Electrical generator or motor structure – Non-dynamoelectric – Charge accumulating
Reexamination Certificate
2002-04-04
2004-06-22
Budd, Mark (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Charge accumulating
Reexamination Certificate
active
06753640
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a piezoelectric driven type vibratory feeder.
2. Description of the Related Art
As a first example of a piezoelectric driven type vibratory feeder, a device, such as that illustrated in
FIG. 15
, is disclosed in Japanese Patent No. 2762211. A transporting member
5
(term used in the specification, and will be used below) is supported by transporting member supporting members
8
, which are a pair of front and back vertical spring steel members. The lower end portions of the transporting member supporting members
8
are secured to a base
3
. The heights of the front and back portions of the base
3
are different. In other words, the base
3
has a trapezoidal shape. Therefore, the spring operating lengths of the transporting member supporting members
8
differ at the front and back sides of the base
3
. A pair of front and back vibration members
9
are secured to the bottom surface of the transporting member
5
, and comprise corresponding piezoelectric devices
1
bonded to both surfaces of corresponding elastic plates
2
. Accordingly, the piezoelectric driven type vibratory feeder has what is called a bimorph structure. Mass members
7
and
7
having different masses are mounted to the lower ends of the corresponding elastic plates
2
. Transportation parts
6
are to be transported on the transporting member
5
in the direction of an arrow. When an alternating voltage is applied to the piezoelectric devices
1
, the piezoelectric devices
1
bonded to both surfaces of their corresponding elastic plates
2
expand and contract. By the expansion and contraction of the piezoelectric devices
1
, the transporting member
5
vibrates in an oblique direction, so that the transportation parts
6
are, as conventionally known, transported in the direction of the arrow.
In such a piezoelectric driven type vibratory feeder, however, since the mass members
7
and
7
are secured to the lower ends of their corresponding elastic plates
2
, and the transporting member
5
is secured to the bases of the elastic plates
2
, rotational motion occurs around the secured points as indicated by the double-headed arrows. This causes rotational motion of the transporting member
5
, which may be very complicated. In addition, a common alternating voltage is applied. Therefore, since the masses of the mass members
7
and
7
are different, even if the spring constants of the elastic plates
2
are the same, the resonant frequencies of these two vibratory systems are different. Consequently, the amplitudes of the mass members
7
and
7
are different, and, with regard to their vibration displacements, the alternating voltages applied to the mass members
7
and
7
are out of phase. Thus, the transporting member
5
may vibrate in a more complicated manner, so that a smooth transportation operation may not be performed over the entire transporting member
5
.
FIG. 16
illustrates a second conventional example of a piezoelectric driven type vibratory feeder disclosed in Japanese Patent Examined Publication HEI02-50806 B2. By bolts b, ends of an obliquely provided pair of front and back plate springs
13
a
and
13
b
are secured, one at each end of a plate-spring-mounting block
12
secured to the bottom surface of a trough
11
. By corresponding plate-spring-mounting blocks
14
a
and
14
b
, the bottom end portions of the plate springs
13
a
and
13
b
are secured to the top ends of their corresponding piezoelectric-device-mounting plate springs
15
a
and
15
b
disposed below the plate springs
13
a
and
13
b
. The bottom end portions of the piezoelectric-device-mounting plate springs
15
a
and
15
b
are secured to a base
17
. Piezoelectric devices
16
a
and
16
a′
and piezoelectric devices
16
b
and
16
b′
are bonded to both surfaces of the plate springs
15
a
and
15
b
, respectively. Alternating voltages are applied to the piezoelectric devices
16
a
and
16
a′
and the piezoelectric devices
16
b
and
16
b′
, so that the plate springs
15
a
and
15
b
bend. The trough
11
amplifies vibration by the upper plate springs
13
a
and
13
b
. Even in this conventional example, a vibration-proof structure is not provided. Therefore, from the bottom end portions of the lower plate springs
15
a
and
15
b
, a reaction force resulting from the vibration of the tough
11
or a bending reaction force of the plate springs
15
a
and
15
b
is directly transmitted to the base
17
, so that, not only are other similar vibration mechanisms mounted to a common installation base Q adversely affected, but also noise is produced by a reaction force that is transmitted through the floor. In order to overcome these problems, a vibration-proof structure, such as that shown in
FIG. 17
, can be provided. In
FIG. 17
, corresponding parts to those shown in
FIG. 16
are given the same reference numerals, and are not described in detail below. In the piezoelectric driven type vibratory feeder having the vibration-proof structure, a vibration-proof block
18
is mounted below the base
17
, and is joined to an installation base
19
by a pair of front and back vibration-proof springs
20
a
and
20
b
having small spring constants. By this structure, the vibration reaction force transmitted to the base
17
is virtually not transmitted to the installation base
19
due to deflection of the vibration-proof springs
20
a
and
20
b
. In such a structure, however, the height of the entire piezoelectric driven type vibratory feeder becomes large. Therefore, a problem concerning the relationship with other devices disposed near the piezoelectric driven type vibratory feeder for proper arrangement therewith and a problem of a lack of stability of the piezoelectric driven type vibratory feeder arise.
SUMMARY OF THE INVENTION
In view of the above-described problems, it is an object of the present invention to provide a piezoelectric driven type vibratory feeder whose working mass member vibrates stably over the entire area of the working mass member and which can prevent a reaction force from being transmitted to an installation base or a base without increasing the height of the entire piezoelectric driven type vibratory feeder.
To this end, according to a basic form of the present invention, there is provided a piezoelectric driven type vibratory feeder comprising a base; a plurality of first plate springs, with a lower end portion of each of the plurality of first plate springs being secured to the base; a working mass member connected to an upper end portion of each of the plurality of first plate springs, and supported at the base so that the working mass member can vibrate; a plurality of second plate springs, with an upper end portion of each of the plurality of second plate springs being secured to the working mass member; a single opposing mass member, with a lower end portion of each of the plurality of second plate springs being connected to the single opposing mass member; a piezoelectric device bonded to at least one surface of each of the plurality of second plate springs; and alternating voltage applying means for applying alternating voltage to each piezoelectric device. In the piezoelectric driven type vibratory feeder, by applying the alternating voltage to each piezoelectric device, each of the plurality of second plate springs undergoes bending vibration, causing the working mass member to vibrate by the bending vibration, so that an object is transported on the working mass member.
By virtue of the above-described structure, it is possible to prevent a reaction force from being transmitted to the base without increasing the height of the entire vibratory feeder. In addition, it is possible to smoothly transport an object to be transported by uniformly and stably vibrating the working mass member without producing rotational motion that results in perturbation.
When the structure of the basic form is used, a total spring constant of the first plate springs may be suff
Fujii Takayoshi
Kato Kazumichi
Kimura Tetsuyuki
Muragishi Yasushi
Saito Nobuhiro
Budd Mark
Shinko Electric Co. Ltd.
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