JP2010174843A - Exhaust passage structure of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the flow resistance of combustion gas in a low temperature chamber, and to enhance scavenging efficiency. <P>SOLUTION: The exhaust passage structure of an internal combustion engine includes a main valve performing the exhaustion of combustion gas in a cylinder, a high temperature exhaust passage for discharging high temperature combustion gas to the outside, the low temperature chamber 14 for introducing low temperature combustion gas, a low temperature exhaust passage 15 for discharging combustion gas in the low temperature chamber to the outside, and an auxiliary valve for switching a flow of combustion gas between the high temperature exhaust passage and the low temperature exhaust passage. The low temperature chamber has a cross sectional area with a spiral shape becoming gradually wider in the turning direction of combustion gas from a prescribed position as a starting point SP to an inlet of the low temperature exhaust passage. Furthermore, the auxiliary valve has a straight cylindrical shape and has a skirt formed at a tip thereof. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust passage structure for an internal combustion engine.

  In an internal combustion engine, for example, a two-cycle uniflow type diesel engine, one exhaust valve (hereinafter referred to as a main valve) is incorporated in an exhaust valve box, and the main valve is opened and closed, and combustion is performed in an exhaust receiver (exhaust collecting portion). While exhausting gas (exhaust gas), scavenging is also performed. This scavenging is performed by introducing scavenging from a scavenging port provided on the inner wall of the cylinder liner. Further, the exhaust valve box is provided with a sub valve different from the main valve, and a high temperature chamber and a low temperature chamber separated through the sub valve.

  Then, at the initial opening of the main valve (the initial stage of exhaust), high pressure and high temperature combustion gas is introduced from the cylinder into the high temperature chamber, and through the high temperature exhaust passage for exhausting high temperature combustion gas from the high temperature chamber, It is discharged to the exhaust receiver (outside). In addition, the remaining combustion gas in the cylinder is introduced into the low temperature chamber during the period from the middle opening to the closing of the main valve (mid to late exhaust), and the low temperature for exhausting the low temperature gas from the low temperature chamber. It is discharged outside through the exhaust passage (see, for example, Patent Document 1).

  Therefore, a swirl flow having a strong swirl created at the scavenging port is guided to the low temperature chamber. The high-temperature exhaust gas introduced into the high-temperature chamber is not accompanied by a particularly strong swirl because it is in the early stage of exhaust.

  As an intake device for an internal combustion engine, an independent intake pipe located between the collector and the engine head has an auxiliary valve that closes at the time of lean combustion, idle, or low temperature, a fuel injection valve, and the auxiliary valve bypassing the auxiliary valve and fuel injection An invention has been disclosed in which a straight passage that connects both sides of the injection port of the valve is provided, thereby facilitating the formation of the intake passage (see, for example, Patent Document 2).

Japanese Utility Model Publication No. 02-145617 (FIG. 1) JP 2002-364472 A (page 2-3, FIG. 2)

  The structure of the exhaust passage of the conventional exhaust valve box is, for example, as shown in FIG. 4, in which the low temperature chamber 8 is formed concentrically with the exhaust port 5a of the exhaust valve box 5, and from the middle valve opening to the closing of the main valve. The low-temperature combustion gas introduced into the low temperature chamber 8 through the exhaust port 5a of the exhaust valve box 5 between the cylinder and the center line L connecting the center of the outlet 9a of the low temperature exhaust passage 9 and the center of the low temperature chamber 8 between them. As indicated by the flow lines indicated by arrows A to H, it flows into the low temperature exhaust passage 9 with a strong swirl (swirl flow). In FIG. 4, the length of the streamline indicates the flow velocity of the combustion gas at that position.

  However, as indicated by the flow lines indicated by arrows A to H, the flow velocity of the combustion gas gradually increases from the flow line indicated by the arrow A to the flow line indicated by the arrow H. In the vicinity of the exhaust port 5a of the exhaust valve box 5 indicated by the flow lines of arrows A to G, it is extremely slow.

  That is, since the flow resistance of the combustion gas in the low temperature chamber 8 is large, the flow of the combustion gas discharged from the low temperature chamber 8 to the low temperature exhaust passage 9 is deteriorated, and the flow rate corresponding to the cross-sectional area of the outlet 9a of the exhaust passage 9 The exhaust gas is not exhausted and the scavenging efficiency is extremely poor.

  This is because the low temperature chamber 8 is formed concentrically with the exhaust port 5a of the exhaust valve box 5, so that the center of the outlet 9a of the low temperature exhaust passage 9 and the center of the exhaust port 5a of the cylinder 5 in the low temperature chamber 8 are It is considered that the flow of combustion gas from the low temperature chamber 8 to the low temperature exhaust passage 9 is deteriorated with respect to the center line L connecting the two.

  On the other hand, the intake device disclosed in Patent Document 1 simplifies the configuration of the intake passage, and as in the present invention, the intake valve in the cylinder during the period from the middle valve opening to the closing of the main valve. The invention does not relate to an invention in which the remaining combustion gas is discharged from the low temperature chamber through the low temperature exhaust passage to the exhaust receiver, and the scavenging with strong swirl created at the scavenging port of the cylinder is guided to the low temperature chamber.

  The present invention has been made to solve such a problem, and reduces the flow resistance of the combustion gas in the low-temperature chamber and does not hinder the flow pattern of the scavenging gas with the strong swirl formed at the scavenging port. It is an object of the present invention to provide an exhaust passage structure for an internal combustion engine that can be exhausted to significantly increase scavenging efficiency.

  In order to solve the above-mentioned problems, the means employed by the present invention includes a main valve for exhausting combustion gas in the cylinder, and a high-temperature exhaust valve provided in the exhaust valve box and discharged from the cylinder through the main valve. A high-temperature exhaust passage that discharges combustion gas to the outside, a low-temperature chamber that is provided in the exhaust valve box and introduces low-temperature combustion gas discharged from the cylinder through the main valve, and a low-temperature chamber that is provided in the exhaust valve box In an exhaust passage structure of an internal combustion engine comprising a low temperature exhaust passage for exhausting indoor combustion gas to the outside, and a sub valve provided in an exhaust valve box for switching the flow of combustion gas to the high temperature exhaust passage and the low temperature exhaust passage The low temperature chamber has a spiral shape in which the cross-sectional area from the predetermined position to the inlet of the low temperature exhaust passage gradually increases in the swirling direction of the combustion gas.

  Combustion gas exhausted from the cylinder after the middle of the main valve opening is introduced into the low temperature chamber and is discharged to the outside through the low temperature exhaust passage from the low temperature chamber. The shape of the low greenhouse is a spiral shape in which the cross-sectional area from the predetermined position to the inlet of the low temperature exhaust passage gradually widens in the swirling direction of the combustion gas, creating a strong swirl by scavenging from the scavenging port The accompanying combustion gas can be guided to the low temperature chamber without inhibiting the swirl, and the flow resistance of the combustion gas can be greatly reduced. As a result, the combustion gas having a flow rate corresponding to the cross-sectional area of the low temperature exhaust passage can be discharged smoothly, and the scavenging efficiency is significantly improved.

  In the exhaust passage structure of the internal combustion engine, it is desirable that the inlet of the low temperature chamber and the low temperature exhaust passage are smoothly connected with curved surfaces having different radii of curvature. As described above, the flow resistance of the exhaust gas discharged from the low temperature chamber to the low temperature exhaust passage can be further reduced by smoothly connecting the low temperature chamber and the inlet of the low temperature exhaust passage with curved surfaces having different curvature radii.

  In the exhaust passage structure of the internal combustion engine, the starting point is a position shifted by a predetermined angle in the swirling direction of the combustion gas from a center line connecting the center of the outlet of the low temperature exhaust passage and the center of the exhaust port of the cylinder in the low temperature chamber. Is desirable. In this way, the starting point of the spiral shape of the low temperature chamber is set at a position shifted by a predetermined angle in the swirling direction of the combustion gas from the center line connecting the center of the outlet of the low temperature exhaust passage and the center of the cylinder exhaust port in the low temperature chamber. By doing so, the flow of the combustion gas introduced into the low temperature chamber can be more smoothly guided to the low temperature exhaust passage.

  In the exhaust passage structure of the internal combustion engine, it is preferable that the low temperature chamber is formed by curved surfaces having different radii of curvature that gradually increase from the starting point to the inlet of the low temperature exhaust passage. Thus, by forming the low temperature chamber with curved surfaces having different radii of curvature that gradually increase from the starting point to the inlet of the low temperature exhaust passage, a spiral exhaust passage whose cross-sectional area gradually increases toward the inlet of the low temperature exhaust passage. And an exhaust passage that does not further inhibit the swirl of the combustion gas can be formed.

  In the exhaust passage structure of the internal combustion engine, it is desirable that the low temperature chamber is smoothly enlarged from the starting point to the inlet of the low temperature exhaust passage. Thus, the flow resistance of the introduced combustion gas can be reduced by forming the spiral inner wall surface of the low temperature chamber so as to increase smoothly from the starting point to the inlet of the low temperature exhaust passage. Can be discharged more smoothly into the low temperature exhaust passage.

  In the exhaust passage structure of the internal combustion engine, it is desirable that the sub-valve has a right cylindrical shape and a skirt portion is formed at the tip.

  Alternatively, in order to solve the above-mentioned problems, the other means employed by the present invention include a main valve that exhausts combustion gas in the cylinder and an exhaust valve box that is provided in the exhaust valve box and discharges from the cylinder through the main valve. A high-temperature exhaust passage that discharges the generated high-temperature combustion gas to the outside, a low-temperature exhaust passage that is provided in the exhaust valve box and discharges the low-temperature combustion gas discharged from the cylinder through the main valve to the outside, and an exhaust valve In an exhaust passage structure of an internal combustion engine that is provided in a box and includes a high-temperature exhaust passage and a secondary valve that switches the flow of combustion gas to the low-temperature exhaust passage, the secondary valve has a straight cylindrical shape and a skirt portion at the tip Is that it is formed.

  In this way, by forming a skirt at the tip of the sub-valve that has a right cylindrical shape, the combustion gas discharged from the exhaust port of the cylinder head can be smoothly guided to the low temperature chamber without hindering swirl. Thus, the scavenging efficiency of the combustion gas into the low temperature chamber is significantly improved.

  In the exhaust passage structure of the internal combustion engine, it is desirable that the inner diameter of the sub valve is substantially the same as the exhaust port of the exhaust valve box. Thus, by making the inner diameter of the auxiliary valve substantially the same as the exhaust port of the exhaust valve box, the combustion gas discharged from the exhaust port of the exhaust valve box can be discharged more smoothly into the low temperature chamber. , Scavenging efficiency is further improved.

  In the exhaust passage structure of the internal combustion engine, it is desirable that the skirt portion has a truncated conical cylinder shape in which the outer diameter of the rear end is larger than the outer diameter of the tip. In this way, the outer diameter of the rear end of the skirt portion of the secondary valve is formed in the shape of a truncated conical cylinder having a larger diameter than the outer diameter of the front end, so that it faces the exhaust port of the exhaust valve box and is rearward from the front end. A skirt portion having an outer peripheral surface inclined so as to expand at the end is formed, and the inclined outer peripheral surface of the skirt portion can guide combustion gas discharged from the exhaust port of the exhaust valve box more smoothly to the low temperature chamber. This is possible, and the scavenging efficiency is further improved.

  In the exhaust passage structure of the internal combustion engine, the skirt portion has an outer diameter at the front end smaller than the exhaust port of the cylinder head, and an outer peripheral surface at the rear end is in sliding contact with an inner peripheral surface of the exhaust port of the exhaust valve box. It is desirable to be possible. By making the outer diameter of the tip of the skirt part smaller than the exhaust port of the exhaust valve box and making the outer peripheral surface of the rear end slidably contact the inner peripheral surface of the exhaust port of the cylinder head, It can be smoothly inserted into the exhaust port. Moreover, the clearance gap between an exhaust port and a right cylindrical cylindrical subvalve can be block | closed by making the rear-end outer peripheral surface of a skirt part slide-contact with an exhaust port. As a result, the combustion gas discharged from the exhaust port of the cylinder head can be guided to the low temperature chamber without leakage.

  In the exhaust passage structure of the internal combustion engine, it is desirable that the outer peripheral surface of the skirt portion forms a predetermined angle with respect to the diameter direction of the auxiliary valve. In this way, by forming the outer peripheral surface of the skirt so as to form a predetermined angle with respect to the diameter direction of the sub-valve having a right cylindrical shape, the exhaust valve box faces the exhaust port from the front end to the rear end. The outer peripheral surface inclined so as to expand the diameter can be set to an appropriate angle, and the combustion gas discharged from the exhaust port of the exhaust valve box can be more smoothly guided to the low temperature chamber, and the scavenging efficiency is further improved. .

  As described above, the exhaust passage structure of the internal combustion engine according to the present invention includes the main valve that exhausts the combustion gas in the cylinder, and the high-temperature combustion that is provided in the exhaust valve box and is discharged from the cylinder through the main valve. A high-temperature exhaust passage for discharging gas to the outside, a low-temperature chamber provided in the exhaust valve box for introducing low-temperature combustion gas discharged from the cylinder through the main valve, and a low-temperature chamber provided in the exhaust valve box In the exhaust passage structure of the internal combustion engine, comprising a low-temperature exhaust passage for discharging the combustion gas to the outside, and a sub valve provided in the exhaust valve box for switching the flow of the combustion gas to the high-temperature exhaust passage and the low-temperature exhaust passage, The low greenhouse has a spiral shape in which the cross-sectional area from a predetermined position to the inlet of the low temperature exhaust passage gradually increases in the swirling direction of the combustion gas.

  Alternatively, the exhaust passage structure of the internal combustion engine of the present invention includes a main valve that exhausts the combustion gas in the cylinder, and a high-temperature combustion gas that is provided in the exhaust valve box and discharged from the cylinder through the main valve to the outside. A high-temperature exhaust passage that discharges to the outside, a low-temperature exhaust passage that is provided in the exhaust valve box and discharges low-temperature combustion gas discharged from the cylinder through the main valve to the outside, and a high-temperature exhaust that is provided in the exhaust valve box In an exhaust passage structure of an internal combustion engine that includes a passage and a subvalve that switches the flow of combustion gas to the low temperature exhaust passage, the subvalve has a shape of a straight cylinder and a skirt portion at the tip.

  Therefore, the flow resistance of the combustion gas in the low temperature chamber is reduced, and the scavenging flow with strong swirl created at the scavenging port is exhausted without hindering the flow, so that the scavenging efficiency can be significantly improved. Play.

It is principal part sectional drawing of the exhaust valve box of the diesel engine to which the exhaust passage structure of the internal combustion engine which concerns on one Embodiment of this invention is applied. It is principal part sectional drawing in alignment with the arrow II-II of the exhaust valve box shown in FIG. It is explanatory drawing which showed typically the flow of the combustion gas in the low temperature chamber and low temperature exhaust passage which were shown in FIG. It is explanatory drawing which showed typically the flow of the combustion gas in the low temperature chamber and low temperature exhaust passage in the conventional exhaust passage structure.

  A mode for carrying out the invention of an exhaust passage structure for an internal combustion engine according to the present invention will be described in detail with reference to FIGS.

  FIG. 1 is a sectional view of an essential part of an exhaust valve box to which an exhaust passage structure for an internal combustion engine according to the present invention is applied. As shown in FIG. 1, the exhaust valve box 11 is mounted on the valve seat 2 of the cylinder block 1, and communicates with the main valve 21, the high temperature chamber 12 provided in the exhaust valve box 11, and the high temperature chamber 12. A high temperature exhaust passage 13, a low temperature chamber 14, and a low temperature exhaust passage 15 communicating with the low temperature chamber 14. Further, the high temperature chamber 12 and the high temperature exhaust passage 13 side, and the low temperature chamber 14 and the low temperature exhaust passage 15 side. And a sub valve 25 for switching the flow of the combustion gas.

  Further, a hydraulic cylinder (not shown) that opens the main valve 21, a plurality of, for example, three hydraulic cylinders 31 that are provided in the hydraulic cylinder block 30 and perform the switching operation of the sub valve 25, and the main valve 21 An air piston (not shown) that is fixed to the upper portion of the valve stem 22 to perform the recovery operation of the main valve 21, and an air piston 29 that is fixed to the upper portion of the valve stem 26 of the subvalve 25 to perform the recovery operation of the subvalve 25. The casing includes a casing 35 that houses an air piston of the main valve 21 and an air piston 29 of the sub-valve 25 and forms an air spring chamber 36 for applying air pressure.

  As an example, the exhaust valve box 11 is applied to a two-cycle uniflow diesel engine. In this two-cycle uniflow type diesel engine, there is an intake port (scavenging port) on the side wall of the cylinder liner, and the main valve 21 performs exhaust and scavenging.

  The valve opening operation of the main valve 21 is performed by pushing the valve stem 22 downward in the figure by the hydraulic cylinder that is operated by high pressure oil pressure. The valve closing operation (recovery operation) is performed by the air piston attached to the valve stem 22 pulling up the valve stem 22 upward in the drawing. That is, the air pressure in the air spring chamber 36 formed below the air piston is the operating source for the valve closing operation of the main valve 21.

  The switching operation of the sub valve 25 is performed by operating a plurality of hydraulic cylinders 31 provided in the hydraulic cylinder block 30 by high pressure oil pressure to push the air piston 29 upward in the drawing. Further, the recovery operation is performed by releasing the hydraulic pressure of the hydraulic cylinder 31 and pushing the valve stem 26 downward in the figure by the air piston 29. That is, the air pressure in the air spring chamber 36 formed above the air piston 29 serves as an operating source for the recovery operation of the sub valve 25.

  As shown in FIG. 2, the low temperature chamber 14 has an asymmetric spiral shape with respect to a center line L that connects the center of the outlet 15 a of the low temperature exhaust passage 15 and the center O of the center line of the exhaust port 11 a in the low temperature chamber 14. Is formed. The starting point SP of the spiral is set at a predetermined position in the low greenhouse 14.

  The starting point SP is located slightly on the low temperature chamber 14 side than the connecting portion 15b on one side of the low temperature chamber 14 and the inlet of the low temperature exhaust passage 15, and the center line in the low temperature chamber 14 of the center line of the exhaust port 11a. Centered around O, the low-temperature exhaust passage 15 is provided at a position slightly deviating from the center line L in a spiral direction, that is, at a predetermined angle θ1 from the center line L counterclockwise in the figure.

  In this internal combustion engine, the low-temperature combustion gas introduced into the low-temperature chamber 14 from the cylinder through the exhaust port 11a of the exhaust valve box 11 during the period from the middle valve opening to the closing of the main valve is discharged from the outlet 15a of the low-temperature exhaust passage 15. With respect to the center line L connecting the center and the center of the low temperature chamber 14, it flows into the low temperature chamber 14 with a strong counterclockwise swirl (swirl flow) as viewed from above in FIG. 2.

  That is, the low-temperature chamber 14 has a cross-sectional area from the predetermined position as the starting point SP to the inlet of the low-temperature exhaust passage 15, more specifically, a cross-sectional area from the starting point SP to the low-temperature exhaust passage 15 and the connecting portion 15 c on the other side. In the swirling direction of the combustion gas, a spiral shape gradually widening toward the low temperature exhaust passage 15 is formed. In other words, the low temperature chamber 14 is formed in a right spiral shape whose diameter gradually decreases clockwise as viewed from above in FIG.

  The low greenhouse 14 is formed of curved surfaces having different radii of curvature R2, R3, and R4 from the starting point SP to the connecting portion 15c with the low temperature exhaust passage 15, and these radii of curvature satisfy R4> R3> R2. From the starting point SP to the continuous portion 15c between the low temperature chamber 14 and the inlet of the low temperature exhaust passage 15, the size gradually increases and is connected smoothly.

  The connecting portions 15b and 15c between the low temperature chamber 14 and the inlet of the low temperature exhaust passage 15 are smoothly connected with curved surfaces having curvature radii R1 and R5, respectively. For example, the angle θ1 is about 45 ° to 90 °, and the radii of curvature R2 to R4 forming the spiral shape are about 0.5 to 2.0 times the inner diameter D0 of the outlet 15a of the low temperature exhaust passage 15.

  The sub-valve 25 has a right cylindrical shape, and its outer diameter is slightly smaller than the exhaust port 11a of the exhaust valve box 11, and its inner diameter (sub-valve inner diameter) D1 is substantially the same as the exhaust port 2a of the valve seat 2. The diameter. The exhaust port 11 a of the exhaust valve box 11 has a larger diameter than the exhaust port 2 a of the valve seat 2. The sub-valve 25 has an inner peripheral surface connected to the outer peripheral surface of the valve stem 26 by a plurality of plate-like radii (spokes) 25a. The combustion gas discharged from the cylinder 3 through the main valve 21 is discharged into the high temperature chamber 12 through the radiation 25a.

  The auxiliary valve 25 is formed with a skirt portion 25b whose diameter is reduced from the rear end (upper end in the figure) toward the front end (lower end in the figure) at the front end. The skirt portion 25b has a truncated conical cylindrical shape (conical frustum shape) in which the outer diameter (skirt outer diameter) D2 of the rear end is larger than the inner diameter (skirt inner diameter) D3 of the tip. The angle of the outer peripheral surface with respect to the diametrical direction of the sub-valve 25 having a shape is θ2. The outer diameter D2 of the rear end is larger than the outer diameter of the sub valve 25, and the outer diameter of the front end is smaller than the inner diameter D1 of the sub valve 25.

  The outer peripheral surface of the rear end of the skirt portion 25b is a surface parallel to the outer peripheral surface of the sub-valve 25 having a right cylindrical shape, and the inner peripheral surface of the opening at the tip is the inner periphery of the sub-valve 25 having a right cylindrical shape. The surface is parallel to the surface. Accordingly, the outer peripheral surface of the tip of the skirt portion 25b forms a ridge (knife edge) that forms the angle θ2 with the inner peripheral surface of the opening, and the inner diameter D3 and the outer diameter D4 of the tip are substantially the same.

  The outer diameter D4 of the front end of the skirt portion 25b is slightly smaller than the exhaust port 11a of the exhaust valve box 11, and the outer peripheral surface of the rear end is exhausted from the exhaust valve box 11 as shown by a two-dot chain line. It can be slidably contacted with the inner peripheral surface of the mouth 11a. And the front-end | tip of the subvalve 25 which makes a right cylindrical shape is provided in a row by the substantially center part of the internal peripheral surface of the skirt part 25b.

  For example, when the diameter of the valve face 21a of the main valve 21 is Dv, the ratio D1 / Dv between the inner diameter D1 and Dv of the sub valve 25 is about 0.9 to 1.2, and the outer diameter D2 of the rear end of the skirt portion 25b. The ratio D2 / Dv of the skirt portion 25b is about 1.0 to 1.3, and the ratio D3 / Dv of the inner diameter D3 to the tip Dv of the skirt portion 25b is about 0.7 to 1.0.

  In FIG. 1, the sub valve 25 is switched to the position indicated by the two-dot chain line by the air piston 29 at the initial stage when the main valve 21 starts to open (the initial stage of exhaust), and the skirt portion 25 b has the exhaust valve box 11. The outer peripheral surface of the rear end is in sliding contact with the inner peripheral surface of the exhaust port 11 a and communicates with the cylinder 3 through the exhaust port 2 a of the valve seat 2.

  The auxiliary valve 25 allows the cylinder 3 and the high temperature chamber 12 to communicate with each other through the plate-shaped radiation 25 and closes the low temperature chamber 14 by the cylindrical portion. Thereby, the high-temperature and high-pressure combustion gas in the cylinder 3 is discharged to the high-temperature chamber 12 and is discharged from the high-temperature chamber 12 to the high-temperature exhaust passage 13.

  The auxiliary valve 25 is switched to the low temperature chamber 14 side by the air valve 29 being pushed up to the position indicated by the solid line by the hydraulic cylinder 31 from the middle stage to the latter stage (closed valve) of the main valve 21. Thereby, the high temperature chamber 12 is closed. The low temperature chamber 14 is communicated with the cylinder 3, and the remaining combustion gas in the cylinder 3 is discharged from the exhaust port 11 a of the exhaust valve box 11 to the low temperature chamber 14.

  The combustion gas is smoothly guided into the low temperature chamber 14 along the inclined outer peripheral surface of the skirt portion 25b provided at the tip of the sub valve 25. Thereby, the combustion gas discharged from the cylinder 3 is satisfactorily introduced into the low temperature chamber 14.

  As shown in FIG. 2, the low temperature chamber 14 has a spiral shape in which the cross-sectional area gradually increases in the swirling direction of the combustion gas from the starting point SP to the connecting portion 15 c with the inlet of the low temperature exhaust passage 15, and is smooth. On the other hand, since the connecting portions 15b and 15c connected to the inlet of the low temperature exhaust passage 15 are formed smoothly, the flow resistance of the combustion gas in the low temperature chamber 14 is greatly reduced, and combustion is performed. The gas flows smoothly into the low temperature exhaust passage 15.

  As a result, the combustion gas discharged from the cylinder 3 to the low temperature chamber 14 can be discharged to the low temperature exhaust passage 15 without hindering the strong swirl created at the scavenging port of the cylinder 3. As a result, the combustion gas having a flow rate corresponding to the cross-sectional area of the low temperature exhaust passage 15 can be smoothly discharged, and the scavenging efficiency is significantly improved.

  FIG. 3 shows an example of the flow of combustion gas in the low temperature chamber 14 and the low temperature exhaust passage 15 shown in FIG. The combustion gas introduced into the low temperature chamber 14 from the cylinder 3 shown in FIG. 1 through the exhaust port 11a of the exhaust valve box 11 flows along the spiral inner wall surface 14a as indicated by streamlines A to H indicated by arrows. And is discharged to the low temperature exhaust passage 15.

  The length of the streamlines A to H represents the flow velocity of the combustion gas at that position. As apparent from FIG. 3, the flow velocity of the combustion gas is uniform over the entire circumference of the exhaust port 11a of the exhaust valve box 11 as compared with the exhaust passage structure of the conventional internal combustion engine shown in FIG. As a result, the average flow velocity is increased, and the discharge flow rate of the combustion gas is greatly increased.

  The exhaust passage structure of the internal combustion engine of the present invention is not limited to the exhaust passage of the two-cycle uniflow type diesel engine according to the above-described embodiment, and may be an internal combustion engine having a main valve and a sub valve. Any type of internal combustion engine can be applied to the exhaust passage.

DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Valve seat 2a Exhaust port 3 Cylinder 5 Exhaust valve box 5a Exhaust port 8 Low greenhouse 8a Inner wall surface 9 Low temperature exhaust passage 9a Outlet 11 Exhaust valve box 11a Exhaust port 12 High greenhouse 13 High temperature exhaust passage 14 Low greenhouse 14a Inner wall surface 15 Low-temperature exhaust passage 15a Low-temperature exhaust passage outlets 15b and 15c Connecting portion 21 between low greenhouse and low-temperature exhaust passage 21 Main valve 21a Valve face 22 Valve stem 25 Sub valve 25a Radiation (spoke)
25b Skirt portion 26 Valve stem 29 Air piston 30 Hydraulic cylinder block 31 Hydraulic cylinder 35 Casing 36 Air spring chamber L Center line Dv of low-temperature exhaust passage Valve face diameter D0 Outlet inner diameter D1 of low-temperature exhaust passage D1 Inner diameter D2 of sub-valve Rear outer diameter D3 Inner diameters R1, R5 of the skirt part Curvature radius R2 to R4 of the connecting part of the low temperature greenhouse and the low temperature exhaust passage Curvature radius SP which forms the spiral shape of the low greenhouse The origin O of the spiral shape of the low greenhouse Center θ ₁ Angle of the vortex origin of the cold chamber with respect to the center line of the low temperature exhaust passage θ ₂ Angle with respect to the diameter direction of the outer peripheral surface of the skirt portion of the auxiliary valve

Claims (11)

  A main valve (21) for exhausting the combustion gas in the cylinder (3) and a high-temperature combustion gas provided in the exhaust valve box (11) and exhausted from the cylinder via the main valve are discharged to the outside. A high-temperature exhaust passage (13), a low-temperature chamber (14) provided in the exhaust valve box and introducing a low-temperature combustion gas discharged from the cylinder through the main valve, and the exhaust valve box A low-temperature exhaust passage (15) provided to discharge the combustion gas in the low-temperature chamber to the outside, and a sub-portion provided in the exhaust valve box for switching the flow of the combustion gas to the high-temperature exhaust passage and the low-temperature exhaust passage. In the exhaust passage structure of the internal combustion engine provided with the valve (25), the cold chamber (14) has a cross-sectional area from the predetermined position as a starting point (SP) to the inlet of the cold exhaust passage in the swirling direction of the combustion gas. A spiral shape that gradually widens An exhaust passage structure for an internal combustion engine, characterized in that there.   The internal combustion engine according to claim 1, wherein the cold chamber (14) and the inlet of the cold exhaust passage (15) are smoothly connected with curved surfaces having different radii of curvature (R1, R5). Exhaust passage structure.   The starting point (SP) is a center connecting the center of the outlet (15a) of the low temperature exhaust passage (15) and the center (O) of the exhaust port (2a) of the cylinder (3) in the low temperature chamber (14). The exhaust passage structure for an internal combustion engine according to claim 1 or 2, wherein the exhaust passage structure is located at a position deviated from a line by a predetermined angle (θ1) in the swirling direction of the combustion gas.   The low temperature chamber (14) is formed by curved surfaces having different radii of curvature (R2, R3, R4) that gradually increase from the starting point (SP) to the inlet of the low temperature exhaust passage (15). Item 4. An exhaust passage structure for an internal combustion engine according to any one of Items 1 to 3.   The exhaust passage structure for an internal combustion engine according to any one of claims 1 to 4, wherein the low temperature chamber (14) smoothly increases from the starting point (SP) to an inlet of the low temperature exhaust passage (15). .   The exhaust passage structure for an internal combustion engine according to any one of claims 1 to 5, wherein the auxiliary valve (25) has a shape of a right cylindrical body and a skirt portion (25b) is formed at a tip thereof.   A main valve (21) for exhausting the combustion gas in the cylinder (3) and a high-temperature combustion gas provided in the exhaust valve box (11) and exhausted from the cylinder via the main valve are discharged to the outside. A high-temperature exhaust passage (13), a low-temperature exhaust passage (15) provided in the exhaust valve box and exhausting low-temperature combustion gas discharged from the cylinder through the main valve to the outside, and the exhaust valve In the exhaust passage structure of the internal combustion engine, which is provided in a box and includes an auxiliary valve (25) for switching the flow of the combustion gas to the high temperature exhaust passage and the low temperature exhaust passage, the auxiliary valve (25) An exhaust passage structure for an internal combustion engine characterized by having a cylindrical shape and a skirt (25b) formed at the tip.   The exhaust gas of an internal combustion engine according to claim 6 or 7, wherein an inner diameter (D1) of the auxiliary valve (25) is substantially the same diameter as an exhaust port (11a) of the exhaust valve box (11). Passage structure.   9. The skirt portion (25b) has a truncated conical cylindrical shape having an outer diameter (D2) at the rear end larger than an outer diameter (D4) at the front end. An exhaust passage structure for an internal combustion engine according to any one of the above.   The skirt portion (25b) has an outer diameter (D4) at its front end smaller than the exhaust port (11a) of the exhaust valve box (11) and an outer peripheral surface at the rear end of the exhaust valve box. The exhaust passage structure for an internal combustion engine according to any one of claims 6 to 9, wherein the exhaust passage structure can be slidably contacted with an inner peripheral surface of the internal combustion engine.   The exhaust gas of an internal combustion engine according to any one of claims 6 to 10, wherein the outer peripheral surface of the skirt portion (25b) forms a predetermined angle (θ2) with respect to the diameter direction of the auxiliary valve 25. Passage structure.

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