Rotary kinetic fluid motors or pumps – With means for re-entry of working fluid to blade set – Cross flow runner
Reexamination Certificate
2002-05-09
2004-02-17
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
With means for re-entry of working fluid to blade set
Cross flow runner
C415S119000, C415S203000, C165S122000, C062S262000
Reexamination Certificate
active
06692223
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an air conditioning apparatus such as an air conditioner, a dehumidifier and an air purifier, and more particularly to an air conditioning apparatus in which a cross flow fan is mounted to be used as a blowing means.
BACKGROUND ART
Hereafter, a description will be made of an air conditioning apparatus, such as an air conditioner, a dehumidifier and an air purifier, in which a conventional cross flow fan is mounted. An example of the conventional cross flow fan entitled “Indoor Unit for Air Conditioner” is disclosed in Japanese Unexamined Patent Publication No. Hei 11-83062, for instance.
FIG. 50
is a longitudinal cross-sectional view of the main body of an air conditioning apparatus disclosed in Japanese Unexamined Patent Publication No. Hei 11-83062.
FIG. 51
is a perspective view of the impeller of a conventional cross flow fan.
FIG. 52
is a longitudinal cross-sectional view of the cross flow fan of FIG.
51
.
FIG. 53
is a cross-sectional view of a vane shown in FIG.
52
.
FIG. 54
is a diagram illustrating the frequency characteristic of noise of the air conditioning apparatus in which the conventional cross flow fan is mounted.
With referring to
FIGS. 50
,
51
and
52
, the conventional cross flow fan is formed by an impeller
101
, a guide wall
102
, a stabilizer
103
, and a motor
104
. The impeller
101
is formed by two or more units
110
a
which are connected in the direction of the shaft, each unit being formed by a plurality of vanes
101
b
and a ring
101
c
for supporting the plurality of vanes. The guide wall
102
surrounds the impeller
101
in such a manner as to cover one side of the peripheral surface of the impeller
101
. The stabilizer
103
is disposed in such a manner as to face the guide wall
102
. The motor
104
rotates and operates the impeller
101
as indicated by an arrow J.
According to the air conditioning apparatus in which the thus configured conventional cross flow fan is mounted, as shown in
FIG. 50
, air is sucked in through a detachable front facing grill and a detachable top facing inlet grill, then dust is removed from the air by using a filter, and thereafter the air is heated or refrigerated by means of a heat exchanger which is formed in such a manner as to surround the impeller
101
. Heat-exchanged air after passing through the heat exchanger is sucked into the impeller
101
, passes through a row of vanes on the side of the heat exchanger, and then is blown off again through a row of vanes on the side of an air outlet. Then, the air is blown off through the air outlet to the room by blowing-direction changing vanes, including up/down vanes and left/right vanes, changing the blowing direction of the air. Thus, the room is air-conditioned.
With referring now to the vane
101
b
in a cross-sectional shape shown in
FIG. 53
, a reference numeral A
20
denotes a tip of a vane's peripheral end portion A
2
in the shape of a circular arc of the vane
101
b
. A reference numeral A
10
denotes a tip of a vane's internal circumferential end portion A
1
in the shape of a circular arc of the vane
101
b
. A reference mark O denotes the center of the rotating shaft of the impeller
101
, and a reference numeral
1
denotes the center of a camber line P
0
formed into a single circular arc of the vane
101
b
. A reference numeral P
2
denotes a pressure face of the vane
101
b
on a side facing the direction of rotation of the impeller, and a reference numeral P
3
denotes a suction surface opposing to the pressure face P
2
. O-A
20
indicates a first straight line connecting the tip of the vane's peripheral end portion A
20
of the vane
101
b
and the center O. O
1
-A
20
indicates a second straight line connecting the tip of the vane's peripheral end portion A
20
of the vane
101
b
and the center O
1
of the camber line P
0
. Further, a reference mark n denotes a first perpendicular of the first straight line O-A
20
to the tip of the vane's peripheral end portion A
20
, and a reference mark m denotes a second perpendicular of the second straight line O
1
-A
20
to the tip of the vane's peripheral end portion A
20
. An exit angle &bgr;
2
is an acute angle formed by the first perpendicular and the second perpendicular.
With referring to the cross flow fan, for example, by expanding the outside diameter &phgr;D
2
of the impeller
101
in a similar shape, the flow rate is increased and the noise level is lowered. However, if the flow rate is increased and the noise level is lowered in such a manner, singular noise S
1
is generated in a low frequency range as shown in the diagram illustrating the frequency characteristic of noise of FIG.
54
. In addition to that, there may be a case where the noise level at the same flow rate is increased and a resultant atmosphere to the ear is made worse. For that reason, according to the conventional cross flow fan, the singular noise S
1
is tried to be reduced by setting the exit angle &bgr;
2
of the vane
101
b
to 23 degrees or less. Furthermore, by setting the exit angle &bgr;
2
to 18 degrees or more, the noise level at the same flow rate is lowered and a resultant atmosphere to the ear is controlled not to be aggravated.
Furthermore, by forming the vane
101
b
such that t
max
/t
min =
1.3~1.5, a blowing performance at a high flow rate may be obtained, where t
max
denotes a maximum thickness of the vane
101
b
and t
min
denotes the thickness of the vane's peripheral end portion, which is the thickness of a portion of the vane
101
excluding a roundish portion at a mounting end of the vane
101
on the vane's peripheral side. In addition to that, this also allows to obtain an interior unit of an air conditioner which has less opportunities of generating the singular noise in a low frequency range.
However, according to an air conditioning apparatus using the conventional cross flow fan disclosed in Japanese Unexamined Patent Publication No. Heill-83062, in the case that the suction resistance of the impeller
101
becomes high due to a decrease in the fin pitch of the heat exchanger, or dust accumulated on the filter, a circulating vortex C
1
caused near the stabilizer
103
, which is a typical phenomenon of a cross flow fan, may develop from a solid circle to a broken bold circle. Then, air after passing through the heat exchanger flows towards a cross flow vortex having a lower pressure, and then sucked into the impeller
101
as indicated by the arrow of FIG.
50
. As a result, in an area F
1
, the flow of air may be detached from the vane
101
b
, and then an air turbulent vortex G
1
may be generated at a rear portion of the vane
101
b
. Consequently, as shown in the diagram illustrating the frequency characteristic of noise of
FIG. 54
, there may be a case where the singular noise Sm having a frequency width fs is generated in a low frequency range of around 40 to 80 percent of the generation frequency of the rotation noise (NZ sound) depending upon the number of vanes Z and the rotational frequency N [r.p.m] of the impeller
101
. For that reason, a jarring noise other than the rotational noise may be generated, which produces an aggravated atmosphere to the ear, and this has been a problem.
Furthermore, because the vane's exit angle &bgr;
2
is reduced, thereby narrowing a vane's distance, when the flow of air passes between vanes, a resistance occurs. As a result, the shaft output for operating the impeller is increased, which increases the power consumption of the motor.
Hence, the present invention has been devised to solve the above described problems, and an object is to obtain an air conditioning apparatus which provides a favorable atmosphere to the ear and saves energy by controlling noise not to be aggravated even if the suction resistance of the impeller becomes high due to such as noise and dust during its operation, and further, by minimizing the generation of the singular noise in a low frequency range and the rotation noise, and minimiz
Ikeda Takashi
Morishita Kunihiro
Nakagawa Hidetomo
Tanabe Yoshihiro
Yoshihashi Makoto
Look Edward K.
McAleenan J. M.
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