Sound generation device for applications in an AVAS vehicle

Abstract

Sound generating device (1) for applications in an AVAS vehicle, comprising a two-part housing (3, 5) in which a loudspeaker (11) for outputting an acoustic signal and a signal frequency extension unit are positioned, wherein the loudspeaker (11) is arranged in a first housing part (3) whose protective grille in front of the loudspeaker diaphragm (13) is in direct contact with the environment of the vehicle, and the first housing part (3) is covered with a second housing part (5), characterized in that the signal frequency extension unit (15, 33) is positioned on the first housing part (3) next to the loudspeaker (11) arranged in an opening (17) of the first housing part (3) and is covered by the protective grille (21) for direct contact with the environment of the vehicle, and the signal frequency extension unit is designed as a helical or spiral channel (15),wherein the channel (15) has an open channel outlet (19) to the outside of the first housing part (3) and a structure of the helical channel (15) extends in a main forming direction of the first housing part (3).

Description

[0001] The invention relates to a sound generation device for applications in an AVAS vehicle, comprising a two-part housing in which a loudspeaker for outputting an acoustic signal and a signal frequency extension unit are positioned, wherein the loudspeaker is arranged in a first housing part and a protective grille of a loudspeaker diaphragm is in direct contact with the environment of the vehicle, and the first housing part is covered with a second housing part.

[0002] In low-noise vehicles, such as electric and hybrid vehicles, an Acoustic Vehicle Alerting System (AVAS) is used to emit an artificially generated sound to warn other road users. This sound is similar to that of a combustion engine. It is common practice to use a loudspeaker box designed as a closed enclosure. In this case, the enclosed, acoustically effective volume acts as an air spring and resonance chamber. The sound reproduction characteristics of a loudspeaker box are determined by measuring the sound pressure level (SPL) across a range of frequencies. This results in a lower cutoff frequency, which depends on both the loudspeaker characteristics and the acoustically effective volume.For example, with an acoustic volume of 40L in a closed box, the lower cutoff frequency could be 60 Hz, and with an acoustic volume of 4L, the lower cutoff frequency could be 100 Hz. However, due to the limited installation space in a vehicle, the acoustically effective volume of the speaker box is severely restricted, which usually results in the low frequencies of the signal being limited to a lower cutoff frequency of > 100 Hz.

[0003] From DE 10 2020 112 680 A1, a noise simulator for a motor vehicle is known, which has a housing consisting of two chambers. In the first chamber, a loudspeaker is positioned, directed outwards towards the vehicle's surroundings. In the second chamber, a structure-borne sound transducer is mounted directly on the housing. A tube, which amplifies the low-frequency sound waves of the loudspeaker, is arranged such that its sound outlet to the surroundings is located in the second chamber.

[0004] GB 2 344 016 A discloses an ABR loudspeaker that utilizes empty spaces within the vehicle to create a closed air box. Such empty spaces include, for example, glove compartments, doors, and the like, forming enclosed air volume boxes for "active" loudspeakers in combination with passive elements such as passive radiators. This arrangement increases the loudspeaker's efficiency in the low-frequency range.

[0005] From DE 10 2004 016 282 A1, a loudspeaker unit is known in which at least one bass loudspeaker and at least one bass reflex tube are arranged. Such loudspeaker units are installed in the vehicle interior or the trunk of the vehicle, with the sound entering the vehicle interior through air vents. To prevent the ingress of foreign objects into the loudspeaker unit, the loudspeaker unit is equipped with a foreign object ingress protection device. For this purpose, for example, a plastic grille with a large mesh size is stretched over the diaphragm opening on the side of the bass loudspeaker facing the vehicle interior.

[0006] DE 20 2017 005 756 U1 discloses a helical loudspeaker which, as a transducer system, incorporates an acoustic waveguide formed in a spiral shape as a single-piece snail, tapering in cross-sectional area from the entrance to the rear end. This special design of the loudspeaker box achieves deep bass reproduction.

[0007] US 5824969 describes a loudspeaker assembly comprising a three-dimensional spiral sound channel formed by a coaxial double-tube structure consisting of an outer tube and an inner tube, as well as a spiral baffle. The spiral baffle bridges a gap between the outer and inner tubes before the sound wave exits the loudspeaker assembly.

[0008] From the JP2010-178323A, a loudspeaker is known which comprises a separate driver side and a passive radiator side, each for which a separate enclosure is provided. Both enclosures are connected to each other by a tube.

[0009] US Patent 2023 / 0269505 A1 discloses a loudspeaker unit for exterior vehicle applications, comprising a loudspeaker, a bass unit, and a grille opening in which a grille for covering the loudspeaker is arranged. The loudspeaker unit has a two-part housing within which the loudspeaker and the signal frequency extension unit are integrated.

[0010] The object of the invention is to provide a sound generation device for AVAS applications in a vehicle which, despite low design complexity, can be used for a large number of vehicle series from a vehicle manufacturer.

[0011] The invention is defined by the features of the independent claim. Advantageous further developments and embodiments are the subject of the dependent claims. Further features, applications, and advantages of the invention will become apparent from the following description and the explanation of exemplary embodiments of the invention illustrated in the figures.

[0012] The problem is solved by the subject matter of claim 1.

[0013] The proposed sound generation device for AVAS applications in a vehicle comprises a two-part housing in which a loudspeaker for outputting an acoustic signal and a signal frequency extension unit are positioned, wherein the loudspeaker is arranged in a first housing part and a protective grille of the loudspeaker diaphragm is in direct contact with the environment of the vehicle, and the first housing part is covered with a second housing part.The signal frequency extension unit is positioned on the first housing part next to the loudspeaker, which is located in an opening in the first housing part, and is covered by the protective grille for direct connection to the vehicle's environment. The signal frequency extension unit is designed as a helical or spiral channel, with an open channel outlet on the outside of the first housing part. The structure of the helical channel extends in a main direction of the first housing part. When assembled, the first and second housing parts form the total volume necessary for sound generation. The first housing part contains all the active components necessary for sound generation, such as the loudspeaker and the signal frequency extension unit for the loudspeaker.Since the first housing part is the same for all vehicle series of a vehicle manufacturer, cost-effective production of the sound generation device in large quantities is possible, which reduces manufacturing costs.

[0014] In such a ventilated enclosure design, the acoustically effective volume is not sealed off from the vehicle's surroundings, but rather opened to the environment via the duct outlet. The duct is characterized by a cross-sectional area and a duct length, which together form the resonant air column oscillating within the duct. Depending on the overall system, including loudspeaker characteristics, acoustically effective volume, and duct properties, a system resonance is achieved for the ventilated system. This allows the lower cutoff frequency set by the loudspeaker to be shifted to lower frequencies, or an additional sound pressure boost to be achieved in a low-frequency range below the cutoff frequency. This makes it possible to add emotional depth to event sounds, such as a welcome sound, thereby enhancing the overall impression of the vehicle.

[0015] To minimize acoustic flow noise, it is necessary to limit the air velocity within the duct. This can be achieved by maximizing the cross-sectional area. However, the required duct length is directly dependent on the cross-sectional area and the system resonance of the overall ventilating system. The larger the cross-sectional area, the greater the required duct length to achieve the same system resonance. If, for example, the duct diameter is chosen to be 4.5 cm to minimize acoustic flow noise, very long duct lengths in the range of approximately 20 to 45 cm may be required to achieve a low system resonance frequency, for example, in the range between 50 and 70 Hz.

[0016] The spiral or helical design makes it particularly advantageous to achieve such very long duct lengths for a low system resonance frequency while simultaneously reducing installation space. This is also guaranteed when limiting the duct's cross-sectional area to prevent acoustic flow noise caused by the velocity of the air flowing through the duct. Thus, duct length and cross-sectional area can be optimally matched to each other within the constraints of the installation space.

[0017] The signal frequency extension unit's length and radial base, relative to the first housing part, minimize the required installation space and integrate the necessary channel length into the housing as compactly as possible. To manufacture this first housing part containing the channel, plastic is injected into a mold. This mold is milled to match the housing part and has clearances in the areas where the wall thickness of the housing part being molded is present. After the injection molding process, the mold opens, and the housing part can be removed. This opening direction of the mold relative to the housing part is called the primary demolding direction.

[0018] In a further embodiment, the signal frequency expansion unit is an integral part of the first housing component. Since the first housing component is preferably made of a plastic, it can be manufactured together with the signal frequency expansion unit in a single forming process, which further reduces costs.

[0019] In a further embodiment, the open channel outlet is covered with a grille, which is preferably an integral part of the first housing part. Such a protective grille prevents the ingress of foreign particles and / or rodents. The protective grille can also be manufactured in a single step together with the first housing part and the signal frequency extension unit, further reducing assembly effort.

[0020] In another embodiment, the spiral or helical channel is sealed at the rear with a gasket. This gasket can simultaneously serve as tolerance compensation. A simple design for the gasket is a cover bonded to the signal frequency extension unit. Alternatively, the use of a foam material as a gasket is conceivable, whereby the foam material can be applied to the rear of the spiral or helical channel.

[0021] In a further embodiment, the spiral or helical channel is closed off at the rear by the second housing part. An additional seal, for example in the form of the aforementioned foam material, can be arranged between the second housing part and the signal frequency extension unit.

[0022] In a further embodiment, at least one drainage structure is formed on the front surface of the first housing part facing the environment. To allow water that has entered the sound-generating device to drain away directly, the first housing part is open with this drainage structure. This allows the water to drain even when the sound-generating device is positioned horizontally. If the front of the sound-generating device is not horizontally oriented, the drainage structure can be located at the lowest point.

[0023] In a further embodiment, the at least one drainage structure is filled with a coarse noise-absorbing material. Such a material, for example a foam, can prevent airborne noise within the drainage structure. Furthermore, it is conceivable to cover the at least one drainage structure filled with the coarse noise-absorbing material with an additional lid.

[0024] In another embodiment, the signal frequency extension unit is designed as a passive radiator, positioned within the enclosure, which is completely sealed by the first and second housing sections. With this enclosure design, the acoustically effective volume is enclosed within the housing. The passive radiator, used in addition to the loudspeaker, is set into vibration by the pressure differences within the enclosure. These pressure differences arise from the vibrations radiated into the interior of the enclosure by the loudspeaker. Challenges related to water drainage, seals, or environmental conditions, such as the potential ingress of foreign particles, rodents, etc., do not need to be considered with such a closed system.

[0025] Further advantages, features, and details will become apparent from the following description, in which at least one embodiment is described in detail. The described features can, individually or in any meaningful combination, constitute the subject matter of the invention, optionally also independently of the claims, and can, in particular, also be the subject matter of one or more separate applications.

[0026] This shows: Fig. 1 a first embodiment of the sound-generating device according to the invention, Fig. 2 an interior view of the first housing part of the sound-generating device according to Fig. 1, Fig. 3 a front view of the first housing part of the sound-generating device according to Fig. 1, Fig. 4 a second embodiment of the sound-generating device according to the invention.

[0027] In Fig. Figure 1 shows a first embodiment of the sound generation device 1 according to the invention, which is used in low-noise vehicles, such as electric or hybrid vehicles, to artificially generate an engine noise to warn other road users. The sound generation device 1 has a housing consisting of two housing parts 3, 5, which are shell-shaped and lie on top of each other along their circumferential edges 7, 9, thus covering each other. A protective grille 21 projects from the lower first housing part 3, which is in direct contact with the vehicle's surroundings. In addition to the loudspeaker, a signal frequency extension unit is integrated into the first housing part 3. The design of the signal frequency extension unit is explained in more detail with reference to the following figures. All active components for sound generation are positioned on the first housing part 3, and it has a vehicle-series-neutral shape.The second housing part 5, which covers the first housing part 3 and is designed as a rear shell, serves, with regard to its shape, to provide a vehicle-series-specific acoustic sub-volume. The shape of the second housing part 5 is adapted to the installation space requirements of the respective vehicle series. The first and second housing parts 3, 5 form a total volume for acoustic sound generation.

[0028] Fig. Figure 2 shows an interior view of the first housing part 3 of the sound-generating device 1, which, after the assembly of the two housing parts 3, 5, points into the interior of the sound-generating device 1. The figures show Fig. 2a a top view and Fig. 2b, c a perspective view. The first housing part 3 includes a central opening 17 for receiving the loudspeaker 11, with the loudspeaker 11 in Fig. 2 is not shown. Next to this opening 17, the signal frequency extension unit, designed as a helically winding channel 15, is integrated into the first housing part 3, the structure of which extends in a main shaping direction of the first housing part 3 ( Fig. 2c). A helically winding channel 15 can also be understood as a snail-shaped channel or a spirally shaped channel. This channel 15 is characterized by its length and its cross-sectional area, which define the oscillating resonant air column.

[0029] Depending on the characteristics of the loudspeaker 11 and the volume enclosed by the housing parts 3, 5, as well as the resonant air column, a system resonance results for the ventilating system. Depending on the design, the lower cutoff frequency range can be shifted to lower frequencies, or a sound pressure below this cutoff frequency can be amplified in a limited range. A direct connection of the duct 15 to the vehicle environment is established via an open channel outlet 19 in the first housing part 3. Such a housing 3, 5 constitutes a ventilating housing. The channel outlet 19 of the ventilating housing 3, 5 is covered externally by a grille 21. The rear closure of the duct 15 is formed by a seal 23 ( Fig. 2d). This seal 23 can be implemented by the second housing part 5. An additional foam can be introduced into this area of ​​the second housing part 5 (not shown) to compensate for tolerances and provide further sealing.

[0030] A front view of the first housing part 3 of the sound-generating device 1 according to Fig. 1 is shown in Fig. 3, wherein Fig. 3a a direct top view and Fig. Figure 3b shows a perspective view. The grid 21, which closes the channel outlet 19 of the spirally shaped channel 15, is, like the channel 15, an integral part of the first housing part 3 and forms the outer closure of the channel 15, with the grid 21 protruding from the first housing part 3.

[0031] Fig. 3c and Fig. The 3D figures show an external view of the first housing part 3 with a first and second water drainage structure 25, 27, respectively. The first water drainage structure 25 is integrated directly into the first housing part 3, for example, in a lower left corner, and the second water drainage structure 27 is integrated directly into the first housing part 3, for example, in a lower right corner. The first housing part 3 is open at these points to these first and second water drainage structures 25, 27.

[0032] According to Fig. 3d The first and second water drainage structures are each provided with a first and second cover 29, 31 and are filled internally with a coarse noise-reducing material (not shown), e.g., foam, to prevent air noise. The noise-reducing material, e.g., foam, is intended as a replacement part during maintenance intervals (if necessary, over the vehicle's service life). The loudspeaker 11 is characterized by a protective grille 13 located in front of the loudspeaker diaphragm, which faces directly into the environment.

[0033] In Fig.Figure 4 shows a second embodiment of the sound-generating device 1 according to the invention. In addition to the loudspeaker 11, an additional passive diaphragm 33 is arranged on the inside of the first housing part 3. This diaphragm is excited to vibrate by the pressure differences in the housing 3, 5. The acoustically effective volume enclosed by the two housing parts 3, 5 is closed. The passive diaphragm 33 is characterized by its diaphragm area, vibrating mass, stiffness, and maximum diaphragm excursion. Depending on the overall system, a system resonance occurs at which the passive diaphragm 33 vibrates resonantly and amplifies the sound pressure accordingly, thereby generating low frequencies. Reference symbol list 1 Sound generating device first housing part 3 5 second housing part 7 first circumferential edge 9 second circumferential edge 11 speakers 13 Protective grilles in front of the loudspeaker diaphragm 15 Channel 17 Opening 19 channel outputs 21 grids 23 Sealing 25 first water drainage structure 27 second water drainage structure 29 first cover 31 second cover 33 Passive membrane

Claims

[1] Sound generating device (1) for applications in an AVAS vehicle, comprising a two-part housing (3, 5) in which a loudspeaker (11) for outputting an acoustic signal and a signal frequency extension unit are positioned, wherein the loudspeaker (11) is arranged in a first housing part (3) whose protective grille in front of the loudspeaker diaphragm (13) is in direct contact with the environment of the vehicle, and the first housing part (3) is covered with a second housing part (5), characterized by, that the signal frequency extension unit (15, 33) is positioned on the first housing part (3) next to the loudspeaker (11) arranged in an opening (17) of the first housing part (3) and is covered by the protective grille (21) for direct connection with the environment of the vehicle, and the signal frequency extension unit is designed as a helical or spiral channel (15) wherein the channel (15) has an open channel outlet (19) to the outside of the first housing part (3) and a structure of the helical channel (15) extends in a main shaping direction of the first housing part (3). [2] Sound generating device according to claim 1, characterized by , that the signal frequency extension unit (15) is an integral part of the first housing part (3). [3] Sound generating device according to claim 1 or 2, characterized by, that the open channel outlet (19) is covered with a grid (21), which is preferably an integral part of the first housing part (3). [4] Sound generating device according to at least one of the preceding claims 1 to 3, characterized by , that the spiral or snail-shaped channel (15) is closed at the rear with a seal (23). [5] Sound generating device according to at least one of the preceding claims 1 to 4, characterized by , that the spiral or snail-shaped channel (15) is closed off at the rear by the second housing part (5). [6] Sound generating device according to at least one of the preceding claims 1 to 5, characterized by , that at least one water drainage structure (25, 27) is formed on a front face of the first housing part (3) facing the environment. [7] Sound generating device according to claim 6, characterized by, that at least one water drainage structure (25, 27) is filled with a coarse noise-reducing material. [8] Sound generating device according to claim 1, characterized by , that the signal frequency extension unit is designed as a passive diaphragm (33) which is positioned in the housing which is completely enclosed by the first and second housing parts (3, 5).

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