Alarm bell

Abstract

To provide an alarm bell that can increase sound pressure of a bell sound that causes a gong.SOLUTION: An alarm bell 1 is equipped with a gong that produces a bell sound when struck and a striking rod 3 that strikes the gong, in which the gong has a slit 2e formed in its mouth edge 2d, and having an antinode in a position within an angle interval from 35 to 55 degrees in the peripheral direction from the slit 2e, and the striking rod 3 strikes a position within this angle interval. Further the striking rod 3 strikes a position at an angle interval θ of approximately 45 degrees from slit 2e, where the part that becomes the antinode of the vibration of the gong 2 is located.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an alarm bell in which a motor-driven striker strikes a gong to produce a bell sound. [Background technology]

[0002] An alarm bell comprises a gong that makes a sound when struck, a striker that strikes the gong, a motor that drives the striker, and a housing that houses the motor, and is used to ring and sound an alarm in the event of an emergency such as a fire (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-235394 Summary of the Invention [Problem to be solved by the invention]

[0004] The main uses of this type of alarm bell are as a district sounding device in an automatic fire alarm system or as an emergency bell in an emergency alarm system (hereafter simply referred to as "emergency bell"). Standards for emergency bells are set based on the Fire Service Act. One of these standards is sound pressure. Alarm bells used as emergency bells must meet the sound pressure standard.

[0005] Reducing the size of the alarm bell gong can reduce manufacturing costs, but simply reducing the size of the gong reduces the sound pressure, making it difficult to obtain the sound pressure required for use as an emergency bell.

[0006] SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an alarm bell that can increase the sound pressure of the bell sound produced by a gong. [Means for solving the problem]

[0007] This invention produces a bell sound when struck. Circular in plan view a gong and a hammer for striking the gong; a motor that drives the striking rod; an alarm bell comprising: The circumferential side On the rim , arranged at equal angular intervals around the circumference The slit Just two As it is formed, On the other hand Positions within the circumferential range of 35 to 55 degrees from the slit Gong The hitting rod has a portion that becomes an antinode of vibration, 35 to 55 degrees The alarm bell is characterized by striking a position within an angular interval of

[0008] The striking rod has a portion that serves as an antinode of vibration of the gong. On the other hand The impact may be applied to positions spaced at angular intervals of approximately 45 degrees from the slit in the circumferential direction.

[0009] In addition, this invention ,before The housing that houses the motor Gu The housing may further include a plurality of curved wall portions, which are bent in a V-shape in a plan view, in the circumferential direction and form part of the peripheral wall thereof.

[0010] The curved wall portions may have substantially the same shape and may be disposed at substantially equal intervals in the circumferential direction. The housing may be Y-shaped or cross-shaped in plan view. The housing may have a plurality of branch spaces formed therein, and the motor and a power transmission unit that transmits power to the striking rod may be disposed and housed in the branch spaces.

[0011] The present invention can further include a mounting plate for mounting the alarm bell at an installation position, and the gong can have an outer diameter that exposes an insertion hole for a fixing member provided at an end of the mounting plate when mounted. The housing can have an opening on its back side and a lid for closing the opening, and an insulating sheet can be provided between the opening and the lid to seal the opening. [Effects of the Invention]

[0012] According to this invention, the striking rod strikes a position within an angular range of 35 to 55 degrees circumferentially from the slit, where the antinode of the gong's vibration is located. This improves the efficiency of the gong's vibration caused by the strike, and increases the sound pressure of the chime produced by the gong. [Brief explanation of the drawings]

[0013] [Figure 1] 1 shows an example of an embodiment of the alarm bell of the present invention, and is a rear view (with the back cover of the housing open) showing the inner side (rear side) of the alarm bell. FIG. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] FIG. [Figure 4] This shows an example of an installation form when the above alarm bell is installed as a rainproof type, and is a surface view showing the alarm bell, mounting plate, and the surface of the wall on which it is to be installed. [Figure 5] 6 is a cross-sectional view of the alarm bell, the mounting plate, and the wall surface side portion of the installation object (wall surface, switch box, etc.), taken along the line EE in FIG. 5. FIG. [Figure 6] FIG. 2 is an exploded perspective view of the alarm bell, the mounting plate, and the wall-side portion of the installation target (wall, switch box, etc.). DETAILED DESCRIPTION OF THE INVENTION

[0014] An example of an embodiment of an alarm bell of the present invention will be described with reference to the drawings. The alarm bell of the present invention can be used, for example, as a district sounding device in an automatic fire alarm system or as an emergency bell in an acoustic device in an emergency alarm system.

[0015] <Basic configuration> The alarm bell 1 comprises a gong 2 that produces a bell sound when struck, a striking rod 3 that strikes the gong 2, a motor 4 that drives the striking rod 3, a cam 5 that is fixed to the drive shaft 4a of the motor 4 and rotates together with the drive shaft 4a, a power transmission unit 6 that is connected to the striking rod 3 and the cam 5 and transmits the power of the motor 4 to the striking rod 3, and a housing 7 that houses the motor 4 and other components (see Figures 1 to 3).

[0016] <Gong> The gong 2 has a bottom 2b and a peripheral portion 2c, and is shaped like a shallow, circular bowl in plan view. A space 2a is formed on the inside surface of the gong, surrounded by the peripheral portion 2c. The housing 7 is positioned within the space 2a so that the striking rod 3 strikes the inner surface of the peripheral portion 2c from the inside. Specifically, a fixing portion 2ba for fixing the housing is provided on the inner surface of the bottom 2b (see Figures 2 and 3), and the housing 7 is fixed to the fixing portion 2ba. A slit 2e is formed in the rim 2d of the peripheral portion 2c. In the illustrated example, two slits 2e are formed, one at each 180-degree circumferential position of the peripheral portion 2c.

[0017] <Dashing stick> The striking rod 3 is disposed so that the striking portion 3a at the tip thereof strikes the inner surface of the circumferential portion 2c of the gong 2 when the striking rod 3 moves forward in the longitudinal direction (towards the gong 2).

[0018] <Motor> The motor 4 is disposed so that the drive shaft 4a is oriented at a substantially right angle to the longitudinal direction of the hitting rod 3. A cam 5 is provided around the drive shaft 4a, which rotates together with the drive shaft 4a.

[0019] <Power transmission section> The power transmission unit 6 consists of a linear member whose tip end is connected to the batter 3 at connection part 6a and whose rear end is connected to the cam 5 at connection part 6b, and is arranged so that the power of the rotational movement of the motor 4 is converted into power of reciprocating movement via the cam 5 and transmitted to the batter 3, moving the batter 3 back and forth in the longitudinal direction.

[0020] <Housing> ·Shape, arrangement The housing 7 has multiple curved wall portions 7aa that form part of its peripheral wall 7a and are bent in a V-shape in a plan view (widening toward the peripheral portion 2c of the gong 2). In the illustrated example, there are three curved wall portions 7aa, giving the housing 7 a Y-shape in a plan view. The multiple curved wall portions 7aa are substantially the same shape and are arranged at approximately equal intervals in the circumferential direction. The housing 7 of this shape is arranged approximately centrally in a plan view within the space 2a on the inner surface of the gong 2. Because the multiple curved wall portions 7aa are bent at an angle rather than a curve, the space 2a on the inner surface of the gong 2 can be enlarged and the direction in which the chime is reflected can be expanded.

[0021] The housing 7 also has a plurality of end walls 7ab that form part of the peripheral wall 7a and connect the curved wall portions 7aa. In the illustrated example, there are three end walls 7ab, corresponding to the number of curved wall portions 7aa. These end walls 7ab are also of approximately the same shape and are arranged approximately evenly around the circumference. The housing 7 also has a bottom wall 7b. The bottom wall 7b has a protrusion 7ba on its outer surface (and a recess on its inner surface) that is fixed to the fixing portion 2ba on the gong 2. The housing 7 is arranged in the above-mentioned manner within the space 2a on the inner surface of the gong 2 by fastening the protrusion 7ba to the fixing portion 2ba on the gong 2 with a screw 7bb.

[0022] The housing 7 further has a back cover 7g that closes the opening 7f on the back side, and in the illustrated example, an insulating sheet 7h is provided between the opening 7f and the back cover 7g (see FIG. 3). The insulating sheet 7h seals the opening 7f to prevent corrosive gases and the like from entering the interior 7c of the housing 7, thereby protecting the motor 4 and other components housed in the housing 7. The portion marked with a symbol on the outer surface of the back cover 7g is a hook 7i used to hang the alarm bell 1 on an object to which it is attached.

[0023] Equalizing the surrounding space Here, the peripheral wall 7a of the housing 7 has multiple curved wall portions 7aa that are V-shaped when viewed from above, and these curved wall portions 7aa are of approximately the same shape and are arranged in an approximately even circumferential direction.As a result, the spaces formed between these curved wall portions 7aa and the peripheral side portion 2c of the gong 2 in the space portion 2d on the inner surface of the gong 2 can also be formed in an approximately same shape and arranged in an approximately even circumferential direction.

[0024] -Improved sound pressure (due to housing shape, surrounding space, etc.) In the alarm bell 1 of this invention, the housing 7 has multiple curved wall portions 7aa that are V-shaped in plan view and form part of the peripheral wall 7a. This allows the curved wall portions 7aa to function as acoustic walls, improving the resonance effect within the space 2a inside the gong 2. Furthermore, by providing the multiple curved wall portions 7aa with substantially the same shape and uniformly spaced circumferentially, the spaces formed between the curved wall portions 7aa and the peripheral portion 2c of the gong 2 in the space 2d inside the gong 2 can also be formed with substantially the same shape and uniformly spaced circumferentially, as described above. This also improves the resonance effect within the space 2a inside the gong 2. Furthermore, using a housing 7 with a Y-shape in plan view, as shown in the example shown in the figure, can increase the sound pressure of the chime generated by the gong 2, as shown in the results of a sound pressure measurement experiment described below.

[0025] Sound pressure measurement experiment (compared to a planar L-shaped housing) The inventors conducted an experiment to measure the sound pressure of an alarm bell using a Y-shaped housing as in the present invention to house the motor and power transmission unit, and an alarm bell using an L-shaped housing as in the present invention. The experiment results showed that the sound pressure was higher in the alarm bell using a Y-shaped housing as in the present invention than in the alarm bell using an L-shaped housing as in the present invention. This result is believed to be due to the fact that, as mentioned above, in the alarm bell using a Y-shaped housing as in the present invention, the multiple curved walls function as acoustic walls, and the multiple curved walls are generally the same shape and are arranged in a generally uniform manner, and the spaces formed between the curved walls and the circumferential sides of the gong are also generally the same shape and are generally uniformly distributed in the circumferential direction, thereby improving the resonance effect in the space on the inner surface of the gong.

[0026] The inventors also analyzed the sound pressure distribution of the alarm bells used in the above-mentioned measurement experiments using a simulation program. The analysis revealed that, within the space inside the gong, the L-shaped housing resulted in uneven distribution of high-pressure areas, whereas the Y-shaped housing resulted in a roughly uniform radial distribution. Furthermore, outside the gong, the L-shaped housing resulted in high-pressure areas distributed around the periphery of the gong and areas in front of the gong that were also distributed off-center. The Y-shaped housing resulted in high-pressure areas distributed in a continuous ring around the periphery of the gong and areas in front of the gong that were concentrated toward the front. These results demonstrate that the use of a Y-shaped housing, as in the present invention, improves the resonance effect within the space inside the gong, thereby increasing the sound pressure of the gong.

[0027] Branch space A plurality of branch spaces 7cb-7cd are formed in the interior 7c of the housing 7 in accordance with the case shape. In the illustrated example, three branch spaces 7cb-7cd are formed branching off from the central space 7ca in accordance with the Y-shaped case shape in plan view. The shape of each of the branch spaces 7cb-7cd toward the tip end (the side facing the circumferential portion 2c of the gong 2) is generally rectangular in plan view.

[0028] The batting rod 3 penetrates the end wall 7ab of the branch space 7cb, with its rear end connecting portion 3b with the power transmission unit 6 located inside the branch space 7cb and its front end striking portion 3a located outside the branch space 7cb. The branch space 7cb, where the batting rod 3 is located, is connected to the adjacent branch space 7cc via a central space 7ca, forming a continuous V-shaped space in a plan view. The motor 4 and power transmission unit 6 are housed within this V-shaped space. Specifically, the motor 4 is housed with its main body side located within the branch space 7cc and its drive shaft 4a side located within the central space 7ca. The power transmission unit 6 is housed with its connection portion 6b with the cam 5 located within the central space 7ca and extending in a direction substantially perpendicular to the drive shaft 4a, with its connection portion 6a with the batting rod 3 located within the branch space 7cb. A support member such as a collar 7d that supports the batter 3 so that it can move back and forth in the length direction is provided at the portion of the end wall 7ab of the branch space portion 7cb through which the batter 3 passes.

[0029] The number and shape of the branch spaces in the housing 7 can be changed by changing the angle, number and arrangement of the bends of the V-shaped curved wall portion 7aa in plan view, and by changing the shape of the housing 7.

[0030] - Angle of bending of V-shaped curved wall in plan view In the illustrated example, the bending angle of the curved wall portion 7aa is approximately 120 degrees. The reason for setting this bending angle to approximately 120 degrees is that the shape of the branch spaces 7cb to 7cd toward their distal ends can be made approximately rectangular in plan view. Note that this bending angle can be changed by changing the number of curved wall portions 7aa and the shape of the housing 7.

[0031] - Shape of the part where the bat penetrates While the curved wall portions 7aa and end walls 7ab have been described as having substantially the same shape, in the illustrated example, some of the shapes are slightly different. That is, the end wall 7ab through which the striker 3 passes and the curved wall portion 7aa connected to the end wall 7ab are slightly different in shape from the others. Specifically, the end wall 7ab through which the striker 3 passes is slightly bent so that the portion of the wall that passes through it is oriented substantially perpendicular to the length of the striker 3 (the direction of movement of the striker 3). Furthermore, the curved wall portion 7aa connected to the end wall 7ab is slightly shorter than the portion of the wall that passes through it because the end wall 7ab is bent inward. The reason the portion of the end wall 7ab through which the striker 3 passes is oriented substantially perpendicular to the length of the striker 3 is that the amplitude direction of the vibration of the gong 2 is perpendicular to the striking position, making it easier for the striking force to propagate as vibration.

[0032] <Gong striking position> Vibration antinode, angle distance from slit The gong 2 can have vibration antinodes located at angular intervals of 35 to 55 degrees circumferentially from the slit 2e in the circumferential side portion 2c (angular intervals from the circumferential midpoint of the slit; the same applies below). The striking rod 3 can be positioned to strike positions within this angular interval. In the illustrated example, the gong 2 has vibration antinodes located at angular intervals θ of approximately 45 degrees circumferentially from the slit 2e in the circumferential side portion 2c, and the striking rod 3 is positioned to strike positions at this angular interval θ of approximately 45 degrees.

[0033] -Improved sound pressure (due to the gong striking position) In the alarm bell 1 of this invention, the vibration efficiency of the gong 2 can be improved by striking positions within an angular interval of 35 to 55 degrees circumferentially from the slit 2e in the circumferential side 2c, where the antinode of the vibration of the gong 2 is located. Furthermore, by striking positions within this angular interval, for example, at angular intervals of approximately 45 degrees as in the illustrated example, the sound pressure of the gong 2 can be increased, as shown in the results of a sound measurement experiment described below.

[0034] - Sound pressure measurement experiment (compared to hitting positions spaced approximately 90 degrees apart) The inventors conducted an experiment to measure the sound pressure of the gong sound produced by striking the gong with the striker at a position on the gong's vibration antinode, approximately 45 degrees apart from the slit on the periphery of the gong, as in the present invention, and at a position approximately 90 degrees apart in the same direction.The results of the experiment showed that the sound pressure of the gong struck at a position approximately 45 degrees apart from the slit was higher than that of the gong struck at a position approximately 90 degrees apart from the slit.This result is believed to be due to the fact that striking a position closer to the slit, which is on the gong's vibration antinode, improves the vibration efficiency of the gong when struck, as mentioned above.

[0035] The inventors also conducted sound pressure measurements at a position approximately 8 degrees circumferentially away from the slit (a position approximately 53 degrees from the slit) from a position approximately 45 degrees from the slit (a position corresponding to the antinode of vibration). The sound pressure obtained was comparable to that obtained when striking a position approximately 45 degrees from the slit. This suggests that, while the most desirable striking position for the gong 2 with the striker 3 is a position corresponding to the antinode of the gong 2's vibration, a similar improvement in sound pressure can be expected even if the striking position is shifted from this position, as long as the shift is within a circumferential range of approximately ±10 degrees. Of course, a similar improvement in sound pressure can be expected as long as the shift is within a circumferential range of approximately ±5 degrees. For example, if the antinode of the vibration of the gong 2 is located approximately 45 degrees circumferentially from the slit 2e as in the illustrated example, even if the striking position is shifted from that position, it can be expected that the same level of improvement in sound pressure will be achieved as long as the striking position is within an angular range of 35 to 55 degrees circumferentially from the slit 2e. Of course, it can also be expected that the same level of improvement in sound pressure will be achieved as long as the striking position is within an angular range of 40 to 50 degrees circumferentially from the slit 2e.

[0036] <Example of housing shape change> The shape of the housing 7 can be modified as appropriate as long as it has portions corresponding to the plurality of V-shaped curved wall portions 7aa in plan view. For example, the bending angles of the V-shaped curved wall portions 7aa in plan view may be set to approximately right angles, the number of the V-shaped curved wall portions 7aa may be set to four, and the housing 7 may have a cross shape in plan view.

[0037] <Other parts that contribute to improving sound pressure> - Thinning of the central area of ​​the base of the gong In the illustrated example, the gong 2 has a continuous annular groove 2bb around a fixed portion 2ba located on the inner surface of the bottom portion 2b, approximately in the center in a plan view. The groove 2bb reduces the thickness of the bottom portion 2b near the center in a plan view. When the sound pressure of the gong 2 was measured with and without the thinning of the thickness, the sound pressure was higher with the thinned portion than without the thinned portion. This suggests that the sound pressure of the gong 2 can be increased by providing the groove 2bb and thinning the bottom portion 2b of the gong 2 near the center in a plan view.

[0038] <Benefits of improved sound pressure> -Miniaturization of the gong As described above, the alarm bell 1 of this invention can increase the sound pressure of the bell sound. This allows the gong 2 to be made smaller, but still meet the sound pressure standards required by the Fire Service Act when used as an emergency bell.

[0039] - Sound pressure measurement experiment (sound pressure when a gong is made smaller) The outer diameter of the gong in a conventional emergency bell is typically 150 mm. The inventors prepared a prototype alarm bell with a gong diameter of 130 mm, but with a similar configuration to alarm bell 1 of the present invention, and conducted experiments to measure the sound pressure of the bell sound. The results showed that the prototype achieved a sound pressure of 90 dB or more, the standard required by the Fire Service Act. This result is believed to be due in particular to the fact that the prototype's housing is Y-shaped in plan view, as in housing 7 of the illustrated example, and that the striking position of the mallet is located at the antinode of the gong's vibration, approximately 45 degrees apart from the slit on the periphery of the gong, as in the striking position of mallet 3 of the illustrated example.

[0040] In other words, in the alarm bell 1 of this invention, as shown in the example, the housing 7 has a Y-shape when viewed from above, and the position at which the striker 3 strikes the gong 2 is the antinode of the vibration of the gong 2, and is located at an angular interval of approximately 45 degrees circumferentially from the slit 2e in the peripheral side part 2c of the gong 2. Therefore, even if the outer diameter of the gong 2 is reduced to, for example, 130 mm to make it compact, it will still be able to meet the sound pressure standards required by the Fire Service Act when used as an emergency bell.

[0041] In addition, in Figures 1 to 3, as well as in Figures 4 to 6, which will be referred to later in the explanation of the case where the alarm bell 1 is made to be a rainproof type, the dimensional ratios of each part are shown assuming that the outer diameter of the gong 2 is 130 mm.

[0042] <Advantages of a smaller gong> -Reduced manufacturing costs As described above, in the alarm bell 1 of the present invention, the gong 2 can be made smaller, thereby reducing manufacturing costs.

[0043] -Improved workability (when used as a rainproof type) 4 and 5 show how the weatherproof alarm bell 1 is mounted in a wall W with a flush-mounted switch box 50 embedded in the wall W. The switch box 50 is embedded in the wall W together with a front painted cover 40, and a weatherproof mounting bracket 30 (a three-layer structure with waterproof packing on the front and back of the bracket) is exposed on the surface of the wall W and attached to the painted cover 40 with screws. The weatherproof alarm bell 1 has a weatherproof mounting plate 7j (which has an internal space and may be called a case or box) on the back side of the housing 7 in place of the back cover 7g (or may have this in addition to the back cover 7g and insulating sheet 7h). When the switch box 50 is mounted in the wall W, the mounting plate 7j is fixed to the mounting bracket 30 on the switch box 50 side with screws 7jb (an example of a fixing member).

[0044] The mounting bracket 30 on the switch box 50 side is a general-purpose part, and the screw holes 30a into which the alarm bell 1 is screwed are located at positions determined by standards. Screw holes 7ja (an example of a through-hole for a fixing member) on the mounting plate 7j on the alarm bell 1 side are located at positions corresponding to the screw holes 30a on the mounting bracket 30 on the switch box 50 side. In the illustrated example, the screw holes 7ja are located at each corner (an example of an edge) of the mounting plate 7j. If the gong 2 is a large one with an outer diameter of 150 mm, as in the conventional gong 2, the screw holes 7ja would be hidden behind the gong 2 in a plan view. In this case, when the mounting plate 7j is attached to the gong 2 together with the housing 7, it is not possible to insert the screws 7jb into the screw holes 7ja and screw them into the screw holes 30a on the mounting bracket 30 on the switch box 50 side. Therefore, once the gong 2 and housing 7 are assembled, they must be removed, the mounting plate 7j must be screwed to the mounting bracket 30 on the switch box, and then the gong 2 and housing 7 must be reassembled. In contrast, if the gong 2 is made small, with an outer diameter of, say, 130 mm, as in the present invention, even when the housing 7 is attached to the gong 2, the screw holes 7ja in the mounting plate 7j are located on the outside of the gong 2 and are exposed to the outside, so that the screws 7jb can be used to screw the gong 2 into the mounting bracket 30 on the switch box 50.

[0045] That is, in the alarm bell 1 of the present invention, the gong 2 can be made smaller, which can improve the ease of installation when it is installed as a weatherproof type.

[0046] <Example of configuration changes> In the alarm bell 1 of the present invention, the configuration can be changed, for example, as follows.

[0047] For example, the outer diameter of the gong 2 is not limited to 130 mm and may be larger or smaller. Even if the diameter is increased or decreased, the sound pressure of the gong sound can be improved by configuring the shape of the housing 7 and the striking position of the mallet 3 as described above. [Explanation of symbols]

[0048] 1: Alarm bell 2: Gong 2a: Space 2b: Bottom 2ba: Fixed part 2bb: Groove 2c: Side 2d: Rim 2e: Slit 3: batting rod 3a: striking part 3b: connecting part 4: motor 4a: driving shaft 5: Cam 6: Power transmission part 6a: Connection part (batting rod side) 6b: Connection part (cam side) 7: Housing 7a: Peripheral wall 7aa: Curved wall part 7ab: End wall 7b: Bottom wall 7ba: Convex part 7bb: Screw 7c: Inside 7ca: Central space 7cb~7cd: Branch space 7d: Color 7f: Opening 7g: Back cover 7h: Insulation sheet 7i: Hook 7j: Mounting plate 7ja: Screw hole 7jb:Screw 30:Mounting bracket 40:Paint margin cover 50: Switch box W: Wall

Claims

1. An alarm bell comprising: a gong that is circular in plan view and produces a bell sound when struck; a striking rod that strikes the gong; and a motor that drives the striking rod, The gong has only two slits formed in the rim of its peripheral side at equal angular intervals in the circumferential direction, and has antinodes of vibration of the gong at angular intervals of 35 to 55 degrees from one of the slits in the circumferential direction, The alarm bell is characterized in that the striking rod strikes a position within the range of the angular interval.

2. 2. The alarm bell according to claim 1, wherein the striking rod strikes a position at an angular interval of approximately 45 degrees in the circumferential direction from one of the slits, where the antinode of vibration of the gong is located.

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