Notification device

Abstract

To provide a notification device capable of securing sound volume in a desired direction and simultaneously reducing sound volume in other directions.SOLUTION: A notification device includes: a sounder 2 for generating sound; and a housing 3 for holding the sounder 2. The housing 3 includes: a case 4 where a sound emission hole 44 for emitting sound generated by the sounder 2 to an outside is formed; and an impedance adjustment section 5 for adjusting acoustic impedance of the housing 3. Since a sound pressure of the sound to be emitted from the housing 3 is changed by the acoustic impedance of the housing 3, the acoustic impedance of the housing 3 is adjusted, thereby to secure sound volume in a desired direction and simultaneously reduce sound volume in other directions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a notification device. [Background technology]

[0002] Electric vehicles and hybrid vehicles, which are quiet when traveling at a constant speed, are required to be equipped with and operate a notification device to alert those around them of the approach of the vehicle. The frequency of the notification sound is, for example, 630 to 1600 Hz. As described in Patent Document 1, for example, the sound generator used in the notification device includes a vibrating membrane that generates sound, a drive unit that drives the vibrating membrane, and a cylindrical case with a bottom that holds the vibrating membrane and the drive unit, and is configured to emit sound from a sound emission hole formed in the front part of the case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-25558 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable for a notification device to emit a sufficient volume of sound outside the vehicle while minimizing the volume entering the vehicle interior. However, in typical sound devices, the bottom and side walls of the case are thin, making it difficult to ensure sound insulation performance and reducing quietness inside the vehicle interior.

[0005] In view of the above, an object of the present invention is to provide a notification device that can ensure a volume in a desired direction while reducing the volume in other directions. [Means for solving the problem]

[0006] In order to achieve the above object, the invention of claim 1 provides a notification device comprising: a sound generating body (2) that generates a sound; and a housing (3) that holds the sound generating body. The housing comprises a case (4) formed with a sound emission hole (44) that emits the sound generated by the sound generating body to the outside; and an impedance adjustment unit (5) that adjusts the acoustic impedance of the housing. The case has a plate-shaped bottom (41), a cylindrical part (42) standing upright from the bottom, and a plate-shaped front part (43) covering the opening of the cylindrical part, the sound emission holes are formed in the front part, the impedance adjustment part has a wall part (51) covering the bottom, and an intermediate layer (53) made of a material different from that of the bottom and the wall part is formed between the bottom and the wall part, and the intermediate layer is sealed only by the case, the wall part, and the cylindrical part (52) standing upright from the outer edge of the wall part. do.

[0007] The sound pressure of the sound emitted from the housing varies depending on the acoustic impedance of the housing, so by adjusting the acoustic impedance of the housing, it is possible to ensure the volume in the desired direction while reducing the volume in other directions.

[0008] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a notification device according to a first embodiment. [Figure 2] FIG. 2 is an enlarged view of part II in FIG. [Figure 3] FIG. 10 is a cross-sectional view of a comparative example. [Figure 4] FIG. 10 is a diagram showing the measurement results of sound pressure. [Figure 5] FIG. 10 is a cross-sectional view of a reporting device according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a reporting device according to a second embodiment. [Figure 7] FIG. 10 is a cross-sectional view of a reporting device according to a second embodiment. [Figure 8] FIG. 10 is a cross-sectional view of a reporting device according to a third embodiment. [Figure 9] FIG. 10 is a cross-sectional view of a reporting device according to a third embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a reporting device according to a third embodiment. [Figure 11] FIG. 10 is a cross-sectional view of a reporting device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, parts that are identical or equivalent to each other will be denoted by the same reference numerals.

[0011] (First embodiment) A first embodiment will be described. The notification device of this embodiment is for notifying the surrounding area of an approaching vehicle, and includes a sound generator 1 shown in Fig. 1. The sound generator 1 includes a sound generator 2 that generates a sound, and a housing 3 that holds the sound generator 2.

[0012] The sound generator 2 includes a diaphragm 21 and a drive unit 22. The diaphragm 21 is a thin film in the shape of a hollow truncated cone that extends in the front direction of the housing 3. The drive unit 22 vibrates the diaphragm 21. The drive unit 22 is made up of a bobbin joined to the diaphragm 21 and a magnetic circuit unit that applies a magnetic field to a voice coil wound around the bobbin; by applying a magnetic field to the voice coil while passing a current, the bobbin is displaced, causing the diaphragm 21 to vibrate and generate sound.

[0013] The housing 3 includes a cylindrical case 4 with a bottom and an impedance adjustment section 5. The case 4 in this embodiment is a square cylindrical case with a bottom, and includes a rectangular plate-shaped bottom 41, a square cylindrical section 42 standing upright from the outer edge of the bottom 41, and a rectangular plate-shaped front section 43 that covers the opening of the cylindrical section 42. The sound generator 2 is disposed inside the case 4. The case 4 is made of resin.

[0014] Of the outer wall surfaces of the case 4, the outer wall surface of the bottom portion 41 is referred to as the back surface 41a. Of the outer wall surfaces of the case 4, the surface opposite the back surface 41a, i.e., the outer wall surface of the front surface portion 43, is referred to as the front surface 43a. Of the outer wall surfaces of the case 4, the surface connecting the front surface 43a and the back surface 41a, i.e., the outer wall surface of the tubular portion 42, is referred to as the side surface 42a. A sound emission hole 44 that opens to the front surface 43a is formed in the front surface portion 43, and sound generated by the sound generator 2 is emitted through the sound emission hole 44 to the outside of the housing 3 on the front surface 43a side.

[0015] In this embodiment, the case 4 is constructed as a single unit, but the case 4 may be constructed by combining a plurality of components. For example, the bottom portion 41 and the tubular portion 42 may be constructed as separate bodies. In this case, to ensure rigidity, it is desirable to join the bottom portion 41 and the tubular portion 42 by adhesive or the like along the entire periphery.

[0016] The impedance adjustment unit 5 adjusts the acoustic impedance of the housing 3. The impedance adjustment unit 5 of this embodiment is configured to increase the acoustic impedance of the rear part of the housing 3. Furthermore, the impedance adjustment unit 5 is configured to adjust the difference in acoustic impedance between the housing 3 and the air, thereby increasing the amount of sound generated by the sound generator 2 reflected by the housing 3 and reducing sound emitted to the outside.

[0017] Specifically, the impedance adjustment unit 5 includes a rectangular plate-shaped wall portion 51 that covers the rear surface 41a, and a square cylindrical tubular portion 52 that stands upright from the outer edge of the wall portion 51. The wall portion 51 and the tubular portion 52 are made of resin. The case 4, the wall portion 51, and the tubular portion 52 may be made of the same material, or may be made of different materials. The wall portion 51 has a higher material density than the bottom portion 41. The wall portion 51 is also formed to be thicker than the bottom portion 41.

[0018] The end of the cylindrical portion 52 opposite the wall portion 51 is joined to the bottom portion 41 by adhesive or the like, and an intermediate layer 53 made of a material different from that of the bottom portion 41 and the wall portion 51 is formed between the bottom portion 41 and the wall portion 51. In this embodiment, a gap is formed between the bottom portion 41 and the wall portion 51, and the intermediate layer 53 is made of air. The thickness of the intermediate layer 53 is, for example, 3 mm.

[0019] A gap may be formed between the cylindrical portion 52 and the case 4. In this case, for example, a rod-shaped member may be erected on the inner periphery of the wall portion 51, and this rod-shaped member may be glued to the bottom portion 41 to fix the wall portion 51 to the bottom portion 41, thereby reducing the transmission of vibration from the bottom portion 41 to the wall portion 51. Alternatively, a recess may be formed in the bottom portion 41, and a rod-shaped member erected on the wall portion 51 may be inserted into this recess to fix the wall portion 51 to the bottom portion 41, thereby reducing the transmission of vibration from the bottom portion 41 to the wall portion 51. This rod-shaped member may be made of, for example, rubber or hard urethane.

[0020] As described above, the sound generated by the sound generator 2 is emitted to the outside from the front surface 43a side of the housing 3 through the sound emission hole 44. The sound generated by the sound generator 2 also passes through the bottom portion 41 and the cylindrical portion 42 and is emitted to the outside from the back surface 41a side and the side surface 42a side of the housing 3.

[0021] 2, part of the sound traveling toward the bottom 41 is reflected by the inner wall surface of the bottom 41 as indicated by arrow A2, and the remainder passes through the bottom 41 as indicated by arrow A3 and is emitted to the intermediate layer 53. Part of the sound emitted to the intermediate layer 53 is reflected by the inner wall surface 51a of the wall 51 facing the bottom 41 as indicated by arrow A4, and the remainder passes through the wall 51 and is emitted to the outside of the housing 3 as indicated by arrow A5.

[0022] The greater the difference in impedance between the bottom 41 and the air and between the wall 51 and the air, the greater the amount of sound reflected. Also, the higher the density and thickness of the material that makes up the bottom 41 and the wall 51, the greater the acoustic impedance of these materials.

[0023] 3, sound generator 1 does not include impedance adjustment unit 5, and rear surface 41a of case 4 is exposed. In this comparative example, sound directed toward bottom 41 as indicated by arrow A6 is partially reflected by the inner wall surface of bottom 41 as indicated by arrow A7, and the remainder passes through bottom 41 and is emitted to the outside of housing 3 as indicated by arrow A8.

[0024] In this manner, in this embodiment, the rear surface 41a is covered by the wall portion 51, so that the number of times sound is reflected is greater than in the comparative example, and sound emission toward the rear surface 41a side of the housing 3 is reduced.

[0025] FIG. 4 shows the results of measurements of sound pressure around the sound generator conducted by the inventors. In FIG. 4, the solid line shows the measurement results for sound generator 1 of this embodiment, and the dashed line shows the measurement results for the comparative example. In this experiment, the frequency of the generated sound was 800 Hz. As shown in FIG. 4, in this embodiment, the sound pressure at the front was maintained at the same level as in the comparative example. On the other hand, the sound pressure at the back was reduced, being 8.9 dB lower than in the comparative example.

[0026] As described above, in this embodiment, by adjusting the acoustic impedance of the housing 3 using the impedance adjusting section 5, it is possible to ensure the volume in a desired direction while reducing the volume in other directions.

[0027] Furthermore, according to the above embodiment, the following effects can be obtained.

[0028] (1) The impedance adjusting unit 5 has a wall 51 that covers the bottom 41. This increases the acoustic impedance of the rear surface of the housing 3. In addition, a change in acoustic impedance is provided on the outside of the bottom 41, and the amount of sound reflected when sound generated inside the housing 3 passes through the rear surface of the housing 3 and heads toward the outside increases. Therefore, the sound pressure on the rear surface side of the housing 3 is reduced.

[0029] A sound generator placed inside the engine compartment needs to be compact, making it difficult to ensure a thick case. However, if the sound generator housing is constructed solely from a thin case, it is difficult to achieve a difference in volume between directions where volume is needed, such as the front, and directions where volume is not needed, such as the rear, especially for low-frequency sounds that transmit significantly. Furthermore, using special materials such as lead increases the manufacturing cost of the sound generator.

[0030] In contrast, in this embodiment, the increase in size of the housing occurs only in the portions where the wall portion 51 and the tubular portion 52 are provided. Furthermore, the wall portion 51 can be made of resin. Therefore, the increase in size can be kept to a minimum, and an increase in manufacturing costs can be suppressed.

[0031] (2) An intermediate layer 53 made of a material different from that of the bottom 41 and the wall 51 is formed between the bottom 41 and the wall 51. This increases the number of points where sound is reflected, increasing the volume of sound returning to the inside of the housing 3 and further reducing the sound pressure on the back side of the housing 3.

[0032] (3) The intermediate layer 53 is made of air. This increases the difference in acoustic impedance between the wall 51 and the intermediate layer 53, thereby increasing the amount of sound reflection and further reducing the sound pressure on the back side of the housing 3.

[0033] (4) The wall 51 has a material density higher than that of the bottom 41. As a result, the acoustic impedance of the outer wall 51 is higher than that of the inner bottom 41, increasing the volume of sound returning to the inside of the housing 3 and further reducing the sound pressure on the rear side of the housing 3.

[0034] (5) The wall 51 is formed to be thicker than the bottom 41. As a result, the acoustic impedance of the outer wall 51 is higher than that of the inner bottom 41, so the volume of sound returning to the inside of the housing 3 increases, and the sound pressure on the back side of the housing 3 is further reduced.

[0035] (Second embodiment) The second embodiment will be described. This embodiment is different from the first embodiment in that the distance between the bottom portion 41 and the wall portion 51 is changed, but the rest is the same as the first embodiment, so only the parts that are different from the first embodiment will be described.

[0036] In this embodiment, the distance between the bottom 41 and the wall 51 varies depending on the location. Specifically, one or both of the back surface 41a and the inner wall surface 51a are formed as a continuously curved surface, which allows a plurality of distances to be formed between the bottom 41 and the wall 51.

[0037] 5, by making the rear surface 41a a curved surface, multiple intervals are formed between the bottom 41 and the wall 51 as indicated by the arrows. Alternatively, both the rear surface 41a and the inner wall surface 51a may be curved. Alternatively, only the inner wall surface 51a may be curved.

[0038] Alternatively, one or both of the rear surface 41a and the inner wall surface 51a may have projections and recesses, thereby forming a plurality of intervals between the bottom portion 41 and the wall portion 51a.

[0039] For example, as shown in FIG. 6, by forming unevenness on the bottom 41 with a first convex portion 411 and a second convex portion 412 having a different protruding height than the first convex portion 411, three different spacings are formed between the bottom 41 and the wall portion 51, as shown by the arrows.

[0040] 7, three different intervals may be formed by forming a third convex portion 511 and a fourth convex portion 512 having a different protruding height from the third convex portion on the wall portion 51 so as to face the first and second convex portions 411 and 412. Alternatively, the bottom portion 41 may not be provided with any concaves and convexes, and only the wall portion 51 may be provided with concaves and convexes.

[0041] This embodiment has the same configuration and operation as the first embodiment, and can therefore obtain the same effects as the first embodiment.

[0042] Furthermore, according to the above embodiment, the following effects can be obtained.

[0043] (1) The distance between the bottom 41 and the wall 51 varies depending on the location. The frequency characteristics of the sound insulation effect are determined not only by the materials of the bottom 41, the wall 51, and the intermediate layer 53, but also by the distance between the bottom 41 and the wall 51. Therefore, by partially changing the distance between the bottom 41 and the wall 51 depending on the location, it is possible to obtain a sound insulation effect in multiple frequency bands.

[0044] (Third embodiment) The third embodiment will be described. This embodiment is the same as the first embodiment except that a configuration for consuming sound energy is added to the first embodiment. Therefore, only the differences from the first embodiment will be described.

[0045] In this embodiment, as shown in Fig. 8, the thermal conversion part 6 is disposed in the intermediate layer 53. The thermal conversion part 6 converts sound energy into thermal energy and consumes it. Specifically, the thermal conversion part 6 is made of a sound-absorbing material, and is disposed in the intermediate layer 53 by being bonded to the inner wall surface of the wall part 51 by adhesive or the like.

[0046] 9, the intermediate layer 53 may be made of resin or the like, and the heat conversion part 6 made of sound absorbing material may be placed on the intermediate layer 53 while being separated from the bottom part 41 and the wall part 51.

[0047] The thermal conversion unit 6 may also be configured so that the bottom 41 and the wall 51 are in contact with each other, and the bottom 41 and the wall 51 vibrate to cause friction at the contacting surfaces, thereby converting sound energy into thermal energy.

[0048] 10, a fifth convex portion 413 and a sixth convex portion 414 may be formed on the bottom portion 41, a seventh convex portion 513 may be formed on the wall portion 51, and the seventh convex portion 513 may be disposed between them so as to be in contact with the fifth and sixth convex portions 413, 414. When the thermal conversion portion 6 is formed with such fifth, sixth, and seventh convex portions 413, 414, 513, when the bottom portion 41 or the wall portion 51 vibrates due to sound, heat is generated by friction at the contact surface between the seventh convex portion 513 and the fifth and sixth convex portions 413, 414, and sound energy is converted into thermal energy.

[0049] This embodiment has the same configuration and operation as the first embodiment, and can therefore obtain the same effects as the first embodiment.

[0050] Furthermore, according to the above embodiment, the following effects can be obtained.

[0051] (1) A thermal conversion unit 6 that converts sound energy into heat energy and consumes it is disposed in the intermediate layer 53. Because sound is repeatedly reflected in the intermediate layer 53, by disposing the thermal conversion unit 6 in the intermediate layer 53 and converting sound energy into heat energy and consuming it, the sound pressure on the back side of the housing 3 is further reduced.

[0052] (Fourth embodiment) The fourth embodiment will be described. This embodiment is different from the first embodiment in that the configuration of the impedance adjustment unit 5 is changed, but the rest is the same as the first embodiment, so only the parts that are different from the first embodiment will be described.

[0053] In this embodiment, in addition to the back surface 41a of the case 4, the side surface 42a is also covered by the impedance adjusting portion 5. Specifically, as shown in Fig. 11 , the cylindrical portion 52 extends to cover the cylindrical portion 42, and its tip is joined to the end of the cylindrical portion 42 opposite to the bottom portion 41. A space is formed between the cylindrical portions 42 and 52, and an intermediate layer 53 is formed between the bottom portion 41 and the wall portion 51, and between the cylindrical portion 42 and the cylindrical portion 52.

[0054] This embodiment has the same configuration and operation as the first embodiment, and can therefore obtain the same effects as the first embodiment.

[0055] Furthermore, according to the above embodiment, the following effects can be obtained.

[0056] (1) The cylindrical portion 42 is covered by the cylindrical portion 52. This reduces sound pressure not only on the rear side of the housing 3 but also on the side of the housing 3. 。

[0057] (Other embodiments) The present invention is not limited to the above-described embodiments and can be modified as appropriate within the scope of the claims. Furthermore, the above-described embodiments are not unrelated to each other and can be combined as appropriate unless the combination is clearly impossible. It goes without saying that the elements constituting the embodiments are not necessarily essential unless specifically stated as essential or clearly considered essential in principle. Furthermore, when the numbers, values, amounts, ranges, etc. of the components of the embodiments are mentioned in the above-described embodiments, they are not limited to the specific numbers unless specifically stated as essential or clearly limited to a specific number in principle. Furthermore, when the shapes, positional relationships, etc. of the components are mentioned in the above-described embodiments, they are not limited to the shapes, positional relationships, etc., unless specifically stated or clearly limited to a specific shape, positional relationship, etc. in principle.

[0058] For example, in the third and fourth embodiments, a plurality of gaps may be provided between the bottom 41 and the wall 51 as in the second embodiment. Also, in the fourth embodiment, a heat conversion unit 6 may be provided as in the third embodiment. 。

[0059] Furthermore, in the first embodiment, the bottom portion 41 and the cylindrical portion 42 and the wall portion 51 and the cylindrical portion 52 are configured as separate bodies, but they may also be configured as an integrated body.

[0060] In the first embodiment, the impedance adjusting section 5 may have a laminated structure of a plurality of wall sections. That is, one or more wall sections may be laminated on the outside of the wall section 51. 。

[0061] In the first embodiment, the wall portion 51 and the bottom portion 41 may have the same material density, or the bottom portion 41 may have a higher material density than the wall portion 51. In the first embodiment, the wall portion 51 and the bottom portion 41 may have the same thickness, or the bottom portion 41 may be formed thicker than the wall portion 51. 。 [Explanation of symbols]

[0062] 2. Sounding body 3. Housing 4 cases 44 Sound emission hole 5 Impedance adjustment section

Claims

1. A reporting device, a sound generating body (2) that generates sound; a housing (3) that holds the sounding body, The housing includes: a case (4) having a sound emission hole (44) formed therein for emitting the sound generated by the sound generator to the outside; an impedance adjusting unit (5) that adjusts the acoustic impedance of the housing, The case is A plate-shaped bottom (41); A cylindrical portion (42) standing upright from the bottom portion; a plate-shaped front portion (43) that covers the opening of the cylindrical portion, The sound emission hole is formed in the front portion, The impedance adjustment unit includes a wall portion (51) that covers the bottom portion, An intermediate layer (53) made of a material different from that of the bottom and the wall is formed between the bottom and the wall, The intermediate layer is sealed only by the case, the wall portion, and a cylindrical portion (52) erected from the outer edge of the wall portion.

2. A reporting device as described in Claim 1, wherein the wall portion is made of a single material.

3. 2. The notification device according to claim 1, wherein the intermediate layer is made of air.

4. The reporting device according to claim 1 , wherein the bottom portion and the wall portion are separate bodies.

5. 4. The reporting device according to claim 1, wherein the wall portion is made of a material with a higher density than the bottom portion.

6. 4. The reporting device according to claim 1, wherein the wall portion is thicker than the bottom portion.

7. 4. The reporting device according to claim 1, wherein the distance between the bottom and the wall varies depending on the location.

8. The reporting device according to claim 7 , wherein one or both of an outer wall surface of the bottom portion and a surface of the wall portion facing the bottom portion are curved.

9. The reporting device according to claim 7 , wherein either or both of an outer wall surface of the bottom portion and a surface of the wall portion facing the bottom portion are formed with projections and recesses.

10. 4. The notification device according to claim 1, wherein the intermediate layer is provided with a heat conversion section (6) for converting sound energy into heat energy and consuming the heat energy.

11. The notification device according to claim 10, wherein the heat conversion section is made of a sound absorbing material.

12. the bottom and the wall are configured to contact each other; The notification device according to claim 10, wherein the thermal conversion unit is configured to convert sound energy into thermal energy by friction between the bottom and the wall at the contacting surfaces due to vibration.

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