Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1144~38
A-421 SCHNELZER
This invention relates to vacu~ break devices or
reciprocating vacuum motors for controlling carburetors on
internal combustion engines, and more particularly to such
devices in which the length of stroke can be controlled.
Vacuum break devices which are used with carburetor
control devices are typically provided with an adjusting
arrangement by which the length of stroke of the device can be
set at the time that the engine receives its final tuneup
during manufacture.
Usually, the vacuum break device operates at the
same adjustment throughout the lifetime of the vehicle. It has
been found, however, that when the vacuum break devices are
adjusted, for some predetermined condition at the time the
automobile is manufactured, that over a period of time the
engine operating conditions change sufficiently so that the
length of stroke of the vacuum break device should be readjust-
ed to modify the choke control in order to avoid excessive and
undesirable emissions. Usually, such an adjustment requires
a slight lengthening of the stroke of the vacuum break device
so that the carburetor choke valve is moved an additional few
degrees of arc toward a more open position to make the air fuel
mixture leaner. It is desirable that such an adjustment occurs
automatically, and also that the adjustment be of some pre-
determined amount to avoid errors such as those that might
occur by making manual adjustments and which could result in
excessive emissions.
With such devices which must operate to achieve their
purpose infrequently, it is desirable that the arrangement can
be operated to test its condition, and also that relatively
30 --movable parts are cycle~ frequently to insure that relatively
movable parts will be operable at the time that their function
is needed. _ -
~
--1--
A-421 SCHMELZER
With this in mind, it is an object of the invention
to provide a recipxocating vacuum break device or vacuum motor
for carburetors of internal combustion engines in which the
length of stroke can be automatically varied in response to a
control signal.
Another object of the invention is to provide such a
vacuum break device wherein relatively movable parts required
to carry out a function relatively infrequently are moved
relative to each other frequently during the course of usual
operations so that they are freely movable relative to each
other at the time that their function is required.
A vacuum motor or vacuum break device for carbure-
tors is provided which operates in two stages and in which a
housing has a pair of movable walls dividing the housing into
a control chamber between the two walls and an actuating cham-
ber to one side of the control chamber with the chambers being
isolated from each other. ~n output member is connected to
one of the movable walls and projects from the housing for
connection through linkage to controls on a carburetor such as
a choke valve so that the choke valve is moved in response to
movement of the movable walls and housing. The movable walls
are connected to each other to determine both their minimum
and maximum spacing. Vacuum is supplied to the control cham-
ber to determine the minimum spacing of the movable walls and
the supply of vacuum to the actuating chamber causes movement
of the movable walls as a unit with each other in either the
maximum spaced or minimum spaced positions relative to each
other. As a result the OUtpllt member and therefore the con-
nected carburetor control are moved a minim~n distance when
vacuum is supplied onl~ to the actuating chamber and are moved
3~
A-421 SCHMELZER
a maximum distance when vacuum is supplied to both the
actuating chamber and the control chamber.
These and other objects of the invention will be
apparent from the following description and from the drawings
in which:
Figure 1 shows a vacuum control motor in relation
to an engine manifold and a carburetor;
Figure 2 is a cross sectional view at an enlarged
scale of the vacuum motor seen in Figure l;
Figure 3 is a cross sectional view ~imilar to Figure
2 showing another mode of operation; and-
Figure 4 is a view similar to Figures 2 and 3 showing
still another mode of operation of the motor.
Referring to the drawings, the vacuum break device
embodying the invention is desiynated generally at 10 and is
adapted to be supported relative to a carburetor 12 of an
internal combustion engine. The vacuum break device 10 in-
cludes a housing 16 from which a plunger assembly 18 pro~ects.
The plunger assembly 18 includes a slot 20 adapted to receive
the end of a crank 22 connected through linkage 23 for moving
a choke valve 24 from its normally closed position shown in
the drawing to an open position.
The housing 16 of the vacuum break device 10 includes
a front housing cover 26 and a rear housing cover 28 which are
separated by an annular spacer ring 30. Preferably the front
cover member 26 is stamped of metal and the center spacer ring
30 and rear cover 28 are molded of plastic material.
Disposed ~ithin the housing 16 is a forward diaphragm
asse~bly 32 including a diaphra~n 34 and a rearward diaphragm
assembly 36 including a diaphragm 38. The diaphragms 34 and 36
3~3
are clamped to opposed faces of the spacer ring 30 by the
front and rear covers 26 and 28 which are held in assembled
conditivn by a clamping ring 40 folded over the spacer ring 30
and the peripheral flanges of the covers 26 and 28. Diaphragm
34 and 38 divide the interior of the housing into a forward
chamber 42, an intermediate chamber 44, and a rear chamber 46
which are isolated from each other.
The rear cover member 28 of the housing 16 has an
axailly disposed adjusting screw 50 supported in the wall of
the cover 28 of the vacuum break 10. The adjusting screw 50
is threaded in the rear cover 28 and is suppor-ted in complemen-
tary threads so that a head 56 is available at the exterior
of the housing 16 and an end 57 of the screw 54 is disposed
within the chamber 46 in the interior of the housing 16 for
engagement with the diaphragm assembly 36 upon movement -to the
right as viewed in Figure 1.
The forward diaphragm assembly 32 includes opposed
backing plates 58 and 60 which are disposed at opposite sides
of the forward diaphragm 34 and are held together by a rivet
portion 62 at one end of the output plunger 18. The rearward
diaphragm assembly 36 includes backing plate~ 66 and 68 which
are fused together by an adhesive or sonic welding or the
like, to hold the backing plates 66 and 68 in fluid tight
relationship with the diaphragm 38.
The diaphragm assembly 32 and 36 form moveable walls
and are connected together for limited relative movement by
means of a male connector 70 formed integrally with the backing
plate 66 and a complementary female connector 72 having an
annular fing 74 held in fixed position relati.ve to backing
platc 60 and an annular groove indicated at 78. The male
--4--
11~4438
A-421 SCHMELZER
connector 70 is formed by a plurality of fingers 76 having
notches 78 which recei~e an annular flange 80 of the female
connector 72. The notches 78 and the annular lip or flange 80
are so dimensioned that a limitedamount of telescoping of con-
nectors 70 and 72 is permitted to provi~e limited axial move-
ment between the diaphragm assemblies 32 and 36.
A spring 82 is disposed between the annular ring 74
on the diaphragm 32 and the backing plate 66 on the diaphragm
36 to urge the diaphragm assemblies 32 and 36 apart from each
other. A spring 84 also is disposed between the backing
plate 68 and an interior wall of the cover member 28 to bias
the diaphragm assembly 36 to the left as viewed in Figure 2.
The spring 84 is stronger than spring 82 so that both diaphragm
assemblies are at their extreme left position under nonoperat-
ing conditions.
Vacuum pressure is made available to the chamber 46by way of a vacuum inlet tube 86 formed in cover 28 and com-
municating by way of a hose 88 with an intake manifold 89
indicated in Figure 1. Vacuum pressure also is made available
to the intermediate chamber 44 by means of a ~acuum inlet tube
92 communicating through a tube 94 with the intake manifold 89.
A control valve 96 is disposed in the tube 94 for controlling
communication from the vacuum pressure to the chamber 44. The
forward chamber 42 is in continuous communication with the
atmosphere by way of an opening 98 in the forward cover 26
through which the plunger assembly 18 pro~ects.
In the absence of vacuum pressure such as would
occur when the internal combustion engine is not operating, all
; of the chambers 42, 44 and 46 are under atmospheric pressure,
and the position of the diaphragm assemblies 32 and 36 is
--5--
38
determined by springs 82 and 84. The diaphragm assembly 32
occupies the position seen in Figure 2 with the backing plate
58 against the internal wall of the housing cover 26. The
diaphragm assemlby 36 will be positioned with backing plate 66
against flange 80 due to the action of the strong spring 84
which overcomes the spring 82.
When the internal combustion engine is started, a
source of vacuum pressure is established in the manifold 89 and
a differential pressure is created across the diaphragm assemb-
ly 36 by the establishing of vacuum pressure in the ch;amber 46.
The differential pressure across the diaphragm assembly 36
resulting from the atmospheric pressure in the chamber 44 and
the vacuum pressure in chamber 46 causes the diaphragm assembly
36 to move to the right. In the init.l:al portion of that move-
ment, the diaphragm assembly 32 remains stationary and the
annular flange 80 will move to the left end of the notches 78
to the position illustrated in Fiyure 3. During such initial
movement, plunger 18 remains stationary. When the end of the
notches 78 engage the annular flange 80, further movement of
the diaphragm assembly 36 against the biasing action of the
spring 84 is effective to pull the diaphragm assemlby 32 and
the output plunger 18 to the right as viewed in Figure 3 until
the backing plate 68 of the diaphragm assembly 36 comes into
engagement with the end 57 of the adjusting screw 50. The
total range of movement of the output member 18 is equal to
the distance between the screw end 57 and the backing plate 68
as vlewed in Figure 2 reduced by the space of notch 78 occupied
by flange 80.
During normal or initial operation of the control
device 10, the control valve 96 can be maintained to isolate
the chamber 44 from the intake manifold 89 and to maintain the
--6--
;3~
chamber 44 at atmospheriG pressure. The control valve 96 can
be made to respond to various conditions such as temperature to
cause the chamber 44 to be placed in communication with the
source of vacuum or manifold 89 after some predetermined engine
temperature is achieved. Also, if desired, -the valve 96 can
be made to respond to the odometer drive of a vehicle so that
it opens after a predetermined number of miles. The valve 96
alternatively can be made responsive to an engine hour meter
so that the valve opens after some predetermined number of
engine hours have been experienced.
After the engine has been opera-ted to achieve the
control condition, valve 96 opens and vacuum pressure is made
available not only in the chamber 46 but also in the chamber
44. Under such conditions the pressure in chambers 44 and 46
is equal but a pressure differential is created across the
diaphragm assembly 32 due to atmospheric pressure in the
chamber 42. Since -the starting position of the vacuum motor is
with the annular flange 80 a-t the right end oF -the groove 78
the diaphragm assembly 32 and 36 to the righ-t until the backing
plate 6B on diaphragm assembly 36 engages wi-th the end of the
screw 50. At tha-t time, movement of the diaphragm assemblies
32 and 38 stops and the diaphragm assemblies remain at their
minimum spacing, -that is with the annular flange 80 a-t the
right end of the grooves 78 as viewed in Figure 4. Under
these conditions of operation, -the output plunger 18 is moved
an additional amount comparecL with its movement when vacuum
pressure is made available only in the chamber 46. The addition-
al amount of movement of the plunger 18 is equal -to the length
of the notches 78 less the thickness of the annular flange 80,
or the distance that flange 80 can travel in or the notches 78.
When operation of the engine is s-topped, vacuum
pressure is no longer available at the intake manifold 89 and
the chambers 44 and 46 return to atmospheric pressure permit-
ting the return springs 82 and 84 to urge both of the diaphragm
assemblies 32 and 36 to their e~treme left position as seen in
Figure 2 at which they are at their minimum spacing. It
will be understood that the amount of the increase in the
length of stroke can be varied by cnanging the relative dimen-
sions of either the flange 80 or the notches 78. In actual
practice with a vacuum control d.evice 10 it was found useful
to increase the length of stroke of the outpu-t member 18 by
only a small amount sufficient to open the choke valve 24 an
additional few degrees to make it possible to provide a leaner
fuel air mi~ture. The change in adjustment can be obtained
automatically in response to operation of the control valve 96.
From this it can be seen that -the control motor has
one type of operation initially when vacuum is supplied only to
the chamber 46 and still a different type of operation when
vacuum is supplied -to both the chambers 44 and 46 after the
control valve 96 has been actuated in response to some pre-
determined condi-tion such as temperature, engine hours, or
vehicle miles. Nevertheless, even in the early stages of
operation when vacuum is not made available at the intermediate
chamber 44, the various par-ts move relative to each other each
time that the engine is started and stopped. In other words,
tlle diaphragm assemblies 36 and 32 move relative to each other
a small amount as de-termined by the amount of movement of the
annular flange 80 in the notches 78. Also, both diaphragms
--8--
~149~38
A-421 SCHMELZER
move initially relative to each other and subsequently as a
unit, and return to their original positions a~ter the engine
has stopped. Similarly after the control valve 96 has been
moved to its open position and vacuum is supplied to both of
the chambers 44 and 46, the diaphragm assembly 32 and 36
initially move relative to each other and subsequently move
as a unit to maintain their minimum spacing in which the annu-
lar flange 80 is disposed at the right end of the notches 78
as viewed in Figure 2.
Although the length of stroke of the stem 82 of the
plunger assembly 18 can be changed automatically after some
predetermined time, it will be noted that it is possible for a
mechanic to make any necessary adjustments by use of the adjust-
ing device 50. The operation of the adjusting device 50 is
available independently of whether or not the vacuum break 10
is operating in its initial phase or in its final phase.
A vacuum break 10 for carburetors of internal com-
bustion engines has been provided having two modes of operation.
In the first mode the reciprocating vacuum break motor has a
stroke of a given length for opening the choke of a carburetor
some predetermined amount and in the second mode of operation
which can be obtained after the engine has been operated some
predetermined period of time, or achieves a predetermined tem-
; perature, the vacuum break has another length of stroke which
is longer so that the carburetor choke is moved to a more open
position to obtain a leaner carburetor setting.
