SEMI ACTIVE HEIGHT ADJUSTER

BACKGROUND

[0001] This invention relates in general to a semi active height adjuster and, more specifically, to a semi active drive mechanism for use with a seat height adjuster for actively raising and passively lowering the elevation of a seat assembly.

[0002] A seat height adjuster may be incorporated in a vehicle seat enabling an occupant to selectively adjust the elevation of the seat assembly according to his or her physique and seating posture. The seat height adjuster generally includes an actuator or drive mechanism to provide means for actuating an adjustable seat support frame.

Conventionally, a ratchet-type or stepping-type lever mechanism has been employed which utilizes a known ratchet gear configuration including a ratchet gear and drive pawl. With this mechanism, an occupant can simply pivot an operation lever repeatedly in an upward or downward direction so that a rotational force is transmitted to the adjustable support frame for selectively adjusting the vertical elevation of the seat to a desired level.

[0003] It is known to provide a drive mechanism for use with a seat height adjuster for active adjustment in the upward direction and passive adjustment in the downward direction. For example, there is disclosed in U.S. Patent No. 6,422,651 to Muhlberger et al. a stepping mechanism for a seat height adjuster, wherein the automobile seat is raised upward in a pumping motion by means of a lever. The downward directed adjustment of the seat occurs by a downward movement of the lever. The downward movement may then occur in one step assisted only by the force exerted by gravity. The stepping mechanism includes a gear mounted for rotation and a pawl operative for rotating the gear. The pawl is connected to a guide bar and capable of pivoting coaxially with a manually activated lever. A friction spring is incorporated for releasing the pawl from the gear when the lever is pivoted in the downward direction. To prevent unwanted rotation of the seat height adjuster assembly, a freewheel-type clutch mechanism is mounted to the seat height adjuster.

[0004] While known drive mechanisms for seat height adjusters work for their intended purposes, there is a need for an improved drive mechanism for actively raising and passively lowering the elevation of a vehicle seat assembly.

SUMMARY OF THE INVENTION

[0005] This invention relates to an improved semi active drive mechanism for use with a seat height adjuster for actively raising and passively lowering the elevation of the seat. The semi active drive mechanism includes a drive gear having a plurality of ratchet teeth. The drive gear is mounted for rotation about a central axis intersecting a support plate. A lever is pivotally mounted about the central axis relative to the support plate and drive gear. A spring is configured to bias the lever in a neutral position. A drive pawl is pivotally mounted to the lever for engaging and rotating the drive gear in a first direction. The drive pawl includes a cam pin configured to slide along a cam surface for operatively pivoting the drive pawl. A locking pawl is pivotally mounted to the support plate. The locking pawl is configured to engage the drive gear and prevent rotation of the drive gear in a second direction. The lever further includes a guide pin configured to contact and pivot the locking pawl.

[0006] Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Fig. 1 is a side elevation view of a vertically adjustable seat assembly including a semi active drive mechanism in accordance with this invention.

[0008] Fig. 2 is an enlarged perspective side view of the semi active drive mechanism illustrated in Fig. 1. [0009] Fig. 3 is a further enlarged side elevational view of portions of the semi active drive mechanism illustrated in Figs. 1 and 2.

[0010] Fig. 4 is a side elevational view similar to Fig. 3 showing the operation of the semi active drive mechanism when the lever is initially pivoted in the upward direction.

[0011] Fig. 5 is a side elevational view similar to Figs. 3 and 4 showing the operation of the semi active drive mechanism when the lever is further pivoted in the upward direction.

[0012] Fig. 6 is a side elevational view similar to Figs. 3, 4, and 5 showing the operation of the semi active drive mechanism when the lever is initially pivoted in the downward direction.

[0013] Fig. 7 is a side elevational view similar to Figs. 3, 4, 5, and 6 showing the operation of the semi active drive mechanism when the lever is further pivoted in the downward direction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Referring now to the drawings, there is illustrated in Fig. 1 a vertically adjustable seat assembly 1 including a seat support frame 5 and a seat height adjuster, indicating generally at 3, in accordance with this invention. The seat assembly 1 may be utilized in various seating applications, including the passenger compartment of an automobile. The seat height adjuster 3 may be selectively operated by hand with the use of a semi active drive mechanism, indicated generally at 10.

[0015] As illustrated in Figs. 2 and 3, the semi active drive mechanism 10 includes a support plate 12. In a central portion of the support plate 12, there is formed a center hole through which a center shaft 18 is supported for rotation about a central axis 24. A pinion gear (not shown) is fixed for rotation to the center shaft 18 and is operatively connected to the seat height adjuster 3. A lever, indicated generally at 30, is pivotally mounted about the center shaft 18. A drive gear 22 is fixed for rotation on the center shaft 18 about the central axis 24. A detent member or drive pawl 40 is mounted on the lever 30 by a connecting pin 48 and is pivotal about a second axis 46. The drive pawl 40 is configured to selectively engage the drive gear 22. A locking pawl 50 is mounted to the support plate 12 by a connecting pin 54 and is pivotal about a third axis 56. The locking pawl 50 is also configured to selectively engage the drive gear 22. It should be appreciated that the semi active drive mechanism 10 may be arranged in a variety of configurations other than as specifically illustrated without departing from the scope of the present invention.

[0016] The support plate 12 rigidly supports the semi active drive mechanism 10 on the seat frame 5. The support plate 12 may be formed from a generally flat plate or other substantially rigid material and can be shaped as necessary for a desired application. The support plate 12 is mounted to the seat assembly 1, such as to the seat frame 5, using any suitable method conventional in the art. For example, the support plate 12 can include a plurality of attachment holes 16 that can be used to securely fasten the semi active drive mechanism 10 to the seat frame 5.

[0017] As described above, the semi active drive mechanism 10 includes a center shaft 18 that is supported for rotation by the support plate 12 about a central axis 24. The central axis 24 intersects and is generally perpendicular to the support plate 12. The center shaft 18 is configured to support the pinion gear (not shown) and the drive gear 22 for fixed rotation relative to the support plate 12. Accordingly, when the center shaft 18 is operatively rotated, the elevation of the seat assembly 1 is adjusted in the vertical direction.

[0018] The lever 30 is pivotally mounted about the center shaft 18 and extends in a plane generally parallel to the support plate 12. The lever 30 is pivotal about the central axis 24 relative to the center shaft 18 and support plate 12. A lever arm 36 is mounted to the lever 30 and configured to apply a moment about the central axis 24. The lever arm 36 generally extends forward in the driving direction and is accessible to the hand of an occupant in the seat assembly 1. It should be appreciated that the lever arm 36 may be formed as part of the lever 30 or may be a separate component integrated or mounted to the lever 30. The lever 30 further includes a guide pin 52 mounted thereto and located a radial distance from the center axis 24. The purpose of the guide pin 52 will be discussed below. As shown in Fig. 2, the lever 30 may be composed of a pair of plate like members or the like located a spaced distance apart and mounted to one another for additional support and stability of the lever 30.

[0019] As shown in Fig. 2, a spring 32 interacts with the lever 30 and the support plate 12 to bias the lever 30 in a neutral position N (shown in Fig. 3) relative to the support plate 12. In the illustrated embodiment, the spring 32 is a circular or rotary return spring having a first leg 34a and a second leg 34b.' Both the first leg 34a and the second leg 34b encompass opposing ends of a lug 37 fixed to the lever 30 and a lug 38 fixed to the supporting plate 12. This configuration encourages the lever 30 to return to the neutral position N each time the lever 30 is pivoted and released, as will be explained. It should be appreciated, however, that any suitable method for biasing the lever 30 in the neutral position N may be employed without departing from the scope of the invention.

[0020] The drive gear 22 is fixed for rotation on the center shaft 18 and extends in a plane generally parallel to the support plate 12. The drive gear 22 may be mounted to the center shaft 18 using any suitable method conventional in the art including, for example, a press fit or spline connection. The drive gear 22 includes a plurality of ratchet-type gear teeth 26. The ratchet teeth 26 are angled in one direction to enable rotation of the drive gear 22 in a first direction and to prevent rotation of the drive gear 22 in a second direction when operatively engaged by a detent or pawl member. For example, in the illustrated embodiment as shown in Fig. 3, the ratchet teeth 26 are configured to normally permit clockwise rotation of the drive gear 22 relative to a pawl member and to normally prevent counter-clockwise rotation of the drive gear 22. The ratchet teeth 26 may be located along the outer periphery of the drive gear 22 so as to be easily accessible by a pawl member. The rotation of the drive gear 22 will be discussed in greater detail below.

[0021] As described above, the drive pawl 40 is mounted on the lever 30 by the connecting pin 48 and is pivotal about the second axis 46. The drive pawl 40 is radially spaced from the center axis 24 and extends in the same plane as the drive gear 22 so as to be selectively pivoted into and out of engagement with the drive gear 22. The free end of the drive pawl 40 is configured to fittingly engage with the ratchet teeth 26 of the drive gear 22. For example, the free end of the drive pawl 40 may be shaped to engage the ratchet teeth 26 or may include at least one ratchet-type tooth. The drive pawl 40 includes a cam pin 42 that is spaced from the second axis 46. The cam pin 42 is configured to slide along a cam surface, indicated generally at 44, whenever the lever 30 is pivoted about the central axis 24. The cam pin 42 and cam surface 44 operatively pivot the drive pawl 40 about the second axis 46, as will be discussed in greater detail below. In the illustrated embodiment, the cam surface 44 is located along an adjacent edge of the support plate 12. However, the cam surface 44 may be located along any other available surface relative to the lever 30. The drive pawl 40 is pivotally biased about the second axis 46 such that the cam pin 42 remains in continuous contact with the cam surface 44. The drive pawl 40 may be biased using any method conventional in the art, including a spring or the like (not shown).

[0022] As mentioned above, the locking pawl 50 is mounted to the support plate 12 by the connecting pin 54 and is pivotal about the third axis 56. The locking pawl 50 is spaced from the central axis 24 and extends in the same plane as the drive gear 22 so as to be selectively pivoted into and out of engagement with the drive gear 22. The free end of the locking pawl 50 is configured to fittingly engage with the ratchet teeth 26 of the drive gear 22. In the illustrated embodiment, the locking pawl 50 includes at least one ratchet-type tooth 58. The ratchet tooth 58 is angled in a direction so as to fittingly engage with the ratchet teeth 26 of the drive gear 22. The locking pawl 50 is pivotally biased about the third axis 56 for engagement with the drive gear 22 using any method conventional in the art, including a spring or the like (not shown). When engaged with the drive gear 22, the locking pawl 50 allows rotation of the drive gear 22 in a first direction and prevents rotation in a second direction. For example, in the illustrated embodiment as shown in Fig. 3 the locking pawl 50 permits clockwise rotation of the drive gear 22 and prevents counter-clockwise rotation of the drive gear 22 when engaged with the drive gear 22.

[0023] Operation of the semi active drive mechanism 10 will now described in detail. As shown in Fig. 3, if the lever 30 is initially in the neutral position N, the guide pin 52 contacts and secures the locking pawl 50 into full engagement with the drive gear 22. When in full engagement, the locking pawl 50 prevents rotation of the drive gear 22 in the counter-clockwise direction. Furthermore, when the lever 30 is in the neutral position N, the cam pin 42 and cam surface 44 are configured to prevent the drive pawl 40 from engaging with the drive gear 22.

[0024] To raise the seat assembly 1 to a desired elevation, the occupant pivots the lever 30 in an upward direction (indicated by UP in Figs. 4 and 5) from the neutral position N, as shown in Fig. 4. When the lever 30 is pivoted in the upward direction, the guide pin 52 is rotated about the central axis 24 and away from contact with the locking pawl 50. As a result, the locking pawl 50 is no longer in full engagement with the drive gear 22. As discussed above, the locking pawl 50 will remain biased for engagement with the drive gear 22, allowing clockwise rotation of the drive gear 22 as indicated by the arrow while preventing counter-clockwise rotation. Furthermore, when the lever 30 is initially pivoted in the upward direction, the cam pin 42 and cam surface 44 are configured to operatively engage the drive pawl 40 with the drive gear 22. To

accomplish this, the cam surface 44 includes a stepped profile angled radially inward towards the central axis 24, causing the free end of the drive pawl 40 to be pivoted towards and into engagement with the drive gear 22. The lever 30 and cam surface 44 are configured to rotate the drive pawl 40 coaxially about the central axis 24 in

formfitting engagement with the drive gear 22. The drive gear 22 is rotated in a clockwise direction, as indicated by the arrow, over a distance in the upward pivoting direction of the lever 30. Rotation of the drive gear 22 in the clockwise direction operates to raise the seat assembly 1. As best illustrated in Fig. 5, when the lever 30 is further pivoted in the upward direction, the drive pawl 40 continues to rotate the drive gear 22 in a clockwise direction further raising the seat assembly 1.

[0025] When the lever 30 is pivoted back towards the neutral position N from an upward position, the locking pawl 50 remains biased for engagement with the drive gear 22, thereby preventing counter-clockwise rotation of the drive gear 22. The free end of the drive pawl 40 is configured to slide over the ratchet teeth 26 relative to the drive gear 22 in the counter-clockwise direction. Thus, performing an active cranking motion in the upward direction allows an occupant to selectively raise the seat assembly 1 to achieve a desired elevation.

[0026] To lower the seat assembly 1, the seat occupant pivots the lever 30 in a downward direction (indicated by DN in Figs. 6 and 7) from the neutral position N, as shown in Fig. 6. When the lever 30 is initially pivoted in the downward direction, the guide pin 52 is rotated about the central axis 24 away from contact with the locking pawl 50. It should be noted that when the lever 30 is moved in a downward position, the drive pawl 40 remains disengaged from the drive gear 22. Referring now to Fig. 7, when the lever 30 is further pivoted in the downward direction, the guide pin 52 contacts the locking pawl 50 and is configured to pivotally disengage it from the drive gear 22. When disengaged, the drive gear 22 is allowed to rotate in the counter-clockwise direction as indicated by the arrow. The seat height adjuster 3 is configured such that the weight of the seat assembly 1 and occupant on the seat causes the seat assembly 1 to passively lower without the application of additional force.

[0027] When the lever 30 is pivoted back towards the neutral position N from a downward position, the guide pin 52 contacts and pivots the locking pawl 50 back into full engagement with the drive gear 22. As discussed above, full engagement of the locking pawl 50 with the drive gear 22 prevents rotation of the drive gear 22 and stops vertical movement of the seat assembly 1. This allows the occupant to selectively lower the seat assembly 1 to achieve a desired elevation. [0028] It should be fully appreciated that the semi active drive mechanism 10 may be configured such that the pivoting direction of the lever 30 will have a reverse effect on the direction of adjustment of the seat assembly 1. For example, if the lever 30 is actively pivoted in the downward direction, the seat assembly 1 will be raised, and if the lever 30 is pivoted in the upward direction, the seat assembly 1 will be passively lowered.

[0029] In accordance with the provisions of the patent statues, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.