JP7296272B2 - internal combustion engine - Google Patents

Description

The present invention relates to an internal combustion engine in which an intake collector incorporates an intercooler.

For example, Patent Document 1 discloses a surge tank positioned downstream of a turbocharger, a plurality of connection pipes for supplying intake air from the surge tank to each cylinder, an intercooler disposed in the surge tank, and a surge tank. An internal combustion engine is disclosed that includes a bypass passage that communicates with the upstream side of a supercharger in a portion on the downstream side of an intercooler inside.

The pressure distribution of the intake air flow in the surge tank on the downstream side of the intercooler becomes substantially uniform along the direction of the cylinder rows as the supercharged intake air passes through the fin row of the intercooler's electrothermal fins and is rectified. ing.

In Patent Document 1, the bypass passage is connected to a tubular member inserted into the surge tank. The tubular member is arranged substantially parallel to the arrangement of the connection ports of the plurality of connection pipes with the surge tank.

The tube wall of this tubular member is formed with four hole rows each made up of through holes arranged parallel to the axis. The through-holes in the row of holes are arranged so as to decrease toward the downstream side in the flow direction in the bypass passage so that the pressure distribution in the direction along the tubular member of the intake flow after passing through the tubular member becomes substantially uniform. formed.

JP-A-4-237826

However, in Patent Document 1, if the pressure distribution of the intake air in the surge tank on the upstream side of the intercooler is uneven along the cylinder row direction, the intake air is rectified by passing through the fin row of the intercooler. Even so, the pressure distribution of the intake air in the surge tank on the downstream side of the intercooler may become non-uniform along the direction of the row of cylinders.

In other words, in Patent Document 1, sufficient consideration is not given to the pressure distribution of the intake air in the surge tank on the upstream side of the intercooler.

Therefore, in Patent Document 1, if the pressure distribution of the intake air along the cylinder row direction in the surge tank on the upstream side of the intercooler is uneven, the intake air after passing through the tubular member increases in the cylinder row direction. The pressure distribution becomes non-uniform, the flow velocity distribution in the plurality of connecting pipes becomes uneven, and there is a risk that the in-cylinder flow of the intake gas deteriorates.

An internal combustion engine of the present invention has a turbocharger, an intake collector that distributes intake air to intake ports of each cylinder, and an intercooler that is arranged inside the intake collector, and the pressure inside the intercooler is A loss is set to have a predetermined gradient, and the intake collector is configured to allow the intake air to flow into the inlet of the intake port only from the outlet of the intercooler that faces the inlet. Having a plurality of partition walls partitioning the downstream side of the outlet of the cooler, the partition walls being formed with through holes, and the through holes being provided with control valves capable of opening and closing the through holes. is characterized by

In the internal combustion engine of the present invention, even if there is a bias in the flow velocity distribution and pressure distribution of the intake air in the intake collector on the upstream side of the intercooler, the bias in the flow velocity distribution and pressure distribution of the intake air in the intake collector on the downstream side of the intercooler is reduced. It becomes possible to Therefore, in the internal combustion engine of the present invention, it is possible to reduce the difference in the flow rate of the intake air flowing into the cylinder through the plurality of intake valves, thereby achieving the desired gas flow in the cylinder (for example, suppressing the swirl component as much as possible). It is possible to generate a tumble flow).

1 is an explanatory view schematically showing an internal combustion engine according to a first embodiment of the invention; FIG. FIG. 2 is an explanatory diagram schematically showing an internal combustion engine of a comparative example; FIG. 2 is an explanatory diagram schematically showing an internal combustion engine according to a second embodiment of the invention; FIG. 5 is an explanatory view schematically showing an intake collector and an intercooler in an internal combustion engine according to a third embodiment of the invention;

An embodiment of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram schematically showing an internal combustion engine 1 of a first embodiment of the invention.

An EGR passage 4 is connected to the intake passage 2 of the internal combustion engine 1 at a position downstream of the throttle valve 3 in the intake air flow direction. The EGR passage 4 enables exhaust gas recirculation (EGR) in which part of the exhaust gas is recirculated to the intake passage 2 from an exhaust passage (not shown).

again. A supercharger 5 for compressing intake air is arranged in the intake passage 2 at a position downstream of the connection position of the EGR passage 4 in the intake air flow direction.

The supercharger 5 is, for example, a turbocharger that coaxially includes a compressor provided in an intake passage and an exhaust turbine provided in an exhaust passage. As the supercharger 5, a mechanical supercharger (supercharger) in which a compressor provided in an intake passage is driven by an internal combustion engine, or an electric supercharger in which a compressor provided in an intake passage is driven by an electric motor. machine.

An intake collector 6 having a certain volume is provided in the intake passage 2 on the downstream side of the supercharger 5 . The intake collector 6 is arranged along the row of cylinders.

The intake collector 6 distributes the intake air to the intake port 7 of each cylinder. A downstream side wall portion 6 a of the intake collector 6 is connected to an upstream end portion 8 that is an inlet portion of an intake port 7 . The downstream side wall portion 6a is a wall portion along the cylinder row direction, and is a wall portion located downstream in the intake air flow direction among the wall portions constituting the intake collector 6. As shown in FIG.

The intake port 7 is bifurcated on the downstream side in the intake flow direction. The intake port 7 has a pair of downstream ends 9, 9 at its downstream end in the intake flow direction. A pair of downstream end portions 9, 9 are connected to a combustion chamber 11 (cylinder) of the internal combustion engine 1 via an intake valve 10, respectively. That is, the internal combustion engine 1 has two intake valves 10 in one cylinder. An upstream end portion 8 of each intake port 7 has a bell mouth portion 8a that widens toward the upstream side.

An intercooler 12 is arranged inside the intake collector 6 along the direction of the row of cylinders. The intercooler 12 cools the intake air compressed by the supercharger 5 to improve charging efficiency.

The intercooler 12 is set so that the internal pressure loss has a predetermined gradient so that the flow velocity distribution and pressure distribution of the intake air in each intake port 7 are uniform (uniform) under predetermined operating conditions. In other words, the intercooler 12 is set so that the internal pressure loss changes along the cylinder row direction.

More specifically, the intercooler 12 operates under the predetermined operating conditions even if the flow velocity distribution and pressure distribution of the intake air along the direction of the row of cylinders at the intercooler inlet 12a are not uniform (uniform). The flow velocity distribution and pressure distribution of the intake air along the direction of the cylinder row are uniform (uniform), and the flow velocity distribution and pressure distribution of the intake air in each intake port 7 are uniform (uniform). The pressure loss is set to have a predetermined gradient.

The flow of intake air from the intercooler outlet 12b to the cylinders is improved by uniformity (uniformity) in the flow velocity distribution and pressure distribution of the intake air along the direction of the row of cylinders at the intercooler outlet 12b. It becomes more difficult to peel off.

The intercooler inlet portion 12a is the upstream end of the intercooler 12 in the intake air flow direction. The intercooler outlet portion 12b is the downstream end of the intercooler 12 in the intake air flow direction.

For example, as shown in FIG. 1, the intercooler 12 has a high pressure loss portion where the internal pressure loss is relatively high and a low pressure loss portion where the internal pressure loss is relatively low. It is configured to exist alternately along the

That is, in the specification of the present application, the fact that the pressure loss inside the intercooler 12 has a predetermined gradient means that the pressure loss inside the intercooler 12 is not uniform (uniform), and the pressure loss inside the intercooler 12 is This means that a high pressure loss portion and a low pressure loss portion are formed, and the pressure loss varies along the direction of the row of cylinders.

Intake air is introduced from one end side in the cylinder row direction to the intake collector 6 arranged along the cylinder row direction. Therefore, in the first embodiment, the pressure of the intake air in the intake collector 6 on the upstream side of the intercooler 12 along the row direction of the cylinders is the same at the end on the other end side and the central portion of the intake collector 6 in the row direction of the cylinders. The pressure of the flow becomes high, and the intake air is sucked at the part sandwiched between the end of the intake collector 6 on the other end side and the central part in the cylinder row direction and the part on the one end side of the central part of the intake collector 6 in the cylinder row direction. pressure is low. That is, in the intake collector 6, the flow velocity distribution and pressure distribution of the intake air along the direction of the row of cylinders on the upstream side of the intercooler are not uniform (uniform).

The pressure loss inside the intercooler 12 is set in consideration of the flow velocity distribution and pressure distribution of the intake air along the direction of the row of cylinders in the intake collector 6 on the upstream side of the intercooler 12 . For example, the pressure loss inside the intercooler 12 is set to be high at a position where the intake air flow speed is high or from a position where the intake air pressure is high, and from a position where the intake air flow speed is low or the intake pressure is low. Set it low where the intake air flows. In other words, the pressure loss inside the intercooler 12 is set high at locations where the flow velocity of intake air is high or at locations where the pressure of intake air is high at the intercooler inlet 12a, and at locations where the flow velocity of intake air is low at the intercooler inlet 12a. Or set it low in the place where the pressure of intake is low.

The predetermined operating condition is an operating condition in which the in-cylinder flow of the intake gas flowing in from the two intake valves 10 of the same cylinder is required to have line symmetry with respect to the cylinder center axis. This is an operating condition that requires gas flow (for example, tumble flow with the swirl component suppressed as much as possible). More specifically, the predetermined operating conditions are operating conditions for lean combustion in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, or operating conditions for lean combustion by EGR.

It should be noted that the flow velocity distribution and pressure distribution of the intake air in the intake collector 6 on the upstream side of the intercooler 12 along the direction of the row of cylinders vary depending on the shape of the intake collector 6, the inflow position of the intake air with respect to the intake collector 6, and the like. , may be different from the first embodiment described above.

The internal combustion engine 15 of the comparative example shown in FIG. 2 has substantially the same configuration as the internal combustion engine 1 of the present invention shown in FIG. There is. In FIG. 2, the same components as those of the internal combustion engine 1 shown in FIG. 1 are given the same reference numerals, and redundant explanations are omitted.

When the pressure loss inside the intercooler 12 is uniform (uniform) as in the comparative example shown in FIG. , and the pressure distribution, and the flow velocity distribution and pressure distribution of the intake along the direction of the row of cylinders in the intake collector 6 on the downstream side of the intercooler 12 are the same. That is, when the pressure loss inside the intercooler 12 is uniform (uniform), the flow velocity distribution and pressure distribution of the intake air along the direction of the row of cylinders in the intake collector 6 on the upstream side of the intercooler 12 are not uniform. As a result, the flow velocity distribution and pressure distribution of the intake air along the direction of the row of cylinders in the intake collector 6 on the downstream side of the intercooler 12 also become uneven.

If the flow velocity distribution and pressure distribution of the intake air in the intake collector 6 on the downstream side of the intercooler 12 are not uniform along the direction of the row of cylinders, the flow of intake air in the intake collector 6 on the downstream side of the intercooler 12 is greatly disturbed. Since the flow velocity distribution and pressure distribution of the intake air in each intake port 7 are not uniform, a flow rate difference occurs in the intake air flowing in from the intake valves 10, 10 of the same cylinder, and the flow of the intake gas in the cylinder is not as expected. There is a risk that it will not result in gas flow. It should be noted that the uneven flow velocity distribution and pressure distribution of the intake air in each intake port 7 may occur even if the cylinder distribution of the intake air is not uneven.

In the internal combustion engine 1 of the first embodiment described above, the pressure loss inside the intercooler 12 is set to have a predetermined gradient.

Specifically, in the intercooler 12, the flow velocity distribution and pressure distribution of the intake air along the direction of the row of cylinders of the intercooler outlet 12b are uniform (uniform) under a predetermined condition, and the intake air in each intake port 7 becomes uniform. The internal pressure loss is set to have a predetermined gradient so that the flow velocity distribution and pressure distribution are uniform (uniform).

As a result, in the internal combustion engine 1, a flow rate difference is less likely to occur in the intake air flowing into the combustion chamber 11 (inside the cylinder) from the intake valves 10, 10 of the same cylinder. For example, by generating a tumble flow with the swirl component suppressed as much as possible, it is possible to improve the combustion speed and the diluted combustion limit and the lean combustion limit.

In addition, since it is possible to generate a desired gas flow (for example, a tumble flow in which swirl components are minimized) in the combustion chamber 11, it is possible to improve the combustion stability of the internal combustion engine 1 under predetermined operating conditions. can.

Other embodiments of the present invention will be described below. The same reference numerals are assigned to the same components as those of the first embodiment described above, and overlapping descriptions are omitted.

A second embodiment of the present invention will be described with reference to FIG. FIG. 3 is an explanatory diagram schematically showing an internal combustion engine 21 according to a second embodiment of the invention.

The internal combustion engine 21 of the second embodiment has substantially the same configuration as the internal combustion engine 1 of the first embodiment described above. ) partition wall 22 . That is, the intake collector 6 has a plurality of (two) partition walls 22 partitioning the downstream side of the intercooler outlet portion 12b.

The partition wall 22 is formed to separate the upstream ends 8 of adjacent intake ports 7 .

In other words, the partition wall 22 is designed so that the intake air flows into the upstream end portion 8 of the intake port 7 only from the portion of the intercooler outlet portion 12b that faces the upstream end portion 8 of the intake port 7 . It partitions the space on the downstream side of the cooler 12 .

The partition wall 22 continues from the intercooler outlet 12 b to the upstream end 8 of the intake port 7 . The partition wall 22 has an intake upstream end 22a abutted against the intercooler outlet portion 12b and an intake downstream end 22b connected to the downstream side wall portion 6a of the intake collector 6 .

That is, the partition wall 22 partitions the downstream side of the intercooler outlet portion 12b so that the intake air flows into the upstream end portion 8 of the intake port 7 in the shortest distance linearly.

In other words, the upstream end 8 of each intake port 7 is directly connected to the intercooler outlet 12b.

Further, in the internal combustion engine 1 of the first embodiment described above, since the space downstream of the intercooler 12 of the intake collector 6 is not partitioned by the partition wall 22, the intake of the cylinder in the intake stroke of the intercooler outlet 12b is The flow of intake air from a portion of the port 7 that does not face the upstream end 8 to the upstream end 8 of the intake port 7 of the cylinder during the intake stroke becomes, for example, an S-shaped curving flow. , there is a possibility that the uneven flow velocity distribution and pressure distribution of the intake air in the intake port 7 cannot be suppressed.

Therefore, the internal combustion engine 21 of the second embodiment is partitioned so that the intake air flows into the upstream end portion 8 of the intake port 7 only from the portion of the intercooler outlet portion 12b facing the upstream end portion 8. By providing the wall 22, the intake air flows into the upstream end 8 of the intake port 7 linearly (in the shortest distance), and the deviation of the flow velocity distribution and pressure distribution of the intake air in the intake port 7 is eliminated. can be reliably suppressed.

A third embodiment of the present invention will be described with reference to FIG. FIG. 4 is an explanatory diagram schematically showing the intake collector 6 and the intercooler 12 of the internal combustion engine 31 in the third embodiment of the invention.

The internal combustion engine 31 of the third embodiment has substantially the same configuration as the internal combustion engine 21 of the second embodiment described above, but a through hole 32 is formed in the partition wall 22, and the through hole 32 can be opened and closed. a control valve 33.

A through hole is formed in each partition wall 22 . A control valve 33 is provided in each through hole 32 . The control valves 33, 33 are fixed to a rotating shaft 34 extending in the direction of the row of cylinders, and the through holes 32, 32 are opened and closed at the same time by rotating the rotating shaft 34 by an actuator (not shown) or the like. The control valves 33, 33 may be individually opened and closed.

The control valve 33 is controlled so as to close the through hole 32 when carrying out lean combustion in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio or dilution combustion by EGR.

Further, the control valve 33 is controlled so as to open the through hole 32 during high-output operation. When the dilution combustion described above is not performed, the control valve 33 may be controlled to open the through hole 32 regardless of whether the output is high or low.

If the intake collector 6 is provided with the partition wall 22 on the downstream side of the intercooler 12, there is a risk that the pressure loss will greatly increase in the high supercharging region where high power operation is performed.

The high supercharging region where the supercharging pressure is equal to or higher than a predetermined value is an operating region where it is desirable to reduce the pressure loss and push air into the cylinder. , the need for partition walls 22 is low.

Therefore, the internal combustion engine 31 is provided with a through hole 32 in the partition wall 22, and further with a control valve 33 capable of opening and closing the through hole 32, so that the control valve 33 is opened in a high supercharging region and the through hole 32 is By opening the , the pressure loss of the intake collector 6 can be reduced.

In addition, when the in-cylinder flow demand for the intake gas in the combustion chamber 11 is large (for example, when performing lean combustion in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, or dilution combustion by EGR), the internal combustion engine 31 controls the control valve By closing the valve 33 to block the through hole 32, the flow velocity distribution and pressure distribution of the intake air in the intake port 7 can be made uniform (uniform).

Although specific embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

The internal combustion engines 1, 21, 31 of the present invention are essentially designed so that there is no flow rate difference between the intake air flowing from the intake valves 10, 10 of the same cylinder, and the intake gas in the combustion chamber 11 (inside the cylinder) is It generates a constant gas flow (for example, a tumble flow with the swirl component suppressed as much as possible). Therefore, in the internal combustion engines 1, 21, and 31, if the flow velocity distribution and pressure distribution of the intake air flowing into the upstream end portion 8 of each intake port 7 are uniform (uniform), the intake air that has passed through the intercooler 12 The pressure does not have to be uniform (uniform) along the cylinder row direction. That is, the pressure loss inside the intercooler 12 is such that the intake pressure of the intake air passing through the intercooler 12 increases in the cylinder row direction in order to make the flow velocity distribution and pressure distribution of the intake air in each intake port 7 uniform (uniform). may be set so as not to be uniform (uniform) along the .

In each of the above-described embodiments, the internal combustion engines 1, 21, 31 have two intake valves 10, 10 in one cylinder, but the present invention has three or more intake valves in one cylinder. It is also applicable to an internal combustion engine with

The internal combustion engines 1, 21, and 31 in each of the embodiments described above are in-line three-cylinder engines, but the present invention is also applicable to multi-cylinder internal combustion engines other than three-cylinder internal combustion engines and single-cylinder internal combustion engines.

Reference Signs List 1 Internal combustion engine 2 Intake passage 3 Throttle valve 4 EGR passage 5 Supercharger 6 Intake collector 6a Downstream side wall portion 7 Intake port 8 Upstream end 8a Bell mouth portion 9 Downstream end Portions 10: Intake valve 11: Combustion chamber 12: Intercooler 12a: Intercooler inlet 12b: Intercooler outlet 21: Internal combustion engine 22: Partition wall 22a: Intake upstream end 22b: Intake downstream end 31: Internal combustion engine 32 ... Through hole 33 ... Control valve 34 ... Rotating shaft

Claims (9)

a supercharger for compressing intake air;
an intake collector located downstream of the supercharger and distributing intake air to intake ports of each cylinder;
a plurality of intake valves provided in one cylinder;
an intercooler disposed inside the intake collector;
The intercooler is set so that the internal pressure loss has a predetermined gradient ,
The intake collector has a plurality of partitions that partition the downstream side of the outlet portion of the intercooler so that the intake air flows into the inlet portion of the intake port only from the portion of the outlet portion of the intercooler that faces the inlet portion. having a partition wall,
A through hole is formed in the partition wall,
An internal combustion engine , wherein the through hole is provided with a control valve capable of opening and closing the through hole . 2. The internal combustion engine according to claim 1, wherein the predetermined gradient is set so that the flow velocity distribution of intake air in each intake port becomes uniform under predetermined operating conditions. 3. The apparatus according to claim 2, wherein the predetermined gradient is set so that the flow velocity distribution of the intake air at the outlet of the intercooler is uniform along the direction of the row of cylinders under the predetermined operating conditions. internal combustion engine. 4. The internal combustion engine according to claim 2, wherein the predetermined operating condition is an operating condition in which the in-cylinder flow of the intake gas flowing in from each intake valve of the same cylinder is required to have symmetry with respect to the cylinder center axis. institution. The internal combustion engine according to any one of claims 2 to 4, wherein the predetermined operating condition is an operating condition for lean combustion in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, or an operating condition for lean combustion by EGR. The internal combustion engine according to any one of claims 1 to 5, wherein the intercooler is set so that the internal pressure loss changes along the direction of the row of cylinders. 7. The control valve according to any one of claims 1 to 6, wherein the control valve closes the through-hole when carrying out lean combustion in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio or diluted combustion by EGR. internal combustion engine. 8. The internal combustion engine according to claim 7 , wherein the control valve opens the through hole when the dilution combustion is not performed. The internal combustion engine according to any one of claims 1 to 8, wherein the control valve opens the through hole when performing high-power operation.

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