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Патент USA US2411458

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Nov. 19, 1946.
w,-F, PENRosE i
I
ì
2,411,458 `
BOOSTER BRAKE HECHANISI
Filed July 31, 1944 v
2 Sheet‘s-sneetvi `
v
Patented Nov. 19, 1946
` 2,411,453
UNITED STATES PATENT OFFICE.
2,411,458
f'
BOOSTER BRAKE MECHANISM
V
William F. Penrose, Newark, N. J ., assignor to
Empire Electric Brake Company, Newark, N. J.,
a corporation‘of New Jersey
Application .nay 31, 1944, serial No. 541,363
l
12 Claims.
(o1. iso-54.5) '
'I'his invention relates to power brake mech
anisms, and more particularly to a booster hy
draulic brake mechanism of the type shown in
the copending application of Rudolph J.
Klimkiewicz, Serial No. 504,451, iiled September
30, 1943, now Patent No. 2,377,699.
Booster brake mechanisms of the type referred
to have been developed >for assisting in the ap
plication of braking >pressures to the hy »f .
draulically operated wheels of a motor vehicle.
Devices of this character generally utilize fluid 10
displaced from the master cylinder for taking
up play between the brake shoes and brake
drums, after which pressure is built up in the
system to actuate a motor to boost the pressure
applied to the brakes. Generally, the pressure
developed in the master cylinder is added to the
motor-developed pressure to produce a resultant
braking pressure substantially higher than that
_ ,
thus permitting the use of a shorter pressure
cylinder construction in the booster.
More specifically, an important object of the
invention is Ato provide a novel ñuid control.’
meansv for insuring more positive flow of fluid
directly from the master cylinder to the wheel
cylinders than can take place from the chamber
in which ñuid pressure Vacts to move the
manually operable piston, thus insuring against
substantial movement of such piston until a rela
tively great volume of duid has flowed from the
master cylinder to the wheel cylinders to take
up play between the brake shoes and the brake
Other objects and advantages of the invention
will becomey apparent during the course of the
following description.
'
In the drawings I have shown on embodiment
'of the invention. VIn this showing-_
`
Such mech- `
Figure 1 is an axial sectional view through the
20
anisms employ means for providing ‘for a direct
booster brake mechanism, the master cylinder
developed in the master cylinder.
ñow oi' brake ñuid from the master cylinder to
take up play between thebrake shoes and the
brake drums, and such means is closed to dis
connect the master cylinder from -the brake
and the brake cylinders together with their con
nections with the booster brake mechanism being
diagrammatically represented,
-
Figure 2 is a transverse sectional View taken
cylinders-upon actuation ci the motor or upon 25 substantially on line 2-2 of Figure 1,
actuation of the manually operated piston which Figure 3 lvis an enlarged fragmentary axial `
controls actuation of the motor.
-
A
In `such a mechanism the passage or other
means which provides for the flow of fluid from 30
the master cylinder direct to the brake cylinders
sectional view showing the low pressure> cylinder
and the flow control device associated therewith,
and
,
Figure 4 is an- enlarged side elevation of the
ordinarily provides for a'relatively unrestricted
flow control valve.
flow of brake fluid. However, a rapid operation
of the master cylinder can, and frequently does,
_ Referring to Figure 1, the numerals I0 and ii
'
respectively indicate alined high and low pres
' operate the manually controlled piston to actuate 35 sure cylinders of a booster mechanism between
the booster motor and to close direct communi
which is arranged a booster motor indicated as
cation between the master cylinder and the brake
cylinders before play has been taken up between
a whole by the numeral I2. This motor is pref
erably of the differential fluid pressure operated
the brake shoes and brake drums. To take care
type and comprises casing sections i3 and
of such a situation it is necessary that the high 40 Il of generally conical shape secured at their
pressure cylinder used in such a mechanism be' of
ends to the respective cylinders i0 and il.
such length as to permit displacement/from the
A pressure movable unit indicated as a whole by
high pressure cylinder of the iluid necessary 'to
the numeral IB is arranged in the motor and
both engage the shoes with the brake drums and .
comprises a iiexible diaphragm Il and a dia
to eiîect the maximum braking force in the event 45 phragm I8, the peripheral portion of the dia
direct communication from the m-lster cylinder
phragm being arranged between the adjacent
and the brake cylinders is cut oiï prior to engage~ . ilanges i9 of the motor casing sections and
ment of the brake shoes with the drums. `
clamped in position by a split band 20, the ends
A_n important object of the present invention
of which may be secured together in any suitable
is to provide novel means for preventing sub
manner, for example, by a wire 2i (Figure 2).
stantial operation of the manually operable
The diaphragm l1 is secured to the plate |81 by a
motor-controlled piston until all, or substantially
vsnap ring or encircling wire 22 (Figure 1).
all, oi’ the iiuid necessary for engagement of the
The diaphragm plate I8 is provided with an
brake shoes with the brake drums has ñowed
axial cylindrical piston 25 in which is slidably
_ from the master cylinder to the brake cylinders, 55 arranged a manually operable piston 26 having
-
2,411,458
d
3
valves 5i and it, the former valve controlling the
a bore 2l therethrough for a purpose to be de
scribed. A snap ring 28 is arranged on the piston
28 and is slidable into a recess 29 formed in the
end of the `piston h5. A ring 39 is arranged
admission of air as stated while the valve 10 con
trols communication between the motor cham
bers E@ and 5l. The latter chamber is in con
stant communication with a source of lower pres
against the adjacent end of the piston 25 and
sure, for example, the intake manifold of the
vehicle engine. For this purpose, a nipple 84 is
connected to the motor casing section I4 to com
municate therewith and has its opposite end suit
in and displace fluid from the high pressure 10 ably Connected by a pipe (not shown) to the in
take manifold of the motor vehicle engine. The
chamber 83 in the cylinder Il. Such chamber
nipple 84 is provided with a check valve 85 to pre
»is connected by suitable lines 34 to the wheel
vent sudden increases in pressure in the motor
y'cylinders 35 ofthe vehicle.
chamber 5i.
' The left hand end of the piston 26 is grooved
In such prior constructions as that shown in Y
as at 38 and the inner end of such groove ter
engages a double-lipped packing cup 3l retained
around the adjacent end of the piston 26 by a
snap ring 32. The pistons 2 5 and 26 are movable
toward the right in Figure 1 to build up pressure
minates in a shoulder 39. A double-lipped pack
ing cup 40 is arranged in the groove 38 against
the shoulder 39. The left hand end of the
cylinder lil forms a low or primary pressure
chamber 52 in which is threaded a union 43, and
a line 46 connects this union to a master cylinder
'45 having a conventional piston (not shown)
therein operated by a brake pedal d6.
ao
_
Valve means are provided for controlling- pres
sures formed in the chambers 50 and 5i in the
motor on opposite sides of the pressure respon
‘sive unit. The diaphragm plate I8 (Figure l)
carries a preferably integral cylindrical extension
52 having a, chamber 53 therein communicating
2,5
the said Patent No. 2,377,699 to Klimkiewicz, fluid
displaced from the master cylinder operates a
piston such as the piston 2S to operate a valve
lever, such as the lever 76, to energize the motor
and thus utilize the power thereof for assisting
the manually operated pistons for generating
pressure in the high pressure side of the system
leading to the brake cylinders. Before such mo
tor actuation takes place, it is highly desirable
that fluid from the master cylinder first ñow
through the bore 2l to operate the brake cylin
ders 35 to engage the brake shoes with the drums.
Such operation
the brake cylinders requires
the movement of a far greater quantity of fluid
with one end of a pressure hose or other conduit 30 than is moved or displaced after initial engage
54, this hose being connected to a source of at
ment of the brake shoes takes place.
mospheric or super-atmospheric pressure de
latter point in the' operation of the mechanism
After the
is reached, pressure will be built up in the system
pending upon Wheth'er the motor is to be vacuum
and the area of the left hand end of the piston
or pressure operated. In the present instance,
the conduit 5è leads to a connection 55 commu 35 25 in the present construction being greater than
the area of the right hand end thereof, the piston
nicating with the atmosphere externally of the
26 will then move to the right to effect motor op
motor casing section I4, such space preferably be
eration. The power operation then occurring
ingcovered by a shell 55 housing a suitable air
requires the closing of the bore 2l. For this pur
cleaner 5l.
The tubular extension 52 is provided internally 40 pose, a rod 9U extends through the bore 21 to en
gage a ball 9i engageable with a. seat 92 formed
thereof with a valve seat 6G shown in the present
at the inner end of an enlarged bore 93 at the
instance as being engaged by a ball valve BI urged
right hand end of the piston 26 in Figure 1,
to closed position by a spring 62, one end of such
movement of the ball out of the bore 93 being
spring engaging the ball 5i and the other end
prevented by a pin 94. In a manner to be de
engaging a spring seat 63 which closes the adja
scribed, the rod 90 when the parts of the appa
ce'nt end of the extension 52 to communication
ratus are in the “olf” position shown in Figure 1
with the motor chamber 5i. The ball Si is
occupies the position holding the valve 9| off its
seat, and the space around the rod 90 and around
A second tubular extension 69 is preferably 50 the ball 9| when‘the latter is unseated is such as
to provide for the substantially unrestricted flow
formed integral with the diaphragm plate i8 and
oi' fluid from the master cylinder through the
has its interior communicating with the motor
bore 2l into the chamber 33 to displace there
chamber 5i through a port 59. A valve, shown
from suiiicient iiuid to engage the brake shoes
as a ball lli, is engageable with a seat ’il to con
adapted to be unseated by a stem Si operated in
a manner to be described.
trol communication between the motor chambers
59 and 5i, this valve being urged from its seat by
with the lbrake drums.
a spring 12 of lower tension than the spring t2
for a purpose to be described.
pression of the brake pedal can displace iiuid
from the master cylinder at a rate greater than
such fluid can flow directly through the appara'
tus into the brake cylinders, thus building up in
The diaphragm plate i8 is provided with lugs
‘i5 engageable with the adjacent end of :the cyl
‘inder l0 to limit movement of the pressure mov
able unit to the left as viewed in Figure v1, and a
compression spring 'i5 urges the pressure respon
sive unit in such direction. The lugs l5 and the
piston 2t are straddled by a lever it, this lever
_
In prior constructions, the sudden rapid de
the chamber d2 a false pressure suflicient to oper
ate the piston 26 to energize the motor I2 before
the brake shoes are initially engaged with the
brake drums by fluid flowing through the pas
sage 2ï, chamber 33 and brake lines 34. This
false `operation is due to the fluid friction of the
elements through which fluid flows to the brake
cylinders, and to the inertia of the brake shoes
against sudden movements. The present device
being provided with an opening 'il through which
extend the -lugs ‘l5 and the piston 26. One end
‘i3 of the lever is directly engageable with the ball
19. Centrally of its length the opposite sides of
the lever are preferably stamped to provide 70 prevents such operation. Referringto Figure 3,
the end of the piston 26 is provided with a bore
bulged points 19 engageable with a yoke Bil
99 larger than and communicating with the bore
snapped around the piston 26 and fixed against
2l into which extends a control device 99 pressed
movement to the left relative thereto by a snap
as at- lilii into the adjacent end of the union 43
ring 8l (Figurefl).
The lever 76" controls the movement of the 75 'and having a bore Iûi extending therethrough.
attacca
@il
A rubber or similar packing ring itt is carried
by the control device 99 for sliding engagement
in the bore et. The inner end of the device il@ is
Cav
provided with a slot H33 to facilitate flow of fluid
past the adjacent end of the rod 90. The end of
the piston 2t in Figure ‘.5 is spaced from the adja
cent end of the chamber ¿l2 and in this space the
device 99 is provided with a relatively restricted
metering port Hill affording limited communica
tion between "the bore lili and the chamber ¿i2
when the parts of the apparatus are in the “oiî”
A position. 'Ihe rod 90 is engaged against the ad
`iacent end of the device 99 when -the parts are
the lever will seat the valve lil. Ver; little move«
ment of the lever “iii is required for this opera»
tion since the lower end oi the lever 'will move
twice the distance of the piston
Prior to the operation referred t@ 'the motor
i2 will be “vacuum suspended,” that is, balanced
subatmospheric pressures will exist in the motor
chambers 50 and 5i. The seating of the valve
'i0 closes communication between the motor
chambers, and since the lower end of the lever
will be ñxed against further movement toward
the right, continued slight movement of the pis»
ton 26 `vill move the upper end of the lever it
in the position referred to to hold the ball ai off
to
unseat the ball tl, thus permitting air to dow
its seat. Contact between the rod 90 and the
past the valve lil into the motor chamber 5B.
device 99 is established when the brake parts
The higher pressure thus established in the mo~
reach the fully released position, and when the
tor chamber till will effect movement of the pres~
brakes are applied, brake fluid flowing through
sure
movable unit it toward the right t0 sirn
the bore lll! readily moves the end oi’ the rod
til toward the right as viewed in Figure 3 for the 20 iîarly move the piston 25. If the movement oi
the piston 2li stops, a very slight additional moven
free ñow of fluid from the bore lill into the
ment of the pressure movable unit l@ will release
bore 2l.
the
pressure of the upper end of the lever from
The operation of the mechanism is as fol»
the pin @t and the motor operation also will stop.
Any tendency for the pressure movable unit to
lows:
>vAssuizning thatA the brakes are completely
re
move too far will result in “cracking” the vac
leased with the parts in the positions shown in
uum valve 'it to exhaust some of the air from
the drawings, brake application will take place
the motor` chamber 50 to establish the proper
upon operation of the pedal ¿36. Such operation
differential` motor Ipressures to arrest operation
displaces fluid from the master cylinder (it
of ,the motor. It wm be obvious that the pressure
through the line riß, bore lill (Fig. 3) and bore 30 movable unit i 6 partakes of a follow-up action
21 into the high pressure chamber 33 (Fig. 1) to
with respect to the piston ‘26.
displace fluid therefrom to move the brake shoes
It will be apparent that movement oi the pis
into engagement with the brake drums. The
ton
26 toward the right through a relatively short
iiow of fluid referred to is relatively unrestricted,
distance will carry the valve seat S32 into engage»
Whereas there is substantial restriction in the
ment with the ball di, the rod tl thus becoming
flow of fluid through the metering port lllál (Fig.
ineffective
for holding the ball tl ofi its seat.
3). The ñow of huid thus displaced from the
The chamber ¿it thus will be disconnected from
master cylinder will result in a positive flow of
the chamber t2, and movement of the pistons
a much greater volume of fluid through the bore
2l than through the port lûli, the latter flow 40 25 and 2t will displace huid from the chamber
33 into the brake lines to provide the necessary
being insuflicient to cause rapid movement of the
braking pressures, these pressures being built up
piston 26. The flow of i‘luid through port imi will
partly by manual operation of the piston tt and
result in very slow movement of the piston 2t
partly
by power operation of the piston ‘25. The
through which motor energization is effected.
operator thus performs part of the work in build
The relatively unrestricted i‘low of fluid through
ing up the braking pressures and the foot pedal
bore 27 causes positive engagement of the brake
te is always subjected to reaction pressures
shoes with the brake_ drums before substantial
exactly
proportional to the braking pressures. .
operation of the piston 26 occurs. and ‘con
Assuming that` the movement of huid through
sequently before any substantial operation oi the
tb line (ifi at the beginning of the brake oper
motor l2 takes place, the latter operation being
ation will have taken place incident to a very
referred to below.
rapid brake pedal operation, the iiow of fluid
Whether any motor energization taires place ’
through the port Hifi may result in sufñcient
prior to initial engagement of the brake shoes
movement of the piston 26 to cause energization
with the brake drums depends upon the rate of
of the motor. However, the movement of the
displacement of iluid from the master cylinder
piston te necessarily will be relatively slow, and
t5. Assuming that the flow capacity of the bore
the packing db2 is arranged a sufñcient distance
2l is sufficient under a given ,operating condi
from the left hand extremity of the piston tti
Ätion to engage the brake shoes with the drums
to insure motor operation at a very slow rate to
prior to motor energization, contact of the shoes
with the drums will be immediately followed by 60 insure the taking up oi' play between the brake
shoes and drums prior to the point at which the
an increase in pressure in the entire hydraulic
left hand extremity of the piston 2S passes the
system. The pressure increase will result in a
packing H32. From this point on, the bore lili
more rapid now of iiuid through the port itil
will provide for the relatively unrestricted ilow
which will be followed by a more rapid move
oi” fluid into the chamber d2, By this time, how
ment of the piston 2li.
' ever, the brake shoes will have ~been deñnitely
brought into engagement with the brake drums. _
from
Anyitssubstantial
normal or movement,
“off” position
of the
will piston
result in
When the foot pedal iid is released, pressure
operating the valve mechanism to energize'the
will drop in the chamber ¿i2 and. the pressure
motor it. The engagement oi.’ the member t@
acting against the opposite endvor‘ the piston t6
(Figures l and 2) with the points ‘iii of the lever 70 will move this piston toward the left (Fig. l) to
’I6 will tend to cause bodily movement of this
release the pressure exerted against the valves
lever toward the right. The spring G2 being of
iii and lll. 'I‘he closing of the valve tl will cut
y greater tension than the relatively weak spring
ofi the chamber 50 from the atmosphere and the
l2, the lever 'i6 will íulcrum at its point of en
opening of the valve 'ill will connect the cham
gagement with the pin
and the lower end of 75 bers il!) and 5l for the exhaustion oi air from
2,411,458
the chamber 50. The spring 16 will return the
parts to their normal positions, and when the
rod 90 engages the device 99, the ball 9| will be
unseated to reestablish the communication be
tween the line 44 and the brake cylinders. The
unseating of the valve 9| when the parts are in
the normal or “off” positions provides for the
flow of fluid through the bore 2l when brake
pedal operation is initiated, as stated. The un
8
member is in its “0E” position, meansv for pre
venting such flow of fluid after said pressure re
sponsive member has moved a predetermined dis
tance and the pressure in said high pressure cyl
inder is higher than the pressure in said low pres
sure cylinder, and means co-operating with said
pressure responsive member and dependent there
on when the latter is in its “off” position for lim
iting the flow of fluid from the master cylinder
seating of the ball 9| also permits the replenish 10 into said low pressure cylinder relative to the
flow of fluid from the master cylinder to said
ing inthe high pressure side of the system of any
high pressure cylinder when the master cylinder
leakage of brake fluid which may have occurred,
is initially actuated.
and the usual valve (not shown) at the outlet
2. In a booster mechanism for a hydraulic 've
of the master cylinder 45 will maintain the usual
15 hicle brake system having wheel cylinders to ap
residual pressure throughout the system.
ply the brakes and a pedal-controlled master
It will be apparent that the use of the mecha
cylinder, a booster unit comprising a low pres
-nism shown in Fig. 3 positively limits the flow of
sure cylinder adapted to communicatewith the
fluid into the chamber 42 to thus limit motor-4
master cylinder, a high pressurehcylinder adapted
energizing operation of the piston 26 until the
brake shoes have been engaged with the drums. 20 to communicate with the wheel cylinders, a mio-_. ,
Without such means, sudden rapid brake pedal
tor having a movable unit including a member-
operation may result in the relatively excessive
projecting into said high pressure cylinder to
flow of fluid into the chamber 42 thus building
up a false pressure therein. Such false pressure
vdisplace fluid into said wheel cylinders upon en
ergization of said motor, a pressure responsive
in the chamber 42 would cause a motor-energiz
ing movement of the piston 26 and such move
ment of this piston not only will energize the
motor but will resultin the closing of the valve
9| before the brake shoes have been engaged with
the drums.
25 member in said low pressure cylinder operable
by fluid displaced from the master cylinder, means
operable bysaid pressure responsive member for
energizing said motor, said booster unit being
constructed to provide for the substantially unre
Under such conditions, all of the 30 lstricted flow of fluid from the master cylinder
to said high pressure cylinder when said pressure
remaining fluid necessary for initial engagement
ofthe brake shoes would have to be supplied
solely from the chamber 33 and this could take
place only by movement of the pistons 25 and
26.
Unless the high pressure cylinders of prior
devices are made relatively long, therefore, it is
possible for the piston elements moving into the
high pressure chamber to reach their limits of
movement prior to a full brake application. To
insure the proper operation of Vsuch a mechanism
under all conditions, therefore, it is necessary
as a practical matten-to make the pressure cyl
inders, corresponding to the cylinder ||, rela
tively long.' Such construction obviously is not
necessary in the present device. Therefore, the
present device permits the shortening and com
pacting of the mechanism and further insures
the performance of the intended booster opera
tion of the apparatus. _
responsive member is in its “off” position, means
for preventing such flow of fluid after said pres
sure responsive member has vmoved a predeter
- mined distance and the pressure in said high
- pressure cylinder is higher than the pressure in
said low pressure cylinder, and a device mounted
in said low pressure cylinder and communicating
with the master cylinder, such device having a
40 port communicating at all times with said low
pressure cylinder and of such cross sectional area
as to positively limit the flow 'of fluid from the
master cylinder into said low pressure cylinder
relative to the flow of fluid from the master
45 cylinder to said high pressure cylinder when said
_ pressure responsive member is in its “oiî” posi
» tion, .said device having a passage normally closed
to said low pressure cylinder by said pressure re
sponsive member when the latter is in its “off”
50 position and opened to said low pressure cylinder
It is to be understood that the form of the in
by movement of said pressure responsive member
vention herewith., shown and described is to be
from its “off” position.
taken as a preferred 'example of the same and
3. In a booster mechanism for a hydraulic ve
that various changes in the shape, size and ar
hicle brake system having wheel cylinders to ap
rangement of parts may be resorted to without
departing from the spirit ofthe invention or the 55 ply the brakes and a pedal-controlled master
cylinder, a booster unit comprising a low pres
scope of the subjoined claims.
sure cylinder and a high pressure cylinder ar
I claim:
ranged in axial alinement and’adapted to com
l. In a booster mechanism for a hydraulic ve
municate respectively with the master cylinder
hicle brake system having wheel cylinders to'ap
ply the brakes and a pedal-controlled master cyl 60 and with the wheel cylinders, a differential fluid
pressure motor having a pressure responsive unit
inder, a booster unit comprising a low pressure
and a member carried thereby and projecting into
cylinder adapted to communicate with the master
said high pressure cylinder to displace fluid
cylinder, a high pressure cylinder adapted to
therefrom upon energization of said motor, a pis
communicate with the wheel cylinders, a motor
having a movable unit including a member pro 65 ton in said’low pressure cylinder movable by fluid
displaced from the master cylinder, a valve mech
i jecting into said high pressure cylinder to displace
fluid into said wheel cylinders upon energization
anism operable by said piston for energizing said
motor, said booster unit being constructed and
of’said motor, a pressure responsive member in
arranged to utilize the pressure generated in the
said low pressure cylinder operable by fluid dis-placed from the master cylinder, means operable _ 70 master cylinder for assisting said motor in gen
erating pressures in said high pressure cylinder,
by said pressure responsive member for energizing
and being further constructed and arranged to
said motor, said booster unit being constructed
to provide for the substantially unrestricted flow
of fluid from the master cylinder to saidhigh
provide for the substantially unrestricted flow of '
fluid from the master cylinder, and to said high
pressurel cylinder when said-pressure responsive 75 pressure cylinder when said piston is in its ."off"
2,411,458
10
position, means for preventing the flow of fluid
from the master cylinder to the high pressure cyl
inder after said piston has moved a predetermined
distance-from its "off” position and when pres
sure in said high pressure cylinder is higher than
in said low pressure cylinder, and metering means
from upon energization of said motor, a pres
sure responsive device movable >by fluid entering
said low pressure chamber, said booster mecha
nism being constructed and arranged to provide
for relatively unrestricted flow of fluid from the
fluid displacing device to said high pressure
chamber when said pressure responsive device
is in its “off” position, means operative for stop
co-operating with said piston and dependent
thereon when the latter is in its “off” position for
positively restricting the flow of fluid from the
ping said ?low of fluid after said pressure re
master cylinder to said low pressure cylinder when 10 sponsive device has been moved and pressure in
said master cylinder is initially actuated.
i
said high pressure chamber is higher than in .
4. Apparatus constructed in accordance with
claim 3 wherein said metering means comprises
a metering device mounted in said low pressure
chamber, such metering device having a bore
therethrough communicating with the master cyl
inder and through which passes the iluid which
said low pressure chamber, and means co-oper
ating with said pressure responsive device and
dependent thereon when the latter is in its “oil”
position for positively limiting the now of fluid
from the fluid displacing de_vice into said low
pressure chamber relative to said flow of iluid to
ilows from a master cylinder to said high pres
‘
said high pressure chamber when said. fluid dis
sure cylinder, said metering device having a rela
placing device is initially actuated.
tively restricted passage communicatying at all 20
8. A hydraulic booster unit comprising a low
times between said bore and said low pressure
pressure chamber adapted for connection with a
cylinder.
hydraulic iluid displacing device,- a high pres
5. In a booster mechanism for a hydraulic
sure chamber adapted for connection with a
device to be hydraulically operated, a motor
vehicle brake system having wheel cylinders for
applying the brakes and a pedal-controlled
master cylinder, a booster unit comprising a low
pressure cylinder and a high pressure cylinder
arranged in axial allnement and communicating
2.5 having a fluid displacing element movable into
said high pressure chamber to displace fluid
„ therefrom upon energization of said motor, a
pressure responsive device movable by ñuid
entering said low pressure chamber, -sald booster
mechanism being constructed and arranged to
provide for relatively unrestricted ñow o1' fluid
from the fluid displacing device to said high
pressure chamber when said pressure responsive
device is in its “off” position, means operative for
respectively with the master cylinder and with
the wheel cylinders, a differentiaI iluid pressure
motor having a pressure responsive unit, a ñuid
displacing piston carried by said unit and pro
jecting into said high pressure chamber to dis
place fluid therefrom upon energization of said
motor, a control piston having one end arranged
closing communication between the ñuid- displac
ing device and said high pressure chamber after
in said low pressure cylinder and its opposite end
projecting through said nuid displacing piston
said pressure responsive device has been moved
and pressure in said high pressure chamber is
to displace fluid from said high pressure cham
ber, a follow-up control valve mechanism for
said motor operable by said control piston and by
said pressure responsive unit, said control piston
having a bore therethrough to provide for the
substantially unrestricted iiow of fluid from the
master cylinder to said high pressure cylinder,
40
means for closing said bore upon'a predeter- '
mined movement of said controlpiston from its
device is actuated.
“off” position and when the pressure in said >
high pressure cylinder is higher than in said low
pressure cylinder, and a metering device for
limiting the flow of fluid into said low pressure
cylinder relative to the ñow of fluid through
said bore when the master cylinder is initially
actuated.
>
higher than in said low pressure chamber, and a
device projecting into proximity to said pressure
responsive device when the latter is in its “off”
position and dependent thereon for positively
limiting the flow of fluid into said lowl pressure
chamber relative to said ñow of fluid into said
high pressure chamber when said fluid displacing
.
9. A hydraulic pressure booster mechanism
comprising a low pressure chamber and a high
pressure chamber in axial alinement and adapt
ed for communication respectively with a hy
draulic fluid displacing device and a device to
be actuated by hydraulic fluid, a diil‘erential duid
pressure vmotor having a pressure responsive
_structure including a member projecting into
said high pressure chamber to displace fluid
.
6. Apparatus constructed in accordance with
claim 5 wherein said metering device comprises
a stationary member mounted in said low- pres
sure cylinder and having a bore therethrough
directly communicating with the bore in said
therefrom, a pressure responsive member mov
able by fluid entering said low pressure cham
ber, a control valve mechanism operable by said
control piston to supply ñuid thereto directly
pressure responsive member to energize said
from the master cylinder, said metering device 60
motor, said pressure responsive member extend-projecting into the adjacent end of said control
ing through said fluid displacing member into
piston when the latter is in its “off” position and
said
high pressure chamber to displace fluid
being provided with a relatively restricted port
therefrom and being provided throughout its
communicating at all times with said low pres
length with a bore providing for substantially
sure chamber, the cross sectional area of said
unrestricted
now ot fluid therethrough into said
port being smaller than the cross sectional areas
high pressure chamber, means for closing said
of the bore of said control piston and said meter
ing device.
bore upon a predetermined movement of said
4
pressure responsive member when pressure is
7, A hydraulic booster unit comprising açlow
higher
in said high pressure chamber than in
pressure chamber adapted for connection with 70
said low pressure chamber, and means for re
a hydraulic iiuid displacing'device, a high pres
stricting the flow of fluid from said pressure
sure chamber adapted for connection with a de
l
vice to be hydraulically operated. a motor hav
ing a iluid displacing element movable into said
high pressure chamber to displace fluid there 75
displacing device into said low pressure cham
ber relative to the flow of fluid through said bore
when said fluid displacing device is initially
actuated.
2,411,458
11
10. Apparatus constructed in accordance with
claim 9 wherein said last named means com
prises a device mounted in said low pressure
ing an axial bore therethrough lfor the unre
stricted ñow of fluid to said high pressure cylin- .
der, a check valve for said bore seating away
from said high pressure cylinder, a rod in said
bore, a metering device arranged in said low
pressure cylinder and having an axial passage
communicating with the master cylinder, one
end of such device extending into one end of
said bore to deliver ñuid directly from said pas
10 sage to said bore, said metering device having a
said low pressure chamber.
i
11; In a .booster mechanism for a hydraulic
relatively restricted port in constant communi
vehicle brake system having wheel cylinders for
cation between said passage and said low pres
applying the brakes and a pedal-controlled
sure cylinder, one end of said rod being engage
master cylinder, a booster unit comprising a low
able with said metering device to unseat said
pressure cylinder and a high pressure cylinder 15 check valve when said control piston is in its
arranged in axial alinement and adapted to com
“oil” position.
.
municate respectively with. the master cylin er
12. Apparatus constructed in accordance with
and with the wheel cylinders, a differential ñ d
claim 11 wherein the end of said bore in which
pressure motor having a pressure responsive unit,
said end of said metering device projects is ot '
a tubular piston connected to such unit and pro 20 larger diameter than said metering device, and
.jecting into said high pressure chamber to dis
wherein a sealing ring is interposed between said
place fluid therefrom upon energization of said
metering device and the enlarged end of said
motor, a control piston having one end arranged
bore to prevent the flow of iluid from said pas
in said low pressure cylinder and its opposite end
sage through the enlarged end of said bore into
projecting through said tubular piston to dis 25 said low pressure cylinder untilasaid control pis
place iluid from said high pressure chamber, a v ton has moved a predetermined distance _from
follow-up control valve mechanism i'or said mo
its “oiT' position.
chamber and projecting into the adjacent end
of said bore, such device being provided with a
substantially unrestricted passage communicat
ing between said fluid displacing device and said
bore,- and with a relatively restricted port com~municting at all times between said passage and
tor operable by said control piston and by said
pressure responsive unit, said control piston hav
WILLIAM F. PENROSE.
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