EP1242744A1

EP1242744A1 - Pump housing

Info

Publication number: EP1242744A1
Application number: EP00982243A
Authority: EP
Inventors: Todd W. Leonhard; Shawn Leu
Original assignee: Thomas Industries Inc
Current assignee: Thomas Industries Inc
Priority date: 1999-11-29
Filing date: 2000-11-28
Publication date: 2002-09-25
Anticipated expiration: 2020-11-28
Also published as: DE60027202T2; AU1930001A; EP1242744B1; DE60027202D1; CN1246595C; JP2003515061A; WO2001038743A1; CA2392909C; MXPA02005296A; CA2392909A1; JP4052628B2; CN1402815A

Abstract

A pump housing (14, 16) has a fan guard (40) secured to the end of the housing by four crescent-shaped tabs (60) fitting into four crescent-shaped cast-in recesses (66) of the housing (14, 16) and ears (68) of the tabs (60) fitting into cast-in holes (70) in the housing (14, 16). The ears (68) and holes (70) on opposite sides of the housing (14, 16) are aligned along a common axis (80, 82). The ears (68) are tapered at their leading ends (90) and squared off at their trailing ends (92), and the guard (40) has a radial projection (56) that fits into an opening in the housing (14, 16).

Description

PUMP HOUSING

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 60/167,839 filed November 29, 1999.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to pumps such as compressors and vacuum pumps, and in

particular to a housing for a pump.

Discussion of the Prior Art

Reciprocating piston or diaphragm pumps typically have a metal housing, for

example, a cast aluminum alloy, in which bearings are mounted which journal the shaft

which drives the pump. A metal housing is needed, particularly for larger pumps, to

withstand the forces of driving the piston or diaphragm and containing the pressure

exerted in the compression chamber of the pump.

A rotary electric motor is usually used to drive these pumps and the motor

requires cooling. In one such pump, the motor is provided between two housings, each

of which is separate from the other and houses one compression chamber. The shaft of

the motor is a through shaft so that each end of the shaft mounts one of the pistons or

diaphragms that work to vary the volume of the compression chamber in the housing at

the corresponding end of the shaft. Further out from where the piston or diaphragm is mounted, a rotary fan blade is mounted to each end of the shaft to draw a flow of cooling

air into the housing at that end and blow it onto the rotor and stator coils of the motor.

For cooling efficiency, it is desirable to make the part of the housing in which the

rotary fan blade is mounted circular and just slightly larger than the diameter of the fan

blade. The clearance between the tips of the fan blades and the interior housing surface

should be as small as possible because, if not, the air drawn into the housing by the fan

blades will simply blow back out past the tips of the blade, and not be directed over the

coils of the motor. For applications in which the pump is contained inside of a separate

enclosure, it may be permissible to leave the end of the housing at which the fan blade

is mounted open. However, if the pump is going to be exposed or sold as a stand-alone

product, the end of the housing must be closed with a cover which permits air to be

drawn into the housing, but prevents the insertion of larger objects or fingers. This cover,

typically called a fan guard, should not deleteriously affect the operation of the fan nor

add to the lateral size or detract from the appearance of the fan.

SUMMARY OF THE INVENTION

The invention provides a fan guard which easily attaches to the housing, without

requiring any special machining of the housing, does not increase the internal clearance

for the fan and does not add to the lateral size of the housing or detract from its

appearance. The fan guard is perforated so as to permit the inflow of air to the housing

past it, and has peripheral tabs which extend into the housing in a direction parallel to the

axis of the shaft. The tabs have a crescent-shaped profile, and similarly shaped recesses

are formed in the housing. The crescent-shaped recesses of the housing have holes

formed in them. Each tab of the fan guard has an ear which snaps into the hole in the

corresponding recess to hold the fan guard in place over the end of the housing. In a preferred form, the recesses and holes are cast-in features of the housing. The

holes which are formed in the recesses preferably have a horizontal axis to permit them

to be formed during the casting process, since inserts in the die move in this direction,

which is perpendicular to the parting line of the casting. As a consequence, the axes of

all the holes in the recesses are parallel to one another. Each ear also has an axis, which

is the major direction it extends from the tab, and this axis of the ear generally

corresponds to the axis of the hole, so that the ear axis is parallel to the hole axis when

the ear is received in the hole. A ramped surface is preferably provided on the distal end

of the ear, to flex the tab inwardly upon insertion of the fan guard in the end of the

housing, and the proximate end of the ear is squared off so that the ear snaps into the hole

and the near side of the hole is caught by the proximal end of the ear when the snap-in

fan guard tabs are inserted into the end of the housing.

The crescent-shaped tabs, which are also referred to herein as D-shaped, are

preferably somewhat smaller than the similarly shaped recesses in the housing so that the

inward surface of the tabs approximates a continuation of the inner surface of the housing

so as not to interfere with the fan blades or require an excessive clearance between the

tips of the fan blades and the interior of the housing. It is preferred that the inner surface

of the tab be somewhat recessed within the crescent-shaped recess so that if the ear is not

fully engaged in the hole, or if the fan guard is removed with the fan turning, the tabs do

not flex so far inwardly as to interfere with the tips of the blade.

Any number of tabs and corresponding recesses around the periphery of the crank

case portion of the housing may be provided. In a preferred form, four tabs and

corresponding recesses are provided. The tabs and recesses are provided with two on

each side of the housing and the two on each side spaced as far apart as possible, with one toward the top of the crank case portion and the other toward the bottom of the crank case

portion on each side. Spacing the holes apart vertically helps provide a secure fixation.

The fan guard will generally be round, but it is desirable to provide at least one

feature which extends radially from the fan guard or otherwise serves to position the fan

guard angularly in the proper location relative to the housing. This feature may fit into

a similarly shaped opening in the compression chamber portion of the housing without

adding to the width or height of the compressor.

It is also noted that if the ears and holes have their axes horizontal, and the

housing recesses are arranged symmetrically on opposite sides of a vertical axis, the holes

and ears on opposite sides of the housing at the top of the housing will be along one

horizontal axis and at the bottom of the housing will be along a different horizontal axis.

Thus, the tabs at the top press against the housing opposite to one another and the tabs

at the bottom press against the housing opposite to one another to hold the fan guard in

position.

The foregoing and other objects and advantages of the invention will appear in

the detailed description which follows. In the description, reference is made to the

accompanying drawings which illustrate a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of a pump incorporating the invention;

Fig. 2 is a view like Fig. 1, but with the fan guards exploded off of the pump

housings;

Fig.3 is a sectional view with its plane radial to the shaft of the pump and through

the ears on the tabs of the fan guard with the fan guard assembled to the housing; Fig.4 is a detail view from the same plane as Fig. 3 of a single one of the tabs and

recesses with the ear received in the hole; and

Fig.5 is a longitudinal cross-sectional view of one of the tabs received in a recess

with the ear engaged in the hole. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Fig. 1 illustrates a pump 10 of the invention having a motor 12 with a housing 14

at one end and a housing 16 at the other. The housings 14 and 16 are cast of aluminum

alloy and are identical. A monolithic head 18, which includes head members 20 and 22

and connecting tubes 24 and 26 in a single casting, is bolted to the housings 14 and 16

above the respective compression chamber portions 34 and 36 of the respective housings

14 and 16 to help hold the housings 14 and 16 together and maintain their angular

position with respect to each other.

The pump 10 also includes fan guards 40, one at each end, which are identical to

one another. Referring to Fig. 2, the motor 12 has a shaft 42 which extends through it

and into both housings 14 and 16, nearly to the end of each respective housing. Each end

of the shaft 42 mounts a rotary fan blade 44 which is rotated by the shaft 42 in a direction

so as to draw air into each respective housing 14 and 16 and direct it over the coils of the

motor 12. The housing of the motor 12 is provided with holes to provide for the exhaust

of cooling air and additional ventilation slots adjacent to the motor may be provided in

the housings 14 and 16. The housings 14 and 16 mount bearings (bearings not shown)

which journal the shaft 42. The housings 14 and 16 also have openings in them which

provide for the axial through-flow of air so that air moved by the fan blades 44 reaches

the coils of the motor 12. Each fan guard 40 is perforated, having radial spokes with spaced circular ribs

running between them to provide for the inlet of cooling air past the guard 40. Each

guard 40 has a rim 50 which on its inner side defines a groove 52 in which a lip 54 of

the adjacent housing 14, 16 is received to help locate the fan guard 40 radially relative

to the housing.

A projection 56 extends radially from the rim 50 and fits into opening 58 which

is formed in the compression chamber portion 34 or 36 of each housing 14 or 16. The

projection 56 helps locate the fan guard 40 angularly relative to the housing 14 or 16 to

which it is assembled, and also provides a nameplate. The fan guard 40 is made of a

suitable resilient plastic resin, such as a polyester polymer.

Each guard 40 has four tabs 60, each in a different quadrant, which extend parallel

to the shaft 42 into the end of the respective crank case portion 62 or 64 of the

corresponding housing 14 or 16. As best shown in Fig. 4, each tab 60 is D- or crescent-

shaped generally and fits into a similarly shaped, but slightly larger recess 66 which is

formed in the respective housing 14 or 16 at a corresponding angular location and also

runs parallel to the shaft 42. Each tab 60 has an ear 68 which snaps into a hole 70 formed

in the recess 66. The recess 66 and hole 70 are both features which can readily be cast

in features by persons of ordinary skill in the art. When the tab 60 is received in the

recess 66 and the ear 68 is engaged in the hole 70, the inner surface 72 of the tab 60 is

slightly recessed from the circular surface 74 of the housing, which circular surface 74

is only slightly spaced from the tips of the fan blade 44. The surface 72 is so recessed

so that if the guard 40 is removed from the housing with the fan running, the tab 60 will

not be moved so far inwardly as to interfere with the rotating fan blade. In addition, since the tab 60 is recessed from the surface 74, the tab 60 does not increase the required

amount of clearance between the tips of the fan blade and housing.

As illustrated in Fig. 3, there are two tabs 60 and corresponding recesses 66 in the

upper portion of the crank case and two in the lower portion. The two in the upper

portion are both aligned along a single horizontal line 80 and in the lower portion are

aligned along horizontal line 82. Although the recesses 66 and arcuate surfaces of the

tabs 60 are symmetrical about lines which are radial to the shaft 42 along lines 84 and 86,

the ears 68 and holes 70 are not, being aligned along the horizontal lines 80 and 82,

which are perpendicular to the major parting line of the housing 14, 16 casting.

As best shown in Fig. 5, each tab 60 has a ramped lead-in, or distal, surface 90

which serves to flex the tab 60 inwardly when the guard is inserted in the housing. Each

ear 68 also has a proximal surface 92 which is at a right angle or nearly right angle to

outer side 94 of the ear 68 so as to provide for a snap-in connection of the ear 68 in the

hole 70.

A preferred embodiment of the invention has been described in considerable

detail. Many modifications and variations to the embodiment described will be apparent

to persons skilled in the art, so the invention should not be limited to the embodiment

described.

Claims

I Claim:

1. A pump housing having a generally cylindrical open end with an axial fan

propeller mounted on a shaft in said open end to draw air into said open end from outside

of said housing, said open end being covered by a perforated fan guard which permits air

drawn by said fan to pass by it, characterized in that said fan guard has peripheral

angularly spaced tabs which extend into the open end of the housing in a direction

parallel to the axis of the shaft, each said tab having a crescent-shaped profile and an ear

protruding from an outer surface of said tab, and wherein similarly shaped crescent-

shaped recesses are formed in the housing to receive the tabs with a curved inner surface

of the recess against a similarly curved outer surface of the tab, and holes are formed in

said housing which open into said recesses, wherein the ear of each tab snaps into the

hole in the corresponding recess to hold the fan guard in place over the end of the

housing.

2. A pump housing as in claim 1 , wherein the recesses and holes are cast-in features

of the housing.

3. A pump housing as in claim 2, wherein the holes which are formed in the recesses

each have a hole axis which is normal to a plane which includes the shaft axis and an axis

of a cylinder of the pump.

4. A pump housing as in claim 3 , wherein each ear extends from the corresponding

tab in a direction which is parallel to the direction of the hole axes.

5. A pump housing as in claim 1 , wherein a ramped surface is provided on a distal

end of the ear so as to flex the tab inwardly upon insertion of the tabs in the end of the

housing.

6. A pump housing as in claim 5, wherein the ear has a proximal end opposite from

the distal end which is squared off so that the ear snaps into the hole and the near side of

the hole is caught by the proximal end of the ear when the tabs are inserted into the end

of the housing.

7. A pump housing as in claim 1 , wherein the tabs are smaller than the recesses in

the housing so that the inward surfaces of the tabs approximate a continuation of the

inner surface of the housing so as not to interfere with the fan blades or require an

excessive clearance between the tips of the fan blades and the interior of the housing.

8. A pump housing as in claim 7, wherein the inward surfaces of the tabs are

recessed within the recesses in which they are received so that if the ear is not fully

engaged in the hole, or if the fan guard is removed with the fan turning, the tabs do not

flex so far inwardly as to interfere with the tips of the fan propeller.

9. A pump housing as in claim 1 , wherein four tabs and corresponding recesses are

provided.

10. A pump housing as in claim 9, wherein the four tabs and recesses are provided

with two on each side of the housing, with one tab and corresponding recess in each of

four equiangular quadrants of the housing.

11. A pump housing as in claim 10, wherein the four tabs and recesses are arranged

symmetrically on opposite sides of the housing, the holes and ears on opposite sides of

the housing at the top of the housing being aligned along one axis and at the bottom of

the housing being aligned along a different axis.

12. A pump housing as in claim 1 , wherein the fan guard is generally round but with

at least one feature which extends radially from the fan guard and fits into a corresponding opening of the housing to position the fan guard angularly relative to the housing.