Noise suppression system and method
A noise suppression assembly includes a first venturi configured to provide air to a combustion chamber and a second venturi configured to provide air to the combustion chamber. The noise suppression assembly also includes a valve subsystem configured to selectively limit air flow through at least one of the first venturi and the second venturi.
Internal combustion engines have traditionally utilized a throttle to regulate airflow to the combustion chamber of a cylinder. Improvements in electronic engine control have enabled the intake and exhaust valves of the cylinder to control airflow, thereby eliminating the need for a traditional throttle. Such engines are commonly referred to as electronic valve actuated engines and/or throttleless engines. Throttleless engines can demonstrate improved performance, fuel economy, transient response, combustion stability, and emissions when compared to conventionally throttled engines.
However, the inventors herein have recognized a potential disadvantage of throttleless engines. Specifically, induction noise can be significantly greater when a throttle is not present. This is particularly true at low engine speeds, where traditional throttled designs have had a substantially closed throttle plate that reflects induction noise. Throttleless engines have a substantially unobstructed passage to the combustion chamber, which can significantly increase induction noise. Furthermore, the actuation of the electronic valves themselves may increase induction noise, thereby exacerbating induction noise issues.
SUMMARY OF THE INVENTIONA system and method for controlling induction noise are provided. In some embodiments, the system includes a noise suppression assembly including a first venturi configured to provide air to a combustion chamber and a second venturi configured to provide air to the combustion chamber. The noise suppression assembly also includes a valve subsystem configured to selectively limit air flow through at least one of the first venturi and the second venturi. In this manner, air flow can be controlled to satisfy the air requirements of an engine and simultaneously limit induction noise. During operation under low air requirements (such as low engine speed or low engine torque), one or more venturi may be at least partially blocked, thereby suppressing induction noise that could otherwise escape through the venturi.
In some embodiments, a noise suppression assembly may include one relatively large venturi and one relatively small venturi. During high engine air requirement operation, both venturis may supply air to the engine. During low engine air requirement operation, the large venturi can be closed, thereby suppressing induction noise that could otherwise escape through the large venturi.
BRIEF DESCRIPTION OF THE FIGURES
Combustion chamber 14 is an area where chemical energy stored in fuel can be converted to mechanical energy. For example, an electronic engine controller 30 can be configured to control operation of intake valve 20, exhaust valve 22, fuel injector 24, and/or spark plug 26 to facilitate internal combustion within combustion chamber 14. In other words, intake valve 20 and exhaust valve 22 may cooperate with fuel injector 24 to create a desired air-to-fuel ratio in the combustion chamber. The controller receives various inputs from sensors, such as a measure of exhaust air-fuel ratio from sensor 110 (which can be a UEGO sensor or a HEGO sensor, for example), a measure of engine speed from speed sensor 112; a measure of airflow from mass air flow sensor 114, a measure of manifold pressure from pressure sensor 116, and various others not shown here, such as a measure of pedal position from a foot pedal position sensor, a measure of engine temperature from a coolant temperature sensor, a measure of airflow temperature from an air temperature sensor, and a measure of exhaust temperature from an exhaust temperature sensor. Further, these parameters can be estimated in controller 30 using estimation models and/or other techniques.
Spark plug 26 can be used to ignite the air and fuel mixture, thereby facilitating a controlled explosion that transfers chemical energy stored in the fuel into mechanical energy in the form of piston 18 recoiling from the explosion. Linear energy of piston 18 can be converted to rotational energy at a crankshaft 32, and such rotational energy can be utilized to drive one or more wheels of a vehicle.
As shown in
Conventionally throttled engines utilize a throttle to regulate airflow through the intake manifold to the combustion chamber. In such engines, a partially closed throttle reflects most of the acoustic energy back to the engine while allowing adequate airflow to the cylinders. Without the throttle, there is virtually no resistance to the escape of acoustic energy. Therefore, throttleless engines can have substantially higher induction noise levels than conventionally throttled engines, especially when the engine is operated at low speeds.
The inventors herein have developed a system for decreasing induction noise, which, for example, can be used in throttleless engines. As schematically shown in
It should be understood that venturi 60 is provided as a nonlimiting example, and other venturi configurations are within the scope of this disclosure. For example, upstream portion 70 may be shortened and/or downstream portion 74 may be lengthened so that the downstream portion forms a greater percentage of the venturi. Conversely, downstream portion 74 may be shortened and/or upstream portion 70 may be lengthened so that the downstream portion forms a greater percentage of the venturi. In some embodiments, upstream portion 70 may effectively be reduced to a rim along the mouth of the venturi, and the throat portion of the venturi may be located substantially at the opening of the venturi.
As illustrated in
Venturi 62 can be configured with the same general characteristics as venturi 60, namely a relatively narrow throat portion between relatively wider upstream and downstream portions. The reduction ratio of venturi 62 can be the same as the reduction ratio of venturi 60, or venturi 60 and venturi 62 can be configured with different reduction ratios. Furthermore, venturi 60 and venturi 62 can be similarly sized, or venturi 60 and venturi 62 can be differently sized, as is shown in
An engine can operate throughout a plurality of engine operating conditions, characterized by engine speed (RPM), load, torque, etc. Increasing demands on an engine generally correspond to increased air requirements. As is schematically shown in
An air requirement operation state may be determined by engine RPMs, load, torque, oxygen levels, and/or other parameters corresponding to the amount of air that can be utilized for internal combustion. For example, an air requirement operation state can correspond to the revolutions per minute of the engine and can be monitored by electronic engine controller 30. As a nonlimiting example, the electronic engine controller can be configured to treat anything less than 1500 RPMs as low engine air requirement operation, and anything equal to, or greater than, 1500 RPMs as high engine air requirement operation. Alternatively, the air requirement can be determined by measuring airflow through the engine, such as via mass air flow sensor 114 and/or manifold pressure sensor 116.
As shown in
The pressure drop in the throat portion of a venturi, such as venturi 60 and/or venturi 62, can be used as an introduction location for stored evaporative emissions. A conventional throttleless engine may have essentially atmospheric pressure in the intake manifold, thereby hindering flow between a canister and the manifold because no pressure drop is present. However, a venturi can be used as a vacuum source to drive flow from the canister to the intake manifold. Further, unlike conventional engines, as engine speed and load increase, the pressure drop in the venturi increases. This allows purge flow throughout the operating region of the engine. The venturi can also be used to provide a vacuum source for brake boost and/or exhaust gas recirculation.
Noise suppression has been tested using differently sized venturis. In particular, three venturis were designed such that the effective open area at the throat was 50%, 25%, and 15% of the original area at the mouth of the upstream portion of the venturi. Each of these cases represents a closed valve situation corresponding to low engine air requirement operation. Engine speeds of 650 rpm, 2500 rpm, and 5500 rpm were used as test cases.
One method for controlling throttleless engine noise is now described. The method includes first placing a first venturi intermediate a combustion chamber and an air supply, wherein the first venturi includes a first throat portion having a smaller cross-sectional area than adjacent upstream and downstream portions of the first venturi. As described above with reference to
Referring now to
When the answer to step 1512 is Yes, the routine continues to step 1514 where a desired gate valve position is determined based on the determined operating conditions. For example, the valve can be simply set to a fully closed/open position, or to an intermediate position in some examples during selected conditions. Then, in step 1516, the routine adjusts the commanded signal sent to the valve to place it in the desired position.
In this way, improved noise suppression can be obtained.
Referring now to
Further, since the venturi can reduce the engine vibration and acoustic noise, it may also be able to reduce engine pulsations that can corrupt a mass air flow sensor measurement. As such, placing a mass air flow sensor (such as sensor 114) near a throat of one or both of the venturi may provide beneficial measurement of flow due to reduce engine pressure pulsations. However, robustness and durability of the sensor typically require clean air, and so the mass airflow sensor needs to be placed after some air filtering media. Thus, if used in the venturi, some air filtering could be added upstream of the venturi.
Although described above in the context of a four stroke internal combustion gas engine, it should be understood that it is within the scope of the present disclosure to utilize a plural venturi system to decrease perceived noise in virtually any application in which controllable air supply is desired. While the present disclosure has been provided with reference to the foregoing operational principles and embodiments, it will be apparent to those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope defined in the appended claims. For example, an the above features can be used with throttled engines having an electronically controlled throttle, or mechanically actuated throttle, if desired. The present disclosure is intended to embrace all such alternatives, modifications and variances. Where the disclosure or claims recite “a,” “a first,” or “another” element, or the equivalent thereof, they should be interpreted to include one or more such elements, neither requiring nor excluding two or more such elements.
Claims
1. A noise suppression assembly, comprising:
- a first venturi configured to provide air to a combustion chamber;
- a second venturi configured to provide air to the combustion chamber; and
- a valve subsystem configured to selectively limit air flow through at least one of the first venturi and the second venturi.
2. The noise suppression assembly of claim 1, wherein the first venturi is sized for greater maximum throughput than the second venturi.
3. The noise suppression assembly of claim 2, wherein the valve subsystem includes a valve configured to selectively close the first venturi.
4. The noise suppression assembly of claim 1, wherein the valve subsystem is configured to close the first venturi during low engine air requirement operation.
5. The noise suppression assembly of claim 1, wherein the valve subsystem is configured to open the first venturi during high engine air requirement operation.
6. The noise suppression assembly of claim 1, wherein the first venturi is positioned in a parallel airflow configuration with the second venturi.
7. The noise suppression assembly of claim 1, further comprising an air box intermediate the combustion chamber and the first and second venturi.
8. The noise suppression assembly of claim 1, wherein the second venturi includes a mouth and a throat, and wherein a cross-sectional area of the throat is at most half a cross-sectional area of the mouth.
9. The noise suppression assembly of claim 1 further comprising a filter located upstream of said first venturi.
10. The noise suppression assembly of claim 9 wherein said filter is located upstream of said second venturi.
11. The noise suppression assembly of claim 1 further comprising a mass air flow sensor.
12. A noise suppression assembly, comprising:
- a first passage configured to be positioned intermediate a combustion chamber and an air supply, wherein the first passage includes a first upstream portion, a first downstream portion, and a first throat portion between the first upstream portion and the first downstream portion, wherein a cross-sectional area of the first throat portion is less than a cross-sectional area of the first upstream portion and less than a cross-sectional area of the first downstream portion;
- a second passage configured to be positioned intermediate the combustion chamber and the air supply in parallel with the first passage, wherein the second passage includes a second upstream portion, a second downstream portion, and a second throat portion between the second upstream portion and the second downstream portion, wherein a cross-sectional area of the second throat portion is less than a cross-sectional area of the second upstream portion and less than a cross-sectional area of the second downstream portion; and
- a valve configured to selectively restrict air flow from the air supply to the combustion chamber through the first passage.
13. The noise suppression assembly of claim 12, wherein the first throat portion has a greater cross-sectional area than the second throat portion.
14. The noise suppression assembly of claim 13, wherein a minimum cross-sectional area of the second throat portion is at most 50% a minimum cross-sectional area of the first throat portion.
15. The noise suppression assembly of claim 13, wherein a minimum cross-sectional area of the second throat portion is at most 25% a minimum cross-sectional area of the first throat portion.
16. The noise suppression assembly of claim 13, wherein a minimum cross-sectional area of the second throat portion is at most 15% a minimum cross-sectional area of the first throat portion.
17. The noise suppression assembly of claim 12, wherein the first passage has a greater maximum throughput than the second passage.
18. The noise suppression assembly of claim 17, wherein the valve is configured to block air flow through the first passage during low engine air requirement operation.
19. A method of controlling an engine, where the engine includes a first venturi intermediate a combustion chamber and an air supply, wherein the first venturi includes a first throat portion having a smaller cross-sectional area than adjacent upstream and downstream portions of the first venturi, and a second venturi intermediate the combustion chamber and the air supply in parallel with the first venturi, wherein the second venturi includes a second throat portion having a smaller cross-sectional area than adjacent upstream and downstream portions of the second venturi, the engine further including a valve coupled to at least one of the first and second venturi the method comprising:
- adjusting the valve to adjust an amount of flow through the valve as engine operating conditions vary.
20. The method of claim 19, wherein said adjusting selectively blocks air flow based on engine air requirements.
21. The method of claim 20 wherein said selective blocking includes blocking the first venturi during low engine air requirement operation.
22. The method of claim 19, wherein the first venturi has a greater maximum air throughput than the second venturi.
23. The method of claim 19, wherein a cross-sectional area of the first throat portion is less than a cross-sectional area of the second throat portion.
24. The method of claim 23, wherein said adjusting includes closing the first venturi during low engine air requirement operation.
Type: Application
Filed: Feb 12, 2004
Publication Date: Sep 1, 2005
Inventors: Lloyd Bozzi (Ypsilanti, MI), Sunny Khosla (Ann Arbor, MI)
Application Number: 10/778,530