U.S. patent number 3,632,077 [Application Number 05/038,275] was granted by the patent office on 1972-01-04 for variable damping means.
This patent grant is currently assigned to Universal Oil Products Company. Invention is credited to Garth O. Hall, Harvey N. Tengler.
United States Patent |
3,632,077 |
Hall , et al. |
January 4, 1972 |
VARIABLE DAMPING MEANS
Abstract
A variable damping means for cushioning a vehicle occupant from
shocks and vibrations transmitted through the vehicle chassis. The
occupant support is allowed to oscillate with low damping to
provide maximum isolation for the occupant from light vibrations.
In addition, the occupant is cushioned with respect to severe
shocks by increased damping. The damping characteristics are
changed automatically as the character of the shocks and vibrations
changes.
Inventors: |
Hall; Garth O. (New Berlin,
WI), Tengler; Harvey N. (New Berlin, WI) |
Assignee: |
Universal Oil Products Company
(Des Plaines, IL)
|
Family
ID: |
21899012 |
Appl.
No.: |
05/038,275 |
Filed: |
May 18, 1970 |
Current U.S.
Class: |
248/566;
297/344.19; 248/631; 267/131; 188/285; 267/117 |
Current CPC
Class: |
B60N
2/527 (20130101); B60N 2/505 (20130101); B60N
2/502 (20130101); B60N 2/522 (20130101); B60N
2/501 (20130101) |
Current International
Class: |
B60N
2/52 (20060101); B60N 2/50 (20060101); B60n
001/02 () |
Field of
Search: |
;248/400,399,372,378,157
;267/131,117 ;188/285,299 ;297/345 ;280/124F |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Foss; J. Franklin
Claims
We claim as our invention:
1. A variable damping device for use in hydraulically cushioning a
vehicle occupant comprising:
a. a vehicle frame,
b. an occupant support vertically movable with respect to said
vehicle frame,
c. a first hydraulic cylinder interposed between said vehicle frame
and said occupant support,
d. a closable valve connected by a fluid transfer line to said
first hydraulic cylinder,
e. a pressurized hydraulic fluid reservoir connected to said
closable valve, thereby providing a passageway closable by said
closable valve between said first hydraulic cylinder and said
hydraulic fluid reservoir,
f. a flow regulating link operably connected to said closable valve
and operable by movements of sad occupant support, whereby said
link moves and operates said closable valve when said occupant
support moves in at least one direction,
g. a second hydraulic cylinder interposed between said flow
regulating link and said vehicle frame,
h. a hydraulic fluid line leading from said second hydraulic
cylinder,
i. a constrictive valve connected to said hydraulic fluid line,
j. a check valve connected to said hydraulic fluid line in parallel
with said constrictive valve, whereby said check valve allows
hydraulic fluid to flow in one direction with respect to said
hydraulic cylinder, and
k. a pressurized hydraulic fluid reservoir connected to said
constrictive valve and to said check valve.
2. The variable damping device of claim 1 further characterized in
that said constrictive valve is an adjustable valve.
3. The variable damping device of claim 1 further characterized in
that an actuating arm is attached to said occupant support and is
engageable with said flow regulating link, whereby said arm engages
said link and causes said link to move when said occupant support
moves in at least one direction.
4. The variable damping device of claim 3 further characterized in
that said actuating arm causes said flow regulating link to rotate
when said occupant support moves downward.
5. The variable damping device of claim 4 further characterized in
that said closable valve is comprised of a cylinder member having
an interior radial port, a second port, and a passageway
therebetween, and a sleeve member having a radial port alignable
with said interior radial port of said cylinder member, and one of
the aforesaid members is rigidly attached to said flow regulating
link.
6. The variable damping device of claim 3 further characterized in
that said closable valve is a needle valve comprised of a needle
member and an orifice member, and one of said members is operably
connected to said flow regulating link and the other of said
members is fixed relative to said vehicle frame.
7. The variable damping device of claim 3 further characterized in
that said actuating arm engages said flow regulating link when said
occupant support is in the lower portion of an oscillatory cycle
with respect to said vehicle frame.
8. A variable damping device for use in hydraulically cushioning a
vehicle occupant comprising:
a. a vehicle frame,
b. an occupant support vertically movable with respect to said
vehicle frame,
c. a first hydraulic cylinder interposed between said vehicle frame
and said occupant support,
d. a closable valve connected by a fluid transfer line to said
first hydraulic cylinder,
e. a pressurized hydraulic fluid reservoir connected to said
closable valve, thereby providing a passageway closable by said
closable valve between said first hydraulic cylinder and said
hydraulic fluid reservoir,
f. a flow regulating link operably connected to said closable valve
and operable by movements of said occupant support, whereby said
link moves and operates said closable valve when said occupant
support moves in at least one direction,
g. a second hydraulic cylinder interposed between said flow
regulating link and said occupant support,
h. a hydraulic fluid line leading from said second hydraulic
cylinder,
i. a constrictive valve connected to said hydraulic fluid line,
j. a check valve connected to said hydraulic fluid line in parallel
with said constrictive valve, whereby said check valve allows
hydraulic fluid to flow in one direction with respect to said
hydraulic cylinder, and
k. a pressurized hydraulic fluid reservoir connected to said
constrictive valve and to said check valve.
9. A variable damping device for use in hydraulically cushioning a
vehicle occupant comprising:
a. a vehicle frame,
b. an occupant support vertically movable with respect to said
vehicle frame,
c. a hydraulic cylinder interposed between said vehicle frame and
said occupant support,
d. a valve housing containing a passageway therethrough and a
blocking valve located in said passageway and connected to said
hydraulic cylinder by a fluid transfer line,
e. a pressurized hydraulic fluid reservoir in communication with
said passageway,
f. a barrier panel with respect to which said valve housing is
relatively movable, and said barrier panel is located in said
hydraulic fluid reservoir transverse to the direction of relative
motion of said valve housing, whereby relative movement of said
valve housing causes movement of said hydraulic fluid in said
hydraulic fluid reservoir and said barrier panel restricts the
movement of said hydraulic fluid,
g. a check valve that spans said barrier panel and allows easy
passage of hydraulic fluid in one direction while opposing passage
of hydraulic fluid in the opposite direction, and
h. flow regulating linkage connected to said occupant support and
operably connected with a relatively large minimum clearance to
said valve housing, whereby movement of said occupant support
operates said blocking valve only after said linkage moves beyond
the limit of said minimum clearance.
10. The variable damping device of claim 9 further characterized in
that there is an opening extending transversely through said
barrier panel and said check valve is located in said opening.
11. The variable damping device of claim 10 further characterized
in that said valve housing and said hydraulic fluid reservoir are
confined within a cylindrical sleeve member, and said valve housing
has a cylindrical central portion and at least one end portion of
segmental cross section only slightly smaller than a semicircle
having the same radius, and a transverse separation panel with a
passageway therethrough is located adjacent a first segmental end
portion of said valve housing in said hydraulic fluid reservoir,
and said barrier panel is a planar rectangle radially extending
from the axis of said sleeve member to the inner surface of said
sleeve member coextensive with and positioned generally opposite
said first segmental end portion of said valve housing and
intersecting said transverse separation panel within said sleeve
member.
12. The variable damping device of claim 11 further characterized
in that a second end portion of said valve housing is of segmental
cross section only slightly smaller than a semicircle having the
same radius, and an adjacent end of said flow regulating linkage is
of segmental cross section only slightly smaller than a semicircle
having the same radius and is located in said sleeve member
generally opposite said second end portion of said valve housing,
thereby creating the aforesaid minimum clearance between said valve
housing and said flow regulating linkage.
13. The variable damping device of claim 11 further characterized
in that a second end of said valve housing has a circular surface
and an adjacent end of said flow regulating linkage is coaxial with
said valve housing and has a circular surface, and a first of the
aforesaid circular surfaces has at least one track extending in an
arc about the axis of said valve housing abruptly terminated by an
obstacle at one end and smoothly blending into said first circular
surface at the other end, and at least one guide follower protrudes
from a second of the aforesaid circular surfaces and is spring
biased toward said first of the aforesaid circular surfaces and
engages said track, whereby relative rotation of said adjacent end
of said flow regulating linkage with respect to said valve housing
creates an operable connection between said flow regulating linkage
and said blocking valve only when rotation of said guide follower
is resisted by said obstruction.
14. The variable damping device of claim 11 further characterized
in that a second end of said valve housing and an adjacent end of
said flow regulating linkage are axially aligned and are connected
by an axially extending torsion bar.
15. The variable damping device of claim 11 further characterized
in that a second end of said valve housing and an adjacent end of
said flow regulating linkage are axially aligned within said sleeve
member and terminate in parallel elliptical faces slightly
separated from each other, thereby creating said minimum clearance.
Description
A variable damping means for cushioning a vehicle occupant from
shocks and vibrations transmitted through the vehicle chassis. The
occupant support is allowed to oscillate with low damping to
protect the occupant from light vibrations. In addition, the
occupant is cushioned with respect to severe shocks by increased
damping. The damping characteristics are changed automatically as
the character of the shocks and vibrations changes.
This invention is normally used as part of a seat suspension for
the driver of a heavy-duty vehicle, although it is appropriate for
use with any vehicle which subjects the operator to vibration. The
occupant support which is cushioned is normally the support for the
driver or operator of the vehicle, though the invention may
similarly be used to enhance the comfort of other occupants of the
vehicle. The invention is directed both toward use in the
suspension of vehicle seats and for use in suspending an operator
cab or other occupant compartments of a vehicle.
In conventional vehicle seat or cab suspensions, the occupant
support of a vehicle is normally biased away from the vehicle frame
through the use of conventional spring means, including air
cushions, air-oil suspension systems, and the like. These spring
means cause the occupant to undergo oscillation as the vehicle is
subjected to shocks and vibrations while traveling on a road,
track, or over other terrain. Since conditions can occur which
cause the oscillation of the occupant support to exceed the vehicle
oscillation, the occupant suspension systems are frequently
augmented with damping devices to reduce the amplitude of
oscillation to which the occupant is subjected. The conventional
damping devices are normally comprised of single or multiple shock
absorbers having fixed damping characteristics. Shock absorbers
having the most desirable damping characteristics are positioned
between the vehicle frame and the occupant support so as to allow a
slight amount of oscillation and yet dampen extremely hard jolts to
which the vehicle is subjected. This optimizing arrangement using
damping devices having fixed damping characteristics is far from
satisfactory, however, particularly in vehicles which sometimes
operate on smooth roads and at other times operate in rough
terrain. Instead of providing optimum comfort under such
conditions, these damping devices subject the vehicle occupant to a
rather hard ride on smooth surfaces and still provide inadequate
control of oscillations at large amplitudes when the vehicle is
traveling over rough terrain. To solve this problem, several
attempts have been made to produce a seat suspension having
variable damping, but no workable system of automatic variable
damping has yet been achieved.
It is an object of this invention to provide completely automatic
variable damping in a vehicle occupant suspension system. The
change in damping characteristics is automatic whether the damping
is being changed from light to heavy cushioning or whether it is
being changed from heavy to light cushioning. The purpose of
providing variable damping in a vehicle occupant suspension system
is to reduce the amplitude of oscillation of the occupant support
when the vehicle undergoes severe shocks but to do so without
creating a hard ride for the vehicle occupant when the vehicle is
subjected to light vibrations.
It is another object of this invention to provide a wide range of
adjustments to both the heavy and light damping or shock absorbing
characteristics of the variable damping system. The damping
characteristics may be made to vary continuously throughout the
operation of the vehicle, but preferably are changed only when the
vehicle is subjected to extreme shocks. The damping characteristics
of this invention may be made adjustable so as to be suitable for
any vehicle, regardless of the conditions under which it
operates.
Yet another object of the invention is to produce a variable
damping system having maintenance free components so as to minimize
damage to the damping system and so as to minimize the routine
maintenance required. Unless there is an equipment failure, no
replenishment of fluids nor exchange of parts in the system is
required.
Still another object of the invention is to produce a variable
damping system which is operable from existing hydraulic or
pneumatic systems in a vehicle having such internal systems. This
invention may be operated from these internal systems, though its
use is not restricted to vehicles having such internal systems.
In one broad aspect, the invention is a variable damping device for
use in hydraulically cushioning a vehicle occupant comprising: a
vehicle frame; an occupant support vertically movable with respect
to said vehicle frame; a first hydraulic cylinder interposed
between said vehicle frame and said occupant support; a closable
valve connected by a fluid transfer line to said first hydraulic
cylinder; a pressurized hydraulic fluid reservoir connected to said
closable valve, thereby providing a passageway closable by said
closable valve between said first hydraulic cylinder and said
hydraulic fluid reservoir; a flow regulating link operably
connected to said closable valve and operable by movements of said
occupant support, whereby said link moves and operates said
closable valve when said occupant support moves in at least one
direction; a second hydraulic cylinder interposed between said flow
regulating link and either said occupant support or said vehicle
frame; a hydraulic fluid line leading from said second hydraulic
cylinder; a constrictive valve connected to said hydraulic fluid
line; a check valve connected to said hydraulic fluid line in
parallel with said constrictive valve, whereby said check valve
allows hydraulic fluid to flow in one direction with respect to
said hydraulic cylinder; and a pressurized hydraulic fluid
reservoir connected to said constrictive valve and to said check
valve.
In another broad aspect, this invention is a variable damping
device for use in hydraulically cushioning a vehicle occupant
comprising: a vehicle frame; an occupant support vertically movable
with respect to said vehicle frame; a hydraulic cylinder interposed
between said vehicle frame and said occupant support; a valve
housing containing a passageway therethrough and a blocking valve
located in said passageway and connected to said hydraulic cylinder
by a fluid transfer line; a pressurized hydraulic fluid reservoir
in communication with said passageway; a barrier panel with respect
to which said valve housing is relatively movable, and said barrier
panel is located in said hydraulic fluid reservoir transverse to
the direction of relative motion of said valve housing, whereby
relative movement of said valve housing causes movement of said
hydraulic fluid in said hydraulic fluid reservoir and said barrier
panel restricts the movement of said hydraulic fluid; a check valve
that spans said barrier panel and allows easy passage of hydraulic
fluid in one direction while opposing passage of the hydraulic
fluid in the opposite direction; and flow regulating linkage
connected to said occupant support and operably connected with a
relatively large minimum clearance to said valve housing, whereby
movement of said occupant support operates said blocking valve only
after said linkage moves beyond the limit of said minimum
clearance.
In one form of the invention, the damping characteristics, in
addition to being variable, may also be adjustable. Adjustment of
the damping characteristics may be made in a number of ways, but is
most easily accomplished where the closable valve is adjustable or
where the constrictive valve is adjustable in those forms of the
invention employing closable or constrictive valves. In those forms
of the invention in which an actuating arm and a flow regulating
link are employed in lieu of a flow regulating linkage connected to
a valve housing, the position in the cycle of oscillation at which
the damping characteristics begin to vary may be changed or
adjusted by varying the manner in which movements of the occupant
support operate the flow regulating link. In one construction, an
actuating arm is attached to the occupant support and is engageable
with the flow regulating link, whereby the actuating arm engages
the link and causes the link to move when the occupant support
moves in at least one direction. The flow regulating link and the
actuating arm may be engaged throughout the oscillation of the
occupant support, in which case damping is continuously varied.
Alternatively, the actuating arm may be constructed so as to engage
a flow regulating link when the occupant support reaches a
predetermined point in either the upper or lower portion of an
oscillatory cycle of the occupant support with respect to the
vehicle frame. In another arrangement, one portion of the flow
regulating link may be biased toward the occupant support. When
contact is established between that portion of the flow regulating
link and the occupant support, the continued movement of the
occupant support in its oscillatory cycle will cause the flow
regulating link to operate the closable valve. Whether or not
continuous operation of the closable valve exists depends upon
whether or not the biased portion of the flow regulating link
establishes continuous contact with the occupant support or whether
contact is established only during a portion of the oscillatory
cycle.
In those forms of the invention employing a flow regulating linkage
connected with a relatively large minimum clearance to a valve
housing, the position in the cycle of oscillation at which the
damping characteristics begin to vary may be changed or adjusted by
varying the minimum clearance provided between the flow regulating
linkage and the valve housing.
The features of several embodiments of this invention are more
clearly illustrated in the accompanying drawings in which:
FIG. 1 is a front elevational view in partial section of an
embodiment of this invention employed with a vehicle seat.
FIG. 2 is a side elevational view of isolated components taken
along the lines 2--2 of FIG. 1.
FIG. 3 is a side elevational view of a modification of some of the
components of FIG. 1.
FIG. 4 is a partial elevational view of a modification of FIG.
1.
FIG. 5 is a front elevational view in partial section of another
embodiment of this invention employed with a supported vehicle
cab.
FIG. 6 is a sectional view taken along the lines 6--6 of FIG.
5.
FIG. 7 is a sectional view taken along the lines 7--7 of FIG.
5.
FIG. 8 illustrates an alternative embodiment of the flow regulating
linkage and valve housing of FIG. 5.
FIG. 9 illustrates an alternative embodiment of the flow regulating
linkage and valve housing of FIG. 5.
FIG. 10 is a sectional view taken along the lines 10--10 of FIG.
9.
FIG. 11 is another alternative embodiment of the flow regulating
linkage and the valve housing of FIG. 5.
Referring now to FIG. 1 there is shown a seat 4 having a seat pan 6
which supports a seat cushion 5. Seat 4 serves as an occupant
support which is vertically movable with respect to vehicle frame
2. Welded to vehicle frame 2 are support angles 3 which extend
upward toward seat 4. At the forward, or highest portions of
support angles 3 are welded lateral U-shaped brackets 37. Sloping
downward from front to rear and welded to support angles 3 are
guide or track sections 10. Extending downward from seat pan 6 are
seat support brackets 7. Seat support brackets 7 extend fore and
aft along seat pan 6 and increase in height from the front to the
rear of the seat. As a result, the extreme downward extremities of
seat support brackets 7 are at the rear of the seat while the
shortest vertical dimensions are at the front of the seat. This is
just opposite the construction of support angles 3. Welded to seat
support brackets 7 are guide or track sections 11, which slope
downward from front to rear at a slope less extreme than that of
track sections 10.
The type of seat suspension depicted in FIG. 1 is a form of a
scissors suspension, which is quite common in the field of vehicle
seating. The scissors arms on each side of the vehicle seat include
an arm 8 sharply pitched downward and to the rear, and an arm 9
pitched downward and to the rear but at a less extreme slope than
arm 8. The front (upper) ends of arms 8 are pivotally fastened to
seat support brackets 7. To the lower ends of arms 8 are pivotally
attached rollers which travel within the confines of track sections
10. Similarly, the upper ends of arms 9 are pivotally attached to
U-shaped brackets 37 while rollers pivotally attached to the lower
ends of arms 9 travel within the confines of track sections 11. The
upper arm 8 and the lower arm 9 on each side of the seat are
pivotally fastened together near their midsections by bolt means
45.
As the vehicle travels over a surface, the seat occupant is
insulated from jolts and vibrations by the damping device of this
invention. To cushion the seat occupant, the seat 4 undergoes
periodic oscillation with respect to vehicle frame 2. As the seat 4
approaches vehicle frame 2 in the downward portion of its cycle of
oscillation, the slope difference between arms 8 and 9 decreases as
the arms 8 and 9 pivot with respect to each other about bolt means
45. The rollers attached to the ends of the arms travel downward
and to the rear in their respective track sections. As seat 4
begins moving upward with respect to vehicle frame 2, the slope
difference of arms 8 and 9 increases as the arms pivot with respect
to each other about bolt means 45 and the rollers attached to the
lower ends of arms 8 and 9 move upward and to the front in their
respective track sections. At the extreme upper position of the
cycle of oscillation, the direction of relative rotation of the
arms 8 and 9 with respect to each other again changes, and the
oscillation cycle repeats itself continuously at a diminished
amplitude in response to a given jolt or vibration.
The damping device of this invention serves to diminish the
amplitude of oscillation rapidly yet cushion the seat occupant
sufficiently during the travel of the vehicle. The spring and
damping device of this embodiment, in addition to vehicle frame 2
and seat 4, includes a first hydraulic cylinder 12, a closable
valve 14, a pressurized hydraulic fluid reservoir 18, a flow
regulating link 29, and actuating arm 24, a second hydraulic
cylinder 31, a hydraulic fluid line 32, a constrictive valve 34, a
check valve 33, and a second pressurized hydraulic fluid reservoir
36. The first hydraulic cylinder 12 is interposed between vehicle
frame 2 and seat 4. The piston arm of hydraulic cylinder 12 is
attached to the underside of seat pan 6 while the cylinder portion
of hydraulic cylinder 12 is attached by brackets to the vehicle
frame 2. Closable valve 14 is connected to hydraulic cylinder 12 by
a fluid transfer line 13. The closable valve 14 is shown in partial
section in FIG. 1 and is comprised of a cylinder member 15 having
an interior radial port 46 and a second port 47. Port 47 could be a
second radial port if it were to emerge from beyond sleeve member
20, but in the construction of the embodiment of FIG. 1 port 47 is
illustrated as being an axial port connected to radial port 46 by a
passageway 61. Closable valve 14 is additionally comprised of a
sleeve member 20 having a radial port 17 alignable with the
interior radial port 46 of cylinder member 15. Sleeve member 20 is
rigidly attached to flow regulating link 29 and cylinder member 15
is rotatably movable about sleeve member 20, although the reverse
construction could alternatively be used. As can be seen in FIG. 1,
cylinder member 15 passes behind the left-hand support angle 3,
which slopes sharply downward and to the rear, and in front of the
left-hand support angle 7 and the left-hand scissors arms 8 and 9.
Within sleeve member 20 just beyond the face of cylinder member 15
is attached an annular ring 48. Annular ring 48 provides an
obstruction for the rigid end 49 of inflatable bag 19, so that
neither rigid end 49, nor any other part of bag 19, can extend
beyond the annular ring 48 toward cylinder member 15. Bag 19 is an
inflatable bag attached to the walls of sleeve member 20 at the end
of sleeve member 20 opposite rigid end 49. A pneumatic line 22 is
connected from this other end of sleeve member 20 to a vessel 23
containing compressed nitrogen. Gas may be added to or withdrawn
from vessel 23 by way of valve 62. By virtue of the attachment of
bag 19 to the interior walls of sleeve member 20, the hollow
portion of sleeve member 20 is divided into a pneumatic cavity 21
and a pressurized hydraulic fluid reservoir 18. As the hydraulic
fluid pressure in reservoir 18 varies, the bag 19 will expand or
contract to equalize the relative pressures between cavity 21 and
reservoir 18 by varying the combined volume of vessel 23, line 22,
and pneumatic cavity 21. A fluid passageway exists between
hydraulic cylinder 12 and hydraulic fluid reservoir 18 by virtue of
the connection formed between fluid transfer line 13 and the ports
in cylinder member 15. This passageway is closable by the closable
valve 14. That is, fluid will not flow between reservoir 18 and
hydraulic cylinder 12 unless the ports 46 and 17 of the closable
valve 14 are aligned. In addition, flow between reservoir 18 and
hydraulic cylinder 12 will exist, but at a restricted rate when the
ports 46 and 17 are only partially aligned.
Since cylinder member 15 is welded to the inside surface of flow
regulating link 29, flow regulating link 29 is operably connected
to closable valve 14. An actuating arm 24 is attached to the seat 4
and is engageable with flow regulating link 29. As can be seen in
FIGS. 1 and 2, actuating arm 24 is threaded at its upper end and is
fastened by means of fasteners 25 and 26 to the left-hand support
angle 7, which extends downward from seat pan 6. Fasteners 25 and
26 are attached in a conventional manner so as to allow the upper
end of the left-hand arm 8 to pivot freely about the lateral
portion of actuating arm 24, while actuating arm 24 is rigidly
attached to support angle 7.
A second hydraulic cylinder 31 is attached to the vehicle frame 2
and is interposed between the flow regulating link 29 and vehicle
frame 2. The piston arm 30 of hydraulic cylinder 31 is pivotally
attached to flow regulating link 29 by means of a knob 39. The neck
of the knob 39 slides freely within the slot 40 so that the piston
rod 30 does not bind as the flow regulating link 29 changes
position. The actuating arm 24 has a series of holes 38 drilled in
its lower end. The lower end of actuating arm 24 is laterally
offset from flow regulating link 29 so that actuating arm 24 is
engageable with flow regulating link 29 only at the hole 38 through
which an engaging bolt assembly 28 extends. A hydraulic fluid line
32 leads from the second hydraulic cylinder 31 to two parallel
valves. One of the valves is a constrictive or throttling valve 34
connected to the hydraulic line 32. Connected in parallel with
constrictive valve 34 is a check valve 33. Check valve 33 allows
hydraulic fluid to flow in one direction with respect to hydraulic
cylinder 31, and in the embodiment of FIG. 1 check valve 33 allows
hydraulic fluid to flow away from hydraulic cylinder 31, but not
toward hydraulic cylinder 31. A pressurized hydraulic fluid
reservoir 36 is connected to the other ends of the valves 33 and 34
by means of a hydraulic fluid line 35.
The advantages of the invention can best be examined by observing
the function of this embodiment throughout a cycle of oscillation.
As the vehicle in which this invention is used travels, jolts are
incurred by vehicle frame 2 and are transmitted toward the seat
occupant in seat 4. The seat occupant is cushioned from these jolts
and vibrations by the spring and the damping device of this
invention. In the case of an extremely hard jolt of vehicle frame
2, the seat 4 moves downward a relatively large distance with
respect to vehicle frame 2. This causes the piston to move downward
within hydraulic cylinder 12, thereby forcing hydraulic fluid
through fluid transfer line 13 and through ports 17, 46, and 47 of
closable valve 14. The hydraulic fluid is forced into reservoir 18,
thereby collapsing bag 19.
As the seat 4 continues in its downward path, the upper ends of the
scissor arms 8 swing downward and forward so that engaging arm 24
engages flow regulating link 29 along the rear surface 50 of flow
regulating link 29 at engaging bolt assembly 28, as depicted in
FIG. 2. Since sleeve member 20 of closable valve 14 is welded to
the rear edge of the left-hand support angle 3 and is thereby fixed
with respect to the frame 2, and since cylinder member 15 is
rigidly welded to flow regulating link 29, flow regulating link 29
and cylinder 15 rotate about the axis of sleeve member 20. This
rotation is in a clockwise direction as viewed in FIG. 2. It is at
the point in the downward stroke of the cycle of oscillation where
engaging bolt assembly 28 first engages surface 50 of flow
regulating link 29 that the damping characteristics of the seat
assembly begin to vary. If the jolt is severe enough to carry seat
4 downward past that point, it is desirable that the damping
characteristics in the system be increased so as to decrease the
amplitude of oscillation from that which would otherwise occur with
fixed damping. As the cylinder member 15 begins to rotate clockwise
(FIG. 2) with respect to sleeve member 20, the port 46 begins to
rotate out of alignment with port 17 in sleeve member 20. This
restricts the flow of fluid from the first hydraulic cylinder 12 to
the hydraulic fluid reservoir 18 as the seat 4 proceeds in its
downward path of oscillation. Eventually, there is no fluid flow
from hydraulic cylinder 12 to the reservoir 18 due to the closure
of closable valve 14. Because the port 17 rotates out of alignment
with port 46, the damping characteristics of the hydraulic cylinder
12 increase. More simply stated, the damping of hydraulic cylinder
12 increases as the seat 4 moves further downward.
The rotation of flow regulating link 29 causes the piston rod 30 to
move downward within the second hydraulic cylinder 31. The movement
of piston rod 30 begins when actuating arm 24 first engages flow
regulating link 29. The movement of piston rod 30 forces hydraulic
fluid out of hydraulic cylinder 31 into hydraulic fluid line 32 and
through check valve 33 and constrictive valve 34 towards the
pressurized hydraulic fluid reservoir 36. Check valve 33 is
constructed to allow much easier passage of hydraulic fluid toward
the reservoir 36 than is constrictive valve 34. For this reason,
almost all of the fluid flowing out of the second hydraulic
cylinder 31 through fluid line 32 passes through the check valve 33
towards reservoir 36.
When the seat 4 reaches its lowest position and reverses direction
and begins its upward movement during the other half of its cycle
of oscillation, it is desirable that the damping not be reduced
rapidly but rather that it be maintained at an increased level for
a period of time anticipating other severe oscillations which would
otherwise contribute to the discomfort of the vehicle operator. It
is for this reason that check valve 33 is constructed so that no
flow of hydraulic fluid may occur through it from the reservoir 36
to the second hydraulic cylinder 31. Instead, all hydraulic fluid
flowing from reservoir 36 to hydraulic cylinder 31 must pass at a
relatively slow rate through the constrictive valve 34 and the
ascension of piston rod 30 is thus controlled. This allows the flow
regulating link 29 to slowly and smoothly rotate counterclockwise
(FIG. 2) and thus maintain increased damping for a time as
determined by the flow through constrictive valve 34. As flow
regulating link 29 rotates counterclockwise, the ports 46 and 17 of
closable valve 14 begin to again come into alignment. As the
alignment of these ports becomes more perfect, damping decreases
and the suspension system regains the original damping
characteristic appropriate for a ride over a relatively smooth
surface. Because of the controlled delay in the rotation of flow
regulating link 29, as the seat 4 continues to ascend, the
actuating arm 24 loses contact with the rear surface 50 of flow
regulating link 29. The actuating arm 24 does not reengage flow
regulating link 29 until after the seat 4 reaches its extreme upper
position in its path of oscillation and again undergoes downward
movement to below the midpoint of its path of oscillation. If the
vibrations to which the vehicle occupant is subjected are small
enough, the amplitude of the cycle of oscillation will be small
enough so that actuating arm 24 will not engage flow regulating
link 29 unless a more severe jolt is encountered. As governed by
the weight of the operator and the roughness of the ride likely to
be encountered, the constrictive valve 34, the engaging bolt
assembly 28, the gas pressure within vessel 23, and the hydraulic
fluid pressure within reservoir 36 may be appropriately adjusted in
order to optimize the damping characteristics of the system.
Referring now to FIG. 2, it can be seen that for less damping
control it is wise to place engaging bolt assembly 28 through one
of the upper holes 38 in actuating arm 24, since this will change
the ratio of rotation of flow regulating link 29 to the motion of
actuating arm 24. To change the rate of return of the seat to the
ride position after extreme jolts, the orifice of the constrictive
valve may be varied or the pressure within the hydraulic fluid
reservoir 36 may be adjusted.
While the actuating arm 24 of this embodiment has been shown to
engage the flow regulating link 29 when the occupant support is in
the lower portion of the path of oscillation of the seat 4 with
respect to the vehicle frame 2, the engagement of the actuating arm
with the flow regulating link could be made to occur in the upper
portion of the path of oscillation in order to accomplish the same
purpose.
FIG. 3 illustrates an alternative embodiment of the actuating arm,
the closable valve, and the second hydraulic cylinder of this
invention.
FIG. 3 is a front elevational view of these components isolated
from the remaining portion of the embodiment of FIG. 1. The
modification of FIG. 3 works identically to that of FIGS. 1 and 2
with the following exceptions. The actuating arm 111 is not curved
but is merely a fastening means and passes directly through the
flow regulating link 29'. In FIG. 3, flow regulating link 29' does
not rotate during the downward movement of the occupant support,
but rather undergoes only translational motion. That is, as the
occupant support moves downward, actuating arm 111 forces flow
regulating link 29' downward. Closable valve 14' is a needle valve
comprised of a needle member connected by a shaft to the end 43 of
connecting lever 42, and an orifice member in a housing 113 rigidly
connected to support angle 112. Support angle 112 is rigidly
connected to vehicle frame 2. During the downward movement of the
occupant support in the lower portion of the oscillatory cycle, the
flow regulating link 29' forces connecting joint 41 to pull
downward on end 44 of lever 42. Lever 42 passes through an aperture
in support angle 112 and is pivoted at its point of contact with
angle 112. As connecting joint 41 pulls downward on end 44 of lever
42, end 43 of lever 42 is pulled upward thereby pulling the needle
valve of this embodiment into the orifice of the closable valve
14'. The resulting effect is the same as occurred with the
rotational valve of FIGS. 1 and 2. As in the embodiment of FIGS. 1
and 2, hydraulic fluid is forced through a check valve and
constrictive valve (not shown) from a second hydraulic cylinder
31'. In the embodiment of FIG. 3, there is no rotational motion of
flow regulating link 29'.
FIG. 4 illustrates another variation of this invention. FIG. 4 is
an isolated front view of a portion of a seat 16 vertically movable
with respect to vehicle frame 64. The operation and manner of
connection of the scissors arms of FIG. 4 is identical to that of
FIG. 1. In addition, the closable valve 54 is identical to the
closable valve 14. All components of the embodiment of FIG. 4 not
illustrated are identical to corresponding members of FIG. 1. The
flow regulating link 51, however, differs in construction from flow
regulating link 29 in FIG. 1. Flow regulating link 51 is comprised
of a main central disk portion 67 to which is welded the cylinder
member 114 of closable valve 54. Sloping forward and upward at an
angle from disk portion 67 there extends a seat engaging portion 60
of flow regulating link 51. This seat engaging portion 60 is biased
toward seat 16 by a biasing spring 116. Portion 60 of the flow
regulating link 51 is in contact with seat pan 52 during at least a
part of the cycle of oscillation. As seat 16 moves downward toward
vehicle frame 64 during the cycle of oscillation, portion 60 of the
flow regulating link 51 is forced forward and downward, thereby
rotating the entire flow regulating link 51. This rotation causes
closable valve 54 to operate in the same manner as did valve 14 of
FIG. 1. As flow regulating link 51 rotates, a connection link 115,
attached to the disk portion 67 of flow regulating valve 51, pulls
downward on piston rod 56 of second hydraulic cylinder 55.
Hydraulic cylinder 55 is attached to the underside of seat pan 52
of seat 16. Since portion 60 of flow regulating link 51 is in
contact with seat pan 52 and is operated by seat pan 52 during the
downward portion of the cycle of operation, piston rod 56 moves
downward relative to seat 16 and causes hydraulic fluid to be drawn
into second hydraulic cylinder 55 as seat 16 moves downward.
Hydraulic fluid is drawn from a reservoir through a hydraulic fluid
line 57 in which are positioned a constrictive valve 59 and a check
valve 58. The positioning of check valve 58 to allow flow into
second hydraulic cylinder 55 makes the operation of the damping
system correspond to the operation of the embodiment of FIG. 1.
Check valve 58 could be positioned so as to allow flow in the
opposite direction, in which case the heavy damping would occur
during the downward stroke of the cycle of oscillation, rather than
the upward stroke as happens in the damping systems of FIGS. 1 and
4. The effect on the seat occupant would be the same.
Referring now to FIG. 5, there is shown an alternative embodiment
of this invention. A vehicle cab 95 is vertically movable with
respect to a vehicle frame 2' as governed by a suspension system
very similar to that of FIG. 1. The elements of the scissors
suspension of FIG. 5 include arms 8' and 9', cab support brackets
7', track sections 10' and 11', support angles 3', lateral U-shaped
brackets 37', and bolt means 45'. These elements cooperate and
perform the same function as do their unprimed equivalents in FIG.
1 except that the pivot points are selected to provide parallel
motion. In addition, the embodiment of FIG. 5 is also similar to
that of FIG. 1 in that a hydraulic cylinder 12 is interposed
between the vehicle frame 2' and the vehicle cab 95.
The spring and damping means of this embodiment of the invention,
in addition to the vehicle frame 2', the vehicle cab 95, and the
hydraulic cylinder 12, includes a valve housing 68, a pressurized
hydraulic fluid reservoir 101, a barrier panel 72, a check valve
71, and flow regulating linkage that is operably connected to the
valve housing 68. The valve housing 68 is connected to hydraulic
cylinder 12 by a fluid transfer line 13'. Valve housing 68 is shown
in partial section in FIG. 5 and contains a passageway 69 extending
therethrough and a blocking valve located in the passageway 69 and
connected to the hydraulic cylinder 12 by fluid transfer line 13'.
The blocking valve of this embodiment may be considered to be the
interface between the port 100 located at the end of passageway 69
in valve housing 68, and the aperture 65 where the fluid transfer
line 13' communicates with the interior of a cylindrical sleeve
member 66 welded to the left-hand support angle 3'. Relative
rotation of the valve housing 68 with respect to sleeve member 66
causes the port 100 and the aperture 65 to come into alignment or
to shift from an aligned position. When the port 100 and the
aperture 65 are aligned, hydraulic fluid may flow freely from the
hydraulic cylinder 12 to the hydraulic fluid reservoir 101. When
the valve housing 68 shifts with respect to the sleeve member 66,
thereby moving the port 100 and the aperture 65 out of alignment,
no fluid may flow through the port 100 or the aperture 65 because
valve housing 68 fits closely within sleeve member 66 thereby
sealing the port 100 and the aperture 65. At the other end of
passageway 69 in valve housing 68 is located a port 106 in
communication with hydraulic fluid reservoir 101.
Within sleeve member 66 just beyond valve housing 68 there is
located a transverse separation panel 70 with a passageway 74
therethrough. Transverse separation panel 70 is constructed in the
form of an annular ring perforated by an offcenter passageway 74
that provides an obstruction for the rigid end 107 of inflatable
bag 19', so that neither rigid end 107, nor any other part of bag
19', can extend beyond the transverse separation panel 70 toward
valve housing 68. Bag 19' is an inflatable bag attached to the
walls of sleeve member 66 to the right of rigid end 107. By virtue
of the attachment of bag 19' to the interior walls of sleeve member
66, the portion of sleeve member 66 to the right of valve housing
68 is divided into a pneumatic cavity 75 and pressurized hydraulic
fluid reservoir 101. As the hydraulic fluid pressure in reservoir
101 varies, bag 19' will expand or contract to equalize the
relative pressures between cavity 75 and reservoir 101 by varying
the volume of the pneumatic cavity 75. Air or other gas may be
added to or withdrawn from the pneumatic cavity 75 through a
pneumatic valve 76.
The valve housing 68 has a cylindrical central portion 110 and two
end portions. One of the end portions, end portion 108, is of a
segmental cross section slightly only smaller than a semicircle
having the same common radius. The cross section of end portion 108
is best illustrated in FIG. 7.
The barrier panel 72 is located in the hydraulic fluid reservoir
101 transverse to the direction of relative motion of the valve
housing 68. Barrier panel 72 is a planar rectangle radially
extending from the axis of the sleeve member 66 to the inner
surface of the sleeve member 66 coextensive with and positioned
generally opposite the first segmental end portion 108 of valve
housing 68 and intersecting and welded to transverse separation
panel 70 within the sleeve member 66. Due to the geometry of the
end portion 108 and the barrier panel 72, it can be seen that the
valve housing 68 is relatively movable with respect to the barrier
panel 72, and that relative movement of the valve housing 68 causes
movement of the hydraulic fluid in the hydraulic fluid reservoir
101. It can also be seen that the barrier panel 72 restricts the
movement of this hydraulic fluid. It can be seen from FIG. 7 that
when the valve housing 68 (including the end portion 108) rotates
counterclockwise, hydraulic fluid is forced from the lower
left-hand portion of the fluid reservoir 101 to the lower
right-hand portion of the fluid reservoir 101. The only path
available through which the hydraulic fluid can flow is through the
channel between the end portion 108 and the barrier panel 72. This
channel is centrally located with respect to the sleeve member 66.
The hydraulic fluid cannot flow around the barrier panel 72 because
one end of barrier panel 72 abuts and is welded to the transverse
separation panel 70 while the other end of barrier panel 72
terminates very close to the central portion 110 of valve housing
68. A rubber gasket or other seal may be used at this junction.
Similarly, the face of end portion 108 is also located immediately
adjacent the transverse separation panel 70. The viscosity of the
hydraulic fluid as it moves through the channel between the end
portion 108 and the barrier panel 72 causes a great deal of
resistance to the counterclockwise rotation of the valve housing
68. The same is not true, however, when the valve housing 68
rotates clockwise. This is because a check valve 71 is located in
the barrier panel 72 and allows easy passage of the hydraulic fluid
from the right-hand side of the panel to the left-hand side of the
panel while opposing passage of the hydraulic fluid from the
left-hand side of the panel to the right-hand side of the panel.
While the check valve 71 could be located in an external line
entering and leaving the sleeve member 66, it is more conveniently
located in an opening 79 extending transversely through the barrier
panel 72.
The other or second end portion of 109 of the valve housing 68 is
also of a segmental cross section only slightly smaller than a
semicircle having the same radius. The outer boundaries of the
cross section of end portion 109 is, but need not be, identical to
the outer boundaries of the cross section of end portion 108, and
is so illustrated in FIG. 6. The flow regulating linkage is
comprised of an actuating arm 24' threaded at its upper end and
fastened by means of fasteners 25' and 26' to the left-hand cab
support angle 7', which extends downward from cab 95. The fasteners
25' and 26' rigidly fasten the lateral portion of the actuating arm
24' to the cab support angle 7'. The lower end of the actuating arm
24' is pivotally fastened to a torsion arm 117 by a pivot pin
assembly 118. The torsion arm 117 is rigidly fastened to an
engaging cylinder 119 which extends axially into the sleeve member
66. The engaging cylinder 119 has an end 80 adjacent to the end
portion 109 of the valve housing 68. Adjacent end 80 is of
segmental cross section only slightly smaller than a semicircle
having the same radius and is located in sleeve member 66 generally
opposite the second end portion 109 of valve housing 68, as
indicated in FIG. 6. The flow regulating linkage is thereby
connected to the occupant support (vehicle cab 95) and is operably
connected with a relatively large minimum clearance to the valve
housing 68. The minimum clearance is formed by the distance between
the upper surface 77 of adjacent end 80 of the actuating cylinder
119 and the lower surface 78 of the end portion 109 of the valve
housing 68. It can be seen that valve housing 68 will be rotated
only after adjacent end 80 is rotated moves beyond the limits of
the relatively large minimum clearance and after the edge of
surface 77 makes contact with the edge of surface 78.
The minimum between the flow the regulating linkage and the valve
housing 68 may take a number of different forms. One such variation
is illustrated in FIG. 8 in which the second end portion of a valve
housing 85 and an adjacent end 83 of the flow regulating linkage
are axially aligned within the sleeve member 66 and are connected
by an axially extending torsion bar 87. A rotation of the adjacent
end 83 of the flow regulating linkage will have no effect on the
valve housing 85 until enough torsion is applied to torsion bar 87
to overcome the friction of valve housing 85 with respect to sleeve
member 66. When this torsional force is reached, the valve housing
85 will begin to rotate port 81 with respect to the fluid transfer
line 13'. The same result is achieved in the modification of FIG.
9. In FIG. 9 the second end portion of the valve housing 86 has a
circular surface and an adjacent end 84 of the flow regulating
linkage is coaxial with the valve housing 86 and has a circular
surface. One of the aforesaid circular surfaces, in this case the
surface of the end portion of the valve housing 86, has at least
one and preferably two tracks extending in arcs about the axis of
the valve housing 86. These tracks take the form of grooves that
are shallow at one end and deep at the other end in the circular
surface of valve housing 86. The deep ends 91 and 92 of the grooves
are each located at the clockwise extremities of the grooves as
depicted in FIG. 10. The deep ends 91 and 92 of the grooves are
abruptly terminated by an obstacle, which in the embodiment
illustrated is merely comprised of the structural material of the
valve housing 86. The shallow ends 93 and 94 of the grooves
smoothly blend into the circular surface of the second end portion
of the valve housing 86. Guide followers 88 protrude from the other
circular face, the circular surface of the adjacent end 84 of the
flow regulating linkage. These guide followers are axially movable
within the longitudinal wells 90 and are biased toward the circular
surface of the end portion of the valve housing 86 by springs 89.
The guide followers 88 engage the grooves in the face of the end
portion of the valve housing 86 so that relative rotation of the
end 84 of the flow regulating linkage with respect to the valve
housing 86 creates an operable connection between the flow
regulating linkage and the blocking valve only when the rotation of
the guide followers is resisted by the structural material of the
valve housing 86 at the deep ends 91 and 92 of the grooves. The
arcuate travel of the guide followers within the grooves provides
the minimum clearance before engagement of valve housing 86 and
adjacent end 84 of the flow regulating linkage in this modification
of the invention.
The minimum clearance is provided in yet another form in the
modification of FIG. 11. In this modification the second end
portion of the valve housing 102 and an adjacent end 103 of the
flow regulating linkage are axially aligned within the sleeve
member 66. The second end of the valve housing 102 terminates in an
elliptical face 105. Similarly, the adjacent end 103 of the flow
regulating linkage terminates in an elliptical face 104. Elliptical
faces 104 and 105 are parallel and separated slightly from each
other, the slight separation creating the minimum clearance. That
is, the end 103 of the flow regulating linkage must rotate a slight
distance before contact is established with the valve housing 102.
It is only after this initial contact is made that the port 82 is
rotated with respect to the fluid transfer line 13'.
Returning to the embodiment of FIG. 5, it can be seen that the
operation of the embodiment of FIG. 5 is very similar to that of
FIG. 1. At the beginning of a cycle of oscillation, the blocking
valve is open as the port 100 and the aperture 65 are fully
aligned. As the cab 95 moves downward in the downward portion of
the cycle of oscillation, the actuating arm 24' rotates the torsion
arm 117 thereby rotating the actuating cylinder 119. This rotation
has no effect on the valve housing until the edges of the surfaces
77 and 78 contact each other. When this contact is established, the
valve housing 68 begins to rotate and the port 100 begins to move
out of alignment with port 65. Prior to the contact of surfaces 77
and 78, fluid is easily forced through the fluid transfer line 13',
through the blocking valve, and through the passageway 69 into the
hydraulic fluid reservoir 101. The damping characteristics of the
system during this early portion of the cycle of oscillation are
quite small since the path and flow of the hydraulic fluid offers
little resistance. As the cab 95 continues to move downward,
however, and as the port 100 begins to move out of alignment with
the port 65, the fluid flow from the hydraulic cylinder 12 to the
hydraulic fluid reservoir 101 diminishes thereby increasing the
damping characteristics of the system. The rotation of the valve
housing 68 is not resisted by the viscosity of the fluid in the
hydraulic fluid reservoir 101 because the fluid readily passes
through the check valve 71 in the barrier panel 72 as the valve
housing 68 rotates clockwise. At the lowest position of the vehicle
cab 95, the blocking valve is completely closed. As the vehicle cab
95 begins to rise, the damping characteristics of the system are
increased by the resistance of the hydraulic fluid within the
hydraulic fluid reservoir 101. That is, the counterclockwise
rotation of valve housing 68 by the flow regulating linkage is
resisted by the viscosity of the hydraulic fluid within the
hydraulic fluid reservoir 101. As the valve housing 68 attempts to
rotate counterclockwise, the check valve 71 opposes flow through
the opening 79, thereby limiting the allowable path of flow to the
channel formed between the surface of the first end 108 and the
barrier panel 72. Because this channel is so narrow, the cab is
allowed to rise only at a rather slow rate even after the port 100
comes into alignment with the port 65 and fluid may freely flow
from the hydraulic fluid reservoir 101 into the hydraulic cylinder
12. The resulting increased damping characteristics of the system
exist until the cab 95 reaches its uppermost position in the cycle
of oscillation. The retention of these high damping characteristics
for a time is desirable because of the likelihood of further
extreme jolts such as that which caused the original cycle of
oscillation in the first place.
During the smooth ride condition, the actuating cylinder 119
oscillates in rotation only slightly within the sleeve member 66.
This slight oscillation is normally within the minimum clearance
allowed by the system so that the damping characteristics are not
changed during the level ride condition, but only increase when the
vehicle is subjected to extreme shocks or vibrations.
As will be obvious to those skilled in the field of vehicle
occupant seating, numerous mechanical equivalents may be provided
in place of those specifically enumerated in the embodiments of
this invention. For this reason, the foregoing description and
illustrations of the mechanical components of this invention are
for purposes of illustration only, as the interaction of these
components in the manner claimed is considered to be the invention
disclosed herein.
* * * * *