An improved automotive pump assembly includes a volute pumping chamber configured to operably contain a rotatable impeller which, when driven, draws fluid into a fluid inlet and pumps the fluid to and through a fluid outlet. The volute chamber has an exterior sidewall with a constant internal first radius over a first sidewall portion and transitions to a second sidewall portion of increasing radius. The chamber's second sidewall portion defines a first end at a sidewall transition point tangent to the constant radius sidewall segment to define a second end which is tangent to the volute chamber's fluid outlet with a second radius that is greater than the first radius.
1. A centrifugal pump assembly having a casing including a volute which defines a pumping chamber configured to operably contain a rotatable impeller having first, second and third transversely projecting impeller vanes, wherein said impeller, when driven, draws fluid into a fluid inlet and pumps the fluid to and through a fluid outlet, wherein said volute has an exterior sidewall that has a constant internal first radius over a first sidewall portion and transitions to a second sidewall portion of increasing radius; and wherein said second sidewall portion defines a first end at a sidewall transition point which is tangent to said constant radius sidewall segment, and defines a second end which is tangent to said volute's fluid outlet and has a second radius that is greater than said first radius.
2. The pump assembly of claim 1 , wherein said pump volute's sidewall defines a spiral deviation wherein the pump chamber's radial sidewall flares away from the swept area of the impeller's vanes and defines a fluid outlet that contributes to higher P-Q performance, especially when pumping colder fluids.
3. The pump assembly of claim 2 , wherein said volute sidewall has a constant internal diameter or circular profile for approx. 260 degrees, providing constant clearance with impeller and then, approaching the outlet, transitions to a gradually increasing clearance all the way to the outlet, where the casing radius is 1.6 times the radius of the casing sidewall's circular profile.
4. The pump assembly of claim 2 , wherein said impeller has a central axis of rotation and a central shaft aligned along said impeller's axis of rotation and carrying said first, second and third transversely projecting impeller vanes wherein each of said first, second and third transversely projecting impeller vanes comprises a radially projecting curved primary vane; wherein each primary vane has a twist in the radial direction so that each vane has provides an angled, convex leading surface; wherein said impeller also has a plurality of radially projecting secondary vanes affixed to said central shaft such that each secondary vane is also aligned with and affixed to one of said radially projecting curved primary vanes.
5. The pump assembly of claim 4 , wherein said impeller's secondary impeller vanes are each configured to define a triangular connecting fillet-like wall segment connected to a primary vane and to the impeller shaft.
6. The pump assembly of claim 5 , wherein said impeller's secondary impeller vanes are each twisted so that the leading surface of the secondary vane is angled or twisted to match the primary vane's leading surface and define a contiguous surface across both the primary vane and it's secondary vane.
7. The pump assembly of claim 6 , wherein said volute's inlet is axially aligned with said impeller's central axis of rotation in a bottom inlet configuration.
8. The pump assembly of claim 6 , wherein said volute's inlet is axially aligned with said impeller's central axis of rotation in a side inlet, top feed configuration.
9. A centrifugal pump assembly having a casing including a volute which defines a pumping chamber configured to operably contain a rotatable impeller which, when driven, draws fluid into a fluid inlet and pumps the fluid to and through a fluid outlet, wherein said volute has an exterior sidewall that has a constant internal first radius over a first sidewall portion and transitions to a second sidewall portion of increasing radius; and wherein said second sidewall portion defines a first end at a sidewall transition point which is tangent to said constant radius sidewall segment, and defines a second end which is tangent to said volute's fluid outlet and has a second radius that is greater than said first radius;
said pump volute's sidewall defining a spiral deviation wherein the pump chamber's radial sidewall flares away from the swept area of the impeller's vanes and defines a fluid outlet that contributes to higher P-Q performance, especially when pumping colder fluids; and
wherein said impeller has a central axis of rotation and a central shaft aligned along said impeller's axis of rotation and carrying a plurality of radially projecting curved primary vanes; wherein each primary vane has a twist in the radial direction so that each vane has provides an angled, convex leading surface; wherein said impeller also has a plurality of radially projecting secondary vanes affixed to said central shaft such that each secondary vane is also aligned with and affixed to said radially projecting curved primary vanes.
10. The pump assembly of claim 9 , wherein said impeller's secondary impeller vanes are each configured to define a triangular connecting fillet-like wall segment connected to a primary vane and to the impeller shaft.
11. The pump assembly of claim 10 , wherein said impeller's secondary impeller vanes are each twisted so that the leading surface of the secondary vane is angled or twisted to match the primary vane's leading surface and define a contiguous surface across both the primary vane and it's secondary vane.
12. The pump assembly of claim 11 , wherein said volute's inlet is axially aligned with said impeller's central axis of rotation in a bottom inlet configuration.
13. The pump assembly of claim 11 , wherein said volute's inlet is axially aligned with said impeller's central axis of rotation in a side inlet, top feed configuration.