JP2016169713A - Intake port structure of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To strengthen a swirl flow within a fuel chamber without making the structure of an engine complex.SOLUTION: An intake port structure of an engine includes a plurality of intake ports 5. A center o2 of an intake valve 6 in the intake port 5 is eccentric toward an exhaust port 7 from a center o1 of an inner face 24 of a seat ring 20, and is eccentric toward either side of intake/exhaust parallel lines E1, E2 parallel to an intake/exhaust center line A passing through a center o2 of the inner face 24 of the seat ring 20 and connecting between an intake side center D and exhaust side center C of an inner peripheral wall 3a of a cylindrical bore. A throat portion 22 of a seat ring 20 constitutes an eccentric suction port in which an eccentric side of the center o2 of the intake valve 6 is formed relatively deeper than other sides along an eccentric direction lines F1, F2 connecting between the center o2 of the intake valve 6 and the center o1 of the inner face 24 of the seat ring 20. A cross sectional area of a flow channel formed by inner faces of the intake ports 5 successive in an upstream side of the inner face 24 of the seat ring 20 is set smaller than that of the inner face 24 of the seat ring 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an intake port structure of an engine that enhances a swirl flow of intake air in a combustion chamber.

  Various engines that generate a so-called swirl flow in an arc direction along the inner peripheral wall of the combustion chamber have been proposed. It is said that the occurrence of swirl flow in the combustion chamber induces turbulence of intake air in the combustion chamber, thereby improving the combustion speed and suppressing knocking under predetermined conditions.

  In order to generate a swirl flow, the valve is operated in a normal opening / closing mode in which all of the plurality of intake valves and exhaust valves are opened and closed, and a part of the plurality of intake valves and exhaust valves is opened and closed, and the intake air in the combustion chamber is Can be switched to a partial open / close mode for generating a swirl flow. In some cases, an intake flow control valve is provided in an intake passage leading to the combustion chamber in order to generate a swirl flow.

  Further, in Patent Documents 1 and 2, in order to enhance the swirl flow of the intake air in the combustion chamber, the shape of the seat ring provided at the opening to the combustion chamber of the intake port is centered on the inner diameter with respect to the outer diameter center A technique is adopted in which it is decentered or tapered so as to gradually expand toward the combustion chamber along the flow direction of the swirl flow.

Japanese Patent Laid-Open No. 10-195896 Japanese Utility Model Publication No. 5-75453

  As described above, enhancing the swirl flow in the intake air in the fuel chamber is effective in improving the combustion speed and reducing knocking.

  However, the inflow direction of the intake air from the intake port to the combustion chamber is basically a direction parallel to the direction connecting the intake side and the exhaust side across the cylinder axis of the combustion chamber. This inflow direction is usually also a direction orthogonal to the axial direction of the crankshaft in a plan view of the cylinder of the engine. For this reason, the direction of the swirl flow to be generated in the combustion chamber, that is, the arc direction along the inner peripheral wall of the combustion chamber, and the inflow direction of intake air into the combustion chamber are different from each other. In order to strengthen the swirl flow, it is desirable that the arc direction of the swirl flow and the inflow direction of the intake air are close to each other.

  Here, in order to reinforce the swirl flow, it is also possible to adopt a method of adding various valve devices and nozzles in the intake passage. However, adding such a device has a limit because it leads to a complicated engine structure and an increased cost.

  On the other hand, as in Patent Documents 1 and 2, devising the shape of the seat ring is effective for strengthening the swirl flow. However, there is still room for improvement in order to further increase the combustion rate and the effect of reducing knocking.

  Therefore, an object of the present invention is to enhance the swirl flow in the fuel chamber without complicating the structure of the engine.

  In order to solve the above problems, the present invention provides an intake port connected to an intake side of an engine combustion chamber, an exhaust port connected to an exhaust side of an engine combustion chamber, the intake port and the exhaust port An annular seat ring provided in a region facing the combustion chamber, and an intake valve and an exhaust valve that are in contact with and away from the seat ring, and the center of the intake valve in the intake port is more than the center of the inner surface of the seat ring Intake / exhaust that is eccentric to the exhaust port side and is parallel to the intake / exhaust center line that connects the intake side center and the exhaust side center of the inner peripheral wall of the cylinder bore that forms the combustion chamber through the center of the inner surface of the seat ring Eccentric on either side across a parallel line, the throat portion of the seat ring is an eccentric way connecting the center of the intake valve and the center of the inner surface of the seat ring An eccentric intake port in which the eccentric side of the center of the intake valve along the line is formed relatively deeper than the other, in plan view along the axial direction of the seat ring in the eccentric intake port, The intake air of the engine in which the cross-sectional area of the flow path formed by the inner surface of the intake port continuous upstream of the inner surface of the seat ring is set smaller than the cross-sectional area of the flow path formed by the inner surface of the seat ring Adopted port structure.

  Here, a plurality of the intake ports are provided, and the plurality of intake ports are the eccentric intake ports, and the centers of the intake valves in the eccentric intake ports are the same across the corresponding intake / exhaust parallel lines. It is possible to employ a configuration that is eccentric to the side of the.

  Further, among the plurality of eccentric intake ports, the angle formed by the eccentric direction line and the intake / exhaust parallel line in the eccentric intake port on one side where the center of the intake valve is far from the axis of the cylinder bore is the other side. A configuration can be adopted in which the eccentric intake port is set to be smaller than the angle formed by the eccentric direction line and the intake / exhaust parallel line.

  In each of these configurations, the inner surface of the intake port that is continuous with the upstream side of the inner surface of the seat ring in the eccentric intake port has a cylinder bore along the eccentric direction line in a plan view along the axial direction of the seat ring. An inner surface matching portion flush with the inner surface of the seat ring on the rear end side far from the axial center of the seat ring, and a protruding portion protruding inward from the inner surface of the seat ring at any other portion, the protruding portion It is possible to adopt a configuration in which the cross-sectional area of the flow path at a certain position is smaller than the cross-sectional area of the flow path of the seat ring.

  In the configuration including a plurality of the eccentric intake ports, the upstream side of the inner surface of the seat ring in the eccentric intake port on one side of the plurality of the eccentric intake ports, the center of the intake valve being far from the axis of the cylinder bore The inner surface of the intake port continuous to the inner surface of the seat ring is flush with the inner surface of the seat ring on the rear end side far from the axis of the cylinder bore along the eccentric direction line in a plan view along the axial direction of the seat ring. Provided with a projecting portion projecting inward from the inner surface of the seat ring on the front end side near the axial center of the cylinder bore along the eccentric direction line, and having a cross-sectional area of the flow path at the location where the projecting portion is located. The intake port that is smaller than the cross-sectional area of the flow path of the seat ring and that is continuous with the upstream side of the inner surface of the seat ring in the eccentric intake port on the other side The inner surface of the seat ring includes an inner surface coincident portion that is flush with the inner surface of the seat ring on a front end side close to the axis of the cylinder bore along the eccentric direction line in a plan view along the axial direction of the seat ring. A projecting portion projecting inward from the inner surface of the seat ring on the rear end side far from the axis of the cylinder bore along the direction line; It is possible to adopt a configuration that is smaller than the cross-sectional area.

  In each of these configurations, the inner surface of the intake port that is continuous to the upstream side of the inner surface of the seat ring in the eccentric intake port is aligned with the front end side near the axis of the cylinder bore and the eccentric direction line along the eccentric direction line. A configuration in which the maximum diameter in the front-rear direction connecting the rear end side far from the axis of the cylinder bore along the longitudinal direction is set larger than the maximum diameter in the width direction orthogonal thereto.

  In the present invention, the center of the intake valve in the intake port is decentered toward the exhaust port side from the center of the inner surface of the seat ring, and passes through the center of the inner surface of the seat ring to the intake side center and the exhaust side center of the inner peripheral wall of the cylinder bore. Eccentric to either side across the intake / exhaust parallel line that is parallel to the intake / exhaust centerline, and the depth of the throat of the seat ring is relatively deeper at the eccentric side of the center of the intake valve Configured eccentric intake port. Further, in the eccentric intake port, the cross-sectional area of the flow path formed by the inner surface of the intake port continuous upstream of the inner surface of the seat ring is smaller than the cross-sectional area of the flow path formed by the inner surface of the seat ring. Was set as follows. With this configuration, the flow of the intake air introduced into the combustion chamber in the eccentric intake port in the swirl direction can be promoted, and the swirl flow in the fuel chamber can be enhanced. That is, the swirl flow in the fuel chamber can be enhanced without complicating the engine structure.

FIG. 2 is an enlarged plan view of a main part of a combustion chamber and an intake port according to an embodiment of the present invention. It is a principal part top view of the combustion chamber and intake port of the embodiment. It is a principal part enlarged view of the intake port which shows the embodiment. (A) (b) is explanatory drawing which shows the processing method of an intake port. It is a principal part enlarged view of the intake port which shows other embodiment. It is a principal part enlarged view of the intake port which shows other embodiment. (A) (b) is a principal part enlarged view of the intake port which shows other embodiment. (A) is a longitudinal sectional view schematically showing the inside of the engine, and (b) is a front sectional view of the intake port.

  Embodiments of the present invention will be described with reference to the drawings. The arrangement of the combustion chamber 3 of the engine and the shape of the intake port 5 are shown in FIGS. The details of the entire cylinder 1 and the intake port 5 are shown in FIG.

  In these drawings, members and means directly related to the present invention are mainly shown, and other members and the like are not shown. Although only one cylinder 1 is shown in the drawing, the engine may be a single cylinder or a multi-cylinder having a plurality of cylinders.

  The engine of this embodiment is a four-cycle gasoline engine for automobiles. A piston 2 is accommodated in the cylinder 1 of the engine. A combustion chamber 3 is formed by the inner peripheral wall 3a of the cylinder bore, the upper surface of the piston 2, and the like. An intake port 5 for sending intake air into the combustion chamber 3 of each cylinder, an exhaust port 7 drawn out from the combustion chamber 3, a fuel injection device 9 for injecting fuel into the combustion chamber 3, and the like are provided. An ignition device is provided at the top of the combustion chamber 3.

  The engine of this embodiment is a four-valve engine, and includes two intake ports 5 connected to the intake side of the combustion chamber 3 and two exhaust ports 7 connected to the exhaust side of the combustion chamber 3. As shown in FIG. 2, the intake port 5 branches into two passages before the combustion chamber 3. Although not shown, the exhaust port 7 also branches into two passages before the combustion chamber 3.

  However, the number of intake ports 5 and exhaust ports 7 can be freely set according to specifications. The number of intake ports 5 and exhaust ports 7 may be one, two, or more, for example.

  An intake valve hole 5 a that is an opening to each combustion port 3 of each intake port 5 is opened and closed by an intake valve 6. Further, the exhaust valve hole 7 a that is an opening to each combustion port 3 of each exhaust port 7 is opened and closed by the exhaust valve 8. At this time, the intake valve 6 and the exhaust valve 8 are brought into contact with and separated from an annular seat ring 20 provided in a region facing the combustion chamber 3 of the intake port 5 and the exhaust port 7 respectively.

  The intake valve 6 and the exhaust valve 8 open and close the intake valve hole 5a and the exhaust valve hole 7a at a predetermined timing by the rotation of a camshaft provided on the cylinder head 4 side. The shaft portions of the intake valve 6 and the exhaust valve 8 are drawn out from the shaft insertion portions opened on the inner surfaces of the intake port 5 and the exhaust port 7 to the camshaft side in the cylinder head 4. As shown in FIG. 8B, the shaft insertion portion 5b of the intake port 5 is opened to the bent portion 5c located upstream of the intake valve hole 5a in the intake port 5, or just upstream of the bent portion 5c. doing.

  As shown in FIGS. 1 and 3, the seat ring 20 includes a valve abutting portion 21 that expands from the rear side toward the combustion chamber side so that the intake valve 6 abuts, and a rear side of the valve abutting portion 21. And a throat portion 22 that is provided on the portion side and expands from the back side toward the valve contact portion 21 side.

  The center o2 (center line p2) of each intake valve 6 in the two intake ports 5 is more eccentric to the exhaust port 7 side than the center o1 (center line p1) of the inner surface 24 of the flow path of the seat ring 20. Further, the center o2 (center line p2) of each intake valve 6 in the two intake ports 5 passes through the center o1 (center line p1) of the inner surface of the flow path of the seat ring 20, and the inner peripheral wall of the cylinder bore constituting the combustion chamber 3 3a is eccentric to the same side across the intake and exhaust parallel lines E1 and E2 parallel to the intake and exhaust center line A connecting the intake side center D and the exhaust side center E. In FIG. 1, the center o <b> 2 of each intake valve 6 is eccentric to the upper side, which is the same side, with intake / exhaust parallel lines E <b> 1 and E <b> 2 passing through the center o <b> 1 of the inner surface of the flow path of the seat ring 20.

  Here, the intake / exhaust center line A is a line connecting the intake side center D and the exhaust side center C of the inner peripheral wall 3a of the cylinder bore in a plan view of the combustion chamber 3. Here, the intake side center D is the midpoint between the centers o1 of the inner surfaces 24 of the flow paths in the two intake valve holes 5a, and the exhaust side center C is between the centers of the inner surfaces of the flow paths in the two exhaust valve holes 7a. Is the middle point. That is, the intake / exhaust center line A is the direction in which the center line in the width direction, which is the center line with respect to the width W (see FIG. 2) in plan view of the intake port 5, that is, the axis x of the cylinder bore constituting the combustion chamber 3. This is a direction connecting the intake side and the exhaust side with the gap interposed therebetween, and is also a direction orthogonal to the axial direction B of the crankshaft of the engine in plan view.

  Due to the eccentricity of the distance w (see FIG. 1) between the centers, the throat portion 22 of the seat ring 20 connects the center o2 of the intake valve 6 and the center o1 of the inner surface of the flow path of the seat ring 20 to each other. An eccentric intake port in which the front end side near the axis x of the cylinder bore along the lines F1 and F2, that is, the side where the center o2 of the intake valve 6 is eccentric (eccentric side) is formed relatively deeper than the others. It is composed.

  Here, in this embodiment, both of the two intake ports 5 are eccentric intake ports. Further, as described above, the center o2 of the intake valve 6 in each eccentric intake port is eccentric to one side that is the same side across the corresponding intake / exhaust parallel lines E1 and E2. By adopting such two eccentric intake ports in the same direction, the flow of intake air along the eccentric direction lines F1 and F2 is strengthened, and the arc direction of the swirl flow and the inflow direction of intake air from the intake port 5 are brought closer to each other. be able to. Thereby, the flow of the intake air in the combustion chamber 3 in the swirl direction can be promoted, and the swirl flow in the fuel chamber 3 can be strengthened. The eccentric intake port may be a part or all of the intake ports 5 provided in each cylinder 1. When only one intake port 5 is provided, the one intake port is set as an eccentric intake port.

  Further, in this embodiment, of the two eccentric intake ports, the eccentric direction line F1 and the intake / exhaust parallel line E1 in the eccentric intake port on one side located relatively downstream of the swirl flow shown in the upper side of FIG. Is set to be smaller than the angle α2 formed by the eccentric direction line F2 and the intake / exhaust parallel line E2 in the eccentric intake port on the other side, which is positioned relatively upstream of the swirl flow shown below. . For this reason, the flow t of intake air from the upstream intake valve hole 5a shown in the lower side of the figure is unlikely to hinder the flow of intake air s from the downstream intake valve hole 5a shown in the upper side of the figure. Yes. The flow of intake air s from the intake valve hole 5a on one side, that is, the downstream side (upper side in FIG. 2), where the center o2 of the intake valve 6 is far from the axis x of the cylinder bore, and the center o2 of the intake valve 6 is the axis of the cylinder bore. This is because the formation of the swirl flow u in the combustion chamber 3 is more greatly affected than the intake air flow t from the intake valve hole 5a on the other side close to the center x, that is, the upstream side (lower side in FIG. 2). In other words, it is effective in strengthening the swirl flow u that α1 <α2 and merging the flows s and t in the drawing on the upstream side.

  Here, as long as the flow of the swirl flow generated by the intake from the eccentric intake port on one side is not significantly disturbed, the angle α1 is made equal to the angle α2, or conversely, the angle α1 is made larger than the angle α2. Is also possible.

  The throat portion 22 is processed as follows. It is assumed that the seat ring 20 before processing is press-fitted in advance to a portion of the intake port 5 facing the combustion chamber 3 and is fixed to the intake port 5.

  As shown in FIG. 4A, the throat cutter A is made to enter a predetermined amount into the intake port 5 along the axial center coinciding with the center line p2 of the intake valve 6. The inner surface of the seat ring 20 is shaved by rotating the throat cutter A around the center line p2. Depending on the specifications, the throat portion 22 may be continuously processed from the inner surface of the seat ring 20 to the inner surface of the intake port 5. By processing the throat cutter A, a throat portion 22 made of a conical surface or a spherical surface is formed on the inner surface of the seat ring 20 or on the inner surface of the seat ring 20 and the inner surface of the intake port 5.

  The valve contact portion 21 is processed as follows. After the throat cutter A is removed, as shown in FIG. 4B, the seat cutter B is made to enter a predetermined amount into the seat ring 20 along the axis that coincides with the center line p2 of the intake valve 6. The inner surface of the seat ring 20 is shaved by rotating the sheet cutter B around the center line p2. By processing the seat cutter B, a valve contact portion 21 made of a conical surface or a spherical surface is formed on the inner surface of the seat ring 20.

  The throat portion 22 may be processed before the valve contact portion 21, or the valve contact portion 21 may be processed before the throat portion 22.

  FIG. 3 shows details of the intake port 5 and the seat ring 20. The symbol r1 shown in FIG. 3 indicates the radius of the flow path of the seat ring 20. The symbol o1 indicates the center of the seat ring (the center of the inner surface 24 of the flow path of the seat ring 20). Moreover, the symbol r2 in the figure indicates the radius of the outermost diameter portion of the valve contact portion 21. The symbol o2 indicates the valve center (center of the shaft portion of the intake valve 6). The symbol t0 is the thickness in the radial direction of the seat ring 20 that extends from the outer surface 23 of the seat ring 20 to the inner surface 24 of the flow path except for the throat portion 22 and the valve contact portion 21. In this embodiment, the wall thickness t0 is constant over the entire circumference.

  As described above, in the intake port structure in which the seat ring 20 includes the valve contact portion 21 with which the intake valve 6 contacts and the throat portion 22 on the back side of the valve contact portion 21, Since the center line p1 is eccentrically arranged on the front end side along the eccentric direction lines F1 and F2 with respect to the center line p2 of the flow path of the seat ring 20, the throat portion 22 extends along the eccentric direction lines F1 and F2. The front end side closer to the cylinder bore axis x along the eccentric direction lines F1 and F2 includes the rear end side far from the cylinder bore axis x along the eccentric direction lines F1 and F2. It can be formed deeper to the back side than other parts.

  In FIG. 3, symbol L <b> 21 a is the depth of the valve contact portion 21 on the front end side (the length in the busbar direction; the same applies hereinafter). Symbol L21b is the depth of the valve contact portion 21 on the rear end side. The depth of the valve abutting portion 21 is preferably in a relationship of L21a = L21b as in this embodiment in order to make the contact pressure with the intake valve 6 uniform over the entire circumference.

  Reference sign L22a is the depth of the throat portion 22 on the front end side (the length in the busbar direction; the same applies hereinafter). Reference sign L22b is the depth of the throat portion 22 on the rear end side. The depth of the throat portion 22 is preferably in a relationship of L22a> L22b.

  By adopting such a shape for the throat portion 22, it is possible to smoothly guide the intake air in the direction of the swirl flow along the inner peripheral wall 3 a of the combustion chamber 3 on the front end side along the eccentric direction lines F 1 and F 2. By suppressing the separation of the intake air from the inner surface of the intake port 5 on the rear end side along the eccentric direction lines F1 and F2, the tumble ratio can be improved. For this reason, the disturbance of the intake air in the fuel chamber 3 can be enhanced without complicating the structure.

  Further, since the center line p2 of the intake valve 6 is eccentrically arranged on the front end side along the eccentric direction lines F1 and F2 with respect to the center line p1 of the flow path of the seat ring 20, the throat portion 22 and the valve contact with each other The throat cutter A and the seat cutter B for processing the portion 21 can be constructed in a state of being arranged coaxially with the center line p2 of the intake valve 6, and the work can be performed easily and with high accuracy.

  3, the inner surface of the intake port 5 (hereinafter referred to as the seat ring upstream portion 30) continuous to the upstream side of the inner surface of the seat ring 20 is a bottom view from the combustion chamber 3 side, that is, In the axial direction of the seat ring 20 from the combustion chamber 3 side, that is, in a plan view along the direction of the center line p2 of the inner surface 24 of the flow path, on the rear end side along the eccentric direction lines F1 and F2, An inner surface matching portion 32 that is flush with the inner surface is provided. In this embodiment, the rear end portion 31 d in the figure corresponds to the inner surface matching portion 32.

  Further, in the other part of the seat ring upstream portion 30, that is, in the plan view, along the eccentric direction lines F1 and F2, the side portions on both sides connecting the front end side and the front end side and the rear end side thereof, An overhanging portion 31 that protrudes inward from the inner surface of the seat ring 20 is provided. In this embodiment, the front end portion 31 c and the side portions 31 a and 31 b in FIG. And the cross-sectional shape of the seat ring upstream portion 30 is so-called that the maximum diameter in the front-rear direction connecting the front end portion 31c and the rear end portion 31d is set larger than the maximum diameter in the width direction orthogonal thereto. It has an oval shape.

  Due to the overhanging portion 31, the cross-sectional area of the flow path of the seat ring upstream portion 30 becomes smaller than the cross-sectional area of the flow path of the seat ring 20. Thereby, the flow velocity of the intake air into the combustion chamber 3 can be further increased, and the intake air can be promptly guided in the direction along the eccentric direction lines F1 and F2.

  Here, in the upstream portion 30 of the seat ring, the protruding portion 31 is not provided at the rear end portion 31d far from the axis x of the cylinder bore. The overhanging portion 31 is provided at a place excluding the rear end portion 31d. Thereby, while ensuring the flow rate of the intake air on the side close to the inner surface 3a of the combustion chamber 3, the flow path can be narrowed on the other portion, that is, the side where the overhanging portion 31 is provided to increase the flow velocity of the intake air. It is possible to secure the flow rate at the rear end 31d and improve the flow velocity on the other side.

Here, the seat ring upstream portion 30, that is, the inner surface of the intake port 5 continuous to the upstream side of the inner surface of the seat ring 20 is the inner surface of the intake port 5 made of a metal such as a casting. It means the part located directly above. The overhanging portion 31 is provided to reduce the cross-sectional area of the flow path in the intake port 5.
For this reason, even if the shaft insertion portion 5 b that supports the shaft portion of the intake valve 6 has a portion protruding from the inner surface of the intake port 5, it does not correspond to the overhang portion 31. The seat ring upstream portion 30 is on the combustion chamber 3 side with respect to the shaft insertion portion 5 b and is a portion directly above the seat ring 20. Further, even though the inner surface of the bent portion 5c can be seen from the inner surface of the seat ring 20 in the plan view, the inner surface of the bent portion 5c is not intended to reduce the cross-sectional area of the flow path. It does not fall under part 31. The seat ring upstream portion 30 is also a portion where the cross-sectional area of the flow path of the intake port 5 gradually expands toward the combustion chamber 3.

  In addition, as a modified example in which the position and shape of the projecting portion 31 are different, for example, in the plan view, the inner end matching portion 32 is provided on the rear end portion 31d and the front end portion 31c side, and the projecting portions 31a, 31b on both sides A configuration including the portion 31 can also be adopted. Further, the protruding portion 31 may be provided only in one of the side portions 31 a and 31 b, and the other side portion may be the inner surface matching portion 32.

  In any case, when the overhanging portion 31 is provided in the seat ring upstream portion 30, the cross-sectional shape of the seat ring upstream portion 30 is an eccentric direction between the center line p2 of the intake valve 6 and the center line p1 of the flow path of the seat ring 20 It is desirable that the inner diameter of the inner surface, that is, the maximum diameter in the front-rear direction connecting the front end side and the rear end side be set larger than the maximum diameter in the width direction connecting the side portions on both sides.

  The intake port 5 including the seat ring upstream portion 30 is manufactured together with the cylinder head 4 by casting. Since the cross-sectional shape of the seat ring upstream portion 30 is not a perfect circle due to the presence of the overhang portion 31 and the inner surface matching portion 32, the casting mold at the time of casting has such a shape, or after casting The member is cut by a three-dimensional machining center or the like.

  When machining with the throat cutter A, it is desirable to machine the seat ring upstream portion 30 simultaneously with the machining of the seat ring 20 and connect them with a smooth surface. When the seat ring upstream portion 30 and the inner surface of the seat ring 20 are smoothly connected, the processing with the throat cutter A may be performed only on the seat ring 20.

  Further, in this embodiment, in both of the two eccentric intake ports, in the plan view, the rear end portion 31d is provided with the inner surface matching portion 32, and the protruding portion 31 is provided on the front end portion 31c and the side portions 31a and 31b on both sides. However, the arrangement of the inner surface matching portion 32 and the overhang portion 31 may be different between the two eccentric intake ports.

  For example, in the eccentric intake port on one side relatively downstream of the swirl flow shown in the upper side of FIG. 2, the rear end portion 31d includes an inner surface matching portion 32 in the plan view, and the front end portion 31c and The side portions 31a and 31b are provided with an overhanging portion 31, and the lower side eccentric intake port located relatively upstream of the swirl flow shown on the lower side has an inner surface on the front end portion 31c in the plan view. It is good also as a structure provided with the protrusion part 31 in the rear end part 31d and the side parts 31a and 31b of both sides provided with the coincidence part 32. In each of these examples, a modification in which the side portions 31a and 31b on both sides are the inner surface matching portions 32 is also conceivable.

  Another embodiment is shown in FIG. In this embodiment, the configuration of the seat ring upstream portion 30 is basically the same as that of the above-described embodiment, and in the plan view along the axial direction of the seat ring 20 from the combustion chamber 3 side, the eccentric direction line F1, An inner surface matching portion 32 that is flush with the inner surface of the seat ring 20 is provided on the rear end side along F2. In this embodiment, the rear end portion 31 d of FIG. 5 corresponds to the inner surface matching portion 32.

  Further, the other portion of the seat ring upstream portion 30, that is, the side portions 31 a on both sides connecting the front end side and the front end side and the rear end side along the eccentric direction lines F 1 and F 2 in the plan view, An overhanging portion 31 that protrudes inward from the inner surface of the seat ring 20 is provided in 31b. In this embodiment, the front end portion 31 c and the side portions 31 a and 31 b in FIG. The cross-sectional shape of the entire seat ring upstream portion 30 is a so-called oval shape in which the maximum diameter in the front-rear direction connecting the front end side and the rear end side is set larger than the maximum diameter in the width direction orthogonal thereto. The same is true.

  Although the side portions 31a and 31b are linear inner surfaces connecting the rear end portion 31d and the front end portion 31c, the side portions 31a and 31b may be formed in a gentle arc shape.

  Also in this embodiment, as described with reference to FIG. 1, the center o2 of the intake valve 6 passes through the center o1 of the inner surface of the flow path of the seat ring 20, and the inner peripheral wall 3a of the cylinder bore constituting the combustion chamber 3 Between the intake and exhaust parallel lines E1 and E2 parallel to the intake and exhaust center line A connecting the intake side center D and the exhaust side center C, and is eccentric to the downstream side of the swirl flow (one side shown on the upper side in the figure). The point is similar.

  As shown in FIG. 5, the outer surface 23 of the seat ring 20 and the inner surface 24 of the flow path are circular in plan view. Symbol r1 shown in FIG. 5 indicates the radius of the flow path. The symbol r2 indicates the radius of the outer surface 23. Here, with respect to the center line p2 of the outer surface 23 of the seat ring 20, the center line p1 of the inner surface 24 of the flow path is arranged eccentrically toward the rear end side along the eccentric direction lines F1 and F2.

  The center line of the intake valve 6 coincides with the center line p2 of the outer surface 23 of the seat ring 20. For this reason, the center line p2 of the intake valve 6 is arranged eccentric to the front end side, that is, the exhaust side along the eccentric direction lines F1 and F2 with respect to the center line p1 of the inner surface 24 of the flow path of the seat ring 20. Will be. In the following, the center line of the intake valve 6 is denoted by reference sign p2 similarly to the center line p2 of the outer surface 23 of the seat ring 20.

  Reference numeral o1 in FIG. 5 indicates the center of the inner surface 24 of the flow path of the seat ring 20. Further, the symbol o2 in the figure indicates the center of the outer surface 23 of the seat ring 20 (coincident with the center of the shaft portion of the intake valve 6). The symbol t1 indicates the thickness of the maximum thickness portion in the radial direction of the seat ring 20 extending from the outer surface 23 of the seat ring 20 to the inner surface 24 of the flow passage excluding the throat portion 22 and the valve contact portion 21 on the front end side. It is thick. Reference numeral t2 denotes a maximum thickness portion in the radial direction of the seat ring 20 extending from the outer surface 23 of the seat ring 20 to the inner surface 24 of the flow passage excluding the throat portion 22 and the valve contact portion 21 on the rear end side. It is thick. This thickness has a relationship of t1> t2.

  As described above, in the intake port structure in which the seat ring 20 includes the valve contact portion 21 with which the intake valve 6 contacts and the throat portion 22 on the deeper side than the valve contact portion 21, The center line p2 of the outer surface 23 that is circular in plan view, that is, the center line p2 of the intake valve 6 is toward the front end side that is close to the axis x of the cylinder bore with respect to the center line p1 of the inner surface 24 of the circular channel in plan view. Since the throat portion 22 is arranged eccentrically, the throat portion 22 can be formed deeper on the front end side than on the rear end side farther away along the eccentric direction lines F1 and F2.

  In FIG. 5, symbol L <b> 21 a is the depth of the valve contact portion 21 on the front end side (the length in the busbar direction; the same applies hereinafter). Symbol L21b is the depth of the valve contact portion 21 on the rear end side. The depth of the valve abutting portion 21 is preferably in a relationship of L21a = L21b as in this embodiment in order to make the contact pressure with the intake valve 6 uniform over the entire circumference.

  Reference sign L22a is the depth of the throat portion 22 on the front end side (the length in the busbar direction; the same applies hereinafter). Reference sign L22b is the depth of the throat portion 22 on the rear end side. The depth of the throat portion 22 is preferably in a relationship of L22a> L22b.

  Yet another embodiment is shown in FIG. In FIG. 6, the configuration of the seat ring 20 is the same as in each of the above-described embodiments. The throat portion 22 is moved further toward the back side on the front end side than the rear end side far along the eccentric direction lines F1 and F2. The point which forms deeply is the same. The center o2 of the intake valve is more eccentric to the exhaust port side than the center o1 of the inner surface of the seat ring 20 and passes through the center o1 of the inner surface of the seat ring 20 to the intake side center D and the exhaust side center of the inner peripheral wall 3a of the cylinder bore. Such a configuration is obtained by decentering to one side across the intake and exhaust parallel lines E1 and E2 parallel to the intake and exhaust center line A connecting C.

  In addition, the seat ring upstream portion 30 includes an inner surface matching portion 32 at the rear end portion 31d along the eccentric direction lines F1 and F2, and a protruding portion 31 at the front end portion 31c and the side portions 31a and 31b. This is the same as the example. The same is true in that each of the rear end portion 31d and the front end portion 31c includes an arc-shaped portion around the axis of the seat ring 20. The side portions 31a and 31b are also the same in that they are linear inner surfaces connecting the rear end portion 31d and the front end portion 31c.

  In this example, the radius rd of the arc-shaped portion of the rear end portion 31d is set larger than the radius rc of the arc-shaped portion of the front end portion 31c. As described above, it is effective to secure the flow rate on the rear end side by relatively increasing the radius on the rear end portion 31d side, and it is effective to relatively reduce the radius on the front end portion 31c side. It is effective for securing the flow velocity at

  In this way, when the front end portion 31c is provided with the overhanging portion 31, the maximum projecting lengths a and b from the inner surface of the seat ring 20 at the overhanging portion 31 of the side portions 31a and 31b are the same as those of the front end portion 31c. It is desirable to set it to be longer than the maximum projecting length c from the inner surface 24 of the seat ring 20 at the overhanging portion 31. A reduction amount of the channel cross-sectional area for improving the flow velocity can be ensured at the side portions 31a and 31b larger than the front end portion 31c. This effect is the same in the above-described embodiments.

  Yet another embodiment is shown in FIG. In FIG. 7A, the configuration of the seat ring 20 is similar to the above-described embodiments in that the throat portion 22 is located more deeply on the front end side than the rear end side along the eccentric direction lines F1 and F2. It is deeply formed on the side.

  In this aspect, the inner surface matching portion 32 is provided on the rear end portion 31d side in the plan view. Moreover, the overhang | projection part 31 is provided in the front-end part 31c and the side parts 31a and 31b of both sides. However, the projecting portions 31 of the side portions 31a and 31b are not linear, and are continuous with the arc-shaped projecting portion 31 of the front end portion 31c only at a portion closer to the front end than the center o1 of the inner surface 24 of the seat ring 20. Similarly, an arcuate overhanging portion 31 is provided. The arc-shaped projecting portions 31 of the side portions 31a and 31b and the arc-shaped projecting portion 31 of the front end portion 31c are concentric and continuous circles having the same radius rc. It is good. Further, the area of the projecting portion 31 may be increased by making the radius rc of the projecting portion 31 smaller than the radius rd of the arcuate inner surface on the rear end portion 31d side.

  Yet another embodiment is shown in FIG. In this aspect, the inner surface matching part 32 is provided in the rear end part 31d and the front end part 31c. The overhanging portion 31 is provided on the side portions 31a and 31b on both sides. In this embodiment as well, the cross-sectional shape of the seat ring upstream portion 30 is a so-called oval in which the maximum diameter in the front-rear direction connecting the front end side and the rear end side is set larger than the maximum diameter in the width direction perpendicular thereto. Shape.

  In these embodiments, the configuration of the present invention has been described by taking a four-cycle gasoline engine for automobiles as an example. However, the present invention can also be applied to a two-cycle gasoline engine, a diesel engine, various other uses, and various engines. .

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 3 Combustion chamber 4 Cylinder head 5 Intake port 6 Intake valve 7 Exhaust port 8 Exhaust valve 9 Fuel injection apparatus 20 Seat ring 21 Valve contact part 22 Throat part 23 Outer surface 24 Inner surface 30 Seat ring upstream part 31 Overhang part 32 Inner surface matching part

Claims (6)

An intake port connected to the intake side of the combustion chamber of the engine, an exhaust port connected to the exhaust side of the combustion chamber of the engine, and an annular seat provided in a region facing the combustion chamber of the intake port and the exhaust port A ring, and an intake valve and an exhaust valve that are in contact with and away from the seat ring,
The center of the intake valve in the intake port is eccentric to the exhaust port side than the center of the inner surface of the seat ring, and passes through the center of the inner surface of the seat ring, and the intake of the inner peripheral wall of the cylinder bore constituting the combustion chamber Eccentric to either side across the intake / exhaust parallel line parallel to the intake / exhaust center line connecting the center of the side and the exhaust side center,
The throat portion of the seat ring includes an eccentric intake air in which an eccentric side of the center of the intake valve is formed relatively deeper than the other along an eccentric direction line connecting the center of the intake valve and the center of the inner surface of the seat ring. Configured the port,
In plan view along the axial direction of the seat ring in the eccentric intake port, the cross-sectional area of the flow path formed by the inner surface of the intake port that is continuous upstream of the inner surface of the seat ring is the inner surface of the seat ring. An intake port structure of an engine that is set smaller than a cross-sectional area of a flow path formed by A plurality of the intake ports are provided, and the plurality of intake ports serve as the eccentric intake ports, and the centers of the intake valves in the eccentric intake ports are on the same side across the corresponding intake / exhaust parallel lines. The intake port structure for an engine according to claim 1, wherein the intake port structure is eccentric. Among the plurality of eccentric intake ports, the angle formed by the eccentric direction line and the intake / exhaust parallel line in the eccentric intake port on one side where the center of the intake valve is far from the axis of the cylinder bore is the eccentricity on the other side. The engine intake port structure according to claim 2, wherein the intake port structure is set smaller than an angle formed by the eccentric direction line and the intake / exhaust parallel line in the intake port. The inner surface of the intake port continuous to the upstream side of the inner surface of the seat ring in the eccentric intake port is rearward from the axis of the cylinder bore along the eccentric direction line in a plan view along the axial direction of the seat ring. An end surface is provided with an inner surface matching portion that is flush with the inner surface of the seat ring, and another portion is provided with an overhanging portion that protrudes inward from the inner surface of the seat ring, and the flow path at the place where the overhanging portion is located The engine intake port structure according to any one of claims 1 to 3, wherein a cross-sectional area of the engine is smaller than a cross-sectional area of the flow path of the seat ring. Among the plurality of eccentric intake ports, the inner surface of the intake port that is continuous with the upstream side of the inner surface of the seat ring in the eccentric intake port on one side far from the axis of the cylinder bore is the seat ring. In a plan view along the axial direction of the cylinder, a rear end side far from the axial center of the cylinder bore along the eccentric direction line is provided with an inner surface matching portion flush with the inner surface of the seat ring, and the cylinder bore along the eccentric direction line A projecting portion projecting inward from the inner surface of the seat ring on the front end side close to the axial center of the seat ring, and the cross-sectional area of the flow path at the location where the projecting portion is present is made smaller than the cross-sectional area of the flow path of the seat ring ,
The inner surface of the intake port that is continuous with the upstream side of the inner surface of the seat ring in the eccentric intake port on the other side is an axial center of the cylinder bore along the eccentric direction line in a plan view along the axial direction of the seat ring. A projecting portion that protrudes inward from the inner surface of the seat ring on the rear end side that is far from the axial center of the cylinder bore along the eccentric direction line. 4. The engine intake port structure according to claim 2, wherein a cross-sectional area of a flow path at a portion where the projecting portion is provided is smaller than a cross-sectional area of the flow path of the seat ring. The inner surface of the intake port continuous to the upstream side of the inner surface of the seat ring in the eccentric intake port has a front end side close to the axis of the cylinder bore along the eccentric direction line and an axial center of the cylinder bore along the eccentric direction line. The intake port structure for an engine according to any one of claims 1 to 5, wherein a maximum diameter in a front-rear direction connecting a rear end side far from the center is set larger than a maximum diameter in a width direction orthogonal thereto.

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