EP4601319A1

EP4601319A1 - Vehicle loudspeaker system and vehicle structure comprising such loudspeaker system

Info

Publication number: EP4601319A1
Application number: EP24156361.8A
Authority: EP
Inventors: Rolf-Sebastian Bothe; Masaru Yamagami; Cengiz Kizilbagli
Original assignee: Alps Alpine Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 2024-02-07
Filing date: 2024-02-07
Publication date: 2025-08-13

Abstract

A vehicle loudspeaker system (1) comprises a first loudspeaker device (10) with a first driver (11), a first housing (12) and a first diaphragm (13), and which is configured to emit sound from a first side (131) of the first diaphragm (13) to an inner space (IS) of the vehicle, and a second loudspeaker device (20) with a second driver (21), a second housing (22) and a second diaphragm (23), and which is configured to emit sound from a first side (231) of the second diaphragm (23) to an outside space (OS) of the vehicle. A communication channel (30) is coupled to the first and second housing (12, 22) for communicating back sound between the second side (132) of the first diaphragm (13) and the second side (232) of the second diaphragm (23) and comprises a first terminal (31) communicating with the back space (15) of the first loudspeaker device (10) and a second terminal (32) communicating with the back space (25) of the second loudspeaker device (20). The communication channel (30) is adapted to be coupled to or arranged in a through-opening (70) of a partition panel (80) dividing the inner space (IS) from the outside space (OS) of the vehicle. The vehicle loudspeaker system is capable of improving noise vibration harshness (NVH) behavior through a porthole in a vehicle partition panel without or with less decreasing the acoustical performance and/or efficiency of the loudspeaker system as compared to a single "fresh air" speaker system.

Description

The present invention relates to a vehicle loudspeaker system comprising a loudspeaker device having a driver and a diaphragm, and which is configured to emit front sound from a first side of the diaphragm to an inner space of the vehicle, and comprises a communication channel communicating with a back space of the diaphragm facing a second side of the diaphragm opposite the first side, and which is adapted to be coupled to an opening of a partition panel dividing the inner space from an outside space of the vehicle for communicating back sound emitted from the second side of the diaphragm away from the inner space of the vehicle.
In the automotive field, loudspeaker devices are commonly used for providing audio output or sound to listeners situated in vehicles like cars. A loudspeaker device typically employs a magnetic driving unit causing a diaphragm connected to a frame of the loudspeaker device to move back and forth. This vibration creates sound that is produced by the loudspeaker and emitted towards an inside space of the vehicle. The frame is commonly enclosed by a housing of the loudspeaker device. When the loudspeaker device is a subwoofer, for example, typically an air communication duct connects a back space of the diaphragm to an outside space of the vehicle.
In known arrangements, for example, such loudspeaker device is installed at a vehicle panel (such as part of a vehicle body) which has a separate opening to an outside space of the vehicle. The loudspeaker device comprises a housing including an air volume which is communicated at a backside of the diaphragm through an air communication duct and the opening with the outside space of the vehicle. Such arrangement enables the loudspeaker device to be placed in small locations such as in a vehicle side space adjacent to a vehicle panel or in the rear part near the trunk.
EP 2 658 280 A1 discloses a speaker device which includes a cabinet from which a duct for adjusting the back pressure protrudes, a speaker unit mounted in the cabinet, and an intermediate hollow member including a first and second connection portions. A cabin space in which the cabinet is installed is separated from a non-cabin space by a partition wall. Because there is a subframe facing the partition wall, the duct cannot be directly connected to the opening formed in the partition wall. The intermediate hollow member is disposed in a small space between the subframe and the partition wall, wherein the second connection portion is connected to the opening and the duct is connected to the first connection portion.
WO 2011/047435 A1 discloses a loudspeaker assembly for use in a loudspeaker system having infinite baffle topology. The assembly comprises a driver including a cone and a basket and at least one Helmholtz resonator including a chamber and a vent duct communicating with the chamber and adapted to pass through the infinite baffle. The chamber is dimensioned to provide a tuned frequency well above an operating band associated with the driver. The cross sectional area and length of the vent duct may be set to provide control over duct air noise and low frequency extension.
For connecting the air communication duct as described above to the outside, an opening, such as a porthole, needs to be provided in the vehicle panel, which may form part of the vehicle body and may be, for example, a front firewall of the vehicle. Typically, such opening is a dedicated hole in a vehicle structure, such as a vehicle panel, which may cause additional noise to enter the vehicle. Typically, a front firewall is a very solid welded frame assembly which is covered by damping materials to dampen noise and vibrations from a motor compartment and achieve good so-called noise vibration harshness (NVH). The opening in the vehicle panel, however, is weakening such NVH behavior.
Generally, NVH behavior is of a big concern for automotive manufacturers. In this regard, loudspeaker systems installed in a front vehicle panel, such as the front firewall, are rated much more critical because of the increased noise and vibration transfer function. In some cases, vehicle loudspeaker systems could be optimized for good NVH behavior, such as with integrated damping, absorption, and/or additional top cover, but this will typically imply negative impact in regards to acoustical performance, sensitivity and efficiency.
For example, in some implementations, acoustical performance on such loudspeaker system is inversely proportional to the measures integrated for optimizing NVH behavior (simply spoken: all damping and absorption measures could be seen as a mass increase which is counterproductive for good acoustical speaker performance). Above that, typically the range around system resonance is transparent for noise and could not be improved by standard damping or absorption measures.
It is therefore an object of the present invention to provide a vehicle loudspeaker system of the type as mentioned above, which is capable of improving NVH behavior through an opening in a vehicle partition panel without or with less decreasing the acoustical performance and/or efficiency of the loudspeaker system.
The invention relates to a vehicle loudspeaker system according to the appended claims. Moreover, the invention relates to a vehicle structure, and to a vehicle comprising such vehicle structure. Embodiments are disclosed in the dependent claims.
According to a first aspect, there is disclosed a vehicle loudspeaker system comprising a first loudspeaker device having a first driver, a first housing and a first diaphragm and which is configured to emit sound from a first side of the first diaphragm to an inner space of the vehicle, wherein the first housing surrounds at least part of a first back space of the first diaphragm facing a second side of the first diaphragm opposite the first side of the first diaphragm, and a second loudspeaker device having a second driver, a second housing and a second diaphragm and which is configured to emit sound from a first side of the second diaphragm to an outside space of the vehicle, wherein the second housing surrounds at least part of a second back space of the second diaphragm facing a second side of the second diaphragm opposite the first side of the second diaphragm. A communication channel is coupled to the first and second housing for communicating back sound between the second side of the first diaphragm and the second side of the second diaphragm and comprises a first terminal communicating with the first back space and a second terminal communicating with the second back space, wherein the communication channel is adapted to be coupled to or arranged in a through-opening of a partition panel dividing the inner space from the outside space of the vehicle.
With provision of such loudspeaker system, it is possible to improve in a loudspeaker system of the type as mentioned above NVH behavior through an opening or porthole in a vehicle partition panel without or with less decreasing the acoustical performance and/or efficiency of the loudspeaker system. Particularly, NVH behavior could be optimized without decreasing the acoustical performance / efficiency. NVH behavior may be improved especially around the loudspeaker system resonance frequency, where typically the range around the system resonance frequency is transparent for noise and could not be improved by standard damping or absorption measures as described above. With provision of a loudspeaker configuration with coupled first and second loudspeakers, as described herein according to aspects of the invention, noise must pass two times the loudspeakers' soft parts (and air volume in between) before it reaches the inside space of the vehicle. Hence, transmission loss of noise will be increased significantly, but without mass increase by any added damping measures, thus improving NVH behavior through a porthole in a vehicle partition panel where the communication channel for communicating backsound is guided through. According to aspects of the invention, with the coupled first and second loudspeaker devices, impedance behavior for the coupled loudspeaker system is generally the same as for a single loudspeaker device configured to emit front sound to an inner space of the vehicle and with a communication channel communicating with a back space of the diaphragm and communicating back sound to the outside of the vehicle.
According to an embodiment, the communication channel is attached to at least one of a side wall of the first housing and side wall of the second housing.
According to an embodiment, the communication channel comprises at least one tube connecting the first housing and the second housing.
In an embodiment of the invention, the vehicle loudspeaker system comprises at least one amplifier, wherein the first driver and the second driver are electrically coupled to the at least one amplifier at opposite poles. Particularly, the first driver and second driver for driving the respective first and second diaphragms are electrically coupled or wired counter wise or out of phase, that is at a phase of approximately 180°, so that movements of the first and second diaphragms are counter wise to one another (i.e. move in a same direction to the left or right) For example, when the first diaphragm moves forward, the second diaphragm moves backward and vice versa. In consequence, the communication chamber or channel operates at a pressure which is the same on both sides on the first and second diaphragms, i.e. at isobaric pressure.
According to an embodiment, the at least one amplifier comprises an output stage having a first channel and a second channel. The first driver is coupled with the first channel and the second driver is coupled with the second channel.
According to another embodiment, the first driver and the second driver are coupled with the at least one amplifier in parallel.
According to another embodiment, the first driver and the second driver are coupled with the at least one amplifier in series.
Preferably, the first and second loudspeaker devices are configured such that the respective diaphragms vibrate at a frequency in a sub-woofer frequency range.
According to embodiments, the two loudspeaker devices can be of same or different sizes and/or power configuration, e.g., can comprise diaphragms having same or different diameters and/or drivers having same or different power or impedance characteristics. In a preferred embodiment, the first and second loudspeaker devices have a substantially same impedance-frequency-characteristic. In an embodiment, the first and second loudspeaker devices have a same impedance-frequency-characteristic.
According to another aspect, the invention also relates to a vehicle structure comprising a partition panel dividing an inner space from an outside space of the vehicle, a through-opening formed in the partition panel, and a vehicle loudspeaker system as described herein, wherein the first loudspeaker device is arranged at a first side of the partition panel, particularly an inner space of the vehicle, and the second loudspeaker device is arranged at a second side of the partition panel which is opposite the first side of the partition panel, particularly an outside space of the vehicle, such as a trunk at the front or rear of the vehicle, an engine compartment or a space between an inner skin and outer skin of a door. At least part of the communication channel is arranged in the through-opening of the partition panel.
According to an embodiment, the communication channel comprises a first tube and a second tube connecting the first housing and the second housing, wherein the first tube is attached to the first side of the partition panel and the second tube is attached to the second side of the partition panel. In this way, two loudspeaker devices may be attached to a respective side of the partition panel, such as by suitable attachment means, and the communication channel is formed by the first and second tubes and the through-opening in the partition panel.
According to an embodiment, the partition panel forms an outer skin portion of a vehicle body.
According to another aspect, the invention also relates to a vehicle comprising such vehicle structure according to aspects of the invention as described herein.
Aspects and embodiments of the invention will now be described with reference to the drawings, in which:

Fig. 1: shows a vehicle loudspeaker system and a vehicle structure according to an embodiment of the invention,
Fig. 2A - 2C: show a respective vehicle loudspeaker system and a vehicle structure according to embodiments of the invention,
Fig. 3: shows an exemplary diagram of an impedance-frequency-characteristic of a loudspeaker system according to Fig. 2C compared to an exemplary loudspeaker system according to existing practice in which a single loudspeaker device is configured to emit front sound to an inner space of the vehicle and with a communication channel communicating with a back space of the diaphragm and communicating back sound to the outside of the vehicle through a porthole in the vehicle partition panel.

Fig. 1 shows a vehicle loudspeaker system and a vehicle structure according to an embodiment of the invention. The vehicle structure 2 comprises a vehicle partition panel 80 that separates an inner space IS and an outer space OS of a vehicle, such as an automobile or car. For example, the inner space IS is a passenger compartment or any other space inside the vehicle chassis. For example, the inner space IS is or has access to a vehicle interior space in which the driver and any passengers are travelling. In the present embodiment, the inner space IS is an acoustic space into which sound is radiated from a first loudspeaker device 10. The outside space OS may be an exterior space of the vehicle, or, for example, a trunk or engine compartment with direct or indirect fresh air access. For example, the partition panel 80 forms an outer skin portion of the vehicle body.
The first loudspeaker device 10 is fixed to the vehicle partition panel 80 and comprises a first frame 14, a first diaphragm 13 elastically supported at the frame 14, and a first driving device 11 (simply designated as first driver 11) that is configured to provide driving power for operating the diaphragm 13. A first housing 12 is attached to the frame 14 such that a first back space 15 of the diaphragm 13 is enclosed between the diaphragm 13 and the housing 12. The diaphragm 13 is configured to emit front sound from a first side 131 of the diaphragm 13 towards the inner space IS of the vehicle. For example, the loudspeaker device 10 is configured such that the diaphragm 13 vibrates at a frequency in a sub-woofer frequency range. The diaphragm 13 has a cone shape and is supported by an outer circumferential portion of the frame 14, wherein in the present embodiment the convex side of the diaphragm 13 forms a second side 132 of the diaphragm 13 opposite the first side 131. In principle, another arrangement with housing 12 attached to the frame 14 on the concave side of the diaphragm 13 would also be possible. The back space 15 of the diaphragm 13, which is preferably a closed space, faces the second side 132 of the diaphragm 13.
Similarly, a second loudspeaker device 20 is fixed to an opposite side of the vehicle partition panel 80 and comprises a second frame 24, a second diaphragm 23 elastically supported at the frame 24, and a second driving device 21 (simply designated as second driver 21) that is configured to provide driving power for operating the diaphragm 23. A second housing 22 is attached to the frame 24 such that a second back space 25 of the diaphragm 23 is enclosed between the diaphragm 23 and the housing 22. The diaphragm 23 is configured to emit front sound from a first side 231 of the diaphragm 23 towards the outside space OS of the vehicle. For example, the loudspeaker device 20 is configured such that the diaphragm 23 vibrates at a frequency in a sub-woofer frequency range. The diaphragm 23 has a cone shape and is supported by an outer circumferential portion of the frame 24, wherein in the present embodiment the convex side of the diaphragm 23 forms a second side 232 of the diaphragm 23 opposite the first side 231. In principle, another arrangement with housing 22 attached to the frame 24 on the concave side of the diaphragm 23 would also be possible. The back space 25 of the diaphragm 23, which is preferably a closed space, faces the second side 232 of the diaphragm 23.
A communication channel 30 is coupled to the first and second housings 12 and 22 for communicating back sound between the second side 132 of the diaphragm 13 and the second side 232 of the diaphragm 23. The communication channel 30 comprises a first terminal 31 communicating with the first back space 15 and a second terminal 32 communicating with the second back space 25. The communication channel 30 is adapted to be coupled to or arranged in a through-opening 70 of the partition panel 80, such as a porthole, which divides the inner space IS from the outside space OS of the vehicle.
According to an embodiment, the communication channel 30 is attached to at least one of a side wall of the first housing 12 and a side wall of the second housing 22. In a further embodiment, the communication channel 30 comprises at least one tube 35 connecting the first housing 12 and the second housing 22. For example, the at least one tube 35 is formed by a first tube 351 and a second tube 352, or is formed by a single tube 35 which is arranged in the through-opining 70.
According to an embodiment, the two loudspeaker devices 10, 20 may be attached to a first side 801 and second side 802, respectively, of the partition panel 80 by suitable attachment means, such as screws from each respective side, and the communication channel 30 is formed by respective first and second tubes 351, 352 and the through-opening 70 in the partition panel 80. According to another embodiment, the tubes 351, 352 are inserted into one another (as schematically shown in Fig. 1), wherein one of the tubes 351, 352 or both are arranged in the through-opening 70, so that the communication channel 30 is formed by the first and second tubes 351, 352.
With the communication channel 30, back sound emitted from the second side 132 of the diaphragm 13 of the first loudspeaker device 10 is communicated away from the inside space IS of the vehicle through the communication channel 30 and the opening 70 in partition panel 80 towards the second loudspeaker device 20, particularly its back space 25. Since the diaphragm 23 of the second loudspeaker device 20 is moving out of phase or counter wise in relation to the diaphragm 13 of the first loudspeaker device 10, the acoustic impedance characteristic is similar to an arrangement in which a single loudspeaker device, such as loudspeaker device 10, emits front sound to the inner space IS of the vehicle and a communication channel, such as communication channel 30, communicates back sound directly to the outside space OS of the vehicle with direct or indirect fresh air access through an opening in the vehicle partition, such as opening 70.
Fig. 2A-2C show a respective vehicle loudspeaker system and a vehicle structure according to embodiments of the invention. In all embodiments shown in Fig. 2A-2C, the vehicle loudspeaker system comprises one or more amplifiers 40, which comprises an output stage 41 for driving the diaphragms 13 and 23, respectively. For example, the drivers 11 and 21 comprise respective coils 111 and 211 which are part of respective magnetic circuits of the drivers 11 and 21, as commonly known. The output stage 41 of the amplifier 40 is coupled to the respective coils 111 and 211. In order for the diaphragms to move out of phase or counter wise, the driver 11 and the driver 21 are coupled to the output stage 41 of the amplifier 40 at opposite poles, such that the positive and negative poles are coupled to the output stage 41 in inverted manner.
According to Fig. 2A, the output stage 41 has a first channel CH1 and a second channel CH2. The driver 11 is coupled with the first channel CH1 and the driver 21 is coupled with the second channel CH2. According to Fig. 2B, the drivers 11 and 21 are coupled with the amplifier 40 in parallel, and according to Fig. 2C the drivers 11 and 21 are coupled with the amplifier 40 in series, thus forming a respective 1-channel connection.
According to an embodiment, the working range of the vehicle loudspeaker system is in the subwoofer range, particularly in a range equal to or below approx. 50-150 Hz.
Fig. 3 shows an exemplary diagram of an impedance-frequency-characteristic of a loudspeaker system according to embodiments of the invention as shown, e.g., in Fig. 2C (curve 101: "both driver coupled both connected (in series)") compared to an exemplary loudspeaker system according to existing practice in which a single loudspeaker device ("single fresh air speaker"), such as loudspeaker device 10, emits front sound to the inner space IS of the vehicle and a communication channel, such as communication channel 30, communicates back sound directly to the outside space OS of the vehicle with direct or indirect fresh air access through an opening in the vehicle partition 80, such as opening 70 (curve 102: "one driver installed"). As can be seen from the impedance-frequency-characteristics, the impedance behavior for the coupled loudspeaker system 1 is showing a characteristic which is generally the same as for a single fresh air speaker. Particularly, the impedance peak is at a similar resonance frequency than with a single fresh air speaker. Further advantageously, noise from outside space OS must pass two times the soft parts of the loudspeaker system 1, such as the diaphragms 23 and 13, before it reaches the inside space IS, so the transmission loss of noise through the loudspeaker system 1 is increased.

Claims

A vehicle loudspeaker system (1), comprising
a first loudspeaker device (10) comprising a first driver (11), a first housing (12) and a first diaphragm (13), and which is configured to emit sound from a first side (131) of the first diaphragm (13) to an inner space (IS) of the vehicle, wherein the first housing (12) surrounds at least part of a first back space (15) of the first diaphragm (13) facing a second side (132) of the first diaphragm (13) opposite the first side (131) of the first diaphragm (13),

a second loudspeaker device (20) comprising a second driver (21), a second housing (22) and a second diaphragm (23), and which is configured to emit sound from a first side (231) of the second diaphragm (23) to an outside space (OS) of the vehicle, wherein the second housing (22) surrounds at least part of a second back space (25) of the second diaphragm (23) facing a second side (232) of the second diaphragm (23) opposite the first side (231) of the second diaphragm (23), and

a communication channel (30) coupled to the first and second housing (12, 22) for communicating back sound between the second side (132) of the first diaphragm (13) and the second side (232) of the second diaphragm (23) and comprising a first terminal (31) communicating with the first back space (15) and a second terminal (32) communicating with the second back space (25),

wherein the communication channel (30) is adapted to be coupled to or arranged in a through-opening (70) of a partition panel (80) dividing the inner space (IS) from the outside space (OS) of the vehicle.
The vehicle loudspeaker system according to claim 1, wherein the communication channel (30) is attached to at least one of a side wall of the first housing (12) and a side wall of the second housing (22).
The vehicle loudspeaker system according to claim 1 or 2, wherein the communication channel (30) comprises at least one tube (35) connecting the first housing (12) and the second housing (22).
The vehicle loudspeaker system according to one of claims 1 to 3, further comprising at least one amplifier (40), wherein the first driver (11) and the second driver (21) are coupled to the at least one amplifier (40) at opposite poles.
The vehicle loudspeaker system according to claim 4, wherein the at least one amplifier (40) comprises an output stage (41) having a first channel (CH1) and a second channel (CH2), wherein the first driver (11) is coupled with the first channel (CH1) and the second driver (21) is coupled with the second channel (CH2).
The vehicle loudspeaker system according to claim 4, wherein the first driver (11) and the second driver (21) are coupled with the at least one amplifier (40) in parallel.
The vehicle loudspeaker system according to claim 4, wherein the first driver (11) and the second driver (12) are coupled with the at least one amplifier (40) in series.
A vehicle structure (2), comprising
a partition panel (80) dividing an inner space (IS) from an outside space (OS) of the vehicle,

a through-opening (70) formed in the partition panel (80), and

a vehicle loudspeaker system (1) according to one of the preceding claims, wherein the first loudspeaker device (10) is arranged at a first side (801) of the partition panel (80) and the second loudspeaker device (20) is arranged at a second side (802) of the partition panel (80) which is opposite the first side (801) of the partition panel (80), and at least part of the communication channel (30) is arranged in the through-opening (70) of the partition panel (80).
The vehicle structure according to claim 8, wherein the communication channel (30) comprises a first tube (351) and a second tube (352) connecting the first housing (12) and the second housing (22), wherein the first tube (351) is attached to the first side (801) of the partition panel (80) and the second tube (352) is attached to the second side (802) of the partition panel (80).
A vehicle comprising a vehicle structure (1) according to claim 8 or 9.