Pumps – Expansible chamber type – Plural pumping chambers
Reexamination Certificate
2002-09-25
2004-04-06
Freay, Charles G. (Department: 3746)
Pumps
Expansible chamber type
Plural pumping chambers
C092S071000, C074S060000
Reexamination Certificate
active
06716005
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a pump provided with diaphragms, and more particularly to a compact pump which is used for a sphygmomanometer or the like.
A related-art compact pump of this type (disclosed in Japanese Patent Publication No. 2002-106471A) is now described with reference to
FIGS. 3
to
4
B. In
FIG. 3
, a compact pump
1
is provided with two diaphragms
4
for defining pump chambers
3
in a casing
2
which has a rectangular shape in a plan view. Hollow fitting members
5
are provided at respective center parts on a lower face of the diaphragms
4
so as to project downward from the diaphragms
4
, and there is arranged, below the diaphragms
4
, a pivotable member
6
which is adapted to move the lower faces of the diaphragms
4
up and down. The casing
2
is composed of three steps, namely, an upper case
2
a
, an intermediate case
2
b
, and a lower case
2
c
, and the diaphragms
4
are held in the casing
2
in such a manner that flange portions
4
a
of the diaphragms
4
are clamped between the upper case
2
a
and the intermediate case
2
b.
Moreover, shaft bodies
7
having intake holes
7
a
are provided on the pivotable member
6
in the vicinity of its outer peripheral ends and positioned below the respective center part of the diaphragms
4
so as to project upwardly. By tightly fitting inner faces of the hollow fitting members
5
provided on the diaphragms
4
to outer faces of these shaft members
7
, the diaphragms
4
can be mounted to the pivotable member
6
.
The diaphragms
4
are partly cut in the respective center parts of their bottoms in order to form air intake valve bodies
8
, and there are formed through holes
9
by the cut. The through holes
9
can be opened or closed by the air intake valve bodies
8
, thus constituting air intake valve sections V
1
.
Further, a vent hole
10
is formed in a center part of the upper case
2
a
, and two annular concave grooves
11
which open downward and communicate with the vent hole
10
are provided on a lower face of the upper case
2
a
at an outer circumference of the vent hole
10
. Vent valve bodies
12
consisting of upper end portions of the diaphragms
4
are fitted by pressure to inner wall faces
11
a
of the annular concave grooves
11
, thus constituting vent valve sections V
2
.
An eccentric rotation shaft
13
pierces through a center part of the pivotable member
6
. An extended portion
14
which is extended from the intermediate case
2
b
is provided above the pivotable member
6
, and a V-shaped recess
15
which opens downward is formed in a lower part of the extended portion
14
. An upper end portion of the eccentric rotation shaft
13
is loosely fitted in the recess
15
so as to swing freely therein. On the other hand, a rotary body
17
is fixed to an upper end of a rotary drive shaft
16
which is rotatably supported in an upright manner at a center of a lower part of the lower case
2
c
, and there is formed, as shown in
FIGS. 4A and 4B
, a hole
18
in a columnar shape having a determined diameter and a determined depth on an upper face of the rotary body
17
at a position eccentric from its center position. A lower end portion of the eccentric rotation shaft
13
is loosely fitted into the hole
18
so as to swing freely therein.
A motor casing
20
which contains a motor
19
connected to the rotary drive shaft
16
is directly connected to the lower case
2
c
. The lower case
2
c
is provided with a communicating hole
21
which communicates with the motor casing
20
, and in addition, air intake holes
22
are formed in a lower part of the motor casing
20
for introducing outside air into the motor casing
20
.
In this state, when the rotary drive shaft
16
is driven by the motor
19
to rotate and the rotary body
17
is rotated, the eccentric rotation shaft
13
is caused to rock inside the hole
18
, resulting in an eccentric rotation. This will cause a pivoting motion of the pivotable member
6
thereby to move the lower end portions of the diaphragms
4
up and down. When the lower end portion of one of the diaphragms
4
, for example, is moved downward, negative pressure is generated inside the diaphragm
4
, and the vent valve body
12
will be tightly fitted to the inner wall face
11
a
of the annular concave groove
11
. In other words, the vent valve section V
2
is closed, and the air intake valve body
8
opens the through hole
9
. In this manner, the air intake valve section V
1
is shifted into an open state, and air is introduced from the intake hole
7
a
into the diaphragm
4
, as shown by an arrow C.
Then, when the lower end portion of the diaphragm
4
is moved upward, high pressure will be generated in the diaphragm
4
, and the air intake valve body
8
closes the through hole
9
, shifting the air intake valve section V
1
into a closed state. At the same time, the vent valve body
12
is enlarged in diameter so as to depart from the inner wall face
11
a
, and the air is exhausted through the vent valve section V
2
, as shown by an arrow D. Specifically, the air exhausted from the vent valve body
12
passes the annular concave groove
11
and exhausted from the vent hole
10
to the exterior of the casing
2
.
Also with the upward movement of the diaphragm
4
, negative pressure will be generated in the lower case
2
c
, and the air existing in the motor casing
20
flows into the lower case via the communication hole
21
, as shown by an arrow E. This generates negative pressure inside the motor casing
20
, and the outside air is introduced into the motor casing
20
via the air intake hole
22
, as shown by an arrow F.
In the compact pump, since the hole
18
of the rotary body
17
is formed in a columnar shape, when the eccentric rotation shaft
13
is pivoted inside the hole
18
, the lower end portion of the eccentric rotation shaft
17
is violently swung with relatively large pivoting motion in a bottom portion of the hole
18
. Accordingly, there will be arisen so-called rattling with loud noises.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a pump provided with diaphragms, which is able to prevent rattling of the eccentric rotation shaft for moving the diaphragms up and down to eliminate noises.
In order to achieve the above object, according to the present invention, there is provided a pump, comprising:
a plurality of diaphragms, which define a plurality of pump chambers;
a pivotable member, attached to the diaphragms;
a rotator, formed with a first hole having a first diameter, which is arranged eccentrically from a rotation center of the rotator, and a second hole having a second diameter smaller than the first diameter, which is formed in a bottom of the first hole; and
a shaft member, which connects the rotator and the pivotable member so as to convert a rotation of the rotator into a pivotal movement of the pivotable member for sequentially deforming each diaphragm to vary a volume of each pressure chamber,
wherein one end of the shaft member is fitted into the second hole.
Preferably, a part of a circumferential edge of the first hole serves as a part of a circumferential edge of the second hole.
In this pump, owing to the small diameter hole, the pivoting motion of the one end portion of the shaft member can be made small. Therefore, the so-called rattling can be prevented, and noises can be remarkably eliminated.
REFERENCES:
patent: 2733665 (1956-02-01), Klopp
patent: 4565118 (1986-01-01), Girodin
patent: 5630351 (1997-05-01), Clucas
patent: 6397794 (2002-06-01), Sanderson et al.
Freay Charles G.
Mitsumi Electric Co. Ltd.
Whitham Curtis & Christofferson, PC
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