JP2008240535A - Burnt gas control device by poppet valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily set a burnt gas quantity to be carried over up to an intake stroke, in a combustion control device of a four-stroke engine for holding a part of burnt gas generated by combustion up to a succeeding intake stroke, by arranging a shock absorbing chamber communicating with a combustion chamber in a poppet valve via a small diameter communicating passage. <P>SOLUTION: A substantially hemispherical recess having a deep central part is arranged on a surface opposed to the combustion chamber of a valve element. The shock absorbing chamber is arranged inside by closing its recess by a partition wall made of a heat resistant material and made in a substantially hemispherical shape of projecting in the combustion chamber direction. The inside and outside of its shock absorbing chamber are communicated by the communicating passage arranged in the partition wall. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burned gas control device suitable for a four-stage engine used in automobiles and motorcycles, and more particularly, to oxidize nitrogen generated in a combustion chamber using a poppet valve used for intake and exhaust. The present invention relates to an apparatus for suppressing the generation of objects.

  In general, as a means for suppressing nitrogen oxides generated in a combustion chamber, a so-called exhaust gas recirculation device that recirculates burnt gas in the combustion chamber to the combustion chamber is well known. Further, as a means for simplifying the configuration of the exhaust gas recirculation device, the applicant previously configured the stem 52 of the poppet valve 50 serving as an intake valve or an exhaust valve as shown in FIG. Has been proposed which is closed by a partition wall 54 and opened into a combustion chamber through a small-diameter communication passage 56 provided in the partition wall (see Patent Document 1).

  That is, the burnt gas generated in the combustion stroke of the engine is pushed into the stem of the poppet valve by the combustion pressure, recirculates into the combustion chamber over the subsequent exhaust stroke and intake stroke, and fresh air sucked from the intake valve Mixing is performed to prevent an excessive increase in combustion temperature.

  However, once the burned gas is introduced into the stem, the temperature of the stem rises excessively, making it difficult to use other than an intake valve that is relatively easy to cool. On the other hand, when this is applied to the intake valve, the temperature of the intake air that is inhaled as a reaction rises, resulting in a problem that the intake charging efficiency is lowered.

In order to solve the problem, there is no other way but to stop introducing the burned gas into the stem, but this does not simplify the structure of the exhaust gas recirculation device.
JP 2003-343220 A

  The problem to be solved by the present invention is that the method of controlling the combustion of the air-fuel mixture by temporarily storing the burned gas in the poppet valve draws the burned gas into the stem, so the number of parts constituting the device However, since there is no direct correlation between the size of the combustion chamber and the thickness of the stem, it is difficult to set the amount of burned gas to be returned to the combustion chamber.

  The present invention has a valve body that opens and closes a vent leading to a combustion chamber and a stem connected to the valve body, and a substantially hemispherical recess having a deep central portion is provided on a surface of the valve body facing the combustion chamber. The main feature is that the recess is closed with a partition made of a heat-resistant material, a buffer chamber is provided inside, and the inside and outside of the buffer chamber are communicated by a communication passage provided in the partition.

  According to the burned gas control device of the present invention, it is possible to suppress excessive temperature rise of the combustion gas and suppress generation of nitrogen oxides only by exchanging the valve without greatly modifying the existing engine. At the same time, the charging efficiency in the middle load range can be increased, and the fuel consumption can be reduced.

  In addition, since the buffer chamber is provided in the valve body, the volume of the buffer chamber can be adjusted by appropriately setting the position and size of the partition wall, so the volume of the buffer chamber can be changed according to the size and characteristics of the engine. It is easy to adjust the performance. Furthermore, even if the stem is hollow, the burned gas is not drawn into the stem, so that it is possible to suppress overheating of the stem.

  A first embodiment according to the apparatus of the present invention shown in FIG. 1 will be described below. In the figure, reference numeral 10 denotes a poppet valve used to open and close vents such as an intake port and an exhaust port of a four-stroke engine. The poppet valve 10 has a valve body 12 and a stem 14 connected thereto. Reference numeral 14a denotes a locking groove conventionally used for locking the poppet valve 10 to a spring retainer via a cotter (not shown).

  In this example, the stem 14 forms a so-called hollow stem formed in a hollow shape, and one end thereof is closed by a steel ball 16. The other end of the stem 14 is connected to the valve body 12 having a hollow truncated cone shape in a metallurgical manner.

  The valve body 12 is forged with heat-resistant steel that is slightly thicker than the stem 14, and in the figure, the upper surface thereof is a guide surface 12a that smoothly continues to the outer periphery of the stem 14, and the periphery of the guide surface 12a. And a valve face 12b ground at a cone angle of about 90 °. A cover plate 18 made of a heat-resistant material is welded to the small-diameter opening communicating with the stem 14 of the valve body 12 from the lower side in the drawing to close the opening.

  Thus, a deep, substantially hemispherical recess 20 at the center is formed on the lower surface of the valve body 12, that is, on the side facing the combustion chamber. A partition wall 22 made of a heat-resistant material is further welded to the lower surface of the valve body 12 to close the recess 20.

  Thus, a buffer chamber 24 is formed between the lid plate 18 and the partition wall 22. The partition wall 22 may be a circular flat plate. In this example, the partition wall 22 is formed in a substantially hemispherical shape that bulges toward the combustion chamber, and has increased pressure resistance so that it can withstand high combustion pressure.

  Reference numeral 26 denotes a communication path provided in the partition wall 22, thereby communicating the inside of the buffer chamber 24 with the combustion chamber. In this embodiment, four communication paths 26 are arranged around the axis of the poppet valve 10 at equal intervals on the same circumference.

  Next, a second embodiment of the present invention shown in FIG. 2 will be described. The poppet valve 10 of the second embodiment is an example in the case where the stem 14 is not hollow and is solidly used conventionally.

  That is, in this example, the poppet valve 10 is integrally forged with the valve body 12 and the stem 14, and the central portion of the surface of the valve body 12 on the combustion chamber side is a deep substantially hemispherical recess 20. . As in the case of the first embodiment, the recess 20 is closed by a partition wall 22 provided with a communication passage 26, and a buffer chamber 24 is formed on the inner surface.

  Therefore, in the four-stroke engine assembled with the poppet valve 20 according to the first and second embodiments, a part of the air-fuel mixture sucked into the combustion chamber is pushed into the buffer chamber 24 during the compression stroke in which the piston rises. However, the amount remains below the compression ratio. When ignited at the end of the compression stroke, the air-fuel mixture burns explosively, and high-pressure burned gas generated by the explosion flows into the buffer chamber 24 through the communication passage 26.

  As a result, the combustion chamber pressure increase is prevented by the amount of burnt gas escaped into the buffer chamber 24, so that the increase in combustion pressure and combustion temperature is suppressed, causing knocking and releasing excessive nitric oxide. There is no longer to do.

  In the expansion stroke in which the piston descends, the pressure in the combustion chamber rapidly decreases, and accordingly, the burned gas that has escaped into the buffer chamber 24 returns to the combustion chamber again through the communication path 26. In the meantime, although not a large value, the burned gas recirculated into the combustion chamber acts as a pressure for pushing down the piston.

  The burnt gas remaining in the buffer chamber 24 continues to recirculate into the combustion chamber during the exhaust stroke in which the piston ascends because the diameter of the communication passage 26 is small, and a part thereof is exhausted through an open exhaust valve.

  In the intake stroke in which the piston turns downward, the combustion chamber becomes negative pressure, so the burned gas continues to flow into the combustion chamber, mixes with fresh air flowing in through the intake valve, and is compressed along with fresh air in the subsequent compression stroke. . Thus, the four strokes are completed.

  Therefore, according to the present invention, the burned gas generated in the explosion stroke of the engine can be mixed into the fresh air in the combustion chamber in the subsequent intake stroke without piping outside the combustion chamber. An exhaust gas recirculation device is configured.

  In this apparatus, the amount of burned gas to be mixed into fresh air is experimentally determined according to the amount of nitrogen oxides generated at the maximum output of the engine or the degree of knocking. This is done by adjusting the position and shape of the partition wall 22 and the diameter and number of the communication passage 26.

  In these embodiments, as described above, the amount of burned gas to be recirculated to the combustion chamber is limited by the diameter and length of the stem 14 or whether it is solid or hollow as in the prior art. The optimal amount for the engine can be set easily. Further, since the burned gas is not drawn into the stem, the burned gas in the combustion chamber can be controlled while preventing the stem from being overheated. Needless to say, the buffer chamber 24 may be provided for both intake and exhaust valves, or may be provided for both valves.

It is sectional drawing of the poppet valve which concerns on this invention. It is sectional drawing equivalent to FIG. 1 which shows a modification. It is a bottom view in FIG. It is sectional drawing equivalent to FIG. 1 which shows the conventional hollow poppet valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Poppet valve 12 Valve body 12a Guide surface 12b Valve surface 14 Stem 14a Locking groove 16 Steel ball 18 Cover plate 20 Recess 22 Bulkhead 24 Buffer chamber 26 Communication path

Claims (3)

  A valve body that opens and closes a vent leading to the combustion chamber and a stem that is connected to the valve body. A substantially hemispherical recess having a deep central portion is provided on the surface of the valve body that faces the combustion chamber, and the recess is heat-resistant. A burned gas control device using a poppet valve, which is closed by a partition made of a material and provided with a buffer chamber inside, and the inside and outside of the buffer chamber communicate with each other through a communication passage provided in the partition.   2. The poppet according to claim 1, wherein the stem is formed hollow, the inside thereof is opened to the bottom surface of the recess, the opening is closed by a lid plate, and a buffer chamber is provided between the lid plate and the partition wall. Control device for burnt gas with a valve.   3. The burned gas control device according to claim 1, wherein a plurality of the communication passages are arranged at equal intervals around an axis of the stem. 4.

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