Patent Application
20080144850
This invention relates generally to the control the noise generated by an automotive vehicle and, more particularly, to the reduction of noise in the passenger compartment of an automotive vehicle by controlling the transmission of the noise along the acoustic transfer path from the source of the noise to the receiver of the noise.
The operation of the powertrain in an automobile is one of the major contributors of noise received within the passenger compartment of the automobile. With new powertrain technology, such as electronic valve actuation and variable displacement engine, new methods are needed to control the interior noise. In order to improve customer perceived interior noise quality, passenger compartment active noise control has been a popular strategy for study. Such methods of noise control are discussed below relative to prior art documents. Generally, these methods are expensive and only control the receiving end of the problem such as the passenger driver's ear positions, which can affect the speech intelligence to the passenger. Other methods of controlling noise are directed to the source, such as an active control of the induction or exhaust systems, have been developed. However, active control capability is limited and is very complex and expensive. Therefore, active noise control systems have not proven to be popular even though the methodology and technical capability have existed for many years.
An example of active passenger cabin sound suppression technology can be found in U.S. Pat. No. 4,506,380 granted to Shinichi Matsui on Mar. 19, 1985, in which speakers disposed in the dash panel of the vehicle are individually energized to selectively control the resonance occurred with respect to engine vibration. Similarly, an active vibration/noise control system in taught in U.S. Pat. No. 5,386,372, issued on Jan. 31, 1995, to Toshiski Kobayashi, et al, wherein speakers are arranged in suitable locations in the dashboard of the passenger compartment to control the noise from the engine. Self-expanding engine mounts have actuators formed of piezo-electric elements or magnetostrictive elements to prevent the vibrations from being transmitted from the engine.
Passive sound-absorbing materials are utilized throughout an automotive vehicle to reduce noise transmission. An example is found in U.S. Pat. No. 7,017,250, issued to Girma Gebreselassie, et al, on Mar. 28, 2006, wherein a dash insulator system has a substrate made from foam that is used to absorb the sound directed to a dash insulator. In U.S. Pat. No. 4,574,915, granted to Heinemann Gahlaii, et al on Mar. 11, 1986, sound-insulating cladding, formed from viscoelastic foam material is secured on the face of the front bulkhead to provide a sound-insulated area. Sound absorbing materials are used in the dashboard area of the vehicle to provide a passive noise control system preventing the noise generated in the engine compartment from being transmitted to the passenger compartment, as is suggested in U.S. Pat. No. 5,094,318, granted to Takashi Maeda, et al on Mar. 10, 1992; in U.S. Pat. No. 5,554,831, granted to Hiroshi Matsukawa, et al on Sep. 10, 1996; in U.S. Pat. No. 5,817,408, granted to Motohiro Orimo, et al on Oct. 6, 1998; in U.S. Pat. No. 6,102,465, granted to Kouichi Nemoto on Aug. 15, 2000; and in U.S. Pat. No. 6,554,101 granted to Kyoichi Watanabe on Apr. 29, 2003.
An isolator system, comprised of cast foam, is affixed to horizontal and vertical portions of the vehicle dash panel to reduce the transmission of unwanted noise and vibration from the engine compartment is taught in U.S. Pat. No. 6,767,050 granted to Christian Junker on Jul. 27, 2004, and assigned to Ford Global Technologies, LLC, and in U.S. Pat. No. 7,070,848 granted to Michael Campbell on Jul. 4, 2006. An automotive dash insulator system, used to reduce noise transmission from the engine to the interior of the vehicle, is formed with a sound-absorbing layer comprised of a viscoelastic foam as depicted in U.S. patent application Publication No. 2005/0150720, of Jay Tudor, et al, published on Jul. 14, 2005.
A noise control system using a piezo-electric control scheme can be found in U.S. Pat. No. 6,589,643, granted on Jul. 8, 2003, to Jun Okada, et al, in which sound absorbing material, such as piezo-electric material, is used to insulate a dashboard in a vehicle to absorb and prevent the entry of low-frequency noise from the engine into the passenger compartment. In U.S. patent application Publication No. 2004/0130081 of David Hein, published on Jul. 8, 2004, a piezo-electric actuator and sensor assemblies are introduced between various structures contained within the instrument panel to minimize vibration within the instrument panel structure.
Adaptive filters have also been used to control noise generated from a noise source, such as the engine in an automobile, as taught in U.S. Pat. No. 5,131,047, issued to Hiroyuki Hashimoto, et al on Jul. 14, 1992, where a speaker is utilized to reproduce engine noise that cancels the generated engine noise. In U.S. Pat. No. 5,321,759, granted to Yi Yuan on Jun. 14, 1994, adaptive filters having transversal filters are utilized in an active noise control system to cancel engine generated vibrational noise. A directional microphone is integrated into the dashboard to achieve a directional effect for controlling automotive noise is taught in U.S. Pat. No. 6,305,732, granted on Oct. 23, 2001, to Hans-Wilheim Ruhl. In U.S. Pat. No. 6,324,294, issued on Nov. 27, 2001 to Henry Azima, et al, loud speaker panels are attached to or installed in the dashboard of an automobile. U.S. patent application Publication No. 2004/0240678 of Yoshio Nakamura, et al, published Dec. 2, 2004, discloses an active noise control system that uses a speaker to control problematic noise generated by the engine.
It would be desirable to provide a system for reducing engine noise that is directed to the transfer path, rather than the source or the receiver of the noise.
It is an object of this invention to overcome the aforementioned disadvantages of the known prior art by providing a noise control system that is directed to the transfer path of the noise transmission.
It is another object of this invention to provide an active control system for noise generated at the engine that is deployed within the dual bulkhead plenum of an automotive dashboard.
It is a feature of this invention that the dual bulkhead plenum in the vehicle dashboard is located along the transfer path along which engine noise is transmitted into the passenger compartment.
It is an advantage of this invention that utilization of sound control techniques within the dual bulkhead plenum is directed to the transmission of the noise, as opposed to being directed to the source or receiver of the noise.
It is another advantage of this invention that the active acoustic transfer function provides an efficient control of the noise transmitted to the cabin of the automotive vehicle through the dash panel.
It is another feature of this invention that the constrained volume of the dual bulkhead plenum helps to provide a more efficient noise control system.
It is still another advantage of this invention that the deployment of simple hardware or software systems can provide a low cost and high capability active noise control within the dual bulkhead plenum of the vehicle dashboard to affect noise within the passenger compartment.
It is still another object of this invention to reduce the transmission of engine noise into the passenger compartment of an automotive vehicle by interrupting the transfer path of the noise transmission.
It is still another feature of this invention to provide an active noise control within the dual bulkhead of an automotive dashboard.
It is yet another feature of this invention to utilize speakers within the dual bulkhead plenum to control engine noise being transmitted through the plenum.
It is yet another advantage of this invention that the plenum can be damped with sound absorbing acoustic materials attached to the surface of the sheet metal forming the bulkhead.
It is a further feature of this invention that the dual bulkhead plenum can be broken into chambers into which separate noise attenuation devices can be positioned.
It is another feature of this invention that the level of noise control can be varied from chamber to chamber.
It is a further advantage of this invention that the noise control system is placed in a less harsh environment than being utilized at the source of the noise.
It is still a further advantage of this invention that the noise control system can be adapted to any automotive vehicle utilizing a dual bulkhead instrument dash panel design.
It is yet another object of this invention to provide a noise control system directed to the transmission transfer path of the noise, which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use.
These and other objects, features and advantages are accomplished according to the instant invention by providing a noise control system directed to the path along which the noise is being transmitted from the source of the noise being generated to the receiver of the noise in the passenger compartment of an automotive vehicle. The noise control system is deployed in a box structure, such as the dual bulkhead of the dashboard of the vehicle, to provide a constrained volume within which engine noise can be controlled. The dual bulkhead plenum houses an active noise control apparatus, such as a speaker or a vibrating device, between the bulkheads to be operable with a control algorithm to generate sound that can control the noise or vibrations generated by the engine. The plenum can also be treated with passive noise control materials, such as viscoelastic damping materials, acoustical foam or heavy vinyl barrier and foam to block airborne sound and vibrations, in addition to the active noise control.
The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:
Referring to
To control acoustic transfer functions between the source, e.g. the engine 13, and the receiver, e.g. the passenger cabin 12 of the automobile 10, a box-like structure, which is defined with respect to the instant application as being a structure having a fixed volume, is placed along the transfer path between the generator and receiver. In some automotive vehicles 10, the instrument panel 15 is provided with a dual bulkhead plenum 20 located between the engine 13 and the passenger compartment 12. The dual bulkhead plenum 20 provides a suitable box-like structure for controlling the transfer of sound waves or vibrations along the transfer path through the instrument panel 15 in to the passenger compartment 12. Due to the lower level of sound or vibrational energy passing through the plenum 20 and the constrained volume of the plenum 20, very low cost, yet high capability, active noise control system can be utilized within the plenum 20 utilizing relatively simple hardware and software systems.
The noise control system 30 can include sensors 31 within the engine compartment to identify the frequency and amplitude of the sound energy being produced by the engine 13 for transfer to the passenger compartment 12 through the dual bulkhead plenum 20, and sensors 32 within the passenger compartment 12 to identify the frequency and amplitude of the sound energy being transmitted into the passenger compartment 12. These sensors can be utilized in an open loop control system with a control algorithm that can result in the production of a countering sound wave introduced by speakers 35 within the plenum 20.
Preferably, the control system is a closed loop system in which the sensors 31, 32 are used to detect operational parameters for the vehicle, such as speed of operation, ambient temperature, weather conditions, RPM level of the engine, etc. The controller 25 employs a mathematical model of the vehicle's acoustic response to these environmental conditions through a control algorithm and generates a countering sound wave in response to the predicted sound energy level.
Accordingly, speakers 35 are placed within the plenum 20 to introduce the countering sound energy to control the sound waves being transmitted along the transfer path through the plenum 20. Vibrational energy can also be countered by opposing counteractive vibrational energy, which can be induced into the plenum 20 by a vibrator 36, schematically depicted in
Alternatively, or as an optional addition to the speakers 35 and or vibrators 36, the plenum 20 can be lined with acoustic materials 27, 29, as are depicted in
It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.
For example, this noise control technology can be adapted and expanded for use in other vehicle structures, such as the wheel fender and trunk, wherever a fixed volume can be realized within the confines of the vehicle structure. Other applications of this noise control technology would include construction equipment, and other heavy equipment, the aerospace industry, and the heating, ventilation and air conditioning industry.
