Coaxial loudspeaker

Abstract

The embodiment of the invention provides a coaxial loudspeaker. The coaxial loudspeaker comprises a shell, a loudspeaker single body accommodated in the shell, and a sound guide channel arranged in the shell, the loudspeaker single body comprises a basin frame, a magnetic circuit system connected with the basin frame, a first vibration system arranged on the inner side of the basin frame, a second vibration system which is arranged on the outer side of the basin frame in a surrounding mode and is coaxial with the first vibration system, and a sealing cover which is arranged on the first vibration system in a covering mode and forms a high-pitch front cavity together with the first vibration system in a surrounding mode. The magnetic circuit system drives the first vibration system to make high pitches and drives the second vibration system to make low pitches, the high pitches and the low pitches are led out of the shell through the sound guiding channel, and the side, away from the first vibration system, of the sealing cover is fixed to the shell in a sealed mode. According to the invention, the sealing of the high-pitch front cavity of the loudspeaker end is realized through the sealing cover, so that the subsequent assembly process of the BOX (sound equipment) end is simplified, the process yield is improved, and in addition, the sealing cover can provide effective support for the loudspeaker monomer.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the technical field of electroacoustic conversion, and particularly relate to a coaxial loudspeaker. Background Art

[0002] A coaxial speaker is one that integrates a tweeter and woofer, with the tweeter and woofer arranged coaxially. The sound sources of a coaxial speaker's tweeter and woofer can be located on the front of the speaker, meaning the two units emit sound in the same direction, or on the front and back of the speaker, meaning the two units emit sound in different directions.

[0003] In the related art, the tweeter front cavity of the tweeter unit of the coaxial speaker is encapsulated through the BOX (sound box) end, which makes the BOX assembly process complicated and affects the yield. In addition, the poor reliability problem caused by encapsulating the tweeter front cavity through the BOX end also needs to be solved urgently.

[0004] Therefore, it is necessary to provide a new coaxial loudspeaker to solve the above technical problems. Summary of the Invention

[0005] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art and provide a coaxial loudspeaker.

[0006] According to one aspect of an embodiment of the present disclosure, a coaxial loudspeaker is provided, comprising: A housing, a speaker unit accommodated in the housing, and a sound guide channel provided in the housing and used to guide the sound emitted by the speaker unit from the interior of the housing to the exterior of the housing; The speaker unit includes a basin, a magnetic circuit system connected to the basin, a first vibration system arranged on the inner side of the basin, a second vibration system arranged around the outer side of the basin and coaxially with the first vibration system, and a cover arranged on the first vibration system and forming a treble front cavity together with the first vibration system. The magnetic circuit system drives the first vibration system to emit treble and drives the second vibration system to emit bass, and the treble and the bass are both guided from the sound guide channel to the outside of the shell, and the side of the cover facing away from the first vibration system is sealed and fixed to the shell.

[0007] Optionally, the cover includes a top wall connected to the inner wall of the shell and a side wall bent and extended from the top wall toward the basin frame, and the cover is connected to the basin frame through the side wall.

[0008] Optionally, the side wall is recessed from the wall surface close to the basin frame toward the top wall to form a sound transmission port, which connects the treble front cavity and the interior of the shell, and is used to guide the treble emitted by the first vibration system to the outside of the shell through the sound guide channel.

[0009] Optionally, a boss abutting and fixed against the top wall is provided on the inner wall of the shell at a position corresponding to the top wall, and the top wall is provided with a through hole penetrating the thickness thereof and exposing the boss.

[0010] Optionally, the through hole includes a first through hole and a second through hole that are spaced apart, and the aperture of the first through hole is larger than the aperture of the second through hole.

[0011] Optionally, the magnetic circuit system is provided with a first magnetic gap and a second magnetic gap located on the outer peripheral side of the first magnetic gap, the first vibration system includes a first diaphragm and a first voice coil connected to the first diaphragm and used to drive the first diaphragm to vibrate and produce sound, the second vibration system includes a second diaphragm and a second voice coil connected to the second diaphragm and used to drive the second diaphragm to vibrate and produce sound, the first voice coil is at least partially inserted in the first magnetic gap, and the second voice coil is at least partially inserted in the second magnetic gap.

[0012] Optionally, the magnetic circuit system includes a magnetic bowl, a central magnetic portion fixed to the magnetic bowl, and a side magnetic portion spaced apart from the central magnetic portion, wherein the second magnetic gap is formed between the central magnetic portion and the side magnetic portion; the central magnetic portion includes a magnetic conductive plate, a first magnetic steel component and a second magnetic steel component located on opposite sides of the magnetic conductive plate along the vibration direction of the first vibration system, wherein the first magnetic steel component is located on the side of the magnetic conductive plate facing the first vibration system and forms the first magnetic gap between the magnetic conductive plate and the magnetic conductive plate.

[0013] Optionally, the magnetic conductive plate includes a bottom arranged between the first magnetic steel assembly and the second magnetic steel assembly and a side portion bent and extended from the bottom toward the first vibration system; the side portion is spaced from the first magnetic steel assembly to form the first magnetic gap.

[0014] Optionally, the speaker unit further includes a perforated shell covering the side of the magnetic circuit system away from the first vibration system, and a receiving space for receiving sound-absorbing material is formed between the perforated shell and the housing.

[0015] Optionally, the cover and the shell are fixed and sealed by glue; or foam is provided between the cover and the shell, and the cover is supported on the shell through the foam seal.

[0016] The beneficial effects of the embodiments of the present disclosure include: In the present invention, the sealing of the tweeter front cavity at the speaker end is achieved through the sealing cover, thereby simplifying the subsequent assembly process of the BOX (audio) end and improving the process yield. In addition, the sealing cover can provide effective support for the speaker unit, improve the reliability of the device, and improve the stability of the high-frequency performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of a coaxial loudspeaker according to an embodiment of the present invention; Figure 2 A schematic structural diagram of a coaxial loudspeaker from another perspective of an embodiment of the present invention; Figure 3 for Figure 2 A cross-sectional view of the coaxial speaker along the AA direction shown in FIG, wherein the positional relationship between the magnetic circuit system, the first vibration system and the second vibration system is schematically shown; Figure 4 for Figure 3 An enlarged schematic diagram of a portion of the coaxial loudspeaker structure shown in area C in the middle; Figure 5 for Figure 3 A partial enlarged schematic diagram of the structure of the coaxial loudspeaker shown in area D in the middle; Figure 6 for Figure 2 A cross-sectional view of the coaxial speaker along the BB direction shown in FIG, wherein the positional relationship between the magnetic circuit system, the first vibration system and the second vibration system is schematically shown; Figure 7 for Figure 6 An enlarged schematic diagram of a portion of the coaxial loudspeaker structure shown in area E in the middle; Figure 8 for Figure 6 A partial enlarged schematic diagram of the structure of the coaxial loudspeaker shown in area F in the middle; Figure 9 for Figure 1 Exploded perspective view of the coaxial loudspeaker shown in ; Figure 10 This is a schematic structural diagram of a cover according to an embodiment of the present invention; Figure 11 is a perspective exploded view of a housing according to an embodiment of the present invention; Figure 12 This is a structural schematic diagram of a basin stand according to an embodiment of the present invention; Figure 13 Schematic diagram of the structure of the second diaphragm in one embodiment of the present invention.

[0018] In the figure, 100, speaker unit; 200, shell; 201, sound guide channel; 202, boss; 1, basin frame; 2, magnetic circuit system; 3, first vibration system; 4, second vibration system; 5, cover; 6, tweeter front cavity; 7, perforated shell; 8, receiving space; 9, insert; 10, support frame; 11, elastic component; 12, first electrical connection member; 13, second electrical connection member; 14, reinforcement member; 17, filling hole; 21, first magnetic gap; 22, second magnetic gap; 23, magnetic conductive plate; 231, receiving hole; 232, side; 233, bottom; 24, central magnetic part; 24 1. First magnetic steel assembly; 242. Pole core; 243. Second magnetic steel assembly; 25. Side magnet portion; 26. Magnetic bowl; 251. Third magnetic steel assembly; 252. Magnetic conductive cover; 31. First diaphragm; 32. First voice coil; 33. Voice coil connector; 41. Second diaphragm; 42. Second voice coil; 43. Voice coil skeleton; 411. Second fold ring; 412. Second dome; 413. Third fold ring; 431. Skeleton flat plate portion; 432. First extension portion; 433. Second extension portion; 51. Top wall; 52. Side wall; 53. Sound transmission port; 511. First through hole; 512. Second through hole. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0020] The following is a further detailed description of the embodiments of the present application in conjunction with the accompanying drawings and examples. The detailed descriptions and drawings of the following examples are used to illustrate the principles of the present application, but are not used to limit the scope of the present application, that is, the present application is not limited to the described embodiments. In the description of the present application, it should be noted that, unless otherwise specified, the meaning of "multiple" is more than two; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not perpendicular in the strict sense, but is within the allowable error range. "Parallel" is not parallel in the strict sense, but is within the allowable error range.

[0021] It should also be noted that, in the description of this application, unless otherwise specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0022] like Figure 1-8 As shown, a coaxial speaker includes: a shell 200, a speaker unit 100 accommodated in the shell 200, and a sound guide channel 201 arranged in the shell 200 and used to guide the sound emitted by the speaker unit 100 from the inside of the shell 200 to the outside of the shell 200.

[0023] The speaker unit 100 includes a basin frame 1, a magnetic circuit system 2 connected to the basin frame 1, a first vibration system 3 arranged on the inner side of the basin frame 1, a second vibration system 4 arranged around the outer side of the basin frame 1 and coaxially with the first vibration system 3, and a cover 5 that covers the first vibration system 3 and together with the first vibration system 3 forms a treble front cavity 6. The magnetic circuit system 2 drives the first vibration system 3 to emit treble and drives the second vibration system 4 to emit bass, and the treble and bass are both guided out of the sound guide channel 201 to the outside of the shell 200. The cover 5 is sealed and fixed to the shell 200 on the side facing away from the first vibration system 3.

[0024] In the present invention, the sealing of the tweeter front cavity 6 at the speaker end is achieved by the cover 5, thereby simplifying the subsequent assembly process of the BOX (audio) end and improving the process yield. In addition, the cover 5 can provide effective support for the speaker unit 100, improve the reliability of the device, and improve the stability of the high-frequency performance of the device.

[0025] refer to Figure 10 In some embodiments, the cover 5 includes a top wall 51 connected to the inner wall of the shell 200 and a side wall 52 bent and extended from the edge of the top wall 51 toward the basin frame 1, and the cover 5 is connected to the basin frame 1 through the side wall 52.

[0026] In some embodiments, the side wall 52 is recessed from the wall surface close to the basin frame 1 toward the top wall 51 to form a sound transmission port 53. The sound transmission port 53 connects the tweeter front cavity 6 and the interior of the shell 200, and is used to guide the treble emitted by the first vibration system 3 to the outside of the shell 200 through the sound guide channel 201.

[0027] In some embodiments, the inner wall of the housing 200 is provided with a boss 202 that is fixedly abutted against the top wall 51, and the top wall 51 is provided with a through hole that penetrates the thickness thereof and exposes the boss 202. Figure 11The housing 200 includes an upper shell 203 and a lower shell 204, and the boss 202 is provided on the surface of the lower shell 204 facing the upper shell 203. A through hole is provided on the top wall 51 that penetrates the thickness thereof and exposes the boss 202, which facilitates automated tooling positioning to improve assembly accuracy.

[0028] Some implementations, continue to refer to Figure 10 The through hole includes a first through hole 511 and a second through hole 512 that are spaced apart. The aperture of the first through hole 511 is larger than the aperture of the second through hole 512. In the present application, by providing two first through holes 511 and second through holes 512 of different sizes, a foolproof effect can be achieved.

[0029] In some embodiments, the magnetic circuit system 2 is provided with a first magnetic gap 21 and a second magnetic gap 22 located on the outer peripheral side of the first magnetic gap 21. The first vibration system 3 includes a first diaphragm 31 and a first voice coil 32 connected to the first diaphragm 31 and used to drive the first diaphragm 31 to vibrate and produce sound. The second vibration system 4 includes a second diaphragm 41 and a second voice coil 42 connected to the second diaphragm 41 and used to drive the second diaphragm 41 to vibrate and produce sound. The first voice coil 32 is at least partially inserted in the first magnetic gap 21, and the second voice coil 42 is at least partially inserted in the second magnetic gap 22.

[0030] refer to Figure 3-4 ,as well as Figure 7-8 In some embodiments, the magnetic circuit system 2 includes a magnetic bowl 26, a central magnetic portion 24 fixed to the magnetic bowl 26, and a side magnetic portion 25 spaced apart from the central magnetic portion 24, with the second magnetic gap 22 formed between the central magnetic portion 24 and the side magnetic portion 25. The central magnetic portion 24 includes a magnetic conductive plate 23, a first magnetic steel assembly 241 and a second magnetic steel assembly 243 located on opposite sides of the magnetic conductive plate 23 along the vibration direction of the first vibration system 3, and the first magnetic steel assembly 241 is located on the side of the magnetic conductive plate 23 facing the first vibration system 3, and the first magnetic gap 21 is formed between the magnetic conductive plate 23 and the magnetic conductive plate 23.

[0031] In some embodiments, the magnetic conductive plate 23 includes a bottom 233 disposed between the first magnetic steel component 241 and the second magnetic steel component 243 and a side portion 232 bent and extended from the bottom 233 toward the first vibration system 3, and the side portion 232 is spaced from the first magnetic steel component 241 to form the first magnetic gap 21.

[0032] Specifically, refer to Figure 5 and Figure 8-9The central magnetic portion 24 includes a first magnetic steel component 241 disposed on the upper surface of the bottom 233 of the magnetic conductive plate 23, and a pole core 242 disposed on the upper surface of the first magnetic steel component 241. A first magnetic gap 21 is formed between the first magnetic steel component 241 and the side portion 232 of the magnetic conductive plate 23. A cut surface 2411 is provided on the outer edge of the surface of the first magnetic steel component 241 near the second vibration system 4. The side magnetic portion 25 includes a third magnetic steel component 251 disposed on the outer periphery of the second magnetic steel component 243 and forming a second magnetic gap 22 with the second magnetic steel component 243, and a magnetic conductive cover plate 252 stacked above the third magnetic steel component 251. The magnetic circuit system 2 also includes a magnetic bowl 26 that supports the second magnetic steel component 243 and the third magnetic steel component 251.

[0033] In some embodiments, a recessed portion 261 is defined at a position of the magnetic bowl 26 corresponding to the second voice coil 42 to provide sufficient vibration space for the second voice coil 42 .

[0034] Furthermore, the first magnetic steel assembly 241, the second magnetic steel assembly 243, and the third magnetic steel assembly 251 are magnetized along the vibration direction of the speaker unit 100, and the first magnetic steel assembly 241 and the second magnetic steel assembly 243 are arranged opposite to each other with the same polarity. That is, the first magnetic steel assembly 241 and the second magnetic steel assembly 243 are magnetized in opposite directions, and the second magnetic steel assembly 243 and the third magnetic steel assembly 251 are magnetized in opposite directions. In this embodiment, the first magnetic steel assembly 241, the pole core 242, the second magnetic steel assembly 243, the third magnetic steel assembly 251, and the magnetic conductive cover plate 252 are all hollow annular structures. In some embodiments, the pole core 242 is sandwiched between the basin frame 1 and the first voice coil 32, and the third magnetic steel assembly 251 is formed by four magnetic steel units axially enclosing the magnetic conductive plate 23.

[0035] refer to Figure 9 and Figure 12 The basin frame 1 is a ring structure with a roughly rectangular outer periphery. The basin frame 1 includes an upper ring wall 15 close to the cover 5 and a lower ring wall 16 arranged above the first magnetic steel assembly 241.

[0036] In a specific embodiment, the width of the upper annular wall 15 is smaller than the width of the lower annular wall 16 in a direction perpendicular to the vibration direction, and the upper and lower annular walls 15 and 16 are flush with each other near the first voice coil 32. The first diaphragm 31 is a concave structure facing downward in the vibration direction and is sleeved on the upper annular wall 15 to achieve a fixed connection between the first diaphragm 31 and the basket frame 1.

[0037] refer to Figure 9 In some embodiments, the first vibration system 3 further includes a voice coil connector 33 sandwiched between the first voice coil 32 and the first diaphragm 31 , and the shape of the voice coil connector 33 is adapted to the shape of the first voice coil 32 .

[0038] In some embodiments, the second diaphragm 41 includes a second fold 411, a second dome 412 disposed around the second fold 411, and a third fold 413 disposed around the second dome 412. The second fold 411 is a structure that protrudes upward along the vibration direction, and the third fold 413 is a structure that is concave downward along the vibration direction. The second diaphragm 41 is used to produce bass sounds, and its sound is emitted in an upward direction along the vibration direction.

[0039] In some embodiments, the second vibration system 4 further includes a voice coil bobbin 43 connecting the second diaphragm 41 and the second voice coil 42 .

[0040] Specifically, refer to Figure 9 and Figure 13 The voice coil bobbin 43 supports the second fold 411 and the second dome 412 and is connected to the second voice coil 42. The end of the second fold 411 close to the first diaphragm 31 is fixed between the lower ring wall 16 of the basin frame 1 and the first magnetic steel assembly 241. The outer edge of the third fold 413 includes a third fixing portion 4131.

[0041] In some embodiments, the speaker unit 100 further includes a perforated shell 7 covering the side of the magnetic circuit system 2 away from the first vibration system 3 , and a receiving space 8 for receiving sound-absorbing material is formed between the perforated shell 7 and the housing 200 .

[0042] In some embodiments, a filling hole 17 is opened on the upper shell 203 , wherein the sound absorbing material is filled into the receiving space 8 through the filling hole 17 .

[0043] In some embodiments, the speaker unit 100 further includes an insert 9, a support frame 10, and an elastic component 11. The insert 9 is disposed within a receiving hole 231 defined by a side portion 232 of the magnetic conductive plate 23. The insert 9 is electrically connected to the first voice coil 32 via a first electrical connector 12. The insert 9 is provided with a first terminal extending therethrough. The first terminal is respectively connected to the first electrical connector 12 and the circuit board, thereby electrically connecting the first voice coil 32 to the circuit board. The insert 9 is also provided with a leakage channel extending therethrough.

[0044] Furthermore, the elastic component 11 is disposed between the second diaphragm 41 and the perforated housing 7 and supports the voice coil bobbin 43 and the support frame 10 respectively and is electrically connected to the second voice coil 42 .

[0045] In some embodiments, the support frame 10 is an annular steel ring, and the third fixing portion 4131 is a concave structure downward along the vibration direction, and is sleeved on the support frame 10 to achieve a fixed connection between the second diaphragm 41 and the support frame 10.

[0046] Specifically, the elastic component 11 includes a circuit board 111 positioned opposite to the third fold ring 413 and a supporting diaphragm 112 connected to the circuit board 111. The second voice coil 42 is electrically connected to the circuit board 111 through a second electrical connector 13. The circuit board 111 is clamped between the support frame 10 and the perforated shell 7.

[0047] In some embodiments, the speaker unit 100 further includes a reinforcement member 14 , which is disposed at an inner ring bending portion of the annular support frame 10 .

[0048] In some embodiments, the number of the elastic components 11 is two and they are disposed in the short axis direction of the speaker unit 100 . In other embodiments, the number may depend on the specific situation.

[0049] The voice coil skeleton 43 is annular and includes a skeleton flat plate portion 431 that is in contact with the second dome 412, a first extension portion 432 that bends and extends from the outer ring edge of the skeleton flat plate portion 431 toward the circuit board 111 and is connected to the circuit board 111, and a second extension portion 433 that bends and extends from the inner ring edge of the skeleton flat plate portion 431 toward the second voice coil 42 and is connected to the second voice coil 42.

[0050] In some embodiments, the cover 5 and the shell 200 are fixed and sealed by glue, or foam is provided between the cover 5 and the shell 200, and the cover 5 is supported on the shell 200 by the foam seal.

[0051] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present disclosure, and the present disclosure is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the present disclosure, and such modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A coaxial loudspeaker, characterized in that: include: A housing, a speaker unit accommodated in the housing, and a sound guide channel provided in the housing and used to guide the sound emitted by the speaker unit from the interior of the housing to the exterior of the housing; The speaker unit includes a basin, a magnetic circuit system connected to the basin, a first vibration system arranged on the inner side of the basin, a second vibration system arranged around the outer side of the basin and coaxially with the first vibration system, and a cover provided on the first vibration system and forming a treble front cavity together with the first vibration system. The magnetic circuit system drives the first vibration system to produce treble and drives the second vibration system to produce bass, and the treble and bass are both guided to the outside of the housing through the sound guide channel. The side of the cover facing away from the first vibration system is sealed and fixed to the housing. The sealing cover includes a top wall connected to the inner wall of the shell and a side wall bent and extended from the top wall toward the basin frame. The sealing cover is connected to the basin frame through the side wall.

2. The coaxial loudspeaker according to claim 1, wherein: The side wall is recessed from the wall surface close to the basin frame toward the top wall to form a sound transmission port, which connects the treble front cavity and the interior of the shell, and is used to guide the treble emitted by the first vibration system to the outside of the shell through the sound guide channel.

3. The coaxial loudspeaker according to claim 1, wherein: A boss abutting and fixed to the top wall is provided at a position of the inner wall of the shell corresponding to the top wall, and the top wall is provided with a through hole penetrating through the thickness thereof and exposing the boss.

4. The coaxial loudspeaker according to claim 3, wherein: The through hole includes a first through hole and a second through hole that are spaced apart from each other. The aperture of the first through hole is larger than that of the second through hole.

5. The coaxial loudspeaker according to claim 1, wherein: The magnetic circuit system is provided with a first magnetic gap and a second magnetic gap located on the outer peripheral side of the first magnetic gap. The first vibration system includes a first diaphragm and a first voice coil connected to the first diaphragm and used to drive the first diaphragm to vibrate and produce sound. The second vibration system includes a second diaphragm and a second voice coil connected to the second diaphragm and used to drive the second diaphragm to vibrate and produce sound. The first voice coil is at least partially inserted in the first magnetic gap, and the second voice coil is at least partially inserted in the second magnetic gap.

6. The coaxial loudspeaker according to claim 5, characterized in that The magnetic circuit system includes a magnetic bowl, a central magnetic part fixed to the magnetic bowl, and a side magnetic part spaced apart from the central magnetic part, wherein the second magnetic gap is formed between the central magnetic part and the side magnetic part; the central magnetic part includes a magnetic conductive plate, a first magnetic steel component and a second magnetic steel component located on opposite sides of the magnetic conductive plate along the vibration direction of the first vibration system, wherein the first magnetic steel component is located on the side of the magnetic conductive plate facing the first vibration system and forms the first magnetic gap between the magnetic conductive plate and the magnetic conductive plate.

7. The coaxial loudspeaker according to claim 6, wherein: The magnetic conductive plate includes a bottom portion disposed between the first magnetic steel component and the second magnetic steel component and a side portion bent and extended from the bottom toward the first vibration system; the side portion is spaced from the first magnetic steel component to form the first magnetic gap.

8. The coaxial loudspeaker according to claim 1, wherein: The speaker unit further includes a perforated shell covering the side of the magnetic circuit system away from the first vibration system, and a receiving space for receiving a sound-absorbing material is formed between the perforated shell and the housing.

9. The coaxial loudspeaker according to claim 1, wherein: The cover and the shell are fixed and sealed by glue; or foam is provided between the cover and the shell, and the cover is supported on the shell by the foam seal.

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