Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
The present invention relates generally to air brake
systems and more specifically for ar. air brake system and a
relay valve to be used in a vehicle convertible between high-
way and railroad modes of use.
There ha~ always been a great interest in the combined
transportation of highway and rail vehicles. This has generally
; included the loading of road trailers onto flat bed rail cars
which are then transported across the rails and then driven
; to location away from the rails. Efforts have also been made
, to equip trailers with road wheels and rail wheels such that
the trailer itself forms both a road trailer and a rail car.
One such vehicle is described in ~. S. Patents 4,202,267 and
~,202,277 to Brot~ne et al. The major problem with the prior
art system including that of the above-mentioned patents is
that the designers have generally designed a brake system using
highway technology and criteria which is unacceptable for
use in a rail system.
As an example, the system in the aforementioned ~. S.
Patents use a straight air brake system to operate the brake.
In this s~stem the pressure and the brake pipe line are used
! to control a relay valve which in turn contrGls the brakes.
This style system had been used extensively in r~il vehicles
but has been replaced by ABD (air brake diaphragm) valves
wherein the valve is responsive to modulation of the brake
pipe pressure to produce its own brake con~rol signal. A
major advantage of the hB~ valves is that they provide better
' control and quicXer response as well as the capability of
providing brakiny control for a further distant or longer
;~ length train.
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Thus there exists a need for a brakins system for a
vehicle which is capable of highway and railway operation
with a rail fluid braking system meeting the standards of
the rail industry.
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SU~ RY OF THE I~VENTION
An object of the present invention is to provide a fluid
brak~ cGntrol system for a vehicle which may be used for
highway as well as rail travel which incorporates the principle
,li of modern rail technology.
Another object of the present invention is to provide a
rail brake system for use on a vehicle which is capable of
,I highway as well as rail usage.
Still another object of the present invention is to provide
a rail brake system for a vehicle which is capable of hiyhway
, as well as rail usage wherein the rail brakes are automatically
deactivated during highway use.
` Even another object of the present invention is to provide
;' a rail braking system including a control valve and a relay
valve wherein the relay valve is responsive to low pressure in
, the reservoirs of the control valve.
Still even a further object of the present invant.ion is
to provide a rail fluid braking system including a control
¦ valve and relay valve wherein the relay valve provides an
' emergency brake signal on the brake line for low pressure in
th~ rail supply line or rail reservoir.
An even further o`~ject of the present invention is
to provide a brake control system for a vehicle which is
capable of highway as well as rail travel wherein the suspension
; system and the reservoir of the braking system for each car
,! are maintained charged by the rail supply line and the hiahwa~
supply line.
These and other objects of the invention are att~ined
by providing a fluid brake control system including a brake
control pipe, a control valve responsive to the change of
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I pressure in the brake control pipe to provide a control signal,
l a rail supply line and a highway supply line, and a relay
" valve assembly responSive to the control signal from the
control valve and other sensed conditions to provide the
appropriate brake cylinder pressures and signals. Th~ relay
valve assembly is responsive to the presence of predetermined
pressure in the hishway supply line for maintaining the rail
brake cylinder deactivated by connecting the rail brake cylinder
to an exhaust port. A load responsive, movable fulcrum lever
~ interconnects a first piston responsive to the control signal
from the control valve and a self-lapping relay valve piston
which connects a rail reservoir to the rail brake cylinder. A
piston in the relay valve assembly whose axis is colinear with
the relay valve a~is is responsive to low pressure in the
~ au~iliary reservoir of the control valve to actuate the relay
valve independent of the variable load fulcrum. Check valves
in the relay valve assembly interconnect the highway suppl~
line and the railroad supply line to a rail reservoir and the
rai~ suspension system such tha~ the rail suspension system
, and the rail reservoir are maintained fully charged irrespective
of the mode of use of the vehicle. Ihe relay valve assembly
includes a piston valve responsive to low pxessure in the rail
supply line to interconnect the brake pipe to exhaust thereby
' creating an emergency pressure drop in the brake pipe so that
j the control valve will produce an emeraency braking signal to
the relay valve assembly.
Other objects, advanta~es and novel features of the present
' invention will become apparent from the follGwing detailed
; description of the invention when considered in conjunction
with the accompanyins drawinss.
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3RIEF DESCRIPTION OF THE DR~WINGS
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Figure 1 is a block diagram of the brake control system
incorporati..g the principles of the present invention for
; use on a vehicle capahle of highway and rail use.
Figure 2 is a cross-sectional representation of a relay
valve assembly incorporating the principles of the present
invention.
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DESCRIPTION OF T~ PREFERRED E~BODIMENTS
As illustrated in Figure 1 each car includes at least
a pair of rail wheels 10 a brake shoe 12 and a brake cylinder
14 as well as a suspension 16 illustreted as an air spring.
It shculd be no~ed that some vehicles which are capable of
rail as well as highway use include one pair of wheels and
appropriate brakes or may include two pairs of wheels and
appropriate bra~es. For sa~e of illustrakion Figure 1 ~hows
a single wheel and brake connected to the fluid brake con-
trol system. Each car or trailer includes a bra~e pipe
18 and a rail supply line 20 both extending the length of the
car with couplings at each end to a preceding and following
car.
The fluid brake control system includes a control valve
22 haviny an emergency reservoir 24 and an auxiliary reservoir
26 Control valve 22 may be an ABDW valve which is responsive
to a change in pressure in the brake pipe to provide a
proportional output from the auxiliar~ reservoir 26 as a con-
trol signal CV. For an emergency condition or pressure drop
in the brake pipe the control valve ~2 provides an emergency
control signal CV using both the auxiliary reservoir 26 and
the emergency reservoir 24. The operation of the ABDW valve
is well known and thus ~ill not be described in detail.
The control signal CV from the control valve 22 is an
; input or pilot signal to the relay valve assembly 28. As will
be evident from the description of the relay valve assembly
in Figure 2 the control signal CV is a pilot signal and
the volume of the relay valve assembly in which it acts is
relatively small. Thus the auxiliary reservoir 26 and the
emergency r~servoir 24 may be substantially smaller than
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those used with a standard control valve 22. It sho~ld be
noted that the volume of the relay valve assembly 28 which
is responsive to the control signal CV is even so small that
; a volume 30 must be provided such that the combination of
the volume 3~ and the relay valve assembly 28 which receives
a control valve signal in relationship to the auxiliary
reservoir 26 and emergency reservoir 24 is proportional to
the relationship of a brake cylinder and a ~ull service
' auxiliary reservoir and emergency reservoir. It should be
noted that the volume 30 may be deleted if suficient volume
is provided in the relay valve assembly 28.
The relay valve asse~ly 28 incl udes an input from rail
~ supply line RSL 20 as well as highway supply line ~SL. These
; are used through the relay valve assembly to charge the rail
, reservoir 32 and the rail suspension supply 34. Air spring
16 is charged by the rail suspension supply 34 as is well known.
'~ As will be explained more fully in relationship to Figure 2,
the relay valve assembl~ 28 maintains the rail reservoir 32
and the rail suspension supply 34 charged using either the
,~ rail supply line RSL or the highway supply line ~SL. In normal
operation, the relay valve assembly 28 cor,trols the pressure
BC to the brake cylinder 14 in response to the control signal
CV using fluid from the rail reservoir 32. The relay valve
; assembly 28 is a variable load relay valve including a load
sensor 36 connected to the air spring 16. This provides a load
signal AS. The operation of the relay valve in response to
control signal CV is varied using the load signal AS.
The relay valve assembly 28 is also responsive to the
presence of a predetermined fluid pressure in the highway supply
line HSL to deactlvate the brake cylinder 14 by connecting it
to the exhaust port EX. This prevents the brake 12 rom being
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actuated when the vehicle is being used in the highway mode.
Pressure in the au~iliary reservoir 26 of the control valve
22 is monitored by the xelay valve assembly 28. For a low
pressure in the auxiliary reservoir 26, the relay valve assembly
28 applies a large brake signal from the rail reservoir 32 to
the brake cylinder 14. Thus if the auxiliary reservoir 26 has
a low level, the relay valve assembly will actuate the brake
since the control valve is not capable of providing a control
signal CV to actuate the brake in response to an appropriate
signal on the brake pipe 18.
For a ruptured, disconnected or otherwise inoperable rail~
road supply line or rail reservoir, the relay valve assembly 28
connects the brake pipe 18 to exhaust so as to crea!e an emergency
pressure drop in the brake pipe. The control valve 22 detects
the emergency pressure change an~ applies an emergenc~ control
sisnal CV to the relay valve assembly 28 ~hich in turn applies
an emeryency brake condition to the brake cylinder 1~.
The relay valve assembly is illustrated in detail in
Figure 2 and includes a housing 40. The railroad s~pply line
RSL is connected via passage 42 havinc restriction 44 and
passage 46 to a check valve 48. The output of the check valve
is connected via passage 50, valve 52 and passage 5~ to the
rail reservoir RR. The other side of the check valve 48 is
also connected via passaqe 50 and valve 56 to the rail suspension
supply RSS. The highway supply line HS~ is connected via
passage 58 to check valve 60 with the other side being connected
; to passage 50. Thus, it can be seen that the xail suspension
supply RSS and the rail reservoir RR may both ~e char~ed
either by the rail supply line through chec~ valve 48 or
the highway supply line through check valve 60. It can also
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be seen that a lea~ downstream of check valve 48 that is larger
than the flow or maintaining capabilities of restriction 44 will
create a pressure drop in passage 42. It can also be seen that
a pressure drop in rail supply line can also cause a pressure
drop in passage 42.
; Passage 42 is connected to the top of diaphragm 62 of brake
; pipe vent valve 64. The pressure on the top of diaphragm 62
from passage 42 acts aoainst spring 66 on the bottom of the
diaphragm. The space underneath the diaphragm is vented to
exhaust via port 68. Piston 72 is connected to the diaphragm 62
and its movement controls check valve 72 which lnterconnects the
brake pipe BP and the exhaust EX. Spring 66 is selected such
that when the pressure in passage 42 drops below a predetermined
pressure, for example 80 p.s.i., the spring 66 forces the piston
70 against the chec~ valve 72 to connect the brake pipe BP to
exhaust EX. This creates an emergenc~ rate of brake pipe pressure
reduction that will be sensed by control valve 22, which will
in turn react and propagate the emergenc~ rate throughout the
train. Each car will sense the emergency brake rate reduction
and so control the remainder of the re~ay valve assembly to
brake each of tl~e cars. Not only does this give an incication
of a falluxe in the railroad supply line or rail reservoir, but
by providing an emergenc~ brake sisnal to all the cars~ the
undesirable application of vehicle-equjpped spxing brakes which
is held released with rail reservoir pressure, does not go
und~tected.
The control signal CV fro~ the control valve 22 is applied
through passage 74 to the top of diaphragr 76 which ~iill rest`
on piston 78. ~ spring 80 ~aintains the piston 7~ in its utmost
position. The piston 78 is pivotall~ connected at 82 to a lever
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84. The opposlte end 86 of lever 84 is received in the base of
. piston 88. A roller fulcrum 90 determlnes the mechanical
force relationship between the piston 78 and 88. The roller
I fulcrum 90 is rotatably mounted at one end of piston 92
! which is held to the far left position by spring 94. The
other end of piston 92 rests against diaphragm 96. The
. opposing side of the diaphragm is sensitive to the sensed
load o~ the vehicle via air spring signal AS. For an air
~ spring sisnal below the rating of the spring 94 the roller
~ fulcrum is in the position illustrated in Figure 2 t~hich is
considered an 18~ location compared to the 100% location in
phantom. These percentages are the transfer or the relationship
of the control signal CV to the o~tput braking signal BC. ~
; Thus for the lightest load the brake cylinder pressure signal
is 18% of the control signal CV and for a full load the brake
cylinder pressure is 100~ of the control signal CV.
Over piston 88 is diapnragm 98 and spool 100 and return
; spring 101 of self-lapping spool valve lC2. The oùtput channe~
. 104 from the relay spool valve i02 is connected to the interior
channel 106 of spool 100 to e~haust channel 108. Output channel
104 is also connected by passage 110 anà restriction 112 to
the top of diaphragm 98. Passage 114 connects the out.put of
passage 104 of the valve to the top of check valve 116 which
interconnects the output passage 104 anc a fluid passage 118
. connected to the rail resexvoir RR.
Connected between the output passage 104 of the relay
spool valve 102 and the passage 120 connected to the brake
cvlinder BC is a brake cylinder release valve 122. The piston
124 of the brake cylinder release val~e 122 rests on the top
surface of a diaphragm 126. The highway supply line HSL is
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connected through passages 58 and 128 to the other side of
diaphrasm 126. The piston 124 is hollow and includes a passage
130 which interconnects the output lCa of the relay spcol valve
102 and the brake cylinder via passage 120 when in the position
shown in Figure 2. The pressure and output of passage 104
is also communicative via passage 132 to the top of check valve
134 of the brake cylinder release valve 122 to cause it to be
remained seated. Spring 136 maintained the check valve 13~
seated an spring 13~ maintains the plunger 124 in its down or
iowered position.
When the vehicle is to be used in the highway mode, highway
supply line HSL is activated and connected to passages 58 and
128 which provides a press~xe on the bottom of diaphragm 126.
~ox a preselected pressure, for example 25 p.s.i., plunger 124
is raised closing the passage 130 of the plunger agai~st the
check valve. This cuts off the communication between the
output 104 of the relay spool valve 102 and the brake cylinder
passage 120. Upon the pressure rising above the predetermined
?ressure, the plunger continues its upward movement opening
~he check valve 124 thereby interconnecting the brake cylinder
and the brake cylinder passage 120 to exhaust port 140. Thus,
when the vehicle is connected for highway use as detected by
brake cylinder release valve 122, the relay spool valve 102 is
cisconnected from controllins the brake cylinder and the brake
~ cylinder is connected to exhaust thereby deactivating the
brake cylinder. This prevents the brake cylinder from
operating while in the highway mode. This is important since
if the brake cylinder was locked in the highway mode even though
the rail wheels are not on the ground, severe damage may occur
to the rail wheels if they should hit the ground and not be
ree to spin.
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With the brake cylinder release valve 122 in the position
illustrated in Figure 2, the output 104 of the self-lapping
release spool valve 102 is effectively connected to the brake
cylinder passage 120. When the control valve 22 senses a
brake pressure reduction, and responds by generating a control
signal CV to passage 74 of the relay valve assemkly 28. This
signal on diaphragm 76 drives piston 78 downward which affects
an upward motion of piston 88 through lever 84. The actual
displacement of pistGn 88 ls a function of displacemer.t of
piston 78 and the position of the movable fulcru~ 90 which
varies with the sensed load. The piston 88 drives spool 100
up~ard such that the interior passage 106 is sealed closed
against the check valve 116. This disconnects the brake
cylinder passage 120 from the exhaust port 108.
Further removemerlt o. piston 88 and spool 100 unseats the
check valve 116 and allows fluid under pressure from the
rail reservoir RR through passage 118 to be ported through
passages 104, 130 and 120 to the brake cylinder on the vehicle.
The fluid pressure from rail reservoir passage 118 is
also applied through paSSaCJe 110 to the top of diaphragm 98
which forces the piston 88 in the opposite direction or downward
when the back pressure from the brake cylinder is greater than
the force created by the control signal via piston 78 and
lever 84. Thus, the relay spool valve 102 matches a brake
cylinder pressure with the pressure on piston 88 which is a
function of the control valve signal CV as varied by the
sensed load.
The relay valve assembly 28 also includes an auxiliary
reservoir protection device 141. The diaphragm 142 is connected
by passage 144 to the auxiliary reservoir and is mounted to a
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. plunger 146. Springs 148 and 150 force the plunger 146 upward
'. and is maintained in its down position by the.pressure of the
auxlliary reservoir. When the pressure in the auxiliary
~ reservoir and passa~e 144 is less than a predetermined pressure,
. for example 32 p.s.i., the springs 148 and 150 cause the
plunger 146 to rise coming into contact with plunger 88 to
acti~ate the relay spool valve 102. It should be noted that
, the axis or plunger 146 is co-linear with the axis of plunger
, 88 and both of which are parallel to.the axis of plunger 78
~ of the control valve signais CV. This feature maintains the
integrity of the re~.ay valve assembly 28 to apply pressure to
the brake cylinder from the rail reservoir RR regardless of
the status of the auxiliary reservoir of the control valve 22.
. Thls feature is necessary when the vehicle has been used
extensively in the highway mode and then parked on a rail
siaing with fully charged rail.reservoirs but depleted au~iliary
reservoir.
In the preceding description of the preferred embodiment.,
it is evident that the objects of the invention are attained
. in that a fluid control brake system for a vehicle which is
capable of highway and rail use is provided with many necess~ry
features and compatibility with rail systems. Al~hough the
invention has been illustrated and descrlbed in detail, it is
evident that this is by way of illustration and example only
! anà is not to be taken by ~ay of limitation. The relay valve
assembly 28 as illustrated in Figure 2 is but an example of
one layout of the resuirec valves and elements and other
layouts may be constructed. The essence of the present inven-
tion is the use of specific valves performins specific functions
and the fluid communication of the different elements and
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not necessarily the layout. Although the brake control system
as illustrated in Figure 1 shows many distinct elements, the
; relay valve assembly 28 is an integrated unit and may be
mounted to the face of a control valve 22 thereby eliminating
extended interconnections. Although the relay valve assembly
28 was designed for the rail brake system of a vehicle having
rail and highway modes, certain features of the valve assembly
are unique and distinct within themselves and may be used on
any rail brake system. Thus, the spiri~ and scope of the present
invention are to be limited only by the terms of the appended
~ claims.
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