POMPE D'EAU POUR PROPULSEUR D'EMBARCATION

MARINE DRIVE WATER PUMP

Abrégé anglais

Improved Marine Drive Water Pump
Abstract
An improved water pump (16) for a marine drive
includes a base plate (22), a cup-shaped impeller
housing (30) and a shroud (52). An impeller (40)
having a plurality of flexible vanes (46) is positioned
within the impeller housing (30). Water enters the
pump (16) from a water inlet (28) in the base plate (22)
and is forced by the rotating impeller (40) through a
water outlet (38) to the marine drive. The impeller
housing (30) and shroud (52) are formed of stamped
metal parts and the impeller (40) includes long,
flexible vanes (46).

Revendications

The embodiments of the invention in which
an exclusive property or privilege is claimed are
defined as follows:
1. In a marine drive having a water cooled
engine rotating a drive shaft and having a cooling
water intake, the improved water pump comprising:
a) a base plate mounted in said marine drive,
said base plate having an eccentrically positioned
drive shaft opening and a water inlet opening into the
cooling water intake,
b) a cup-shaped impeller housing formed
of deformed sheet metal having an end wall and a
peripheral wall, said end wall having an eccentrically
positioned drive shaft opening and a water outlet,
c) an impeller positioned in said impeller
housing for propelling water received at said water
inlet out said water outlet, said impeller having a
central hub coupled to the drive shaft and a plurality
of flexible impeller vanes extending outwardly from
said central hub into contact with the peripheral wall
of said impeller housing, and
d) a shroud formed of deformed sheet metal
fitting over said impeller housing to embrace the end
wall and peripheral wall of said housing, said shroud
being secured to said base plate, said shroud forming
an arcuate collecting chamber between the shroud
and the impeller housing to connect said outlet with
a water discharge opening for said pump angularly
displaced from said water outlet about the axis of
the drive shaft.
2. The improved water pump according to
Claim 1 wherein said shroud abuts said base plate and
wherein said pump includes sealing means between said
shroud and said base plate.

3. The improved water pump according to
Claim 1 wherein said base plate, impeller housing,
and shroud are formed of stainless steel.
4. The improved water pump according to
Claim 3 wherein said impeller housing has a work
hardened peripheral wall.
5. The improved water pump according to
Claim 1 wherein said impeller vanes are dimensioned
in length and width to create low flexural stresses
in said impeller vanes, said length dimension being
radial with respect to the drive shaft and said
width dimension being normal to said length dimension
and to the drive shaft; the ratio of the vane length
to width being greater than 3:1 and the ratio of the
inside diameter of the impeller housing to the outside
diameter of the impeller hub is greater than 1.9:1.

Description

6472g
Descri~ on
Improved llarine Drive l,ater Pump
Technical Field
~larine drives havinp water cooled enaines utilize
a water pump mounted over the drive shaft and internal
to the drive shaft housing to provide engine cooling.
Background Art
One prior water pump used for cooling an outboard
engine utilized a cast metal housing. The cast metal
housina requires machining and is costly to manufacture
Also the life of a cast brass or cast aluminum water
pump is relatively low where the water contains sand
and silt ~hich will cause internal wear on the moving
parts.
Another prior water pump is formed of a molded
plastic housing. A metal liner is used within the
plastic housing to provide abrasion resistance l~ithout -
the metal liner the plastic will wear through resulting
in a water pump failure~ A water pump failure may also
result in engine failure.
Disclosure of Invention
The present invention provides an improved marine
drive water pump that is simply and economically formed
through the use of stamped metal parts. The parts are
2~ used without machining.
The improved water pUmD of the present invention
includes:
a base Dlate mounted in the r,larine dr;ve
the base plate having an eccentrically positioned drive
shaft opening and a water inlet opening into the
coolina water intake;
a cup-shaped impeller housing formed of
deformed sheet metal having an end wall and a peripheral
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wall, the end wal:l havi.ncJ an ecce~ntrLccllly posltioned dr:ive
shaft opening and a water outlet;
an impeller posi-tionecl in the lmpeller housing for
propelling water received at the water inlet ou-t -the water
outlet, the impeller having a central portion coupled to the
drive shaft and a plurality of flexible impeller vanes
extending outwardly from the central portion into con-tact with
the peripheral wall oE the impeller housing; and
a shroud formed of deformed sheet metal fi-t-ting over
the impeller housing to embrace the end wall and peripheral
wall of the housing, the shroud being secured to the base plate
and forming an arcuate collecting chamber between the shroud
and the impeller housing to connect the outlet with a water
discharge opening for the pump angularly displaced from the
water outlet about the axis of the drive shaft.
The improved water pump of the invention provides a
water pump which has an increased service life and provides a
superior silt resistance and dry running capability. The use
of a metal stamping provides work hardening of the wear
surfaces providing silt resistance and long flexible vanes on
the impeller reduces wear on the impeller housing and results
in longer impeller life.
The improved water pump of the invention provides in
a single water pump all of the features necessary for a marine
drive. These features are abrasion resistance, dry run
survivability, reduced pressure loss with time, long flex life,
excellent corrosion resistance, relatively low cost and
excellent long-term adhesion of impeller rubber to its non-
metal insert. In the improved water pump the long flexible
vanes provide a low radial pressure thereby resulting in a
reduced wear on the impeller housing, a longer flex life for
the vanes, reduced pressure loss with respect to time and low
friction. The low friction reduces the heat build up in the
vanes and thereby permits better dry running of the water pump.
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Brief Description_of Drawincls
Figure 1 is a partially broken a~ay side view of
an outboard engine illustrating the water pump of the
present invention.
Figure 2 is a cross-sectional view of the ~later
pump shown in Figure 1~
Figure 3 is an exploded view showing the components
of the water pump shown in Figure 1 appearing with Figure 1.
Figure 4 is a plan view of the impeller of the
water pump shown in Figure 1.
Figure 5 is a view from beneath showing the
impeller in the impeller housing.
Best Mode for Carryinn Out the Invention
The ~arine drive is shown as an outboard engine 10
in Figure 1 The outboard engine 10 includes a liquid
cooled .power head 12 that powers the drive shaft 14
The en~ine is cooled by water supPlied by a pump 16.
The propulsion unit 18 of the outboard engine 10 contains
a water intake 20 that is within water when the propul-
sion unit 18 is in the onerating position. The waterpumn 16 also may be mounted in the outboard engine 10
so that it is below the ~/ater line when the propulsion
unit 18 is submerged
The water pump 16 includes a base plate 22 that
is mounted in the outboard engine 10 above the water
intake conduit 24 and within the oear case housing
The base plate 22 is preferably formed of stainless
steel sheet. The base plate 22 has an eccentrically
positioned drive shaft opening 26. The base plate 22
includes a water inlet 28 snaced from the opening 26
and communicating with the water intake conduit 24.
A cup-shaped impeller housing 30 is positioned on
the base plate 22 to connect ~Jith the water ;nlet 28.
In the preferred embodiment the impeller housing 30 is
formed from a stainless steel sheet to- lend econo~y and
corrosion resistance in the manufacture of the pump 1
and to provide hardening of desired areas of the
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resulting housing. The impeller housing 30 has a
peripheral wall 32. An end wall 34 of the impeller
housing 30 also contains an eccentrically posit.ioned
drive shaft opening 36. The wall 34 also includes ~
water outlet 38 spaced from the opening 36 and about
oppositely displaced as shown in the figures from the
water inlet 28 after the pump 16 is assembled.
The impeller 40 is positioned in the impeller
housing 30. The impeller 40 is formed of a flexible
material such as synthetic rubber compounded for
temperature resistance. The preferred flexible material
is nitrile elastomer. The impeller 40 includes a hub
42. The hub 42 is partly formed of fiber reinforced
plastic to increase the corrosion resistance of the
~ater pump 16 by avoiding a metal-to-metal contact
between the impeller 40 and the drive shaft 14. The
hub 42 is keyed to the drive shaft 14 by a key 44. A
plurality of long, flexible impeller vanes 46 extend
from the hub 42 of the impeller 40. In the preferr~d
embodiment, as shown in Figure 4, six such vanes are
provided. The sealing rings 48 and 50 on either side
of the hub 42 serve to seal the impeller housing 30 when
the impeller 40 is located in the impeller housing 30
as shown in Figure 2. The length and flexural properties
of the vanes 46 and the inside diameter of the impeller
housing 30 are selected so that a low radial pressure
is exerted by each vane 46 on the peripheral wall 32
and low flexural stresses result in vanes 46. In the
preferred embodiment the vane length is about 0.64
inches, the vane width at the hub 42 is about 0.2 inches
and the ratio of the vane length to width is about 3.2:1.
The hub outside diameter is about 1.04 inches and the
inside diameter of the impeller housing 30 is about 2
inches and the ratio of the inside diameter of the
impeller housing 30 to the outside diameter of the
impeller hub 42 is greater than 1.9:1. The height
o~ the vane parallel to drive shaft 41 is adjusted to

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obtain the desired capacity or volume flow of the water
pump. In an alternative embodiment the vane length is
about .85 inches, the vane width at the hub 42 is
about 0.26 inches and the ratio of the vane length to
width is about 3~3:1. The hub outside diameter is
about 1.2 inches and the inside diameter of the impeller
housing 30 is about 2.5 inches and the ratio of the
hub outside diameter to the impeller housing inside
diameter is about 2.1:1.
In order to obtain the best flexure life of
the vanes 46 it is required that the ratio of the vane
length to width is equal to or greater than 3:1 and
that the ratio of the inside diameter of the impeller
housing 30 to the outside diameter of the impeller hub
42 is greater than 1.9:1. Since the impeller 40 is
positioned in the impeller housing 30 eccentrically
with the inside diameter of the housing 30 as previously
described and as shown in Fig. 5 the outside diameter
of the impeller 40 is larger than the inside diameter
of the impeller housing 30. The ratio of the outside
diameter of the impeller 40 to the inside diameter of
the impeller housing 30 is in the range of 1.10:1 to
1.16:1. This is necessary to provide sealin~ between
the end of the vanes and the peripheral wall 32.
It is also preferred that the tip width of the
vanes be a minimum. In the preferred embodiment the
tip width is about 0.12 inches and in the alternative
embodiment the tip width i9 about 0.15 inches. The
tip width is obtained by tapering the vane from its
width at the hub to its extreme width at an included
angle of about 8 to 9 degrees.
A shroud 52 fits over the impeller housing 30.
In the preferred embodiment the shroud 52 is formed
from a stainless steel sheet. The shroud 52 includes
a flange 54 which contacts the base plate 22. The
shroud 52 and the base plate 22 are secured to the
~pulsion unit l~ by the bolts 56. The bolts 56 are
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also ~ormed of stainless steel to reduce corrosion.
Non-metallic sleeves 58 are positioned over the bolts
56 and between the flange 54 to improve corrosion
resistance. The shroud 52 has a peripheral wall 60
press-fitted with the peripheral wall 32 of the im-
peller housing 30. An 0-ring 62 at the edge of the wall
60 of the impeller housing 30 seals the base plate 22
from the impeller housing 30 and a separate gasket
between the base plate 22 and the shroud 52 seals the
base plate 22 from the outboard engine 10. The transi-
tion between the wall 60 and the flange 54 may be
suitably formed to accommodate an 0-ring 62. The
shroud 52 has an end wall 64 containing an eccentric
opening 66 for insçrting the drive shaft 14. A
rotary slinger 68 is positioned over the drive shaft
14 on top of the water pump 16 to prevent entry of
dirt and sand. When press-fitted the end wall 60
of the impeller housing 30 and the end wall 64 of
the shroud 52 form a collecting chamber in the form of
anarcuate passage 70 that connects the water outlet 38
of the impeller housing 30 with the water discharge
pipe 72 through the connector 74. A water discharge
pipe 72 connects the cooling water from the water pump
16 to the heat producing portions of the outboard engine
10 for cooling.
In operation the i~peller housing 30 receives
water through the water inlet 28 in the base plate 22.
As shown in Figure 5 the vanes 46 are sequentially
flexed against the wall 32 of the impeller housing 30
by ~h~ ê~ O rotation of the drive shaft 14 first
a~ lhQ~e~ng ~xtant and then to a decreasing extent
~u~ @a~h ~Qt~tl~n of the impeller 40. The flexing
~ ~h~ ~a~- 46 and the resulting reduction in the
volume between them and the peripheral wall 32 of the
impeller housing 30 forces the water in the impeller
housing 30 out water outlet 38, then through the passage
70 and into the water discharge pipe 72.
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