Intake port for an internal-combustion engine

An intake port for an internal-combustion engine is composed of an inlet duct which is constructed in the cylinder head and has a more curved section close to the combustion space and a flat or less curved section away from the combustion space. The inlet duct is adjoined by an intake connection piece which is fastened to the cylinder head and is connected wit the intake system. In the intake port formed of the intake connection piece and the inlet duct, a guiding device is constructed which is arranged in the inlet duct and extends into the more curved area of the inlet duct. The guiding device includes a movable section to differently guide the inlet duct flow as a function of engine operating conditions.

BACKGROUND AND SUMMARY OF THE INVENTION
 This application claims the priority of German application 197 54 736.2,
 filed in Germany on Dec. 10, 1997.
 The invention relates to an intake port for an internal-combustion engine.
 Especially preferred embodiments relate to an intake port for an
 internal-combustion engine which has a combustion space which is at least
 partially constructed in a cylinder head and which, by way of at least one
 valve-controlled inlet duct leading into its roof section, is acted upon
 with air or with a fuel air mixture, the inlet duct constructed in the
 cylinder head having a more curved section facing the combustion space and
 a less curved section away from the combustion space, and changing into an
 intake connection piece adjoining the cylinder head, which intake
 connection piece, together with the inlet duct forming the intake port and
 being connected with the intake system, and having a guiding device
 arranged in the intake port and having an adjustable guiding section.
 An intake port of this type is described, for example, in German Patent
 Document DE 44 37 279 A1 and is composed of an inlet duct constructed in
 the cylinder head and of an intake connection piece flanged to the
 cylinder head, which intake connection piece is connected with the intake
 system of the internal-combustion engine. In the intake connection piece,
 a receiving device for an injection nozzle is constructed whose fuel jet
 is directed into the inlet duct. Furthermore, a guiding device with a
 swivellable guiding section is arranged in the intake connection piece,
 which guiding section is constructed on the side of the guiding device
 facing away from the cylinder head. This guiding device is arranged such
 in the intake connection piece that it projects into the entrance area of
 the inlet duct. In addition to the defined port geometry, this guiding
 device has the purpose of causing, in the case of a low engine
 load--idling and partial load--a targeted tumble in the combustion space.
 However, such guiding devices have the disadvantage that they have a
 throttling effect at higher rates of air flow in the nominal output range
 and thus counteract an optimal port construction for the nominal output
 range. Furthermore, in the case of such intake port geometries,
 detachments of the flow on the port section inside the curvature will
 occur in the area of the more curved inlet duct section so that this also
 has a disadvantageous influence on the mixture preparation in the nominal
 output range.
 With respect to the above, it is an object of the invention to improve an
 intake port of the above-mentioned type for an internal-combustion engine
 such that, at low air rates of air flow in the idling and partial load
 range, the mixture preparation is improved by the targeted tumble
 generating in the combustion space and simultaneously a higher and more
 uniform rate of air flow in the nominal output range of the
 internal-combustion engine is ensured.
 According to the invention, this object is achieved by providing that the
 guiding device is arranged in the inlet duct and, by means of its area
 close to the combustion space, reaches at least approximately into the
 more curved section of the inlet duct.
 By the arrangement of the guiding device in the inlet duct and the
 dimensioning of the guiding device into the more curved section of the
 inlet duct close to the combustion space, as a function of the position of
 the adjustable guiding section, a targeted tumbling formation can be
 caused as well as a stabilizing of the flow at higher rates of air flow.
 Particularly at high rates of air flow in the normal output range, this
 arrangement of the guiding device contributes to a stabilizing of the flow
 by way of the port cross-section and can furthermore counteract
 separations of the flow at the port section on the inside of the
 curvature. By means of such an arrangement of the guiding device, an
 improvement of the mixture preparation can therefore be achieved along
 almost the whole usage range of the internal-combustion engine, during
 idling and in the partial load range, a combustion-promoting tumbling
 formation being promoted and, at higher rates of air flow in the nominal
 load range, a targeted flow and a high rate of air flow being achieved.
 The generating of a tumbling in the combustion space for improving the
 mixture preparation during idling and in the partial load range becomes
 particularly effective if the adjustable guiding section of the guiding
 device is constructed on the part of the guiding device close to the
 combustion space. As a result, particularly in the more curved section of
 the inlet duct, an effective diversion or deflection of the air flow can
 be achieved, without any weakening of the flow effect caused by the
 guiding device by disturbing influences from the port geometry.
 By the construction of the guiding device as a baffle and the adaptation of
 this baffle to the course of the curvature of the inlet duct in the flow
 direction, particularly for high rates of air flow, a particularly
 effective stabilizing of the flow can be achieved along the whole port
 cross-section and particularly at the port section on the inside of the
 curvature.
 A particularly advantageous construction of the guiding device is achieved
 for multi-cylinder internal-combustion engines if the adjustable guiding
 section is operated by means of a swivelling axis or swivelling shaft
 penetrating the inlet duct, and this swivelling axis or swivelling shaft
 is arranged in parallel to the longitudinal course of the
 internal-combustion engine. By means of this arrangement, the swivelling
 axis or swivelling shaft can be constructed such that, in one piece, it
 penetrates the respective inlet ducts situated behind one another, and the
 adjustable guiding sections of all cylinders arranged behind one another
 are therefore adjustable by means of an operating element.
 A particularly good tumble formation is achieved if the guiding device
 divides the inlet duct into an upper and a lower guiding section or into a
 guiding section on the outside and on the inside of the curvature and, for
 the tumble formation in the combustion space, the lower guiding section or
 the guiding section on the inside of the curvature is largely closed.
 Other objects, advantages and novel features of the present invention will
 become apparent from the following detailed description of the invention
 when considered in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE DRAWINGS
 In FIG. 1, the cylinder head of a multi-cylinder internal-combustion engine
 has the reference number 1, the charge cycle of this internal-combustion
 engine 1 being controlled by four charge cycle valves per cylinder. In the
 cylinder head 1, the roof section 2 of the combustion space 3 is
 constructed for each cylinder. Two circular inlet openings respectively
 and two also circular outlet openings are constructed in this roof
 section, of which only one inlet 4 and one outlet 5 are shown here. Each
 inlet opening is simultaneously the mouth section of an inlet duct 6 which
 is constructed in the cylinder head and which is penetrated by an inlet
 valve 7 interacting with the inlet opening. This inlet duct 6 has a
 section 8 which is away from the combustion space and the course of whose
 axis has a straight or only slightly curved construction. This section 8
 away from the combustion space changes into a more curved section 9 close
 to the combustion space, which more curved section leads into the
 combustion space 3. The section 8 away from the combustion space reaches
 to a side surface 10 of the cylinder head and changes there to an intake
 connection piece 11 which is flanged to the cylinder head 1 and which is
 connected with the only partially illustrated intake system 12. Further, a
 receiving device 13 for an injection valve 14 is constructed on the intake
 connection piece 11 and is arranged in the upper area of the intake
 connection piece facing away from the combustion space. The injection
 valve 13 is arranged such in a manner known per se that the generated fuel
 jet enters into the inlet duct 6 in the upper area of the inlet duct 6 and
 the jet axis is aligned with the center of the inlet opening 15. However,
 it is also easily possible to construct the internal-combustion engine as
 a direct-injecting internal-combustion engine, in which case then the
 injection valve is arranged such on the cylinder head that the fuel jet is
 entered directly into the combustion space 3.
 Along a major and important portion of its length, the inlet duct 6 is
 divided into an upper port section 17 and into a lower port section 18 by
 means of a guiding device constructed as a baffle 16. This baffle 16 is
 curved in the direction of the flow course, the line of curvature
 following largely the course of the inlet duct axis 19. Perpendicularly to
 the flow direction or perpendicularly to the intersection plane
 illustrated in FIG. 1, the baffle 16 is constructed to be approximately
 planar. The baffle 16 is arranged such that it extends below the port axis
 19, and the upper port section 17 and the lower port section 18 have a
 cross-sectional surface ratio of approximately two to one.
 The baffle is fastened on a swivelling shaft 20 penetrating the inlet duct
 6, the rotation of this swivelling shaft 20 being able to change the
 position of the baffle. The swivelling position of the baffle illustrated
 in FIG. 1 is designed for the operation of the internal-combustion engine
 at high rates of air flow in the nominal output range. The alignment of
 the baffle is such that the air flow encounters only very little
 resistance, and the air flow takes place via the upper port section 17 and
 the lower port section 18. By means of this division of the inlet duct, a
 separation of the flow is prevented particularly in the area of the lower
 port section in the area of the most pronounced port curvature.
 In the case of the switching or swivelling position of the baffle 16
 illustrated in FIG. 2, the lower port section 18 is largely closed in that
 the end of the baffle facing away from the combustion space rests against
 the port wall. Simultaneously, the flow cross-section of the upper port
 section tapers along the length of the port. This change of the port
 cross-section promotes a targeted tumbling formation in the combustion
 space during idling and in the partial load operation of the
 internal-combustion engine.
 In the modification of the embodiment illustrated in FIG. 3, the baffle 21
 is fixedly arranged in the inlet duct 6. By means of this fixed baffle 21,
 the inlet duct 6 is also divided into an upper port section 17 and a lower
 port section 18; the surface ratios of the upper port and lower port duct
 sections 17, 18 correspond to those of the first embodiment. In this
 modification, the baffle 21 ends in the area of the transition from the
 less curved section 8 to the more curved section 9 of the inlet duct 6. At
 the end of the fixed baffle 21, a swivellable guiding section 22 is
 disposed which extends into the proximity of the inlet valve 7. In the
 alignment of the swivellable guiding section 22 indicated by a solid line,
 the fixed baffle 21 is lengthened by section 22 in an aligned manner. This
 switching or swivelling position of the swivellable guiding section is
 provided for the operation of the internal-combustion engine with a high
 rate of air flow-as described above. For the operation of the
 internal-combustion engine during idling and in the partial load range,
 the swivellable guiding section 22 is swivelled into the position
 illustrated by a broken line so that this guiding section 22 will rest
 against the lower port wall of the inlet duct 6 and close the lower port
 section 18 and simultaneously will reduce the passage cross-section of the
 upper port section 17. This swivelling position again promotes the
 tumbling formation in the combustion space.
 In the case of the construction and arrangement of the guiding device, it
 is easily possible to let this guiding device project in the area close to
 the combustion space into the area of the inlet valve. For example, the
 valve stem of the inlet valve can then be surrounded by a corresponding
 recess in the baffle 16 or in the swivellable guiding section 22. This
 recess, which is schematically depicted in FIGS. 1A and 1B, must them be
 constructed such that the valve stem of the inlet valve is surrounded
 without any contact in all swivelling positions of the baffle 16 or of the
 swivellable guiding section;
 FIG. 1A schematically depicts section A from FIG. 1, with a modified
 embodiment having a recess 16R which can reach around the valve stem 7.
 FIG. 1B shows the arrangement of FIG. 1A in a sectional plan view from
 above.
 FIG. 4 schematically depicts an arrangement with multiple cylinders with a
 single swiveling shaft 20 extending through inlet ducts 4 of respective
 adjacent aligned cylinders arranged behind one another, to thereby provide
 for a common operating element for adjusting the adjustable guiding
 sections of all of the cylinders.
 In contrast to the illustrated use, an intake port having such a guiding
 device is particularly suitable for internal-combustion engines with a
 direct gasoline injection, in which a mixture preparation on the hot inlet
 duct walls is not required in contrast to the intake pipe injection.
 The foregoing disclosure has been set forth merely to illustrate the
 invention and is not intended to be limiting. Since modifications of the
 disclosed embodiments incorporating the spirit and substance of the
 invention may occur to persons skilled in the art, the invention should be
 construed to include everything within the scope of the appended claims
 and equivalents thereof.