High speed whirlpool pump

A pump for Whirlpool and Spa applications has a series wound universal motor which is directly coupled to a centrifugal impeller for operation in the range of 4000 to 9000 RPM. Variable speed of the pump is easily accomplished with a universal motor by varying the voltage to the motor.

BACKGROUND OF THE INVENTION 
This invention relates to high speed pumps, and more particularly to high 
speed pumps for Whirlpool and Spa applications. 
Other similar devices primarily fall into five categories: 
a. Close coupled end suction (non-self draining), low speed pump on single 
speed, A.C. induction motor. 
b. Close coupled end suction, self-draining, low speed pump on single 
speed, A.C. induction motor. 
C. Close coupled end suction (non-self draining), low speed pump on two 
speed, A.C. induction motor. 
d. Close coupled end suction, self-draining, low speed pump on variable 
speed, variable frequency induction motor. 
e. Belt driven, low speed submersible pump powered by high speed series 
wound universal motor (portable Whirlpool units only). 
All of the above categories of Whirlpool pumps, provide flow and pressure 
to the liquid to be circulated in the normal manner consistent with single 
stage centrifugal, Kinetic pumps, of radial vane, closed impeller 
construction. Substantially all of the Whirlpool pumps are driven by 
various types of induction motors, as is the case with most electric motor 
driven centrifugal pumps. 
The biggest shortcoming with the above mentioned current devices is the 
inherent relative high cost of the motor. The size and, therefore, cost of 
the motor is inversely related to the motor speed. The higher the speed 
the smaller the size and the lower the cost. The maximum motor speed on 
normal household A.C. current is 3600 RPM, based on an A.C. induction 
motor, with the minimum number (two) of motor poles and 60 cycles per 
second current frequency in the USA. Devices have been developed for 
induction type A.C. motors which can vary the cycle frequency (and 
therefore motor speed) up or down, however, this does not reduce, but 
rather increases the complexity and cost of the motor plus controls 
package. 
Even when the motor speed (and therefore pump speed) is increased by means 
of a variable frequency device, there is a limit to the speed of a 
conventional centrifugal pump in Whirlpool or Spa applications due to 
cavitation in the inlet of the impeller vanes. This is why belt-driven 
submersible pumps powered by high speed universal motors are stepped down 
to about 3600 RPM today. Further, conventional universal motors are 
inherently noisy and must normally operate at very high speeds (over 
10,000 RPM) to provide sufficient cooling for the power levels required 
with a fixed installation Whirlpool pump. 
Additionally, the following patents were developed in searching the various 
features of the invention: 
______________________________________ 
Patent No. Inventor 
______________________________________ 
4,661,041 Hessler 
3,384,022 Oshima 
4,019,829 Knopfel et al. 
4,449,889 Balje 
4,523,900 Frey 
4,642,023 Dunn 
4,213,742 Henshaw 
4,389,159 Sarvanne 
4,518,311 Dernedde et al. 
3,516,757 Baumann 
4,126,360 Miller et al. 
4,286,919 Yamaguchi 
2,991,927 Quick 
4,842,481 Collins 
3,286,639 Hutton 
______________________________________ 
Accordingly, the high speed pump for Whirlpool and Spa application of the 
invention overcomes the limitations of the prior art devices. 
SUMMARY OF THE INVENTION 
An object of the invention is to provide an improved pump which operates at 
high speed. 
According to the broader aspects of this invention, a series wound 
universal motor is used to power, thru a direct drive (close coupled), a 
high speed centrifugal impeller, to speeds in the range of 4000 RPM to 
9000 RPM, for Whirlpool and Spa applications. A universal motor is cheaper 
than a single speed, two speed or variable speed induction motor, due to 
the higher speed and subsequent smaller motor size. Also, variable speed 
is easily accomplished with a universal motor by just varying only the 
voltage to the motor, and variable speed is a desirable option in the 
Whirlpool and Spa market. 
A feature of the invention is that the leading edge of the impeller vanes, 
extends forward along the axial portion of the front shroud, toward the 
incoming flow stream (impeller eye) to form a female "inducerpeller". The 
female inducerpeller portion of the impeller vane has an extensive sweep 
back angle to the incoming flow, approximately five to fifteen degrees to 
the impeller axis. Inducers (male and female) are known to improve pump 
suction performance and allow the pump to operate at high speeds without 
excessive cavitation (noise and/or damage). There are also impellers which 
extend the full impeller vanes axially into the impeller eye to form a 
male "inducerpeller" to achieve the same improved suction performance as a 
separate inducer with an impeller. The inventive inducerpeller only 
extends the portion of the vane attached to and near the front shroud into 
the impeller eye to form a female "inducerpeller". Cavitation normally 
starts where the leading edge of the impeller vane meets the front shroud. 
This achieves the required improved suction performance (for a high speed 
universal motor direct drive (in the 4000 RPM to 9000 RPM range) without 
increasing the cost or size of the pump, as would be required with a 
separate inducer, or operating the pump at slow speed. Although female 
inducerpeller vane extensions are known in the industrial pump industry, 
an inventive feature is its coupling with a universal motor driven pump 
for Whirplool and Spa applications, and particularly with molded plastic 
impellers. 
Another feature of the invention includes unique modifications to the motor 
fan to both reduce the motor noise level and increase motor cooling. The 
basic function of a motor cooling fan is to draw ambient air into the 
motor housing, thru the stator laminations, over the field coils, 
armature, commutator and brushes, while providing sufficient air currents 
to also cool the motor bearings. Fans of this type are well known to the 
motor industry, and for best cooling and noise they normally maximize the 
number of vanes on the fan to the point that additional full vanes will 
block air flow through the inlet portion of the fan. The fan according to 
the invention is more effective (quieter and better cooling) due to the 
application of splitter (short) vanes equally spaced between the normal 
full length fan blades, coupled with a reduction of the rear fan shroud 
diameter below the maximum blade outer diameter. The use of splitter vanes 
allows more blades/vanes to be used on the fan without blocking the air 
inlet to the fan. The higher number of blades/vanes reduces the pressure 
loading on the fan individual blades/vanes, which reduces the noise level, 
and increases the frequency of the motor noise which makes the noise 
easier to block. The reduction of the rear shroud reduces the blockage of 
the axial component of the air flow at the discharge of the fan, as it 
exits the motor housing vents with as little restriction as possible. The 
better cooling from this fan also allows a smaller outer fan diameter 
which further reduces the noise level. 
A further feature of this invention includes a modification to the motor 
housing stationary "peeler" tongue which is close to the outer diameter of 
the fan blades/vanes. The peeler tongue has been skewed at an angle with 
respect to the fan blades to further reduce motor/fan noise. Without the 
skewing, the valving effect of the high and low pressure sides of each fan 
vane passing close to the peeler tongue causes strong pressure pulsations, 
or noise. By skewing the peeler tongue, this causes a more gradual 
fluctuation of the fan exit pressure as the fan blades pass close to the 
tongue, thus generating less noise. 
An additional feature of this invention includes a multipurpose motor 
mounting foot which supports the motor and indirectly the pump, encloses a 
cavity in the bottom of the motor for mounting electrical control board 
while maintaining double insulation integrity and sound deadening between 
motor and motor foundation. The above functions are achieved by use of an 
elastomeric material mounting foot. Most motors have metal or hard plastic 
mounting feet with only one function. 
Yet another feature of this invention is the two step front impeller seal 
wear ring (surface) construction to reduce the recirculation leakage flow 
into the pump suction. Not only does this increase pump efficiency but it 
improves the suction performance of the pump. This coupled with the 
described inducerpeller above, permits the pump to be operated at high 
speeds. Although, two step front impeller seal wear ring (surface) 
construction is known for use with industrial pumps, an inventive feature 
is its use with universal motor driven pumps in the Whirlpool and Spa 
applications, especially when coupled with the female inducerpeller vane 
extensions previously discussed. 
A still further feature of this invention is a unique combination of 
mechanical seal components which permit dry running of the mechanical seal 
to speeds up to 18,000 RPM. This feature is achieved by using a rotating 
ceramic component on the back side of a plastic impeller, which has a 
metal band around the outer circumference. This metal band dissipates a 
sufficient amount of heat to allow the seal and impeller to survive for 
hours when run dry at these high speeds. This is even a bigger problem 
with universal motors, since they speed up when unloaded. 
Also, a feature of this invention includes a unique method of housing the 
variable speed controls, so that a separate enclosure will not be required 
for the speed control elements. This adds to the low cost of the design. 
Other variable speed control devices for Whirlpool and Spa application 
require separate enclosures. This inventive feature is achieved by adding 
an electrical compartment to the belly of the motor, covered by the motor 
mounting foot for mounting a control PC board. Another control PC board 
may be mounted in the rear of the motor on the rear motor compartment 
cover for heat dissipation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The pump apparatus of the invention will best be understood by reference to 
FIG. 1. As illustrated, the apparatus includes a suction cover 11, suction 
inlet 12, insert 13, and self-draining channel 14. A O-ring 16 is 
positioned between cover 11 and casing 18 having an outlet 19. Cover 11 
and casing 18 are mounted to universal motor housing 20 by self taping 
screws in a standard manner. The universal motor includes a stator 22 and 
an armature 24. The armature 24 includes a commutator 25, and a shaft 26 
having a threaded end 27 and a splined end 28. The commutator brushes for 
the universal motor are located in the housing 20 in a plane perpendicular 
to the cross-sectional view. 
Threaded on shaft end 27 is an inducerpeller 30 having mounted thereon a 
rubber boot 31, ceramic ring 32, and metal retaining ring 33 which form 
part of a mechanical seal. The other part of the mechanical seal includes 
a carbon seal ring 35, rubber boot 36, spring 37, and retaining cup 38. An 
O-ring 39 is positioned between cup 38 and casing 18. Inducerpeller 30 has 
two step front surfaces 40,41 which run with a clearance between the 
complementary inner surfaces 13a,13b of insert 13 to provide an impeller 
seal wear ring surface to reduce recirculation leakage flow into the pump 
suction. The inducerpeller has a vane 42 with a vane portion 42a which 
extends forward along the axial portion of the front shroud 40a, and 
sweeps back an angle of approximately 5.degree. to 15.degree. to the 
impeller axis to improve suction performance. 
A slinger 44 is mounted on shaft 26 adjacent bearing hub 46 of housing 20. 
Bearings 48, rotatably mount shaft 26 in hub 46, and bearings 50 rotatably 
mount the splined end 28 to housing bearing surface 52, and bearing 50 is 
retained on housing bearing surface 52 by means of strap 53. A fan 55 is 
spline mounted on the spline end 28 of shaft 26. 
An elastomeric motor mounting foot 60, encloses a compartment 61, in which 
may be mounted a circuit board 62 for mounting electrical components 62a,b 
for motor speed control. Back plate 65 encloses another compartment 66 in 
which may be mounted another circuit board 67 for mounting other of the 
electrical components 67a,b to control motor speed. Terminals 70,71,72 are 
used to connect leads to and from circuit boards and power source. Power 
leads (not shown) are coupled through opening 21 in housing 20 in known 
manner. Back plate 65 may be metal to facilitate heat transfer through 
fins 65a from circuit board 67 which may be the high power circuit board 
of the control requiring the most heat dissipation. 
In the preferred embodiment, cover 11, insert 13, casing 18, housing 20, 
inducerpeller 30, fan 55, and mounting foot 60 are made of plastic 
suitable for injection molding. 
Referring now to FIG. 2, an enlarged partial sectional view shows the 
inducerpeller 30 of FIG. 1. The impeller 30 has mounted on its hub 30a, a 
rubber boot 31, a ceramic ring seal component 32, and a metal seal band 
33. The metal band dissipates sufficient heat to allow the seal and 
inducerpeller to run dry for a number of hours at high speeds. The front 
shroud 30b has stepped front surface wear ring surfaces 40,41. The vane 42 
has a leading edge portion (shown in shaded lines) 42a which flows 
smoothly into the axial impeller eye portion 30C and sweeps backward at 
angle of approximately 5.degree.-15.degree. to the axis of the 
inducerpeller. The leading edge portion facilitates smooth fluid flow 
transition represented by arrows 43 to 43a. 
FIGS. 3 and 3A further illustrate the motor fan according to the invention. 
The fan 55 includes thirteen full length blades 55a, thirteen short 
(splitter) vanes 55b, a hub 55c for pressing onto splined shaft, and a 
rear fan shroud 55d. The rear fan shroud 55d has a diameter 55e which is 
less than the diameter 55f. As described in the Summary of the Invention, 
the splitter vanes equally spaced between the full length blades improves 
the effective cooling, and the reduced shroud diameter improves the air 
flow at the discharge of the fan as it exits the motor housing. 
The fan features will be better understood by reference to FIG. 4 which is 
a partial cross-sectional view taken along lines 4--4 of FIG. 1 to show 
the effect of air flow through the fan and vents. Motor housing 20 has 
housing vents 20a, 20b for air exhaust from fan 55. Rear fan shroud 55d 
has a diameter 55e shorter than the outer diameter 55f to facilitate air 
flow represented by arrows 80,81 to the exhaust vents throughout the fan 
compartment 20c. In FIG. 4A, a peeler tongue 20d is shown in vent 20a 
close to the outer diameter of the fan blades/vanes, and as shown in FIG. 
4B, the motor housing 20 peeler tongue 20d is skewed at an angle 84 of 
approximately fifteen degrees with respect to the fan blades 55a to 
further reduce motor/fan noise. Without skewing, the high and low pressure 
sides of the blades/vanes cause higher pressure pulsations or increased 
noise. 
Referring now to FIG. 5, a series wound universal motor UV is normally 
controlled by a voltage control means 90 which is connected between the 
voltage source, for example, 115 volts, 60 cycles, and the motor leads. 
Although the specific type voltage control means is not the subject to 
this invention, it is well known that the voltage controls means function 
could be accomplished by an on-off switch 91, and a voltage variac 92 
which would vary the incoming voltage and thus the speed of the motor. In 
the preferred embodiment of the invention the series wound universal motor 
would have stator and armature winding to enable operation in the range of 
4000 to 9000 RPM which is desirable for the Whirlpool and Spa 
applications. 
While the present invention has been disclosed in connection with a 
preferred embodiment thereof, it should be understood that there may be 
other embodiments which fall within the spirit and scope of the invention 
as defined by the following claims.