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An Eaton M62 Roots-type supercharger is visible at the front of this Ecotec LSJ engine in a 2006 Saturn Ion Red Line.. The Roots-type blower is simple and widely used. It can be more effective than alternative superchargers at developing positive intake manifold pressure (i.e., above atmospheric pressure) at low engine speeds, making it a popular choice for passenger automobile applications.
A Roots blower is one extreme, a form of cycloid gear where the ratio of the pitch diameter to the generating circle diameter equals twice the number of lobes. In a two-lobed blower, the generating circle is one-fourth the diameter of the pitch circles, and the teeth form complete epi- and hypo-cycloidal arcs.
In 1875, Roots exhibited a blower at the Saint Petersburg Exhibition; Thwaites and Carbutt exhibited a Roots principle "air blowing machine" for mine ventilation in the same exhibition. [ 6 ] In 1885, Edgar Dwight Johnston joined the firm of 30 people; he became vice president in 1889 and president in 1898, remaining so until at least 1931.
The compressor is necessarily the core of the unit. Compressors used for this application are usually of the centrifugal type, or positive displacement units such as the Roots blowers, similar to the (much smaller) Roots type supercharger. Very large units (evaporation capacity 100 metric tons per hour or more) sometimes use Axial-flow compressors.
The term "blower" is applied to rotary screw, roots-type, and centrifugal compressors when utilized as part of an automotive forced induction system. The term 'cabin blower' is also used for the pressurisation of aircraft for high altitude flight, which used Roots type compressors particularly in the 1950s (see Marshall supercharger).
The EMD 645 is a family of two-stroke diesel engines that was designed and manufactured by the Electro-Motive Division of General Motors.While the 645 series was intended primarily for locomotive, marine and stationary engine use, one 16-cylinder version powered the 33-19 "Titan" prototype haul truck designed by GM's Terex division
The Roots supercharger dates back to the 1860s, and this is the basis for the original Wade supercharger, but with patented modifications incorporated. The first patent of Costin and Densham deals with ways to achieve compression within the Roots-style blower. [2]
The engine usually has a Roots blower to provide air for scavenging and this is arranged to deliver excess air so that air follows the exhaust gases into the exhaust manifold. Some of this air is then forced back into the cylinder by a rise in pressure in the exhaust manifold resulting from the exhaust pulse from another cylinder.