seat back brackets 44, 46 are fixedly secured to the lower ends 38 of the respective side members 32, 34 by any conventional means, such as being welded or bolted thereto. Alternatively, the first and second seat back brackets 44, 46 could be integrally formed at the lower ends 38 of the respective side members 32, 34.

[0015] Likewise, the construction of the seat cushion 12 includes a rigid seat cushion frame (not shown) for supporting a contoured foam pad encased by a trim cover. First and second seat cushion brackets 48, 50 are fixedly secured at the rear end 18 of the seat cushion 12. The pair of recliner mechanisms 24 is disposed between the first and second seat back brackets 44, 46 and the first and second seat cushion brackets 48, 50.

[0016] The seat assembly 10 also includes a head restraint 52 for comfort and for restricting head movement of the occupant during a motor vehicle impact. The head restraint 52 is slidably coupled to the upper cross member 40 of the seat back frame 30, as is described below in greater detail, and is movable vertically between a stowed position and a use position. When there is no occupant on the seat assembly 10, the head restraint 52 is in the stowed position, as shown in Figure 2. In the stowed position, the head restraint 52 is in a lowered position such that it is disposed adjacent to the upper end 20 of the seat back 14, thereby decreasing the overall height of the seat back 14. As a result, a driver is provided with an unobstructed view out the rear of the motor vehicle. Additionally, there is greater clearance between the head restraint 52 and a front seat (not shown) for pivoting the seat back 14 into a folded position, thereby increasing the stowage space within the motor vehicle. When there is an occupant on the seat assembly 10, the head restraint 52 is in the use position, as shown in Figure 1. In the use position, the head restraint 52 is in a raised position such that it is disposed upward and spaced apart from the upper end 20 of the seat back 14,

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707213PCT thereby increasing the overall height of the seat back 14 to provide the desired comfort and support for the occupant's head. It is appreciated that although the head restraint 52 is described with respect to a rear seat, the head restraint 52 may be coupled to any seat within the motor vehicle.

[0017] The seat assembly 10 further includes a mechanism, generally shown at 53, for automatically moving the head restraint 52 between the use position and the stowed position in response to detecting the presence and absence of an occupant on the seat assembly 10. More specifically, a pair of spaced apart head restraint posts 54, 56 is slidably guided by a pair of guide tubes 58, 60 fixedly secured to the upper cross member 40 of the seat back frame 30. Alternatively, it is appreciated that the guide tubes 58, 60 may be replaced by openings formed directly in the upper cross member 40 of a stamped or cast seat back frame without varying from the scope of the invention. The head restraint posts 54, 56 extend between and are fixedly secured to the head restraint 52 and a guide plate 62 that is disposed between the side members 32, 34 of the seat back frame 30.

[0018] In the current embodiment, only one head restraint 52 is shown. It is appreciated, however, that more than one head restraint 52 could be attached to the guide plate 62 without varying from the scope of the invention. In such alternative embodiments, each head restraint 52 includes a pair of head restraint posts 54, 56 extending between the respective head restraint 52 and the guide plate 62. It is further appreciated that each head restraint 52 may include a single head restraint post or more than a pair of head restraint posts.

[0019] Referring to Figure 3, a cylindrical collar 64 is fixedly secured to a back surface 66 of the guide plate 62. More specifically, the cylindrical collar 64 includes a threaded internal bore 68 and is mounted to the back surface 66 of the guide plate 62 such that the threaded internal bore 68 defines a vertical axis 69 extending therethrough. The vertical axis 69 is coincident with the vertical movement of the head restraint 52.

[0020] A gear box 70 is fixedly secured to the lower cross member 42 of the seat back frame 30. The gear box 70 is operatively coupled to a leadscrew 72 that extends vertically between the gearbox 70 and the cylindrical collar 64. The leadscrew 72 includes a threaded outer surface 74 threadably engaging the threaded internal bore 68 of the cylindrical collar 64 for translating rotational motion of the leadscrew 72 into linear motion of the cylindrical

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707213PCT collar 64. More specifically, rotation of the leadscrew 72 in a first direction causes the cylindrical collar 64, and therefore the guide plate 62, to move upward along the leadscrew 72. Alternatively, rotation of the leadscrew 72 in a second direction causes the cylindrical collar 64, and therefore the guide plate 62, to move downward along the leadscrew 72.

[0021] A motor 76 is provided for driving the head restraint 52 between the use and stowed positions. In the embodiment shown, the motor 76 is mounted to the lower cross member 42 of the seat back frame 30 and is located remotely from the gear box 70 adjacent to the side member 32 such that the motor 76 is out of the occupant comfort zone of the seat back 14. It is appreciated that the motor 76 can be mounted in any of a plurality of positions without varying from the scope of the invention. A flexible drive shaft or cable drive 78 is coupled between the motor 76 and the gearbox 70 such that activation of the motor 76 in a first direction causes the leadscrew 72 to rotate in the first direction. Alternatively, activation of the motor 76 in a second direction causes the leadscrew 72 to rotate in the second direction.

[0022] A controller 80 is mounted to the side member 32 of the seat back frame 30.

The controller 80 is electrically connected to the motor 76, upper and lower limit switches 82, 84, and a seat sensor 86. In the embodiment shown, the upper and lower limit switches 82, 84 are also mounted to the side member 32. More specifically, the upper and lower limit switches 82, 84 are spaced apart along the side member 32 such that the upper limit switch 82 is generally toward the upper cross member 40 and the lower limit switch 84 is generally toward the lower cross member 42. The upper and lower switches 82, 84 are triggered or actuated by the guide plate 62 when the head restraint 52 is in the use and stowed positions, respectively. The seat sensor 86 is disposed within the seat cushion 12 and is operative to detect the presence and absence of an occupant on the seat assembly 10.

[0023] Alternatively, the upper and lower limit switches 82, 84 could be replaced by any of a variety of switches or sensors to sense the head restraint 52 in the use and stowed positions. Further, the switches or sensors could be located in any of a variety of positions on the seat assembly 10. For example, a switch or sensor could be located at each end of the leadscrew 72 to detect the guide plate 62 at its limits of travel. It is also contemplated that the use and stowed positions of the head restraint 52 could be detected electronically such as by detecting a stall current of the motor 76, as is well known in the art.

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707213PCT [0024] In operation, starting with the seat back 14 in the seating position and the head restraint 52 in the stowed position, if the seat sensor 86 detects the presence of an occupant on the seat assembly 10 an occupant present signal Sl is sent to the controller 80 to activate the motor 76 to rotate in the first direction. The drive shaft 78 transfers the rotation of the motor 76 to the gearbox 70, which causes the leadscrew 72 to also rotate in the first direction. Rotation of the leadscrew 72 in the first direction urges the cylindrical collar 64 and therefore the guide plate 62 upward along the leadscrew 72, thereby moving the head restraint 52 from the stowed position to the use position, as shown in Figure 1. Once the head restraint 52 is in the use position, the guide plate 62 triggers the upper limit switch 82 and an upper limit signal S2 is sent to the controller 80 to deactivate the motor 76. With the head restraint 52 in the use position, the overall height of the seat back 14 is increased to provide comfort to and restrict occupant head movement.

[0025] If the occupant dismounts from the seat assembly 10 the seat sensor 86 detects the absence of the occupant and an empty seat signal S3 is sent to the controller 80 to activate the motor 76 to rotate in the second direction. The drive shaft 78 transfers the rotation of the motor 76 to the gearbox 70, which causes the leadscrew 72 to also rotate in the second direction. Rotation of the leadscrew 72 in the second direction urges the cylindrical collar 64 and therefore the guide plate 62 downward along the leadscrew 72, thereby moving the head restraint 52 from the use position to the stowed position, as shown in Figure 2. Once the head restraint 52 is in the stowed position, the guide plate 62 triggers the lower limit switch 84 and a lower limit signal S4 is sent to the controller 80 to deactivate the motor 76. With the head restraint 52 in the stowed position, the overall height of the seat back 14 is decreased to prevent interference between the head restraint 52 and the front seat when pivoting the seat back 14 into the folded position.

[0026] Referring to Figures 4 and 5, wherein like primed reference numerals represent similar elements as those described above, in an alternative embodiment of the invention the leadscrew 72' is replaced with a telescoping tube or strut 88. The telescoping tube 88 extends between the lower cross member 42' of the seat back frame 20' and the guide plate 62' and includes an outer member 90 slidably coupled to an inner member 92. The telescoping tube 88 includes a compression spring or other biasing mechanism 94 for biasing the outer and inner members 90, 92 apart from one another such that the telescoping tube 88 is normally extended, as shown in Figure 4.

7 707213PCT [0027] A hook 96 is pivotally coupled to an upper edge of the guide plate 62' at pivot

98. The hook 96 is biased to an engaged position by a hook spring 100 extending between the hook 96 and the guide plate 62'. In the engaged position, the hook 96 is latched to the seat back frame 20' to lock the head restraint 52' in the use position. More specifically, the upper cross member 40' of the seat back frame 20' includes a hole or aperture 102 formed therein for receiving the hook 96 when the head restraint 52' is in the use position. The engagement of the hook 96 with the seat back frame 20' prevents unwanted movement of the head restraint 52'. Specifically, the hook 96 prevents the head restraint 52' from moving downwardly during a motor vehicle impact.

[0028] A cable 104 is provided for actuating the hook 96 from the engaged position to a disengaged position to enable the telescoping tube 88 to compress. The cable 104 extends between a first end 106 fixedly secured to the hook 96 and a second end (not shown) operatively coupled to the motor 76'. The cable 104 extends downwardly from the hook 96 along or through the telescoping tube 88 and is guided by a pulley or other guide member 108 to the motor 76'. The pulley 108 is rotatably mounted on the lower cross member 42' adjacent the telescoping tube 88. The motor 76' winds the cable 104 to pivot the hook 96 in a clockwise direction (when viewed from Figure 4) from the engaged position to the disengaged position. In the disengaged position, the hook 96 is released from the seat back frame 20' which allows the telescoping tube 88 to be compressed to move the guide plate 62' downward in order to move the head restraint 52' to the stowed position, as shown in Figure 5.

[0029] The k value of the hook spring 100 is less than the k value of the tube spring

94. Thus, when the motor 76' winds the cable 104, the hook 96 will pivot from the engaged position to the disengaged position before the telescoping tube 88 is compressed to lower the head restraint 52'. Alternatively, when the motor 76' unwinds the cable 104, the telescoping tube 88 will extend to raise the head restraint 52' before the hook 96 is pivoted from the disengaged position to the engaged position.

[0030] In operation, starting with the seat back 14' in the seating position and the head restraint 52' in the stowed position, if the seat sensor 86' detects the presence of an occupant on the seat assembly 10' an occupant present signal Sl ' is sent to the controller 80' to activate the motor 76' to unwind the cable 104. As the cable 104 unwinds, the tube spring

94 causes the telescoping tube 88 to extend, which moves the guide plate 62' upward, thereby

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707213PCT moving the head restraint 52' from the stowed position to the use position. Once the head restraint 52' reaches the use position, the guide plate 62' triggers the upper limit switch 82' and an upper limit signal S2' is sent to the controller 80' such that the motor 76' continues to unwind the cable 104 a small amount to allow the hook 96 to pivot in a counterclockwise direction (when viewed from Figure 5) from the disengaged position to the engaged position. With the head restraint 52' in the use position, the overall height of the seat back 14' is increased to provide comfort to and restrict occupant head movement.

[0031] If the occupant dismounts from the seat assembly 10' the seat sensor 86' detects the absence of the occupant and an empty seat signal S3' is sent to the controller 80' to activate the motor 76' to wind the cable 104. As the cable 104 begins to wind the hook 96 pivots in the clockwise direction (when viewed from Figure 4) from the engaged position to the disengaged position. Once the hook 96 is disengaged from the seat back frame 20' continued winding of the cable 104 causes the telescoping tube 88 to compress. Compressing the telescoping tube 88 moves the guide plate 62' downward, thereby moving the head restraint 52' from the use position to the stowed position. Once the head restraint 52' reaches the stowed position, the guide plate 62' triggers the lower limit switch 84' and a lower limit signal S4' is sent to the controller 80' to deactivate the motor 76'. With the head restraint 52' in the stowed position, the overall height of the seat back 14' is decreased to prevent interference between the head restraint 52' and the front seat when pivoting the seat back 14' into the folded position.

[0032] It is contemplated that a other devices, such as a gas strut, could be used instead of the spring-biased telescoping tube 88 shown in Figures 4 and 5. A typical gas strut will lock-up in response to a quick or sharp impact. Therefore, the gas strut will prevent the head restraint 52' from moving downwardly during a motor vehicle impact and, as such, the hook 96 is not required.

[0033] 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.

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707213PCT

Claims

What is claimed:

1. A seat assembly for supporting an occupant in a motor vehicle, said seat assembly comprising:

a seat cushion;

a seat back coupled to said seat cushion;

a head restraint mounted to an upper end of said seat back for movement between a use position spaced apart from said upper end of said seat back and a stowed position adjacent said upper end of said seat back; and

a mechanism operative for automatically moving said head restraint between said use position and said stowed position in response to detecting the presence and absence of the occupant, said mechanism including a lead screw threadably engaged with said head restraint and a motor operatively coupled to said leadscrew for rotation thereof, wherein rotation of said leadscrew in a first direction in response to detecting the presence of the occupant moves said head restraint to said use position, and wherein rotation of said leadscrew in a second direction in response to detecting the absence of the occupant moves said head restraint to said stowed position.

2. A seat assembly as set forth in claim 1 including a seat sensor for detecting the presence and absence of the occupant.

3. A seat assembly as set forth in claim 2 wherein said seat sensor is disposed in said seat cushion.

4. A seat assembly as set forth in claim 3 including upper and lower limit switches for detecting said head restraint in said use position and said stowed position.

5. A seat assembly as set forth in claim 4 wherein said upper and lower limit switches are disposed in said seat back.

6. A seat assembly as set forth in claim 5 including a controller, wherein said controller is electrically connected to said motor, said seat sensor, and said upper and lower limit switches.

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707213PCT

7. A seat assembly as set forth in claim 6 wherein said head restraint is coupled to a guide plate and said leadscrew is threadably engaged with a cylindrical collar fixedly secured to said guide plate.

8. A seat assembly as set forth in claim 7 including a gear box and a drive shaft operatively coupled between said motor and said gear box, wherein said leadscrew is operatively coupled to said gear box for rotation in said first and second directions.

9. A mechanism operative for automatically moving a head restraint mounted to a seat back between a use position spaced apart from the seat back and a stowed position adjacent the seat back in response to detecting the presence and absence of an occupant on the seat assembly, said mechanism comprising:

a motor for providing rotational movement in a first direction and a second direction;

a gear box;

a drive shaft operatively coupled between said motor and said gear box for transmitting said rotational movement between said motor and said gear box; and

a leadscrew threadably engaged with said head restraint and operatively coupled to said gear box;

wherein said motor provides rotational movement in said first direction to rotate said leadscrew in said first direction in response to detecting the presence of the occupant, thereby moving said head restraint to said use position, and wherein said motor provides rotational movement in said second direction to rotate said leadscrew in said second direction in response to detecting the absence of the occupant, thereby moving said head restraint to said stowed position.

10. A seat assembly for supporting an occupant in a motor vehicle, said seat assembly comprising:

a seat cushion;

a seat back coupled to said seat cushion;

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707213PCT a head restraint mounted to an upper end of said seat back for movement between a use position spaced apart from said upper end of said seat back and a stowed position adjacent said upper end of said seat back; and

a mechanism operative for automatically moving said head restraint between said use position and said stowed position in response to detecting the presence and absence of the occupant, said mechanism including a telescoping tube extending between said head restraint and said seat back, a motor, and a cable operatively coupled between said head restraint and said motor, wherein operation of said motor in response to detecting the presence of the occupant lengthens said cable, thereby allowing said telescoping tube to extend and moving said head restraint to said use position, and wherein operation of said motor in response to detecting the absence of the occupant shortens said cable, thereby compressing said telescoping tube and moving said head restraint to said stowed position.

11. A seat assembly as set forth in claim 10 wherein said telescoping tube includes a first spring having a first k value for biasing said telescoping tube to extend.

12. A seat assembly as set forth in claim 11 wherein said head restraint is coupled to a guide plate and said telescoping tube extends between said guide plate and said seat back.

13. A seat assembly as set forth in claim 12 including a hook pivotally coupled to said guide plate for pivotal movement between an engaged position engaging said seat back when said head restraint is in said use position to prevent unwanted downward movement of said head restraint and a disengaged position released from said seat back.

14. A seat assembly as set forth in claim 13 including a second spring having a second k value for biasing said hook to said engaged position.

15. A seat assembly as set forth in claim 14 wherein said cable is operatively coupled between said hook and said motor for actuating said hook from said engaged position to said disengaged position.

16. A seat assembly as set forth in claim 15 wherein said second k value of said second spring is less than said first k value of said first spring, whereby shortening said cable

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707213PCT pivots said hook from said engaged position to said disengaged prior to compressing said telescoping tube.

17. A seat assembly as set forth in claim 16 whereby lengthening said cable allows said telescoping tube to extend prior to pivoting said hook from said disengaged position to said engaged position.

18. A seat assembly as set forth in claim 17 including a pulley rotatably mounted to said seat back for guiding said cable between said hook and said motor.

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7Q7213PCT