Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
7~
VE:HICLE AIR BRAKE
SYSTEII AND VALVES FOR IT
This application xelates generally to a vehicle air
h~a~c syscem, to .l multi-fullctioII ~alv~ and other valves
5 ~nd, in Ol~e elll~O~ llt, tG inlprovemellts in a system of
the type disclosed and claimed in U.S. Patent No.
4,685,7~ which is commonly assiyn~d with this applica-
tiOII .
Parkillg~ emergency and service air brake systems
tha~ are presently employed on trucks, trailers, trucktractors, buses and other air-brake equipped vehicles
generally include diaphra~m brake chambers for all
axles, including hoth non-steerable and steerable a~les.
Tlle pressure supply systems which are ~mployed in such
air brake systems generally comprise compressors and
reservoirs along with multiple valves employed for the
various operatiny modes oE the brake system. There are
generally -two separate air systems employed, namely, a
service or primary system, and an emergency or secondary
system. Not orlly are the valves numerous, but they vary
in complexity of construction. Such valves include
service relay valves, spring brake control valves, quick
release valves and others. Operationally, treadle
valves are commonly used for service brake applications
and operated, push-pull valves are used for parking and
er,lergency applications. Further, the power or pressure
supply equipment utilizes one-way and two-way check
valves or other protection valves to protect one air
system from another.
6~7
I~A~'ENT
't`he purposes of having -two air systems and the
ra-tller complex valving arrangements that operate there-
wi-th are mally. One purpose is to provide safety in the
event that there is a complete loss of pressure in one
of the systems or at a conllection between the tractor
and tlle truck trailer of a motor truck vehicle. A
further purpose of such systems is to allow a driver -to
release and reapply brakes in the event of pressure loss
in orle side of the system. Therefore, it is apparen-t
that safety and back-up operation are important in air
brake systems. In fact, federal and state highway
safety laws require that air systems meet certain
requirements, including not only having a
primary/secondary pressure operation, but also with
regard to providing braking for emergency and parking
operation prior to loss o~ air pressure.
The system o~ U.S. Patent No. 4,685,744 was an
improvement upon prior systems of this type in several
respects. It includes a brake assembly a~ each brake
actuator rod which contains a single diaphragm chamber.
Tlle diaphragm drives the brake actuator rod forward to
apply the brakes when a sufficient pressure is supplied
to the air receiving inlet side of the chamber. Other-
wise a return spring returns the actuator to release the
brakes. The input port to the chamber is connected to a
two-way, open-center shuttle valve, one input to the
valve ~eing connected to the service or primary air
supply and the other input to the valve belng connected
to the emergency or secondary air supply. In the
service application, the service supply pressure is
increased thereby closing the emergency input side. If
there is ~ailure or loss of pressure on either side, but
not both, the valve will shut o~f the low pressure side
and operate normally with respect to the remaining
pressurized side. The brakes include a rack and
emergency piston having a pawl end which engages and
holds the actuator in place when there is loss of supply
PATENT
pressure and -thc brakes have been actuated. Prior to
such actuation, an adequate supply of emergency air
pressure maintains the pawl end in its disengaged state.
~fter the pawl end is engaged, -then a resupply of
pressure applie~ to t~le emergency side of the shuttle
valve and to the piston will relieve the holding pres-
sure between rack and pawl, while lifting the pawl from
the rack. In the emergency brake application sequence,
the mechanical locking piston is delayed in its fall
until air bleeds off the tank or after tank pressure
reaches a predetermined level.
In some prlor systems, a pressure protection valve
on the prilnary tank prevents air flow until the emer-
gency tank is partially full.
In the U.S. Patent No. 4,685,744 system, the
service line is in communication with both the primary
and emergency systems. Thus, in service operation,
actuating air pressure is supplied by both tanks.
Another system on the market is the sendix DD3.
This is a double diaphragm, air actuated, mechanically
held brake. The mechanical locking brake assembly
includes a tapered actuator rod. The DD3 uses roller
balls il~ place of a piston rod. These roller balls are
held away from the actuator rod by air until the emer-
gency brake is applied. When applied, the actuator rodis forced forward by a smaller diaphragm to begin
applying the brakes while at the same time the air
holdillg the roller ball is exhausted and a spring forces
it down onto the actuator rod. The roller balls are
designed to move in only one direction. This allows the
actuator rod to move forward and apply the brake but
prevents the rod from moving backward and releasing the
brake.
In order to release the emergency brake, air is
applied to the smaller diaphragm as well as the roller
ball. Since the Bendix DD3 system releases the emergen-
cy brake at the same pressure as was used to apply the
--3--
2~0~7~7
PA~ENT
brake, an independent foot application is rcquired to
release the parkiny brake. The Bendix DD3 does not time
the mechanical lockiny brake. It applies the brake and
engages the roller balls simultaneously. This could
lcad ~o early colltact betwcell the actuator rod and the
roller balls and cause mechanical wear.
In one embodiment the present invention -teaches a
multifunction system for controlling and coordinating a
vehicle air brake system including a multifunction
sequencillg valve for sequencin~ and controlling pres-
surized air flow between an emeryency brake system and a
mechanical locking braking system; a primary or service
compressed air reservoir; an emergency or secondary
reservoir; a supply line for supplying compressed air to
the multifunction sequencing valve and lines and
chanllels for air flow through the sequencing valve and
to and from the reservoirs and vehicle brake assemblies.
In one embodiment a multifunction sequencing valve
according to this invention has
- a pressure protection valve (in the trailer
mode) for insuring that the emergency reser-
voir is filled first and allows brake release
before a service (secondary) tank is filled,
or vise versa;
2S ~ a pressure reduction valve for insuring that
air a-t a desircd pressure is applied to the
brakes;
- an emergency control valve for insuring the
system is charged to a certain safe level
prior to brake release; in a low pressure mode
it insures that the brakes can still be
applied at the desired pressure; opens at a
higher pressure than that at which it closes,
so system air-up is not required each time the
brakes are applied at a marginal pressure;
- a syncro valve, once brakes are applied,
i7
PATEN T
controls the locking pistons of the brakes so
they release and are applied at the desired
pressure without unnecessary wear or fric-
tional contact with push rod racks;
- ol~e-way check valve means for controlling and
directing f low to the various other valves and
reservoirs;
- a bypass valve for allowing air pressure to
bleed by ~he syncro valve to lock the brakes;
- a bypass valve to allow a peak pressure to be
achieved for brake release; and
- inlet ports for receiving compressed air from
a compressed air supply and lines or channels
through which this are can be controllingly
communicated to a compressed air reservoir or
reservoirs in an air brake system and to brake
assen~lies and other valves and apparatuses in
~he system.
The multifunction sequencing valve can be fashioned
and used to signal any other valve in the system.
The above-described valve seqUenciny can be em-
ployed With a variety of brakes~ including but not
limited to single diaphragm and dual diaphram brakes,
locking piSton bra]ces, and brakes Which have an pressure
separator valve controlling flow to a diaphragm or
diaphragms (see, e.g., U.S. Patent 4,685,744). Also
this invention is directed to systems for vehicles which
use air brakes, including, but not limited to, tractors,
buses, trucks, and trailers.
Fig. 1 is a schematic view of the channels and
valves of the multifunction controlling and sequencing
valve according to the present invention~
Fig. 2 is a schematic view of the system according
to the present invention with the multi-function con-
trolling and sequencing valve of Fig. 2.
Fig. 3 is a schematic view of the system of Fig. 1.
~0~3~3~7
PATEN T
~iy. 4 is a schematic view of a system according to
the present invention a~ adapted to truck trailers.
~'ig. 5 is a scllematic view of a system according to
the presen-t invention.
~'ig. 6 is a schematic view of a system according to
the present invention in which a trailer cannot be moved
without full pressure in hoth reservoirs.
Fiy. 7 is a side cross-sectional view of a syncro
valve accor~ing to this invention adapted for use with
coiled spring brakes.
Fig. 8 is a side cross-sectional view of an
ernergerlcy control valve according to this invention.
Fig. 9 is a side cross-sectional view of a pressure
reducing valve according to this invention.
Fig. 10 is a side cross-sectional view of a pres-
sure protectiorl valve according to this invention.
Description of Presently-Pre~erred Embodiments
Within the multi-function controlling and
sequencirly valve 10 are disposed a variety of
int~rconnected valves as pictured in Figures 1 and 2
including a syncro valve 2, an emergency control valve
4, a pressure protection valve 8, a pressure reducing
valve 11, a bypass valve 38, a bypass valve 34 which is
part of the syncro valve 2, a two-way valve 31, and
various one-way check valves 32, 33, 36, 37, and 42.
The syncro valve 2 has a supply port 2a, a delivery port
34b, and a control port 2c. The emergency control valve
4 has a supply port 4a, a delivery port 4b, and a
control port 4c and is in communication with an exhaust
port 49. The pressure protection valve has a supply
port 8a and a delivery port 8b. The pressure reducing
valve 11 has a supply port lla, a deliver port llb, and
sensor or control poxt llc. A signal port 39 is
provided in the body 56 o~ the valve in communication
with chanllels 3 and 63 in the valve 10.
pj!~Tr,N 'l'
The pressure ~rotection valve 8 is disposed in a
channel 1. The pressu~e reducing valve 11 is disposed
in a ~hannel 5. The emergency control valve 4 is
disposecl in a challnel 9. The syncro valve 2 with its
bypass valve 34 are disposed in a channel 16. A one-way
check valve 42 is disposed in a channel 3. Referring
now to Fig. 1, a one-way check valve 36 is disposed in a
channel 7. ~ one-way check valve 32 is disposed in a
channel 12. ~ bypass valve 38 is disposed in a channel
13. A one-way check valve 33 is disposed in a channel
15 .
The valve 10 and its component valves as well as
system according to this invention are described here
as used with a braking mechanism disclosed in U.S.
Patent 4,685,744 as previously described. Tt is of
course within the scope o~ this invention that its
disclc,sures can be used with other types of braking
systems and the claimed embodiments are not limited to
embodiments including apparatuses according to -this
prior art patent.
As shown in Fig. 2, in the trailer mode the one way
check valve 42 allow air to come from a primary
reservoir 28 through line 103 and channel 3 without
allowing air to flow through channel 3 to the reservolr
28. If an emergency reservoir 27 has no pressure~ the
check valve 36 allows the primary reservoir 28 to
maintain pressure. If the primary reservoir 28 has no
pressure, the check valve 42 in combination with the
pressure protection valve 8 allows the emergency reser-
voir 27 to maintain pressure. The one way check valve36 allows air to flow from reservoir 27 without permit-
ting air to flow back into reservoir 27. One way check
valve 32 allows air to fill reservoir 27 and prevents
air from flowing back to supply 61. Also air flowing
through the valve 32 eventually flows into and fills the
reservoir 28 through the pressure protection valve 8.
One way check valve 37 allows air to flow from the
s~
P~TENT
pressure re~ucing ~alve 11 at the desired reduced
pressure effected by the ~ressure reducing valve to the
emergency control valve; but the valve 37 prevents air
at a peak pressure from flowing to the pressure reducing
valve 11. The one way check valve 33 allows air at a
peak pressure from supply 61 to flow to emergency
control valve 4; but the valve 33 prevents air at a
reduced pressure from ~lowing to and through lines 15,
14 an~ 101, or port 41. The syncro valve 2 includes the
bypass valve 34. The syncro valve 2 can be adjusted for
any delay between brake actuation and engagement of
locking pistons by adjusting a spring 139 (shown in
Figure 7). If the syncro valve or its connected system
malfunctiorled, the bypass valve 34 would allow air from
port 34b to leak out from the pistons 35 effecting
piston engagement in a few seconds. The operation of the
syncrovalve 2, the emergency control valve 4, the
pressure reducing valve 11, and the pressure protec~ion
valve 8 is discussed in greater detail in connection
with Figures 7-10. It is within the scope of this
inverltion to provide a multifunction value and a system
with such a value in which the connections to the MF
valve 10, are switched so that the service reservoir 28
is filled first, releasing the brakes, and then
permitting filling of the emergency reservoir 27 so ~hat
service air will be available when the brakes are
released.
As shown in Fig. 3 in a system 50 for a trailer
according ~o the present invention employing a multi-
function controlling and sequencing (MF) valve 10
according to the present invention, the system 50
includes four brakes 21, 22, 23, 24, two on each of two
axles (not shown) of the trailer. It is preferred that
these brakes be as disclosed in V.S. Patent 4,685,744
with a two-way shuttle check valve 17, 18, 19, 20 for
each brake as described therein, but conventional spring
brakes and conventional valves may be used. The present
PATENT
inverl-tion is not limited to a number of brakes or a
number of axles.
Returning to the system 50 disclosed in Figure 3,
the MF valve 10 is connected between various reser-
voirs, flow lines, and shu~tle valve as will be de-
scribed in detail below. A supply line 101 provides a
channel for air under pressure to flow to the ~E valve
10 and from it to the other devices in the system.
push-pull parking brake apparatUS 26 is shown connected
to the supply line 101. The supply line 101 is communi-
catively connected to the MF valve.
Air from supply 61 flows through line 101, through
valve 31 and valve 32 (see Figures 1 and 2), and then
flows out the MF valve through a flow line 102 to an
emergency (secondary) air reservoir 27. Flow lines 104,
105, 106, 107 are connr~cted between the MF valve 10 and
the two-way ~huttle c-heck valves 17, 18, 19, 20
resp~ctiv~ly. ~ir flows at tlle desired pressure from
the MF valve through flow line 103 to a service (pri-
mary, supply) reservoir 28. A flow line 108 is com-
municatively connected between the MF valve 10 and a
f low line 113 (of CoUrse the conllection could be to any
of tlle common lin~s 110-112, 114) wllich extends be-tween
a relay (serviCe) valve 40 and the tWo-Way shuttle valve
20 . A f low line 109 is connected between the MF valve
10 ~ncl a flow line 116 connected between the brakes 21,
22.
A service flow line 114 is connectecl between a
typical foo-t pedal apparatus 25 on a service line and
the relay valve 40. Flow lines 110, 111, 112, 113 are
connected between the relay valve 40 and the two-way
sllut-tle valves 17, 18, 19, 20, respectively. A flow
line 115 is connected between the relay valve 40 and the
service reservoir 28.
The relay valve 40 can be of a Type R-12 relay
valve manu~actured by the Bendix Corporation Heavy
Vehicle Systems Group, or equivalent. Typically, air
_g _
~Q~C~7~7
PATENT
applied to the service port of the valve from service
line 114 f~rces a relay piston down against a biasing
spring to open a supply port connected to reservoir 28
lin~ 115 to permit flow through fo~r ~eliver ports to
lines 11~-113. varying the pres~ure on line 114 causes
the opening of the supply and deliver ports to vary
accordingly to regulate the amount of brake application.
The output from supply reservoir 28 shows for
example, four prior art brake assemblies 21-24, that are
each connected through two-way shuttle check valves
17-20 via lines 110-113. Two of these substantially
identical brake assemblies are typically connected to a
non-steerable axle, but the present invention is not
limited to use on non-steerable axles.
The system 50 of Fig. 3 has an MF valve 10, the
component valves of which are disclosed in Figures 1 and
2. The brake assemblies 21-24 are disclosed in greater
detail in U. S. Patent No. 4,658,744. To release the
brakes when there is no air in the system of the brakes
21-24, air is charged into the system through the supply
flow line 101 and to a two-way check valve 31. This air
flows through the two-way check valve 31 to a one way
check valve 32 and from there into the emergency air
reservoir 27. At this same time air is flowing to an
emeryency control valve 4 through a one way check valve
33 and to the brakes 21, 22, 23, 24 through the
emergency control valve 4 to and through lines 104-107
to the two-way shuttle valves 17-20 which control
piston- actuator rod assemblies in the brakes 21-24 as
disclosed and described in U.S. Patent 4,658,744. Air
is also flowing through the bypass valve 34 of the
syncro valve 2 to line 109 and then to the locking
pistons of the brake assemblies 21-24. Air also flows
through a one way check valve 36 and a line 55 to a
pressure reducing valve 11 then through a one-way check
valve 37 to the emergency control valve 4. At this same
time, air is flowing to and through a bypass valve 38 to
--10--
PATENT
the emergerlcy control valve 4. There is air buildiny up
against diaphragms in the brakes 21-24, which air is
trying to push the br~kes' actuator rods out and to
release pistons which are holding the rods (as shown in
the U.~. Patent 4,658,744 which in incorporated herein
entirely for all purposes~.
Now the emergency reservoir 27 is ~illing with
compressed air w~ile the diaphragm chambers on the
~rakes 21-24 are also filling, increasing pressure
beneath the pistons holding the brake actuator rods.
Once the emergency reservoir 27 has filled to a
predetermined pressure ~e.g. air at a pressure greater
than 60 p.s.i.), the pistons holding the brake actuator
rods lift u~ an~ disengage the rods. Then the air going
to a control port 4c of the emergency control valve 4
reaches the desired pressure (e.g. 80 p.s.i.) and a
delivery port 4b of the emergency control valve 4 opens
to exhaust air from diaphragm chambers of the brakes
21-24 which allows the ac-tuator rods to retract. These
rods, which push brake pads against brake drums (or
shoes against drums or discs), retract thereby releasing
the brakes.
The brakes can be released without air pressure in
the primary reservoir 28. Air from supply 61 at desired
operatiny pressure is applied to the MF valve 10 through
line 101. Emergency reservoir 27 must be working and
have operating pressure also or the supply will be
unable to sustain operating pressure ~hrough line 15a to
the emergency control valve 4 because the line will try
to supply the emergerlcy reservoir 27 through check valve
32. Therefore if the emergency reservoir 27 has no air
pressure or too little air pressure, air from supply 61
cannot reach operating pressure and the brakes cannot be
released. If the primary reservoir 28 cannot maintain
operating pressure however, then the pressure protection
valve 8 and the check valve 42 combine to isolate the
reservoir 28 from the rest of the valve 10. Therefore
~(~0~7~i~
PATENT
-the brakes can be released without pressure in the
primary res~rvoir 28.
Af-ter the brakes have been released, air, which
previously was prevented from flowing from a pressure
protection valve 8 to a service (primary, supply)
reservoir 28, reaches a pre-set desired pressure which
opens the pres~ure protection valve 8 and permits air
flow to the service reservoir 28 to begin filling it.
The brakes have been released and the trailer can move
(or is being moved) as the two reservoirs fill with
compressed air.
When the trailer is in motion and the operator of a
-tractor pulling the trailer desires to apply brakes, he
or she pushes down on the foot pedal 25 which allows
compressed air at a predetermined pressure to flow from
an air source, such as an air tank on the tractor (not
shown) into a service valve such as the conventional
relay valve 40. Opening oE the valve 40 permits air to
flow at a regulated rate from the service reservoir 28
through flow lines 110-113, to the two-way shuttle
valves 17-20 and thence into the brakes' diaphragm
chambers thereby applying the brakes.
To park a trailer wi-th the system 50 a parking
brakes apparatus is activated, e.g., pulling a button on
an apparatus 26 as shown in Fig. 3, which opens flow
line 101 permittincJ air in the line to exhaust out of
it. This also exhausts the air off oE the emergency
control valve 4 via its port 4c which moves a piston
upwardly in the emergency control valve thereby opening
up the flow of air from the port 4a to the port 4b and
thence to the diaphragm chambers of the brakes via lines
104-107 which sets the brakes for parking. Air is
-trapped in both reservoirs 27 and 28 by the one-way
check valve 32, but air still flows through a one way
check valve 42 or 36 to a supply port lla of a pressure
reducing valve 11 and thence, at a desired reduced
pressure out of a discharge port llb, to and through the
~0~7~
PATENT
one-way check valve 37 into the supply port 4a of the
emexgenc~ control valve 4 for transmission to the
brakes. When air in the diaphragm chambers of the
brakc~ uilds up to the desired predetermined level the
syncro valve sense6 this through flow lines 16, 104-107
and, in response to this pressure, a piston moves down
in the syncro valve 2 opening up bypass valve 34 so that
air is released from -the locking pistons out lines 58,
14, lO1 and valve 31 or port 41 permitting the pistons
to move down to engage and lock into the brakes' actua-
tor rods, thereby setting the brakes. If for any reason
the syncro valve 2 does not operate in this manner or if
there is not enough air pressure to operate it, air from
the brakes' piston chambers will leak out of a discharge
port 34b of the bypass valve 34 and eventually the
locking pistons will move down to engage the actuator
rods.
To release the parking brakes after the system 50
is fully charged with compressed air, the button of
apparatus 26 is pushed in. This introduces air under
pressure into the system again through flow line 101.
The air used in setting the brakes for parking flowed
through the pressure reducing valve 11 and hence is at a
lower pressure than the air now introduced into line
lOl. Suddenly there is air at a higher pressure at the
one-way check valve 33 and air pressure at the supply
line lOl is, therefore, being supplied to and through
the emergency control valve 4 onto the brakes' dia-
phragms. At the same time there is a slow restricted
flow of air into the emergency control valve via the
bypass valve 38 so that whell the button is activated on
the apparatus 26 this causes a momentary peak pressure
which effects release of the brakes quickly and effi-
ciently. In such a brake application, the brakes are
applied with reduced pressure (reduced with respect to
the level of the pressure of air from the supply 61 and
reservoirs 27, 28). Therefore applying peak pressure
-13-
~(~Q~7~
PATENT
momentarily to the brakes before piston disengagement
reduced the deleterious effects of friction or of back
pressure caused by the opera-ting mechanisms~
A balance port 41 on the MF valve 10 according to
the present invention as shown in Fig. 2 makes it
possible to have parking brakes automatically re-applied
at -the same pressure in the event a service application
is made e.g. if the foot peclal of the apparatus 25 is
depressed resulting in the raising of the locking
pistons and release of the parking brakes. Once ~he
foot pedal is released (and raised) the parking brakes
are automatically re-applied.
If the brakes are not set for parking, and -the
operator depresses the foot pedal of the apparatus 25,
the parking brakes cannot be applied in the parking mode
until the foot pedal is released (until the air off the
balance port is diminished) because the MF valve will
not permit the pressure on line 14 to be relieved which
would initiate the parking sequence until air is ex-
hausted from both service and supply sources. The twoway check valve 31 will maintain air on line 14 until
both port 41 line 101 are evacuated or no longer have
air in them (see Fig. 3), thus insuring that the vehicle
is always parked at the same desired air pressure
supplied by the pressure reducing valve. This insures
that the vehicle or trailer can only be parked at a
desired parking pressure and not at the higher pressure
of the service line 114, thus reducing problems related
to releasing the brakes and making it impossible to put
a high dangerous pressure on the brake drums.
A system 150 according to the present invention for
use with a truck tractor is illustrated in Fig. 4. In
this system the MF valve 10 has no pressure protection
valve 8 since compressed air is supplied to the two
reservoirs from a compressor 152 (or compressors) of the
truck tractor which deliver air at a desired pressure to
both a primary reservoir 154 corresponding to reservoir
-14-
~00~7~i~
PATEN T
28 of the system 50 and to a secondary reservoir 156
corresponding to the reservoir 27 of the systern 50 shown
in Fig. 3. Also there is no need for the one-way check
valve 32 of system 50 because air is supplied directly
to the emergency (secondary) reservoir rather than
through the MF valve 10. Once the reservoirs of the
system 150 are filled, pulling out the button on a
parking brake apparatus 26 allows air to flow from the
reservoirs 154, 156 to a pressure reducing valve in the
ME` valve 10 where the air pressure is reduced to a
desired level. Pushing the button will apply a peak
pressure to the diaphragms, relieving residual pressure
off the locking pistons and allowing them to freely
raise up as in the previously described trailer system
50. Since the system 150 utilizes air from the truck
compressor 152 and because of one-way check valves 160
and 162, air flows only in a direction toward the MF
valve 10 from the reservoirs 154, 156 and not vice
versa. The truck compressor 152 charges compressed air
into a common reservoir 15~ from which the air flows to
the reservoirs 154 and 156. But for the differences
noted above, the system 150 is like the system 50 and
the two function in the same manner. Similar items in
system 150 as depicted in Fig. 4 bear the same identi-
fying numerals as the items in the system 50.
A signal port 39 on the MF valve 10 shown inFigures 1 and 2 can be used as a connection to provide
air through a line (not shown) to another valve. Also
air can be supplied from either reservoir through the
port 39 without using additional check valves or lines
but simply by connecting up to the port. For example,
air could be supplied via the port 39 to another relay
valve used for another axle's parking applica-tion.
Through lines 104-107 or 116 shown in Fig. 3 a signal
can be provided by the valve 10 for signalling other
valves such as spring brake control valves.
-15-
7~7
PATENT
From the foregoing, it Will be understood that the
present system utilizes one l:ine from the air supply to
fill the reservoirs, while both the Bendix ~D3 and U S.
Patent No. 4,685,744 require two lines. The single line
eliminates the need for an extra pressure protection
valve. The present systern also provides the benefits of
two pressure levels with only one supply and delivers a
peak pressure -to overcome any friction without an
independent brake application. In addition, the present
system allows the user to control the delay betweell
brake actuation and piston engagement by the design,
selection, and configuration of the spring 139 of the
syncro valve 2, thereby allowing the user to coordinate
the brakes so that the brakes are fully actuated before
the pistons engage, and thus prevent the actuator rods
from scraping the piston rods as the brakes engage.
The present system can use only one diaphragm to
operate both service and emergency brakes (although it
can also be used with multi-diaphragm brakes). The
emergency brakes can be configured to hold as firmly as
necessary. The application pressure can be very high
and the peak pressure generated by the MF valve will
still overCome any friction. The U.S. Patent No.
4,685,744 uses only one diaphragm and only applies
additional pressure during brake release to free the
piston.
Systems according to the present invention insure
that there is air in the emergency reservoir before the
brakes are released. Air is needed in the emergency
reservoir because, with air-applied mechanically-held
brakes, there must be an air source to re-apply the
brakes.
As shown in Fig 7 the syncro valve 2 has a syncro
piston 130 and a bypass valve 34 movably disposed in the
channel 16. The syncro piston 130 has a piston face
131; a top 0-ring recess 133 in which is disposed a top
0-ring 132; a ~ottom 0-ring recess 135 in which is
-16-
)Q~
PATENT
disposed a bottom O-ring 134; a stinger 136; and a
return spring 139 which encircles the pistOIl 130. The
channel 16 has a first shoulder 137, a second shoulder
138, a third shoulder 140 and a fourth shoulder 143. A
breather tube 141 is communicatively connected to the
channel 16 and vente<l to the atmosphere.
The bypass valve 34 has a valve member 145 movably
disposed in the channel 16 and urged upwardly by a
spring 147 which is connected to the valve member 145
and $he bottom plate 30 (not shown in Fig. 7).
Air flowing from the diaphragm chambers of the
brakes 21-24 enters the syncro valve 2 through its port
2c, pushing down on the face 131 of the piston 130. The
stinger 136 moves and pushes down on the valve member
145 opening the bypass valve 34 which permits air
holding up the brake locking pistons to flow to channels
58, 14, valve 31, supply 61 and port 41 (as shown in
Figures 1 and 2) so that the locking pistons drop,
en~aging the brake actuator rods and setting the brakes.
Coaction of a stop 148 on the piston 130 and the first
shoulder 137 insure that the piston 130 can move only a
desired distance. The spring 139 pushes against the
stop 148 and the second shoulder 138. The spring 139
urges the piston 130 upwardly so that when there is
insufficient air pressure pushing down on the face 131,
the spring 139 holds the piston 130 up so that valve
member 145 is against shoulder 143 thereby restricting
flow to line 58 to delay the drop of the locking pistons
until the desired pressure can be applied against the
diaphragms of the brakes through channel 9 and lines
104-107, not shown in Fig. 7. This is the
synchronization accomplished by the syncro valve. The
piston 130 is sealed in the channel 16 by the two
O-rings 132 and 134, while air trapped between them is
vented to the atmosphere through the breather tube 141.
When the brakes are being released, utilizing the
previously-described peak pressure, air from supply 61
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7~7
PA T E N T
flows through channel 5~, syncrovalve 2, out port 34b
into channel 16 and then to the locking pistons to
release them.
To park the vehicle, as air is being exhausted
through channels 12-14, and 58, air is delivered to the
brake diaphragms, through channel 9 and lines 104-107
(see Fig. 2), and, when a predetermined amount of air
has been delivered, the piston 130 moves down, again in
response to the air pressure on the piston face 131,
opening the bypass valve 34 and thereby allowing the
locking pistons to drop setting the brakes. Whether the
piston 130 moves down or not, because of a bypass
orifice 142 in the valve member 145, air in the channel
16 from the line 116 will flow out to channel 58 and out
port 2a and the locking pistons will drop. Because of
the bypass feature of the syncro valve 2 as provided by
its bypass valve 34 and it orifice 142, flow does no~
stop through the valve 2 so that there is built in
protection against an unwanted back pressure through the
valve.
As shown in Fig. 8 the emergency control valve 4
has an emergency control valve piston 150 movably
disposed in the channel 9, which piston is urged up-
wardly by a spring 151 disposed in a recess 152 in the
pistoll 150. The piston 150 has a stinger 153 which is
movable to contact and push upwardly a valve member 154
of the valve 165 which is movably disposed in the
channel 9. A spring 156 urges the valve member 154
downwardly.
The valve member 154 is urged against a shoulder
157 by the spring 156 to sealingly prevent flow from
channel 15a into channel 9. The piston 150 has a
shoulder 158 which is urged against a shoulder 159 of
the channel 9 to prevent the crushing of O-ring 161 on
the shoulder 165.
To insure that the piston 150 is sealingly mounted
in the channel 9, an O-ring 161 is disposed on a
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~110~7
PATEI~ T
shoulder 162 on the ~iston 150 and an O-ring 163 is
disposed in a recess 164. The shoulder 162 and O-ring
161 are disposed so that upon upwar~ movemen-t of the
piston, a shoulder 165 of the channel 9 i~ sealingly
abutted by the O-ring 161 and further movement of the
piston 150 is prohibited. upon movement of the piston
150 upwardly and this contact of an~ subsequent movement
of the valve member 154 out of sealing cont~ct with the
shoulder 157, air is perrnitted to flow from channel 15a,
from the valve 4 out of port 4b to lines 104-107 (not
shown in Fig. 8), and then to the brake diaphragm
chambers to effect application of the brakes. In the
brake releasing mode, air flowing in through channel 13
and through hole 166 to push against the 0-riny 161 and
the piston, causing the piston to move downwardly and
thereby letting air flow from lines 104-107 to the
exhaust port 49 thereby releasing the brakes. Valve
member 154 seals on both face 157 and stinger 153 to
stop air flow from lSa thereby preventing further air
flow to line 104-107. When the brakes are applied, the
piston 150 moves up, urged by spring :L51 and the
exhausting of control air through the hole 166. Piston
150 removes valve member 154 form the sealing face 157
and seals the stinger 153 on the valve member 154 so
that air can flow from the channel lSa to channel 9 and
then to the brakes.
Valve member 154 sealingly contacts the shoulder
157 and then exhausting air from lines 104-107 flows
through a bore 155 in the piston 150 when it moves
downwardly and thence to the exhaust port 49. thus
making the area that air acting through hole 166 pushing
down on the piston 150 and spring 151 larger than the
area provided before the piston 150 moves down to an
inside diameter 167.
The valve 4 has built in hysteresis because of the
design of the bore of the channel 9 and the piston 150.
An inside diameter 167 of the channel 9 is greater than
--19--
~0~ ;7
PAT~NT
an inside diameter 168 of the channel 9. Therefore more
air pressure is required to open the valve and exhaust
air off the brake diaphragms than is needed to re-seat
the valve and apply the brakes. Since the diameter 168
is less than the diameter 167, it takes more pressure to
move the piston 150 downwardly than to move it upwardly
to re-seat it. Once the piston starts to move down it
reaches the area of larger diameter, and thereby the
force on the piston 150 is increased (force = pressure x
area) at which point the piston begins -to move faster.
Upon upward movement of the piston there is a concomi-
tant decrease in force and at that point the piston
beglns to move more slowly.
This built-in hys-teresis is advantageous because it
insures that there is adequate air pressure applied
against the brake diaphragms to insure that the locking
pistons are released upon air-up of the system from zero
air pressure and it insures that reservoir 27 is ade-
quately filled to re-apply the brakes. Also this
hysteresis allows the brakes to release more quickly and
at a pressure higher than that at which they were
applied. This hysteresis provides a margin of safety if
some air leaks from the reservoirs by applying the
service brakes. Such leaking air will not cause an
unwanted oscillating application and release of the
brakes which would occur if air pressure on O-ring 161
allowed the stinger 153 to unseat and re-seat the valve
member 15~. This would cause the brakes to apply and
release.
As shown in Fig. 10 the pressure protection valve 8
has a pressure protection valve piston 170 moveably
mounted in the channel 1 which communicates with the
channel 57. The piston 170 moves partially within the
valve sleeve 48. A spring 171 encircles the valve
sleeve 48 and urges the piston 170 downwardly by pushing
against a shoulder 172 on the piston 170. An O-ring 173
is disposed in a recess 17~ on the piston 170 to provide
-20-
2~0~7
PATENT
a seal to raise the piston once a valve member 176
allows air to flow from port 8a to port 8b to the
primary reservoir 28 (not shown in Fig. 10). The
pressure protection valve insures that the emer~ency
reservoir 27 is filled first since the spring 171 urges
the valve member 176 again6t the seat 225 until a
desired pressure is reached.
As shown in Fig. 9 the pressure reducin~3 valve 11
in the channel 5 has a pressure reducing piston 180
movably disposed in the channel 5 with a spring 181
disposed in a hollow recess 182 in the piston 180. The
spring 181, which urges the piston 180 upwardly, can
~ias against an inside face 183 o~ the recess 182 and
against the bottom plate 30 (not shown in Fig. 9) of the
MF valve 10. An O-ring 184 is disposed in a recess 185
on the piston 180 to insure that the piston 180 is
sealingly mounted in the channel 5. A stinger 189 on
the piston 180 can move to contact and unseat a valve
190 which is also movably disposed in the channel 5 and
which is movable to sealingly abut a shoulder 191 of the
channel 5. A spring 192 urges the valve 190 downwardly
and is biased against the top plate 29 (not shown in
Fig. 9) of the MF valve 10.
Supply air (unreduced in pressure) from bo-th
reservoirs 27, 28 (see Fig. 2) enters the pressure
reducing valve through port lla and goes out of port llb
to the brakes (through valve 37 and the emergency
control valve). Wherl pressure in the lines 104-107
reaches a desired level, this air under pressure moves
the pressure reducing piston 180 downwardly and shuts
off flow into port lla. Since this air has gone into a
larger volume (in the brake diaphragm chambers) it is
reduced in pressure. The pressure of this air is sensed
through the port llc which is in fluid communication
with the lines 104-107 via a line 6a. This produces a
relatively fast shut off of air to the brakes as
-21-
~o~a)7~
~A T E N T
compared to other valves which do not use another line
(such as llc) to sense air pressure.
The pressure reduciny valve is set a a pre-set
desired pressure by adjusting, selecting or designiny
the spring 181 so that a desired pressure is delivered
to the brakes to apply them. Air from either reservoir
can flow to the pressure reducing valve to apply the
brakes.
In systems according to this invention even if one
of the supply lines from a reservoir is broken or one of
the reservoirs is ruptured or leaking the pressure
protection valve 8 and one-way check valve 42 act as
protection means to isolate the multifunction valve from
the broken line or ruptured or leaking reservoir so that
brakes can still be applied with air from the intact
reservoir or through the intact flow line.
