How the electro-mechanical valve train accelerates logistics and reduces costs

Abstract

Engines using a mechanical variable valve train (MVVT) have improved torque, emissions and efficiency as valve timing on both the intake and outlet camshafts can be adjusted to the power required from the engine as a function of gas pedal position and engine speed. This valve train system has been in mass production since 2002 and is produced by BMW under the name VANOS. The electro-mechanical valve train (EMVT) goes beyond mechanically manipulating valve positions and enables the independent control of single valves by separate electronic operation. From a performance point of view, this enables a further reduction in fuel consumption and exhaust emissions, whilst increasing engine output. From a production and logistics perspective a number of advantages result from the EMVT. While the MVVT consists of 33 components with a total of 160 single parts, the EMVT is built from only four components with 85 single parts. This simplification of the product directly affects assembly and logistics. The EMVT will result in a significant shortening of the assembly process as approximately one-third of the assembly steps for the MVVT will be omitted without replacement. Consequently, assembly costs, material supply and handling costs, as well as assembly lead time are greatly reduced. The EMVT has fewer, higher density parts. Whilst this causes an increase in weight, it decreases the storage volumes required by an estimated 80%. The EMVT further benefits the inbound supply chain, as 18 suppliers have to be coordinated for production of the MVVT, but as few as three suppliers can deliver the EMVT components. The consequence is a drastic reduction in inbound logistics complexity, and an assessment has shown a transport cost reduction of up to 40%. It has become apparent that the EMVT is a key example of how product design can improve production and logistics processes. It can also provide significant cost advantages and a considerable reduction in production lead time. © 2008 Springer-Verlag.