Slender vehicle-mounted bass sound box

Abstract

The utility model discloses a slender vehicle-mounted bass sound box. The sound box comprises a box body, a bass sounding unit and an echo tube, the box body comprises a top plate, side plates and a bottom plate, and a sound cavity enclosed by the top plate, the side plates and the bottom plate is formed in the box body; the top plate is provided with a first mounting hole communicated with the sound cavity, and the top plate or the side plate is provided with a second mounting hole communicated with the sound cavity; the bass sounding unit is mounted in the first mounting hole, the bass sounding unit is provided with a vibrating diaphragm, and the vibrating diaphragm limits a part of the boundary of the sound cavity; the echo tube extends into the sound cavity from the second mounting hole; the minimum distance E between the second mounting hole and the center of the diaphragm satisfies the following formula: Rd < = E < = 3.5 Rd, wherein Rd represents the radius of the diaphragm. According to the slender vehicle-mounted bass sound box, the bass strength, the diving depth and the bass purity and texture of the vehicle-mounted bass sound box are effectively improved on the premise that the volume of the sound box is kept moderate and the cost is controllable.

Description

Technical Field

[0001] This utility model belongs to the field of car audio systems and relates to a slender car subwoofer. Background Technology

[0002] The in-vehicle audio system is a crucial component of the car's smart cockpit, responsible for reproducing sound within the vehicle area (especially the cabin) for entertainment and remote communication. Its performance directly impacts the fidelity of the in-vehicle audio and the overall listening experience. Among these performance metrics, bass response is a key indicator of speaker quality. The in-vehicle subwoofer, as a vital part of the audio system, is responsible for reproducing low-frequency sounds, particularly during music and other entertainment activities, where the quality of low-frequency sound reproduction significantly affects the overall sound quality.

[0003] Existing car subwoofer enclosures often use echo tube structures to improve bass performance. Specifically, a car audio speaker is provided, comprising a housing, a magnetic circuit system fixedly mounted on the housing, and a plug electrically connected to the magnetic circuit system. The housing includes a lower housing and an upper housing fixed above the lower housing by screws. An external echo tube is integrally formed inside the lower housing, with a blind hole at its upper end. An inner echo tube extends downward from the upper housing into the blind hole, and a through hole is provided in the middle of the inner echo tube. While this car audio system uses an echo tube on the housing to enhance the low-frequency performance, traditional car speaker enclosures and their echo tube designs often suffer from insufficient bass power and depth, failing to meet the growing demand for high-quality audio.

[0004] Current car subwoofer designs typically improve bass performance by increasing speaker size, woofer dimensions, or employing complex enclosure structures. However, these methods often result in bulky, expensive enclosures with limited improvement. On the other hand, the echo tube, as a crucial component of the enclosure, directly impacts bass performance. Traditional echo tube designs often fail to fully utilize the internal space, leading to subpar bass. This is especially true for subwoofers with an aspect ratio greater than 1, where space constraints in the car typically limit the size and surface area, resulting in a significant distance between the echo tube and the speaker. In a typical design, the speaker is often located at the front of the enclosure, while the echo tube is positioned at the back. Furthermore, traditional echo tube designs do not account for aerodynamic noise, which can negatively affect the purity and texture of the bass.

[0005] However, the general expectation is that car audio systems should occupy as little space as possible in a car, be cost-effective, and still deliver good low-frequency performance. Existing car subwoofers take up a significant amount of space, especially in the horizontal dimension, and their low-frequency reproduction quality needs further improvement.

[0006] The information disclosed in the background section is only intended to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0007] In view of this, the present invention provides a novel, slender car subwoofer that effectively improves the bass power, depth, purity, and texture of the bass while maintaining a moderate size and controllable cost. It is a product with excellent bass performance.

[0008] The present invention adopts the following technical solution:

[0009] A slender vehicle-mounted subwoofer enclosure includes a cabinet, a subwoofer unit, and a sound tube. The cabinet includes a top plate, a side plate, and a bottom plate. A sound cavity is formed inside the cabinet, which is enclosed by the top plate, the side plate, and the bottom plate.

[0010] The distance between the top plate and the bottom plate is defined as the length L of the box body, and the width or diameter of the top plate is defined as the width W of the box body, where 1 < L / W ≤ 10; the area of ​​the bottom plate is smaller than the area of ​​the top plate, and one of the side plates includes an inclined plate or a stepped plate; the width of the box body gradually decreases from the top to the bottom.

[0011] The top plate is provided with a first mounting hole communicating with the sound cavity, and the top plate or the side plate is provided with a second mounting hole communicating with the sound cavity;

[0012] The bass unit is mounted in the first mounting hole, and the bass unit has a diaphragm that defines a portion of the boundary of the acoustic cavity;

[0013] The echo tube extends from the second mounting hole into the sound cavity;

[0014] The minimum distance E between the second mounting hole and the center of the diaphragm satisfies the following formula: Rd≤E≤3.5Rd, where Rd represents the radius of the diaphragm.

[0015] In a preferred embodiment, the echo tube has an outer end portion connected to the second mounting hole and an inner end portion farther from the second mounting hole, the inner end portion including a chamfered structure whose outer diameter gradually increases from the inside to the outside.

[0016] In a more preferred embodiment, in a first cross-section along the centerline of the echo tube, the profile of the chamfered structure includes an arc segment, the radius Rts of which satisfies the following formula: Rts≥0.25Dts, where Dts represents the diameter or width of the echo tube.

[0017] In a further preferred embodiment, 0.25Dts≤Rts≤Dts.

[0018] In a further preferred embodiment, the second cross-section of the echo tube perpendicular to its centerline is a circle or a polygon, where Dts is the diameter of the circle or polygon, and the diameter of the polygon is the maximum distance between any two points on the polygon.

[0019] In a more preferred embodiment, the portion of the echo tube located above the chamfered structure is a circular tube with a uniform diameter.

[0020] In a preferred embodiment, the second mounting hole is formed on the top plate, and the echo tube extends downward from the top plate to its inner end at half the height of the enclosure.

[0021] In a more preferred embodiment, the echo tube is located on the side with the greater depth of the acoustic cavity.

[0022] In a more preferred embodiment, the upper end face of the echo tube is attached to the lower surface of the top plate, and the inner surface of the echo tube and the wall of the second mounting hole form a continuous surface.

[0023] In a preferred embodiment, the bass-generating unit is a dynamic loudspeaker, the diaphragm has an effective radiating portion capable of elastic deformation and a suspension edge surrounding the effective radiating portion, Rd represents the radius of the effective radiating portion, the suspension edge is connected to the top plate or a bracket on the top plate, the magnetic circuit system of the dynamic loudspeaker is located inside the diaphragm and the two form the inner cavity of the loudspeaker, the inner cavity and the acoustic cavity are interconnected.

[0024] The present invention adopts the above solution and has the following advantages:

[0025] This utility model features a slender car subwoofer enclosure that optimizes the relative positions of the echo tube and the bass driver unit, significantly improving the depth and power of the low-frequency response and enhancing the listening experience. Addressing the limitations of vehicle space, the enclosure maintains excellent sound quality while effectively controlling its size, facilitating placement within the vehicle. The inclined or stepped design of the side panels aids in the subwoofer's placement within the car, providing space to accommodate other components and ensuring a good match with the vehicle's layout.

[0026] In the preferred design, the chamfered structure of the echo tube effectively reduces the noise generated when airflow passes through the echo tube, which not only improves the purity of the sound quality, but also makes the sound reproduction clearer and less interference-free, resulting in a better listening experience when playing music. Attached Figure Description

[0027] To more clearly illustrate the technical solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a perspective view of a vehicle-mounted subwoofer according to an embodiment of the present utility model.

[0029] Figure 2 This is a perspective view of a vehicle-mounted subwoofer according to an embodiment of the present utility model.

[0030] Figure 3 This is a schematic diagram of a vehicle-mounted subwoofer according to Embodiment 1 of the present invention.

[0031] Figure 4 This is a schematic diagram of a vehicle-mounted subwoofer according to Embodiment 2 of this utility model.

[0032] Figure 5 This is a schematic diagram of a car subwoofer for comparison.

[0033] Figure 6 The frequency response curves are for three types of car subwoofers: Example 1, Example 2, and Comparative Example.

[0034] Figure 7 This is a schematic diagram of a vehicle-mounted subwoofer according to Embodiment 3 of the present invention.

[0035] Figure 8 The frequency response curves of the vehicle-mounted subwoofer with three chamfer radii according to Embodiment 3 of this utility model are shown.

[0036] In the above attached figures,

[0037] 1. Enclosure; 10. Acoustic cavity; 11. Top plate; 12. Side plate; 121. First side plate; 122. Second side plate; 123. Third side plate; 13. Bottom plate; 14. First mounting hole; 15. Second mounting hole;

[0038] 2. Bass driver unit; 21. Diaphragm; 211. Effective radiator; 212. Suspension edge;

[0039] 3. Echo tube; 31. Chamfered structure; 311. Circular arc segment. Detailed Implementation

[0040] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted that the description of these embodiments is for the purpose of aiding understanding the present invention, but does not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0041] In this article, "inner" and "outer" are defined with reference to the geometric center of the enclosure. The direction closer to the geometric center of the enclosure is considered inner, and vice versa. The directional terms "top" and "bottom" are intended to help those skilled in the art understand the structure of the car subwoofer enclosure and are not used to limit the state of the car subwoofer enclosure after it is installed in the vehicle.

[0042] Furthermore, in this article, the term "bass" refers to sound with a frequency range of 20 to 200 Hz; "bass unit" refers to a sound reproduction device that reproduces sound concentrated in the frequency range of 20 to 200 Hz; correspondingly, "bass speaker" refers to a loudspeaker used to reproduce sound in the frequency range of 20 to 200 Hz.

[0043] The design of a car subwoofer enclosure plays a crucial role in sound quality. This is especially true for elongated car subwoofers (subwoofers) with an aspect ratio greater than 1, whose unique shape necessitates careful consideration of volume and surface area limitations during design. These limitations not only affect the enclosure's appearance but also pose challenges to its internal acoustic structure. Based on practical experience and research, the inventors have discovered that the design of elongated car subwoofer enclosures requires comprehensive consideration of the following three aspects.

[0044] 1. Insufficient Bass Response: Due to space limitations in car interiors, traditional speaker enclosures typically have a considerable distance between the sound tube and the speaker. This layout is primarily for space utilization and aesthetic reasons. However, the inventors discovered that the distance between the speaker and the sound tube significantly impacts the speaker's bass performance. When the speaker is far from the sound tube, bass waves may encounter more obstacles and attenuation during propagation, resulting in insufficient bass power and depth. This is mainly because bass wavelengths are relatively long and are more susceptible to the influence of the enclosure's internal structure and surface materials during propagation. A lack of or insufficient bass reduces the overall listening experience, causing music to lose its layering and three-dimensionality.

[0045] 2. Aerodynamic noise issue: The chamfered design of the echo tube has a significant impact on airflow. If the chamfer design is not optimized, the airflow passing through the echo tube may generate considerable aerodynamic noise. This noise can interfere with the purity of the music and reduce sound quality.

[0046] 3. The conflict between size and space: To achieve optimal bass response, speaker enclosures often require a large size. However, within the limited space of a car, a large speaker enclosure can take up too much space, affecting passenger comfort and the vehicle's practicality. Maintaining sound quality without increasing speaker size has always been a challenge.

[0047] 4. Balancing Cost and Performance: In pursuit of superior sound quality, some high-end speakers employ expensive materials and complex designs and processes. However, this also leads to higher prices, limiting their widespread adoption in the mass market. Finding a balance between cost and performance to provide products with better value for money is a pressing issue that needs to be addressed.

[0048] Based on the above research, a novel, slender car subwoofer enclosure is provided. For example... Figure 1 and Figure 2 As shown, the slender car subwoofer enclosure includes a housing 1, a subwoofer unit 2, and a reverberation tube 3.

[0049] The enclosure 1 includes a top plate 11, side plates 12, and a bottom plate 13. A sound cavity 10, enclosed by the top plate 11, side plates 12, and bottom plate 13, is formed within the enclosure 1. The distance between the top plate 11 and the bottom plate 13 is defined as the length L of the enclosure 1, and the width or diameter of the top plate 11 is defined as the width W of the enclosure 1, where L / W > 1; that is, this vehicle-mounted subwoofer enclosure is a long and narrow enclosure. It should also be noted that, due to space constraints in the vehicle, the shape of the enclosure 1 is often irregular. The attached diagram is a simplified schematic of the subwoofer vehicle audio system; some structural details (such as the assembly structure with the vehicle) are not shown. The length L of the enclosure 1 refers to the maximum distance between the top plates 11. In a typical embodiment, the top plate 11 and the bottom plate 13 are arranged substantially parallel, and the side plate 12 connects between the top plate 11 and the bottom plate 13, enclosing and forming the enclosure. The length L of the enclosure 1 is equal to the distance between the top plate 11 and the bottom plate 13. If the top plate 11 is circular, then the width W of the box 1 refers to the diameter of the top plate 11; if the top plate 11 is an irregular shape or a polygon, then the width W of the box 1 is equal to the diameter of the irregular shape or polygon, where the diameter of the irregular shape or polygon refers to the maximum distance between any two points on the polygon. In one embodiment, 1 < L / W ≤ 10.

[0050] The top width of the enclosure 1 is greater than the bottom width. Further, the width of the enclosure 1 gradually decreases from top to bottom. In a typical embodiment, the area of ​​the bottom plate 13 is smaller than the area of ​​the top plate 11. The side plates 12 include a first side plate 121, a second side plate 122, and two third side plates 123. The first side plate 121 defines the front boundary of the acoustic cavity 10, the second side plate 122 defines the rear boundary of the acoustic cavity 10, and the two third side plates 123 define the left and right boundaries of the acoustic cavity 10, respectively. The upper and lower boundaries of the acoustic cavity 10 are defined by the top plate 11 and the bottom plate 13, respectively. The enclosure 1 has a first mounting hole 14 and a second mounting hole 15. The first mounting hole 14 is equipped with a bass resonator 2 and is enclosed by the bass resonator 2; the second mounting hole 15 is used to install a sound tube 3, thus communicating with the outside. Therefore, except for the second mounting hole 15 which communicates with the outside atmosphere, the other boundaries of the acoustic cavity 10 of the enclosure 1 are closed boundaries, enclosed by the enclosure 1 or the bass resonator 2. (See attached...) Figure 1 and Figure 2 In the specific example shown, the first side panel 121, the second side panel 122 and the third side panel 123 on the left are regular vertical panels; the third side panel 123 on the right includes an inclined panel or a stepped panel, thus the width of the box 1 gradually decreases from top to bottom or decreases in a stepped manner.

[0051] The bass driver unit 2 is mounted in the first mounting hole 14. The bass driver unit 2 has a diaphragm 21 that covers the first mounting hole 14; that is, the diaphragm 21 also defines a portion of the boundary of the acoustic cavity 10. For ease of showing the position of the diaphragm 21, the internal structure of the bass driver unit 2 (voice coil, positioning support, and magnetic circuit system, etc.) is not shown. In a typical embodiment, the bass driver unit 2 is a moving-coil loudspeaker. Figure 2 As shown, the diaphragm 21 has an effective radiating portion 211 capable of elastic deformation and a suspension edge 212 surrounding the effective radiating portion 211, where Rd represents the radius of the effective radiating portion 211. The suspension edge 212 is connected to the top plate 11 or a bracket on the top plate 11. The magnetic circuit system of the moving coil loudspeaker is located inside the diaphragm 21, and the two form the loudspeaker's inner cavity, which is interconnected with the acoustic cavity 10. That is, when the first loudspeaker is working, the vibration of the diaphragm 21 causes the air inside the acoustic cavity 10 to vibrate, forming an airflow that enhances the bass response. In a specific example of the diaphragm 21, the diaphragm 21 includes a cone, and the aforementioned effective radiating portion 211 includes this cone; that is, the part of the diaphragm 21 that participates in vibration is its effective radiating portion 211; components that do not participate in vibration, such as the suspension edge 212, are not included in the effective radiating portion 211. In addition, the voice coil, magnetic circuit system and other components of the woofer are located inside the enclosure 1, that is, outside the diaphragm 21; in other embodiments, the voice coil, magnetic circuit system and other components may also be located outside the enclosure 1.

[0052] The echo tube 3 is a hollow tubular component with open ends, used to guide and realize the gas flow between the sound cavity 10 and the external atmosphere. In this embodiment, the echo tube 3 is located in the sound cavity 10. The echo tube 3 also has an outer end that connects to the second mounting hole 15 and an inner end that is farther away from the second mounting hole 15. The outer end of the echo tube 3 extends from the second mounting hole 15 into the sound cavity 10.

[0053] The minimum distance E between the center of the second mounting hole 15 and the diaphragm 21 satisfies the following formula: Rd≤E≤3.5Rd, where Rd represents the radius of the diaphragm 21. Figure 7 As shown, the inner end of the echo tube 3 includes a chamfered structure 31 with an outer diameter that gradually increases from the inside to the outside, used to guide airflow. In a first cross-section along the centerline of the echo tube 3, the profile of the chamfered structure 31 includes an arc segment 311, the radius Rts of which (in some embodiments, Rts refers to the chamfer radius) satisfies the following formula: Rts ≥ 0.25Dts, where Dts represents the diameter or width of the echo tube 3. Further, 0.25Dts ≤ Rts ≤ Dts. The second cross-section of the echo tube 3 perpendicular to its centerline is circular or polygonal, and Dts is the diameter of the circular or polygonal shape.

[0054] The specific embodiments shown in the accompanying drawings will be described in detail below.

[0055] Example 1

[0056] like Figure 3 As shown, both the first mounting hole 14 and the second mounting hole 15 are located on the top plate 11 of the enclosure 1. The first mounting hole 14 is located in the center of the top plate 11, and the second mounting hole 15 is located above the deeper part of the enclosure 1. The echo tube 3 is located on the left side of the sound cavity 10 (at greater depth), its upper end face is in contact with the lower surface of the top plate 11, and its inner surface forms a continuous surface with the wall of the second mounting hole 15; the inner end of the echo section extends downward to half the height of the enclosure 1; the echo tube 3 is a circular tube with a uniform diameter. The minimum distance E between the center O of the diaphragm 21 and the second mounting hole 15 is 125 mm.

[0057] Example 2

[0058] like Figure 4As shown, the first mounting hole 14 is formed on the top plate 11 of the enclosure 1, and the second mounting hole 15 is formed on the side plate 12 of the enclosure 1, specifically on the first side plate 121. The first mounting hole 14 is located in the center of the top plate 11, and the second mounting hole 15 is approximately located at half the height of the first side plate 121. The front end face of the echo tube 3 is in contact with the inner surface of the first side plate 121, and its inner surface and the hole wall of the second mounting hole 15 form a continuous surface; the inner end of the echo section extends rearward and is a distance away from the second side plate 122. That is, there is a gap between the inner end of the echo tube 3 and the enclosure 1 to allow airflow to enter and exit. The minimum distance E between the center O of the diaphragm 21 and the second mounting hole 15 is 185 mm.

[0059] Comparative Example

[0060] like Figure 5 As shown, the first mounting hole 14 is formed on the top plate 11 of the enclosure 1, and the second mounting hole 15 is formed on the bottom plate 13 of the enclosure 1. The first mounting hole 14 is located in the center of the top plate 11, and the second mounting hole 15 is located in the lower part of the deeper part of the enclosure 1. The echo tube 3 is located on the left side of the sound cavity 10 (at greater depth), and its lower end face is in contact with the upper surface of the bottom plate 13. Its inner surface and the hole wall of the second mounting hole 15 form a continuous surface; the inner end of the echo section extends upward to half the height of the enclosure 1. The minimum distance E between the center O of the diaphragm 21 and the second mounting hole 15 is 402 mm.

[0061] Comparison of sound production performance:

[0062] The sound performance of the three vehicle-mounted subwoofers from Example 1, Example 2, and the comparative example was tested under the same conditions. Their respective frequency response curves are referenced. Figure 6 As shown, within the 100Hz frequency band, the sound pressure level of Example 1 is better than that of Example 2, and the sound pressure level of Example 2 is better than that of the comparative example. In particular, within the 50Hz frequency band, the difference between the sound pressure level of Example 1, Example 2 and the comparative example is more than 1dB.

[0063] Example 3

[0064] This embodiment is in Figure 1 Based on the speaker shown, the structure of the echo tube 3 is further optimized. For example... Figure 7 As shown, the inner end of the echo tube 3 includes a chamfered structure 31 with an outer diameter that gradually increases from the inside to the outside, used to guide airflow. In the first cross-section along the centerline of the echo tube 3, the outline of the chamfered structure 31 includes an arc segment 311, the radius Rts of which satisfies the following formula: Rts ≥ 0.25Dts. The main body of the echo tube 3 above the chamfered structure 31 is a uniformly shaped circular tube. The influence of the radius Rts on the sound production performance is as follows:

[0065] The sound performance of the three specific speaker structures according to Example 3 was tested under the same conditions. Their respective frequency response curves are referenced. Figure 8 As shown, within the frequency range of 40–100 Hz, the sound pressure level of the speaker with Rts = 0.35 Dts is better than that of the speaker with Rts = 0.25 Dts, and the sound pressure level of the speaker with Rts = 0.25 Dts is better than that of the speaker with Rts = 0.2 Dts.

[0066] In general, the main problems with in-vehicle audio equipment technology include insufficient bass response, aerodynamic noise interference, the conflict between size and space, and the imbalance between cost and performance. These problems affect the sound quality, practicality, and market competitiveness of audio equipment to varying degrees. Specifically, the relatively large distance between the echo tube 3 and the speaker, as well as the suboptimal chamfering design of the echo tube 3, results in a slow and weakened bass response, accompanied by aerodynamic noise, all of which directly reduce the listening experience. Furthermore, to meet sound quality requirements, traditional speaker enclosures often require a large size, creating placement difficulties in the limited space of a car interior. At the same time, the high cost of high-end speaker enclosures also limits their widespread adoption in the mass market.

[0067] The solution provided in this embodiment addresses and optimizes the aforementioned issues. By adjusting the relative position of the echo tube 3 and the speaker, and optimizing the chamfer design of the echo tube 3, the speed and power of the bass response can be significantly improved, and the interference of aerodynamic noise can be reduced, thereby enhancing the overall sound quality. Furthermore, this embodiment, while maintaining sound quality, resolves the conflict between volume and space through innovative structural design, eliminating the need to increase the volume of the speaker enclosure 1. Simultaneously, through reasonable material selection and process optimization, this embodiment aims to find a better balance between cost and performance, providing a more cost-effective product.

[0068] In summary, the solution provided in this embodiment solves problems such as insufficient bass response, aerodynamic noise interference, contradiction between size and space, and imbalance between cost and performance, thereby improving the sound quality, practicality, and market competitiveness of in-vehicle audio equipment.

[0069] As indicated in this specification and claims, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, and these steps and elements do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0070] It can be further understood that in this disclosure, "multiple" refers to two or more, and other quantifiers are similar.

[0071] It is further understood that the terms "first," "second," etc., are used to describe various types of information, but this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another, and do not indicate a specific order or degree of importance. In fact, the expressions "first," "second," etc., are completely interchangeable. For example, without departing from the scope of this disclosure, first information can also be referred to as second information, and similarly, second information can also be referred to as first information.

[0072] The above embodiments are only for illustrating the technical concept and features of this utility model, and are preferred embodiments. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly, and they cannot be used to limit the protection scope of this utility model.

Claims

1. A slim, elongated vehicle-mounted subwoofer enclosure, comprising a housing, a subwoofer driver, and a reverberation tube, characterized in that, The enclosure includes a top plate, side plates, and a bottom plate, and a sound cavity is formed inside the enclosure by the top plate, the side plates, and the bottom plate; The distance between the top plate and the bottom plate is defined as the length L of the box body, and the width or diameter of the top plate is defined as the width W of the box body, where 1 < L / W ≤ 10; the area of ​​the bottom plate is smaller than the area of ​​the top plate, and one of the side plates includes an inclined plate or a stepped plate; the width of the box body gradually decreases from the top to the bottom. The top plate is provided with a first mounting hole communicating with the sound cavity, and the top plate or the side plate is provided with a second mounting hole communicating with the sound cavity; The bass unit is mounted in the first mounting hole, and the bass unit has a diaphragm that defines a portion of the boundary of the acoustic cavity; The echo tube extends from the second mounting hole into the sound cavity; The minimum distance E between the second mounting hole and the center of the diaphragm satisfies the following formula: Rd≤E≤3.5Rd, where Rd represents the radius of the diaphragm.

2. The elongated vehicle-mounted subwoofer according to claim 1, characterized in that, The echo tube has an outer end that connects to the second mounting hole and an inner end that is farther away from the second mounting hole. The inner end includes a chamfered structure whose outer diameter gradually increases from the inside to the outside.

3. The elongated vehicle-mounted subwoofer according to claim 2, characterized in that, In the first cross-section along the centerline of the echo tube, the profile of the chamfered structure includes an arc segment, the radius Rts of which satisfies the following formula: Rts≥0.25Dts, where Dts represents the diameter or width of the echo tube.

4. The elongated vehicle-mounted subwoofer according to claim 3, characterized in that, 0.25Dts≤Rts≤Dts.

5. The elongated vehicle-mounted subwoofer according to claim 3, characterized in that, The second cross-section of the echo tube perpendicular to its center line is a circle or a polygon, and Dts is the diameter of the circle or polygon. The diameter of the polygon refers to the maximum distance between any two points on the polygon.

6. The elongated vehicle-mounted subwoofer according to claim 2, characterized in that, The portion of the echo tube located above the chamfered structure is a circular tube with a uniform diameter.

7. The elongated vehicle-mounted subwoofer according to claim 1, characterized in that, The second mounting hole is formed on the top plate, and the echo tube extends downward from the top plate to its inner end, reaching half the height of the enclosure.

8. The elongated vehicle-mounted subwoofer according to claim 1, characterized in that, The echo tube is located on the side with greater depth of the sound cavity.

9. The elongated vehicle-mounted subwoofer according to claim 1, characterized in that, The upper end face of the echo tube is attached to the lower surface of the top plate, and the inner surface of the echo tube and the wall of the second mounting hole form a continuous surface.

10. The elongated vehicle-mounted subwoofer according to claim 1, characterized in that, The bass driver is a dynamic loudspeaker. The diaphragm has an effective radiating part that can elastically deform and a suspension edge surrounding the effective radiating part. Rd represents the radius of the effective radiating part. The suspension edge is connected to the top plate or a bracket on the top plate. The magnetic circuit system of the dynamic loudspeaker is located inside the diaphragm, and the two form the inner cavity of the loudspeaker. The inner cavity and the acoustic cavity are interconnected.

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