Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Scroll or helical type casing with specific exit nozzle
Reexamination Certificate
2000-08-30
2003-01-28
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Scroll or helical type casing with specific exit nozzle
C415S214100, C285S322000, C285S361000, C403S265000
Reexamination Certificate
active
06511290
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to blowers used on high efficiency furnaces and, more particularly, to an exhaust interface formed on a discharge pipe of a blower housing.
(2) Background of the Invention
Blowers are commonly used in high efficiency furnaces (e.g. 90% efficiency) for drawing combustion air into the furnace and for removing exhaust gases from the furnace. Generally, these blowers are located downstream of a combustion chamber or combustion tubes in the furnace, depending upon the style of furnace, and propel exhaust gases out the furnace through an exhaust pipe that vents to outside atmosphere.
FIGS. 1 and 2
show the typical arrangement of a blower
20
of the prior art. The blower
20
includes a blower motor
22
and a blower housing
24
. In
FIG. 1A
, the blower motor has been removed from its center mount
26
on top of the blower housing
24
to show greater detail of the blower housing
24
. The blower housing
24
has an upstanding annular wall
28
extending between a top piece
30
and a bottom piece
32
. The top piece
30
is molded to include the center mount recess
26
to receive the blower motor
22
. The annular wall
28
, top piece
30
, and bottom piece
32
form a volute
34
for the blower housing
24
. An impeller
22
, operably connected to a shaft of the blower motor
22
rotates in the volute
34
when the blower
20
is energized to draw exhaust gases through an inlet hole (not shown) in the center of the bottom piece
32
. The gases are then compressed in the volute
34
and directed into a discharge pipe
36
that extends outward and away from the volute
34
.
FIG. 2
shows the general arrangement of the blower installed in a furnace
38
. The blower is mounted on a blower mounting surface
40
on the furnace
38
where the inlet hole (not shown) of the blower housing
24
is positioned to allow the impeller to draw exhaust gases directly from the combustion chamber or combustion tubes (not shown) into the blower housing
24
. The discharge pipe
36
is coupled to an exhaust pipe
42
using a double booted rubber gasket
46
to vent the exhaust gases to atmosphere. In the prior art, the blower housing
24
and exhaust pipe
42
are commonly made from a polypropylene or polyvinyl chloride (PVC) plastic material.
Greater detail of the double booted gasket
46
of the prior art is shown in FIG.
1
B. The double booted rubber gasket
46
is a cylindrically shaped tubular member with first and second ends
48
,
50
. The first end
48
has a first internal annular groove
52
that forms a first annular socket
54
that fits on a boss end
56
of the discharge pipe
36
of the blower housing
24
. To secure the double booted rubber gasket
46
to the discharge pipe
36
of the blower housing
24
, a first hose clamp
58
is typically used. The second end
50
of the double booted gasket
46
has a similar arrangement with a tubular insert
60
concentrically disposed within the gasket
46
to form a second internal annular groove
62
. The exhaust pipe
42
is received within the second internal annular groove
62
and is secured to the double booted gasket
46
by tightening a second hose clamp
64
. The second internal annular groove
62
has a groove root
66
with baffles
68
to collect condensate that is entrained in the exhaust gas stream. This condensate is collected at the root
66
and is removed from the double booted gasket
46
through drain portals
70
on the sides of the double booted gasket
46
that communicate with the groove root
66
.
The use of the double booted gasket
46
has several drawbacks. The double booted gasket
46
is a complex part that must be manufactured in an intricate molding process. Because the gasket
46
is an added part to be fitted between the blower housing
24
and the exhaust pipe
42
, it complicates the installation process. Further, as is readily apparent to those of skill in the art, a pair of pipe clamps must be aligned and screwed tight to complete the installation which takes some time and careful attention. The added part also increases the expense of the blower
20
and the installation of the blower
20
on the furnace
38
.
The double booted gasket
46
must also be made from a relatively strong material that must withstand industry standards for mechanical strength and exhaust system integrity. Generally, in this application on a high efficiency furnace, the double booted gasket
46
must be able to maintain its connection to the discharge pipe
36
with a 25 ft-lb torque exerted on the exhaust pipe
42
(the “twist” condition). The gasket
46
must also maintain its connection to the discharge pipe
36
with a 50 lb. parallel pull out force exerted axially along the exhaust pipe
42
(the “pull-out” condition). Because the double booted gasket
46
has one hose clamp connection with the discharge pipe
36
and another hose clamp connection with the exhaust pipe
42
, the double booted gasket
46
has two points for failure. Thus, the gasket
46
is susceptible to failure at either one of these two connections which represent the most likely point of failure.
What is needed in the art is a method of improving the connection between the blower housing
24
and the exhaust pipe
36
such that the industry standard mechanical tests for strength and exhaust system integrity are maintained while providing a less expensive part with an easier install procedure.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an exhaust interface for a blower that simplifies the connection between the blower housing and the exhaust pipe while meeting the requisite industry standards for strength and exhaust system integrity.
The blower of the present invention includes a blower housing and a blower motor. The blower housing has an impeller and a discharge pipe for directing exhaust gases out and away from the blower. The discharge pipe has a first end that is formed adjacent the housing and an opposite second end that is spaced from the housing, or volute. The second end includes an exhaust flange with an annular socket and a plurality of resilient teeth extending axially outwardly from the second end and circumferentially spaced around the annular socket.
The blower includes an exhaust fitting that has an outer cylinder with a front end and an axially opposite back end, and a generally tubular insert disposed within the outer cylinder. An annular back wall extends between the outer cylinder and tubular insert. The tubular insert is attached to the annular back wall at the back end of the outer cylinder such that the tubular insert extends outward and away from the back wall and through the front end of the outer cylinder. The tubular insert forms an annular groove in the front end of the exhaust fitting.
The exhaust fitting is received in the annular socket of the exhaust flange, and the exhaust pipe is received in the annular groove. A clamping means such as preferably a pipe clamp for radially compressing the plurality of circumferentialy spaced teeth on the exhaust flange may be used to secure the exhaust pipe within the exhaust fitting and the exhaust fitting within the annular socket of the exhaust flange.
The exhaust fitting and exhaust flange are preferably keyed so that the exhaust fitting may be assembled in the annual socket on the exhaust flange in only one circumferential orientation. The exhaust flange preferably has an integral drain for removing condensate in the exhaust gases. In this configuration, the exhaust fitting may have a guttering system adjacent the back wall of the annular groove that directs condensate from the exhaust pipe into the drain on the exhaust flange. Preferably, each of the circumferentialy spaced teeth has a proximal end which is cantileverly attached to the second end of the discharge pipe and a distal end which is spaced away from the proximal end. The distal end of each of the teeth may have an annular ridge that extends radially outward and engages a portion of the clamping
Jakel Incorporated
Look Edward K.
McAleenan James M
Thompson & Coburn LLP
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