Information
-
Patent Grant
-
6808365
-
Patent Number
6,808,365
-
Date Filed
Friday, January 31, 200321 years ago
-
Date Issued
Tuesday, October 26, 200419 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Look; Edward K.
- Kershteyn; Igor
Agents
- Birch, Stewart, Kolasch & Birch, LLP
-
CPC
-
US Classifications
Field of Search
US
- 415 2141
- 415 1701
- 415 1742
- 415 2082
- 415 2083
- 415 2084
- 415 2111
- 415 2112
-
International Classifications
-
Abstract
A bypass blower motor assembly having a motor section 10 and a blower section 11 separated by an end bracket 20 which has through openings. The openings are sealed by a diffuser plate 22 using a labyrinth seal and two O-rings 41, 42.
Description
FIELD OF THE INVENTION
This invention relates to blower motors and in particular, to a blower motor for use in a bypass or wet-type vacuum cleaner application.
BACKGROUND OF THE INVENTION
Blower motors in bypass vacuum cleaners have an impeller which moves air from an inlet to an outlet of an impeller housing fitted to the motor without passing through the motor itself. This construction allows the vacuum cleaner to suck up liquids as well as dust and dirt without damaging the electric motor.
The impeller is mounted on a shaft of the motor. The shaft is journalled in a bearing where it passes through an end bracket of the motor housing which also acts as a divider between the motor and the impeller. The bearing is sealed and an additional seal between the shaft and the end bracket may be provided to prevent air leakage from the impeller housing into the motor proper through the bearing. The fan end bracket separates the motor from the impeller housing and separates the motor from the working air flow of the impeller. One problem is that the fan end bracket has an axial extending annular projection to connect with the stator of the motor. A fan providing air flow for cooling the motor is mounted on the shaft adjacent the fan end bracket. This requires apertures in the annular projection to avoid the use of expensive side core moulding dies. These apertures are provided by axial holes which extend through the outer planar surface of the fan end bracket into the annular projection,. These holes in the end bracket need to be closed in order to seal the impeller chamber from the motor. This has been done conveniently by a diffuser plate. The diffuser plate provides guides for guiding the working air from the impeller to outlet openings in the impeller housing. The diffuser plate has a planar portion which lies over the fan end bracket and covers the openings in the end bracket. This has proved successful in low pressure blowers, but modern bypass blower motors run at a higher speed with more efficient impellers creating a higher pressure environment inside the impeller chamber adjacent the diffuser and end bracket. The high air pressure inside the impeller chamber causes leaking of air between the diffuser plate and the end bracket.
SUMMARY OF THE INVENTION
Accordingly, there is a need for an effective yet simple air tight seal between the end bracket and the diffuser plate. This is achieved by the present invention by the use of labyrinth seals, O-ring seals or a combination thereof between the end bracket and the diffuser plate.
Accordingly, the present invention provides a bypass blower motor assembly comprising: a motor including a shaft and a fan end bracket supporting a bearing for the shaft; a diffuser plate fitted to the fan end bracket; an impeller fixed to the shaft for rotation therewith; and an impeller housing fixed to the fan end bracket and accommodating the impeller and diffuser plate, wherein the impeller housing has an inlet and a plurality of outlet openings, the impeller being operated to create an air flow from the inlet to the outlet openings and the diffuser plate having vanes for guiding the air flow from the impeller to the outlet openings, the fan end bracket has a number of openings which are seated by the diffuser plate.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
FIG. 1
is a part sectional view of a blower motor assembly incorporating an end bracket and diffuser plate arrangement according to the present invention;
FIG. 2
is a perspective view from above of an end bracket as used in the assembly of
FIG. 1
;
FIG. 3
is a perspective view from below of the end bracket of
FIG. 2
;
FIG. 4
is a perspective view from above of a diffuser plate as used in the assembly of
FIG. 1
;
FIG. 5
is a perspective view from below of the diffuser plate of
FIG. 4
; and
FIG. 6
is a schematic sectional view of a part of the assembly of
FIG. 1
showing how the end bracket and the diffuser plate fit together.
DETAILED DESCRIPTION OF THE INVENTION
A bypass blower motor assembly as used, for example, in a wet and dry vacuum cleaner is shown in partial section in FIG.
1
. The motor assembly can be divided into a motor section and a blower section. The motor section comprises a universal motor
10
. The blower section
11
comprises a high speed impeller
12
of the centrifugal fan type located within an impeller chamber
13
defined in part by an impeller housing
14
.
As the universal motor and the blower are of known construction, details of their construction and operation will not be described in detail here except as required to explain the invention.
The motor
10
has a shaft
15
which is supported in bearings
16
and
17
. Bearing
16
, located adjacent the impeller chamber
13
, is housed in a boss
18
formed in a fan end bracket
20
. Oil seal
19
seals the shaft opening in the boss
18
. Bracket
20
has a generally radially extending flange
21
to which the impeller housing
14
is secured. The impeller housing
14
has an inlet
23
in its lower surface and a plurality of louvered outlet openings
24
around its side. Rotation of the impeller
12
causes air to be drawn in through the inlet
23
and expelled through the outlets
24
. A diffuser plate
22
has a plurality of vanes for directing the air from the impeller
12
to the outlet openings
24
. The end bracket
20
is mounted directly to the stator core
25
of the motor
10
to accurately locate the bearing
16
. The stator core
25
sits on an annular axial projection
26
of the bracket
20
and is clamped between bracket
20
and input end bracket
27
by bolts
28
. The motor
10
has a fan
29
located next to bearing
16
for generating a flow of air for cooling the motor. The fan
29
draws air axially down over the motor and through the stator core
25
and then radially outwardly through windows
30
in the annular projection
26
of the end bracket
20
.
The fan end bracket
20
is an injection moulded part of thermosetting plastic material. The windows
30
in the annular projection
26
are formed by moulding axially extending apertures
31
in the lower face of the end bracket
20
as shown in FIG.
3
. The diffuser plate
22
is disposed on the lower surface of the bracket
20
. The diffuser plate
22
has a planar central portion
32
with a central opening
33
for locating the boss
18
of the end bracket
20
. Around its periphery is a plurality of vanes
34
for directing the working air from the impeller upward to and outward through outlet openings
24
in the impeller housing
14
. Each vane
34
has two guiding surfaces, one for guiding the air upward and another for guiding the air outwards.
The diffuser plate
22
also has a number of axial projections
35
which correspond in shape to the apertures
31
in the bracket
20
so that when fitted together as shown in
FIG. 6
, the projections
35
close the apertures
31
in the planar portion of the bracket
20
and do not extend into the annular projection
26
thus leaving open the windows
30
in the annular projection
26
for the passage of the cooling air. However, the projections
35
do not fully seal the apertures
31
against the high air pressure environment of the inside of the impeller chamber
13
.
To seal the joint between the diffuser plate
22
and the end bracket
20
, a labyrinth type seal arrangement is provided. Referring to
FIG. 3
where the underside of the bracket
20
is shown, we can see that the underside of the bracket
20
has an outer annular wall
36
extending axially, an inner circular wall
37
just radially outward of the four openings
31
and a second annular wall
38
of lower height located just radially outside of the circular wall
37
, thereby creating a groove
39
at the base of the circular wall. There is another groove
40
in the bracket
20
about the base of the boss
18
where it meets the lower surface of the bracket. O-ring seals
41
,
42
are installed in the two grooves
39
,
40
(shown in FIG.
1
).
Turning now to
FIG. 4
, the upper surface of the diffuser plate
22
has an annular wall
43
enclosing the fan bracket projections
31
and a second radially outer wall
44
forming the periphery of the plate from which the vanes
34
extend. The walls
43
,
44
mate with the walls
36
,
37
,
38
of the bracket
20
to form a labyrinth seal. Also the inner wall
43
of the diffuser plate
22
compresses the O-ring sea
41
in the outer groove
39
to perfect the outer seal. The inner seal is provided by the inner O-ring seal
42
being compressed by the diffuser plate
22
directly into the inner groove
40
in the bracket
20
.
The labyrinth seal is designed to provide a flow path between the bracket
20
and the diffuser plate
22
which has such a high resistance that air does not flow. Should air flow, the path is too difficult for moisture and debris to be carried into the motor section. However, the O-ring seals
41
,
42
provide additional sealing preventing leakage of air from the blower section
11
into the motor section
10
through the interface between the fan end bracket
20
and diffuser plate
22
. The diffuser plate
22
is fixed to the end bracket
20
by four screws
45
which screw into the end bracket
20
. Each screw
45
has a flanged head and an O-ring seal is nipped between the flanged head and the diffuser plate to prevent air leakage through the mounting screw holes (not shown).
The embodiment described above is given by way of example only and various modifications will be apparent to persons skilled in the art without departing from the scope of the invention as defined in the appended claims.
Claims
- 1. A bypass blower motor assembly comprises:a motor including a shaft and a fan end bracket supporting a bearing for the shaft; a diffuser plate fitted to the fan end bracket; an impeller fixed to the shaft for rotation therewith; and an impeller housing fixed to the fan end bracket and accommodating the impeller and diffuser plate, wherein the impeller housing has an inlet and a plurality of outlet openings, the impeller being operable to create an air flow from the inlet to the outlet openings and the diffuser plate having vanes for guiding the air flow from the impeller to the outlet openings, and the fan end bracket has a number of openings which are sealed by the diffuser plate.
- 2. The assembly of claim 1 wherein the end bracket and the diffuser plate provide a labyrinth seal arrangement to seal the openings in the end bracket.
- 3. The assembly of claim 1 wherein at least one O-ring seal is nipped between the end bracket and the diffuser plate to seal the openings in the end bracket.
- 4. The assembly of claim 3 wherein the O-ring is pressed into a groove in the end bracket or the diffuser plate by a projection formed on the other of the diffuser plate or end bracket as appropriate.
- 5. The assembly of claim 4 wherein one of the O-ring seals is located radially outward of the openings and the other one of the O-ring seals is located radially inward of the openings.
- 6. The assembly of claim 5 wherein the inner O-ring seal is located in a groove adjacent to a bearing boss formed in the end bracket.
- 7. The assembly of claim 6 wherein the diffuser plate is fixed to the end bracket by screws and the head of each screw is sealed to the diffuser plate.
- 8. The assembly of claim 7 wherein the head of each screw is sealed to the diffuser plate by an O-ring seal.
- 9. The assembly of claim 1 wherein two O-ring seals located in respective grooves in the end bracket or diffuser plate are pressed into the grooves by the diffuser plate or end bracket as appropriate to seal the openings.
- 10. The assembly of claim 1 wherein the diffuser plate is fixed to the end bracket by screws and the head of each screw is sealed to the diffuser plate.
Priority Claims (1)
Number |
Date |
Country |
Kind |
0202839 |
Feb 2002 |
GB |
|
US Referenced Citations (6)
Number |
Name |
Date |
Kind |
4057370 |
Numata et al. |
Nov 1977 |
A |
4547206 |
Sovis et al. |
Oct 1985 |
A |
4679990 |
Yamaura et al. |
Jul 1987 |
A |
4767285 |
Jyoraku et al. |
Aug 1988 |
A |
5110266 |
Toyoshima et al. |
May 1992 |
A |
6309180 |
Gilliland et al. |
Oct 2001 |
B1 |
Foreign Referenced Citations (1)
Number |
Date |
Country |
1 025 792 |
Aug 2000 |
EP |