Note: Descriptions are shown in the official language in which they were submitted.
CA 02465748 2004-04-29
VEHICLE SEAT WITH DUAL INDEPENDENTLY ADJUSTABLE SUPPORTS
Field of the Invention
S The present invention relates to a vehicle seat constructed with two
separate
seat cushions, wherein each seat cushion is supported in a generally vertical
direction by
compressed air, and each cushion is supported laterally in both the fore and
aft direction, and
in the side to side direction, by mechanical means. One seat cushion,
hereinafter referred to as
the "inner seat cushion", is shaped and positioned to support the occupant's
pelvic area
directly below the base of the spine. The other seat cushion, hereinafter
referred to as the
"outer seat cushion", is shaped and positioned to support the backside of the
occupant's thighs
and the outer areas of the buttocks. A control valve in the air supply line to
each cushion
permits the occupant to regulate the height of each cushion independently from
the other
cushion. Furthermore, the outer cushion may be mounted on an adjustable sub-
structure
attached to the outer cushion support means so as to permit the occupant to
vary the amount of
support to the lower thighs provided by the outer seat cushion.
BackQaround of the Invention
In the prior art, it is common practice for heavy duty vehicle seats to be
constructed on a sub-base with a pivoted parallelogram linkage and a
compressed air actuator
supporting the seat cushion in position above a fixed base, and with an
adjusting valve to
regulate the air supply to the air actuator, thereby permitting the occupant
of the seat to adjust
the ride height of the seat. Such prior art vehicle seats as described above
provide a wide
range of height adjustment, and the ability to absorb much more of the energy
from severe
jolts than is possible with a simple rigid seat with foam padding or with air
bladder style seat
cushions. Operators of trucks and off highway mobile equipment are required to
spend many
hours each working day subjected to continual bouncing and vibration, while in
a sitting
position, resulting in a high incidence of related injuries such as chronic
lower back pain and
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circulatory deficiencies among such workers. In a seated posture, the
occupant's body weight
is centered over the pelvis, while the legs extend laterally forward of the
torso. The pressure
between the seat cushions and the driver's body is distributed most
predominantly in the area
of the pelvis, thus transmitting most of the seating pressure directly through
the pelvis directly
into the spine. As seat cushions conform to the shape of the occupant's body
parts, which are
in supportive contact with the seat cushions, there is a reduction of blood
circulation in those
areas, and fatigue in the joints such as the lower vertebrae, which are
subjected to continual
compression. Furthermore, because the body weight is supported mainly through
the pelvis,
the weight of the occupant's legs and lower torso adds to the total weight
supported by the
base of the spine.
In the prior art, various seats with a plurality of portions which can be
varied
with respect to form and hardness have been proposed. Such seats are disclosed
in US patent
#5,263,765, Hideyuki Nagashima, and US patent #5,320,409, Ka,zuhito Katoh, in
which a
plurality of inflatable bladders are strategically positioned within the seat
and are selectively
inflated and deflated under the control of a fatigue sensing means. Such seats
could offer
relief from fatigue caused by continual seat pressure and vibration, but they
do not address the
absorption of large impacts related to vehicle operation on bumpy terrain and
highways.
Summary of the Invention
The apparatus of the present invention constitutes an improvement over the
prior art by permitting the occupant of the seat to adjust the pressure
distribution of the seat
against the occupant's body parts from time to time, while maintaining the
soft ride
characteristics of a pivoted linkage type of seat. In a preferred embodiment
of the present
invention, hereinafter alternatively referred to as a "dual ride seat", an
inner seat including its
cushion is mounted on a first sub-base supported by a first air actuator, and
retained laterally
by a lower parallelogram linkage configured so that by adding air into the
first air actuator, the
inner seat including its cushion and the outer seat including its cushion are
caused to rise
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approximately vertically with respect to the vehicle floor. The pressure of
the air in the first
air actuator is adjusted manually to balance the weight of the occupant plus
the two cushion
assemblies at a ride height of the occupant's choosing. The inner seat and
cushion is shaped
and positioned to support the pelvic area directly below the base of the spine
of a person sitting
on the seat. An outer seat and its cushion is mounted on a second sub-base
supported by a
second air actuator, and retained laterally by an upper parallelogram linkage
configured so that
by adding air into the second air actuator, the outer seat and cushion is
caused to rise
approximately vertically with respect to the inner seat and cushion. The
pressure of the air in
the second air actuator is adjusted manually to change the amount of the
occupant's weight
supported by the outer seat and its cushion assembly. The outer seat and its
cushion is shaped
and positioned to support the backside of the thighs and the outer areas of
the buttocks of the
occupant. By manually adjusting the ride height of the outer cushion with
respect to the inner
cushion, the occupant can change the pressure distribution from completely
supported by the
inner cushion against the pelvis and consequently directly through the base of
the spine, to
1 S completely supported by the thighs and outer buttock areas and indirectly
to the spine through
the hips.
When the body is supported solely by the outer cushion, the weight of the legs
and lower torso is taken directly through the seat, thus reducing the load
transmitted through
the pelvis and the lower spine, and the upper body weight is supported in a
more naturally
balanced manner through the hips. When the body is supported solely by the
outer cushion,
the effective spring rate of the seat system is reduced to approximately one
half of that of a
single seat system, due to the arrangement of two air actuators acting in
tandem. A damping
device such as a hydraulic shock absorber may be connected between the base
and either of the
seat sub-bases so as to dampen repetitive oscillations of the seat cushions in
the vertical
direction. The provision for independent height adjustment of the outer
cushion with respect
to the inner cushion from time to time, permits the occupant to re-distribute
the seat pressure
so as to allow blood circulation to be maintained more properly, and to vary
the load pattern in
the joints and in the lower vertebrae. Furthermore, the outer cushion may be
mounted on a
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pivoted plate with an adjusting means to vary the amount of support provided
to the lower
thighs.
The present invention may thus offer the following advantages over prior art:
a) The ability to support the occupant's body weight entirely through the
thighs and outer areas of the buttocks, with provision to adjustably support a
portion or all of
the body weight directly through the pelvis and base of the spine.
b) The ability to maintain good blood circulation in the body parts which
are in supportive contact with the seat, by redistributing support pressure
from time to time.
c) The ability to reduce long term joint fatigue in the lower back and pelvic
areas, by redistributing support pressure from time to time.
d) The ability to absorb more impact energy caused by travel over rough
terrain than prior art seats may offer, by means of a lower effective spring
rate of the seat
system, utilizing an arrangement of two air actuators acting in tandem to
support the outer seat
cushion.
In summary, the present invention is a vehicle seat with dual independently
adjustable supports including an inner seat disposed for supporting the lower
spine and
adjacent inner buttocks region of a user sitting in the vehicle seat and an
outer seat having a
generally U-shape when viewed in plan form and mounted so as to surround the
inner seat,
disposed so as to support the thighs and outer buttocks region of the user.
Means are mounted
to the inner seat for selectively raising and lowering the inner seat. Means
are mounted to the
outer seat for selectively raising and lowering the outer seat. Horizontal
stabilizing means
horizontally stabilize vertical movement of the inner and outer seat. Control
means cooperate
with the means mounted to the inner seat for selectively raising and lowering
the inner seat, for
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controlling the vertical position of the inner seat. Control means cooperate
with the means
mounted to the outer seat for selectively raising and lowering the outer seat,
for controlling the
vertical position of the outer seat. Support means are mounted to a support
base for supporting
the means mounted to the inner seat and the means mounted to the outer seat
for selectively
raising and lowering the inner and outer seats respectively. The means mounted
to the inner
and outer seats for selectively raising and lowering the inner and outer seats
respectively serve
as a pair of resilient means acting in tandem to resiliently support the inner
and outer seats.
The inner and outer seats may be mounted on inner and outer sub-plates
respectively. In one embodiment the outer sub-plate is pivotally mounted to an
outer seat
platform. A pivot angle of the outer sub-plate is adjusted by an adjusting
means which may
include at least one cam mounted on a rotatable pivot shaft mounted to the
outer seat platform.
The cam in such an embodiment may have an array of flat faces thereon such
that the
adjustable sub-plate is supported at any one time by one flat face of the cam.
Each flat face of
the array of flat faces of the cam provides for a different the pivot angle
for the adjustable sub-
plate.
An adjustable resilient support may be mounted to the inner seat andlor the
outer seat. The spring support may include an air actuator, which may itself
include an air
spring. The air actuator may be mounted so as to act between the support base
and the inner
seat such that the inner seat is raised with respect to the support base when
the air actuator is
extended, or may be mounted so as to act between the inner seat and the outer
seat such that
the outer seat is raised with respect to the inner seat when the air actuator
is extended, or may
be mounted so as to act between the support base and the outer seat such that
the outer seat is
raised with respect to the support base when the air actuator is extended.
Resiliently damping
shock absorbers may be mounted so as to act between the support base and the
outer seat, and
between the support base and the inner seat.
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The stabilizing device may include a first parallelogram linkage of pivotally
mounted arms so as to allow the inner seat to remain substantially horizontal
as it moves in
an arc determined by the pivoting of the first parallelogram, where a first
end of the first
parallelogram is pivotally mounted to the support base, and an opposite second
end of the
parallelogram is pivotally mounted to the inner seat. The stabilizing device
may also include a
second parallelogram linkage of pivotally mounted arms so as to allow the
outer seat to remain
substantially horizontal as it moves in an arc determined by the pivoting of
the second
parallelogram, where a first end of the second parallelogram is pivotally
mounted to the outer
seat, and an opposite second end of second parallelogram is pivotally mounted
to either the
inner seat or the support base.
The inner and outer seat may include a seat cushion having at least ane
inflatable bladder element.
Brief Description of the Drawings
The invention will be better understood by reference to the accompanying
drawings, wherein:
Figure 1 depicts in right side an elevation view a dual ride seat apparatus
according to a preferred embodiment of the present invention.
Figure 2 is a right side elevation view as in Figure 1, depicting the seat in
a first
raised position.
Figure 3 is a right side elevation view as in Figure 1, depicting the seat in
a
second raised position.
Figure 4 is a plan view of the seat of Figure 1, depicting the layout of the
seat
cushions.
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Figure 5 is a right side elevation view according to a second preferred
embodiment of the dual ride seat of the present invention.
Figure 6 is, in front perspective view, a further embodiment of the seat of
Figure 1.
Figure 7 is, in front elevation view, the seat of Figure 6.
Figure 8 is, in rear elevation view, the seat of Figure 6.
Figure 9 is, in left side elevation view, the seat of Figure 6.
Figure 10 is, in right side elevation view, the seat of Figure 6.
Figure 11 is, in plan view, the seat of Figure 6.
Detailed Description of Embodiments of the Invention
As best seen in Figs. 1, 2 and 3, according to a preferred embodiment of the
present invention, the inner seat cushion 1, shown in partially dotted outfine
in Figures 1 and 2,
is mounted on a first sub-base 2. First sub-base 2 is suspended by being
pivotally mounted to
two pairs of lower parallel arms 3 and 4, wherein the pair of lower parallel
arms 3 comprise a
pair of arms of which only the near arm is visible as drawn, and wherein lower
parallel arms 4
comprise a pair of arms of which only the near arm is visible as drawn, and
wherein the lower
two pair of parallel arms 3 and 4 are pivotally attached to a fixed base 5.
Pins 6 permit free
rotation of the lower parallel arms 3 and 4 in a vertical plane only,
perpendicular to the pin 6
axis. A first air actuator 7 is mounted between the first sub-base 2 and the
lower pair of
parallel arms 4 so that air pressure, when admitted to the first air actuator
7 causes the first
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sub-base 2 to be lifted with respect to the base 5 as the force generated by
the first air actuator
acts through the first sub-base 2, the two pairs of lower parallel arms 3 and
4, and the base 5.
Air supply to the first air actuator 7 is controlled by a manually operated
first valve 8, and
routed to the first air actuator 7 via tubing and fittings 9. Compressed air
may be provided
from an air brake system compressor, or from a separate compressor mounted in
the vehicle,
not shown in the drawings. An outer seat cushion 10 is pivotally attached to a
second sub-base
11, which is suspended by pivotally mounted two pairs of upper parallel arms
12 and 13,
wherein the pair of upper parallel arms 12 comprise a pair of arms of which
only the near arm
is visible as drawn, and wherein the two pair of upper parallel arms 12 and 13
are pivotally
attached to the first sub-base 2. Pins 6 permit free rotation of the upper
parallel arms 12 and
13 in a vertical plane only, perpendicular to the pin 6 axis. A second air
actuator 14 is
mounted between the second sub-base 11 and the first sub-base 2 so that air
pressure, when
admitted to the second air actuator 14 causes the second sub-base 11 to be
lifted with respect
to the first sub-base base 2 as the force generated by the second air actuator
acts through the
second sub-base 11, the two pairs of parallel arms 12 and 13, and the first
sub-base 2. Air
supply to the second air actuator 14 is controlled by a manually operated
second valve 15 via
tubing and fittings 23.
In operation, the dual ride seat apparatus is lowered to an entry/exit
position as
depicted in Fig. l, wherein the first air actuator 7 and the second air
actuator 14 are in a
substantially retracted state. When an occupant is seated, the occupant
manually actuates
valve 8 to cause air to be supplied to the first air actuator 7. As the first
air actuator 7 extends,
the first sub-base 2 is caused to raise, and consequently both the inner seat
cushion 1 and the
outer seat cushion 10 are raised together, as depicted in Fig. 2. When the
occupant of the seat
chooses to increase the support to the occupant's thighs and outer buttocks,
the occupant
manually actuates valve 15 to cause air to be supplied to the second air
actuator 14. As the
second air actuator 14 extends, the second sub-base l l is caused to raise,
and consequently the
outer seat cushion 10 is raised with respect to the first sub-base 2, as
depicted in Fig. 3. To
summarize the operation of the seat, the first valve 8 controls the overall
ride height of the dual
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ride seat, while the second valve 15 controls the distribution of support of
the occupant's body,
between the inner seat cushion 1 and the outer seat cushion 10. The outer seat
cushion 10 is
mounted on a sub-plate 16, which is pivotally attached to the second sub-base
11 by pins 17 so
that the sub-plate 16 may rotate in a vertical plane parallel with the plane
of rotation of the
S pairs of parallel arms 3, 4, 1 l, and 12. Sub-plate 16 is supported at the
opposite end from the
pins 17 by a multi-faced cam 18. Cam 18 is supported by bearings 19 which are
mounted on
the second sub-base 11. A crank arm 20 is connected to cam 18 so as to permit
the occupant
of the seat to rotate the cam 18 thereby incrementally changing the angle of
the sub-plate 16
with respect to the sub-base 11. Seat back 21 is attached to the second sub-
base 11 by
attaching means commonly used in commercial seat construction. A damping
device 22 such
as a commercial shock absorber is attached between the second sub-base 11 and
the base 5 to
damp out oscillations, which would occur due to the spring nature of the first
air actuator 7 and
the second air actuator 14. A similar second damping device, not shown in the
drawings, may
be applied similarly between the base 5 and the first sub-base 2 so as to
increase the total
damping effect.
In a second preferred embodiment of the present invention, not shown in the
drawings, all elements remain as described in the first preferred embodiment,
with the
exception of the positioning of the second air actuator 14 and the pairs of
upper parallel arms
12 and 13. The second air actuator is mounted so as to act between the second
sub-base 11
and the base 5. The second sub-base 11 is suspended by pivotally mounted two
pairs of upper
parallel arms 12 and 13, and the two pairs of upper parallel arms are
pivotally attached to the
base 5. In this second preferred embodiment, the inner seat cushion 1 and the
outer seat
cushion 10 are manually adjusted completely independently. The air actuators 7
and 14 do not
act in tandem, and the overall ride height is adjusted by the operation of
both valves 8 and 15.
An advantage of this second embodiment is the possibility of reducing the
overall height of the
seat in its lowest position.
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In the embodiments of Figures 6-11, the chair is laterally stabilized by
pivotally
mounted cross-struts. In particular, cross-struts 30-35 are pivotally mounted
between,
respectively: fixed base 5 and first sub-base 2 for cross-struts 30 and 31;
first sub-base 2 and
second sub-base 11 for cross-strut 32; fixed base vertical frame member 24 and
seat back
frame 21a for cross-strut 33; and, first sub-base vertical frame member 25 and
second sub-base
11. Vertical frame members 24 and 25 are rigidly mounted to fixed base 5 and
first sub-base 2
respectively. Shoulder supports 26 and support back 27 are pivotally mounted
to vertical
supports 21b rigidly mounted to frame 21a.
As will be apparent to those skilled in the art in the light of the foregoing
disclosure, many alterations and modifications are possible in the practice of
this invention
without departing from the spirit or scope thereof. Accordingly, the scope of
the invention is to
be construed in accordance with the substance defined by the following claims.
