JP2017150365A - engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool internal EGR gas with a simple structure.SOLUTION: An engine has a partition wall 21 which divides an intake port 11 into a first flow passage and a second flow passage, and carries out internal EGR of making exhaust gas flow back to the intake port 11 and flow into a combustion chamber again. The partition wall 21 provided in the intake port 11 has a body part 21a received in the intake port 11, and protrusion parts 21b which are extended from the body part 21a, pass through the inner wall surface 11a of the intake port 11 and protrude to the outside of the intake port 11. The protrusion parts 21b are provided with heat sinks 21c for radiating the heat transmitted from the body part 21a.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an engine in which exhaust gas flows backward from an exhaust port to an intake port.

  In the engine, when shifting from the exhaust stroke to the intake stroke, valve overlap is performed in which both the intake valve and the exhaust valve are open, so that a part of the exhaust gas flows backward to the intake port, and the exhaust gas is An internal EGR (Exhaust Gas Recirculation) technique for reflowing into the combustion chamber has been put into practical use.

  Exhaust gas (hereinafter referred to as internal EGR gas) flowing into the combustion chamber again by the internal EGR is at a high temperature. Therefore, if the temperature in the combustion chamber rises too much due to the internal EGR gas, it will cause knocking. Therefore, a technique has been proposed in which a part of the refrigerant flow path is disposed in the intake port, and the internal EGR gas flowing back to the intake port is cooled by the refrigerant flow path (for example, Patent Document 1).

JP 2013-253493 A

  In the configuration described in Patent Document 1 described above, a refrigerant flow path must be provided in the intake port, resulting in a complicated configuration.

  Accordingly, an object of the present invention is to provide an engine capable of cooling internal EGR gas with a simple configuration in view of such problems.

  In order to solve the above-mentioned problem, the present invention has a partition that divides the intake port into a first flow path and a second flow path, and performs internal EGR that causes exhaust gas to flow backward to the intake port and re-flow into the combustion chamber. In the engine, the partition wall has a main body portion accommodated in the intake port, and a protruding portion that extends from the main body portion and protrudes outside the intake port through the inner wall surface of the intake port. Is provided with a heat sink that dissipates heat transmitted from the main body.

  At least a part of the heat sink may be provided with an engine cooling water channel.

  According to the present invention, it is possible to cool the internal EGR gas with a simple configuration.

It is a figure explaining the composition of an engine. It is explanatory drawing for demonstrating valve | bulb overlap. It is explanatory drawing for demonstrating a partition.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a diagram illustrating the configuration of the engine 1. As shown in FIG. 1, the engine 1 is provided with a cylinder block 2, a crankcase 3 integrally formed with the cylinder block 2, and a cylinder head 4 fixed to the upper part of the cylinder block 2.

  A cylinder bore 5 is formed in the cylinder block 2, and a piston 6 is slidably supported on the connecting rod 10 in the cylinder bore 5. In the engine 1, a space surrounded by the cylinder head 4, the cylinder bore 5, and the upper surface of the piston 6 is formed as a combustion chamber 7.

  In the engine 1, a crankshaft 9 is rotatably supported in a crank chamber 8 formed in the crankcase 3. The connecting rod 10 is rotatably supported by the crankshaft 9, and the piston 6 is connected to the crankshaft 9 through the connecting rod 10.

  An intake port 11 and an exhaust port 12 are provided in the cylinder head 4 so as to communicate with the combustion chamber 7. A cooling water passage 4 a through which cooling water circulates is formed around the intake port 11 and the exhaust port 12 in the cylinder head 4.

  Further, the tip of the intake valve 13 is located between the intake port 11 and the combustion chamber 7, and the tip of the exhaust valve 14 is located between the exhaust port 12 and the combustion chamber 7. An intake camshaft 15 having a cam 15a and an exhaust camshaft 16 having a cam 16a are provided in a cam chamber surrounded by the cylinder head 4 and a head cover (not shown).

  The intake camshaft 15 has a cam 15a in contact with the other end of the intake valve 13, and rotates the intake valve 13 in the vertical direction by rotating. Thereby, the intake valve 13 opens and closes between the intake port 11 and the combustion chamber 7. The cam 16a is in contact with the other end of the exhaust valve 14, and the exhaust cam shaft 16 moves the exhaust valve 14 in the vertical direction by rotating. Thereby, the exhaust valve 14 opens and closes between the exhaust port 12 and the combustion chamber 7.

  The intake camshaft 15 and the exhaust camshaft 16 are connected to the crankshaft 9 via a timing belt or a timing chain. The intake camshaft 15 is provided with a valve timing varying device 17 that changes the opening / closing timing of the intake valve 13.

  The valve timing varying device 17 changes the opening / closing timing of the exhaust valve 14 by adjusting the relative phase of the exhaust camshaft 16 with respect to the crankshaft 9 by hydraulic pressure. The variable valve timing device 17 can continuously change the opening / closing timing of the exhaust valve 14 between the most advanced timing and the most retarded timing.

  The variable valve timing device 17 may change the opening / closing timing of the intake valve 13 by adjusting the relative phase of the intake camshaft 15 with respect to the crankshaft 9 by hydraulic pressure. Furthermore, a valve timing varying device 17 may be provided on each of the intake camshaft 15 and the exhaust camshaft 16 so as to change the opening / closing timing of both the intake valve 13 and the exhaust valve 14.

  The cylinder head 4 is provided with a spark plug 18 so that the tip is located in the combustion chamber 7. Then, the air-fuel mixture flowing into the combustion chamber 7 through the intake port 11 is ignited and burned by the spark plug 18 at a predetermined timing. By such combustion, the piston 6 reciprocates, and the reciprocating motion is converted into the rotational motion of the crankshaft 9 through the connecting rod 10.

  An intake pipe 19 is attached to the opening of the intake port 11 in the outer wall surface of the cylinder head 4. An intake passage 20 through which intake air is guided is formed inside the intake pipe 19, and the intake passage 20 and the intake port 11 communicate with each other.

  A partition wall 21 is disposed inside the intake port 11. The partition wall 21 has a plate-like main body portion 21 a, and the main body portion 21 a extends from the inside of the intake port 11 to the inside of the intake flow path 20. The main body portion 21a divides the downstream side of the intake flow path 20 and the upstream side of the intake port 11 into the vertical direction in FIG. 1 along the flow direction of the intake air, and the first flow path 22 and the second flow path 23. Form. That is, a part of each of the intake flow path 20 and the intake port 11 is partitioned into the first flow path 22 and the second flow path 23 by the partition wall 21.

  Further, the partition wall 21 is arranged to be deviated downward in FIG. 1 with respect to the center of the intake flow path 20 and the intake port 11, and the upper first flow path 22 partitioned by the partition wall 21 is disposed on the lower side. The flow path is wider than the second flow path 23. A TGV (Tumble Generation Valve) 24 is disposed upstream of the partition wall 21 in the intake flow path 20 and opens and closes the first flow path 22.

  As shown in FIG. 1, when the opening of the TGV 24 is minimized and the first flow path 22 is almost closed by the valve body 24a of the TGV 24, the intake air guided to the intake flow path 20 passes through the second flow path 23. Then head to the combustion chamber 7.

  When the engine load is small and the intake flow rate is small, the opening degree of the first flow path 22 is reduced, and most of the intake air is passed to the second flow path 23 side. In this way, by letting the intake air with increased flow velocity flow into the combustion chamber 7, a vertical vortex flow (tumble flow) is formed in the combustion chamber 7 to realize rapid combustion of the fuel, thereby improving fuel efficiency and combustion stability. And

  The ECU 25 is constituted by a microcomputer including a central processing unit (CPU), a ROM storing programs and the like, a RAM as a work area, and the like. The ECU 25 controls the valve timing varying device 17 while controlling the opening degree of the TGV 24 by an actuator (not shown).

  Specifically, the ECU 25 controls the opening / closing timing of the intake port 11 and the exhaust port 12 so that the valve timing variable device 17 has a valve overlap in which both the intake port 11 and the exhaust port 12 are opened. Let

  FIG. 2 is an explanatory diagram for explaining valve overlap. Here, taking an example of a 4-stroke engine, the opening / closing operation of the intake valve 13 and the exhaust valve 14 that make a round until the crankshaft 9 makes two revolutions will be described. FIG. 2 (a) shows the opening / closing timing of the intake valve 13, and FIG. 2 (b) shows the opening / closing timing of the exhaust valve 14. In FIG. 2, an alternate long and short dash line arrow indicates a period during which the intake valve 13 is open, and a broken line arrow indicates a period during which the exhaust valve 14 is open.

  As shown in FIG. 2A, the intake valve 13 opens before the top dead center of the piston 6 (indicated by TDC in FIG. 2) (indicated by IO in FIG. 2A). At this time, the exhaust valve 14 is already open, and the valve overlap period starts as shown by the solid arrow a in FIG.

  Then, after exceeding the top dead center of the piston 6, the exhaust valve 14 is closed (indicated by EC in FIG. 2B), and the valve overlap period ends. Thereafter, as shown in FIG. 2A, the bottom dead center of the piston 6 (indicated by BDC in FIG. 2) is exceeded, the intake valve 13 is closed (indicated by IC in FIG. 2A), and the compression stroke Starts.

  Then, after the fuel is ignited by the spark plug 18 near the top dead center and enters the combustion stroke, the exhaust valve 14 opens before the piston 6 reaches the bottom dead center (indicated by EO in FIG. 2B). ), The intake valve 13 is opened again before the top dead center after the bottom dead center, and the valve overlap period starts again.

  The variable valve timing device 17 can adjust the valve overlap period by increasing the opening timing of the intake valve 13 or delaying the closing timing of the exhaust valve 14.

  The ECU 25 controls the valve timing varying device 17 to generate valve overlap, thereby performing internal EGR that causes exhaust gas to flow backward from the combustion chamber 7 to the intake port 11 and to flow into the combustion chamber 7 again.

  FIG. 3 is an explanatory diagram for explaining the partition wall 21. FIG. 3A shows a cross section taken along line III (a) -III (a) of FIG. 1, and FIG. The cross section of the site | part corresponding to Fig.3 (a) in an example is shown. In FIG. 3, the cooling water in the cooling water channel 4a is indicated by hatching.

  As shown in FIG. 3 (a), the partition walls 21 are respectively located on both end sides in the left-right direction (the width direction of the main body portion 21a) in FIG. 3 (a) with respect to the main body portion 21a accommodated in the intake port 11. A protruding portion 21b is provided.

  The protruding portion 21 b extends from the main body portion 21 a (is formed continuously with the main body portion 21 a), passes through the inner wall surface 11 a of the intake port 11, and protrudes outside the intake port 11. Here, a cooling water channel 4a is formed outside the intake port 11 with a wall 4b (a part of the cylinder head 4) interposed therebetween. The protruding portion 21b passes through the wall portion 4b (through the through hole 4c formed in the wall portion 4b) and protrudes to the cooling water channel 4a.

  As shown in FIG. 1, the main body portion 21a has a plate shape and extends in the flow direction of intake air, and the protruding portion 21b and the through hole 4c are in the flow direction of intake air (see FIG. 3 (a), extending in a direction perpendicular to the drawing.

  The partition wall 21 is cast into the cylinder head 4, and the sealing performance between the through hole 4 c of the wall portion 4 b and the protruding portion 21 b is high, and leakage of cooling water to the intake port 11 is suppressed. .

  Each of the two protruding portions 21b is provided with a heat sink 21c. The heat sink 21c includes a plurality of fins 21e standing up from the base 21d. The fins 21e extend in the direction of intake air flow (in FIG. 3A, the direction perpendicular to the drawing) in the same manner as the main body 21a.

  The fins 21e are arranged at equal intervals in the left-right direction in FIG. 3A, and in FIG. 3A, the fins 21e are arranged in the up-down direction rather than the thickness in the left-right direction. It extends for a long time. As described above, the fin 21e has a shape in which the surface area increases with respect to the volume, and the heat dissipation from the surface of the fin 21e is excellent.

  The heat sink 21c is immersed in the cooling water of the cooling water passage 4a, and dissipates heat transferred from the main body 21a to the cooling water.

  As described above, when performing the internal EGR, the variable valve timing device 17 provides the valve overlap period or extends the valve overlap period in accordance with the control of the ECU 25. Then, the exhaust gas flows back into the intake port 11.

  Since the main body 21a of the partition wall 21 in the intake port 11 is cooled by the heat sink 21c, the exhaust gas that has flowed back contacts the main body 21a and is cooled. Therefore, an excessive temperature rise in the combustion chamber 7 is suppressed, and the occurrence of knocking can be suppressed. Moreover, since the temperature of internal EGR gas falls, it becomes possible to increase the quantity of internal EGR gas.

  Further, when the temperature of the intake air is low and the temperature of the cooling water is warm, such as when the engine 1 is started, the temperature of the intake air can be raised by the partition wall 21 and the temperature of the combustion chamber 7 can be raised quickly. Become.

  In the modification, as shown in FIG. 3B, the partition wall 31 is formed by processing a single flat plate with a main body 31a, a protrusion 31b, and a fin 31e of the heat sink 31c.

  Specifically, the heat sink 31c is not provided with a base portion, and the fin 31e is formed in, for example, a star shape by bending a flat plate continuous from the protruding portion 31b. Therefore, the surface area of the heat sink 31c can be increased with a simpler configuration. In the example of FIG. 3B, the partition wall 31 is formed by processing a single flat plate. However, for example, a material in which a plurality of steel plates are joined by welding, such as a tailored blank material, is used. May be formed. In this case, for example, the thickness of the heat sink 31c (fin 31e) may be reduced with respect to the thickness of the main body 31a.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the above-described embodiment and modification, the case where at least a part of the heat sinks 21c and 31c is arranged in the cooling water passage 4a provided in the cylinder head 4 has been described. However, the heat sinks 21c and 31c are provided with the cooling water passage 4a. It does not have to be distributed to. However, the cooling effect of the internal EGR gas can be significantly increased by arranging the heat sinks 21c and 31c in the cooling water channel 4a.

  Moreover, the shape of the fins 21e and 31e shown in the embodiment and the modification described above is an example, and any shape may be used as long as the heat from the main body portions 21a and 31a can be radiated.

  The present invention can be used for an engine in which exhaust gas flows backward from an exhaust port to an intake port.

DESCRIPTION OF SYMBOLS 1 Engine 4a Cooling water channel 11 Intake port 11a Inner wall surface 21, 31 Partition wall 21a, 31a Main part 21b, 31b Projection part 21c, 31c Heat sink 22 First flow path 23 Second flow path

Claims (2)

An engine that has a partition wall that divides an intake port into a first flow path and a second flow path, and performs internal EGR that causes exhaust gas to flow backward to the intake port and flow into the combustion chamber again.
The partition is
A main body housed in the intake port;
A projecting portion that extends from the main body and penetrates the inner wall surface of the intake port and projects outside the intake port;
Have
The engine, wherein the protrusion is provided with a heat sink that dissipates heat transmitted from the main body.   The engine according to claim 1, wherein at least a part of the heat sink is provided with a cooling water channel of the engine.

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