JP2017150379A - engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fuel consumption and combustion stability.SOLUTION: In an engine in which an intake port 11 is divided into a first flow channel 22 and a second flow channel 23 by a partitioning wall 21, and an opening of the first flow channel 22 separating from a combustion chamber with respect to the second flow channel 23 is variable by a valve, the partitioning wall 21 includes a straight portion 21b extended from an upstream side toward a downstream side of the intake port 11 straight, and a bent portion 21c bent to a first flow channel 22 side with respect to the straight portion 21b at a downstream side of the straight portion 21b, thus tumble flow can be enhanced in low load of the engine in comparison with a case of the partitioning wall not provided with the bent portion 21c.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an engine provided with a partition wall that partitions an intake port.

  Conventionally, in order to generate a tumble (vertical vortex) flow in a combustion chamber, an engine having a partition wall that partitions an intake port into two flow paths (a first flow path and a second flow path) has been developed (for example, Patent Document 1).

  In this engine, when the load is low and the intake flow rate is low, the flow rate of the intake air flowing into the combustion chamber from the second flow path is reduced by restricting the opening degree of the first flow path partitioned by the partition wall by TGV (Tumble Generation Valve). And a strong tumble flow can be generated in the combustion chamber.

Japanese Patent No. 3694963

  However, when the engine speed and load are low and the intake flow rate is low, the momentum of the intake air introduced from the intake port to the combustion chamber is small, and the intake air collides with the intake valve, so that a desired tumble flow is not formed. There is a fear.

  In such a case, the tumble flow formed in the combustion chamber becomes weak, the combustion speed of the air-fuel mixture containing fuel decreases, the fuel consumption deteriorates due to the decrease in the dilution and lean limit, or the combustion stability There was a problem that would get worse.

  Therefore, in view of such a problem, an object of the present invention is to provide an engine capable of improving fuel consumption and combustion stability.

  In order to solve the above-described problem, the present invention provides an intake port having a first flow path and a second flow path divided by a partition wall, the opening of the first flow path being separated from the combustion chamber rather than the second flow path. In which the partition is linearly extended from the upstream side to the downstream side of the intake port, and the straight portion is located on the downstream side of the straight portion. With respect to the first flow path side.

  The intake port may include a plurality of openings facing the combustion chamber, and the bent portion may be curved in accordance with the shape of the opening.

  The intake port may be provided with a plurality of openings facing the combustion chamber, and the bent portion may be formed at both ends in the direction in which the openings are arranged at the downstream end of the straight portion.

  According to the present invention, fuel consumption and combustion stability can be improved.

It is a figure explaining the composition of an engine. It is a figure for demonstrating the shape of a partition. It is a figure explaining the mode of the intake air which flows through the 2nd channel. It is a figure explaining the difference in the flow of the intake air by a partition and the partition which does not have a bending part. It is a figure which shows the graph which measured the average flow velocity and turbulence intensity in a combustion chamber by the partition and the partition which does not have a bending part in case an intake air flow rate is comparatively slow. It is a figure explaining the partition of a 2nd embodiment. It is a figure explaining the partition of a 3rd embodiment.

  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.

<First Embodiment>
FIG. 1 is a diagram illustrating the configuration of the engine 1. In the following, the axial direction of the cylinder bore 5 and the piston 6 is the vertical direction, the direction in which the piston 6 is directed from the bottom dead center to the top dead center is upward, and the direction in which the piston 6 is directed from the top dead center to the bottom dead center is downward. This will be described as a direction.

  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. Thereby, the piston 6 is connected to the crankshaft 9 via 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. The intake port 11 is divided into two flow paths on the way from the upstream to the downstream, and two openings facing the combustion chamber 7 are formed. Further, the exhaust port 12 has two openings facing the combustion chamber 7, and the flow path is integrated into one on the way from the upstream to the downstream.

  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 to which a cam 15a is fixed and an exhaust camshaft 16 to which a cam 16a is fixed are provided in a cam chamber surrounded by a cylinder head 4 and a head cover (not shown). The intake camshaft 15 and the exhaust camshaft 16 are connected to the crankshaft 9 via a timing belt, and rotate as the crankshaft 9 rotates.

  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 cylinder head 4 is provided with a spark plug (not shown) 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 at the spark plug 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.

  In the engine 1, an intake pipe 19 is attached to an opening portion 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 extends from the inside of the intake port 11 to the inside of the intake flow path 20. The partition wall 21 divides the downstream side of the intake passage 20 (combustion chamber 7 side) and the upstream side of the intake port 11 in the vertical direction in FIG. A second flow path 23 is formed. 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.

  A TGV (Tumble Generation Valve) 24 is disposed on the upstream side of the partition wall 21 in the intake flow path 20, and has an opening degree of the first flow path 22 that is further away from the combustion chamber 7 than the second flow path 23. Variable.

  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 TGV 24, the intake air guided to the intake flow path 20 passes through the second flow path 23 and is in the combustion chamber. Head to 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, in the engine 1, the intake air with an increased flow velocity is caused to flow into the combustion chamber 7, thereby generating a tumble flow indicated by the arrow in the figure in the combustion chamber 7, realizing rapid fuel combustion, and dilution / lean combustion Improve limits and combustion stability. This makes it possible to improve fuel efficiency.

  FIG. 2 is a view for explaining the shape of the partition wall 21. As shown in FIG. 2, the intake port 11 has an inlet portion 11 a communicated with the intake flow path 20 curved toward the combustion chamber 7 side, and an outlet portion 11 b communicated with the combustion chamber 7. Curved toward 7 side. In the intake port 11, a straight portion 11c between the inlet portion 11a and the outlet portion 11b extends linearly.

  The partition wall 21 extends linearly along the curved portion 21a curved along the shape of the inlet portion 11a of the intake port 11 and along the straight portion 11c of the intake port 11 (from the upstream side to the downstream side of the intake port 11). The existing straight portion 21b and a bent portion 21c which is located on the downstream side of the straight portion 21b and is bent toward the first flow path 22 are integrally formed.

  The bent portion 21c extends along a straight line L1 connecting the downstream end of the straight portion 21b and the upper end 11e of the opening 11d facing the combustion chamber 7 in the intake port 11, and the length is 5 mm to 10 mm. ing. The bent portion 21c may extend within ± 10 ° with reference to an angle θ formed by the straight line L2 from which the straight portion 21b extends and the straight line L1.

  As described above, in the engine 1, when the engine load is low and the intake flow rate is small, the first flow path 22 is closed by the TGV 24 and the intake air is allowed to pass through only the second flow path 23. At this time, the partition wall 21 increases the flow velocity of intake air (intake air flow velocity) by the curved portion 21a and the straight portion 21b, and adjusts the direction of intake air, that is, the flow direction by the bent portion 21c.

  FIG. 3 is a diagram for explaining the state of intake air flowing through the second flow path 23. In FIG. 3, the direction of intake air flow is indicated by an arrow line. As shown in FIG. 3, among the intake air that passes through the second flow path 23, when the intake air that passes in the vicinity of the straight portion 21 b of the partition wall 21 reaches the bent portion 21 c, the bent portion is caused by the Coanda effect due to the viscosity of the air. The flow direction is changed to the 21c side.

  When the flow velocity of the intake air is high, a separation region (shown by hatching in FIG. 3) is formed downstream of the separation point 30 that is the boundary between the straight portion 21b and the bent portion 21c. In the separation region, the intake air forms a separation vortex attracted to the bent portion 21c side.

  When the engine speed and load are low and the intake air flow rate is relatively slow, the air does not separate or the intake air reattaches to the bent portion 21c and flows along the bent portion 21c on the downstream side of the separation region. As a result, the intake air is guided from the upper end side of the intake valve 13 to the combustion chamber 7. Therefore, when the intake air flow rate is relatively slow, the upper end of the intake valve 13 is attracted to the first flow path 22 side (the upper end side of the intake valve 13) due to the influence of the bent portion 21c. From the side, intake air is more efficiently guided into the combustion chamber 7.

  On the other hand, when the engine speed and load are high and the intake flow velocity is relatively fast, the intake air separated from the partition wall 21 at the separation point 30 does not reattach to the bent portion 21c and remains at the upper end of the intake valve 13 as it is. It will be led to the combustion chamber 7 from the side.

  FIG. 4 is a diagram for explaining a difference in intake air flow between the partition wall 21 and the partition wall W that does not have a bent portion. FIG. 4A shows the flow of intake air by the partition wall 21 when the intake flow velocity is relatively fast, and FIG. 4B shows the flow of intake air by the partition wall W when the intake flow velocity is relatively fast, FIG. 4C shows the flow of intake air through the partition wall 21 when the intake flow velocity is relatively slow, and FIG. 4D shows the flow of intake air through the partition wall W when the intake flow velocity is relatively slow.

  As shown in FIGS. 4A and 4B, when the engine load is high and the intake air flow rate is relatively high, even the partition wall 21 having the bent portion 21c has the bent portion. Even if there is no partition wall W, the intake air that has collided with the intake valve 13 flows along the back surface of the intake valve 13, and is thus introduced into the combustion chamber 7 from the upper end side of the intake valve 13.

  On the other hand, when the engine load is low and the intake air flow velocity is relatively slow, as shown in FIG. 4C, the partition wall 21 having the bent portion 21c takes in the intake air on the downstream side of the separation region as described above. Is reattached to the bent portion 21 c and flows along the bent portion 21 c, thereby being guided from the upper end side of the intake valve 13 to the combustion chamber 7. As a result, even when the intake air flow rate is slow, the tumble flow formed in the combustion chamber 7 becomes strong, and the combustion speed of the air-fuel mixture containing fuel can be increased, and the fuel efficiency and combustion stability can be improved as a whole. .

  However, as shown in FIG. 4D, in the partition wall W that does not have a bent portion, the intake air flowing along the partition wall W directly collides with the intake valve 13. At this time, since the intake air flow rate is slow, a part of the intake air colliding with the intake valve 13 is guided into the combustion chamber 7 from the lower end side of the intake valve 13. When the amount of intake air introduced into the combustion chamber 7 from the lower end side of the intake valve 13 increases, the tumble flow formed in the combustion chamber 7 becomes weak, the combustion speed of the air-fuel mixture containing fuel decreases, and overall fuel consumption and combustion stability The sex will get worse.

  FIG. 5 is a diagram showing a graph in which the average flow velocity and turbulence intensity in the combustion chamber 7 are measured by the partition wall 21 and the partition wall W having no bent portion when the intake air flow rate is relatively slow. is there. FIG. 5 (a) is a graph in which the horizontal axis represents the crank angle and the vertical axis represents the average flow velocity, and FIG. 5 (b) represents the crank angle on the horizontal axis and the turbulence intensity on the vertical axis. It is a graph. In FIG. 5, when the crank angle is 360 °, the piston 6 is located at the top dead center, and when the crank angle is in the range of 340 ° to 360 °, the spark plug is ignited.

  As shown in FIG. 5A, when the partition wall 21 having the bent portion 21c is used, the partition wall W having no bent portion is used in the crank angle range of 300 ° to 450 °. In comparison, it can be seen that the average flow velocity in the combustion chamber 7 is higher. That is, when the partition wall 21 having the bent portion 21c is used, a stronger tumble flow is formed as compared with the case where the partition wall W having no bent portion is used.

  Further, as shown in FIG. 5B, when the partition wall 21 having the bent portion 21c is used, the partition wall W having no bent portion is used in a crank angle range of 315 ° to 365 °. It can be seen that the turbulence intensity in the combustion chamber 7 is greater than in the case.

  As described above, in the engine 1 using the partition wall 21 having the bent portion 21c, the average flow velocity is high and the turbulence strength is large at least at the timing when the spark plug is ignited. However, it became clear that the combustion rate of the air-fuel mixture containing fuel can be increased as compared with the engine using the partition wall W having no bent portion.

  As described above, in the engine 1, the partition wall 21 having the bent portion 21c can form a strong tumble flow even when the intake air flow rate is relatively slow, and increases the combustion speed of the air-fuel mixture including fuel. Overall, fuel economy and combustion stability can be improved.

<Second Embodiment>
FIG. 6 is a diagram illustrating the partition wall 100 according to the second embodiment. FIG. 6A is a view showing the partition wall 100 disposed in the cylinder head 4, and FIG. 6B is a view showing the partition wall 100 viewed from the combustion chamber 7 side. In the second embodiment, a partition wall 100 is provided in place of the partition wall 21 of the first embodiment, and the other configuration is the same as that of the first embodiment, so that the same reference numerals are given. The description is omitted.

  As shown to Fig.6 (a), the partition part 100 of 2nd Embodiment is integrally formed with the curved part 21a, the straight part 21b, and the bending part 100c. Similarly to the bent portion 21c of the first embodiment, the bent portion 100c extends along a straight line L1 that connects the downstream end of the straight portion 21b and the upper end of the opening 11d facing the combustion chamber 7 of the intake port 11 and 11e. The length is 5 mm to 10 mm.

  Further, as shown in FIG. 6B, the bent portion 100c is formed in a convex shape with the central portion bulging upward along the shape of the upper end side of the opening 11d facing the combustion chamber 7 in the intake port 11. Two convex portions 100d are formed. Therefore, the bent portion 100c extends as a whole toward the upper end of the opening 11d facing the combustion chamber 7 of the intake port 11, and is curved in accordance with the shape of the upper end side of the two openings 11d.

  In the partition wall 100, the intake air can be passed toward the combustion chamber 7 in accordance with the shape of the gap between the intake valve 13 and the opening 11d. Therefore, when the engine load is low and the intake air flow rate is relatively slow, the partition wall 21 As compared with the above, more intake air can be introduced into the combustion chamber 7 from the upper end side of the intake valve 13.

<Third Embodiment>
FIG. 7 is a diagram illustrating the partition wall 200 according to the third embodiment. FIG. 7A is a view showing the partition wall 200 viewed from the combustion chamber 7 side, and FIG. 7B is a view showing the flow of intake air guided to the combustion chamber 7 when the partition wall 200 is used. FIG. 7C is a diagram showing the flow of intake air introduced into the combustion chamber 7 when the partition wall W having no bent portion is used. In the third embodiment, a partition wall 200 is provided instead of the partition wall 21 of the first embodiment, and the other configuration is the same as that of the first embodiment, and therefore, the same reference numerals are given. The description is omitted.

  As shown in FIG. 7A, the partition wall 200 of the third embodiment is integrally formed with a curved portion 21a, a straight portion 21b, and a bent portion 200c. In the bent portion 200c, both ends in the direction in which the openings 11d orthogonal to the flow direction of the intake are arranged extend along a straight line L1 (see FIG. 2) at the downstream end of the straight portion 21b.

  In the engine 1 using the partition wall 200, as shown in FIG. 7B, the cross-sectional area of the central portion of the second flow path 23 at the downstream end of the partition wall 200 is the both ends where the bent portions 200c are provided. Since it is smaller than the cross-sectional area on the side, the intake air flow velocity at the central portion is higher than the intake air flow velocity on both ends.

  As a result, the intake air guided from the intake port 11 to the combustion chamber 7 has the same size in the direction in which the openings 11d are arranged. As a result, the tumble flow formed in the combustion chamber 7 can be strengthened (improved tumble flow quality), the fuel combustion speed can be increased, and fuel efficiency and combustion stability can be improved as a whole.

  On the other hand, in the engine using the partition wall W, as shown in FIG. 7C, the intake air flow velocity at the central portion is lower than the intake air flow velocity at both ends at the downstream end portion of the partition wall W. In such a case, the intake air guided from the intake port 11 to the combustion chamber 7 is faster at both ends than the center in the direction in which the openings 11d are arranged. Thereby, the quality of the tumble formed in the combustion chamber 7 is deteriorated, and the tumble persistence at the compression top dead center is deteriorated. As a result, the combustion speed of the air-fuel mixture containing fuel is reduced, and the fuel consumption and combustion stability are generally deteriorated.

  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, the bent portions 21c, 100c, and 200c extend along the straight line L1, but bend at least toward the first flow path 22 with respect to the straight line L1 that the straight portion 21b extends. If you do.

  The present invention can be used for an engine provided with a partition wall for partitioning an intake port.

DESCRIPTION OF SYMBOLS 1 Engine 4 Cylinder head 7 Combustion chamber 11 Intake port 13 Intake valve 21, 100, 200 Partition 21b Straight part 21c, 100c, 200c Bending part 22 1st flow path 23 2nd flow path

Claims (3)

An engine in which an intake port is divided into a first flow path and a second flow path by a partition, and an opening degree of the first flow path that is separated from the combustion chamber rather than the second flow path is variable by a valve,
The partition is
A straight portion extending linearly from the upstream side to the downstream side of the intake port;
A bent portion located downstream of the straight portion and bent toward the first flow path with respect to the straight portion;
An engine comprising: The intake port is provided with a plurality of openings facing the combustion chamber,
The bent portion is
The engine according to claim 1, wherein the engine is curved in accordance with the shape of the opening. The intake port is provided with a plurality of openings facing the combustion chamber,
The bent portion is
2. The engine according to claim 1, wherein the opening is formed at both ends in the direction in which the openings are arranged at the downstream end of the straight portion.

Images