Note: Descriptions are shown in the official language in which they were submitted.
PNEUMATIC SEAT SUPPORT WITH LINKAGE
AND HORIZONTAL SHOCK ABSORBERS
BACKGROUND OF THE INVENTION
This invention relates to pneumatic supports or suspensions for vehicle
seats and particularly to suspensions having conventional pneumatic shock ab-
sorbers for support and for controlling bounce and linkages for positioning
the shock absorbers horizontally.
Gas spring suspensions for vehicle seats are shown in U.S. patent No.
4,105,195 issued to Ervins H. Lamberts on August 8, 1978, in U.S. patent No.
3,736,020 issued to Pilachowsky et al. on May 29, 1973, and in U.S. patent
No. 4,087,069 issued to Hall et al. on May 2, 1978. Lamberts' seat support
has an elongated, vertical air cushion with a special height control to admit
air from a pressurized source for greater height and to discharge air to at-
mosphere for lower height. Pilachowsky's support is also vertically oriented
and has a particular mounting for snowmobiles, and Hall's namely horizontal
support utilizes drums and cables requiring much lateral space available un-
der bench-type automobile seats. These supports are not compact enough to fit
between frames and seats of motorcycles, and neither do they have opposing
spring devices for controlling bounce.
SUMMARY OF THE INVENTION
In an embodiment according to the present invention, two commercially
available pneumatic shock absorbers and a linkage comprising levers and gears
are arranged in a narrow horizontal space. The linkage and shock absorbers
are then compact enough vertically to fit between the seat and the frame of
a motorcycle. One of the shock absorbers namely supports a loaded seat, and
the other shock absorber functions to apply force in a downward direction for
controlling bounce. The linkage changes the direction of the controlling
force of the plungers of the shock absorbers from horizontal to vertical.
An air pump connected to the cylinder of the supporting shock is oper-
ative to pressurize the supporting shock for providing a desired intermediate
height of the seat as required to support the weight of one or two occupants
of the seat. Since each of the shock absorbers are connected through the
same or similar linkages to the seat, the pressure in the shock absorber Eor
control of bounce is less than that in the shock absorber providing the sup-
port. In the preferred embodiment, the supporting force is proportional to
the difference in pressures within the cylinders of the shock absorbers.
The seat support according to this invention may be modified by using
a compression, helical spring in place of the second shock absorber. Other
optional features are additional springs in series in the linkage connecting
the shock absorbers to the seat. Either the preferred embodiment requiring
minimal vertical space as required for motorcycles, or another embodiment
with slightly greater height can be used in other vehicles such as snow-
mobiles.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a fragmentary, oblique, rear, right side view of a motorcycle
showing an attached seat support of the present invention;
FIG. 2 is a schematic, oblique, front, right side view of the support of
FIG. l;
FIG. 3 is an enlarged view of a portion of FIG. 1 with its seat frame
exploded upward;
FIG. 4 is an enlarged view of a lower end of a lever supporting the seat
frame of FIG. 2 to show a resilient coupling; and
FIG. 5 is a fragmentary, oblique, rear, right side view of supporting
pneumatic shock absorbers and linkage of another embodiment, this linkage
being useable in place of the linkage shown in FIG. 2 wherever a seat support
for various kinds of vehicles can have slightly greater height than the low
height suitable for motorcycles.
DESCRIPTION OF THE PREFERRED EMBODDMENT
As shown in FIG. 1, a seat support 11 according to the present invention
has a seat frame 12 below the rear portion, the portion for a passenger, of a
motorcycle seat 13. A linkage 14 shown in FIG. 2 is located below the seat
frame 12, and shock absorbers 15 and 16 extend rearward and substantially
horiæontally from just below the lower rear edge of the seat frame 12 to a
30 support frame 17. A support frame 17 has interconnected portions 17a, 17b,
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(FIG. 1) and 17c (FIG. 3) removably fastened to frame lo oE the motorcycle.
The rear or passenger's portion of a conventional seat 13 fits down over
the seat frame 12 and the slightly lower operator's portion projects forward
in front of the seat frame 12. As described below with reference to FIG. 3,
a linear, ball bushing bearing is utilized in a guide to permit free vertical
motion of the seat frame 12 in spite of leverage caused by weight being in
front.
As shown in FIGS. 1 and 2, each of the pneumatic shock absorbers 15 and
16 have a rear end of a cylinder connected to the motorcycle frame 18 by bring
connected to a rod 19 of the seat frame 17a. The plungers of the shock ab-
sorbers 15 and 16 are connected to respective opposite ends of a lever 20 of
the linkage 14. The lever 20 is connected to a set of miter gears 21 to move
in unison seat-supporting levers 22 and 23 connected between the set of gears
21 and the seat frame 12. Summarizing, the shock absorbers 15 and 16 may be
considered to be spring devices connected in series with the linkage 14 to the
seat frame 12. The linkage 14 provides stable, resilient support for the
seat frame 12 as controlled by the shock absorbers 15 and 16 and permits the
shock absorbers to be positioned horizontally such that the complete seat
support 11 can be positioned below a motorcycle seat to maintain the seat at
its normal level.
In detail, a rod 24 connected to the outer end of the plunger of the
shock absorber 15 is connected rotatively to the right end of the lever 20
(FIG. 3,). As shown, for particular applications, the rod 24 may be curved
downwardly such that the lever 20 may be somewhat below the level of the
shock absorbers 15 and 16. The center of the lever 20 (FIG. 2) is connected
to the lower end of a vertical shaft, the shaft extending upward into a gear
box 26 (FIG. 3) and connected axially to a miter gear 27 (FIG. 2). The oppo-
site end of the lever 20 is likewise connected by a rod 28 attached to the
plunger of the shock absorber 16 such that when the seat frame is being forced
downward, the plunger of the shock absorber 15 is being retracted while the
plunger of the shock absorber 16 is being extended.
The miter gear 27 that is rotated by the lever 20 is meshed with
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longitudinally opposite miter gears 29 and 30, the gear 29 having a horizon-
tal shaft 31 extending Eorward out of the gear box, and the gear 30 having a
horizontal shaft 32 extending rearward. The outer ends of the shafts 31 and
32 are either fastened rigidly to the lower ends of respective levers 22 and
23 respectively or fastened through a resilient coupling 33 shown in FIG. 4
described below. Since the shafts 31 and 32 extend in opposite directions
irom their respective miter gears 29 and 30 and the lever 22 extends upwardly
to the left while the lever 23 extends upwardly to the right, the upper ends
of the levers 22 and 23 are always at an even level regardless of height as
controlled by operation of the lever 20 and the gears 27, 29, and 30. For
supporting the seat -Erame 12, the upper ends of the levers 22 and 23 are
coupled to opposite ends of the seat frame through pillow blocks 34 and 35.
As shown in FIG. 2, a shaft 36 extends laterally inward from a turned-down
edge of the right side of the seat frame 12 and fits through the bearing of
the pillow block 35. Likewise, a similar shaft is connected to the left side
of the seat frame 12, and the bearing of the pillow block 34 is a sliding fit
about the shaft. The upper end of the lever 22 is pivoted about the longitud-
inal axis of the left pillow block 34 by a pivot 37, and likewise the right
pillow block 35 is pivotally coupled to the upper end of the lever 23. The
distances of the lateral, sliding movements of the pillow blocks 34 and 35
are quite short, and obviously the proportions including the length of the
levers 22 and 23 must be chosen such that the blocks 34 and 35 do not contact
the adjacent turned down edges of the seat frame 12 before the frame lZ is in
its lowest, desired position.
The weight of the operator and any passenger on the motorcycle seat 13
(FIG. 1) is namely supported by the right pneumatic shock absorber 15(FIG. 2),
and rebound or bounce is controlled by the le-ft pneumatic shock absorber 16.
A usual air pump 38 controlled by a switch 39 has its output connected select-
ively through a two-way valve 40 to the cylinders of the pneumatic shock ab-
sorbers 15 and 16. Since the plùnger oE the shock absorber 15 is retracted to
a greater extent by adding weight to the seat 11, the shock absorber 15 is pro-
vided with the greater pressure, and the shock absorber 16 is provided with
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sufficient air to control bounce most effectively. Since the height of the
seat 13 is proportional to the difference in pressures within the shocks 15
and 16, the pressures are to be adjusted alternately. An air bleeding valve
(not shown) for each of the shock absorbers 15 and 16 is provided.
As shown in FIG. 3, the vertical guide comprises namely a strong shaft
41 depending vertically from an upper end fastened rigidly near the right,
front corner to the lower surface of the seat frame 12, and a heavy-duty,
linear ball bushing bearing 42 attached rigidly to the support frame 17 for
receiving the shaft 41. An additional optional guide comprises a flat bar,
depending from the rear edge of the seat frame 12 near the left, rear corner,
and a roller 44 connected by a fore-to-aft adjusting screw 45 to the longitud-
inal, central member 17a of the support frame. The roller has a lateral,
horizontal axis, and its fore-to-aft position is adjusted by the screw 45 in
a usual manner to have the roller bear against the rear surface of the bar
43. The position of the roller 44 must be carefully adjusted such that it is
retracted a very short distance after it has been positioned forward enough
to cause the least noticeable binding of the shaft 41 in the linear bearing
42.
For still greater resilience, the coupling 33 of FIG. 4 is used to
couple each of the shafts 31 and 32 of the set of gears 21 (FIG. 2) to the
respective levers 22 and 23. With particular reference to the front lever 22,
the normally lower end of its edge that faces a downward slanting direction is
extended a moderate distance beyond the shaft 31, and the lower end of this
extended portion 46 has a slot midway between the sides of the portion 46 to
accommodate the insertion of a shank of a machine bolt 47 parallel to the
sides of the lever 22 and perpendicular to its lower slanting edge. The shaft
31 extends through the lever 22 -hat is rotative on the shaft, and a short
coupling lever 48 is rigidly secured to the end of the shaft 31 adjacent the
outer side of the lever 22. The coupling lever 48 extends from the shaft 31
to a position adjacent the slotted portion 46 and has an upper portion 49
curved over and spaced from the slotted portion 46. A helical compression
spring 50 is inserted between the slotted portion 46 and the upper portion 49
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such that the bolt 47 can be inserted through a hole of the upper portion 493
through the coils of the spring 50 and the slot in the end of the portion 46.
The bolt 47 is tightened to compress the spring 50 a desired amount for a
comfortable ride.
The strength of the similar springs 50 connected to levers 22 and 23 is
chosen such that the springs are substantially compressed by the weight of
the occupants of the seat 13. The springs operate effectively on a motor-
cycle to cushion the occupants while the motorcycle is traveling quite rap-
idly over moderately smooth highways such as arterial highways. Under this
condition the pneumatic shock absorbers may operate too slowly, and anyway
their operation is not required because the faster springs have sufficient
travel for the rapid short excursions. At slower speeds or over rougher
roads, the pneumatic shock absorbers themselves smoothen the ride materially,
and the springs 50 cooperate with the shock absorbers to lower the seat 13
smoothly as the wheels of the motorcycle have just passed over a bump.
A different linkage 51 shown in FIG. 5 may be substituted for the link-
age 14 of FIG. 2 to provide a seat support with slightly greater height.
Since the use of the linkage 51 on motorcycles would usually require the pas-
senger seats to be elevated somewhat, this simpler linkage is more suitable
for use in snowmobiles and other vehicles. In FIG. 5, angular levers 52 and
53 replace the levers 20, 22, and 23 of FIG. 2~ and a set of spur gears 54
replace the set of miter gears 21.
The lower end of a lower straight portion of the lever 52 is pivotally
connected to the plunger of the pneumatic shock absorber 15; the intermediate
angular portion is connected to a shaft 55 of a spur gear 56 within the set
54; and the outer, or front, end of the lever 52 is pivotally connected to the
pillow block 35. The spur gear 56 is meshed with the spur gear 57, and the
shaft of the gear 57 is connected to the immediate angular portion of a lever
53. The lever 53 and its connections are similar to the lever 52 and its con-
nections; the lower end of the lever being connected to the plunger of thepneumatic shock absorber 16, and the outer, or rear end being connected to
the pillow block 34. Rather than having the upper and the lower straight
v
portions of each of the levers 52 and 53 welded rigidly together at an angle,
the upper portion may be separate and be coupled by two spaced members and a
spring as suggested by the coupling 33 in FIG. 4. The lower straight portion
of each lever 52 or 53 and a member corresponding to the member or coupling
lever 48 would be secured rigidly to a shaft of a corresponding spur gear 56
or 57, and a member corresponding to the extended end of the lever 22 could
be secured to the inner end of the upper portion of each lever 52 or 53. As
described above with reference to FIG. 4, a spring and adjusting bolt between
the members corresponding to the members 46 and 48 would provide additional
resilience.
Both embodiments of a seat support shown in FIGS. 2 and 5 may be modi-
fied by substituting a helical spring assembly for the pneumatic shock ab-
sorber 16. The helical spring assembly may be the type where a rod to be con-
nected in place of the plunger of the pneumatic shock absorber extends through
the spring to connect to the opposite end of the spring such that the spring
is compressed as the rod is extended. Then both the spring and the shock ab-
sorber 15 operate simultaneously to increase resistance to downward movement
of the seat frame 12.
