A vehicle-mounted bass speaker device and design method thereof

Abstract

The present invention discloses a vehicle-mounted woofer speaker device and a design method thereof. The vehicle-mounted woofer speaker device includes a box and a woofer speaker disposed in the box, the woofer speaker includes a paper cone, the paper cone has a front surface facing the interior of the vehicle and a rear surface opposite thereto, a cavity is formed between the rear surface of the paper cone and the box, a main waveguide for connecting the cavity to the outside is provided in the box, and a secondary waveguide is also provided in the box, the main waveguide and the secondary waveguide each have an inlet connected to the cavity, the main waveguide has an outlet for connecting to the outside of the vehicle, and the secondary waveguide has an outlet for connecting to the outside or inside of the vehicle. The woofer speaker device of the present invention has high sensitivity, more obvious low-frequency extension, and improved sound pressure level at low frequencies; the design method of the present invention can adjust and control more parameters and has a large degree of freedom.

Description

Technical Field

[0001] The present invention relates to the field of vehicle-mounted loudspeakers, and in particular to a vehicle-mounted bass loudspeaker device. Background Art

[0002] For high-quality car audio systems, woofers are crucial. Currently, ventilated speakers are a type of woofer unit that directs the forward or rearward sound waves radiated by the speaker into the vehicle cabin via a waveguide. This system primarily uses a tube to direct the rearward radiated energy into the vehicle cabin. The tube and the speaker's rear cavity act as a Helmholtz resonator. Adjusting the size of the rear cavity and the length and thickness of the tube can adjust the woofer's low-frequency resonance frequency and high-frequency cutoff frequency. Summary of the Invention

[0003] The object of the present invention is to provide a vehicle-mounted bass speaker device, which has high sensitivity, more obvious low-frequency extension, and improved sound pressure level at low frequencies.

[0004] The present invention also provides a design method for a vehicle-mounted bass speaker device, which can adjust and control more parameters and has a greater degree of freedom.

[0005] To achieve the above-mentioned objectives, the present invention provides, on one hand, a vehicle-mounted woofer device, comprising a box and a woofer disposed in the box, the woofer comprising a paper cone having a front surface facing the interior of a vehicle compartment and a rear surface opposite thereto, a cavity being formed between the rear surface of the paper cone and the box, a main waveguide for connecting the cavity to the outside being provided in the box, and a secondary waveguide being further provided in the box, the main waveguide and the secondary waveguide respectively having an inlet communicating with the cavity, the main waveguide having an outlet for connecting to the outside of the vehicle compartment, and the secondary waveguide having an outlet for connecting to the outside or inside of the vehicle compartment.

[0006] Preferably, the paper basin is fixedly arranged on the basin stand, the front end of the box body is open, the basin stand is fixedly connected to the front end of the box body, the rear end of the box body is provided with a rear cover, and each of the outlets is respectively provided on the rear cover.

[0007] More preferably, a first partition is provided in the box, the first partition is located between the woofer and the back cover to form the cavity on the front side of the first partition, the main waveguide and the auxiliary waveguide are formed between the first partition and the back cover, and each of the inlets is respectively provided on the first partition.

[0008] Furthermore, a second partition, a third partition and a fourth partition are also provided in the box body. The second partition divides the space between the first partition and the back cover into a first space part and a second space part. The third partition divides the first space part to form the main waveguide tube. The fourth partition divides the second space part to form the sub-waveguide tube.

[0009] Furthermore, the third partition plate and the fourth partition plate are both arc-shaped, the two arcs have a common center, and the radius of the third partition plate is smaller than the radius of the fourth partition plate.

[0010] Furthermore, the head end of the third partition plate and the head end of the fourth partition plate are respectively connected to the second partition plate, and a gap connecting the corresponding waveguide tube outlets is formed between the tail ends of the third partition plate, the fourth partition plate and the second partition plate, wherein the head end of the fourth partition plate is adjacent to the tail end of the third partition plate.

[0011] Preferably, the cross-sectional areas of the main waveguide tube and the auxiliary waveguide tube perpendicular to the airflow direction first decrease and then increase.

[0012] Preferably, the magnetic circuit system of the woofer is installed on the front side of the paper cone, the rear end of the voice coil of the woofer is connected to the paper cone, and the front end of the voice coil is inserted into the magnetic gap formed by the magnetic circuit system.

[0013] More preferably, the magnetic circuit system is mounted on the basin frame via a bracket, and the bracket is provided with a through hole for airflow to pass through.

[0014] More preferably, the woofer further comprises a centering support plate, wherein the centering support plate is fixedly arranged at the rear end portion of the voice coil, the centering support plate is located at the rear side of the paper cone, and the outer periphery of the centering support plate is mounted on the cone frame through a bracket, and the bracket is provided with a through hole for airflow to pass through.

[0015] Another aspect of the present invention provides a method for designing the vehicle-mounted woofer speaker device as described above, the method comprising the following steps:

[0016] S1. Select a main waveguide and a secondary waveguide, and calculate the total radiation impedance of the selected main waveguide and the secondary waveguide;

[0017] S2. Construct a model of the loudspeaker device according to the radiation impedances of the main waveguide and the auxiliary waveguide obtained in step S1. The model is represented by the following differential equations:

[0018]

[0019] Among them, U(t) is the voltage output by the front-end amplifier of the speaker unit, R eis the DC resistance of the voice coil, i(t) is the current in the voice coil, L e is the inductance of the voice coil, Bl is the electromagnetic induction coefficient, v(t) is the movement speed of the voice coil, M ms is the vibration mass of the loudspeaker vibration system, R ms is the vibration resistance of the loudspeaker vibration system, K ms is the stiffness coefficient of the loudspeaker vibration system, is the relationship between the vibration acceleration of the loudspeaker vibration system and time. is the relationship between the vibration velocity of the loudspeaker vibration system and time, X(t) is the relationship between the vibration displacement of the loudspeaker vibration system and time, and t is time;

[0020] S3, calculating the radiated sound field of the speaker device according to the model established in step S2;

[0021] S4. Compare the radiated sound field obtained in step S3 with the expected radiated sound field. If the expected radiated sound field is met, it is determined that the main waveguide and the auxiliary waveguide meet the design requirements; if the expected radiated sound field is not met, adjust the structures of the main waveguide and the auxiliary waveguide.

[0022] In one embodiment, step S1 specifically includes step S11 of calculating the radiation impedance of the main waveguide, step S12 of calculating the radiation impedance of the auxiliary waveguide, and step S13 of calculating the total radiation impedance of the main waveguide and the auxiliary waveguide.

[0023] Step S11 specifically includes:

[0024] S111. Calculate the radiation impedance Z of the main waveguide end opening ar , the cross-sectional area of ​​the end of the main waveguide is S aL , radius a, opening radiation impedance Z ar As follows:

[0025] Z ar =R ar +jωM ar

[0026] Among them, the acoustic radiation resistance R ar1 As shown below,

[0027]

[0028] Acoustic radiation resistance ar As shown below,

[0029]

[0030] And, j is the imaginary unit, ω is the angular frequency, ρ0 is the density of the medium in which the sound wave propagates, c0 is the speed of the sound wave propagating in the air, and k is the wave number, which is specifically defined as k = ω / c0;

[0031] S112. Calculate the distributed impedance of the main waveguide. Divide the waveguide into n sections according to the curvature of the main waveguide. Each section is a cylinder with a cross-sectional area of ​​S. i , length is Δl i The radiation inductance of the i-th waveguide ΔL i and radiation resistance ΔC i As shown below:

[0032]

[0033] Among them, 1≤i≤n;

[0034] S113. Obtain the total radiation impedance of the main waveguide by step calculation.

[0035] Calculate the total impedance Z of the n-th section tube and the opening radiation n1 ,

[0036]

[0037] Calculate the n-1 section of the cross section tube and Z n The total impedance Z between n-1 ,

[0038]

[0039] Similarly, the total radiation impedance Z to the main waveguide and the radiation opening is a0 for

[0040]

[0041] Step S12 specifically includes:

[0042] S121. Calculate the radiation impedance Z of the secondary waveguide end opening br The cross-sectional area of ​​the auxiliary waveguide end is S bL , radius b, opening radiation impedance Z br As follows:

[0043] Z br =R br +jωM br

[0044] Among them, the acoustic radiation resistance R br1 As shown below,

[0045]

[0046] Acoustic radiation resistance ar As shown below,

[0047]

[0048] And, j is the imaginary unit, ω is the angular frequency, ρ0 is the density of the medium in which the sound wave propagates, c0 is the speed of the sound wave propagating in the air, and k is the wave number, which is specifically defined as k = ωc0;

[0049] S122. Calculate the distributed impedance of the auxiliary waveguide. Divide the waveguide into n sections according to the curvature of the auxiliary waveguide. Each section is a cylinder with a cross-sectional area of ​​S. i , length is Δl i The radiation inductance of the i-th waveguide ΔL i and radiation resistance ΔC i As shown below:

[0050]

[0051] Among them, 1≤i≤n;

[0052] S123. Obtain the total radiation impedance of the auxiliary waveguide by step calculation.

[0053] Calculate the total impedance Z of the n-th section tube and the opening radiation n1 ,

[0054]

[0055] Calculate the n-1 section of the cross section tube and Z n The total impedance Z between n-1 ,

[0056]

[0057] Similarly, the total radiation impedance Z to the auxiliary waveguide and the radiation opening is b0 for

[0058]

[0059] At the same time, we can calculate the radiation impedance Z of the opening at the connection between the main waveguide and the auxiliary waveguide i and cross-sectional area S i .

[0060] In step S13, the radiation impedance Z1 of the waveguide is:

[0061] Z1=R0+jωM0

[0062] When the main waveguide needs to be used, the radiation impedance Z1 of the waveguide is:

[0063] Z1=Za0 =R a0 +jωM a0

[0064] When a secondary waveguide is required, the radiation impedance Z1 of the waveguide is:

[0065] Z1=Z b0 =R b0 +jωM b0

[0066] When both the main and auxiliary waveguides are used, the radiation impedance Z1 of the waveguide is:

[0067] Z1=Z a0 +Z b0 =R b0 +jωM b0 +R a0 +jωM a0

[0068] R a0 is the main waveguide radiation resistance, M a0 is the main waveguide radiation quality, R b0 is the radiation resistance of the secondary waveguide, M b0 is the radiation quality of the secondary waveguide.

[0069] In one embodiment, the mathematical model of the loudspeaker device in step S2 is used to describe the loudspeaker device and the primary and secondary waveguides.

[0070] In one embodiment, step S2 specifically includes:

[0071] S21. The loop equation of the speaker system circuit is as follows:

[0072]

[0073] Among them, U(t) is the voltage output by the front-end amplifier of the speaker unit, R e is the DC resistance of the voice coil, i(t) is the current in the voice coil, L e is the inductance of the voice coil, Bl is the electromagnetic induction coefficient, v(t) is the speed of the voice coil, and t is time;

[0074] S22. The vibration loop equation of the loudspeaker system is as follows:

[0075]

[0076] Among them, M m is the mass of the diaphragm and voice coil, R m is the vibration impedance, K mis the elastic force coefficient of the elastic components such as the positioning support, and X(t) is the relationship between the vibration displacement of the loudspeaker vibration system and time;

[0077] S23. The influence of the radiation impedance of the primary and secondary waveguides on the acoustic vibration is added to the vibration loop equation as the acoustic load of the vibration loop. The vibration loop equation is rewritten as:

[0078]

[0079] in, K ms =K m , S D is the equivalent area of ​​the speaker cone

[0080] S24. Considering all loops of the speaker device, the mathematical model is shown in the following differential equations:

[0081]

[0082] In one embodiment, in step S3, the mathematical model is solved to obtain the sound pressure at different frequency points of the speaker, and the sound pressure level at different frequency points is calculated based on the sound pressure to obtain a sound pressure level curve of the speaker system.

[0083] In one embodiment, the sound pressure level curve obtained in step S3 is compared to see whether the curve satisfies the desired radiation sound field. If not, new structural parameters of the main and auxiliary waveguides are set, and the process returns to step S1. According to step S2, a new sound pressure level curve is re-solved and compared with the desired radiation sound field. This process is repeated until a sound pressure level curve that satisfies the desired radiation sound field is obtained, and the corresponding structural parameters of the main and auxiliary waveguides are maintained.

[0084] In one embodiment, the structural parameters of the main and auxiliary waveguide tubes include cross-sectional area, variable curvature, and length.

[0085] In one embodiment, when redesigning the structural parameters of the waveguide, only one of the parameters is changed, and the other parameters remain unchanged.

[0086] In one embodiment, step S3 specifically includes:

[0087] S31, initialize the differential equations, set the parameters of the speaker unit, and substitute the radiation impedances of the main and auxiliary waveguides obtained in step S1 into the differential equations.

[0088] S32, using the forward Euler method to solve the differential equations,

[0089] The input and output of the speaker system are shown below,

[0090] y=AX

[0091] Where A=[0 1 0], X T =[X1 X2 X3] = [i(t) x(t) dx / dt]; vector X satisfies the following relationship

[0092]

[0093] in, i(t), x(t), and dx / dt are the time-varying relationships of current, displacement, and velocity, respectively. m is the mass of the diaphragm and voice coil, R m is the vibration impedance, K m is the elastic force coefficient of the elastic component;

[0094] In the discrete time domain, the differential form is written as a first-order forward difference form, and the above relationship is rewritten as

[0095] X(n+1)=(ΔT·F+1)X(n)+ΔT·GU

[0096] Where X(n) T =[X1(n)X2(n)X3(n)], where X1(n), X2(n), and X3(n) are the woofer current, woofer cone displacement, and woofer cone vibration velocity, respectively; 1 is a unit vector; and ΔT is the sampling interval.

[0097] S33. Solve the sound pressure radiated by the loudspeaker

[0098] According to step S32, the vibration velocity of the speaker unit diaphragm is obtained, that is, X3(n), and then the volume velocity of the entire radiation surface of the speaker is obtained. X3(n)S d , recorded as U i ;

[0099] Among them S d is the effective radiation area of ​​the loudspeaker,

[0100] The cavity is divided into multiple sections. After passing through the first section of the cavity, the volume velocity U1 is

[0101]

[0102] Where ΔL1 is the length of the first cavity, U0 is the volume velocity before passing through the first cavity;

[0103] By analogy, the volume velocity of each cavity is calculated step by step until the volume velocity U at the connection between the main waveguide and the auxiliary waveguide is obtained. i

[0104]

[0105] Among them, U i-1 is the volume velocity before passing through the cavity;

[0106] S34. At the connection between the main waveguide and the auxiliary waveguide, the sound pressure continuity condition is met

[0107] p i +p r =p t =p b

[0108] Among them, p n is the incident radiation sound wave at the connection between the main and auxiliary waveguides, p r is the reflected sound wave, p t is the sound wave in the main waveguide, p b is the sound wave in the secondary waveguide

[0109] The corresponding volume velocity also satisfies the continuity condition

[0110] U i +U r =U t +U b

[0111] Among them, U i is the incident volume velocity at the junction of the main and auxiliary waveguides, U r is the reflection volume velocity, U t is the volume velocity in the main waveguide, U b is the sound wave in the secondary waveguide;

[0112] S35. Substituting the particle velocity v = p / 0c0 into the above formula, we can get

[0113]

[0114] Among them, p is the sound pressure at the particle position, ρ0 is the density of the medium in which the sound wave propagates, c0 is the speed of the sound wave propagating in the air, S L is the cross-sectional area of ​​the main and auxiliary waveguides when they are not separated, S is the cross-sectional area of ​​the main waveguide, and Z b0 is the total radiation impedance of the secondary waveguide and the radiation opening;

[0115] S36. Substituting the sound pressure continuity condition equation into the above formula, we can get

[0116]

[0117] where p ai The incident radiation sound pressure at the connection between the main and auxiliary waveguides, p ar is the reflected sound pressure

[0118] Solving the above equation can obtain the sound pressure reflection coefficient r p

[0119]

[0120] Similarly, the transmission coefficient p at is the sound pressure in the main waveguide.

[0121] Combined with the steps of S2, the volume velocity after passing through the main waveguide is calculated step by step until the last section, that is, the volume velocity after the nth section of the main waveguide U n for

[0122]

[0123] Among them, U n is the volume velocity after passing through the nth section of the main waveguide, Z n is the radiation resistance of the nth main waveguide tube entrance, U n-1 is the volume velocity after passing through the n-1th section of the main waveguide;

[0124] Finally, calculate the radiation sound pressure p of the entire speaker system at different frequency points

[0125]

[0126] The sound pressure at different frequency points is obtained, and then the sound pressure level is calculated to obtain the sound pressure level curve.

[0127] A third aspect of the present invention provides a design system for the above-mentioned vehicle-mounted woofer speaker device, comprising:

[0128] The waveguide radiation impedance design module introduces the transmission line theory model and uses distributed parameters to discretize and calculate the acoustic impedance of a waveguide with a variable cross-section.

[0129] The mathematical model of the loudspeaker system takes into account the influence of the radiation impedance of the waveguide. The radiation impedance of the waveguide will affect the vibration characteristics of the loudspeaker unit and also the radiation sound field characteristics of the loudspeaker system.

[0130] The speaker system solution module uses a time-domain state-space model to solve the speaker system's differential equations, construct a coefficient matrix, and introduce a first-order difference equivalent formula to obtain a progressive solution expression.

[0131] The speaker system optimization module compares the error between the calculated sound pressure level curve and the target curve and adjusts the waveguide structural parameters based on the change in error. During the parameter resetting process, it is possible to keep most parameters unchanged and change only one parameter, either increasing or decreasing it. If the error increases, the parameter needs to be adjusted in the opposite direction.

[0132] The present invention adopts the above solution and has the following advantages compared with the prior art:

[0133] The bass speaker device of the present invention uses a main waveguide and a sub-waveguide. When the paper cone moves downward, the air is compressed to generate sound waves. The sound waves enter the cavity and are compressed again. Then, they are radiated outward through the main waveguide and the sub-waveguide, thereby improving the sensitivity of the speaker device, making the low-frequency extension more obvious, and improving the sound pressure level at the low frequency. In the design method of the present invention, the design concept of the waveguide is introduced into the dual-channel ventilated vehicle-mounted bass speaker system. Compared with the existing design scheme based on the Helmholtz resonator, it has a higher degree of design freedom and more adjustable and controllable parameters; an analytical calculation method for the radiation impedance of the waveguide based on the transmission line theory is proposed, which can be applied to various waveguides with variable cross-sections and has good guiding significance for actual engineering operations; a small signal parameter mathematical model of the speaker system considering the radiation impedance of the waveguide is given, which can calculate the influence of the radiation impedance of the waveguide on the vibration characteristics of the speaker unit; the present invention provides a method for iteratively calculating the radiated sound field of the waveguide using a state-space equation, which is beneficial to engineering calculations and has practical value; and an optimization design method for the dual-channel ventilated vehicle-mounted bass speaker device is provided. The structural parameters of the main and auxiliary waveguides are adjusted by changing the size of the error in combination with the latest error iteration criterion. This method has practical engineering significance and is very beneficial to actual operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0134] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0135] Figure 1a is a three-dimensional schematic diagram of a woofer speaker device according to an embodiment of the present invention;

[0136] Figure 1b yes Figure 1a A three-dimensional schematic diagram of the woofer device shown in another perspective;

[0137] Figure 2 is a front schematic diagram of a box according to an embodiment of the present invention;

[0138] Figure 3 is a three-dimensional schematic diagram of a woofer according to an embodiment of the present invention;

[0139] Figure 4 yes Figure 1a to Figure 1b a schematic diagram of the back of the woofer unit shown;

[0140] Figure 5 yes Figure 4 Cross-sectional view along the AA axis;

[0141] Figure 6 is a perspective schematic diagram of a woofer speaker device according to this embodiment, wherein the rear cover is not shown;

[0142] Figure 7 yes Figure 6 a schematic diagram of the back of the woofer unit shown;

[0143] Figures 8a to 8d Schematic diagrams of several waveguides according to embodiments of the present invention are respectively shown;

[0144] Figure 9 3 is a comparison diagram of frequency response curves of a single waveguide woofer device and a woofer device of this embodiment.

[0145] In the above figures,

[0146] 1. Box body; 10. Rear cover; 100. Outlet pipe; 11. First partition; 12. Second partition; 13. Third partition; 131. Gap; 14. Fourth partition; 141. Gap;

[0147] 2. Woofer; 20. Cone; 21. Cone stand; 210. Through hole; 22. Magnetic circuit system; 23. Bracket; 230. Through hole; 24. Voice coil; 25. Centering support

[0148] 3. Cavity; 31. Main waveguide tube; 311. Entrance; 312. Exit; 32. Secondary waveguide tube; 321. Entrance; 322. Exit. DETAILED DESCRIPTION

[0149] The preferred embodiments of the present invention are described in detail below 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.

[0150] This embodiment provides a vehicle-mounted bass speaker device with dual waveguides. Figure 1a 、 Figure 2 and Figure 3 As shown, the vehicle-mounted woofer speaker device mainly includes a box body 1 and a woofer speaker 2. The woofer speaker 2 is arranged in the box body 1. Figures 1a to 8dAs shown, the woofer 2 includes a paper cone 20 having a front surface facing the interior of the vehicle cabin and a rear surface opposite thereto. The forward sound waves of the woofer 2 radiate into the free space inside the vehicle cabin. A cavity 3 is formed between the rear surface of the paper cone 20 and the enclosure 1. A main waveguide 31 is provided within the enclosure 1 for connecting the cavity 3 to the outside. A secondary waveguide 32 is also provided within the enclosure 1. The main waveguide 31 and the secondary waveguide 32 have inlets 311 and 321, respectively, that communicate with the cavity 3. The main waveguide 31 has an outlet 312 for communicating with the exterior of the vehicle cabin, and the secondary waveguide 32 has an outlet 322 for communicating with either the exterior or the interior of the vehicle cabin. Specifically, in this embodiment, the outlets 312 and 322 of the first waveguide 31 and the secondary waveguide 32 both communicate with the exterior of the vehicle cabin. The forward-radiated sound field of the woofer 2 and the sound field radiated by the two waveguides are separated by a baffle. The baffle can be a sealed sheet metal between the vehicle trunk and the car compartment, or a sealed sheet metal between the bottom plate and the car compartment. Through holes are opened on the sheet metal as radiation holes for the two waveguides.

[0151] like Figure 5 As shown, the paper basin 20 is fixedly mounted on the basin frame 21. The front end of the box body 1 is open, and the outer periphery of the basin frame 21 is fixedly connected to the front end of the box body 1. A rear cover 10 is provided at the rear end of the box body 1, and the outlets 312 and 322 of the main waveguide tube 31 and the auxiliary waveguide tube 32 are respectively provided on the rear cover 10. Specifically, an outlet pipe portion 100 extending backward is formed in the middle portion of the rear cover 10, and the outlet pipe portion 100 forms the above-mentioned two outlets 312 and 322. The outlet pipe portion 100 can pass through the above-mentioned sheet metal parts and connect to the outside of the car. The directional words "front" and "rear" mentioned in this article are defined for the convenience of description, corresponding to Figure 5 The lower and upper sides of the middle paper.

[0152] Combine Figure 2 and Figures 5 to 7 As shown, a first baffle 11 is fixedly installed in the cabinet 1. The first baffle 11 is located between the woofer 2 and the rear cover 10, thereby forming a cavity 3 in front of the first baffle 11. A main waveguide 31 and a secondary waveguide 32 are formed between the first baffle 11 and the rear cover 10, and the inlets 311 and 321 of each waveguide are respectively provided on the first baffle 11. In this embodiment, the first baffle 11 is arranged horizontally, and its outer periphery is fixedly connected to the side wall of the cabinet 1, or the two are integrally formed.

[0153] The box body 1 is further provided with a second partition 12, a third partition 13 and a fourth partition 14. The second partition 12 divides the space between the first partition 11 and the rear cover 10 into a first space portion and a second space portion. The third partition 13 divides the first space portion into a main waveguide 31, and the fourth partition 14 divides the second space portion into a secondary waveguide 32. Figure 6 and Figure 7As shown, the third and fourth baffles 13, 14 are both arc-shaped, with the two arcs sharing a common center. The radius of the third baffle 13 is smaller than that of the fourth baffle 14. The leading ends of the third and fourth baffles 13, 14 are respectively connected to the second baffle 12. Gaps 131 and 141 are formed between the trailing ends of the third and fourth baffles 13, 14, and the second baffle 12, connecting the corresponding waveguide outlets 312, 322. The leading end of the fourth baffle 14 is adjacent to the trailing end of the third baffle 13. The second baffle 12 is generally vertically disposed and further divides the outlet tube portion 100 of the rear cover 10 into two parts, forming the outlets 312, 322 of the main waveguide 31 and the outlets 312, 322 of the auxiliary waveguide 32, respectively.

[0154] In this embodiment, the main waveguide 31 serves as the main waveguide, and the auxiliary waveguide 32 serves as the auxiliary waveguide. The areas of the inlet 311 and outlet 312 of the main waveguide 31 are respectively larger than the areas of the inlet 321 and outlet 322 of the auxiliary waveguide 32. Furthermore, the cross-sectional area of ​​the middle portion of the main waveguide 31 is larger than the cross-sectional area of ​​the middle portion of the auxiliary waveguide 32, and smaller than the areas of the respective inlets 311, 321 and outlets 312, 322. This results in the cross-sectional areas of the main waveguide 31 and auxiliary waveguide 32, perpendicular to the airflow direction, first decreasing and then increasing.

[0155] like Figure 5 As shown, the basin frame 21 is a hollow basin frame 21, which is provided with multiple and various through-holes for airflow. The magnetic circuit system 22 of the woofer 2 is mounted on the front side of the paper cone 20. The rear end of the voice coil 24 of the woofer 2 is connected to the paper cone 20, and the front end of the voice coil 24 is inserted into the magnetic gap formed by the magnetic circuit system 22. The magnetic circuit system 22 is mounted on the basin frame 21 via a bracket 23, which is also provided with through-holes 230 for airflow. The woofer 2 also includes a centering support 25, which is fixedly mounted on the rear end of the voice coil 24. The centering support 25 is located on the rear side of the paper cone 20, and the outer periphery of the centering support 25 is also fixedly connected to the basin frame 21.

[0156] like Figure 8a As shown, the cross-sectional area of ​​the main waveguide tube 31 and the auxiliary waveguide tube 32 can be constant. Figure 8b As shown, the cross-sectional areas of the main waveguide tube 31 and the auxiliary waveguide tube 32 can be gradually increased along the airflow direction. Figure 8c As shown, the cross-sectional area of ​​the main waveguide tube 31 and the auxiliary waveguide tube 32 can be gradually reduced along the airflow direction. Figure 8d As shown, the cross-sectional areas of the main waveguide tube 31 and the auxiliary waveguide tube 32 can be reduced first and then increased. This embodiment adopts this type of main waveguide tube 31 and auxiliary waveguide tube 32.

[0157] In this woofer speaker device, the woofer 2 is mounted upside down within the enclosure 1, reducing the overall size of the speaker device and making the structure relatively compact. The main waveguide 31 and auxiliary waveguide 32 are not linear channels, but rather resemble a "spiral" shape. As the cone 20 moves downward, it compresses the air, generating sound waves. These waves enter the cavity 3, are compressed again, and then radiate outward through the main waveguide 31 and auxiliary waveguide 32, enhancing the sensitivity of the speaker device.

[0158] This embodiment also provides a design example. First, the small signal parameters of the woofer are as follows: R e =2.02ohm, inductor L e =0.288mH, resonant frequency f s =50.4Hz, vibration mass M ms =50.258g, damping R ms =1.347kg / s, elastic coefficient K of the vibration system ms =5.05N / mm, electromagnetic driving force coefficient Bl = 2.826N / A. Secondly, set the length and cross-sectional area variation characteristics of the main waveguide and the auxiliary waveguide, and calculate the acoustic impedance of the main waveguide and the auxiliary waveguide, such as Figures 8a to 8d Then, based on the calculated acoustic impedance, the mathematical model of the woofer device is obtained as shown below:

[0159]

[0160] The differential equations are solved to calculate the radiated sound field of the speaker device. The obtained radiated sound field is compared with the expected radiated sound field. The error between the calculated sound pressure level curve and the target curve is compared. According to the change in the error, the structural parameters of the main and auxiliary waveguides are adjusted.

[0161] Performance tests were conducted on a conventional single-waveguide woofer device and a woofer device according to this embodiment. The signal parameters of the woofers used in both devices are as follows: DC resistance R_e = 2.02 ohm, inductance L_e = 0.288 mH, resonant frequency f_s = 50.4 Hz, vibrating mass M_ms = 50.258 g, damping R_ms = 1.347 kg / s, elastic modulus K_ms = 5.05 N / mm, and electromagnetic driving force coefficient Bl = 2.826 N / A. The performance tests were conducted in a semi-anechoic chamber. The woofer device was mounted on a baffle with an opening that matched the diameter of the speaker's radiation outlet. A B&K 4189 microphone was placed 1 meter from the speaker to collect the speaker's output signal. The speaker and microphone were at the same level. A power amplifier and a Klippel R&D measurement system were also used in the experiments.

[0162] The test results are as follows Figure 9 As shown in the figure, the thin line is the frequency response curve of the existing single-channel Helmholtz resonator speaker device; the thick line is the frequency response curve of the dual-waveguide woofer speaker device of this embodiment. As can be seen from the figure, the low-frequency extension of the woofer speaker device of this embodiment is more obvious, as shown in FIG. Figure 9 At point A in FIG. 1 , the woofer speaker device of this embodiment has a higher sound pressure level at low frequencies.

[0163] The above embodiment is intended only to illustrate the technical concepts and features of the present invention and is a preferred embodiment. Its purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. It is not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A vehicle-mounted woofer speaker device, comprising a housing and a woofer speaker disposed within the housing, the woofer speaker including a paper cone having a front surface facing the interior of the vehicle compartment and a rear surface opposite thereto, a cavity formed between the rear surface of the paper cone and the housing, a main waveguide disposed within the housing for connecting the cavity to the exterior, and characterized in that: The box body is further provided with a secondary waveguide, the main waveguide and the secondary waveguide respectively having an inlet communicating with the cavity, the main waveguide having an outlet for communicating with the outside of the compartment, and the secondary waveguide having an outlet for communicating with the outside of the compartment; The paper basin is arranged on a basin stand, the front end of the box is open, the basin stand is connected to the front end of the box, the rear end of the box is provided with a rear cover, and the outlets are respectively provided on the rear cover; A first baffle is provided in the box, and the first baffle is located between the woofer and the rear cover so as to form the cavity on the front side of the first baffle. The main waveguide and the auxiliary waveguide are formed between the first baffle and the rear cover, and the inlets are respectively provided on the first baffle. A second partition, a third partition and a fourth partition are further provided in the box body, the second partition divides the space between the first partition and the rear cover into a first space part and a second space part, the third partition divides the first space part into the main waveguide tube, and the fourth partition divides the second space part into the auxiliary waveguide tube; wherein, an outlet pipe portion extending rearward is formed in the middle portion of the rear cover, the second partition divides the outlet pipe portion into two parts, serving as outlets of the main waveguide tube and the auxiliary waveguide tube respectively, and the outlet pipe portion is configured to pass through a through hole in a sealing sheet metal between the vehicle trunk and the vehicle compartment or a sealing sheet metal between the vehicle floor and the vehicle compartment, so that the main waveguide tube and the auxiliary waveguide tube are connected to the outside of the vehicle; The third partition plate and the fourth partition plate are both arc-shaped, the two arcs have a common center, and the radius of the third partition plate is smaller than the radius of the fourth partition plate. The leading end of the third partition plate and the leading end of the fourth partition plate are respectively connected to the second partition plate. A gap communicating with the corresponding waveguide tube outlet is formed between the trailing ends of the third partition plate and the fourth partition plate and the second partition plate, wherein the leading end of the fourth partition plate is adjacent to the trailing end of the third partition plate, so as to form a main waveguide tube and a secondary waveguide tube as a spiral channel. The cross-sectional area of ​​the middle portion of the main waveguide tube and the cross-sectional area of ​​the middle portion of the auxiliary waveguide tube are respectively smaller than the areas of their respective inlets and outlets, so that the cross-sectional areas of the main waveguide tube and the auxiliary waveguide tube perpendicular to the airflow direction first decrease and then increase.

2. The vehicle-mounted woofer speaker device according to claim 1, wherein: The magnetic circuit system of the woofer is installed on the front side of the paper cone, the rear end of the voice coil of the woofer is connected to the paper cone, and the front end of the voice coil is inserted into the magnetic gap formed by the magnetic circuit system.

3. The vehicle-mounted woofer speaker device according to claim 2, wherein: The magnetic circuit system is mounted on the basin frame through a bracket, and the bracket is provided with a through hole for airflow; the woofer also includes a centering support plate, which is fixedly arranged at the rear end of the voice coil, and the centering support plate is located on the rear side of the paper cone. The outer periphery of the centering support plate is mounted on the basin frame through a bracket, and the basin frame is provided with a through hole for airflow.

4. A method for designing a vehicle-mounted woofer speaker device, characterized in that: The vehicle-mounted woofer speaker device is the vehicle-mounted woofer speaker device according to any one of claims 1 to 3, and the design method comprises the following steps: S1. Select a main waveguide and a secondary waveguide, and calculate the total radiation impedance of the selected main waveguide and the secondary waveguide; S2. Construct a model of the loudspeaker device according to the radiation impedances of the main waveguide and the auxiliary waveguide obtained in step S1. The model is represented by the following differential equations: Among them, U(t) is the voltage output by the front-end amplifier of the speaker unit, R e is the DC resistance of the voice coil, i(t) is the current in the voice coil, L e is the inductance of the voice coil, Bl is the electromagnetic induction coefficient, v(t) is the movement speed of the voice coil, M ms is the vibration mass of the loudspeaker vibration system, R ms is the vibration resistance of the loudspeaker vibration system, K ms is the stiffness coefficient of the loudspeaker vibration system, is the relationship between the vibration acceleration of the loudspeaker vibration system and time. is the relationship between the vibration velocity of the loudspeaker vibration system and time, X(t) is the relationship between the vibration displacement of the loudspeaker vibration system and time, and t is time; S3, calculating the radiated sound field of the speaker device according to the model established in step S2; S4, comparing the radiated sound field obtained in step S3 with the expected radiated sound field. If the expected radiated sound field is satisfied, determining that the main waveguide and the auxiliary waveguide meet the design requirements; if the expected radiated sound field is not satisfied, adjusting the structures of the main waveguide and the auxiliary waveguide; Wherein, in the step S1, the total radiation impedance is calculated according to the following formula: Z1=R b0 +jωM b0 +R a0 +jωM a0 Where R a0 is the main waveguide radiation resistance, M a0 is the main waveguide radiation quality, R b0 is the radiation resistance of the secondary waveguide, M b0 is the radiation quality of the secondary waveguide, j is the imaginary unit, and ω is the angular frequency; The step S3 specifically includes: S3-1, initializing the differential equation group, setting the parameters of the woofer, and substituting the total radiation impedance Z1 obtained in step S1 into the differential equation group; S3-2, using the forward Euler method to solve the differential equations, The input and output of the woofer are shown below, y=AX Where A=[0 1 0], X T =[X1 X2 X3] = [i(t)x(t)dx / dt], the vector X satisfies the following relationship in i(t), x(t), and dx / dt are the time-varying relationships of current, displacement, and velocity, respectively. m is the mass of the diaphragm and voice coil, R m is the vibration impedance, K m is the elastic force coefficient of the elastic component; In the discrete time domain, the above relationship is rewritten as the following first-order forward difference form: X(n+1)=(ΔT·F+1)X(n)+ΔT·GU, where X(n) T =[X1(n)X2(n)X3(n)], where X1(n), X2(n), and X3(n) are the woofer current, woofer cone displacement, and woofer cone vibration velocity, respectively; 1 is a unit vector; and ΔT is the sampling interval. S3-3. Solve the sound pressure radiated by the loudspeaker. According to the vibration velocity X3(n) of the woofer cone, the volume velocity X3(n)S of the entire radiation surface of the woofer is obtained. d , recorded as U i , where S d is the effective radiation area of ​​the loudspeaker, The cavity is divided into multiple sections. After passing through the first section of the cavity, the volume velocity U1 is Where ΔL1 is the length of the first cavity, U0 is the volume velocity before passing through the first cavity; By analogy, the volume velocity of each cavity is calculated step by step until the volume velocity U at the connection between the main waveguide and the auxiliary waveguide is obtained. i Among them, U i-1 is the volume velocity before passing through the cavity; S3-4. At the connection between the main waveguide and the auxiliary waveguide, the sound pressure continuity condition is met p i +p r =p t =p b Among them, p i is the incident radiation sound pressure at the connection between the main and auxiliary waveguides, p r is the reflected sound pressure, p t is the sound pressure in the main waveguide, p b is the sound pressure in the secondary waveguide; The corresponding volume velocity also satisfies the continuity condition IN i +U r =U t +U b Among them, U i is the incident volume velocity at the junction of the main and auxiliary waveguides, U r is the reflection volume velocity, U t is the volume velocity in the main waveguide, U b is the sound wave in the secondary waveguide; S3-5. Substituting the particle velocity v = p / ρ0c0 into the above formula, we can get Among them, p is the sound pressure at the particle position, ρ0 is the density of the medium in which the sound wave propagates, c0 is the speed of the sound wave propagating in the air, S L is the cross-sectional area of ​​the main and auxiliary waveguides when they are not separated, S is the cross-sectional area of ​​the main waveguide, and Z b0 is the total radiation impedance of the secondary waveguide and the radiation opening; S3-6. Substituting the sound pressure continuity condition equation into the above formula, we can obtain where p ai The incident radiation sound pressure at the connection between the main and auxiliary waveguides, p ar is the reflected sound pressure; Solving the above equation can obtain the sound pressure reflection coefficient r p Similarly, the transmission coefficient p at is the sound pressure in the main waveguide; Calculate the volume velocity after passing through the main waveguide step by step until the last section, that is, the volume velocity U after the nth section of the main waveguide n for Among them, U n is the volume velocity after passing through the nth section of the main waveguide, Z n is the radiation resistance of the nth main waveguide tube entrance, U n-1 is the volume velocity after passing through the n-1th section of the main waveguide; Finally, calculate the radiated sound pressure p of the entire woofer device at different frequencies The sound pressure at different frequency points is obtained, and then the sound pressure level is calculated to obtain the sound pressure level curve.

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