Sound generator for mounting on a vehicle to manipulate vehicle noise

Abstract

A sound generator (100) mounts on a vehicle to manipulate vehicle noise originating from a vehicle operated by an internal combustion engine. The sound generator (100) includes a casing (110), a loudspeaker (120), and at least one pressure compensation valve (130). The loudspeaker (120) and the casing (110) together thereby enclose a volume (115). Further, the pressure compensation valve (130) couples the volume (115) enclosed by the loudspeaker (120) and the casing to an outside of the casing (110). The pressure compensation valve (130) thereby extends through a plane in which the loudspeaker (120) is located. A system (200) for manipulating sound waves propagating through exhaust systems of vehicles driven by an internal combustion engine uses the above sound generator (100).

Claims

1. A system for manipulating sound waves propagating through an exhaust system of a vehicle driven by an internal combustion engine, the system comprising: a controller connected to an engine controller of the vehicle by a control line or built-in into the engine controller of the vehicle; and at least one sound generator comprising: a casing; a loudspeaker, the loudspeaker and the casing together enclosing a volume and the loudspeaker extending along a loudspeaker plane; and at least one pressure compensation valve, the pressure compensation valve coupling the volume enclosed by the loudspeaker and the casing with an outside of the casing and the pressure compensation valve extending through the loudspeaker plane, the at least one pressure compensation valve comprising a valve body and a valve head, the valve body having a first end with a first opening formed therein that opens to the outside of the casing, and a second end with a second opening accommodating the valve head, the valve head being disposed inside the volume enclosed by the loudspeaker and the casing, the valve head including a through hole for air, the first opening of the valve body being located in the loudspeaker plane; a control line connecting the loudspeaker to the controller, wherein the controller is configured to generate a control signal based on signals received from the engine controller and to output the control signal to the loudspeaker via the control line, the control signal being adapted to cancel the sound waves propagating through the exhaust system of the vehicle to some extent or completely, when the control signal is used to operate the loudspeaker.

2. A system according to claim 1, wherein the valve head comprises a membrane in a valve head interior, the membrane being permeable to air and impermeable to water and closing the through hole.

3. A system according to claim 1, wherein the loudspeaker comprises: a loudspeaker basket; a membrane retained airtight by the loudspeaker basket; a permanent magnet retained by the loudspeaker basket; a voice coil retained by a voice coil carrier, the voice coil being located in a constant magnetic field generated by the permanent magnet and the voice coil being coupled to the membrane wherein: the loudspeaker basket is coupled airtight to the casing; and the valve body penetrates the loudspeaker basket or the valve body is coupled airtight to the loudspeaker basket with the first opening of the valve body being aligned with an opening formed in the loudspeaker basket.

4. A system according to claim 1, wherein the at least one pressure compensation valve is positioned in the casing and the valve body is dimensioned such that the valve head is disposed opposite the loudspeaker plane and is located at a maximum distance to the loudspeaker plane.

5. A system according to claim 1, wherein the valve body includes an increased diameter section between the first opening and the second opening and a diameter of the increased section of the valve body is increased with respect to a diameter of the first opening or the second opening or both the first opening and the second opening.

6. A system according to claim 5, wherein the increased diameter section is fully or in part located inside the casing.

7. A system according to claim 1, wherein a volume enclosed by the valve body between the first opening and the second opening amounts to between 1% and 20% of the volume enclosed by the loudspeaker and the casing.

8. A system according to claim 1, wherein a volume enclosed by the valve body between the first opening and the second opening amounts to between 4% and 15% of the volume enclosed by the loudspeaker and the casing.

9. A system according to claim 1, wherein the through hole of the valve head is a throttle enabling, at a constant pressure difference of 300 Pa and a passage of more than 2 liters of air per hour and less than 10 liters of air per hour.

10. A system according to claim 1, wherein the through hole of the valve head is a throttle enabling, at a constant pressure difference of 300 Pa and a passage of more than 3 liters of air per hour and less than 9.0 liters of air per hour.

11. A system according to claim 1, wherein the through hole of the valve head is a throttle enabling, at a constant pressure difference of 300 Pa and a passage of more than 4 liters of air per hour and less than 8 liters of air per hour.

12. A system according to claim 1, wherein the valve body is formed integrally with the casing.

13. A system according to claim 1, wherein the loudspeaker comprises: a loudspeaker basket; a membrane retained airtight by the loudspeaker basket; a permanent magnet retained by the loudspeaker basket; a voice coil retained by a voice coil carrier, the voice coil being located in a constant magnetic field generated by the permanent magnet and the voice coil being coupled to the membrane wherein: the loudspeaker basket is coupled airtight to the casing; and the valve body penetrates the loudspeaker basket or the valve body is coupled airtight to the loudspeaker basket with the first opening of the valve body being aligned with an opening formed in the loudspeaker basket.

14. A system according to claim 13, wherein the valve body is integrally formed with the loudspeaker basket.

15. A system according to claim 1, wherein the loudspeaker comprises: a loudspeaker basket; a membrane retained airtight by the loudspeaker basket; a permanent magnet retained by the loudspeaker basket; and a voice coil retained by a voice coil carrier, the voice coil being located in a constant magnetic field generated by the permanent magnet and being coupled to the membrane, wherein: the loudspeaker basket is coupled airtight to the casing; and the loudspeaker plane is oriented orthogonally to a main emission direction of sound emitted from the loudspeaker and is positioned between the voice coil and a section of the membrane furthermost from the voice coil.

16. A sound generator for mounting on a vehicle to manipulate vehicle noise, the sound generator comprising: a casing; a loudspeaker, the loudspeaker and the casing together enclosing a volume and the loudspeaker extending along a loudspeaker plane; and at least one pressure compensation valve, the pressure compensation valve coupling the volume enclosed by the loudspeaker and the casing with an outside of the casing and the pressure compensation valve extending through the loudspeaker plane, the at least one pressure compensation valve comprising a valve body and a valve head, the valve body having a first end with a first opening formed therein that is open to the outside of the casing, and a second end with a second opening accommodating the valve head, the valve head being disposed inside the volume enclosed by the loudspeaker and the casing, the valve head including a through hole for air, wherein the through hole is always in constant gas communication with the volume enclosed by the loudspeaker and the casing, the first opening and the second opening, the first opening of the valve body being located in the loudspeaker plane, the valve head comprising a valve head interior and a membrane in the valve head interior, the membrane being permeable to gas and impermeable to water and closing the through hole, wherein only gas passes from the valve body and the valve head to the volume enclosed by the loudspeaker and the casing via the through hole.

17. A sound generator according to claim 16, wherein the loudspeaker comprises a loudspeaker basket, at least a portion of the at least one pressure compensation valve penetrating the loudspeaker basket.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1A is a schematic perspective illustration of a sound generator of a system for manipulating sound waves propagating through exhaust systems of vehicles driven by an internal combustion engine according to the prior art;

(3) FIG. 1B is a schematic cross-section through the sound generator of FIG. 1A;

(4) FIG. 2A is a schematic cross-section through a sound generator for mounting on a vehicle to manipulate vehicle noise according to a first embodiment of the invention;

(5) FIG. 2B is a schematic cross-section through a sound generator for mounting on a vehicle to manipulate vehicle noise according to a second embodiment of the invention;

(6) FIG. 2C is a schematic cross-section through a sound generator for mounting on a vehicle to manipulate vehicle noise according to a third embodiment of the invention;

(7) FIG. 3A is a schematically drawn cross-section through a sound generator for mounting on a vehicle to manipulate vehicle noise according to a fourth embodiment of the invention in a first operating condition;

(8) FIG. 3B is a second operation condition of the sound generator of FIG. 3A;

(9) FIG. 3C is a third operation condition of the sound generator of FIG. 3A;

(10) FIG. 3D is a fourth operation condition of the sound generator of FIG. 3A in a view rotated with respect to FIG. 3A;

(11) FIG. 4 is a block diagram of a system for manipulating sound waves propagating through exhaust systems of vehicles driven by an internal combustion engine according to an embodiment of the invention; and

(12) FIG. 5 is a schematic illustration of a motor vehicle having the system of FIG. 4 built-in.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(13) Referring to the drawings, a sound generator according to a first embodiment of the invention is described referencing FIG. 2A. FIG. 2A thereby shows a cross-section through the sound generator 100 in a schematic view.

(14) The sound generator 100 shown in FIG. 2A comprises a casing 110 formed from a lower shell 113 and an upper shell 112 coupled to the lower shell 113 in an airtight manner. Both, the lower shell 113 and the upper shell 112 are made from a stainless steel panel.

(15) The lower shell 113 of the casing 110 includes a casing aperture 111 and receives a bell mouth 140 also made from a stainless steel panel. In the region of the casing aperture 111 an outside of the bell mouth 140 is coupled to the lower shell 113 of the casing 110 in an airtight manner. An opening of the bell mouth 140 is aligned with the casing aperture 111 of the sound generator 100. The bell mouth 140 of the embodiment illustrated is configured for being coupled to an exhaust system as shown in FIG. 1A for a prior art sound generator. The bell mouth 140 is coupled to a loudspeaker basket 123 of a voice coil loudspeaker 120 received in the casing 110 and made from sheet steel in an airtight manner. Accordingly, the loudspeaker basket 123 is coupled to the casing 110 via the bell mouth 140 in an airtight manner.

(16) The voice coil loudspeaker 120 comprises a permanent magnet 121 made from a neodymium iron boron alloy and a non-developable bell mouthed membrane 122 made from synthetic material, both of which are carried by the loudspeaker basket 123. Thereby, the bell mouthed membrane 122 is at the radial outside of its base area coupled to the loudspeaker basket 123 in an airtight manner by an elastic surround 126 (see FIG. 3A) made from synthetic material. The top face of the bell mouthed membrane 122 is centrally sealed by a synthetic material covering cap in an airtight manner. In the region of the covering cap, a voice coil carrier 125 (see FIG. 3A) carrying the voice coil (not shown) is fixed to the membrane 122. The voice coil is positioned in a constant magnetic field generated by the permanent magnet 121. The permanent magnet 121 comprises respective recesses for this. When an alternate current is applied to the voice coil, the voice coil exerts, due to the Lorentz force, a force onto the membrane 122 causing it to oscillate. The current is supplied to the voice coil by means of control lines (only shown in FIG. 1A) passing into the inside of the sound generator 100 through an airtight cable bushing (only shown in FIG. 1A) at the upper shell 122 of the casing 110.

(17) The voice coil loudspeaker 120 and the bell mouth 140 separate a volume 114, that is in fluid communication with an exhaust system via the bell mouth 140 and the casing aperture 111 of the sound generator 100, from a volume 115, that is confined by the upper shell 112 and the lower shell 113 of the casing 110 and also an outside of the bell mouth 114 and in the following referred to as rear volume, in an airtight manner. Accordingly, the voice coil loudspeaker 120 with the bell mouth 123 and the casing 110 together define an enclosed rear volume 115 separated from the atmosphere or the exhaust system by the membrane 122 of the voice coil loudspeaker 120 and a part of the loudspeaker basket 123.

(18) A pressure compensation valve 130 is received inside the casing 110 of the sound generator 100 for enabling a pressure compensation between this enclosed rear volume 115 and the volume 114 at the other side of the membrane 122 of the voice coil loudspeaker 120. The pressure compensation valve 130 is composed of a valve body and a valve head 132. The valve body is not shown for the embodiment of FIG. 2A, since it is an integral part of a housing of the valve head 132. The pressure compensation valve 130 thus penetrates a portion of the loudspeaker basket 123 of the voice coil loudspeaker 120. Hence, the pressure compensation valve 130 extends through the plane in which the membrane 122 of the voice coil loudspeaker 12 is positioned with respect to the casing 110.

(19) The valve head 132 of the pressure compensation valve 130 includes a through hole 135 for air operating like a throttle. A membrane 136 is disposed inside the through hole 135, the membrane being permeable to air and impermeable to water. In the embodiment illustrated, the through hole 135 of the valve head 132 of the pressure compensation valve 130 is dimensioned to allow for a passage of 7.0 liters of air per hour at a constant pressure difference of 300 Pascal between the enclosed rear volume 115 and the volume 114 separated therefrom at the other side of the voice coil loudspeaker 120. The pressure compensation valve 130 is thus too slow to respond to variations in the air pressure generated inside the sound generator 100 by oscillations of the membrane 122 of the voice coil loudspeaker 120. It is noted that the constant pressure difference of 300 Pascal mentioned above is used to determine the flow rate through the pressure compensation valve only; in operation, the pressure difference varies however, and is reduced by the pressure compensation valve 130 continuously.

(20) A second embodiment of the invention is discussed below referencing FIG. 2B. To avoid any repetitions thereby, only differences to the above first embodiment are addressed, and for the rest reference is made to the explanations of the first embodiment.

(21) The sound generator 100 of the second embodiment differs from the sound generator 100 of the first embodiment by the pressure compensation valve 130 comprising a valve body 131 distinct from the valve head 132.

(22) In the embodiment shown, the valve body 131 made in two parts from an elastomer includes a tubing and a barrel. The barrel is in fluid communication with the tubing. At its end facing away from the barrel, the tubing has a first opening 133 penetrating the loudspeaker basket 123 to open into the volume 114. Further, a second opening 134 is formed at the end of the tubing facing away from the barrel that accommodates the valve head 132 and is thus closed by the valve head 132. The through hole 135 formed in the valve head 132 opens into the enclosed rear volume 115. Between the first opening 133 and the second opening 134, the valve body 131 hence comprises a section 137 formed by the barrel (see FIG. 3A) wherein a diameter of the valve head 131 is increased with respect to a diameter of the first opening 133. The valve body 131 thus provides a volume in its interior that amounts, in the embodiment shown, to 5% of the rear volume 115 and enables a compensation of pressure differences between the two sides of the voice coil loudspeaker's 120 membrane 122 even when the sound generator 100 is immersed into water.

(23) In the embodiment illustrated in FIG. 2B, the valve body 131 is configured for the valve head 132 supported by the valve body 131 being positioned at a maximum distance from the plane in which the loudspeaker 120 is disposed at the casing 110 and opposite this plane. As can be seen, the valve head 132 is located in the rear volume 115.

(24) A third embodiment of the invention is discussed below referencing FIG. 2C. To avoid any repetitions thereby, only differences to the above second embodiment are addressed, and for the rest reference is made to the explanations of the second embodiment.

(25) The sound generator 100 according to the third embodiment differs from the sound generator of the second embodiment in that the first opening 133 of the valve body's 131 tubing does not open into the exhaust system but rather into the outside of the casing 110 after penetrating the lower shell 113 of the casing 110. In this embodiment, the valve body 131 therefore allows for a pressure compensation between the rear volume 115 and atmosphere.

(26) In the following, different operating conditions of a sound generator according to a fourth embodiment of the invention are discussed referencing FIGS. 3A to 3D. To avoid any repetitions thereby, only differences to the above second embodiment are addressed, and for the rest reference is made to the explanations of the second embodiment.

(27) The sound generator 100 of the fourth embodiment differs from the sound generator 100 of the second embodiment in that the second opening 134 of the valve body 131 has a diameter bigger than the diameter of the first opening 133 of the valve body 131 but smaller than the diameter of the valve body 131 in the section 137 having an increased diameter/cross-section between the first opening 133 and the second opening 134.

(28) Further, no bell mouth is present inside the casing 110 of the sound generator 100 according to the fourth embodiment, and the casing 110 is also not made in two parts by an upper shell and a lower shell. The casing is rather made cup-shaped from polyvinyl chloride and is sealed by the loudspeaker basket 123 of the voice coil loudspeaker 120 supported by the casing 110. This results in the voice coil loudspeaker 120 separating the rear volume 115 enclosed by the loudspeaker 120 and the casing 110 from the air 114 at the other side of the voice coil loudspeaker 120. Hence, the rear volume 115 communicates also in this case only through the pressure compensation valve 130 with air 114 on the other side of the voice coil loudspeaker 120.

(29) FIG. 3A illustrates a first operating condition, where only air 114 surrounds the sound generator 100. A pressure compensation between the rear volume 115 and the air 114 on the other side of the voice coil loudspeaker 120 through the pressure compensation valve 130 is possible without any problems.

(30) FIG. 3B illustrates a second operating condition, where the sound generator 100 shown in FIG. 3A is partly immersed into water (in the Figure illustrated by wiggly lines). In this case a bubble of compressed air 114 forms in front of the voice coil loudspeaker's 120 membrane 122.

(31) FIG. 3C illustrates a third operating condition, where the sound generator 100 shown in FIG. 3A is completely immersed into water (in the Figure illustrated by wiggly lines). The air, usually contained inside the valve body 131, is pushed by the water having entered into the valve body through the first opening 133 of the valve body 131 almost completely into the rear volume 115 of the casing 110 thereby establishing a pressure compensation between the rear volume 115 and the other side of the voice coil loudspeaker 120 to a certain degree.

(32) FIG. 3D illustrates a fourth operating condition, where the sound generator 100 shown in FIG. 3A is canted into water (in the Figure illustrated by wiggly lines). FIG. 3D thereby shows the sound generator illustrated in FIG. 3A in a view along direction X. As can be seen, the first opening 133 of the valve body 131 is positioned in the tilt axis around which the sound generator 100 is canted.

(33) FIG. 4 shows a schematic diagram of a system 7 for manipulating sound waves propagating through exhaust systems of vehicles driven by an internal combustion engine, the system employing the above sound generator 100.

(34) The sound generator 100 is coupled to an exhaust system 4 in the region of a discharge opening 5 by a Y-pipe 1. Exhaust gas traveling through the exhaust system 4 is discharged from the discharge opening 5 into the exterior together with sound generated by the sound generator 100.

(35) An error microphone 8 in the form of a pressure sensor is provided at the Y-pipe 1. The error microphone 8 measures pressure variations and thus sound inside the Y-pipe 1 in a section downstream of a region, where the sound generator 100 is coupled in fluid communication to the exhaust system 4. It is noted, however, that the error microphone is only optional.

(36) The voice coil loudspeaker 120 of the sound generator 100 and the error microphone 8 are electrically connected to a controller 2. The controller 2 is coupled to an engine controller of an internal combustion engine 6 by a CAN bus. It is noted that the present invention is not limited to a CAN bus.

(37) The exhaust system 4 may further comprise at least one catalytic converter (not shown) located between the internal combustion engine 6 and the Y-pipe 1 for cleaning the exhaust gases emitted from the internal combustion engine 6 that travel through the exhaust system 4.

(38) The general operation of the above system 7 for manipulating sound waves propagating through exhaust systems of vehicles driven by an internal combustion engine is as follows: Using the sound measured by the error microphone 8 and/or operating parameters of the internal combustion engine 6 received via the CAN bus, the controller 2 calculates control signals using a Filtered-x Least Mean Squares (FxLMS) algorithm. The control signals enable a desired manipulation of the sound (exhaust noise) originating from an operation of the internal combustion engine 6 and propagating through the interior of the exhaust system 4 by applying engineered sound produced in the sound generator 100. The controller 2 outputs these control signals via the control lines to the voice coil loudspeaker 120 of the sound generator 100.

(39) Although a system 7 using the sound generator of the first embodiment for manipulating sound waves propagating through exhaust systems of vehicles driven by an internal combustion engine has been described above, alternatively also the sound generator of the second embodiment which is not in fluid communication with the exhaust system may be used.

(40) FIG. 5 shows a schematic illustration of a motor vehicle having an internal combustion engine 6, an exhaust system 4, and the above system 7 for manipulating sound waves propagating through exhaust systems of vehicles driven by an internal combustion engine. The sound generator and the loudspeakers of the anti-noise system are not explicitly shown in FIG. 5.

(41) For the sake of clarity, the Figures show only those elements, components, and functions that are beneficial for the understanding of the present invention. Embodiments of the invention are, however, not limited to the elements, components, and functions shown, but may comprise further elements, components, and functions if necessary for their use or scope of functions.

(42) While the above embodiments of the present invention have been described by way of example only, it is apparent to those skilled in the art that numerous modifications, additions and substitutions can be made without departing from the scope and gist of the invention disclosed in the following claims. While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.