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Патент USA US2112356

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Patented Mar. 29, 1938
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y
UNITED STATES PATENT OFFICE
PRESSURE PRODUCING DEVICE
. Clarence H. Bock, Detroit, Mich., assignor to
i `Hydraulic Brake Company, Detroit, Mich., a
corporation of California
.
Application December 14, 1935, SerialNo. 54,507
5 Claims.
(Cl. 60-,-54.6)
This invention relates t0 fluid pressure` brake ' yviding a communication between the cylinder and
l systems and more particularly to fluid pressure
producing devices for such systems.
Heretofore in the construction of fluid pressure
5 producing devices havinga fluid reservoir, a cylinder supplied therefrom, >and a piston recip-
the chamber, and this port is controlled by a
valve mechanism housed in the chamber. The
cylinder also has a discharge port 26 controlled
by a two-way valve 28.
`
5
As shown, the valve mechanism for controlling '
rocable in the cylinder,` _the cylinder has generally
the port 24 includes a double diametral'piston 3D
been supplied with two ports providing communications> between the cylinder and the reservoir.
reciprocable in the chamber I8 and a hollow plug
32 threaded in the open end of the chamber hav
10 These ports are generally known as the supply
port and the compensating port. The latter is
located slightly in advance of a flexible cup seated
ing an aperture 34 providinga communication be- 10
tween the chamber and the reservoir IIJ. The
plug 32 receives the small end of the piston, and
on the head of the piston when the piston is in
retracted position. Hence, when the piston is
15 moved on its compression stroke the pressure
created in thecylinder forces the wall of_ the cup
a set screw 36 in the wall of the plug limits the
movement of the piston.
`
» The piston has oppositely disposed heads 38 15
and 40 and a projection 42 on the head 40 hav
into the port and this results in serious injury to
the cup. The present invention aims to over-
ing a frusto-conical end 44 adapted to seat `in
the aperture 34 in the plug 32. The body of the
come this objection.
`
An object of the invention is to provide a com-
piston and the projection 42 are axially bored
to provide a chamber 46 and a passage 48 com- 20
bined supply and compensating port for a ñuid
pressure producing device.
municating with the chamber 46, and the passage
48 communicates `with a diametral passage ‘50 in
`Another object of the invention is to provide a
fluid pressure producing device including a reservoir, >a cylinder communicating therewith, a
piston reciprocable in the cylinder, and means
the projection 42.
for control of the communication betweenr the
interposed between the plug 32 and the shoulder
reservoir and the cylinder so that thel commu-
on the piston normally urges the piston toward
nication functions as a combined supply and com-
the bottom of the chamber I8 to move the ‘frus
. «0 pensating port.
f
tro-conical end 44 on the -projection 42 from its 30
Other objects of the invention will appear from
the following description taken in connection
seat in the aperture 34 to establish communica
tion between the reservoir I Il and the cylinder
with the drawing which form a part of this spec-
22.
ification, and in ‘which,-35
u
A leak-proof cup 52 sleeved on the projection
42 and seated on the head 40 provides against 25 '
seepage of fluid past the piston, and a spring 54
Fig. 1 is a schematic view of a ñuid pressure
brake system embodying the invention;
Fig. 2 is a vertical sectional View of the ñuid
pressure producing device of the system snowing
the positions assumed by the parts while the sys-
’
The passage 48 is controlled by a ñap valve 56
having a restricted opening 58.
A spring 60 35
interposed between the valve 56 and a ring washer
62, pressed into the open end of the chamber 46,
normally urges the valve 56 to its seat, and a
leakproof cup 64 held on the head 38 of the pis
«i0 tem ls under pressure; and
Figure 3 is an enlarged view of the mechanism
ton by a spring 66 provides against seepage of 40
iluid past the piston. The valve 56 with its re
lnterposed between the compression cylinder and
the reservoir showing the parts in the positions
assumed when the system is not under pressure.
45
Referring to the drawing for more specific de-
Stl'iC’Ged Opening 58 COOpSI‘a’CeS in the Creation 0f
suflicient pressure beneath the >piston valve 3U
to close this valve against the resistance of the
spring 54 when pressure is created in the cylin- 45
tails of the invention, IIJ represents a reservoir
der 22.
,
having a ñlling'cpening I2 which may be closed
A fluid pressure delivery pipe or conduit 68
by a plug I4 having openings I6 for venting the
suitably connected to the discharge port 26 has
reservoir to the atmosphere. The reservoir has
50 a dependent sleeve or chamber I8 communicating therewith and vented to the atmosphere as
indicated at 20, the purpose of which will here>inafter appear.
'
Acylinder 22 formed normal to the base of the
chamber I8 has a port 24 adjacent its head pro-
branches connected respectively to iiuid pressure
actuated motors ‘I0 arranged for the actuation of 50
brakes associated with the wheels of a motor
vehicle. 'I'he brakes may be of conventional type
arranged in pairs, one pair for the front wheels
of the vehicle and the other pair for the rear`
wheels of the vehicle.
'
55
2,112,856
As shown, each of the brakes includes a fixed
support or backing plate 12, a rotatable drum
14 associated therewith, a pair of corresponding
interchangeable friction elements or shoes 18
pivoted on the backing plate, and a fluid pressure
actuated motor corresponding to the motors 10
arranged on the backing plate and operative to
‘
t
move the shoes into engagement with the drum
Although this invention has been described in
against the resistance of the retractile springs 18
connection with certain specific embodiments,
the principles involved are susceptible of numer~ 10
10 connected between the shoes.
'
A piston 80, reciprocable in the cylinder 22, is
retained in the cylinder by a washer 82 seated on
an annular shoulder in the open end of the cylin-'
der and secured in'place by a retaining ring 84
15 seated in a groove in the wall of the cylinder. A
leakproóf cup 86 seated on the head of the
piston is held against displacementby a spring
88 interposed between the cup and the two-way
valve 28. T'his vspring also serves to return the
piston to its retracted position." > A >recessßß in
the back of the piston receives one end of a
thrust pin 92 on the other end of which is a cou
pling 94 connected by a flexible boot 96 to the
open end of the cylinder for the exclusionof dust
25 and other foreign substances.
The coupling 94
is connected by a rod 98 to a foot pedal lever |00
pivoted on a suitable support |02, and the lever
is connected by a retractile spring |04 to a fixed
support |06.
30
v
passage 48 in the piston, and the port I4 to the .
reservoir.
It will be observedl that should any expansionk
or contraction of the fluid occur in the system
due to changes in temperature, such expansion 5.
or contraction is readily compensated for by the
flow of fluid through the port 58 in the valve 58.
'
In operation, upon depressing the foot pedal
lever |08 force is transmitted from this lever
to the piston 88, resulting in moving the piston on
its compression stroke. During the initial move
ment of the piston the fluid under pressure in
,35 the cylinder 22 and the chamber I8 causes actua
tion of the piston 30 resulting in closing the port
34 and thereby cutting olf communication be
tween the cylinder 22 and the reservoir. Upon
further movement of the piston on its compres
40 sion stroke fluid is expelled from the cylinder
22 past the two-Way valve 28, which inhibits
retrograde movement of the fluid, and through
the fluid pressure delivery pipe 68 and its branches
into the fluid pressure actuated motors 10, caus
45 ing actuation of the motors with the resultant
spreading of the shoes 16 into engagement with
the drums against the resistance of the retractile
springs 18.
Upon release of the foot pedal lever |00, this
50 lever is returned to its normal position under the
influence of the retractile spring |04. As the foot
pedal lever moves to its retracted position, the
thrust pin 92 connected thereto is retracted. This
results in release of the piston 80, whereupon the
55 spring 88 becomes effective to return the piston
to its retracted position. Upon the initial move
ment of the piston on its retraction stroke, pres
sure on the piston 30 is released and the piston
moves under the influence of the spring 54 to
60 its retracted position, resulting in opening the
port 34 and thus establishing communication be
tween the cylinder 22 and the reservoir I0. Upon
further movement of the piston on its retraction
stroke, fluid is drawn from the reservoir through
65
the passage 48 in the piston 30, past the valve 58
which moves downwardly to permit free flow of
fluid from the reservoir to the cylinder 22, and
through port 24 into the cylinder 22.
During ,this operation fluid is returning to the
cylinder 22 from the motors 'l0 under the in
fluence of the retractile springsv'lß, and when the
cylinder is filled any fluid in excess of the quanti
ty required to completely lill the cylinder is re
75 turned through the port 58 in the valve 56, the
ous other applications that will readily occur to
persons skilled in the art. 'I'he invention is,
therefore, to be limited only as indicated by the
scope of the appended claims.
Having thus described the various features of 15
the invention, what I claim as new and desire to
secure »by Letters Patent is,
1. A fluid pressure producing device comprising
a reservoir, a chamber communicating therewith,
a cylinder communicating with the chamber, a 20
piston reciprocable in the cylinder, a piston valve '
reciprocable in the chamber and having a pas
sage therethrough, a valve for control of the pas
sage, said last mentioned valve having a restrict
ed opening therethrough registering with said 25
passage, said piston valve being normally posi
tioned to provide communication between the
cylinder and reservoir and being responsive to
the increase of pressure in the cylinder upon ad
vance of the piston to close such communication, 30
and means for actuating the piston.
_ 2. A iiuid pressure producing device compris
Ing a reservoir, a chamber communicating there
with, a cylinder communicating with the cham
ber, a piston reciprocable in the cylinder, a pis
ton valve in the chamber for control of the com
munication between the reservoir and the cham
ber, said piston valve having a passage there
35
through, said piston valve being normally posi
tioned to provide communication between the 40
'reservoir and chamber but being responsive to
the increase of pressure in the cylinder upon ad
vance of the piston to close such communication,
a spring pressed valve controlling the passage in
the piston valve, said spring pressed valve having
a restricted opening therethrough registering
with said passage, and means for actuating the
piston.
*_
' 3. A iluid pressure producing device compris
ing a reservoir, a chamber communicating there
with, a cylinder having an inlet port providing
communication between the chamber and the
reservoir and a discharge port, a piston recipro
cable ln the cylinder, a piston valve in the cham
ber for control of communication between the
,reservoir and chamber, said piston valve having l
a passage therethrough, a spring pressed valve
for control of the passage and having a com
pensating port, said piston valve being normally
positioned to open said inlet port but being re 60
sponsive to the increase of pressure in the cyl
inde? upon advance of the piston to close ythe
inlet port, and means for actuating the piston.
4. A fluid pressure producing device compris
ing a reservoir, a chamber communicating there 65
with, a cylinder having an inlet port providing
communication between the chamber and the
reservoir and an exhaust port, a piston recip
rocable in the cylinder, a piston valve in the
chamber for control of the communication be
tween the reservoir and the chamber and having
a passage therethrough, a spring normally re
taining the piston valve in inlet port opening
position, a spring pressed flap valve for control
of the passage in the piston valve, said flap valve
2,112,356
having a compensating port, said piston valve
‘
,
3
discharge port, a piston reciprocable in the cyl
being responsive to the increase of pressure in ' inder, a piston valve in the chamber for contml
the cylinder upon advance of the piston to close
the inlet port, and means for actuating the pis5 to .
\
‘
5.` A iluid pressure producing device comprising a reservoir, a chamber communicating there'11th. l cylinder having an inlet port providing a
communication between the chamber and the
10 . reservoir and the discharge port, a two-way valve
for `control oi the discharge port. fluid pressure
actuating motors operatively connected to the
of communication between the reservoir and the
chamber and having a passage therethrough, a
spring-pressed flap valve for control of the pas- 5
sage and having a compensating port, said pis
ton valve being normally in position to open said
inlet port but being responsive to the increase of
pressure in the cylinder upon advance of the
piston to close the inlet port, and means for ac- 10
tuating the piston.
~
CLARENCE H. BOCK.
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