Concentric Pumps Ltd. has so far won five development contracts from major European and North American OEMs for its innovative variable flow oil pump (VFP) which is designed to use significantly less power and fuel than conventional fixed flow pumps, as well as offering the potential for a more energy-efficient oil system.

The contracts have come from both engine and vehicle manufacturers, for on and off-road applications and petrol as well as diesel engines. The VFP oil pump was originally developed for heavy-duty diesel engines, where it has demonstrated savings of between 3 and 4hp at rated speed and more than 1hp at cruise speed. Kevin Johanson, Concentric's Business Manager, Variable Flow, commented: "Initially, we assumed the advantages in terms of reducing parasitic loss would be of most interest in the context of commercial diesels operating off-road or trucks with stop-start duty cycles. However, in talking to engineers in the major automotive companies, we discovered there was just as much interest in the technology for petrol engines and high-performance passenger cars, where the new European drive cycle (NEDC), with a cold start and significant running time below 80ºC means that the lube system is responsible for an even higher proportion of parasitic losses. In addition, our latest design of is more compact than the previous version, so any packaging disadvantages compared with a conventional pump are relatively insignificant. This is an important advance for the passenger car market." All Concentric's VFP contracts are in new engine programmes and advanced technology projects, where the benefits can be maximized by matching oil supply to demand, so as to take advantage of the differing oil requirements for each point in the operating cycle. This is equally relevant to medium and light duty engines, which often operate at high speed and part load. In a typical duty cycle, such engines often do not reach a stable 80ºC for long periods and the regulating valve can operate prematurely, providing the opportunity for further energy saving. Concentric's VFP pump is an annulus and rotor design, which offers superior durability, compactness and economy. Its principle is to align flow to demand, so limiting the power needed to drive the pump and hence fuel consumption. Two rotor sets control flow output. The driving rotor operates in the traditional, fixed arrangement while the offset position and resultant flow of the second, eccentrically-mounted rotor can be controlled mechanically by a rack and pinion or electronically. Based in Birmingham, UK, Concentric Pumps Ltd is one of three manufacturing plants within the Concentric Group, a major supplier to the world's truck, agricultural and construction equipment industries. The company manufactures oil, water and fuel transfer pumps, as well as integrated front cover assemblies for diesel engines. In addition, it also supplies lubrication pumps for transmissions and reciprocating compressors.

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