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Патент USA US2410169

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Oct'29, '1946.
' 4Filgd July 21, 194s
am “
Patented oa. 29, 1946
- Ludger E. La Brie, Detroit, Mich., assignor to
Hydraulic Brake Company, Detroit, Mich., a
` corporation of California
Application July 21, 1943,-SerialNo. 495,638
6 Claims.
(Cl. G0L-54.6)
This invention relates to fluid pressure braking
systems, and more particularly to ñuid pressure
producing devices therefor.
vT'he invention comprehends a fluid pressure
producing device including a low pressure pro
ducing means, an intermediate pressure produc
ing means and a high pressure producing means,
and means operative upon attainment of a pre
determined‘pressure in the low and interme
diate pressure producing means respectively for
transferring the load or pressure respectively
from the low to intermediate to high pressure
producing means.
Referring to the drawing for more speciñc de
tails ofthe invention, I0 represents generally a.
fluid pressure producing device including a cyl
inder I2 adapted to be mounted in a fixed posi
tion. The cylinder I2 has one end open and its
other end closed as by a head I4 having secured
thereto concentric cylinders I6 and I8 providing
in conjunction with cylinder I2 large, inter
mediate and small chambers 20, 22, and _724, re
spectively. Cylinder I8 includes a head 26 pro
vided with a discharge or outlet port 28 com
municating with chamber 24.
Afñxed to the cylinder IIJ is a suitable con
nection 38, normally connected to a conventional
An object of the invention is to provide a
iiuid pressure producing device operative to in 15 fluid reservoir or tank 32 including a passage
crease the fluid pressure through several stages
Without increasing the applied operating force.
_34 anda> chamber 36 providing communication
>between-_the reservoir and chamber 20 by way of
passages 3`8- and 40 in the wal1 of rcylinder |72.
An object of the invention is to provide a fluid
A piston 42 reciprocable in the chamber 20 is
pressure producing device operative to effect a
transition from low to high pressure Without per V20 held against displacement by a retaining ring
ception to the operator.
v¿i4 ysecured tothe open end of the cylinder I2.
Another object of the invention is the pro
vision of a ñuid pressure producing device in
cluding a low pressure producing means, an in
. termediate pressure producing means, and a high
The-piston includes a head 46, a reduced body
portion 48 providing in conjunction with the
lwall of the cylinder I2 an annular chamber 50, _
an internal body portion 52“, and a skirt' 54’ sup
chamber and a high pressure chamber, pistons.
porting a sealing cup 56 for inhibiting seepage
of fluid from the cylinder past the piston, and
arrangedY in the back of the piston is a socket
5B. 'Chamber'EU communicates through passage
30 36, chamber 36 and passage> 34 with reservoir 32,
reciprocable in the respective y chambers, and
means in the pistons for controlling the transi
in inter-communicating chambers 60 and 62
pressure producing means.
A further object of theinvention is to provide
a fluid pressure producing means including a
low pressure chamber, an intermediate pressure
tion of pressure from the low to the high pres
sure chamber.
A still further object of the invention is to
provide a fluid pressure producing means in
cluding a cylinder having small, intermediate,
and large diametral bores, a piston in the cylinder
having heads reciprocable in the respective bores
for producing‘various stages of fluid pressure, and
a valve system inthe piston adapted to be ac
tuated by the fluid pressure developed in the
respective bores.
Other objects and advantages of the invention
will appear from the following description taken
in connection with the drawing forming part of
this speciñcation, and in Which
Fig. 1 is a diagrammatical illustration of a ñuid
pressure braking system embodying the inven
Fig; 2 is a vertical sectional View of a fluid
pressure `producing device; and
Fig. 3 is a sectional view of a modiñed form
of valve system-embodied in the fluid pressure
The body portion 5'2 ofthe Vpiston 42 has there
communicating With chamber 50 through a pas
sage 6’4, and with chamber 20 by Way of re
’stricted passages 66 and 68; The communica
"tion between chambers 60 and 62 is’controlled by
a spring-pressed ball check valve l0 adapted.v to
be actuated by a spring-pressed slide valve 'I2
reciprocable in chamber 62.
Valve 'l2 includes a projection 'I4 for associa
tion with valve -III, a projection 'I6 extended
through and'beyond a bore "I8 in body portion
Y52 of piston 42, the purpose of which will here
inafter appear, and an annular section-80 having
L' A a plurality of passages Atherethrough for control
of passage 68.
YThe head ¿36 ci piston 42 has a plurality of
ports or'passages 82 therethrough providing com
munication between the annular chamber 56 and
that portion of the large chamber 28 forward of
the' head 46, and a sealing cup 84 is seated on
the head for control of the passages.
A piston 86 includes heads 88 and l90 adapted
for reciprocation in the respective chambers 22
and V24; Piston 86 has a body portion 92‘te1e
scoping the body portion 52 of piston 42 and is
loosely coupled therewith to permit free self
alignment of the pistons in the respective cham
bers in which they reciprocate. A lock-screw 94
threaded in the body portion 92 of piston 88 in
hibits relative axial movement between pistons
42 and 86. The head 88 of piston 86 has a plu
a stub shaft |52 and connected by a retractile
spring |54 to a ñxed support |56.
In a normal operation, upon depressing the
rality of passages S6 providing communication
sealing cup 84 on the head 46 of piston 42 closes
between chambers 20 and 2.2, and a sealing cup
the passage 40, the sealing cup 98 on the head
foot pedal lever |50, force is transmitted there
from through the rod |46, resulting in advancing
the pistons 42 and 80 on the compression stroke.
During the initial movement of the pistons, the
88 is seated on the head for control of the pas
88 of the piston 86 closesoff ports |30, the sealing
cup |26 on the head 90 of the piston 80 closes
off port |32, and thereafter, as the pistons ad
Piston 86 has in its body intercommunicating
chambers |00 and |82 corresponding to cham
vance on the compression stroke, a large volume
of fluid is displaced from the low pressure cham
bers 00 and 62 in piston 42. Chamber |00 is
ber 20 through the passages 96 in the piston head
closed at one end by a ring |04 threaded in the
88, past the sealing cup 98 into the intermediate
body of the piston 88. The ring |04 receives and
pressure chamber 22, through the passages |24
supports the projection 'I6 of valve 12 for recip
on the piston head 90, past the sealing cup |20
rocation in chamber |00 and has in its wall a
passage |00 providing in conjunction with a pas
into the high pressure chamber 24, thence
sage |08 in the body portion 52 of piston 42 com 20 through the discharge port 28 and fluid pressure
delivery pipes |34 into the ñuid pressure actuated
-munication between chambers 62 and |00.
motors |36, causing energization of the motors
The communication between chambers |00 and
|02 is controlled by a spring-pressed ball check
with the resultant actuation of the friction ele
:ments i 42 into engagement with the drum |40
`valve ||0 adapted to be actuated by the ñuid
pressure chamber 22 and also by a spring-pressed 25 against the resistance of the retractile spring |44,
to take up the clearance between the friction ele
slide valve ||2 mounted for reciprocation in the
ments and drum. Because of the displacement
chamber |02. The valve ||2 includes a plunger
of a large volume of fluid, at a relatively low
||4 fitted in a bore ||6 in the head 80 of the
pressure, the friction elements are moved into
piston 86. A restricted passage ||8 and a pas
sage |20 provide communication between cham 30 engagement with the drum quite rapidly.
After a predetermined pressure has been
' bers 22 and |02, passage |20 being controlled by
reached in the chamber 20, say, approximately
the plunger portion of valve H2. The plunger
30 pounds per square inch, the pressure in cham
' ||4 of valve ||2 has passages |22 through its
ber 20 acting on the ball Valve 'i0 by way of re
body providing communication therethrough be
tween passage |20 and the chamber |02.
35 stricted passage 60 and chamber 62 cracks the
valve to thereby relieve pressure from chamber
The head 00 of the piston 80 has a plurality of
passages |24 therethrough providing communi
The fluid pressure in the large chamber 20 is
cation between the chambers 22 and 24, and a
thus relieved and a portion of the fluid is re
sealing cup |26 seated on the head controls the
passages |24, the central portion >thereof being 40 turned from the chamber through restricted pas
sage 06, chambers 62 and 60, passage 64, chamber
adapted to abut the plunger ||4 of valve ||2.
‘50, passage 38, chamber 36, and passage 34 to the
A spring |28 interposed between the sealing
reservoir 32.
cup |20l and the head 20 of the cylinder i8 serves
Concomitantly therewith, and upon further ad
to hold the sealing cup against displacement and
vance of the pistons, additional pressure will be
` also to return the pistons 42 and 86 to their
developed in the intermediate pressure chamber
retracted positions. Ports |30 and |82 in the
22, with the consequent displacement therefrom
walls of the respective cylinders I0 and I8 pro
of fluid under pressure through passages |24 in
vide communication respectively between the
the piston head 86, past sealing cup |26` into
chambers 28 and 22, and 22 and 24 when the
50 chamber 24, thence through the discharge port
pistons are in retracted position.
28 and fluid pressure delivery pipes into the fluid
`A fluid pressure delivery pipe or conduit |34
pressure actuated motors |36, causing further
y connected to the discharge port 28 of the cylin
energization of the motors with a resultant actu
der |2 has branches connected respectively to
ation of the frictionvelements |42 into engage
' fluid pressure actuated motors |36, preferably
arranged in pairs, one pair for actuating the 55 ment with the drums to provide for greater re
tardation of the drums |40.
brakes associated with the front wheels of a
Upon the attainment of a predetermined pres
vehicle, and another pair associated with the
sure in the intermediate pressure chamber 22,
brakes of the rear wheels of the vehicle.
say, approximately 60 pounds per square inch,
The brakes, which may be of any desirable
’ type, preferably include a ñxed support or back 60 the ball check valve ||0 will be .lifted from its
seat and thus provide for relief of pressure from
l ing plate |38 adapted to be secured to an axle
chamber 22 through restricted passage IIB,
or axle housing, a rotatable drum |40 associated
chambers |00 and |02, passage |06, passages |08,
» with the backing plate adapted to be secured
the passages in valve 12, chamber 62, past the
to a wheel, a pair of friction elements or shoes
|42 pivoted on the backing plate for cooperation 65 valve 10, chamber Si),> passage |54, chamber 50,
passage 38, chamber 36, and passage 34 to the
Y with the drum, a retractile spring |44 connecting
reservoir 32.
the shoes, and a motor corresponding to the
Simultaneously with the cracking of valvel I0
motors |36 mounted on the backing plate between
providing for relief of pressure on the fluid in
the shoes and operative to actuate the shoes into 70 chamber 22, the pressure is received on the' head
engagement with the drum against the resistance
90 of the piston 85, and subsequent further move
of the retractile spring.
ment of the pistons 42 and 86 produces the high
The socket 58 receives one end of a thrust rod
pressure stage of operation of the unit by the
|743, the other end of which is connected by a
development of high pressure on the fluid in
` clevis |48 to a foot pedal lever |50 rockable on 75 chamber 24 with the consequent displacement
therefrom through portï28, delivery pipesv- |34 into
the fluid pressure actuated motors |36, causing
still further energization» offthefmotors with the
resultant» actuation o_f the friction» elements-into
further engagement with the drums tol thereby
inhibit rotation of the drums.
Upon attainment> of a predetermined pressure,
say 70 pounds per square inch, in chamber 24,
actingy upon the sealing cup |26, the valve ||~2
reciprocable in chamberV |02 is moved against the
resistance of the valve spring to thus abut ball
closed atene-‘end by a ring .3M-threaded» in the
body of piston 286 havingfa passage 306 in its wal-l
and providing in conjunction with a passage 308
inthe body portion »252` of the piston 242-` .com
munication between chambers 262> and 300.
The :communication between chambers 300 and
302 is controlled by a spring-pressed ball-check
valve 3f|0V adapted to be actuated by- aV ‘spring
pressed valve 3|2 mounted for recíprocation in
10 chamber-302. A restricted passage-3 I6 in the pis
ton 286-' -provides communication betweenf- the
chambers222 and 302.>
valve H0, Which in turn abuts the projection 16
The mode of` operation of lthe modiñcation is
of- slide valve 1-2, causing movementof the valve
'substantially Videntical to that of the preferred
12 against the resistance of its spring, whereby
projection ‘i4 of the valyeabuts ballV valve 10 to 15 embodiment, the only difference being in they ab
retain it fromits seat. With vthe movement of the
‘slide valves 'l2Y and H2 from their normal posi
tions, the Vpassage 68* yin the piston 412 and the
passage |20 inthe piston 36à are uncovered to
sence of the slide valve operation between the ball
valves-_hence needs no explanation.
While this invention has been described in con
nection With certain speciñc embodiments, Vthe
thereby provide for more complete relief of" pres 20 principle involved is susceptible ofA numerous
other applications that will readily occur to perf
sure from chambers, 20> and 22 through the vari
sons skilled inthe art. The-invention is, .there
ous interconnected chambers and passages to the
fore, to be limited only as indicated by the scope
reservoir 32. The movement of valve 80 is in
oi the appended claims.
sufficient to close the restricted passage 66. The
Having thus described the various features of
complete relief of pressure in chambers 20 and 22
the invention, what I claim as new and desire to
provides for the removal of parasitic load on the
secure by Letters Patent is:
head 46 of the piston 42 and the head 86 of the
1. A fluid pressure producing device having a
piston 86 during the high ñuid pressure develop
pressure chamber, an intermediate pressure
ment stage of operation.
Upon completion of a braking operation, the 30 chamber and a high pressure chamber, a piston
having heads movable inthe respective chambers
foot pedal lever |50 is released and is returned
for creating pressure, and a loaded valve mecha
to its retracted position under the influence of
nism in the piston controlled by the differential
the retractile spring |54. This movement of the
of fluid pressure between the low and intermedi
foot pedal lever retracts the rod |46 With the
ate chambers for relieving the pressure in the in
resultant release of the pistons 42 and 86 and
termediate pressure chamber to thereby transfer
return thereof to retracted position under the in
the load from the low and intermediate to the
fluence of retractile spring |28.
high pressure piston head.
As the pistons return to retracted position, the
2. A liuid pressure producing device having a
valves 10, 12, ||0, and ||2 also return to re
low pressure chamber,- an intermediate pressure
tracted position, and simultaneously therewith a
chamber and a high pressure chamber, and a pis
partial vacuum is created in chamber 24, result
ton having heads movable in the respective cham
ing in drawing lluid from the reservoir through
bers forv creating pressure, and a valve mecha
passage 34, chamber 36, and passage 38, into the
nism comprising a pair of ball valves and a pair
annular chamber 50, thence through the passages
82 in the head of the large piston 42, past the » of slide Valves actuated by `the fluid pressure in
the chambers for consecutively relieving the pres
sealing cup 84, into chamber 20, through the Das
sure in the respective low and intermediate pres
sages 96 in the head 88 of piston 86, past the seal
sure chambers during ya pressure creating move- '
ing cup 98, into chamber 22, through the passages
ment of the piston.
|24 in the head 90 of piston 86, past the sealing
cup |26, into the small chamber 24, completely 50 3. A ñuid pressure producing device comprising
a reservoir, a low pressure chamber, an interme
filling the chambers 20, 22, and 24.
diate pressure chamber and a high pressure
During this operation iluid is returning to the
chamber, a piston having heads movable in the
chamber 24 from the fluid pressure actuated
respective chambers for creating pressure, and
motors |36 and the fluid pressure delivery pipes
valves controlling passages lthrough the pistons
|34 connecting the motors to the chamber 24.
connecting the pressure chambers and reservoir,
This may result in the chamber 24 receiving a
said valves being normally closed the valve be
quantity of fluid in excess of its capacity and in
tween the low pressure «chamber and the reservoir
this event the excessive quantity of ñuid is dis
'being first opened by a predetermined pressure in
placed therefrom through the port |32 into the
the loW pressure chamber, the Valve between the
intermediate chamber 22, through port |30, into
intermediate chamber and the ñrst :chamber be
the large chamber 20, and thence through pas
ing first opened by a predetermined differential
sage 40, chamber 36, passage 34, into the reservoir
of pressure between the intermediate pressure
chamber and the low pressure chamber, and
A modiñcation of the valve system is illustrated
means to mechanically hold said valves open upon
in Fig. 3 wherein a piston 242 includes a body
a predetermined differential between the highportion 252 having therein intercommunicating
pressure chamber and vthe intermediate pressure
chambers 260 and 262 communicating with a
chamber 220 by way of a restricted passage 266.
4. A fluid pressure -producing device compris
The communication between the chambers is
ing |a reservoir, a 10W pressure chamber, an in
controlled by spring pressure ball check valve 210.
termediate pressure chamber »and a high pressure
A piston 286 has .a body portion 292` telescop
chamber, a piston having heads movable in the
ing the body portion 252 of piston 242, and pro
respective chambers for creating pressure7 said
vides within the body portion intercommunicat
low and intermediate chambers communicating
ing chambers 300 and 302 corresponding to cham
bers 260 and 262 in piston 242. Chamber 300 is 75 with the reservoir by way of restricted passages
in the piston, and loaded valves in the communi
cation normally closing off communication,` one
low pressure chamber, an intermediate pressure
chamber and a high pressure chamber, a piston
of said valves being- exposed on one side to the
having heads movable in the respective chambers
pressure of the low pressure chamber and on the
forcreating pressure, said 10W and intermediate
other side to the pressure of the intermediate Ul pressure chambers communicating with the reser
pressure chamber.
voir, and a mechanism in the piston comprising
5. A ñuid pressure producing device having a
»a ball valve adapted to be actuated by the pres
10W pressure chamber, an intermediate pressure
sure in the 10W pressure chamber, a ball Valve
chamber and a high pressure chamber, a piston
adapted to be actuated by the pressure in the
having heads movable inthe respective vchambers
intermediate pressure chamber, a slide valve be
for creating pressure, a check Valve past which
said low pressure chamber communicates With the
tween the ball valves adapted to be actuated by
the movement of the second-mentioned valve, and
reservoir, a slide valve controlling one restricted
a slide valve adapted to be actuated by the pres-_
passage from said intermediate pressure chamber
sure in the high pressure chamber, said ñrst
to the reservoir by way of said check valve-con 15 mentioned ball .and slide valves operable to con
trolled passage and said slide valve-controlled
trol the communication between the low pressure
passage, said check valve normally closing the
chamber and the reservoir, and said second-men
communication and adapted to be fluid pressure
tioned ball and slide valves operable to control
actuated to provide for relief of pressure from the
the communication between the intermediate
respective 10W and intermediate pressure cham 20 pressure chamber and the reservoir.
6. A ñuid pressure producing device having a,
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