Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Casing with mounting means
Reexamination Certificate
2002-09-17
2004-08-24
Nguyen, Ninh H. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Casing with mounting means
C415S214100, C415S220000
Reexamination Certificate
active
06779975
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Japanese application serial no. 2001-284160, filed on Sep. 18, 2001 and 2002-234545, filed on Aug. 12, 2002.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a duct fan unit which is used for ventilating as a cooling device in various machines wherein a case thereof receives heat generation members such as a motor, a coil and a heater etc.
2. Description of the Related Art
In order to prevent temperature buildup inside a case due to continuous heat generation from the heat generation members that are disposed inside the case, such as a motor, a coil, a heater and a heat generation circuit etc., in an image forming apparatus, a communication equipment, other electrical equipment or various mechanism, a fan is used. The fan ventilates the heat generation member by removing the air inside the case to the outside. Thus the heat generated around the heat generation members can be radiated to outside.
It is well known that a fan and a duct are assembled to form a duct fan unit to achieve the function described above.
FIG. 2
is a perspective view showing disassembling of a conventional duct fan unit. The duct
1
is generally made of resin. The duct
1
is disposed at a predetermined location inside a case containing a heat generation unit. The duct
1
is designed into a shape suitable for influx and exhaust of air. A fan
5
is embedded and fixed onto the inner wall of an opening
1
a
at one end of the duct
1
. The other end
1
b
of the duct
1
is attached to a vent hole set on a case (not shown). The fan
5
comprises a motor (not shown) disposed inside the outer frame
6
and blades
7
driven by the motor to rotate. In this example, the fan
5
is fixed onto the duct
1
as described below. Screw receivers
2
are for example are set on four corners of the duct
1
, and through holes
6
a
corresponding to these screw receivers
2
are set on the outer frame
6
of the fan
5
. Long screws
8
are driven through the through holes
6
a
and into the screw receivers
2
in order to fix the fan
5
onto the duct
1
.
However, in the conventional duct fan unit, because the screws
8
are used to fix the fan
5
inside the duct
1
, not only the assembly operation but also the disassembling operation is complicated. Thus both assembly and disassembly operations becomes very inconvenient and therefore cannot be effective.
The Japanese Laid-Open publication no. 2000-22375 discloses a structure in which the fan unit can be easily replaced when the fan unit is out of order. The structure is shown as
FIGS. 3A and 3B
, a resilient plate
42
and an engaging plate
43
are used to fix the fan unit
41
onto the fixing portion
44
. The resilient plate
42
is in contact with one side of the fan unit
41
and the resilient plate
42
presses the fan unit
41
to one side. The engaging plate
43
disposed opposite to the resilient plate
42
is latched to the fan unit
41
and the engaging plate
43
fixes the fan unit
41
at a predetermined position. Structure members for limiting the positions of the resilient plate
42
or the engaging plate
43
and the fan unit
41
, such as limiting portions
45
,
46
etc. are integrally formed with the duct frame
40
that receives a heat generation unit. Furthermore, the resilient plate
42
and the engaging plate
43
are perpendicular to the flow passage of the cooling air of the fan unit
41
.
In spite of the simplified assembly and disassembly operations facilitated by the structure disclosed in the Japanese Laid-Open publication no. 2000-22375, however, it can be understood from the drawings that the structure is very complicated. Therefore, the manufacture cost becomes high.
Another Japanese Laid-Open publication no. He7-92862 as shown in
FIG. 4
, discloses a structure comprising a duct which is assembled by a pair of duct constructing members
51
,
52
for ventilating air and a fan
53
that is clamped and supported within the duct by the pair of duct constructing members
51
,
52
. The plane of engagement of the pair of duct constructing members
51
,
52
of the duct is substantially along the air flow direction. When assembling, the fan
53
is positioned and clamped by using guide ribs
56
,
57
that are formed as an individual pair of ribs on the inner wall of the duct constructing members
51
,
52
, so that a duct is formed, then the duct constructing members
51
,
52
are secured by the fastening screws. A duct case
55
where an ozone filter
54
is inserted to an end of the duct is fixed by screws. Each guide rib
56
,
57
is constructed by a pair of rib portions protruding perpendicular with respect to air flow direction.
In spite of the disassembly operation of the fan
53
from the duct facilitated by the structure disclosed in the Japanese Laid-Open publication no. He7-92862, the problem resulting from using the pair of guide ribs
56
,
57
to fix the fan
53
to a fixed position the fan
53
inside the duct occurs. When assembling, if the direction of the guide ribs
56
,
57
are not perpendicular to the air flow direction, the fan
53
cannot be clamped under the desired condition. Further, the duct constructing members
51
,
52
cannot be correctly assembled to construct the duct. Therefore, the formation of the duct constructing members
51
,
52
which are generally made of resin is required to be constructed under a precision conditions and thus the cost thereof is high. Furthermore, when the position of the guide ribs
56
,
57
gets slightly changed, attempts to assemble the fan
53
and the duct constructing members
51
,
52
by force may break the duct constructing members
51
,
52
.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a duct fan unit wherein the fan is installed inside a duct without those inconveniences described above. The structure of the duct fan unit is simpler and the operation of detaching the fan is easy and the manufacture cost can be decreased.
For solving the problems described above, another object of the present invention is to provide a duct fan unit wherein the fan is installed inside a duct to solve the inconvenience of detaching the fan as experienced by fixing the fan to the conventional duct using screws.
In accordance with the above objects and other advantages of the present invention, a structure of a duct fan unit is provided. The duct fan unit comprises a duct, at least a fan, at least a guide portion and at least a protrusion portion. The duct is divided into a pair of duct constructing members to allow air to pass through. The fan is clamped by the pair of duct constructing members and supported inside the duct, wherein a division direction of the duct is substantially along an air flow direction created by the fan. The guide portion is disposed at an inner wall of one of the duct constructing members to limit an installation position of the fan inside the duct. The guide portion extends from the inner wall of the duct member in a shape of a rib perpendicular to the division direction. The protrusion portion is disposed at an inner wall of the other duct constructing member to make contact with an outer wall of the fan and to resiliently press the fan towards a side of the duct constructing member. The protrusion portion protrudes towards a direction perpendicular to the division direction.
According to an aspect of the present invention, at a side wall where the protrusion portion is formed, a portion surrounding the protrusion portion is notched to form at least a pair of openings facing to each other.
According to another aspect of the present invention, the pair of openings is a pair of slots.
According to another aspect of the present invention, the duct fan unit comprises a duct and a fan. The duct allows air to pass through and the duct is divided into two duct constructing members along an axial direction of the duct. The fan is embedded on an inner wall of the duct. The fan is clamped by the two duct constructi
Matsumoto Kazuyoshi
Murano Jun'ichi
Shoji Katsunori
Takashima Osamu
Tsukamura Kiyoshi
Nguyen Ninh H.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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