JP4707641B2 - Intake device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake device for an internal combustion engine, and more specifically, when intake air flows from an intake passage toward a cylinder hole along an outer surface of an intake valve during an intake stroke of the internal combustion engine, The present invention relates to an intake device for an internal combustion engine that causes a vortex to be generated at a boundary portion with an outer surface of an intake valve so that the flow of intake air is smooth.

  Conventionally, an internal combustion engine is disclosed in Patent Document 1 below. According to this publication, an internal combustion engine includes a cylinder protruding from a crankcase that supports a crankshaft, a cylinder head that is attached to a protruding end of the cylinder and closes the cylinder hole, and is axially disposed with respect to the cylinder hole. A piston inserted so as to be slidable and a connecting rod for interlockingly connecting the piston and the crankshaft are provided.

  As an intake device for the internal combustion engine, an intake passage is formed on one side of the cylinder head to communicate the outside with the cylinder hole. In addition, an exhaust passage for communicating the inside of the cylinder hole to the outside is formed on the other side of the cylinder head. There is provided a poppet type intake valve capable of opening and closing the downstream end opening of the intake passage that opens into the cylinder hole. Also, a poppet type exhaust valve is provided that can open and close the upstream end opening of the exhaust passage that opens into the cylinder hole.

  The umbrella portion of the intake valve is an annular valve seat (valve seat) in which a valve surface (valve face) formed on the outer peripheral surface of the umbrella portion is formed at the opening edge of the downstream end opening of the intake passage. The downstream end opening can be opened and closed by separating from and contacting.

In the intake and exhaust strokes due to the driving of the internal combustion engine, by the opening and closing valve operations of the intake and exhaust valves, outside air passes through the intake passage and enters the cylinder hole as intake air for combustion. On the other hand, the combustion gas generated by this combustion is discharged to the outside through the exhaust passage as exhaust.
JP-A-8-247016

  Incidentally, the outer surface of the intake valve is usually machined smoothly as a whole. For this reason, when the intake valve is opened during the intake stroke of the internal combustion engine and intake air is sucked into the cylinder hole through the intake passage, the intake air is taken from the outer surface of the umbrella portion on the intake passage side. Peeling is suppressed, and it tends to flow while being largely bent along the outer surface of the umbrella.

  However, the flow that bends greatly as described above inhibits the smooth flow of the intake air from the intake passage into the cylinder hole, which is a cause of hindering the improvement of the charging efficiency in the internal combustion engine. This is not preferable in terms of engine performance.

  The present invention has been made paying attention to the above situation, and the object of the present invention is to make the intake air flow smoothly from the intake passage into the cylinder hole in the intake stroke of the internal combustion engine. It is to improve the charging efficiency of the internal combustion engine.

According to the first aspect of the present invention, the valve surface 19 of the umbrella portion 17 is separated from the annular valve seat 21 formed at the opening edge of the downstream end opening 10 of the intake passage 8 that opens into the cylinder hole 3. A poppet-type intake valve 11 that can open and close the downstream end opening 10 in contact therewith is provided , and the intake valve 11 is positioned on the same axis 16 as the umbrella portion 17 so that the downstream end opening 10 is opened. In an intake device for an internal combustion engine comprising a valve rod 18 that integrally protrudes from the umbrella portion 17 so as to penetrate ,
A concave portion 26 is formed on the outer surface 25 of the umbrella portion 17 on the intake passage 8 side of the valve surface 19, and the concave portion 26 is viewed in a cross section of the concave portion 26 in a side view of the intake valve 11 (FIG. 1). When an imaginary line 31 that passes through the lowest part and is parallel to the axis 16 is set, among the inner surfaces of the recessed part 26, the inner surface 32 on the valve face 19 side of the recessed part 26 and the imaginary line 31 Is made an acute angle, an intersection angle θ2 between the other inner surface 33 on the valve stem 18 side and the imaginary line 31 with respect to the bottom of the recess 26 is made an acute angle, and the other inner surface 33 is made to be the recess. 26 is linearly extended from the bottommost portion of the valve 26 toward the valve stem 18 side, and then connected to the outer surface of the valve stem 18 via an arc concave surface .

  According to a second aspect of the present invention, in addition to the first aspect of the invention, the concave portion 26 is formed in a groove shape extending in the circumferential direction of the intake valve 11 along the vicinity of the valve surface 19 of the umbrella portion 17.

  In this section, the reference numerals appended to the above terms are not to be construed as limiting the technical scope of the present invention to the section “Example” described later or the contents of the drawings.

  The effects of the present invention are as follows.

The invention according to claim 1 is characterized in that the valve surface of the umbrella portion is separated from and contacts the annular valve seat formed at the opening edge of the downstream end opening of the intake passage opening toward the inside of the cylinder hole. In an intake device of an internal combustion engine having a poppet type intake valve that can open and close
A concave portion is formed on the outer surface of the umbrella portion closer to the intake passage than the valve surface.

  For this reason, when the intake air flows toward the inside of the cylinder hole, a vortex is generated at the boundary portion between the intake air and the outer surface of the umbrella portion due to the concave portion formed on the outer surface. The vortex causes the intake air to be separated from the outer surface of the umbrella portion and directed into the cylinder hole, so that the intake air flows more linearly toward the cylinder hole. .

  Therefore, the intake air flows more smoothly than the conventional technique in which the separation of the intake air from the outer surface of the umbrella portion is suppressed and the air flows while bending largely along the outer surface of the umbrella portion. To be made. As a result, the charging efficiency of the internal combustion engine is improved and the engine performance is improved.

  According to a second aspect of the present invention, the recess has a groove shape extending in the vicinity of the valve surface of the umbrella portion along the circumferential direction of the intake valve.

  For this reason, a vortex arises more reliably in the outer edge part of the outer surface of the umbrella part in the vicinity of the said valve surface. Therefore, the intake air flowing toward the inside of the cylinder hole is separated from the outer surface of the umbrella portion and the valve surface by the vortex, and is allowed to flow with a small fluid resistance. That is, the intake air flows more smoothly. As a result, the charging efficiency of the internal combustion engine is further improved, and the engine performance is more reliably improved.

  The intake device for an internal combustion engine according to the present invention is configured to improve the charging efficiency of the internal combustion engine by allowing the intake air to smoothly flow from the intake passage into the cylinder hole during the intake stroke of the internal combustion engine. In order to realize the object, the best mode for carrying out the present invention is as follows.

That is, an intake device for an internal combustion engine includes a poppet type intake valve. In addition, the intake valve includes a valve rod that is positioned on the same axis as the umbrella portion and protrudes integrally from the umbrella portion so as to penetrate the downstream end opening. The valve face of the umbrella portion of the intake valve can be separated from the annular valve seat formed at the opening edge of the downstream end opening of the intake passage that opens into the cylinder hole, and the downstream end opening can be opened and closed. And A concave portion is formed on the outer surface of the umbrella portion on the intake passage side than the valve surface. Further, when the imaginary line passing through the bottom of the recess and parallel to the axis is set in the cross section of the recess in a side view of the intake valve, the innermost surface of the recess is more than the bottom of the recess. In addition, the angle of intersection between the inner surface on the valve surface side and the imaginary line is set to an acute angle, and the angle of intersection between the other inner surface on the valve stem side and the imaginary line is set to an acute angle from the bottom of the recess. The other inner surface linearly extends from the bottom of the concave portion toward the valve stem, and is connected to the outer surface of the valve stem via an arc concave surface.

  In order to explain the present invention in more detail, an embodiment thereof will be described with reference to the accompanying drawings.

  1 and 2, reference numeral 1 denotes a four-cycle internal combustion engine. The internal combustion engine 1 includes a cylinder 2 that protrudes upward from a crankcase (not shown), a cylinder head 4 that is attached to the protruding end of the cylinder 2 and closes the upper end of the cylinder hole 3 of the cylinder 2, and the cylinder A piston (not shown) that is positioned coaxially with the axial center 5 of the hole 3 and is fitted in the cylinder hole 3 so as to be slidable in the axial direction, an intake device 6, and an exhaust device 7 are provided. .

  As the intake device 6 of the internal combustion engine 1, an intake passage 8 is formed in one side portion of the cylinder head 4 so that the outside communicates with the cylinder hole 3. Further, as the exhaust device 7 of the internal combustion engine 1, an exhaust passage 9 that communicates the inside of the cylinder hole 3 to the outside is formed on the other side of the cylinder head 4. A poppet type intake valve 11 that can open and close the downstream end opening 10 of the intake passage 8 that opens toward the inside of the cylinder hole 3 is provided, and the intake valve 11 is supported by the cylinder head 4. Further, a poppet type exhaust valve 13 is provided that can open and close an upstream end opening 12 of the exhaust passage 9 that opens toward the inside of the cylinder hole 3, and the exhaust valve 13 is supported by the cylinder head 4.

  An axis 16 of the intake valve 11 is located on the axis 15 of the downstream end opening 10 of the intake passage 8. The intake valve 11 is positioned on the axial center 16, and a disc-shaped umbrella portion 17 that allows the downstream end opening 10 of the intake passage 8 to be opened and closed from the cylinder hole 3 side. And a valve rod 18 that integrally protrudes from the umbrella portion 17 so as to penetrate the downstream end opening 10. An annular valve surface (valve face) 19 centering on the axis 16 of the intake valve 11 is formed on the outer peripheral surface of the umbrella portion 17.

  On the other hand, an annular valve seat (valve seat) 21 is formed at the opening edge of the downstream end opening 10 of the intake passage 8. The valve surface 19 of the umbrella portion 17 of the intake valve 11 is separated from the valve seat 21 (solid line in FIGS. 1 and 2) and abuts (FIG. 1) by the opening / closing valve operation by the axial movement of the intake valve 11. The downstream end opening 10 can be opened and closed.

  In the intake and exhaust strokes driven by the internal combustion engine 1, external air is sucked as intake air 23 through the intake passage 8 and into the cylinder hole 3 by the on / off valve operations of the intake and exhaust valves 11 and 13. While being used for combustion, the combustion gas generated by this combustion is discharged to the outside through the exhaust passage 9 as exhaust 24.

  In the above configuration, a recess 26 is formed on the outer surface 25 of the umbrella portion 17 on the intake passage 8 side than the valve surface 19.

  Here, the outer surface of the intake valve 11 is usually machined smoothly as a whole. Therefore, in the intake stroke of the internal combustion engine 1, the intake valve 11 opens and passes through the valve gap 28 between the valve surface 19 and the valve seat 21 and sucks into the cylinder hole 3 from the intake passage 8. When the air 23 is inhaled, the intake air 23 flows while being bent largely along the outer surface 25 of the umbrella portion 17 while the separation from the outer surface 25 of the umbrella portion 17 on the intake passage 8 side is suppressed. Tend to. However, such a flow hinders the smooth flow of the intake air 23 from the intake passage 8 into the cylinder hole 3.

  Therefore, as described above, the concave portion 26 is formed on the outer surface 25 of the umbrella portion 17 on the side of the intake passage 8 with respect to the valve surface 19, so that the intake air 23 is directed toward the inside of the cylinder hole 3. When flowing through the valve gap 28, a vortex 29 is generated at the boundary portion (including the boundary layer) between the intake air 23 and the outer surface 25 of the umbrella portion 17 due to the concave portion 26 formed on the outer surface 25. The vortex 29 causes the intake air 23 to be separated from the outer surface 25 of the umbrella portion 17 and directed into the cylinder hole 3. It is made to flow more linearly.

  Therefore, the flow of the intake air 23 is higher than that of the conventional technique in which the separation of the intake air from the outer surface of the umbrella portion is controlled and the bent air flows while bending largely along the outer surface of the umbrella portion. It is made smoothly. As a result, the charging efficiency of the internal combustion engine 1 is improved, and the engine performance is improved.

  The recess 26 has a groove shape extending in the circumferential direction of the intake valve 11 along the vicinity of the valve surface 19 of the umbrella portion 17 and is continuous with the axis 16 of the intake valve 11 as a center. It is formed to have an annular shape. The recess 26 may be a discontinuous ring shape.

  For this reason, the vortex 29 is more reliably generated in each circumferential portion of the outer edge portion of the outer surface 25 of the umbrella portion 17 in the vicinity of the valve surface 19. Therefore, when the intake air 23 flows at a high flow rate toward the inside of the cylinder hole 3 through the valve gap 28 having a small gap size, the intake air 23 is separated from the outer surface 25 of the umbrella portion 17 and the valve surface 19 by the vortex 29. And is made to flow with a small fluid resistance. That is, the flow of the intake air 23 is made smoother. As a result, the charging efficiency of the internal combustion engine 1 is further improved, and the engine performance is more reliably improved.

In this embodiment, an imaginary line 31 passing through the bottom of the recess 26 and parallel to the axis 16 of the intake valve 11 is set as viewed in a cross section of the recess 26 in a side view of the intake valve 11 (FIG. 1). when, among the inner surface of the recess 26, the intersection angle θ1 of the inner surface 32 and the imaginary line 31 of the valve face 19 side from the lowest portion of the recess 26, the than the bottommost part of the concave portion 26 the valve stem 18 It is made smaller than the intersection angle θ <b> 2 between the other inner surface 33 on the side and the virtual line 31.

  Therefore, when the intake air 23 flows through the valve gap 28 toward the cylinder hole 3, a part of the intake air 23 that has flowed along the other inner surface 33 of the intake valve 11 on the axis 16 side. Tends to collide more vigorously against the inner surface 32 on the valve surface 19 side having a small intersection angle θ1, and the vortex 29 is more reliably generated around the recess 26.

  Therefore, the intake air 23 is more reliably separated from the outer surface 25 of the umbrella portion 17 by the vortex 29 and is made to flow more linearly into the cylinder hole 3. That is, the flow of the intake air 23 is made smoother. As a result, the charging efficiency of the internal combustion engine 1 is further improved, and the engine performance is more reliably improved.

  FIG. 3 is a graph of experimental results as an example in which the value of the valve lift L is set variously and the amount of each intake air 23 is measured using the conventional intake valve and the intake valve 11 of the present application. .

  Specifically, a flow rate (g / sec) of the intake air 23 is used for each set value of the valve lift L using a conventional general intake valve (conventional standard) and the intake valve 11 of the present application. It is the experimental result which measured this using fluid analysis (CFD), a Pitot tube, etc. The amount of intake air 23 is substantially proportional to the charging efficiency of the internal combustion engine 1.

  According to FIG. 3, it can be seen that the amount of intake air 23 according to the present application increases by approximately 2% with respect to the amount of intake air according to the conventional standard in the range of A of the valve lift L. That is, an improvement in filling efficiency can be expected.

  Although the above is based on the illustrated example, in the case of the intake valve 11 having a large valve bevel angle, in the recess 26, the intersection angle θ1 may be equal to the intersection angle θ2, or θ1> θ2. The recess 26 may be a U-shaped groove. Further, the recesses 26 may be formed in a hemispherical shape or the like, and may be arranged in a large number in the circumferential direction around the axis 16 with a desired diameter, or a large number of recesses 26 having a small radius may be formed randomly.

FIG. 3 is a partially enlarged view of FIG. 2. It is a partial side sectional view of an internal combustion engine. It is a graph which shows an experimental result.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Cylinder hole 4 Cylinder head 5 Shaft center 6 Intake device 8 Intake passage 10 Downstream end opening 11 Intake valve 15 Axis center 16 Axis center 17 Umbrella part 18 Valve rod 19 Valve surface 21 Valve seat 23 Intake air 25 Outer surface 26 Recess 28 Valve clearance 29 Vortex 31 Virtual line 32 Inner surface 33 Other inner surface L Valve lift θ1 Intersection angle θ2 Intersection angle

Claims (2)

Poppet type that allows opening and closing of the downstream end opening by separating the valve surface of the umbrella portion from the annular valve seat formed at the opening edge of the downstream end opening of the intake passage that opens toward the cylinder hole An intake device for an internal combustion engine, comprising an intake valve, the intake valve being located on the same axial center as the umbrella portion and having a valve rod integrally protruding from the umbrella portion so as to penetrate the downstream end opening In
A concave portion is formed on the outer surface of the umbrella portion closer to the intake passage than the valve surface, and is viewed in a cross section of the concave portion in a side view of the intake valve and passes through the bottom of the concave portion and is parallel to the axial center. When a line is set, among the inner surfaces of the recesses, the intersection angle between the inner surface on the valve surface side and the imaginary line with respect to the bottom surface of the recesses is made an acute angle, and the valve stem side with respect to the bottom surface of the recesses After making the angle of intersection between the other inner surface and the imaginary line an acute angle, and extending the other inner surface linearly from the bottom of the recess toward the valve stem, an arc concave surface is formed on the outer surface of the valve stem. An intake device for an internal combustion engine characterized by being connected via   2. The intake device for an internal combustion engine according to claim 1, wherein the recess has a groove shape extending in the circumferential direction of the intake valve along the vicinity of the valve surface of the umbrella portion.

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