Joined Nov 2004
158 Posts | 0+
I have been musing on the technicalities of engines with a few people recently as I often do. We were trying to figure out why trochoidal rotor or gear type oil pumps are used in modern racing engines with roller bearing big-ends/??
Bearing in mind the following:
Oil pressures are comparatively low, max 30-40 psi
(Dale was kind enough to confirm the Husaberg oil pressure http://www.husaberg.org/modules.php?nam ... l+pressure)
Trochoidal (the name for curves generated by rolling a point on one circle around another circle) and gear pumps are very inefficient at low pressures. In some tests I did on this once I got a figure of about 15% efficiency for a gear pump at 45 psi, but over 75% at 1000 psi.
Centrifugal (i.e. like water pumps) pumps are much more efficient at low pressures and can easily generate a head of 30-40 psi. On top of that they are much easier to manufacture and reliable by virtue of their simplicity.
What we concluded was:
A centrifugal pump could supply oil in a modern engine if it served only to move oil from one place to the other and was not intended to pressure feed bearings.
Gear and Trochoidal pumps may simply be included because they are “traditionalâ€Â
Bearing in mind the following:
Oil pressures are comparatively low, max 30-40 psi
(Dale was kind enough to confirm the Husaberg oil pressure http://www.husaberg.org/modules.php?nam ... l+pressure)
Trochoidal (the name for curves generated by rolling a point on one circle around another circle) and gear pumps are very inefficient at low pressures. In some tests I did on this once I got a figure of about 15% efficiency for a gear pump at 45 psi, but over 75% at 1000 psi.
Centrifugal (i.e. like water pumps) pumps are much more efficient at low pressures and can easily generate a head of 30-40 psi. On top of that they are much easier to manufacture and reliable by virtue of their simplicity.
What we concluded was:
A centrifugal pump could supply oil in a modern engine if it served only to move oil from one place to the other and was not intended to pressure feed bearings.
Gear and Trochoidal pumps may simply be included because they are “traditionalâ€Â
