JP7756221B2 - Alarm bell - Google Patents

Description

This invention relates to an alarm bell that sounds an alarm by striking a gong.

An alarm bell comprises a gong that produces a bell sound when struck, a striker that strikes the gong, a motor that drives the striker, and a housing that houses the motor. In the event of an emergency such as a fire, the gong sounds, producing a bell sound and issuing an alarm (see, for example, Patent Document 1).

Main uses include the local sounding devices in automatic fire alarm systems and the emergency bells in the sounding devices of emergency alarm systems (hereinafter simply referred to as "emergency bells").

Japanese Patent Application Laid-Open No. 2000-235394

When used as emergency bells, this type of alarm bell is often installed in such a way that multiple units ring simultaneously (either in separate rings or all at once). For this reason, it is preferable for the current consumption (drive current) of each alarm bell's motor to be small.

In consideration of the above circumstances, this invention aims to provide an alarm bell that can reduce the motor's current consumption.

This invention relates to an alarm bell that includes a striker, a gong struck by the striker, and a power transmission member that transmits power from a motor to the striker via a cam, and that sounds the gong when struck by the striker, sounding an alarm. The power transmission member is connected at its base end to the cam and at its tip end to the striker, and the cam has a cam surface portion that functions as a cam surface and is wound around the connecting portion at the base end of the power transmission member, and a flange portion whose inner wall surface is provided with an inclined surface that slopes toward the cam surface portion.

In this invention, the cam surface portion can be configured so that one end in the longitudinal direction rotates with a larger radius of rotation than the other end.

Furthermore, in this invention, the cam surface portion may have a larger axial width at one end than at the other end.

In this invention, the inner wall surface of the cam's flange is provided with an inclined surface that slopes toward the cam surface. Therefore, even if the contact area with the connecting part of the power transmission member comes into contact with the inclined surface when the cam rotates, the contact occurs at a portion closer to the cam surface rather than at the outer periphery of the inclined surface, thereby reducing the friction torque generated by the contact. This reduces the load on the motor and reduces the motor's current consumption.

Therefore, this invention provides an alarm bell that can reduce the motor's current consumption.

This shows an example of an embodiment of the alarm bell of the present invention, and is a rear view showing the striking mechanism part, such as the striking rod and motor, which are provided on the back side of the gong, with the back cover of the housing open. 2A is an enlarged side view of the example of the striking rod of the alarm bell of the same embodiment as shown in FIG. 1, FIG. 2B is an enlarged side view of another example, and FIG. 2C is an enlarged side view of yet another example. 4A is a perspective view of the cam of the alarm bell in a state where a power transmission member is connected, and FIG. 4B is a bottom view thereof. (a) is a front view (one side of the flange), (b) is a left side view, (c) is a right side view, (d) is a top view, and (e) is a cross-sectional view along line A-A in (a) of the cam alone of the alarm bell.

An example of an embodiment of the alarm bell of this invention will be described as alarm bell 1 with reference to Figures 1 to 4. Note that alarm bell 1 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.

[Basic configuration]
As shown in Figure 1, the alarm bell 1 comprises a gong 2, a striking rod 3 that strikes the gong 2, a motor 4 that drives the striking rod 3, and a power transmission member 6 that transmits the power of the motor 4 to the striking rod 3 via a cam 5. In the event of an emergency such as a fire, the striking rod 3 causes the gong 2 to ring and sound an alarm. The striking mechanism, including the striking rod 3 and motor 4, is located on the inside surface of the gong 2.

[Battery stick]
Specifically, the striking rod 3 moves back and forth along its length using the power of the motor 4 transmitted via a cam 5 and a power transmission member, and when it moves forward, it strikes the gong 2 with the spherical crown-shaped striking part 3a at the tip.

Slit As shown in FIGS. 1 and 2(a), the striking rod 3 is provided with a slit 3c at a position close to the striking part 3a that strikes the gong 2.

In the alarm bell 1, the provision of this slit 3c increases the repulsive force of the striking rod 3 when it strikes the gong 2. This reduces the load on the motor 4 when the striking rod 3 is pulled back, thereby reducing the current consumption of the motor 4.

Specific example of slit Specifically, in the illustrated example, the slit 3c is recessed into the side of the batter 3, and forms a long, narrow groove in the transverse direction of the batter 3. Furthermore, the depth of the groove exceeds the center line of the batter 3 in the longitudinal direction.

Modifications to the Slits The shape of the slit 3c can be modified as needed, as long as it increases the repulsive force during impact. For example, while the slit 3c has one groove, multiple grooves may be used. Figure 2(b) shows an example of multiple grooves. In the figure, slits 3c', 3c' each have two grooves. Like slit 3c, both grooves are recessed into the side of the batting rod 3 and extend in the transverse direction of the batting rod 3. However, they are arranged in two rows, front and rear, and open in opposite directions. When multiple grooves are arranged in rows, the openings of the grooves may alternately open in opposite directions, as described above, or they may open in the same direction.

Holes As a means for increasing the repulsive force of the batting rod 3 during a hit, holes may be used instead of or in addition to grooves such as the slits 3c and 3c'. Figure 2(c) shows an example of a hole being used instead of a groove. In this figure, hole 3c'' is shown as a through-hole that penetrates the side of the batting rod 3. There is only one hole, and its shape is rectangular (including rounded corners). The number and shape of hole 3c'' can be changed as appropriate. For example, there may be multiple holes, or the hole may be another polygonal shape (including rounded corners), circular, or elliptical. Furthermore, instead of a through-hole, a recessed hole may be formed as a non-through hole.

[cam]
1, the cam 5 is fixed to the drive shaft 4a of the motor 4 and rotates together with the drive shaft 4a. The cam 5 is connected to a base end connection portion 6a of a power transmission member 6, whose tip end connection portion 6b is connected to the striking rod 3, and the power of the rotational motion of the motor 4 is transmitted to the striking rod 3 as reciprocating power via the cam 5 and the power transmission member 6. This causes the striking rod 3 to reciprocate back and forth in the length direction.

Specifically, as shown in Figures 3 and 4, the cam 5 has a cam surface portion 5a around which the connecting portion 6a of the power transmission member 6 is wound and connected, functioning as a cam surface, and flange portions 5b, 5b provided on both axial sides of the cam surface portion 5a.

In the illustrated example, the power transmission member 6 is made of a linear member and has a bent portion along the way to give it spring properties (see Figures 1 and 3).

Inclined Surfaces The flange portions 5b, 5b of the cam 5 are provided on their inner wall surfaces with inclined surfaces 5c, 5c that are inclined toward the cam surface portion 5a.

In the alarm bell 1, the inclined surfaces 5c, 5c are provided. Even if the contact portion between the cam 5 and the connecting portion 6a of the power transmission member 6 comes into contact with the inclined surface as the cam 5 rotates, the contact occurs at a portion close to the cam surface 5a, rather than at the outer periphery of the inclined surface, thereby reducing the friction torque generated by the contact. This reduces the load on the motor 4 and the current consumption of the motor 4.

It is preferable that the inclined surfaces 5c, 5c are provided on both sides of the flange portions 5b, 5b, but they may be provided on only one side.

In the illustrated example, the cam 5 is arranged so that the cam surface 5a rotates with a larger radius of rotation at one end 5aa in the longitudinal direction than at the other end 5ab (see FIGS. 3(a) and 4(d)). This provides power for reciprocating motion, but because the connecting portion 6a is normally always in contact with the end 5ab, the rotational torque load can be reduced. This also reduces the load on the motor 4, thereby reducing the current consumption of the motor 4.

Furthermore, in the illustrated example, the cam 5 has a larger axial width at one end 5aa than at the other end 5ab (see Figure 4(d)). As a result, the power transmission part 6 only comes into contact with the 5ab side, which is normally the smaller diameter side, thereby reducing the current consumption of the motor 4.

[Configuration change example]
In the alarm bell 1, for example, the configuration can be changed as follows.

The depth of the slits 3c and 3c' may be shallower. However, as mentioned above, in order to increase the repulsive force of the batter 3 when hitting, it is advantageous to make the depth extend beyond the center line of the batter 3 in the longitudinal direction.

The angle of inclination of the inclined surfaces 5c, 5c can be changed as appropriate, and may be steeper or gentler than that shown in the figure.

The same effect can also be achieved by making the following changes:
The inclination of the cam 5 may be an arcuate inclination instead of a linear inclination.
The central axis of the cam 5 may be eccentric and not coincident with the center of gravity of the cam 5. The shape of the cam 5 may be an ellipse instead of a circle, a rounded rectangle, or a rounded triangle.
The thickness of the flange portion 5b of the cam 5 may vary depending on the position of the cam. For example, in order to even out the rotation balance of the cam 5, the end 5aa side may be made thinner and the end 5ab side may be made thicker.
The cam surface portion 5a may have a shape having multiple end portions 5aa extending from the center toward the distal end. In this case, the cross-sectional shape of the cam surface portion 5a may be a rounded triangle or a rounded rectangle. For example, if the cross-sectional shape is a rounded triangle, the power transmission member 6 can reciprocate three times during one rotation of the cam 5.

1: Alarm bell 2: Gong 3: Mallet 3a: Striking part 3c, 3c': Slit 3c'': Hole 4: Motor 4a: Drive shaft 5: Cam 5a: Cam surface part 5aa, 5ab: End part 5b: Flange part 5c: Inclined surface 6: Power transmission part 6a, 6b: Connection part

Claims (3)

An alarm bell comprising: a hammer; a gong struck by the hammer; and a power transmission member that transmits power of a motor to the hammer via a cam, wherein the gong sounds when struck by the hammer to issue an alarm,
a base end side of the power transmission member is connected to the cam, and a tip end side of the power transmission member is connected to the striking rod;
An alarm bell characterized in that the cam has a cam surface portion around which the connection portion on the base end side of the power transmission member is wound and which functions as a cam surface, and a flange portion whose inner wall surface has an inclined surface that slopes toward the cam surface portion. An alarm bell as described in claim 1, characterized in that the cam surface portion rotates with a larger radius of rotation at one end in the longitudinal direction than at the other end. 3. The alarm bell according to claim 2, wherein the cam surface portion has a larger axial width at the one end side than at the other end side.