Vehicle seat having lumbar support

An automobile seat backrest includes an adjustable lumbar support assembly for selectively applying pressure to the lower area of a seated occupant's back. The backrest portion has a structural frame and a wire mesh within the frame for supporting a foam cushion. A cover envelopes the frame, wire mesh and cushion. First and second cranks are moveably supported on the wire mesh within the cover of the backrest portion. Cantilever arms extend from the respective first and second cranks to carry corresponding first and second applicator pads. A manual actuator causes the applicator pads to move in a synchronized fashion toward respective extended positions applying outward pressure to the cover. The manual actuator includes a twist knob which controls a worm gear, and a drum having gear teeth that mesh with the worm gear. A conduit extends from the actuator to the first crank, and a core element, slidably disposed within the conduit, interconnects the twist knob and the second crank. The actuator simultaneously applies a tensile force along the core element and a complimentary compressive force along the conduit to move the first and second cranks and to thereby displace the first and second applicator pads in unison against the cover, thus providing variable lumbar support to a seated occupant.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The subject invention relates generally to an adjustable lumbar support 
mechanism concealed within the backrest portion of a seat, and in 
particular a cable operated mechanism for use in an automobile seat 
assembly. 
2. Description of Related Art 
For ergonomic and therapeutic reasons, it is desirable to provide 
adjustable support to the lower lumbar region of a person's back when 
seated for long periods of time. As automobile driving often entails long 
seated periods with only limited movement, lumbar support mechanisms are a 
welcome addition to many automobile seat assemblies. The lumbar support 
mechanisms must be adjustable in view of the varying body sizes and shapes 
of automobile drivers and passengers, as well as the desire to alter one's 
seat conditions from time to time. 
The prior art has advanced many types of adjustable lumbar support 
mechanisms for the automobile seat environment, including both manually 
adjusted and powered adjusted units. To help maintain costs low and weight 
down, manually adjusted lumbar support mechanisms are more often preferred 
over the powered versions. Examples of manually adjusted lumbar support 
mechanisms may be had by reference to U.S. Pat. No. 5,076,643, to 
Colasanti et al., issued Dec. 31, 1991, and U.S. Pat. No. 5,088,790, to 
Wainwright et al., issued Feb. 18, 1992, both assigned to the assignee of 
the subject invention, the disclosures of which are hereby incorporated by 
reference. While nearly all prior art manually adjusted lumbar support 
mechanisms function satisfactorily, there remains the ever-present desire 
to further reduce both cost and weight, while maintaining and/or 
increasing durability, functionality and assembly. 
SUMMARY OF THE INVENTION 
The subject invention comprises an automobile seat assembly including a 
backrest portion having a structural frame and a cover enveloping the 
frame. First and second applicator pads are supported within the cover of 
the backrest portion for generally synchronized movement toward respective 
extended positions applying outward pressure to the cover. A first crank 
is operatively connected to the first applicator pad, and a second crank 
is operatively connected to the second applicator pad. A conduit connects 
to the first crank, and a core element is slidably disposed within the 
conduit and connected to the second crank. The improvement of the subject 
invention comprises an actuator which simultaneously applies a tensile 
force along the core element and a complimentary compressive force along 
the conduit to move the first and second cranks and thereby displace the 
first and second applicator pads in unison against the cover, thus 
providing lumbar support to a seated occupant. 
The subject invention also contemplates an adjustable lumbar support 
assembly for selectively applying pressure to the lower area of a seat 
backrest. The assembly comprises a first support wire, a second support 
wire spaced parallel from the first support wire, a first applicator pad 
pivotally supported on the first support wire, a second applicator pad 
pivotally supported on the second support wire, a first crank operatively 
connected to the first applicator pad, a second crank operatively 
connected to the second applicator pad, a conduit operatively connected to 
the first crank, and a core element slidably disposed within the conduit 
and operatively connected to the second crank. The improvement of the 
invention comprises an actuator operatively connected to the conduit and 
the core element for applying a tensile force along the core element and a 
complimentary compressive force along the conduit to simultaneously move 
the first and second cranks and thereby displace the first and second 
applicator pads in unison against the cover providing lumbar support to a 
seated occupant. 
The subject actuator results in a manually adjusted lumbar support 
mechanism which is particularly inexpensive to construct and substantially 
lighter than the prior art designs. The subject design is also very 
durable and can be readily installed in most existing seat constructions.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the Figures, wherein like numerals indicate like or 
corresponding parts throughout the several views, an automobile seat 
assembly is generally indicated at 10. The seat assembly 10 includes a 
generally vertical backrest portion 12 and a horizontal seat portion 14. 
The backrest portion 12 has a tubular frame 16 positioned along its inner 
periphery. The backrest portion 12 is filled with a foam-type cushion 18, 
which is supported within the frame 16 by a suspension mat-type wire mesh 
20, as is known to those skilled in the art. The frame 16, cushion 18 and 
wire mesh 18 are all enveloped by a decorative cover 22 made of fabric, 
leather or other material. The wire mesh 20 is best shown in FIGS. 2 and 
3. 
A lumbar support assembly is generally shown at 24 in FIGS. 2-5 for 
selectively applying pressure to the lower area of the backrest portion 
12. The lumbar support assembly 24 includes first 26 and second 28 
applicator pads positioned beneath the fabric cover 22 and foam cushion 18 
of the backrest portion 12. The first and second applicator pads 26, 28 
are pivotally supported within the backrest portion 12 for generally 
synchronized movement toward an extended position (right half of FIG. 4) 
applying outward pressure to the cover 22. The first and second applicator 
pads 26, 28 are oriented so as to apply pressure on opposite sides of a 
seated occupant's spine, in the lower back region. The first and second 
applicator pads 26, 28 are each fabricated from a plastic material and 
include a plurality of apertures formed therein for weight and cost 
reduction purposes. 
The first and second applicator pads 26, 28 each include an arm 30, 32, 
respectively, extending laterally therefrom. The arms 30, 32 each comprise 
a pair of rod-like beams are fabricated from a heavy gauge wire material. 
In the preferred embodiment shown in the Figures, the applicator pads 26, 
28 are rigidly connected to the arms 30, 32. However, those skilled in the 
art will readily appreciate that in an alternative embodiment the 
applicator pads 26, 28 may be articulated or otherwise flexibly connected 
to the arms 30, 32. 
As shown in FIGS. 2-5, the arms 30, 32 are fixedly connected to respective 
first and second cranks 34, 36. Therefore, the first crank 34 is 
operatively connected to the first applicator pad 26 and the second crank 
36 is operatively connected to the second applicator pad 28. The two 
cranks 34, 36 are identical in construction, thereby minimizing 
production, tooling and inventory costs, and are preferably fabricated 
from a durable plastic material. Each crank 34, 36 includes an arcuate (or 
otherwise rounded) rim 38 which is grooved much like the rim of a pulley 
sheave. The cranks 34, 36 are independently supported for movement upon a 
bearing surface 40, which surrounds a vertically extending axle section 42 
of wire(s) in the wire mesh 20. The bearing surface 40 permits either 
relative rotation between the cranks 34, 36 and the axle section 42 of the 
wire mesh 20, or as in the case of the embodiment as shown in FIGS. 3-5 
the bearing surface 40 non-rotatably grips a pair of side-by-side wires, 
thereby using the inherent torsion spring properties of the wires. In 
either case, each crank 34, 36 is independently pivotal about an axis 
(generally vertical) defined by the axle section 42 of the wire(s) of the 
wire mesh 20. As each crank 34, 36 pivots, its associated arm 30, 32 and 
connected applicator pad 26, 28 swings an arc either toward or away from 
the lower back of an occupant seated in the seat assembly 10. 
Those skilled in the art will appreciate that in an alternative embodiment, 
the cranks 34, 36 can be supported for rotation on a yoke-like support or 
other feature of the frame 16, instead of the wire mesh 20. In this 
application (not shown), the lumbar support assembly is fully independent 
of the wire mesh 20. 
An actuator, generally indicated at 44 in FIGS. 1-5, is provided for 
selectively manipulating the applicator pads 26, 28 so that an occupant 
can adjust the amount and degree of lumbar support. The actuator 44 may 
take any general form, including electric motor and/or pressurized fluid 
power assisted, as will become apparent to those skilled in the art. 
However, the actuator 44 preferably comprises a manual input device 
described in detail below. 
A flexible motion transmitting remote control assembly transmits motion and 
forces between the cranks 34, 36 and the actuator 44. The motion 
transmitting remote control assembly includes a sheath-like conduit 46 
which slidably supports an internal moving core element 48. The conduit 46 
may be of the composite type having an inner tubular liner defining the 
internal boundaries of a core passage, at least one metallic supportive 
lay wire wrapped helically about the liner, and an outer cover disposed 
about the lay wire. However, any such conduit construction or Bowden-type 
actuator will perform satisfactorily. The core element 48 may be either a 
single wire or a plurality of wire filaments wrapped helically to form a 
single motion transmitter. 
The conduit 46 includes one end 50 operatively connected to the first crank 
34, in a pocket thereof. The connection between the one end 50 of the 
conduit 46 and the first crank 34 allows compressive forces to be 
transferred therebetween and resists disconnection. An opposite end 52 of 
the conduit 46 is operatively connected to a housing of the actuator 44, 
as by a clamp or other such fastener. A curved section 54 forms in the 
conduit 46 between the actuator 44 and the first crank 34. In order for 
the applicator pads 26, 28 to properly pivot upon manipulation of the 
actuator 44, there must be an unrestrained bow 54 in the conduit 46, as 
will be more fully described below. 
One end of the core element 48 is operatively connected to the second crank 
36 via a slug 56 seated in a corresponding notch, as best shown in FIG. 5. 
The other end 58 of the core element 48 is operatively connected to the 
actuator 44, such that manipulation of the actuator 44 causes displacement 
of the core element 48 within the conduit 46. Referring to FIGS. 3-5, the 
core element 48 is shown extending unsheathed from the one end 50 of the 
conduit 46, around the rim 38 of the first crank 34, through the interior 
of the backrest portion 12, around the rim 38 of the second crank 36, and 
finally to the slug 56. The core element 48 slides over the rim 38 of the 
first crank 34, and imparts no significant forces thereto. 
The actuator 44 functions by applying a tensile force along the core 
element 48 and at the same time a complimentary compressive reaction force 
along the conduit 46. This contemporaneous pulling force on the core 
element 48 and pushing force on the conduit 46 simultaneously rotates the 
first 34 and second 36 cranks and thereby displaces the first 26 and 
second 28 applicator pads in unison against the cover 22 to provide lumbar 
support to a seated occupant. The compressive force is generated along the 
conduit 46 by a reaction of the curved section 54 tending to straighten 
out as the core element 48 is tensioned. As a result, the compressive 
forces are met with immovable resistance at the end 52 anchored to the 
housing of the actuator 44, via its attachment to the frame 16, while the 
end 50 butted against the first crank 34 is yieldable via the bearing 
surface 40 axle section 42 interface. 
As stated above, the actuator 44 preferably includes a manual input device. 
The manual input device may include a twist knob 60, and a drum 62 
operatively disposed between the one end 58 core element 48 and the twist 
knob 60. The twist knob 60 includes a worm gear 64 and the drum 62 
includes gear teeth 66 operatively meshing with the worm gear 64. Rotation 
of the twist knob 60 drives the drum 62, which in turn winds and unwinds 
the core element 48 depending upon direction of rotation. This results in 
an increase or decrease in the tensile forces applied to the core element 
48. Changes in the mechanical advantage of the twist knob 60 can be 
effected by varying the pitch of the worm gear 64 and/or the pitch circle 
diameter of the drum gear teeth 66. 
In operation, the applicator pads 26, 28 are at the unactuated position 
shown in the left half of FIG. 4. When the occupant desires to increase 
the level of pressure exerted by the applicator pads 26, 28, he or she 
rotates the twist knob 60 any desired number of revolutions within the 
range of movement of the components. This causes the core element 48 to 
begin pulling the second crank 36 via the abutment of the slug 56. This, 
in turn, pivots the second crank 36 about its wire axle 42 in a clockwise 
direction as viewed from the right half of FIG. 4, and swings the 
associated applicator pad 28 into pressing engagement with the occupant's 
lower back. As the core element 48 is tensioned, and effectively 
shortened, the bowed section 54 of the conduit 46 is urged to straighten 
itself. This action of the conduit 46 results in a compressive force being 
transmitted along its length, thereby reacting against the first crank 34 
and causing it to pivot in the counter clockwise direction, thus swinging 
its associated applicator pad 26 into pressing engagement with the 
occupant's lower back. 
Accordingly, both applicator pads 26, 28 swing simultaneously into the 
lower back region of the occupant as the actuator 44 is manipulated. The 
actuator 44 restrains the core element 48 relative to the conduit 46, via 
the worm gear 64 arrangement, thus effectively locking the applicator pads 
26, 28 in any displaced position. When it is desired to return the 
applicator pads 26, 28 to their unactuated position (as shown in the left 
half of FIG. 4), the twist knob 60 is rotated in the reverse direction 
while the occupant gently leans rearwardly against the applicator pads 26, 
28, thereby forcing the system to return to its home condition. 
The lumbar support assembly can be adapted to provide a range of 
responsiveness to the occupant. For example, by altering the length of the 
arms 30, 32 and the shape/size of the applicator pads 26, 28, different 
comfort responses can be achieved. Likewise, by moving the assembly 
vertically relative seat frame 16, variations in the comfort can be 
realized. Furthermore, by altering the material and/or diameter of the 
arms 30, 32, it is possible to increase or decrease their rigidity. In 
some applications, it may be desirable to limit flexibility of the arms 
30, 32, whereas in other situations a high degree of flexibility may be 
preferred. Similarly, the position of the arms 30, 32 relative to their 
respective applicator pads 26, 28 has an effect on the flexibility within 
and along each of the applicator pads 26, 28. For example, in the 
preferred embodiment, the uppermost and lowermost regions of the 
applicator pads 26, 28 will likely experience some deflection during use. 
If this is undesirable, the respective pairs of arms 30, 32 can be spread 
apart further to more fully reinforce the associated applicator pads 26, 
28. 
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. 
Obviously, 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, wherein reference 
numerals are merely for convenience and are not to be in any way limiting, 
the invention may be practiced otherwise than as specifically described.