JP2016169715A - Engine intake port structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further enhance a reduction effect of knocking without making the structure of an engine complex.SOLUTION: A center o2 of an intake valve 6 in a plurality of intake ports 5 is eccentric toward an exhaust port 7 from a center o1 of an inner face of a seat ring 20, and is eccentric toward a side of a shaft center x of a cylinder bore across intake/exhaust parallel lines E1, E2 parallel to an intake/exhaust center line A passing through the center o1 of the inner face of the seat ring 20 and connecting between an intake side center D and exhaust side center C of a cylindrical bore inner face 3a constituting a combustion chamber 3. 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 of the seat ring 20. Furthermore, injection center lines G1, G2 of fuel injection performed by a port injection valve 9 arranged inside the eccentric suction port is constructed to be directed to a shaft center x side of a cylinder bore rather than the center o1 of the inner face 24 of the seat ring 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an intake port structure for an engine that improves anti-knock performance.

  Engines mounted on vehicles and the like widely use exhaust gas recirculation devices that reduce the combustion temperature and reduce nitrogen oxide emissions from the engine by recirculating part of the exhaust gas to the intake passage. . Various techniques for reducing engine knock using exhaust gas recirculated to the intake passage by the exhaust gas recirculation device (hereinafter referred to as recirculation gas) have been proposed.

  For example, in Patent Document 1, a discharge port of the recirculation gas to the intake passage is installed in the vicinity of the combustion chamber, and the direction of the discharge port is set so that the recirculation gas follows the inner peripheral wall of the combustion chamber. As a result, the recirculation gas swirls on a swirl flow along the inner peripheral wall of the combustion chamber, and an annular recirculation gas layer made of active gas is formed along the inner peripheral wall in the combustion chamber. Since the ignition device is located in the center of the cylinder head, knocking is reduced by suppressing self-ignition of end gas in the vicinity of the inner peripheral wall while ensuring good ignition performance at the center of the combustion chamber.

  Further, in Patent Document 2, the operation of the valve is changed to 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 so It is possible to switch to a partial open / close mode that generates a swirl flow. The exhaust gas recirculation device returns to the combustion chamber when the direction of the exhaust port to the intake passage is set along the swirling direction of the swirl flow along the inner peripheral wall of the combustion chamber and the partial opening / closing mode of the valve is selected. An intake swirl flow containing a large amount of gas is generated, and an annular recirculation gas layer is formed along the inner peripheral wall in the combustion chamber.

JP 62-131961 A JP 2013-87628 A

  As described above, forming an annular recirculation gas layer in a portion along the inner peripheral wall in the combustion chamber is effective in reducing knocking. However, in general, in the combustion chamber of the engine, knocking called a knock starting point occurs near the inner peripheral wall near the exhaust port and at a portion located on the outer side in the circumferential direction along the inner peripheral wall from the portion where the exhaust port is interposed. There is an easy part.

  For this reason, in the technique using the swirl flow, when fuel is injected by a fuel injection valve provided in the intake port, if the fuel reaches a portion called a knock starting point, knocking occurs under a predetermined condition. It may be a cause.

  Accordingly, an object of the present invention is to more reliably suppress the occurrence of knocking.

  In order to solve the above problems, the present invention provides an intake port connected to an intake side of an engine combustion chamber and introducing intake air into the combustion chamber, an exhaust port connected to an exhaust side of the combustion chamber of the engine, An annular seat ring provided in a region of the intake port and the exhaust port facing the combustion chamber, an intake valve and an exhaust valve that contact and separate from the seat ring, and a port injection valve that injects fuel into the intake port 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 forms an inner peripheral wall of the cylinder bore. The seat ring is eccentric to the axial center side of the cylinder bore across the intake / exhaust parallel line parallel to the intake / exhaust center line connecting the intake side center and the exhaust side center The throat portion constitutes an eccentric intake port 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. An engine intake port structure is adopted in which the injection center line of fuel injection by the port injection valve in the eccentric intake port is oriented toward the axial center side of the cylinder bore rather than the center of the inner surface of the seat ring.

  At this time, the range of fuel injection by the port injection valve in the eccentric intake port is limited to a range near the axis of the cylinder bore in the flow path of the intake valve hole formed by the inner surface of the seat ring. Can be adopted.

  In each of these configurations, it is possible to employ a configuration in which a plurality of intake ports are provided across the intake / exhaust center line, and the intake ports on both sides of the intake / exhaust center line are the eccentric intake ports. .

  Further, in each of these configurations, a low concentration that introduces a low concentration combustion component gas having a lower fuel concentration or a lower oxygen concentration than the intake air containing the fuel flowing through the intake port from the introduction port that opens to the eccentric intake port. It is possible to employ a configuration in which a combustion component gas introduction device is provided, and the introduction port is opened on the inner wall of the eccentric intake port far from the intake / exhaust center line.

  The low-concentration combustion component gas introduction device is provided in the exhaust gas recirculation device that recirculates a part of the exhaust gas discharged from the combustion chamber as a low-concentration combustion component gas from the inlet into the intake port, or provided in the intake port It is possible to employ a configuration that is an air introduction device that introduces air immediately downstream of the throttle valve to be introduced into the intake port from the introduction port as a low-concentration combustion component gas.

  Alternatively, the low-concentration combustion component gas introduction device includes an exhaust gas recirculation device that recirculates the exhaust gas discharged from the combustion chamber into the intake port from the introduction port as a low-concentration combustion component gas, and low-concentration combustion of air. A configuration in which an air introduction device that introduces the component gas from the introduction port into the intake port as a component gas can be employed.

  In each of these configurations, fuel injection by the port injection valve in the eccentric intake port is performed when the intake valve opens the flow path of the intake valve hole formed by the inner surface of the seat ring in the intake stroke. It is possible to employ a configuration that is performed while directing a gap between the intake valve and the intake valve hole.

  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 It is possible to adopt a configuration in which the cross-sectional area is smaller than the 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. It is possible to adopt a configuration in which the maximum diameter in the front-rear direction connecting the rear end side far from the center is set larger than the maximum diameter in the width direction orthogonal thereto.

  In this invention, the center of the intake valve in the intake port is eccentric to 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 of the cylinder bore inner surface constituting the combustion chamber. The seat ring throat part is connected to the center of the intake valve and the center of the inner surface of the seat ring, with the intake / exhaust parallel line parallel to the center of the exhaust side being sandwiched and eccentric to the axial center side of the cylinder bore. An eccentric intake port is formed in which the eccentric side of the center of the intake valve is formed relatively deeper than the other along the eccentric direction line. Further, the injection center line of the fuel injection by the port injection valve arranged in the eccentric intake port is directed to the axial center side of the cylinder bore rather than the center of the inner surface of the seat ring. As a result, the fuel can be concentrated in the vicinity of the axial center of the cylinder bore, and the fuel can be supplied as little as possible to the portion near the inner peripheral wall of the cylinder bore. Therefore, the occurrence of knocking can be more reliably suppressed.

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 cross-sectional view schematically showing the inside of an engine provided with an exhaust gas recirculation device as a low-concentration combustion component gas introduction device, and (b) is a front cross-sectional view of an intake port. It is a top view which shows typically the engine provided with the air introduction apparatus as a low concentration combustion component gas introduction apparatus.

  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 from the combustion chamber 3, a port injection valve 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, in the present invention, the number of intake ports 5 and exhaust ports 7 can be freely set according to specifications. The number of intake ports 5 may be more as long as at least two intake ports 5 are provided. Further, the number of 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 FIG. 3, the seat ring 20 includes a valve abutting portion 21 that expands from the back side toward the combustion chamber side so that the intake valve 6 abuts, and a farther side than the valve abutting portion 21. And a throat portion 22 that extends from the back side toward the valve contact portion 21 side.

  An intake port 43 of the low-concentration combustion component gas introduction device 40 is opened in the intake port 5. The introduction port 43 is directed toward the combustion chamber 3 so that the low-concentration combustion component gas introduced is smoothly guided to the combustion chamber 3 along the flow of intake air including fuel flowing in the intake port 5. It is arranged so as to open facing.

  In this embodiment, the low-concentration combustion component gas introduction device 40 introduces a recirculation gas that is part of the exhaust gas discharged from the combustion chamber 3 through the exhaust port 7 into the intake port 5 as a low-concentration combustion component gas. The exhaust gas recirculation device 40 </ b> A is configured to recirculate from the port 43 into the intake port 5.

  As shown in FIG. 8A, the exhaust gas recirculation device 40 </ b> A sends the recirculated gas to the intake port 5 through an exhaust recirculation passage 41 </ b> A that connects the exhaust port 7 or the exhaust passage that follows it, and the intake port 5 or the intake passage that follows it. It is refluxing. An inlet passage 42A at the end of the exhaust gas recirculation passage 41A is arranged along the flow direction of the intake air of the intake port 5, and an introduction port 43A that opens into the space in the intake port 5 is provided at the end of the inlet passage 42A. Yes. An exhaust gas recirculation valve 44 provided in the middle of the exhaust gas recirculation passage 41A adjusts the amount of recirculation gas introduced.

  Further, as shown in FIG. 9, the low-concentration combustion component gas introduction device 40 uses the air (fresh air) immediately downstream of the throttle valve 45 provided in the intake port as the low-concentration combustion component gas and communicates it to the combustion chamber 3. An air introduction device 40B that introduces air into the intake port 5 from the introduction port 43B that opens to the intake port 5 may be used. As shown in FIG. 9, the air introduction device 40 </ b> B introduces air into the intake port 5 that communicates with the combustion chamber 3 through an air introduction passage 41 </ b> B that is an intake port that communicates with outside air. An introduction path 42B at the end of the air introduction passage 41B is arranged along the flow direction of the intake port 5, and an introduction port 43B that opens to the space in the intake port 5 is provided at the end of the introduction path 42B. A throttle valve 45 provided at the upstream end of the air introduction passage 41B adjusts the amount of air introduced.

  As the low-concentration combustion component gas introduction device 40, either the exhaust gas recirculation device 40A or the air introduction device 40B may be employed, or both may be used in combination.

  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 surface 3a of the cylinder bore constituting the combustion chamber 3 Both are eccentric to the axis x side of the cylinder bore across the intake / exhaust parallel lines E1, E2 parallel to the intake / exhaust center line A connecting the intake side center D and the exhaust side center C. In FIG. 1, the center o2 of each intake valve 6 is the axis x side of the cylinder bore, that is, the upper side in the figure, across the intake and exhaust parallel lines E1 and E2 passing through the center o1 of the inner surface of the flow path of the seat ring 20 respectively. The center o2 of the intake valve 6 on one side shown in FIG. 5 is eccentric to the lower side, and the center o2 of the intake valve 6 on the other side shown to the lower side in the figure is eccentric to the upper side.

  Here, the intake / exhaust center line A is a line connecting the intake side center D and the exhaust side center C of the cylinder bore inner surface 3 a 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. By adopting such two eccentric intake ports eccentric to the axial center x side, the flow of intake air along the eccentric direction lines F1 and F2 is strengthened, and the fuel is concentrated near the axial center x of the cylinder bore. It is possible to supply as little fuel as possible to a portion called a knock starting point (a portion indicated by a symbol Z in FIG. 1) along the inner peripheral wall 3a. Thereby, the knocking reduction effect can be further enhanced.

  Further, in each eccentric intake port, the injection center lines G1, G2 of the fuel injection by the port injection valve 9 provided in the intake port 5 are, as shown in FIG. 1, more than the center o1 of the inner surface of the seat ring 20. Oriented toward the axis x side of the cylinder bore

  Further, in this embodiment, the range of fuel injection by the port injection valve 9 at each eccentric intake port is set close to the axis x of the cylinder bore in the flow path of the intake valve hole 5a formed by the inner surface 24 of the seat ring 20. Limited to range.

  Also at these points, the fuel can be concentrated in the vicinity of the axial center x of the cylinder bore, and the fuel can be prevented from being supplied to the knock starting point Z along the inner peripheral wall 3a of the combustion chamber 3 as much as possible.

  The position of the inlet 43 of the low-concentration combustion component gas introducing device 40 is open to the inner wall far from the intake / exhaust center line A among the inner walls of each intake port 5. Further, in this embodiment, the introduction port 43 opens on the opposite side of the cylinder bore with the axis x between the intake and exhaust parallel lines E1 and E2. For this reason, low-concentration combustion component gases such as recirculation gas and air are quickly supplied near the knock starting point Z near the inner peripheral wall 3a of the combustion chamber 3.

  The eccentric intake ports may be part or all of the plurality of intake ports 5 provided in each cylinder 1 as long as they are arranged on both sides of the intake / exhaust center line A. Also good.

  Further, the low-concentration combustion component gas introduction device 40 may be omitted as long as knocking suppression is not hindered.

  In this embodiment, of the two eccentric intake ports, the angle α1 formed by the eccentric direction line F1 and the intake / exhaust parallel line E1 in the one-side eccentric intake port shown in the upper side of FIG. It is set to be equal to 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 located downstream of the swirl flow. For this reason, the intake air flow t from the upstream intake valve hole 5a shown in the lower side of the figure and the intake flow s from the downstream intake valve hole 5a shown in the upper side of the figure are both the axis of the cylinder bore. The vicinity of x can be aimed equally.

  Here, depending on the arrangement of the intake valve 5, the flow of the intake air, the combustion conditions, and the like, a mode in which the angle α1 is different from the angle α2 is also conceivable.

  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 forming the throat portion 22 in such a shape, the intake air is smoothly guided to the vicinity of the axis x far from the inner peripheral wall 3a of the combustion chamber 3 on the front end side along the eccentric direction lines F1 and F2. The tumble ratio can be improved by improving the performance and 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.

  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 peripheral wall 3a of the combustion chamber 3, it is possible to increase the flow velocity of the intake air by narrowing the flow path at the other portion, that is, the side where the overhanging portion 31 is provided. 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. The cross-sectional shape of the seat ring upstream portion 30 is the same as each other, but the arrangement of the inner surface matching portion 32 and the overhang portion 31 and the cross-sectional shape of the seat ring upstream portion 30 are different between the two eccentric intake ports. It may be allowed.

  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.

  In this embodiment as well, 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 intake side of the inner surface of the cylinder bore constituting the combustion chamber 3 The same is true in that it is eccentric to the axis x side of the cylinder bore across the intake / exhaust parallel lines E1, E2 parallel to the intake / exhaust center line A connecting the center D and the exhaust side center C.

  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.

  Here, the symbol 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 toward the axis x side of the cylinder bore across the intake / exhaust parallel lines E1, E2 parallel to the intake / 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 overhang portion 31, the maximum protrusion lengths a and b from the inner surface 24 of the seat ring 20 at the overhang portion 31 of the side portions 31a and 31b are the front end portion 31c. It is desirable that the overhanging portion 31 is set to be longer than the maximum projecting length c from the inner surface of the seat ring 20 to the inside. 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 the engine using the intake port structure of the engine of each of these embodiments, the fuel injection by the port injection valve 9 at the eccentric intake port is performed by the intake valve 5 formed by the inner surface 24 of the seat ring 20 in the intake stroke. It is desirable to perform control so that when the flow path of the hole 5a is opened, the flow is directed toward the gap between the intake valve 6 and the intake valve hole 5a. As a result, the injected fuel is directed to the back surface of the umbrella portion of the intake valve 6 and the gap between the back surface of the umbrella portion and the inner surface of the intake valve hole 5a, so that it is difficult to hit the inner peripheral wall 3a of the combustion chamber 3. The effect of becoming can be expected.

  The valve opening / closing operation can be controlled by an electronic control unit provided in a vehicle equipped with the engine, using a variable valve timing mechanism. The electronic control unit can also control the timing and period of fuel injection by the port injection valve 9 and the timing of fuel ignition by the ignition device.

  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 Port injection valve 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 portion 40 Low-concentration combustion component gas introduction device 43 Inlet

Claims (8)

An intake port connected to the intake side of the combustion chamber of the engine for introducing intake air into the combustion chamber, an exhaust port connected to the exhaust side of the combustion chamber of the engine, and a region facing the combustion chamber of the intake port and the exhaust port Provided with an annular seat ring, an intake valve and an exhaust valve contacting and separating from the seat ring, and a port injection valve for injecting fuel into the intake port,
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 to the inner peripheral wall of the cylinder bore constituting the combustion chamber. Eccentric to the axial side of the cylinder bore across the intake / exhaust parallel line parallel to the intake / exhaust center line connecting the intake side center 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,
An engine intake port structure in which an injection center line of fuel injection by the port injection valve in the eccentric intake port is directed to the axial center side of the cylinder bore from the center of the inner surface of the seat ring. The range of fuel injection by the port injection valve in the eccentric intake port is limited to a range near the axis of the cylinder bore in the flow path of the intake valve hole formed by the inner surface of the seat ring. The engine intake port structure described. The intake port structure for an engine according to claim 1 or 2, wherein the intake port structure has a plurality of intake ports across the intake / exhaust center line, and the intake ports on both sides of the intake / exhaust center line are the eccentric intake ports. . A low-concentration combustion component gas introduction device that introduces a low-concentration combustion component gas having a lower fuel concentration or a lower oxygen concentration than intake air including fuel flowing in the intake port from the inlet opening that opens to the eccentric intake port; 4. The intake port structure for an engine according to claim 1, wherein the introduction port opens on an inner wall of the eccentric intake port that is far from the intake / exhaust center line. 5. The low-concentration combustion component gas introduction device is provided in the exhaust gas recirculation device that recirculates a part of the exhaust gas discharged from the combustion chamber as a low-concentration combustion component gas from the inlet into the intake port, or in the intake port. 5. An engine according to claim 4, wherein air directly downstream of a throttle valve to be introduced is introduced into the intake port from the inlet as a low-concentration combustion component gas, or an exhaust recirculation device and an air inlet are used in combination. Intake port structure. The fuel injection by the port injection valve in the eccentric intake port is performed when the intake valve opens the intake valve hole passage formed by the inner surface of the seat ring in the intake stroke. The intake port structure for an engine according to any one of claims 1 to 5, wherein the intake port structure is performed while directing a gap between the two. 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 intake port structure for an engine according to any one of claims 1 to 6, wherein a cross-sectional area of the engine is set 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 claim 7, wherein the maximum diameter in the front-rear direction connecting the rear end side far from the center is set larger than the maximum diameter in the width direction orthogonal thereto.

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