Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to an electric bell of the type
which is driven by a motor and adapted for use in a fire
bell, an alarm bell or the like, and more particularly to
a gong striking mechanism driven by a motor to strike a
gong.
Prior art electric bells have had the drawback of
having a rotating pivot plate connected to a motor shaft.
The pivot plate has a counter-weight at one end and a
striking hammer at the other. The pivot plate cannot be
perfectly balanced and consequently fluctuates during the
striking of the gong. As a result, the motor shaft either
bends due to the large torque to which it is subjected or
the pivot plate falls off the shaft because it cannot
properly be secured thereto.
One prior art configuration attempts to overcome this
situation, however t it requires complex and expensive
parts.
Accordingly, it is an object of this invention to
provide a novel gong striking mechanism in which the
above-described drawbacks accompanying a conventional
electric bell are overcome. Another object of the
invention is to provide a mechanism in which reliable and
simple parts may be employed to eliminate difficulties in
manufacturing and in adjusting bell sound volumeO
In accordance with one aspect o~ the invention there
is provided a gong striking mechanism comprising a driving
electric motor, including a motor shaft, mounted on a
frame within a gong; conversion means rotatably connected
to the motor shaft for conve~ting continuous rotational
motion of the motor shaft to reciprocal gong striking
motion, said conversion means comprising a cylindrical
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end cam rotatably attached to the motor shaft and a
reciprocating rod, one end of which abuts said cylindrical
end cam and the other end of which forms a hammer for
striking said gong resilient means adapted to absorb
impact force during the gong striking motion disposed
between said motor and said hammer, said resilient means
comprising a spring having one end thereof fixed to said
reciprocal rod.
BRIEF DESCRIPTION OF THE DRAWINGS
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In drawings which illustrate embodiments of the
invention:
FIGS. 1 and 2 are sectional side and bottom views,
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respectively, illustrating examples of a conventional
motor driven type bell;
FIGS. 3 and 4 are sectional side and bottom views,
respectively,.of a first embodiment of the invention;
FIGS. 5 and 6 are sectional side and bottom views,
respectively, of a second embodiment of the invention;
FIGS. 7 and 8 are sectional side and bottom views,
respectively, of a third embodiment of the invention;
FIGS. 9 and 10 are sectional side and bottom views,
respectivelyr of a fourth embodiment of this invention;
FIGS. 11 and 12 are each sectional side views of a
fifth embodiment of this invention; and
FIGS. 13, 14 and 15 are two sectional side views and a
plan view, respectively, of a hammer and a collar between
which a resilient means are arranged.
DETAILED DESCRIPTION OF THE INVENTION
In a conventional electric bell as shown in FIG. 1, a
pivoting plate 2 is rotatably fixed to a motor shaft 1. A
counter-weight 3 and a striking hammer 4 are attached at
opposite ends of plate 2. The striking hammer 4 is
arranged in a slot 5 to move foward and backward against a
gong 6 during the operation of a motor 7. The location of
the striking hammer 4 varies each time it strikes the gong
6 so that the weight balance between the two ends of the
pivoting plate 2, with respect to the rotary shaft 1,
cannot attain an appropriate balance and fluctuates during
the hammer striking motion.
Moreover, when the motor 7 st.arts to rotate and the
striking hammer ~ strikes the gong 6`, the rel.atively long
plate 2 having counter-weight 3 and the striking hammer 4
at its ends either bends the motor shaft 1 due to the
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large torque imparted thereon, or gradually falls off the
shaft 1 since there is no provision for fixing the plate 2
to the shaft 1. The latter case occurs when the shaft is
relatively small in diameter and it is not possible to
insert a pin or the like to fix the shaft 1 and the plate
2. Therefore, the bell of the type described does not
have a smooth rotation of the motor 7. Further, the shaft
1 is subjected to a bending force which causes damage
thereto
In order to overcome these disadvantages, a bell as
shown in FIG. 2 has been proposed employing a cam 8
fixedly attached to an axle 9 of a motor 10. A crank rod
11 engages the cam 8 to convert the rotational motion of
the motor 10 to a reciprocal motion. This causes a spring
plate 12 to reciprocate to strike a gong 13 with a hammer
14 which is attached to the plate 12. The spring plate 12
is fixed at one end to a supporting plate 15 and is
connected at the other end to the crank rod 11.
In this bell, however, there exists some problems such
as a plurality of assembly processes to be accomplished,
high cost, and difficulty in adjustment to obtain an
optimum sound volume.
A first embodiment of the invention is shown in FIGS.
3 and 4 having a gong 30. The gong 30 is made of iron in
the form of a cup or the like.
A mounting plate 31 fixed to the central portion of
the inner wall of the gong 30 by an appropriate means,
such as a bolt or nut, supports a front wall 32, an
intermediate wall 33, and a rear wall 34. Each wall
extends downwardly from the mounting plate 31. These
three walls 32, 33 and 34 may be made integrally from a
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single steel sheet by bending it suitably to accommodate a
bell striking mechanism. A motor 35 is fixedly installed
on the rear wall 34. A motor shaft is rotatably inserted
through an opening formed in the center of the wall 34. A
cylindrical end cam 36 is rotatably fixed to the sha~t of
the motor 35. The end surface of the cam 36 engages with
a cylindrical cam follower 37 which rotates and
reciprocates through a hole formed in the intermediate
wall 33. A groove is formed on the surface of the cam
follower in axial alignment therewith. The groove
incorporates an elongated pin 3~ adapted to fit in a
recess formed in the intermediate wall 33 so that the cam
follower 37 is constrained in movement to an opera-ting
range. At the opposite side to the end surface of the cam
follower 37 which engages the end cam 36, there is a rod
portion having a smaller diameter and a hammer 39 at its
extremity. The hammer 39 is disposed in proximity with
the inner surface of the gong 30. A spring 40 is arranged
between the inside of the front wall 32 and the end
portion of the cam follower 37, to absorb the impact force
exerted on the cam follower 37.
A second embodiment of the invention will be described
with reference to FIGS. 5 and 6 and has a gong 30 of the
same type as described in the first embodiment. It should
be understood that like parts are indicated by like
reference numerals in FIGS. 3, 4, 5 and 6. The difference
between the first and second embodiment lies in that the
latter is mainly composed of a cylindrical cam 36 and a
cam follower 37, having at a predetermined position, a
protrusion 41 around the periphery thereof. The cam
follower 37 has at one end a hammer 39 and abuts directly
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with the end surface of the cam 36 at the other end.
Thus, the elements making up the cam follower body in the
first embodiment are eliminated. The only difference in
operation resides in that the stroke of the hammer 39 is
shorter compared with the first embodiment.
A third embodiment of the invention is shown in FIGS.
7 and 8 in which a supporting plate 70 is fixedly attached
to the gong 71 at a central portion thereof. The plate
supports a motor 72 and bearings 73. One end of a
flexible wire or tube 74 is connected to the shaft of
motor 72. The other end is rotatably supported by the two
bearings 73.
An eccentric cam 75 is fixed to the flexible wire 74
between the two bearings 73. The cam 75 is located
adjacent a pro~rusion 76 formed on the inner surface of
the gong wall.
FIGS. 9 and 10 illustrate a fourth embodiment of the
invention having a gong 90. There is provided a motor 91,
a cam 92 fixed to the motor shaft, a spring plate 93
disposed to engage with the cam, and a hammer 94 fixed to
the spring plate. The plate 93 is fixed at one end to the
supporting plate 95 so that the hammer 94 faces a
protrusion 95 formed on the inner surface of the gong
wall. The hammer 94 strikes the protrusion 95.
FIGS. 11, 12, 13, 14 and 15 illustrate a fifth
embodiment of the invention having a gong 101. A
supporting plate 106 is fixedly connected to the gong
101~ The plate receives, at one end, a motor 105
connected to a shaft 104. A collar 103 is fixedly
attached to shaft 104 in such a manner that it is offset
from the center of the collar 103. A hammer 102 having a
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~cylindrical shape, surrounding collar 103 thereby strikes
a protrusion 107 once every rotation of the motor shaft.
The hammer maintains a predetermined distance and is
restrained around the collar 103 by a rim integrally made
at the top edge thereofO In the space between the collar
103 and the hammer 102, there is provided resilient means
which absorb, in part, shock resulting from a striking
motion of the hammer 102 against the protrusion 107. The
resilient means are exemplified in FIGS. 13, 14 and 15 in
such a manner that the hammer 102 and the collar 103 are
supported resiliently on each other by springs 108 which
are fixed at both ends to the grooves formed either in the
hammer 102 or the collar 103 (FIG. 13). The hammer 102
and the collar 103 can be resiliently associated with each
other by springs 109 which are fixed at one end thereof to
the groove formed in the collar 103 and which are free at
their other ends (FIG. 14). The hammer 102 and the collar
103 can be resiliently associated with each other by
employing a shock absorber such as a spring wire 110 or a
plate spring which is fixed around the collar surface by
an appropriate fixing means such as a bonding agent (FIG.
15).
Upon energization of the motor, its shaft rotates so
that the cylindrical cam 36, the flexible tube 74, the
eccentric cam 92 or the collar 102 rotatesO This ca~ses
the hammer 39, the eccentric cam 75, the hammer 94 or the
hammer 102 to move reciprocally, relative to the gong 30
or the protrusions 76, 95, 107 in order to generate bell
sounds. Each time the hammer 39~ the eccentric cam 75,
the hammer 94 or the hammer 102 strikes the gong 30 or the
protrusions 76, 95, 107, impact forces are exerted upon
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the hammer 39, the eccentric cam 75, the hammer 94 or the
hammer 102. Impact forces are absorbed in part in the
resilient means thereby to cause no damage to the motor
shaft by eliminating the possible bending force applied to
the shaft.
As is described above, it is a feature of the
invention to provide a bell striking mechanism in which
driving power for a hammer to strike a gong is supplied
from a motor by a converison means rotatably connected
directly or indirectly to the motor shaft. The conversion
means in one embodiment of the invention preferably
comprises a cylindrical end cam rotatably attached to the
motor shaft, and cylindrical cam follower on one end of
which the end surface of the cam abuts and to the other
end of which a reciprocal rod having at the end portion
thereof a hammer to strike the gong is fixedly connected.
It is another feature of the invention to provide a bell
striking mechanism in which a resilient means is disposed
between the motor and a hammer so that impact forces
imparted on the hammer during a bell striking motion are
absorbed to some extent, thereby causing no damage to the
motor shaft.
