U.S. patent number 3,717,104 [Application Number 05/053,050] was granted by the patent office on 1973-02-20 for active roll controling truck stabilizing mechanism.
This patent grant is currently assigned to United Aircraft Corporation. Invention is credited to James William Clark, Ernest Harry Law.
United States Patent |
3,717,104 |
Law , et al. |
February 20, 1973 |
ACTIVE ROLL CONTROLING TRUCK STABILIZING MECHANISM
Abstract
A stabilizing railway vehicle suspension apparatus incorporates
swing arms, actuators, springs and a control system so disposed as
to automatically impart both rolling and lateral transverse motions
to the car body when operating on curved track. The swing arms are
mounted on the truck bolster and are directed upwardly and
outwardly to their pivotal mountings on the roll platform upon
which the car body is suspended by springs. Upon signal from an
accelerometer mounted on the roll platform or truck the control
system actuates the mechanism so as to roll and translate the car
body in a manner that provides improved passenger comfort and
improved stability against overturning.
Inventors: |
Law; Ernest Harry (Marlborough,
CT), Clark; James William (Glastonbury, CT) |
Assignee: |
United Aircraft Corporation
(East Hartford, CT)
|
Family
ID: |
21981604 |
Appl.
No.: |
05/053,050 |
Filed: |
July 8, 1970 |
Current U.S.
Class: |
105/164; 105/171;
105/210; 105/199.2 |
Current CPC
Class: |
B61F
5/22 (20130101) |
Current International
Class: |
B61F
5/02 (20060101); B61F 5/22 (20060101); B61f
003/08 (); B61f 005/24 (); B61f 005/40 () |
Field of
Search: |
;105/3,4R,157R,164,171,182R,185,19R,191,197R,197B,210,199A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Forlenza; Gerald M.
Assistant Examiner: Beltran; Howard
Claims
We claim:
1. A railway vehicle suspension apparatus comprising a truck having
a lower frame which supports the wheel sets, an upper frame mounted
on said lower frame for pivotal movement, a roll platform above
said truck on which a car body is mounted, roll control mechanism
between said upper frame and said platform for forcibly imparting
both rolling and inward transverse motions to said car body when
traversing a curved section of track above the design speed for
said track, said mechanism including rigid left- and right-hand
swing arms having pivoted connections at their lower ends with said
upper frame and extended upwardly and outwardly and having pivoted
connections at their upper ends with said platform, actuating means
for imparting said motions to said car body as controlled by said
swing arms, and an accelerometer mounted on a part of the vehicle
which is affected by lateral accelerations as said vehicle enters
and leaves said curved section of track for controlling said
actuating means.
2. A railway vehicle suspension apparatus comprising a truck
adapted to run on parallel rails and having a lower frame which
supports the wheel axles, wheels at the ends of said axles, a
bolster pivotally mounted on said frame, a roll platform above said
bolster which supports a car body, means for improving the
stability of the vehicle against overturning by maintaining the
line of action of the resultant of the weight and centrifugal force
vectors between and well away from said rails when the vehicle is
negotiating a curve including rigid left- and right-hand swing arms
pivotally connected at their lower ends with said bolster and
extended upwardly and outwardly and having their upper ends
pivotally connected to said platform, actuator means for positively
moving said platform as controlled by said swing arms, and control
means including an accelerometer for energizing said actuator means
both to roll said car body about a fore and aft axis and to bodily
translate it laterally inward toward the center of said curve.
3. A railway vehicle suspension apparatus for high speed trains
comprising a vehicle truck having a lower frame which supports the
wheel axles, an upper frame mounted on said lower frame for
movement about a vertical axis, a roll platform, a car body mounted
on said platform, and active control mechanism mounted between said
upper frame and said platform including rigid left-and right-hand
swing arms having pivoted connections at their lower ends with said
upper frame, said swing arms having their upper ends extended
upwardly and outwardly and having pivoted connections at their
upper ends with said platform, springs connecting said upper frame
and said platform, and left-and right-hand actuators for imparting
both rolling and bodily lateral motion to said car body inward
toward the center of curvature of a curved section of track, said
actuators having pivotal connections at their lower and upper ends
with said upper frame and with said platform respectively, an
accelerometer mounted on a part of said vehicle which is affected
by lateral accelerations as said vehicle enters and leaves said
curved section of track, and control means responsive to variations
in accelerometer voltage output for controlling said actuators to
impart said inward motions to said body.
4. The suspension apparatus of claim 3 in which the springs
connecting the upper frame and the platform are tension-compression
springs capable of returning the car body to its initial position
in the event of actuator failure.
5. The suspension apparatus of claim 2 in which the actuators are
hydraulically operated by means of a selector valve.
6. The suspension apparatus of claim 3 in which the actuators are
electrically operated through a reversible electric motor and rack
and pinion mechanism.
7. A railway vehicle suspension apparatus comprising a truck having
a lower frame which supports the wheel sets, an upper frame
pivotally mounted on said lower frame, a roll platform above said
truck on which a car body is mounted, roll control mechanism
between said upper frame and said platform for forcibly imparting
both rolling and inward transverse motions to said car body as the
latter traverses a curved section of track above the design speed
for the track, said mechanism including rigid left-and right-hand
swing arms having pivoted connections at their lower ends with said
upper frame and extended upwardly and outwardly and having pivoted
connections at their upper ends with said platform, actuating means
for imparting said motions to said body as controlled by said arms,
means for energizing said actuators as said vehicle enters or
leaves said curved section of track including an accelerometer
mounted on said truck and a swing-arm potentiometer for modifying
the output signal of said accelerometer which is responsive to
changes in the angle between said swing arms and said platform.
8. A railway vehicle suspension apparatus comprising a truck having
a lower frame which supports the wheel sets, an upper frame
pivotally mounted on said lower frame, a roll platform above said
truck on which a car body is mounted for the transportation of
passengers, left-and right-hand swing arms having pivoted
connections at their lower ends with said upper frame and extended
upwardly and outwardly and having pivoted connections at their
upper ends with said platform, and means between said upper frame
and said platform including rigid left-and right-hand actuators
operative when the vehicle traverses a curved section of track at a
speed higher than the speed for which the curve was designed for
positively translating said car body under control of said swing
arms laterally inward toward the center of curvature of the track
to oppose vehicle overturning while angularly rolling said car body
forcibly against centrifugal forces to eliminate the lateral
component of acceleration acting on the passengers within the
vehicle.
Description
BACKGROUND OF THE INVENTION
In the interest of passenger comfort and also to guard against a
tendency of the car to overturn outwardly when negotiating a curve,
it has been the practice to bank the roadbed to at least partially
eliminate the lateral accelerations acting on the passengers and,
to some degree, to stabilize the car on curves. With the advent of
the turbo-jet-driven trains which operate at much higher speeds a
system of passive, pendulous suspension of the car body has been
used which enables these faster trains to operate on existing road
beds which were banked for trains operating at much lower speeds
without passenger discomfort. In this passive roll control system,
however, inclination of the car body on a curve resulted in greatly
increasing the possibility of overturning the vehicle outwardly if
the curve is traversed too fast or overturning the vehicle inwardly
if the curve is traversed too slowly.
SUMMARY OF THE INVENTION
This invention relates to railway vehicle suspension systems.
Specifically, it relates to improved apparatus for suspending and
controlling the angular and lateral transverse position of a
railway car body during traverse of curved track in such a manner
as to provide good riding qualities for the passengers therein and
also to increase the stability of the railway vehicle with respect
to overturning. Improved riding qualities are obtained by angularly
rolling the car body so as to effectively eliminate the lateral
component of acceleration that would be experienced by the
passengers in the curve. Improved stability is obtained by
translating the car body laterally inward toward the center of
curvature if the curve is traversed at a speed greater than the
speed used in designing the roadbed banking or track
superelevation. Similarly, improved stability is obtained by
translating the car body laterally outward from the center of
curvature if the curve is transversed at a speed below the design
speed for the roadbed or track superelevation. As will be described
herein, these effects are obtained by a combination of linkages
between the axle or truck frame, hydraulic or electromechanical
actuators, and a control system employing one or more
accelerometers.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a cross-sectional schematic view of a railway vehicle
traversing a curve, showing the forces acting upon a pendulously
suspended railway vehicle car body over which the present invention
is an improvement;
FIG. 1B is a similar view showing the forces acting upon a car body
of a vehicle equipped with the positive roll suspension system of
this invention;
FIG. 2 shows an exploded view of a railway truck employing the
improved apparatus of this invention.
FIG. 3 shows a cross-sectional view of the improved apparatus
looking in the fore or aft direction of the railway vehicle;
FIG. 4 shows a cross-sectional view taken on line 4--4 of FIG.
3;
FIGS. 5A and 5B are schematic cross-sectional diagrams illustrating
the operation of the improved apparatus; the electrical and
hydraulic elements shown in FIG. 5A being omitted in FIG. 5B for
purposes of clarity
FIG. 6 is a schematic diagram showing the kinematics of operation
of the improved apparatus including the path of the car body center
of gravity and the path of the instantaneous roll center;
FIG. 7 is a block diagram of the essential elements of a preferred
embodiment of the roll control system employing electro-mechanical
actuator mechanisms;
FIG. 8 is a similar block diagram of the control system for an
alternate embodiment employing hydraulic actuators;
FIG. 9 is a block diagram of a control system in which the sensing
accelerometer would be differently located from the location in
FIGS. 7 and 8.
FIG. 10 is a cross-sectional diagram of an electro-mechanical
actuator;
FIG. 11 is a cross-sectional diagram of an hydraulic actuator;
and
FIG. 12 is a cross-sectional diagram of a selector valve that could
be employed in an hydraulically actuated system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
At the present time, railway vehicles are usually suspended with
respect to their transporting wheels and axles or truck frames by
various suspension linkages employing steel or air bag springs,
swing arms, and sometimes hydraulic shock absorbers or the like.
These prior art arrangements employ the suspension system primarily
to provide a passenger ride which is adequate with respect to
shocks induced by roadbed unevenness, track irregularities,
crossing of switches, etc. Attempt is also made in their design to
alleviate to some degree important ride quality problems arising
from lateral accelerations of the car body produced in curves.
However, such conventional systems do not adequately alleviate
lateral accelerations on the passengers under all conditions.
Moreover, inclination of the car body is accompanied by lateral
translation of the car body in a direction tending to decrease
stability of the railway vehicle, thereby greatly increasing the
possibility of overturning outward if the curve is traversed too
fast or inward if the curve is traversed too slowly. In addition,
this lateral translation, when combined with the lateral
accelerations felt by the passengers, causes apprehension and
discomfort on the part of the passengers.
One prior art technique that has been employed in the attempt to
correct the above mentioned deficiencies is illustrated
schematically in FIG. 1A. This figure shows a passive pendulous
suspension system in which 1 is the surface of the roadbed, 2 are
the rails, 3 is the wheel set, 4 is the axle, and 5 is the outline
of the car body. In this suspension system, the center of gravity 6
of the car body is below the car body pivot axis 7, that is, the
center of gravity is below the center of rotation. The primary
forces acting upon the car body in the curve are shown as the car
body weight 8, the centrifugal force 9, and the resultant 10 of the
weight and the centrifugal force which acts along the car body
centerline through the center of gravity and the center of
rotation. Under the combined influences of the weight and
centrifugal force, the car body rotates about center of rotation 7
through an angle .phi. such that there is no net transverse or
lateral acceleration upon the passengers, that is, there is no
acceleration perpendicular to the car body centerline.
One disadvantage of this prior art system is that it is most
readily applied to car body configurations in which the car bodies
are supported from single-axle wheel sets and frame apparatus
located between cars. This allows a frame to be constructed such
that the center of rotation 7 can be above the center of gravity 6.
This construction is not readily applicable to railway vehicles in
which the car body is suspended from two multiple-axle trucks
beneath the car body. A second very significant disadvantage is
that the roll of the car body causes the resultant force 10 to pass
closer to the outside rail if the train traverses the curve at a
speed higher than the design speed for the roadbed banking.
Conversely, the resultant force 10 passes closer to the inside rail
if the speed is less then the design speed for banking of the
roadbed. The distance a shown in FIG. 1A, which is the distance
between the intersection of the line of action of the resultant
force 10 and the track plane 11a and a line 11b through the center
of rail 2, is therefore an indication of the contribution of the
car body to the stability of the vehicle. If the resultant force
passes outside of the outside rail in FIG. 1A, then the car body
contributes markedly to the tendency for the vehicle to overturn
outward. An analogous situation exists for overturning inward. Thus
the destabilizing influence of the car body rotation in this prior
art method places important restrictions on the range of speeds at
which these vehicles can traverse a given curve. This tendency to
overturn also causes restrictions to be placed on the car body roll
angle .phi. which in turn additionally comprises the range of
operating speeds because of passenger comfort considerations.
FIG. 1B indicates the more desirable inclination and translation of
the car body which occurs with the structure of the present
invention. By the apparatus to be described herein the car body is
forcefully rotated through the same angle .phi. and is also
translated laterally such that the resultant force 10 intersects
the rail plane 11a at 11 in such a manner that the distance a is
increased. This figure shows the operation when the railway vehicle
traverses the curve at a speed above the design speed for roadbed
banking. A similar situation exists when the railway vehicle
traverses a curve at a speed below the design speed for roadbed
banking. The effect is obtained by lowering the location of the
roll center 7. Although points 7 and 11 are shown coinciding in
FIG. 1B, this is not a necessary requirement of the invention. The
locations of points 7 and 11 will be determined by such factors as
the dimensions of the car body, the lengths of the swing arms, to
be described subsequently, allowable translation of the car body to
be consistent with interference restrictions on operating envelopes
on multiple-track curves, etc.
By comparison of FIGS. 1A and 1B it can be seen that the present
invention provides not only improved riding qualities but also a
marked improvement in stability against overturning. This invention
may also be employed for suspension systems between car bodies or,
as described subsequently, may be employed with multiple-axle
trucks beneath car bodies.
An exploded view of the mechanism required for achieving this
combined rolling and lateral translatory car body motion is shown
in FIG. 2. In this figure are shown the lower truck frame 12 upon
which are mounted the wheel sets 3 and axles 4, the truck frame
center plate 13, the pivot pin 14, the bolster, or upper truck
frame 15, the bolster centerplate 16, the pivot pin hole 17 a
plurality of mounting lugs 18, the roll platform 19, the car body
air springs 20, a plurality of mounting lugs 21, swing arms 22, the
left-hand actuator 23, the left-hand springs 24 and accelerometer
25. This figure is intended for illustrative purposes only. The
mechanism may be applied to a single-axle suspension between car
bodies or beneath a car body. When applied to a truck, the truck
may have more than two axles; the car body may be mounted on the
roll platform using a different spring arrangement, or a different
number of springs; and, as discussed subsequently, the
accelerometer may be mounted in a different location. The
symmetrically disposed right-hand actuators, swing arms, and
springs on the opposite side of the truck from that shown in FIG. 2
have been omitted for purposes of clarity.
The truck frame 12 is pivotally mounted with respect to the bolster
15 to allow the truck to yaw about pivot pin 14 in a manner similar
to that of conventional railway trucks. The swing arms 22 and their
opposite counterparts are pivotally mounted to the bolster by means
of pins which extend through lugs 18 and are pivotally mounted to
the roll platform 19 by means of pins through lugs 21. It should be
particularly noted here that these swing arms are rigid links and
are directed outward and upward from the bolster 15 to the roll
platform 19. The outwardly directed swing arms are the key feature
of the present invention in that lateral translational motion of
the roll platform with respect to the bolster 15 is accompanied by
rotation of the roll platform 19 about a longitudinal fore-and-aft
axis. Forceful motion of the roll platform 19 is achieved by
extending and shortening actuators 23 which are also pivotally
mounted to the bolster 15 by means of pins through lugs 18 and to
the roll platform 19 by means of pins through lugs 21. The function
of the springs 24, which are pivotally mounted in like manner, is
to return the roll platform to the center position in the event
that hydraulic or electric power to the actuators fails. The
control system required to achieve proper operation of the system
will be described subsequently. The outwardly directed swing arms,
the springs 24 and the actuator 23 are clearly shown in FIGS. 3 and
4.
FIG. 5A is a schematic drawing showing the apparatus in operation
either on a straight track or a curved track at exactly the design
speed for roadbed banking. In this situation there is no
requirement for car body roll angle or lateral translation and the
two actuators 23 are extended equally. The force levels in these
actuators may be zero in this condition or they may be nonzero.
FIG. 5B shows the operation of the system when a roll angle in the
counterclockwise direction and a lateral translation of the car
body to the left is required. Upon signal from the control system,
the right-hand actuator 23 is extended while the left-hand actuator
23 is shortened. This causes swing arms 22 to rotate about their
axes 18, thereby lowering the left-hand side of roll platform 19 in
FIG. 5B and raising the right-hand side. This rolling motion of the
platform is accompanied by translation of the roll platform to the
left. When this motion takes place, the left-hand spring 24 is
compressed and the right-hand spring is extended, thereby providing
forces which would restore the roll platform to its initial
condition in the event of a failure of the actuators. It will be
understood that springs 24, due to the spacing of their coils and
their pivotal attachment, act both in compression and tension.
FIG. 6 shows the kinematics of operation of this apparatus. Line AB
represents the roll platform 19, line DC represents bolster 15,
line AD represents the left-hand swing arm 22, line BC represents
the right-hand swing arm 22. The paths of the car body center of
gravity 6 and the instantaneous roll center 7 are also shown. The
dashed lines in this figure show the orientation of the swing arms
and the roll platform after a signal to roll the car body
clockwise.
As an example, in an actual installation of this apparatus the
distance DC in FIG. 6 might be 32 inches, the distance AB might be
55 inches, the distances AD and BC might be 23 inches, and the
angle .theta..sub.o might be 60.degree.. When the swing arm AD and
BC are rotated through an angle .theta. of 30.degree. clockwise as
shown in FIG. 6, the car body roll angle .theta. would be
12.degree. and the center of gravity 6 of the car body would be
translated laterally to the right a distance of 16 inches. For this
geometry, the usable range of swing arm angles .theta. might be
30.degree. counterclockwise to 30.degree. clockwise from the
central position.
In the preferred embodiment of the invention, the output signal
from accelerometer 25 attached to roll platform 19 in FIG. 2 is
used by the control system to cause changes in the force levels in
actuators 23. For this embodiment, the control system shown in the
block diagram in FIG. 7 can be used. The output of the
accelerometer is a voltage Ve proportional to the instantaneous
acceleration of roll platform 19 in the lateral transverse
direction. This acceleration is approximately equal to the lateral
transverse acceleration that would be experienced by the passengers
in the car body. The accelerometer output voltage V.sub.e may have
to pass through the optional filter circuit 26 in order to remove
high frequency signals due to truck hunting, track irregularities
and other sources tending to cause differences between the
acceleration at the accelerometer and the acceleration of the car
body center of gravity 6. This filter circuit would be a
conventional low-pass electrical network which is well known to
those familiar with the art. The output voltage V.sub.c, or V.sub.e
if no filter circuit is utilized, then provides the signal to the
appropriate jack motors and mechanisms 23 to extend or shorten
their lengths. For example, if the accelerometer 25 in FIG. 2
indicates that the roll platform 19 is accelerating to the left, a
positive voltage V.sub.c would signal the left-hand jack motors in
FIG. 2 to decrease the actuator length and signal the right-hand
jack motors (not shown in FIG. 2) to increase the actuator length.
This would cause counterclockwise rotation of arms 22 on the
left-hand side in FIG. 2, thereby lowering the roll platform 19 on
that side. Concurrently, rotation of the swing arms on the
right-hand side of FIG. 2 would cause elevation of the right side
of the roll platform. This combined action would cause the roll
platform to roll in the counterclockwise direction and would cause
the platform to be translated laterally to the left.
An example of the type of electromechanical actuator which could be
used in this embodiment of the invention is shown in FIG. 10.
Actuator 23 is shown to consist of a jack motor 27 and a rack and
pinion device 28. When the motor is actuated by the voltage V.sub.c
the actuator 23 is caused to extend or contract depending upon the
electrical sign of voltage V.sub.c.
FIG. 8 shows an alternate embodiment in which the accelerometer 25
is also mounted upon the roll platform 19 but, instead of
electromechanical actuators being used, hydraulic actuators are
used. The signal voltage V.sub.c actuates the selector valve 29
which in turn directs high pressure hydraulic fluid into the the
appropriate chambers of the left and right-hand hydraulic actuators
23. A possible configuration for the hydraulic actuators 23 is
shown in FIG. 11 and a possible configuration for a selector valve
is shown in FIG. 12. In FIG. 11 it can be seen that the
introduction of high pressure hydraulic fluid from the hydraulic
accumulator into the top chamber above the piston 30 and concurrent
venting of the bottom chamber below piston 30 would cause a force
downward and to the right in FIG. 11 which would result in
shortening of the actuator strut. Similarly, introduction of
high-pressure hydraulic fluid into the bottom chamber and venting
of fluid from the top chamber would cause a force tending to extend
the actuator.
The control selector valve shown in FIG. 12 consists of a case 29
and a shuttle valve 30a having a plurality of passages drilled
diametrically, such as passages 31 and 32. The shuttle valve 30a is
driven longitudinally along its axis of symmetry by solenoid 33
which is energized by the signal voltage V.sub.c. Shuttle valve 30a
acts against the springs 34 such that under zero voltage conditions
the springs tend to center the valve in the neutral position. If,
as in the preceding example, an acceleration is sensed by
accelerometer 25, voltage V.sub.c is given the appropriate
electrical sign to cause the shuttle valve 30a to translate,
thereby aligning the proper passages and connecting pipes to
introduce high-pressure fluid into the proper chambers. In FIG. 12,
passage 31 would permit hydraulic fluid to leave the top chamber on
the left actuator through pipe 36 and enter the reservoir through
pipe 35; simultaneously passage 37 would permit hydraulic fluid
from the high pressure accumulator to flow through pipes 38 and 39
to the bottom chamber of the left actuator, thereby causing the
left actuator to increase in length.
The details of the wiring in the case of the electromechanical
actuations and the details of the hydraulic reservoir, pump,
accumulator and associated pipes and flexible hoses, in the case of
the hydraulic system, are not shown in these figures. These
components are well known in the art. Moreover, it is not pertinent
to the present invention to describe their locations. For
convenience, they may be located within the car body, on the roll
platform 19, on the bolster 15, or on the truck frame 12.
Still another embodiment of the invention is illustrated in the
block diagram of FIG. 9. In this case the accelerometer 25 would be
mounted on the truck frame 12 or the bolster platform 15. Since the
accelerometer does not in this case directly measure the
acceleration of the roll platform 19, its signal must be modified
by a signal from the swing arm potentiometer 40. This potentiometer
measures the angular rotation of swing arm 22 relative to bolster
15 or the roll platform 19. When the voltage output of the swing
arm potentiometer is subtracted from the Voltage Ve' as in FIG. 9,
the resulting voltage V.sub.c is equivalent to voltage V.sub.c
shown in the control system of FIGS. 7 and 8. The remaining
portions of the system function identically as described
previously. Although FIG. 9 shows the block diagram for the system
employing electromechanical actuators, this system may also be used
with hydraulic actuators.
I wish it to be understood that I do not desire to be limited to
the exact details of construction shown and described, for obvious
modifications will occur to a person skilled in the art.
* * * * *