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BACKGROUND OF THE INVENTION
The present invention relates to a diaphragm-type air pump, and more
particularly to a diaphragm-type air pump capable of fully utilizing
magnetomotive force of an electromagnet, for example, reducing leakage
magnetic flux or effectively utilizing gap magnetic flux between main
poles and side poles, whereby remarkably improving pump capacity, and
lightening and miniaturizing pumps.
Hithereto, diaphragm-type air pumps have been used mainly in supplying
oxygen to water tanks for pisciculture or domestic purifying chamber, or
in sampling inspection gas for the monitoring of environmental pollution.
An electromagnet consisting of a core 30 comprising an E-shaped laminated
iron plate shown in FIG. 15 and coils (not shown) wound around the core 30
has been used in the above-mentioned conventional diaphragm-type air pump.
In FIG. 15, numerals 31 and 32 are a main pole and a side pole,
respectively.
When increasing the number of turns of coils to increase magnetic flux and
power of a pump in the electromagnet having a structure as described
above, there is a restriction on the size of a "vacant space" for coils
(refer to a in FIG. 15) so that the number of turns of coils is limited.
Therefore, it has been proposed to increase the size of a vacant space for
coils, or to increase the depth of the electromagnet (refer to b in FIG.
15) In either case, however, there are drawbacks as stated below so that
the pump capacity cannot be improved That is, when increasing the size of
a vacant space for coils, the increase of gap magnetic flux or passing
magnetic flux is limited because of the increase of a gap or distance
between the main pole and side pole. Further, the width of a permanent
magnet overlapping the main pole and side pole is enlarged and accordingly
the weight of the magnet is increased, so that the proper resonant
frequency of a vibration system is lowered. As a result the pump capacity
is lowered contrary to expectations. On the other hand, when increasing
the width of the electromagnet, leakage magnetic flux (.phi..sub.1) is
increased (refer to FIG. 16) due to the increase of permeance coefficient.
Moreover, effective magnetic flux (.phi..sub.2) is not equally increased.
As a result the pump capacity cannot be improved as is expected, since the
magnetic flux is not efficiently utilized
It is an object of the present invention to solve the above-mentioned
drawbacks and to provide a diaphragm-type air pump capable of effectively
utilizing magnetomotive force of the electromagnet, whereby remarkably
improving pump capacity, and lightening and miniaturizing pumps.
SUMMARY OF THE INVENTION
The present invention consists of three embodiments having a common object
of improving pump capacity.
In accordance with the first embodiment, there is provided a diaphragm-type
air pump wherein a diaphragm connected to a rod having permanent magnets
is driven by electromagnetic vibration of the rod caused by magnetic
interaction between an electromagnet and the permanent magnets,
characterized in that the electromagnet has a large distance between a
main pole and a side pole thereof, and tips of the main pole and the side
pole approach to each other so as to increase gap magnetic flux between
the main pole and the side pole and enable the use of permanent magnets
having smaller width than the distance between the main pole and side
pole, by bending or protruding a top of at least one of the main pole and
the side pole toward a tip of the other pole, or by fixing a previously
prepared tip portion to at least one of the main pole and the side pole in
such a manner that tips of both poles approach to each other.
According to the diaphragm-type air pump of the first embodiment, a
distance between a main pole and a side pole is enlarged so that the
permeance coefficient of a core of an electromagnet becomes small and
leakage magnetic flux is reduced Further, effective magnetic flux is
increased since at least one of the main pole and side pole is bent or
protrude in such a manner that both tips of the main pole and side pole
approach to each other. Still further, the width of a permanent magnet
extending over the main pole and side pole can be shortened, so that the
permanent magnet can be extended in its longitudinal direction according
to the decreased or lessened portion of the permanent magnet. Accordingly,
the magnetic attracting surface between the electromagnet and permanent
magnet is increased. By the effective utilization of magnetic flux,
magnetic interaction between the electromagnet and permanent magnet is
strengthened whereby the improvement of pump capacity is realized.
Next, the second embodiment provides a diaphragm-type air pump wherein a
diaphragm connected to a rod having permanent magnets is driven by
electromagnetic vibration of the rod caused by magnetic interaction
between an electromagnet and the permanent magnets, characterized in that
a main pole of the electromagnet has a small sectional area and a
supplementary magnetic path is formed at a tip of the main pole at the
side of the permanent magnets, so that a corresponding magnetic surface
between the main pole and the side pole is enlarged thereby increasing
permeance coefficient and gap magnetic flux, and that a magnetic
attracting portion between the main pole and the permanent magnets is
enlarged and interaction therebetween is strengthened.
According to a diaphragm-type air pump of the second embodiment, the number
of coils used can be reduced for obtaining the same magnetomotive force
since a core of the coils has small sectional area. Accordingly the
lightening and miniaturizing of the pump can be achieved. Further, since a
supplementary magnet path is attached to the main pole and the magnetic
attracting portion between the main pole and the permanent magnets is
enlarged, the attraction or repulsion between the permanent magnets and
the main pole including the supplementary magnetic path is strengthened
and the permeance coefficient is increased. In result, there can be
increased gap magnetic flux and mutual electromagnetic force.
The third embodiment provides a diaphragm-type air pump wherein a diaphragm
connected to a rod having permanent magnets is driven by electromagnetic
vibration of the rod caused by magnetic interaction between an
electromagnet and the permanent magnets, characterized in that a core of
the electromagnet comprises a plurality of main poles and a side pole.
According to a diaphragm-type air pump of the third embodiment, the amount
of copper wire used can be reduced to obtain the same magnetomotive force,
i.e. the same ampere-turn (IN), in comparison with a pump using one main
pole. Further, various kinds of pumps, from small-sized pumps to
large-sized pumps, can be manufactured using parts of the same
specification.
BRIEF EXPLANATION OF THE DRAWINGS
FIG. 1 is a sectional view partially including a plan view of an embodiment
of a diaphragm-type air pump of the present invention;
FIG. 2 is a schematic perspective view of an example of an electromagnet
core in a diaphragm-type air pump of the first embodiment;
FIG. 3 is a schematic perspective view of another example of an
electromagnet core;
FIG. 4 is a schematic perspective view of still another example of an
electromagnet core;
FIG. 5 is an explanatory view showing a state of magnetic flux of the core
shown in FIG. 2;
FIGS. 6a and 6b are a schematic explanatory plan view and a schematic
explanatory side view of magnetic attracting surface of a conventional air
pump, respectively;
FIGS. 7a and 7b are a schematic explanatory plan view and a schematic
explanatory side view of magnetic attracting surface of an air pump of the
first embodiment, respectively;
FIG. 8 is a schematic perspective view of an example of an electromagnet
core in a diaphragm-type air pump of the second embodiment;
FIG. 9 is a schematic perspective view of another example of an
electromagnet core in a diaphragm-type air pump of the second embodiment;
FIG. 10 is a schematic perspective view of a core obtained by
reconstructing the E-shaped core of the first invention shown in FIG. 4
according to an idea of the second embodiment;
FIGS. 11a and 11b are a schematic explanatory plan view and a schematic
explanatory side view of magnetic attracting surface of an air pump of the
present invention, respectively;
FIG. 11c is a schematic explanatory side view of magnetic attracting
surface of an air pump wherein permanent magnets are extended in its
longitudinal direction;
FIG. 12 is a schematic perspective view of an example of an electromagnet
core in a diaphragm-type air pump of the third embodiment;
FIG. 13 is a schematic perspective view of another example of an
electromagnet core in a diaphragm-type air pump of the third embodiment;
FIGS. 14a and 14b are schematic explanatory side views of magnetic
attracting surface of a middle-sized air pump and a large-sized air pump,
respectively;
FIG. 15 is a schematic perspective view of a conventional E-shaped
electromagnet core;
FIG. 16 is an explanatory view showing a state of magnetic flux of the core
shown in FIG. 15; and
FIG. 17 is a sectional view partially including a plan view of a
conventional diaphragm-type air pump.
DETAILED DESCRIPTION
Referring now to the accompanying drawings, there is explained a
diaphragm-type air pump of the present embodiment. Firstly the first
invention is explained hereinafter.
In FIG. 1, numeral 1 is a core of an electromagnet having an approximately
E-shaped lateral section. The core 1 comprises a side pole 2 having a
U-shaped lateral section and a main pole 3 disposed at a center of the
side pole 2. Diaphragm-type air pumps according to the second and third
embodiments have the same plan view as in FIG. 1. The main pole 3 and/or
side pole 2 can be fabricated by incurvating laminated iron plate
consisting of 2 to 20 sheets of iron plates each having a thickness of 0.2
to 0.5 mm as shown in FIG. 2, by crooking an iron plate having a thickness
of 0.5 to 5 mm as shown in FIG. 3, or by laminating 10 to 100 sheets of
cut and formed iron plates each having a thickness of 0.2 to 1 mm as shown
in FIG. 4. The main pole 3 and/or side pole 2 can also be fabricated by
crooking a laminated iron plate, by incurvating an iron plate, or by
concentrating magnetic powder such as dust iron core, of which embodiments
are not shown. FIG. 4 shows an E-shaped core consisting of laminated iron
plate obtained by modifying a conventional E-shaped core in accordance
with an idea of the first embodiment. In the specification, the term
"incurvating" means--bending with relatively large R (radius)--, and the
term "crooking" means--bending substantially without R, or folding--. In
FIGS. 2 and 3, the main pole 3 is fixed to the side pole 2 by means of
screws 4. The main pole 3 might be, however, fixed by other fixing
methods, for example, by adhesion.
The core 1 shown in FIGS. 2 and 3 comprises the main pole 3 and the side
pole 2 which are fabricated separately. Thanks to this separate structure,
a coil bobbin around which coils are wound almost to a width of vacant
space for coils (not shown) can be attached to the core 1. That is, when
forming a main pole and a side pole in one body, a coil bobbin having a
large amount of coils therearound so as to effectively utilize a wide
width of vacant space for coils cannot be attached to the main pole. On
the other hand, when forming a main pole and a side pole separately, an
electromagnetic coil can be assembled by putting a coil bobbin having
fully wound coils on a main pole 3, inserting the main pole 3 in the side
pole 2 from above the side pole 2, and combining the main pole 3 and the
side pole 2 by means of screws 4 and the like.
In the core 1, there is disposed a coil frame 5, made of 6,6-nylon and the
like, which contacts the main pole 3. Copper wires are wound around the
coil frame 5 to constitute a coil 6. An electromagnetic coil A consists of
the core 1, coil frame 5 and coil 6.
A rod 8 having two permanent magnets 7a, 7b is disposed halfway between a
pair of electromagnetic coils A. Both end portions of the rod 8 are
connected to diaphragms 10 made of EPT (Ethylene Propylene Terpolymer) and
the like through center plates 9. Center plates 9 are provided at both
sides of the diaphragm 10, and push or pull the diaphragm 10 to move it
right and left in FIG. 1. The center plates 9 and diaphragm 10 are
sandwiched between a nut 11 and an attaching seat 12, and are fixed to a
tip of the rod 8 by clamping with the nut 12.
An outer periphery of the diaphragm 10 is seated within a circular recess
defined by a casing 15 and a diaphragm stand 14 made of PBT (Polybutylene
Terephthalate) and the like which is fixed to the side pole 2 by a bolt. A
recess 16 defined by the diaphragm 10 and the casing 15 functions as a
compression chamber.
The casing 15 includes a suction room 17 and a discharge room 18 besides
the above recess 16. A communicating hole 17a is formed on a partition
wall between the suction room 17 and the compression chamber, and a
communicating hole 18a is formed on a partition wall between the discharge
room 18 and the compression chamber. A suction valve 17b and a discharge
valve 18b are respectively provided at the communicating hole 17a and
communicating hole 18b. Numeral 18c is a discharge port whereto a tube
(not shown) and the like is connected.
The casing 15 is made of PBT and the like, and is fixed to the side pole by
means of a bolt together with the diaphragm stand 14 in the embodiment of
FIG. 1. In FIG. 1, a right diaphragm and a casing are depicted as a plan
view, so that the insides thereof are not shown. They have, however, the
same constitution as in left portion described hereinbefore.
Next there is briefly explained an operation of the diaphragm-type air pump
of the present embodiment.
The flow of alternating current in the electromagnetic coil A alternately
generates a north pole and a south pole at both ends of the
electromagnetic coil A corresponding to the change of alternating current.
Then the main pole and side pole, both of which are made of magnetic
substance, are magnetized corresponding to the change of alternating
current, whereby alternately generating different polarity at both ends of
the main pole and side pole.
In a certain half-wave length of alternating current, the end of the side
pole is magnetized to be a south pole when the end of the main pole is
magnetized to be a north pole. In that case, attraction acts between the
permanent magnet 7a and an end 20a of the side pole, and between the
permanent magnet 7b and an end 21b of the main pole. On the other hand,
repulsion acts between the permanent magnet 7b and the end 20b of the side
pole, and between the permanent magnet 7a and the end 21a of the main
pole. Thus the rod 8 moves to the left in FIG. 1. When alternating current
changes from the above-mentioned half-wave length to a next half-wave
length, the repulsion changes to attraction and the attraction changes to
repulsion, so that the rod moves to the right.
Thus the rod reciprocates from right to left corresponding to the frequency
of alternating current. The diaphragm 10 vibrates from right to left
according to the movement of the rod 8. When the rod 8 moves to the right,
the suction valve 17b opens while the discharge valve 18b is closed. Fluid
which is introduced into the suction room 17 through the suction hole 19a
and the vent hole 19b enters the compression chamber through the
communicating hole 17a. When the rod 8 moves to the right, the discharge
valve 18b opens while the suction valve 17b is closed. Fluid in the
compression chamber is discharged from the discharge port 18c through the
communicating hole 18a and the discharge room 18. In this way, the
diaphragm-type air pump of the present invention drives.
The distinguishing feature of the diaphragm-type air pump of the first
embodiment having a constitution as stated above resides in a constitution
of core of the electromagnetic coil. That is, in the first embodiment, a
main pole and/or side pole are/is separately fabricated by incurvating or
crooking laminated iron plate or single iron plate, or laminating iron
plates which are cut and formed beforehand. A core is formed by
incorporating or uniting the main pole and the side pole on assemblying an
electromagnetic coil. In that case, a distance between the main pole and
side pole is enlarged. Further, tips of the main pole and side pole
approach to each other by bending or protruding a tip of at least one of
the main pole and side pole toward a tip of the other pole, or by fixing a
previously prepared tip portion to at least one of the main pole and side
pole in such a manner that tips of both poles approach to each other. In
the above-mentioned core, permeance coefficient is decreased due to a
large distance between the main pole and side pole, so that leakage
magnetic flux is reduced. Further, gap magnetic flux is increased since
the tip of the main pole and that of the side pole approach to each other
to make a working gap l small (see FIG. 5). In this way, the
electromagnetic core in the first embodiment can reduce leakage magnetic
flux which has been a drawback of conventional electromagnetic cores, and
increase gap magnetic flux which directly influences on the magnitude of
magnetic mutual action with a permanent magnet, so that magnetic flux
generated in the electromagnetic coil can be extremely effectively
utilized. Moreover, according to the first embodiment, the width of the
permanent magnet can be narrowed so that magnetic attracting portion can
be lengthened according to the amount of decreased permanent magnetic as
long as tuning between characteristic frequency determined by elasticity
of the diaphragm and weight of a rod portion and frequency of power source
can be maintained. Thus, output of pumps can be increased and pump
efficiency can be improved. That is, the width C and length B of the
permanent magnet can be changed, while keeping the size D shown in FIG. 6a
constant, into C.sub.1 (=C/2) and B.sub.1 (=2B) as shown in FIGS. 7a and
7b. In that case, the area of magnetic attracting surface (A.sub.1
.times.B.sub.1) of the air pump of the first embodiment shown in FIGS. 7a
and 7b is twice as large as that (A.times.B) of conventional air pump.
Accordingly, strong vibration power can be obtained whereby improving the
pump capacity. The density of gap magnetic flux can be increased still
more when the crooked tip of the side pole is partially cut to make the
height of side pole equal to that of main pole, as shown in FIG. 3.
Next the second embodiment is explained. The second embodiment has a
feature that a winding core has a small sectional area and that a
supplementary magnetic path is provided at a tip of a main pole at the
side of a permanent magnet. That is, an air pump according to the second
embodiment can change a magnetic path of low magnetic flux density in the
conventional electromagnet into a magnetic path of high magnetic flux
density on the basis of an idea that a slender winding core can
effectively reduce the amount of wire used while maintaining the same
magnetomotive force. A very slender iron core (see FIG. 10) is employed in
the second embodiment.
However, when the sectional area of the main pole is made small, i.e. the
winding core is made slender, attraction or repulsion which functions
between the main pole and permanent magnet is weakened because a portion
of the main pole functioning with the permanent magnet is small. Further,
corresponding magnetic surface with the side pole and permeance
coefficient become small so that gap magnetic flux is reduced. The
supplementary magnetic path in a diaphragm-type air pump of the second
embodiment prevents the fall of magnetic mutual function between an
electromagnet and a permanent magnet.
In FIG. 1 (which also shows a plan view of a diaphragm-type air pump of the
second embodiment as stated above), FIG. 8 and FIG. 9, numeral 1 is a core
of an electromagnet having an approximately E-shaped lateral section. The
core 1 comprises a side pole 2 having a U-shaped lateral section, a main
pole 3 disposed at a center of the side pole 2, and supplementary magnetic
path 40 provided at a tip of the main pole 3. The main pole 3 and/or side
pole 2 and/or supplementary magnetic path 40 can be fabricated by crooking
an iron plate having a thickness of 0.5 to 5 mm, by incurvating a
laminated iron plate consisting of 2 to 20 sheets of iron plates each
having a thickness of 0.2 to 0.5 mm, by crooking laminated iron plate, or
by incurvating an iron plate. They can also be fabricated by concentrating
magnetic powder such as dust iron core. In FIGS. 8 and 9, the main pole 3
is fixed to the side pole 2 by means of screws 4. The main pole 3 might
be, however, fixed by other fixing methods, for example, by adhesion. The
supplementary magnetic path 40 prevents the fall of magnetic mutual
function between the main pole 3 and permanent magnet due to the reduction
of magnetic attracting portion of the main pole 3 with the permanent
magnet, as sectional area of the main pole 3 is reduced to save the amount
of coils to be used. The supplementary magnetic path 40 also increases
corresponding magnetic surface with the side pole to increase permeance
coefficient and gap magnetic flux. The supplementary magnetic path 40
might be L-shaped plate members to be attached on the upper and bottom
surfaces of the rectangular main pole as shown in FIG. 8. In that case,
shorter sides of the L-shaped members function as a supplementary magnetic
path. The supplementary magnetic path 40 might be a plate member to be
attached to the front of the main pole. In that case, a portion extending
from the front of the main pole 3 functions as a supplementary magnetic
path. FIG. 10 shows a core obtained by modifying a E-shaped core of the
first embodiment shown in FIG. 4 according to an idea of the second
embodiment, wherein the whole core is made slender and a supplementary
magnetic path is attached to the front of the main pole having a small
sectional area. In the core of FIG. 10, the size of vacant space for coils
a'.times.b' becomes larger than the conventional E-shaped core. The
supplementary magnetic path 40 and main pole 3 might be fabricated in one
body, or might be separately fabricated and assembled thereafter.
A feature of the diaphragm-type air pump of the second embodiment resides
in providing supplementary magnetic paths as stated above at a main pole
having a reduced sectional area. The supplementary magnetic path widens
and lengthens a portion of the main pole working with permanent magnets,
and enlarges a magnetic path corresponding to the side pole, so that the
magnetic embodiment between the electromagnet and permanent magnets can be
strengthened. Thus, disadvantages accompanying the reduction of sectional
area of the main pole for saving coils can be solved. In this connection,
it is preferable that the height of the supplementary magnetic paths are
approximately equal, when provided at the main pole, to that of side pole
and permanent magnets. The width of the supplementary magnetic path might
be larger than that of the main pole.
Further, according to the second embodiment, inefficient and irrational use
of magnetic flux caused by the difference of magnetic flux density between
permanent magnet and electromagnet can be solved.
That is, when a permanent magnet extended in its longitudinal direction in
accordance with the first embodiment, for example, ferrite magnet, the
magnetic flux density (.PHI..sub.1) at a magnetic attracting surface is
about 2000 gauss. On the other hand, the magnetic flux density
(.PHI..sub.2) of a usual electromagnet is as much as 6000 gauss.
Therefore, the proportion of area of magnetic attracting surface might be
three to one from a viewpoint of the quantities of magnetic flux effecting
each other. In that case, passage of magnetic fluxes change with respect
to magnetic attracting surfaces, so that the use of magnetic fluxes
becomes extremely irrational and inefficient.
On the other hand, when the supplementary magnetic path is employed like an
air pump according to the second embodiment, magnetic fluxes are dispersed
as shown in FIG. 11b so that magnetic flux density of the electromagnet is
reduced to about 2000 gauss. Accordingly rational and efficient embodiment
is obtained between the permanent magnet and electromagnet. That is,
though the magnetic flux density at a place where lines of magnetic force
generate is high because of the small sectional area of an iron core,
attracting force between permanent magnet and electromagnet can be
extremely effectively utilized at a magnetic attracting surface since
lines of magnetic force are distributed through the supplementary magnetic
path to such a place that gives good efficiency.
Next the third embodiment is explained. The third embodiment improves the
limitation of effective utilization of magnetic flux, of which limitation
is due to the use of a single main pole. That is, even in electromagnets
according to the first and second embodiments, the increased ratio of
copper wire is enlarged with the increase of sectional area of the main
pole when pump capacity becomes twice or three times. The use of copper
wire therefore becomes uneconomical and inefficient. When the sectional
area of the main pole is small, it does not require much copper wire to
wind the main pole one time. However, the sectional area of the main pole
is enlarged as copper wire is wound around the main pole, so that an
amount of copper wire per one winding is gradually increased. Further, in
a middle-sized pump (such a pump that has a pump output of about 30 to 80
l./min.), a supplementary magnetic path can be composed of steel sheets of
about 2 to 3 mm. thick since magnetic flux density at a portion S.sub.1 of
the supplementary magnetic path is not so high as shown in FIG. 14a.
However, in the case of a large-sized pump (such a pump that has a pump
output of about not less than 120 l./min.), the amount of magnetic flux
passing through a portion S.sub.2 increases rapidly so that the thickness
of steel sheet is required to be increased depending on the increase of
magnetic flux. In that case, core loss due to the thickness of steel
sheets is rapidly increased and heat generates increasingly. In order to
prevent the core loss and heat generation, it is necessary to use
laminated ten and a few steel sheets of 0.2 to 0.5 mm. thich and therefore
the structure of the supplementary magnetic path becomes very complicated.
The third embodiment solves the problem that the amount of copper wire
used is increased inefficiently and that the structure of the
supplementary magnetic path becomes very complicated, and is characterized
in that a core of an electromagnet comprises a plurality of main poles and
a side pole.
FIGS. 12 and 13 are schematic perspective views of examples of
electromagnets in diaphragm-type air pumps according to the third
embodiment. In FIG. 12, numeral 1 is a core of an electromagnet having an
approximately E-shaped lateral section. The core 1 comprises a side pole 2
having a U-shaped lateral section and two main poles 3 disposed at a
center of the side pole 2. The main poles 3 are arranged perpendicular to
a vibration direction of a rod 8 of the diaphragm-type air pump (see FIG.
1). In the example of FIG. 13, two main poles are arranged parallel to a
vibration direction of the rod. In that case, it is necessary to provide a
supplementary pole 6 between two main poles to enlarge acting surface and
to adjust polarity of the core. The number of main poles is not limited to
two as in FIGS. 12 and 13, but might be not less than three. The main
poles might be arranged two-dimensionally, i.e. both vertical and parallel
to a vibration direction of the rod. The main pole 3 and/or side pole 2
can be fabricated by incurvating a laminated iron plate consisting of 2 to
20 sheets of iron plates each having a thickness of 0.2 to 0.5 mm as shown
in FIG. 2, by crooking an iron plate having a thickness of 0.5 to 5 mm as
shown in FIG. 3, or by laminating 10 to 100 sheets of cut and formed iron
plates each having a thickness of 0.2 to 1 mm as shown in FIG. 4. The main
pole 3 and/or side pole 2 can also be fabricated by crooking a laminated
iron plate, by incurvating an iron plate, or by concentrating magnetic
powder such as dust iron core, of which embodiments are not shown.
A distinguishing feature of the third embodiment resides in a point that an
electromagnet core consists of a plurality of main poles 3 and a side pole
2. By the use of a plurality of main poles, there can be reduced an amount
of copper wire used for the same magnetomotive force, i.e. ampere-turn
(IN). Further, main poles of the same specification can be applied to
various kinds of pumps, i.e. from small-sized pumps to large-sized pumps.
From a viewpoint of effective utilization of a width of vacant space for
coils, it is preferable that the main pole 3 and side pole 2 are
separately fabricated; the main pole 3, around which a coil bobbin is set,
is inserted in the side pole 2 from above the side pole 2; and then the
main pole 3 is fixed to the side pole 2 by means of screws and the like,
as shown in FIGS. 11 and 12. In that case, the fixation of the main pole 3
and side pole 2 can be carried out by other means such as adhesion.
When supplementary magnetic paths 40 are provided, as shown in FIG. 13, at
tips of main poles at the side of permanent magnets, the magnetic
attracting portion of main poles with permanent magnets are enlarged so
that attraction or repulsion between main poles including supplementary
magnetic paths and permanent magnets can be increased. Further, a magnetic
path corresponding to the side pole is enlarged and permeance coefficient
is increased, whereby increasing mutual electromagnetic force between the
main poles and side pole. From a viewpoint of sufficiently producing the
effects, it is preferable that the height of the supplementary magnetic
paths is approximately equal, when provided at the main pole, to that of
the side pole and permanent magnets. The width of the supplementary
magnetic paths might be larger than that of the main poles. The
supplementary magnetic paths can be fabricated by the same materials and
methods as in the above-mentioned main pole 3 and side pole 2.
As described above, the diaphragm-type air pump of the present embodiment
enables the improvement of pump capacity and the lightening of pumps.
To say more precisely, in the first embodiment, a distance between a main
pole and a side pole is enlarged, so that the number of windings of coils
and the amount of magnetic flux can be increased. Further, by the
enlargement of the distance, permeance coefficient is decreased and
accordingly leakage magnetic flux is reduced. Still further, gap magnetic
flux can be increased because the tips of main pole and side pole approach
to each other. In this way, the first embodiment enables extremely
effective utilization of magnetic flux generated by electromagnetic coil,
whereby strengthening a vibration force of a rod and remarkably improving
discharge capacity of pumps. The weight of a core can be reduced compared
to conventional E-shaped cores, whereby pumps can be lightened. Moreover,
there can be omitted the use of conventional frames serving to contain
electromagnetic coils and rods and to fix diaphragm tables and casings,
since diaphragm tables and casings can be directly fixed to side poles.
That is, a conventional air pump having a frame 100 as shown in FIG. 17
can be miniaturized to an air pump shown in FIG. 1. The size of a' and b'
(see FIG. 17) can be reduced, for example, by about 20 to 30%. In other
words, the size of a and b in FIG. 1 are respectively about 70 to 80% of
a' and b' in FIG. 17.
In the diaphragm-type air pump of the second embodiment, an amount of coils
used can be reduced for obtaining the same magnetomotive force, since the
sectional area of the main pole, i.e. winding core, is decreased.
Accordingly pumps can be lightened and miniaturized. Further, the
supplementary magnetic path is provided at the main pole having reduced
sectional area, so that a magnetic path corresponding to the side pole is
enlarged to increase permeance coefficient, and gap magnetic flux is
increased. The magnetic attracting portion with permanent magnets is
widened and lengthened, so that magnetic interaction between the
electromagnet and permanent magnets can be strengthened. Therefore, air
pumps of large capacity in spite of small size and light weight can be
obtained.
Moreover, in the diaphragm-type air pump of the third embodiment, an amount
of copper wire used can be reduced to obtain the same magnetomotive force,
i.e. ampere-turn (IN). Parts of the same specification can be applied to
various kinds of pumps by changing the number of parts to be used.
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