Turbo-charged internal combustion engine

A five-cylinder turbocharged internal combustion engine has an exhaust manifold (6-10) connected to a turbine housing (13). Four exhaust manifold conduits (7, 8, 9, 10) lead in pairs to the inlets (11, 12) of a twin-entry turbine (14). The fifth exhaust manifold conduit (6) is drawn past the turbine housing and opens into an exhaust pipe (18) on the downstream side of the turbine housing.

The present invention relates to a five-cylinder turbo-charged internal
 combustion engine with an exhaust manifold connected to a turbine housing,
 said manifold comprising five exhaust manifold conduits, of which four are
 combined in pairs and open into an inlet into the turbine housing.
 U.S. Pat. No. 4,207,742 reveals as previously known a five-cylinder engine
 of this type which has a turbine housing with three inlet openings opening
 into a common inlet channel to the interior of the turbine housing. The
 pairs of exhaust manifold conduits are each connected to a larger inlet
 opening, while the fifth exhaust manifold conduit is connected to its own
 smaller inlet opening. A five-cylinder engine places higher demands on the
 design of the exhaust manifold than a four-cylinder engine does due to the
 fact that the overlap between the exhaust valves in the open position is
 greater than in the four-cylinder engine, and therefore the risk of the
 cylinders disrupting each other during gas exchange is greater. The
 described distribution makes possible a form of three-pulse supercharging
 which limits the disturbing influence of the cylinders on each other
 during gas exchange.
 In the above described known engine, the exhaust manifold conduit of the
 one outer cylinder is directly connected to the turbine housing. The
 exhaust manifold conduit from the next cylinder flows together with the
 exhaust manifold conduit of the second outer cylinder, and the two exhaust
 manifold conduits of the two remaining cylinders are combined with each
 other. This means that if we disregard the cylinder with the separate
 exhaust manifold conduit, the exhaust manifold conduits from the other
 four cylinders are grouped in the same manner as is common in a
 four-cylinder engine, i.e. the exhaust manifold conduits from the outer
 cylinders flow together, as do the exhaust manifold conduits from the
 middle cylinders.
 One purpose of the purpose invention is in general, starting from the above
 design, to achieve increased component compatibility between the
 four-cylinder and the five-cylinder engines. An additional purpose of the
 invention is to achieve a five. cylinder engine of the type described by
 way of introduction, which has a basic design which makes possible both
 true pressure-wave super-charging and lower emissions at start.
 This is achieved according to the invention by virtue of the fact that the
 fifth exhaust manifold conduit is drawn past the turbine housing and opens
 into an exhaust pipe on the downstream side of the turbine housing.
 The invention is based on the insight that the disadvantage of not
 utilizing the energy from the fifth cylinder to drive the turbine is less
 than the other advantages which can be achieved, for example, the
 elimination of pressure-waves from the fifth cylinder which can disturb
 other cylinders. A result will be that an exhaust manifold conduit with
 associated turbine for a four-cylinder engine can be used without
 modification on a five-cylinder engine. This, of course, presupposes that
 the only difference between the four and five-cylinder engine is the
 number of cylinders.
 In order to fully exploit the advantages of allowing only four cylinders to
 drive the turbine of a five-cylinder engine, there is utilized in a
 further development of the basic invention an exhaust turbine of so-called
 twin-entry type, which has a turbine housing with a separate inlet for
 each of two separate inlet channels to the interior of the turbine
 housing. By connecting a pair of exhaust manifold conduits to each turbine
 inlet, true pressure-wave super-charging is achieved in a five-cylinder
 engine as well, which improves the values for residual gas and degree of
 filling, especially at low rpm where the response is determined.
 It is previously known in the exhaust manifold of a suction engine to
 arrange an extra so-called start-up catalytic converter which, by virtue
 of its placement close to the engine cylinders, will be more rapidly
 warmed up than the ordinary main catalytic converter placed in the exhaust
 pipe. The extra catalytic converter contributes to more rapid warming-up
 of the main catalytic converter, and this results in lower emissions at
 start.
 In a preferred embodiment of an engine according to the invention, which,
 in an exhaust conduit on the downstream side of the turbine housing, has a
 catalytic exhaust cleaner, the fifth exhaust manifold conduit opens into
 said exhaust pipe upstream of the exhaust cleaner and contains an
 additional catalytic exhaust cleaner. A catalytic exhaust cleaner creates
 a certain exhaust counter-pressure and can therefor not be placed in the
 exhaust manifold between the engine block and the turbine housing in a
 turbo engine, but the arrangement with a fifth exhaust manifold conduit
 drawn past the turbine makes it possible to also utilize a start-up
 catalytic converter in a turbo engine. The catalytic converter also
 contributes here to creating an exhaust counter-pressure in balance with
 the counter-pressure which the turbine generates in the other four exhaust
 manifold conduits.

The engine shown in the FIGURE has an engine block with five cylinder 1, 2,
 3, 4 and 5, the exhaust blow-out opening into five exhaust manifold
 conduits 6, 7, 8, 9 and 10, of which the exhaust manifold conduits 7 and 8
 combine into a pair, as do the exhaust manifold conduits 9 and 10. The
 respective exhaust manifold conduit pairs 7, 8 and 9, 10 each open into an
 individual inlet 11, 12 in the turbine housing 13 of a turbo compressor
 which has a turbine portion 14 of so-called twin-entry type. The turbine
 portion 14 drives a compressor portion 15, which feeds inlet air to the
 inlet manifold 16 of the engine. The turbine housing 13 has an outlet 17,
 which is connected to an exhaust pipe 18 opening into a catalytic exhaust
 cleaner 19.
 According to the invention, the exhaust blow-out from the first cylinder 1
 opens into an exhaust manifold conduit 6, which is drawn past the turbine
 housing 13 and opens into the exhaust pipe 18 between the turbine housing
 13 and the catalytic converter 19. The exhaust manifold conduit 6 contains
 a start-up catalytic converter 20 which, due to its proximity to the
 cylinder 1, is rapidly heated and contributes to rapid warming-up of the
 main catalytic converter 19.
 Even if the invention above has been described with reference to one
 example in which the first cylinder is shunted past the turbine, it is of
 course easily recognized within the scope of the invention that any
 cylinder at all can be selected to be shunted past the turbine, depending
 on suitability for the engine installation in question.