U.S. patent application number 14/605024 was filed with the patent office on 2015-08-20 for super aspirator with integrated dual flow shut off.
The applicant listed for this patent is Nyloncraft, Inc.. Invention is credited to Amy Backhus, Matthew Burnham.
Application Number | 20150233393 14/605024 |
Document ID | / |
Family ID | 53797707 |
Filed Date | 2015-08-20 |
United States Patent
Application |
20150233393 |
Kind Code |
A1 |
Burnham; Matthew ; et
al. |
August 20, 2015 |
SUPER ASPIRATOR WITH INTEGRATED DUAL FLOW SHUT OFF
Abstract
In one embodiment, an aspirator is provided including a venturi
pipe having a converging section including a converging inlet and a
converging outlet, and a diverging section having a diverging inlet
and a diverging outlet. The converging outlet is in fluid
communication with the diverging inlet. A throat is positioned
between the converging outlet and the diverging inlet. A shut off
valve is movable between an open position and a closed position.
The shut off valve is positioned within the throat when in the
closed position.
Inventors: |
Burnham; Matthew; (Allen
Park, MI) ; Backhus; Amy; (Granger, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nyloncraft, Inc. |
Mishawaka |
IN |
US |
|
|
Family ID: |
53797707 |
Appl. No.: |
14/605024 |
Filed: |
January 26, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61940643 |
Feb 17, 2014 |
|
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Current U.S.
Class: |
417/189 |
Current CPC
Class: |
F04F 5/20 20130101; F04F
5/42 20130101; F04F 5/46 20130101 |
International
Class: |
F04F 5/42 20060101
F04F005/42 |
Claims
1. An aspirator comprising: a venturi pipe having a converging
section including a converging inlet and a converging outlet, and a
diverging section having a diverging inlet and a diverging outlet,
the converging outlet in fluid communication with the diverging
inlet; a throat positioned between the converging outlet and the
diverging inlet; a shut off valve movable between an open position
and a closed position, the shut off valve positioned within the
throat when in the closed position.
2. The aspirator of claim 1, wherein the shut off valve has an
aperture extending therethrough, wherein, in the closed position,
the aperture is in fluid communication between converging outlet
and the diverging inlet.
3. The aspirator of claim 2, wherein the aperture has an upstream
end position adjacent the converging outlet, the upstream end
having a diameter that is approximately the same as a diameter of
the converging outlet.
4. The aspirator of claim 2, wherein the aperture has a downstream
end positioned adjacent the diverging inlet, the downstream end
having a diameter that is less than a diameter of the diverging
inlet.
5. The aspirator of claim 2, wherein the aperture converges from
the converging outlet to the diverging inlet.
6. The aspirator of claim 2, wherein, in the open position, a first
volume of air flows from the converging outlet to the diverging
inlet, and in the closed position, a second volume of air flows
from the converging outlet to the diverging inlet, the first volume
of air being greater than the second volume of air.
7. The aspirator of claim 2, wherein air leaks trough the aperture
when the shut off valve is in the closed position.
8. The aspirator of claim 2, wherein, in the open position, air
flows from the converging outlet to the diverging inlet at a first
flow rate, and in the closed position, air flows from the
converging outlet to the diverging inlet at a second flow rate, the
second flow rate being less than the first flow rate.
9. The aspirator of claim 1, wherein the shut off valve is moved
between the open position and the closed position by a
solenoid.
10. The aspirator of claim 9, wherein the solenoid includes bumpers
that reduce noise when the shut off valve moves between the open
position and closed position.
11. An aspirator comprising: a valve body having a first air inlet
port; an air outlet port in air flow communication with the first
air inlet port to define an air passageway; a second air inlet port
in air flow communication with the first air inlet port and the air
outlet port wherein air is drawn from the second air inlet port
towards the air outlet port; a valve positioned between the air
passageway and the second air inlet port for inhibiting air flow
from the air passageway through the second air inlet port, wherein
the air passageway includes a venturi conduit positioned between
the first air inlet port and the outlet port, the venturi conduit
constituting means for enhancing air flow through the outlet port
with a corresponding enhancement of air drawn from the second air
inlet port towards the outlet port, the valve including a valve
seat positioned between the first and second inlet ports having an
opening communicating with the air passageway; a flexible seal
means positioned in the valve seat for responding to air exiting
the second air inlet port under outside vacuum influence and for
seating against the valve seat to prevent air flow from the air
passageway from exiting through the second air inlet port, the
venturi conduit positioned immediately adjacent the valve seat
opening to provide maximum vacuum boost through the valve seat; and
a shut off valve movable between an open position and a closed
position, the shut off valve positioned within the venturi conduit
when in the closed position.
12. The aspirator of claim 11 further comprising a third air inlet
port in air flow communication with the second air inlet port to
define a second air passageway in the valve body, the valve means
positioned between the first-mentioned air passageway and the
second air passageway.
13. The aspirator of claim 12 wherein the valve means includes
first and second spaced valve seats, each valve seat including a
flexible seal means positioned in the valve seat for responding to
air exiting one of the second and third air inlet ports under
outside vacuum influence and for seating against its associated
valve seat to prevent air flow from the first-mentioned passageway
from exiting through its respective second and third air inlet
ports.
14. The aspirator of claim 13 wherein the venturi conduit has a
tapered central portion of narrowed diameter immediately adjacent
the valve seat opening.
15. The aspirator of claim 11 further comprising a check valve
positioned within the valve seat, the check valve having a
scalloped diaphragm.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Ser. No.
61/940,643, filed Feb. 17, 2014 and having the title "SUPER
ASPIRATOR WITH INTEGRATED DUAL FLOW SHUT OFF," which is herein
incorporated by reference in its entirety.
BACKGROUND OF THE DISCLOSED EMBODIMENTS
[0002] Internal combustion engines have long employed air flow
conduits to provide vacuum assist for automobile subsystems, such
as brakes, automatic transmissions and others. These systems often
employ check valves located along the air flow conduit to prevent
subsystem back pressure from reaching the engine.
[0003] A check valve unit comprises an inlet and an outlet
connected to each other via a main air channel. In the assembled
state or in case of utilization, the inlet is connected to the
operating system and the outlet to the suction system. A first
check valve is located in the main air channel. This prevents the
negative pressure from escaping once it has been produced in the
operating system in case that pressure rises in the suction system.
Furthermore, one single outlet channel which branches off from the
main air channel downstream of the first check valve and lets out
into the atmosphere is provided with the check valve unit. A
venturi pipe or a narrowing of the cross-section is provided in
this outside channel. This narrowing of the cross-section is
connected via a channel, hereinafter the venturi channel, to the
main air channel at a point located upstream of the first check
valve.
[0004] In the known check valve units, it is a disadvantage that
air is constantly sucked in through the outside channel. This is
especially detrimental with combustion engines where the air mass
flowing through the choke valve of the air suction pipe is used for
engine control or to optimize the combustion process. The outside
channel containing the venturi pipe can be closed off by a sliding
valve when the system pressure of the operating system has reached
its target value.
SUMMARY OF THE DISCLOSED EMBODIMENTS
[0005] In one embodiment an aspirator is provided including a
venturi pipe having a converging section including a converging
inlet and a converging outlet, and a diverging section having a
diverging inlet and a diverging outlet. The converging outlet is in
fluid communication with the diverging inlet. A shut off valve is
movable between an open position and a closed position. The shut
off valve may have an aperture extending therethrough. In the
closed position, the aperture is in fluid communication between
converging outlet and the diverging inlet. When the shut off valve
is in the open position, the aspirator has high mass flow
performance to operate devices such as brakes. When the shut off
valve is in the closed position, flow through the aspirator is
reduced, but not entirely shut off. Accordingly, the shut off valve
can be opened to evacuate a brake booster quickly, and closed to
reduce an amount of leakage through the system. However, the
aperture allows enough leakage to work the brakes if the shut off
valve fails and does not open.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0007] FIG. 1 illustrates a front view of prior art check valve
aspirator.
[0008] FIG. 2 illustrates a cross-sectional view of a prior art
check valve aspirator.
[0009] FIG. 3 illustrates a top view of a prior art check valve
aspirator.
[0010] FIG. 4 illustrates a cross-sectional view of an aspirator
formed in accordance with an embodiment and having a shut off valve
in a closed position.
[0011] FIG. 5 illustrates a cross-sectional view of the aspirator
shown in FIG. 3 and having the shut off valve in the open
position.
[0012] FIG. 6 illustrates a cross-sectional view of the shut off
valve shown in FIG. 3 in the closed position.
[0013] FIG. 7 illustrates a cross-sectional view of the shut off
valve shown in FIG. 3 in the open position.
[0014] FIG. 8 illustrates a cross-sectional view of an aspirator
formed in accordance with an embodiment and having a shut off valve
in a closed position.
[0015] FIG. 9 illustrates a cross-sectional view of the aspirator
shown in FIG. 7 and having the shut off valve in the open
position.
[0016] FIG. 10 illustrates a cross-sectional view of the shut off
valve shown in FIG. 7 in the closed position.
[0017] FIG. 11 illustrates a cross-sectional view of the shut off
valve shown in FIG. 7 in the open position.
DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS
[0018] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiment illustrated in the drawings, and specific language will
be used to describe that embodiment. It will nevertheless be
understood that no limitation of the scope of the invention is
intended. Alterations and modifications in the illustrated device,
and further applications of the principles of the invention as
illustrated therein, as would normally occur to one skilled in the
art to which the invention relates are contemplated and desired to
be protected. Such alternative embodiments require certain
adaptations to the embodiments discussed herein that would be
obvious to those skilled in the art.
[0019] A prior art check valve aspirator is illustrated in FIG. 1.
The internal configuration and operation of the prior art aspirator
is shown and described in U.S. Pat. No. 5,291,916. FIGS. 1-3 are
reproductions of the figures from U.S. Pat. No. 5,291,916. The
prior art check valve aspirator is commercially available from
Nyloncraft Incorporated (616 W. McKinley Ave, Mishawaka, Ind.
46545).
[0020] Referring to FIGS. 1-3, check. valve 10 is normally employed
in an internal combustion engine in the air flow line between the
engine block and the air intake port at the full mixing port,
normally a carburetor or fuel injection port. For clarity, the
engine, carburetor, hose connections, and subsystems are not shown,
and it is understood that these ports are common to the internal
combustion engines found in almost all vehicles.
[0021] The air flow system in the typical internal combustion
engine operates on the principle that as the engine operates, a
partial vacuum is created which pulls air through the air intake
port of the carburetor of fuel injector to aid in proper fuel
combustion. This vacuum has been found to be useful in
supplementing vacuum assist subsystems in the vehicle, particularly
brakes, automatic transmissions and most recently, air
conditioners. Check valve 10 provides the connection between the
main airway and the subsystem and serves to inhibit back pressure
from the subsystem from disturbing airflow through the main
airway.
[0022] Check valve 10 shown in the drawings include a substantially
one piece valve body 12 which is preferably formed of a top valve
half 14 and a bottom valve half 16. The designations of top and
bottom halves are for descriptive purposes only and are not
limitative of the orientation of valve 10 in the engine
compartment. Preferably, top valve half 14 is joined to bottom
valve half 16 by sonic welding, heating or other conventional
method prior to its use.
[0023] Bottom valve half 16 includes an air inlet 18 and an air
outlet 20 which are in direct air flow communication via air
passageway 22. In typical use in an internal combustion engine, air
inlet 18 will be connected via a conduit (not shown) to the air
intake port in the engine carburetor or other function member (not
shown). Air outlet 20 is preferably connected via a conduit (not
shown) to the vacuum port of the engine block (not shown).
[0024] As shown, bottom valve half 16 also includes lower valve
seats 24, 26. Each lower valve seat 24, 26 is defined by a
continuous outer wall 28, 29, and a bottom wall 30, 31. A bore 32,
33 is defined in each lower valve seat 24, 26 to allow for air flow
communication with air passageway 22. Each outer wall 28, 29 may
include stepped portion 58, 59 as shown to provide for ease in
mating with upper valve seats 25, 27, as described later in this
specification. A plurality of radially spaced fingers 34, 35 extend
integrally upwardly from each bottom wall 30, 31 and serve to
support a flexible seal member 36, 37. Air passageway 22 has an
opening 38 which allows for air communication between the
passageway and valve seat 24.
[0025] As shown in FIG. 2, air passageway 22 is defined by a
tapering outer passage 40 which narrows from inlet port 18 up to
the opening 38, and a widening passage 42 from opening 38 to the
intersection of passageway 22 and valve seat 26. This configuration
of passageway 22 is commonly known as a venturi conduit, whose
functions are well known to those skilled in the art.
[0026] Upper valve half 14 is adopted to mate with lower valve half
14 to form check valve 10. Upper valve half 14 as shown includes
inlet 44 and inlet 46 which may be connected in air flow
communication by air passageway 48. In a typical connection to an
internal combustion engine, inlet 44 will be connected via an air
hose (not shown) to a brake system (not shown) and inlet 46 will be
either capped or connected to another subsystem of a vehicle, such
as the air conditioner compressor (not shown).
[0027] As shown, upper valve half 14 includes valve seats 25, 27.
Each upper valve seat 25, 27 is defined by continuous outer wall
50, 51 and bottom wall 52, 53. A bore 54, 55 is defined in each
upper valve seat 25, 27 to allow for air communication with air
passageway 48 and inlets 44, 46. Bottom walls 52, 53 are preferably
of a smooth concave configuration as shown with bores 54, 55 of a
slightly lesser diameter than that of seals 36, 37. Each outer wall
50, 51 preferably has a circumferential groove 56, 57 substantially
complemental to the stepped portion 58, 59 of the lower valve seats
24, 26.
[0028] Check valve 10 is assembled by aligning valve seats 24, 26
with valve seats 25, 27 such that stepped portions 58, 59 are
aligned with grooves 56, 57. Seals 36, 37 are placed on fingers 34,
35, and the valve parts 14, 16 are then pressed together and joined
as by sonic welding or other common method. The preferred method of
joining valve parts 14, 16 will generally depend on the material
used to form the valve parts, in this embodiment an injection
molded heat resistant, rigid plastic. It is understood that an
suitable plastic or metal or other compound may be used in forming
check valve 10, which is now ready for implementation in the
internal combustion engine as follows.
[0029] With the above hose hook-ups mentioned above, check valve 10
functions as follows. As the engine (not shown) operates, it draws
air through inlet 18, passageway 22 and outlet 20. This creates a
partial vacuum valve seats 24-27 and passageway 48 to draw seals
36, 37 downward against fingers 34, 35. Due to the spacing of
fingers 34, 35 (FIG. 3) free air flow from passageway 48 to
passageway 22 is allowed. The partial vacuum created by the
operation of the engine serves in the vacuum assistance of the
operation of the brake, and, if desired, air conditioning
subsystems (not shown) in a common manner.
[0030] If for any reason, back pressure in one of the subsystems is
generated to create a positive air flow through passageway 48 to
inlets 44, 46 a reverse flow vacuum is generated to draw seals 36,
37 tight against valve seat bottom walls 52, 53 to prevent the
vacuum from interfering with the above described air flow through
passageway 22. The functioning of check valve 10 as thus far
described is well-known to those skilled in the art.
[0031] As shown in FIG. 2, the tapering and widening passageways
40, 42 create the novel venturi effect on the partial vacuum
generated during the operation of the engine (not shown). By their
configurations, passageways 40, 42 allow for a marked increase in
the velocity with reduced pressure of the air passing through
passageway 42. Due to the connection of passageway 22 and valve
seats 24, 25, a marked increase in the amount of air drawn through
passageway 48 and valve seats 25, 24 provides a significant boost
in the vacuum assist for the subsystems (not shown) As an example,
check valve 10 was tested in a conventional internal combustion
engine which normally pulls a vacuum of about seven inches of
mercury (7'' Hg). The observed vacuum at outlet 44 with valve 10 in
place was eighteen inches of mercury (18'' Hg) which amounts to a
157% increase generated due to the use of valve 10 with its venturi
effect passageways 40, 42.
[0032] As illustrated in FIGS. 4-7, an aspirator 210 is provided
that may be electronically operated based on signals received from
sensors within the engine. The aspirator 210 includes a vacuum
channel 216 and an outside air channel 218. The vacuum channel 216
extends between an inlet 212 and a bypass channel 213, and the
outside air channel 218 extends between an inlet port 215 and an
outlet port 236. The bypass channel 213 fluidly couples the vacuum
channel 216 and the outlet port 236. The vacuum channel 216 and the
outside air channel 218 are further fluidly coupled by a venturi
channel 240. A venturi pipe 220 is located in the outside air
channel 218. The venturi pipe 220 includes converging section 222
and a diverging section 224. A throat 226 connects the converging
section 222 and the diverging section 224. The converging section
222 extends between a converging inlet 228 and a converging outlet
230. The converging section 222 narrows from the converging inlet
228 to the converging outlet 230. In particular, the converging
inlet 228 has a diameter D.sub.1 that is greater than a diameter
D.sub.2 of the converging outlet 230. The diverging section 224
includes and diverging inlet 232 and a diverging outlet 234. The
diverging section 224 widens from the diverging inlet 232 to the
diverging outlet 234. In particular, the diverging inlet 232 has a
diameter D.sub.3 that is less than a diameter D.sub.4 of the
diverging outlet 234. The throat 226 extends between the converging
outlet 230 and the diverging inlet 232.
[0033] A shut off valve 250 (illustrated in detail in FIGS. 6 and
7) is positioned between the converging outlet 230 and the
diverging inlet 232. The shut off valve 250 is in fluid
communication with the converging outlet 230 and the diverging
inlet 232. In particular, the shut off valve 250 is positioned to
close the throat 226 of the venturi pipe 220. The shut off valve
250 is movable between an open position 221 (shown in FIGS. 5 and
7) and a closed position 223 (shown in FIGS. 4 and 6), wherein in
the open position 221, the throat 226 is open, and in the closed
position 223, the shut off valve 250 is positioned in the throat
226. The shut off valve 250 is moved between the open position 221
and the closed position 223 by a solenoid 252 positioned adjacent
to and coupled to the aspirator 210. The solenoid includes upper
bumpers 270 and lower bumpers 272 that the shut off valve 250
contacts when moving between the open position 221 and the closed
position 223. In particular, in the open position 221, the shut off
valve 250 contacts the upper bumpers 270, and in the closed
position 223, the shut off valve 250 contacts the lower bumpers
272. The bumpers 270 and 272 reduce noise when the shut off valve
250 moves between the open position 221 and the closed position
223. In one embodiment, the bumpers 270 and 272 are formed from
fluorosilicone rubber.
[0034] The shut off valve 250 may be electronically operated based
upon signals received from sensors within the engine 80, shown in
FIG. 14. When the brake booster vacuum 84, shown in FIG. 14, is
equalized with the engine vacuum, the shut off valve closes to
prevent air flow through the venturi throat 226 but to allow air
flow through the bypass valve 213. In one embodiment, the shut off
valve 250 remains open during an ignition cold start to allow the
engine intake manifold 80 to draw air from an air intake 82, shown
in FIG. 14, through the venturi pipe 220 to create a vacuum within
the brake booster 84. In one embodiment, when the engine throttle
valve is open, the shut off valve 250 will open if the brake
booster vacuum is less than 35 kPa, and the shut off valve 250 will
close if the brake booster pressure is greater than 35 kPa,
regardless of the intake manifold pressure. In one embodiment, when
the engine throttle valve is closed and the engine intake manifold
pressure is less than 50 kPa, the shut off valve 250 will open if
the brake booster pressure is less than 35 kPa, and the shut off
valve 250 will close if the brake booster pressure is greater than
35 kPa. In one embodiment, when the engine throttle valve is closed
and the engine intake manifold pressure is greater than 50 kPa, the
shut off valve 250 will close regardless of the brake booster
pressure. It should be noted that the examples given herein are
exemplary only, and the pressures described may vary based on
application and engine type.
[0035] The solenoid 252 requires a low force to move the shut off
valve 250 between the open position 221 and the closed position
223. Because of the low force required, the solenoid is capable of
being sized relatively small when compared to other shut off
valves. In one embodiment, the shut off valve 250 will not open
during a reverse flow event, such as may be created by a
turbocharger or a backfire.
[0036] When airflow through the venturi is completely shut off,
automobile subsystems, such as brakes, may have limited
functionality. Accordingly, if the sliding valve becomes stuck or
the actuator of the valve malfunctions, the vehicle is with limited
control of the automobile subsystems, which can be dangerous and
costly. As illustrated in FIGS. 8-11, an aspirator 110 includes a
vacuum channel 116 and an outside air channel 118. The vacuum
channel 116 extends between an inlet 112 and a bypass channel 113,
and the outside air channel 118 extends between an inlet port 115
and an outlet port 136. The bypass channel 113 fluidly couples the
vacuum channel 116 and the outlet port 136. The vacuum channel 116
and the outside air channel 118 are further fluidly coupled by a
venturi channel 140. A venturi pipe 120 is located in the outside
air channel 118. The venturi pipe 120 includes converging section
122 and a diverging section 124. A throat 126 connects the
converging section 122 and the diverging section 124. The
converging section 122 extends between a converging inlet 128 and a
converging outlet 130. The converging section 122 narrows from the
converging inlet 128 to the converging outlet 130. In particular,
the converging inlet 128 has a diameter D.sub.11 that is greater
than a diameter D.sub.12 of the converging outlet 130. The
diverging section 124 includes a diverging inlet 132 and a
diverging outlet 134. The diverging section 124 widens from the
diverging inlet 132 to the diverging outlet 134. In particular, the
diverging inlet 132 has a diameter D.sub.13 that is less than a
diameter D.sub.14 of the diverging outlet 134. The throat 126
extends between the converging outlet 130 and the diverging inlet
132.
[0037] A shut off valve 150 (illustrated in detail in FIGS. 10 and
11) is positioned between the converging outlet 130 and the
diverging inlet 132. The shut off valve 150 is in fluid
communication with the converging outlet 130 and the diverging
inlet 132. In particular, the shut off valve 150 is positioned to
close the throat 126 of the venturi pipe 120. The shut off valve
150 is movable between an open position 121 (shown in FIGS. 9 and
11) and a closed position 123 (shown in FIGS. 8 and 10), wherein in
the open position 121, the throat 126 is open, and in the closed
position 123, the shut off valve 150 is positioned in the throat
126. The shut off valve 150 is moved between the open position 121
and the closed position 123 by a solenoid 152 positioned adjacent
to and coupled to the aspirator 110. The solenoid includes upper
bumpers 170 and lower bumpers 172 that the shut off valve 150
contacts when moving between the open position 121 and the closed
position 123. In particular, in the open position 121, the shut off
valve 150 contacts the upper bumpers 170, and in the closed
position 123, the shut off valve 150 contacts the lower bumpers
172. The bumpers 170 and 172 reduce noise when the shut off valve
150 moves between the open position 121 and the closed position
123. In one embodiment, the bumpers 170 and 172 are formed from
fluorosilicone rubber.
[0038] The shut off valve 150 includes an aperture 154 extending
therethrough. In the open position 121, as illustrated in FIG. 12,
the shut off valve 150 does not block any of the venturi pipe 120.
The aperture 154 size is determined by tolerable flow rate for the
engine. In the closed position 123, as illustrated in FIG. 13, the
aperture 154 allows fluid communication between converging outlet
130 and the diverging inlet 132. The aperture 154 has an upstream
end 156 position adjacent the converging outlet 130 in the closed
position 123. The upstream end 156 has a diameter D.sub.15 that is
approximately the same as a diameter D.sub.12 of the converging
outlet 130. The aperture 154 also includes a downstream end 158
positioned adjacent the diverging inlet 132 in the closed position
123. In one embodiment, the downstream end 158 has a diameter
D.sub.16 that may be less than a diameter D.sub.13 of the diverging
inlet 132. The aperture 154 converges from the converging outlet
130 to the diverging inlet 132 in the closed position 123. In the
closed position 123 an opening 180 in the shut off valve 150 also
allows air to leak between the converging section 122 and the
vacuum channel 116 through the valve 140.
[0039] When the shut off valve 150 is in the open position 121, a
first volume of air flows from the converging outlet 130 to the
diverging inlet 132. When the shut off valve 150 is in the closed
position 123, a second volume of air flows from the converging
outlet 130 to the diverging inlet 132. The first volume of air is
greater than the second volume of air. When the shut off valve 150
is in the open position 121, air flows from the converging outlet
130 to the diverging inlet 132 at a first flow. When the shut off
valve 150 is in the closed position 123, air flows from the
converging outlet 130 to the diverging inlet 132 at a second flow
rate. The second flow rate is less than the first flow rate. Air
leaks through the aperture 154 when the shut off valve 150 is in
the closed position 123.
[0040] When the shut off valve 150 is in the open position 121, the
aspirator 110 has high mass flow performance to operate devices
such as brakes. When the shut off valve 150 is in the closed
position 123, flow through the aspirator 110 is reduced, but not
entirely shut off. Accordingly, the shut off valve 150 can be
opened to evacuate a brake booster quickly, and closed to reduce an
amount of leakage through the system. However, the aperture 154
allows enough leakage to work the brakes or other subsystems if the
shut off valve 150 fails and does not open.
[0041] The shut off valve 150 may be electronically operated based
upon signals received from sensors within the engine. When the
brake booster vacuum is equalized with the engine vacuum, the shut
off valve closes to prevent air flow through the venturi throat 126
but to allow air flow through the bypass valve 140. In one
embodiment, the shut off valve 150 remains open during an ignition
cold start to allow the engine intake manifold to draw air through
the venturi pipe 120 to create a vacuum within the brake booster.
In one embodiment, when the engine throttle valve is open, the shut
off valve 150 will open if the brake booster vacuum is less than 35
kPa, and the shut off valve 150 will close if the brake booster
pressure is greater than 35 kPa, regardless of the intake manifold
pressure. In one embodiment, when the engine throttle valve is
closed and the engine intake manifold pressure is less than 50 kPa,
the shut off valve 150 will open if the brake booster pressure is
less than 35 kPa, and the shut off valve 150 will close if the
brake booster pressure is greater than 35 kPa. In one embodiment,
when the engine throttle valve is closed and the engine intake
manifold pressure is greater than 50 kPa, the shut off valve 150
will close regardless of the brake booster pressure. It should be
noted that the examples given herein are exemplary only, and the
pressures described may vary based on application and engine
type.
[0042] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiment has been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
* * * * *