Friday, January 26, 2001
Escanaba, MI--An entirely new class of water pump from
Engineered Machined Products Inc. improves flow control, reduces warrantee
costs, and boosts efficiency compared to conventional pulley-driven
engine-cooling pumps. The secret: an integral liquid-cooled electric drive motor
and a proprietary mixed-flow impeller and diffuser design.
Using either a switched reluctance or brushless permanent magnet
motor, the E.M.P. Advanced Electric Pump generates coolant flow rate based on
engine temperature rather than engine speed. "We don't have the only electric
water pump in the world," explains E.M.P. VP of Product Development David Allen.
"But our integral motor design allows higher efficiencies because we can liquid
cool it instead of using a fan."
Moreover, elimination of side loads induced by belts or gears
effectively doubles bearing life and creates a favorable environment for seals
because they are no longer subject to shaft deflections associated with drive
mechanism loading. In fact, the motor-driven pump uses smaller, less-expensive
bearings than traditional pumps and requires no external mechanical seals.
Since the location of the drive mechanism determines placement of
a conventional pump on the engine, it typically requires more time and labor to
replace, according to E.M.P. President Brian Larche. "It also means large parts
inventories with literally hundreds of conventional water pump designs." In
contrast, the E.M.P. pump's in-line design eliminates the need for custom-built
pumps, and will decrease pump inventory for both military and commercial
applications because it can mount anywhere in the engine compartment.
But fluid-pumping efficiency is the real key to success in any
application. Most water pumps use a volute, or spiral-scroll-shaped form
machined at the edge of the impeller to decrease turbulence in fluid exiting the
pump, Allen explains. "However, fluid coming off the impeller bombards fluid in
the volute and actually decreases efficiency."
Instead, the new E.M.P. pump uses a diffuser that immediately
redirects fluid as it comes off the impeller into a stationary set of vanes,
isolating it from impeller interference. "This boosts efficiency because the
diffuser collects fluid from the impeller for a full 360 degrees as compared to
approximately 90 degrees of a volute style pump," says Allen.
At half the size of conventional over-the-road engine cooling
pumps, the patented, fully controllable E.M.P. Pump increases efficiency 30% and
reduces weight 60%. The pump and controls thermally optimize the engine for a 3
to 7% increase in fuel economy. It also reduces emissions and cools the engine
components after shutdown to decrease thermal fatigue. For more information