Patent Application
20060016477
The present invention relates, generally, to the fields of check valves and vehicle braking systems and, more specifically, to aspirating check valves for use with vehicle braking system boosters.
Most of today's vehicle power braking systems utilize vacuum developed at the intake manifold of a vehicle's internal combustion engine to assist in their operation. Such vehicle power braking systems, generally, include a brake booster having a housing that encloses a front chamber and a rear chamber which is separated from the front chamber by a moveable wall. The vacuum developed at the intake manifold is communicated to the front chamber by a conduit to create a partial vacuum in the front and rear chambers which suspends the moveable wall. Thereafter, when a driver of the vehicle presses on the vehicle's brake pedal to apply braking, the vacuum provided to the rear chamber is interrupted and the rear chamber is opened to atmospheric pressure, thereby creating a pressure differential across the moveable wall. The pressure differential causes the moveable wall to translate toward the front chamber which, in turn, causes a force to be transmitted by a push rod to a master brake cylinder connected to the brake booster. The force causes the brake fluid to become pressurized and to then be supplied through a conduit to the brake actuators located at the vehicle's front and rear wheels, thus causing braking of the vehicle.
As the vehicle's driver withdraws pressure from the vehicle's brake pedal, air at atmospheric pressure is allowed to flow from the rear chamber toward the front chamber. The air is evacuated from the front chamber by the vacuum developed at the intake manifold, thereby creating a partial vacuum once again in the front chamber and causing the moveable wall to be returned toward its suspended location. A check valve, which may be fixed to the outside of the brake booster housing or located within the brake booster housing, permits the flow of air from the front chamber.
According to certain safety standards established by the U.S. Department of Transportation, the pressure differential across the moveable wall of the brake booster cannot be less than a value specified for a vehicle. Unfortunately, the partial vacuum developed at the intake manifold may be lower under certain conditions and, hence, the pressure differential may not be sufficient at all times during operation of a vehicle for the vehicle to meet such standards. For example, during cold start conditions or when a vehicle's transmission, power steering, or climate control compressor is engaged, a loss of vacuum at the brake booster may occur. Further, a vehicle may use vacuum assist for many other purposes or systems such as climate control blend doors, parking brake release actuation, engine mount modulation, and fuel purge. As a consequence, less vacuum may be available for the vehicle's brake booster.
Therefore, there exists in the industry, a need for a check valve fixable to a brake booster which is operable to aspirate air from the brake booster and to enhance, or increase, the vacuum available to the brake booster, and that addresses these and other problems or difficulties which exist now or in the future.
Broadly described, the present invention comprises a vacuum enhancing check valve for direct connection to a vehicle brake booster which increases the partial vacuum provided to the brake booster and restricts the possible back flow of air into the brake booster. The vacuum enhancing check valve, in accordance with an exemplary embodiment thereof, comprises a valve body having a first air inlet port for connection through a conduit to an air intake of a vehicle internal combustion engine, a second air inlet port adapted for direct connection to a brake booster of a vehicle braking system, and an air outlet port adapted for connection through a conduit to an intake manifold of the vehicle internal combustion engine. The valve body defines a venturi therein which allows air to flow between the first air inlet port and the air outlet port in response to the partial vacuum present at the intake manifold and which reduces the pressure of the flowing air to a minimum at a throat portion of the venturi such that the air pressure at the throat portion is lower than the air pressure at the intake manifold. Thus, the partial vacuum present at the intake manifold is enhanced by the venturi to produce a greater partial vacuum at the throat portion of the venturi. By virtue of the throat portion of the venturi being in air communication with the second air inlet port, the air pressure at the second air inlet port tends toward the partial vacuum present at the throat portion, thereby providing a greater partial vacuum to a vehicle brake booster than would, otherwise, be available from the intake manifold.
The valve body, according to the exemplary embodiment, further defines a valve seat therein interposed between the venturi and the second air inlet port. A seal member located within the valve seat is adapted for movement between a first position in which air is induced to flow from the second air inlet port toward the venturi by the reduced air pressure at the throat portion of the venturi and a second position in which air is restricted from flowing from the venturi toward the second air inlet port.
Advantageously, the vacuum enhancing check valve of the present invention attaches directly to the brake booster of a vehicle braking system and enables the flow of air from the front chamber of the brake booster, but not into the front chamber. Thus, the vacuum enhancing check valve eliminates the need for a check valve located within the brake booster to perform the same function. The vacuum enhancing check valve of the present invention also operates as an aspirator to increase the partial vacuum produced by the intake manifold of a vehicle's internal combustion engine for use by the vehicle's braking system and, potentially, by other vehicle devices or systems which require a vacuum assist. Formerly, such vacuum enhancement was performed by an aspirator positioned within a conduit between the intake manifold and braking system of a vehicle. Therefore, the vacuum enhancing check valve also eliminates the need for an aspirator located within a conduit and the need for a conduit extending between the aspirator and brake booster. Hence, the vacuum enhancing check valve replaces at least three or more components within a vehicle, thereby reducing the vehicle's cost and complexity and improving the vehicle's reliability. Further, the relative orientation of the air inlet ports and air outlet port of the vacuum enhancing check valve enables easy insertion of the second air inlet port directly into a brake booster absent interference with a conduit(s) attached before or after such insertion.
Other objects, features, and advantages of the present invention will become apparent upon reading and understanding the present specification when taken in conjunction with the appended drawings.
Referring now to the drawings in which like numerals represent like elements throughout the several views,
The first valve portion 14 has an air inlet port 18 and an opposed air outlet port 20 which are collinearly disposed along a longitudinal axis 22 extending therebetween as seen in
The wall 24 also defines, as illustrated in the sectional view of
The first valve portion 14 further comprises first portion valve seats 42, 44 which, respectively, include first and second bores 46, 48 defined by wall 24. The first and second bores 46, 48, generally, have circular cross-sections. Wall 24 further defines a channel 50 extending between the first bore 46 and the throat portion 40 of passageway 34 to enable the passage of air between first bore 46 and passageway 34 (and, hence, between first portion valve seat 42 and passageway 34). Second bore 48 is in direct air communication with passageway 34. Wall 24 also has tongues 52, 54 which improve and enable mating of first portion valve seats 42, 44 with second portion valve seats 74, 76 (described below) during joining of the first and second valve portions 14, 16 together. Wall 24 additionally, as viewed best in the bottom plan view of
The second valve portion 16 is adapted to mate with the first valve portion 14 during the manufacture of the vacuum enhancing check valve 10. The second valve portion 16, as displayed in
The second valve portion 16 comprises a wall 66 which defines an opening 68 therein at air inlet port 62. The openings 68 has a, generally, circular cross-section. The wall 66 has a brake booster interface 70 at air inlet port 62 for improving the retention and securing of air inlet port 62 within an opening 104 and grommet 108 of the housing 100 of a vehicle brake booster 96, as described below, when the vacuum enhancing check valve 10 is in use. In the exemplary embodiment, the brake booster interface 70 comprises a plurality of barbs protruding at air inlet port 62 and extending around opening 68. The wall 66 also has a shoulder 72 which extends around the air inlet port 62 inboard of the brake booster interface 70. The shoulder 72 serves as a stop which limits travel of the air inlet port 62 into the opening 104 and grommet 108 of a housing 100 of a vehicle brake booster 96 during insertion of the air inlet port 62 therein.
As illustrated in
It should be noted that, in other exemplary embodiments of the present invention, wall 66 may define additional air inlet ports which are in air communication with chamber 82. The additional air inlet ports may be connected to other vehicle devices or systems which may require vacuum or vacuum-assist such as, for example and not limitation, a climate control compressor, climate control blend doors, transmission, cruise control system, parking brake release actuator, engine mount modulator, and fuel purge system.
The vacuum enhancing check valve 10 is assembled by aligning first portion valve seats 42, 44 and second portion valve seats 74, 76 such that the tongues 52, 54 of wall 24 are aligned with grooves 90, 92 of wall 66. Seal members 60, 61 are then positioned in contact with and resting on the protruding fingers 56, 58 of wall 24. The first and second valve portions 14, 16 are subsequently pressed together and joined by sonic welding, heating, or other appropriate method or technique. The particular method or technique used to join the first and second valve portions 14, 16 generally depends on the material from which they are formed.
The vacuum enhancing check valve 10 is, generally, for use in conjunction with a vehicle braking system 94 having a brake booster 96 and master cylinder 98 assembly adapted for use therewith as displayed in the top plan and left side, elevational views of
In use, the vacuum enhancing check valve 10 is secured directly to the housing 100 of a vehicle's brake booster 96, as illustrated in
During operation of the vehicle with the vacuum enhancing check valve 10 installed as described above, the vehicle's engine creates a partial vacuum at its intake manifold causing air to flow through the first and second conduits and, hence, through air inlet port 18 and air outlet port 20. As air is drawn through air inlet port 18 toward air outlet port 20, the air is accelerated as it passes through passageway 34 with its velocity being increased and pressure further reduced by the venturi of passageway 34. By virtue of the further reduction in the pressure of the air caused by the venturi, the partial vacuum created by the vehicle's engine is significantly enhanced by the vacuum enhancing check valve 10. The further reduction in pressure (i.e., the significant enhancing of the partial vacuum) within passageway 34 causes the seal members 60, 61 to be drawn against the protruding fingers 56, 58 extending within first and second bores 46, 48 of first portion valve seats 42, 44. With the seal members 60, 61 in such position, air is allowed to flow from chamber 82 to passageway 34 via the first and second portion valve seats 42, 44, 74, 76. As a consequence, air is also drawn into chamber 82 through air inlet port 62, thereby creating a partial vacuum within air inlet port 62 and providing a vacuum assist to the brake booster 96 (and, hence, to the vehicle's braking system).
Typically, a conventional vehicle internal combustion engine creates a partial vacuum of approximately seven inches of mercury (7″ Hg) at its intake manifold during operation. The vacuum enhancing check valve 10 of the present invention enhances this partial vacuum such that the partial vacuum at air inlet port 62 is approximately eighteen inches of mercury (18″ Hg). This enhancement constitutes a 157% increase in partial vacuum which is due, at least in part, to the venturi configuration of passageway 34.
If, for any reason, the direction of air flow is caused to be reversed in chamber 82 and air inlet port 62, seal members 60, 61 are drawn against the first and second concave portions 86, 88 of second portion valve seats 74, 76. Thus, the vacuum enhancing check valve 10 also operates as a check valve similar to those check valves employed within or attached to brake boosters of many vehicle braking systems.
Whereas the present invention has been described in detail above with respect to an exemplary embodiment thereof, it is understood that variations and modifications can be effected within the spirit and scope of the invention, as described herein before and as defined in the appended claims.
