JP4367327B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to a multi-cylinder internal combustion engine having two banks and each cylinder in each bank exploding at unequal intervals.

  2. Description of the Related Art Conventionally, there is a so-called V-type multi-cylinder internal combustion engine having two banks and a plurality of cylinders arranged in each bank.

  In general, in a multi-cylinder internal combustion engine, the firing order of each cylinder is determined so as to satisfy various requirements such as equal combustion between the cylinders and no torsional vibration in the crankshaft. It is done. For example, in order to satisfy the requirements in a V-type 8-cylinder internal combustion engine in which the first cylinder, the second cylinder,..., The eighth cylinder are alternately arranged from the left and right from the front of the engine in the left bank, the first cylinder → 8 In general, ignition is performed at every crank angle of 90 ° CA in the order of No. cylinder → No. 7 cylinder → No. 3 cylinder → No. 6 cylinder → No. 5 cylinder → No. 4 cylinder → No. 2 cylinder. Thus, in this V-type 8-cylinder internal combustion engine, the ignition and explosion of each cylinder in the left and right banks are at unequal intervals.

  On the other hand, in a V-type multi-cylinder internal combustion engine, combustion gas is discharged from each cylinder to an exhaust manifold outside the engine provided for each of the left and right banks. Therefore, in the above-described V-type multi-cylinder internal combustion engine that performs ignition and explosion at unequal intervals, exhaust interference occurs due to a difference in exhaust pulsation between specific cylinders, thereby causing internal EGR (combustion chamber) between the cylinders. Therefore, the intake air charging efficiency between the cylinders (in other words, the air-fuel ratio) varies.

  In view of this, Japanese Patent Application Laid-Open No. H10-228561 discloses a technique for making the internal EGR amount uniform between the cylinders by making the shape of the collection portion of the exhaust manifold an ejector shape.

  Incidentally, it is generally known that the internal EGR lowers the combustion temperature and reduces the discharge amount of HC and NOx. It is also known that the internal EGR can reduce pump loss and reduce the fuel consumption rate. For this reason, in a conventional internal combustion engine, by providing a valve overlap period (a period in which the intake valve and the exhaust valve are simultaneously open) between the exhaust stroke and the intake stroke, the internal EGR amount is increased, and HC and It aims to reduce NOx emissions and fuel consumption.

  However, if the valve overlap period is provided in a V-type multi-cylinder internal combustion engine, in each cylinder arranged in the same bank, the valve overlap period of a certain cylinder and the blow-down timing of exhaust of a specific cylinder (exhaust valve Therefore, the difference in exhaust pulsation between the two cylinders causes a difference in the internal EGR amount between the cylinders.

  Taking the V-type 8-cylinder internal combustion engine that is ignited in the above-mentioned ignition sequence as an example, the effects of blowdown gas in the 7th and 5th cylinders of the same bank are applied to the 1st and 3rd cylinders of the left bank. The internal EGR amount increases in response to each, and the internal EGR amount is influenced by the blowdown gas of the 4th and 8th cylinders of the same bank in the 6th and 2nd cylinders of the right bank. Become more.

  For this reason, in Patent Document 2 below, the internal EGR amount is reduced by changing the shape of the exhaust cam between the cylinder having a large internal EGR amount and the cylinder having a small internal EGR amount, thereby reducing the overlapping state of the valve overlap period and the blowdown time. The technique which aims at equalization of this is disclosed.

JP-A-3-70810 Special table 2003-515025 gazette

  However, even if the shape of the manifold portion of the exhaust manifold is changed to an ejector shape as in the above-mentioned Patent Document 1, the internal EGR amount between the cylinders is not sufficiently uniform. Therefore, variations in intake air charging efficiency (air-fuel ratio) between specific cylinders cannot be eliminated, and combustion fluctuations occur between the cylinders, leading to a reduction in shaft torque due to the unstable combustion. End up. Further, due to the difference in the internal EGR amount between the cylinders, the valve overlap period is limited to the combustion limit of the cylinder having a large internal EGR amount and cannot be expanded. The effect of reduction and reduction in fuel consumption rate cannot be achieved.

  Further, in Patent Document 2, it is difficult to extend the valve overlap period, and even if the shaft torque can be improved, the effects of reducing the discharge amount of HC and NOx and lowering the fuel consumption rate can be sufficiently obtained. I can't.

  Thus, conventionally, since it is difficult to expand the valve overlap period, it is not possible to achieve both improvement in shaft torque by stabilizing combustion, reduction in HC and NOx emissions, and reduction in fuel consumption rate, It was not possible to meet the conflicting demands of recent improvements in engine performance and environmental performance.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an internal combustion engine provided with a means for equalizing an internal EGR amount between cylinders, which can improve the disadvantages of the conventional example and can extend a valve overlap period. .

In order to achieve the above object, according to the first aspect of the present invention, in an internal combustion engine having two banks and causing each cylinder on the same bank to explode at unequal intervals, the valve overlap period is the exhaust of other cylinders. A flow path opening / closing valve capable of opening and closing a flow path of an exhaust passage in the first cylinder that does not overlap with a valve opening timing, and capable of increasing an exhaust pressure of the first cylinder by reducing a valve opening degree; By reducing the valve opening degree of the flow path opening / closing valve provided only on the exhaust passage of the first cylinder, the internal EGR amount in the first cylinder can be reduced more than when the valve opening degree of the flow path opening / closing valve is fully open. The internal EGR amount between the first cylinder and the second cylinder is increased by increasing the exhaust amount of exhaust gas in the second cylinder which is increased and the valve overlap period overlaps with the opening timing of the exhaust valves of the other cylinders. Reduce the variation of It is provided with control means to equalize the internal EGR amount between the gas cylinder, the.

According to the invention described in the claim 1, whereas by increasing the exhaust pressure of the first cylinder (blowdown gas generating cylinder), an internal EGR amount of the first cylinder is increased, the pressure of the blowdown gas The wave is attenuated, and the arrival time of the positive pressure wave at the other cylinder can be delayed. For this reason, the amount of exhaust gas exhausted from the second cylinder (blowdown gas inflow cylinder) whose internal EGR amount increases due to the effect of blowdown gas increases, and the variation in internal EGR amount between the respective cylinders is reduced. Alternatively, the variation in intake air charging efficiency (air-fuel ratio) between the cylinders is small or uniform.

  In the internal combustion engine according to the present invention, variation in intake air charging efficiency (air-fuel ratio) between cylinders can be reduced or made uniform, so that shaft torque can be improved. Further, since the variation in intake air charging efficiency (air-fuel ratio) between the cylinders can be kept small or uniform even when the valve overlap period is expanded, the inside of the valve overlap period can be increased. The amount of EGR can be increased, and the emission amount of HC and NOx can be reduced and the fuel consumption rate can be reduced.

  Embodiments of an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

  A first embodiment of an internal combustion engine according to the present invention will be described with reference to FIGS. Here, reference numeral 1 in FIG. 1 indicates the internal combustion engine of the first embodiment.

  First, the configuration of the internal combustion engine 1 of the first embodiment will be described.

The internal combustion engine 1 of the first embodiment has two banks, and the first cylinder # 1, the second cylinder # 2,..., The eighth cylinder alternately from the left and right from the front of the left bank (the left side in FIG. 1). This is a so-called V-type eight-cylinder internal combustion engine in which cylinder # 8 is arranged, and includes a V-shaped cylinder block 1a and two cylinder heads 1b _LH and 1b _RH . That is, the V-type 8-cylinder internal combustion engine 1 of the first embodiment is provided with the first cylinder # 1, the third cylinder # 3, the fifth cylinder # 5, the seventh cylinder # 7 in one bank, No. 2 cylinder # 2, No. 4 cylinder # 4, No. 6 cylinder # 6, No. 8 cylinder # 8 are provided in this bank.

Here, in the internal combustion engine 1 of the first embodiment, as shown in FIG. 1, the intake manifold 2 is disposed between the left and right banks, while the exhaust manifolds 3 _LH , 3 are disposed outside the engines of the respective banks. _An exhaust path composed of _RH or the like is arranged.

As to the intake manifold 2 of the present embodiment 1 is an intake passage 2 _{# 21} to # ₈ of the 8 is provided from the first directing air from outside into the cylinder # 1 to # 8 respectively, of the respective Air whose intake amount is adjusted by the throttle valve 2a shown in FIG. 1 is sucked into the cylinders # 1 to # 8 through the intake passages 2 _{# 1 to} 2 _{# 8} .

  Next, the exhaust path of the first embodiment will be described in detail.

First, on the side of one bank (hereinafter referred to as “left bank”) having the first cylinder # 1, the third cylinder # 3, the fifth cylinder # 5, and the seventh cylinder # 7, each cylinder # 1 is provided. , # 3, # 5, # 7, exhaust manifold 3 _LH , first and second catalyst devices 4 _LH , 5 _LH arranged on the downstream side of the exhaust manifold 3 _LH , and the first and second There are provided a first exhaust pipe 6 _LH for communicating the two catalyst devices 4 _LH and 5 _LH and a second exhaust pipe 7 _LH into which the exhaust gas having passed through the second catalyst device 5 _LH flows.

On the other hand, on the other bank (hereinafter referred to as “right bank”) side having the second cylinder # 2, the fourth cylinder # 4, the sixth cylinder # 6, and the eighth cylinder # 8, the respective cylinders similarly. Exhaust manifold 3 _RH communicating with # 2, # 4, # 6, and # 8, first and second catalytic devices 4 _RH and 5 _RH arranged downstream of the exhaust manifold 3 _RH , and the first And a first exhaust pipe 6 _RH for communicating the second catalyst devices 4 _RH and 5 _RH , and a second exhaust pipe 7 _RH into which exhaust gas having passed through the second catalyst device 5 _RH flows.

Each of the first exhaust pipes 6 _LH and 6 _RH is assembled in one path, and one catalyst device is arranged in place of the two second catalyst devices 5 _LH and 5 _RH on the downstream side of the gathered portion. May be.

Here, the exhaust manifold 3 _LH in the left bank in the first embodiment is connected to the first to fourth exhaust passages 3 _{# 1} and 3 _# individually communicating with the respective cylinders # 1, # 3, # 5, and # 7. ₃ , 3 _{# 5} , 3 _{# 7} and a collective passage 3a ₁ for collecting the exhaust gases of these first to fourth exhaust passages 3 _{# 1} , 3 _{# 3} , 3 _{# 5} , 3 _{# 7} in one path It is configured. On the other hand, the exhaust manifold 3 _RH in the right bank has first to fourth exhaust passages 3 _{# 2} , 3 _{# 4} , 3 _{# 6} individually communicating with the respective cylinders # 2, # 4, # 6, # 8. , 3 _{# 8} and a collecting passage 3a ₂ for collecting the exhaust gases of the first to fourth exhaust passages 3 _{# 2} , 3 _{# 4} , 3 _{# 6} , 3 _{# 8} in one route.

  By the way, the ignition order of the internal combustion engine 1 of the first embodiment is determined so as to satisfy various requirements such as equal combustion of the cylinders # 1 to # 8. For example, here, the first cylinder # 1 → 8th cylinder # 8 → 7th cylinder # 7 → 3rd cylinder # 3 → 6th cylinder # 6 → 5th cylinder # 5 → 4th cylinder # 4 → 2nd cylinder An example is given in which ignition is performed every crank angle of about 90 ° CA in the order of # 2.

  When ignition is performed in such an ignition sequence, the ignition / explosion intervals of the respective cylinders # 1, # 3, # 5, # 7 in the left bank, and the respective cylinders # 2, # 4, # 6 in the right bank , # 8 ignition / explosion intervals are unequal, and the internal EGR amount varies due to exhaust interference between specific cylinders, resulting in variations in intake air charging efficiency (air-fuel ratio) between the cylinders. End up.

  That is, in general, in an internal combustion engine, a valve overlap period in which an intake valve and an exhaust valve are simultaneously opened is set, and a period in which a valve overlap period of a certain cylinder and an exhaust blowdown timing of a specific cylinder overlap. Exists. For this reason, exhaust interference occurs due to the difference in exhaust pulsation between the cylinders, and this causes a difference in the internal EGR amount, resulting in variations in the charging efficiency (air-fuel ratio) of intake air.

  For example, in the V-type eight-cylinder internal combustion engine 1, as shown in FIG. 2-1, between the first cylinder # 1 and the seventh cylinder # 7 and between the third cylinder # 3 and the fifth cylinder # 5. , There is a state in which the exhaust valve is open at the same time between the sixth cylinder # 6 and the fourth cylinder # 4 and between the second cylinder # 2 and the eighth cylinder # 8. For this reason, when the exhaust valves of the seventh cylinder # 7, the fifth cylinder # 5, the fourth cylinder # 4 and the eighth cylinder # 8 are opened, the pressure wave of the blowdown gas is in the valve overlap period. No. 1 cylinder # 1, No. 3 cylinder # 3, No. 6 cylinder # 6 and No. 2 cylinder # 2 reach, and exhaust interference occurs due to the difference in exhaust pulsation between the respective cylinders. As a result, exhaust from the first cylinder # 1, third cylinder # 3, sixth cylinder # 6, and second cylinder # 2 is not sufficiently performed, so the internal EGR amount between the respective cylinders differs. And the intake air charging efficiency (air-fuel ratio) varies.

  Also, in recent internal combustion engines, the opening and closing timings of the intake valve and the exhaust valve are set in order to reduce the HC and NOx emission amount and the fuel consumption rate by increasing the internal EGR amount of each cylinder. Means such as a so-called variable valve timing mechanism that can be varied are provided, and a suitable valve overlap period is variably set as appropriate. Therefore, when such means as a variable valve timing mechanism is provided in each cylinder # 1 to # 8 in the V-type 8-cylinder internal combustion engine 1, and the valve overlap period is expanded as shown in FIG. The difference in internal EGR amount occurs between the same cylinders as described above, and the intake air charging efficiency (air-fuel ratio) varies greatly.

  Hereinafter, the cylinders # 4, # 5, # 7, and # 8 in which the amount of internal EGR is reduced by generating blowdown gas under the respective circumstances are also referred to as “blowdown gas generating cylinders” as appropriate. In addition, the cylinders # 6, # 3, # 1, and # 2 whose internal EGR amount increases under the influence of the blowdown gas under the respective circumstances are also referred to as “blowdown gas inflow cylinders” as appropriate.

  As described above, in the V-type 8-cylinder internal combustion engine 1, the intake air charging efficiency (air-fuel ratio) varies between the cylinders due to the difference in the internal EGR amount between the cylinders. The torque cannot be improved, and the valve overlap period cannot be extended.

Therefore, in the first embodiment, in order to suppress variation in the charging efficiency (air-fuel ratio) of the intake air among the cylinders, the blow-down gas generating cylinder # 4 having a small internal EGR amount and a high volumetric efficiency ηV. Intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} , 8 _{# 8} shown in FIG. 1 for variably controlling the intake pressures of _{# 5} , _{# 7} , and _{# 8} are provided.

The intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} and 8 _{# 8} are respectively connected to the fourth intake passage 2 _{# 4} and the fourth intake passage 2 _{# 4} and # 8 related to the blowdown gas generating cylinders # 4, # 5, # 7 and # 8. 5 intake passages 2 _{# 5} , 7th intake passage 2 _{# 7} and 8th intake passage 2 _{# 8} are flow path opening / closing valves respectively, and each intake passage 2 _{# 4} , 2 _{# 5} , 2 _{# 7} , 2 _{# 8} can be varied steplessly from fully open to fully closed. The intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} , and 8 _{# 8} do not necessarily need to be steplessly variable from the fully open state to the fully closed state. To the fully closed state may be variable step by step.

Here, the opening / closing operations of the intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} and 8 _{# 8} are controlled by an electronic control unit (ECU) 9 shown in FIG. Specifically, the electronic control unit 9 is configured to increase the volumetric efficiency ηV of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 and the blowdown gas in which the internal EGR amount increases due to the influence of the respective blowdown gases. Each intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 is used so that the variation between the volumetric efficiency ηV of the inflow cylinders # 6, # 3, # 1, and # 2 is reduced (preferably the same). _# 7,8 Adjust the valve opening of _{# 8} .

  Here, since the internal EGR amount in one cylinder differs according to the engine speed and the load, the above-described difference in the internal EGR amount between the cylinders also differs depending on the engine speed and the load.

For this reason, in the first embodiment, the valve opening degree corresponding to the engine speed and the load is obtained through experiments, simulations, and the like, and the corresponding relationship is prepared in advance as map data. Then, the electronic control unit 9 obtains the valve opening from the map data based on the engine speed and load when opening the intake valves of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8, The respective intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} and 8 _{# 8} are controlled so as to achieve the valve opening.

  By the way, the influence of the blowdown gas described above is more likely to be received as the valve opening time at the same time of the respective exhaust valves between the cylinders is longer, and is less likely to be received if the time is shorter. That is, if it is operating at low / medium speed rotation, it will be susceptible to blowdown gas, but if it is operating at high speed rotation, it will be less susceptible to that effect.

For this reason, the electronic control unit 9 according to the first embodiment appropriately sets the low / medium speed rotation region shown in FIG. 3 (here, it is set to 3000 rpm or less, but depending on the specifications of the internal combustion engine 1 or the like, 4000 rpm or less). ) To throttle the valve opening of the intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} , 8 _{# 8} , and in the high speed range, the intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} , 8 Fully open _{# 8} . Hereinafter, the region in which the throttle opening operation of the intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} , and 8 _{# 8} is performed is referred to as “intake pressure control means operation region”.

  The operation will be described below with reference to the flowchart of FIG.

  First, the electronic control unit 9 determines whether or not it is in the intake pressure control means operating region based on the information on the engine speed (step ST1).

Here, if the electronic control unit 9 is not in the intake pressure control means operating region (that is, in the high speed rotation region), it returns to step ST1 and the intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{#. 7} , 8 Monitor _{# 8} for necessity.

On the other hand, in the intake pressure control means operating region (that is, the low / medium speed rotation region), the electronic control unit 9 determines the corresponding blowdown gas generating cylinder # 4 based on the engine speed and load at that time. The valve opening degree of the intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} , 8 _{# 8} related to # 5, # 7, # 8 is obtained from the map data (step ST2).

Thereafter, the electronic control unit 9 adjusts the intake pressure control means 8 _{# 4} , 8 _{# 5 for} the corresponding blowdown gas generation cylinders # 4, # 5, # 7, # 8 so that the obtained valve opening is obtained. , 8 _{# 7} and 8 _{# 8} are controlled (step ST3).

As a result, the fourth intake passage 2 _{# 4} , the fifth intake passage 2 _{# 5} , the seventh intake passage 2 _{# 7,} or the seventh intake passage relating to the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 to be controlled Eight intake passages 2 _{# 8} are throttled, and the intake pressure decreases (in other words, the intake air amount decreases) as shown by the wavy line in FIG. Then, the volumetric efficiency ηV of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 is lowered, and the volumetric efficiency ηV of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 and the blowdown gas are blown. Variations between the volumetric efficiency ηV of the down gas inflow cylinders # 6, # 3, # 1, and # 2 are reduced (or the same). In other words, the variation in the amount of internal EGR between the cylinders becomes small (or uniform).

FIG. 5 is a diagram showing the pressure waveforms of the exhaust pulsation and the intake pulsation during a valve overlap period of a cylinder, and the intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} , 8 _{# 8} It is a figure shown about the difference in the pressure waveform of intake pulsation at the time of a full opening and the time of operation.

  Thereafter, the electronic control unit 9 returns to step ST1 and repeats the same operation.

Thus, by providing the intake pressure control means 8 _{# 4} , 8 _{# 5} , 8 _{# 7} , 8 _{# 8} to the blowdown gas generating cylinders # 4, # 5, # 7, # 8, respectively, Variations in intake air charging efficiency (air-fuel ratio) between the cylinders can be reduced (or made the same), thereby improving the shaft torque. Furthermore, since the intake air charging efficiency (air-fuel ratio) variation can be kept small (or uniform) even if the valve overlap period is expanded, the internal EGR amount due to the expansion of the valve overlap period can be maintained. The increase can be achieved, and the emission amount of HC and NOx can be reduced and the fuel consumption rate can be reduced.

  Next, a second embodiment of the internal combustion engine according to the present invention will be described with reference to FIG. Here, reference numeral 11 in FIG. 6 indicates the internal combustion engine of the second embodiment.

The internal combustion engine 11 of the second embodiment has a cylinder block 11a in which eight cylinders # 1 to # 8 are arranged in the left and right banks and two cylinder heads in the same positional relationship as the internal combustion engine 1 of the first embodiment. This is a V-type 8-cylinder internal combustion engine that includes 11b _LH and 11b _RH , and in which each cylinder # 1 to # 8 is ignited in the same ignition sequence.

Also in the second embodiment, as shown in FIG. 6, the intake manifold 12 is disposed between the left and right banks, while the exhaust path including the exhaust manifolds 13 _LH and 13 _{RH is provided} outside the engine of each bank. Is placed.

First, the intake manifold 12 of the second embodiment includes first to eighth intake passages 12 _{# 1 to} 12 _{# 8} similar to the intake manifold 2 of the first embodiment, and each intake passage 12 _{# 1} thereof. air intake amount is adjusted by the throttle valve 12a shown in FIG. 6 through 12 # ₈ leads to each cylinder # 1 to # 8.

On the other hand, the exhaust path of the second embodiment is the same as the exhaust path of the first embodiment, the exhaust manifold 13 _LH , the first and second catalytic devices 14 _LH and 15 _LH and the first and second catalyst devices on the left bank side. Exhaust pipes 16 _LH and 17 _LH are provided, and an exhaust manifold 13 _RH , first and second catalyst devices 14 _RH and 15 _RH , and first and second exhaust pipes 16 _RH and 17 _RH are provided on the right bank side. However, in the second embodiment, the types of the exhaust manifolds 13 _LH and 13 _RH are changed as follows. Each of the first exhaust pipes 16 _LH and 16 _RH is gathered in one path, and one catalyst device is arranged in place of the two second catalyst devices 15 _LH and 15 _RH on the downstream side of the gathered portion. May be.

Specifically, the exhaust manifold 13 _{LH in} the left bank of the second embodiment has first to fourth exhausts individually communicating with the cylinders # 1, # 3, # 5, and # 7 as shown in FIG. a passage 13 _# 1, ₁₃ # 3, 13 _# 5, 13 _{# 7,} the first collecting passage 13a ₁ to assemble the first and second exhaust passages 13 _# 1, 13 _{# 3} of the exhaust gas to one path , The second collecting passage 13b ₁ for collecting the exhaust gases of the third and fourth exhaust passages 13 _{# 5} and 13 _{# 7} in one path, and the exhaust of the first and second collecting passages 13a ₁ and 13b ₁ The third collecting passage 13c ₁ is configured to collect gas in one path.

On the other hand, as shown in FIG. 6, the exhaust manifold 13 _RH in the right bank has first to fourth exhaust passages 13 _{# 2} and 13 _# individually communicating with the respective cylinders # 2, # 4, # 6, and # 8. ₄ , 13 _{# 6} , 13 _{# 8} , the first collecting passage 13 a ₂ for collecting the exhaust gases of the first and second exhaust passages 13 _{# 2} , 13 _{# 4} in one path, and the third and fourth The second collecting passage 13b ₂ for collecting the exhaust gas in the exhaust passages 13 _{# 6} and 13 _{# 8} in one path, and the exhaust gas in the first and second collecting passages 13a ₂ and 13b ₂ are collected in one path. It is composed of a third collecting passage 13c _2.

That is, in the internal combustion engine 1 of the first embodiment, so-called 4-1 type exhaust manifolds 3 _LH and 3 _RH are used, but in the second embodiment, a so-called 4-2-1 type exhaust manifold 13 _{LH is used.} 13 _RH is used.

By the way, even when the shapes of the exhaust manifolds 13 _LH and 13 _RH are different as described above, exhaust interference due to the influence of the blow-down gas occurs between the same cylinders as in the first embodiment.

For this reason, even in the second embodiment, as in the first embodiment, the intake pressures of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 having a small internal EGR amount and a high volumetric efficiency ηV are variable. Intake pressure control means 18 _{# 4} , 18 _{# 5} , 18 _{# 7} and 18 _{# 8} shown in FIG.

The intake pressure control means 18 _{# 4} , 18 _{# 5} , 18 _{# 7} , and 18 _{# 8} of the second embodiment are the fourth intake passages related to the blowdown gas generating cylinders # 4, # 5, # 7, and # 8. 12 _{# 4} , 5th intake passage 12 _{# 5} , 7th intake passage 12 _{# 7} and 8th intake passage 12 _{# 8} , each provided with a channel opening / closing valve, each intake passage being fully closed from the fully open state It can be changed steplessly to the state. Each intake pressure control means 18 _{# 4} , 18 _{# 5} , 18 _{# 7} , 18 _{# 8} does not necessarily have to be variable steplessly from the fully open state to the fully closed state. To the fully closed state may be variable step by step.

Here, the intake pressure control means 18 _{# 4} , 18 _{# 5} , 18 _{# 7} , and 18 _{# 8} are also opened and closed by the electronic control unit (ECU) 19 shown in FIG. Operation is controlled. That is, when the electronic control unit 19 determines that the intake pressure control means operating region (that is, the low / medium speed rotation region), the volume efficiency ηV of the blowdown gas generating cylinders # 4, # 5, # 7, # 8 is determined. And the volumetric efficiency ηV of the blowdown gas inflow cylinders # 6, # 3, # 1, and # 2 in which the internal EGR amount increases due to the respective blowdown gases are small (preferably the same) ), The valve opening degree of each intake pressure control means 18 _{# 4} , 18 _{# 5} , 18 _{# 7} , 18 _{# 8} is adjusted using the engine speed, load and map data.

  Therefore, even in the second embodiment, similarly to the first embodiment, the variation in the charging efficiency (air-fuel ratio) of the intake air between the respective cylinders can be reduced (or made the same). The shaft torque can be improved. Furthermore, since the intake air charging efficiency (air-fuel ratio) variation can be kept small (or uniform) even if the valve overlap period is expanded, the internal EGR amount due to the expansion of the valve overlap period can be maintained. The increase can be achieved, and the emission amount of HC and NOx can be reduced and the fuel consumption rate can be reduced.

  Next, a third embodiment of the internal combustion engine according to the present invention will be described with reference to FIG. Here, reference numeral 21 in FIG. 7 indicates the internal combustion engine of the third embodiment.

The internal combustion engine 21 of the third embodiment includes a cylinder block 21a in which eight cylinders # 1 to # 8 are arranged in the left and right banks and two cylinder heads in the same positional relationship as the internal combustion engine 1 of the first embodiment. This is a V-type 8-cylinder internal combustion engine that includes 21b _LH and 21b _RH , and in which each cylinder # 1 to # 8 is ignited in the same ignition sequence.

Also in the third embodiment, as shown in FIG. 7, the intake manifold 22 is disposed between the left and right banks, while the exhaust path including the exhaust manifolds 23 _LH and 23 _{RH is provided} outside the engine of each bank. Is placed.

The intake manifold 22 of the third embodiment includes first to eighth intake passages 22 _{# 1 to} 22 _{# 8} that are the same as the intake manifold 2 of the first embodiment, and each of the intake passages 22 _{# 1} to 22 _{# 1} to 22. The air whose intake amount is adjusted by the throttle valve 22a shown in FIG. 7 is guided to the cylinders # 1 to # 8 via 22 _{# 8} .

As in the first embodiment, the exhaust path of the third embodiment also has exhaust manifolds 23 _LH , first and second catalyst devices 24 _LH and 25 _LH , and first and second exhausts on the left bank side. Pipes 26 _LH and 27 _LH are provided, and an exhaust manifold 23 _RH , first and second catalyst devices 24 _RH and 25 _RH , and first and second exhaust pipes 26 _RH and 27 _RH are provided on the right bank side. Is provided. The first exhaust pipes 26 _LH and 26 _RH are gathered in one path, and one catalyst device is arranged in place of the two second catalyst devices 25 _LH and 25 _RH on the downstream side of the gathered portion. May be.

Here, as the exhaust manifolds 23 _LH and 23 _RH of the third embodiment, the same 4-1 type as in the first embodiment is used. That is, on the left bank side, the first to fourth exhaust passages 23 _{# 1} , 23 _{# 3} , 23 _{# 5} , 23 _{# 7} and the collecting passage 23a ₁ constitute an exhaust manifold 23 _LH , and the right bank in the side, _# 2 fourth exhaust passage 23 from the first, 23 _# 4, 23 _# 6, 23 _{# 8} and _RH exhaust manifold 23 at a set passage 23a ₂ is formed.

  In the first and second embodiments described above, the intake pressure of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 is adjusted in order to avoid inconvenience due to the influence of the blowdown gas. In Example 3, such inconvenience is avoided by adjusting the exhaust pressure of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8.

Specifically, in the third embodiment, each of the exhaust manifolds 23 _LH and 23 _RH related to the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 having a small internal EGR amount and a high volumetric efficiency ηV. Exhaust pressure shown in FIG. 7 is used to variably control the exhaust pressure of each of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 in the exhaust passages 23 _{# 4} , 23 _{# 5} , 23 _{# 7} , and 23 _{# 8} . Control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} and 28 _{# 8} are provided.

The exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} , and 28 _{# 8} are configured so that the exhaust passages 23 _{# 4} , 23 _{# 5} , 23 _{# 7} , and 23 _{# 8} are fully opened to fully closed. A flow-path on-off valve that can be changed steplessly, and is controlled by the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 and their respective blowdown gases by adjusting the valve opening. The variation in the internal EGR amount between the blowdown gas inflow cylinders # 6, # 3, # 1, and # 2 in which the EGR amount increases is reduced (preferably the same).

More specifically, each of the exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} , 28 _{# 8} has a respective exhaust passage 23 _{# 4} , 23 _{# 5} , 23 _{# 7} , 23 _{# 8} . The exhaust pressure of each blowdown gas generating cylinder # 4, # 5, # 7, # 8 is raised by narrowing down, in other words, it functions as a blowdown gas generating cylinder exhaust pressure adjusting means.

The exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} and 28 _{# 8} do not necessarily have to be variable steplessly from the fully open state to the fully closed state. To the fully closed state may be variable step by step.

The exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} , and 28 _{# 8} are controlled by an electronic control unit (ECU) 29 shown in FIG. 7 as control means. For this reason, even in the third embodiment, the valve opening degree corresponding to the engine speed and the load is obtained through experiments, simulations, and the like, and the corresponding relationship is prepared in advance as map data. Then, the electronic control unit 29 obtains the valve opening from the map data based on the engine speed and load when the exhaust valves of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 are opened. The exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} , and 28 _{# 8} are controlled so that the valve opening becomes the same.

Further, for the same reason as that of the first embodiment, the electronic control device 29 is set to a low / medium speed rotation region shown in FIG. The valve opening degree of the exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} , 28 _{# 8} is throttled by the above, and the exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 in the high speed rotation range. Fully open _{# 7} and 28 _{# 8} . Hereinafter, the region in which the exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} , and 28 _{# 8} perform the throttle operation is referred to as “exhaust pressure control means operating region”. Here, “intake pressure control means operating region” shown in FIG. 3 is read as “exhaust pressure control means operating region”.

  The operation will be described below with reference to the flowchart of FIG.

  First, the electronic control unit 29 determines whether or not the exhaust pressure control means operating region is based on the information on the engine speed (step ST11).

Here, if the electronic control unit 29 is not in the exhaust pressure control means operating region (that is, in the high speed rotation region), the electronic control device 29 returns to step ST11 and the exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{#. 7} , 28 Monitor _{# 8} for necessity.

On the other hand, in the exhaust pressure control means operating region (that is, the low / medium speed rotation region), the electronic control unit 29 determines the corresponding blowdown gas generating cylinder # 4 based on the engine speed and load at that time. , # 5, # 7 and # 8, the valve opening degree of the exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} and 28 _{# 8} is obtained from the map data (step ST12).

Thereafter, the electronic control unit 29 controls the exhaust pressure control means 28 _{# 4} , 28 _{# 5 for} the corresponding blowdown gas generating cylinders # 4, # 5, # 7, # 8 so that the obtained valve opening is obtained. , 28 _{# 7} and 28 _{# 8} are controlled (step ST13).

As a result, the exhaust passages 23 _{# 4} , 23 _{# 5} , 23 _{# 7} , and 23 _{# 8} relating to the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 to be controlled are throttled, and the wavy line in FIG. As shown in FIG.

For this reason, the internal EGR amount of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 is larger than that when the exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} , and 28 _{# 8} are fully opened. While the pressure wave of the blowdown gas is attenuated and the arrival time of the positive pressure wave to the other cylinder can be delayed, the blowdown gas inflow cylinder in which the internal EGR amount increases due to the influence of the blowdown gas The exhaust gas exhaust amount at # 6, # 3, # 1, and # 2 increases, and the variation in the internal EGR amount between the respective cylinders becomes small (or the same).

FIG. 9 is a diagram showing the pressure waveforms of the exhaust pulsation and the intake pulsation during a valve overlap period of a certain cylinder. The exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} , 28 _{# 8} It is a figure shown about the difference in the pressure waveform of exhaust pulsation at the time of full opening and operation.

  Thereafter, the electronic control unit 29 returns to step ST11 and repeats the same operation.

Thus, by providing the exhaust pressure control means 28 _{# 4} , 28 _{# 5} , 28 _{# 7} , 28 _{# 8} in the blowdown gas generating cylinders # 4, # 5, # 7, # 8, respectively, Since the variation in the internal EGR amount between the cylinders can be reduced (or made the same), the variation in the charging efficiency (air-fuel ratio) of the intake air between the cylinders becomes small (or uniform), and thereby the shaft Torque can be improved. Further, the valve overlap period is expanded in such a state that the variation in the internal EGR amount between the cylinders is small (or a uniform state), and further, the state in which the variation in the intake air charging efficiency (air-fuel ratio) is small (or a uniform state). Therefore, the internal EGR amount can be increased by extending the valve overlap period, and the amount of HC and NOx emissions can be reduced and the fuel consumption rate can be reduced.

  Next, a fourth embodiment of the internal combustion engine according to the present invention will be described with reference to FIG. Here, reference numeral 31 in FIG. 10 indicates the internal combustion engine of the fourth embodiment.

The internal combustion engine 31 of the fourth embodiment has a cylinder block 31a in which eight cylinders # 1 to # 8 are arranged in the left and right banks and two cylinder heads in the same positional relationship as the internal combustion engine 11 of the second embodiment. This is a V-type 8-cylinder internal combustion engine that includes 31b _LH and 31b _RH , and in which each cylinder # 1 to # 8 is ignited in the same ignition sequence.

Also in the fourth embodiment, as shown in FIG. 10, the intake manifold 32 is disposed between the left and right banks, while the exhaust path including the exhaust manifolds 33 _LH and 33 _{RH is provided} outside the engine of each bank. Is placed.

Here, the intake manifold 32 of the fourth embodiment includes first to eighth intake passages 32 _{# 1 to} 32 _{# 8} similar to the intake manifold 12 of the second embodiment, and the respective intake passages 32 are provided. Air in which the amount of intake is adjusted by the throttle valve 32a shown in FIG. 10 is guided to each cylinder # 1 to # 8 via _{# 1 to} 32 _{# 8} .

In the exhaust path of the fourth embodiment, the exhaust manifold 33 _LH , the first and second catalyst devices 34 _LH and 35 _LH and the first and second exhaust pipes 36 _LH and 37 _LH are provided on the left bank side. Further, an exhaust manifold 33 _RH , first and second catalyst devices 34 _RH , 35 _RH and first and second exhaust pipes 36 _RH , 37 _RH are provided on the right bank side. Each of the first exhaust pipes 36 _LH and 36 _RH is assembled in one path, and one catalyst device is arranged in place of the two second catalyst devices 35 _LH and 35 _RH on the downstream side of the gathered portion. May be.

As the exhaust manifolds 33 _LH and 33 _RH of the fourth embodiment, the same 4-2-1 type as in the second embodiment is used. That is, in the left-bank, in the first and fourth exhaust passage 33 _# 1, ₃₃ # 3, 33 _# 5, 33 manifolds 33a ₁ of the _{# 7} and the first from the 3, 33b _1, 33c ₁ An exhaust manifold 33 _LH is configured, and a first catalyst device 34 _LH is provided at the downstream end of the third collecting passage 33 c ₁ . On the other hand, in the right-bank, in the first and fourth exhaust passage 33 _# 2, 33 _# 4, 33 _# 6, 33 sets in a _{# 8} in the first third passage 33a _2, 33b _2, 33c ₂ An exhaust manifold 33 _RH is configured, and a first catalyst device 34 _RH is provided at the downstream end of the third collecting passage 33 c ₂ .

  Here, in the fourth embodiment, the blowdown gas generating cylinder exhaust pressure adjusting means similar to that in the third embodiment is provided.

Specifically, the blow-down gas generating cylinder exhaust pressure adjusting means on the left bank side of the fourth embodiment is similar to that of the third embodiment in the second collecting passage 33b ₁ of the exhaust manifold 33 _LH as shown in FIG. Atmospheric pressure control means 38 _{# 57} is provided.

As a result, the exhaust gas flow rates in the exhaust passages 33 _{# 5} and 33 _{# 7} relating to the blowdown gas generating cylinders # 5 and # 7 in the left bank can be adjusted in accordance with the valve opening degree. Since the exhaust pressure of the gas generating cylinders # 5 and # 7 can be variably controlled, the internal EGR amount increases due to the blowdown gas generating cylinders # 5 and # 7 and the respective blowdown gas cylinders # 3. , # 1 can be reduced (preferably the same) in the internal EGR amount.

On the other hand, as the blowdown gas generating cylinder exhaust pressure regulation means the right bank side, as shown in FIG. 10, provided exhaust pressure control means 38 # ₄₈ similar to the second collecting passage 33b ₂ of _RH exhaust manifold 33.

As a result, the exhaust gas flow rates of the exhaust passages 33 _{# 4} and 33 _{# 8 associated} with the blowdown gas generating cylinders # 4 and # 8 in the right bank can be adjusted according to the valve opening degree. Since the exhaust pressure of the gas generating cylinders # 4 and # 8 can be variably controlled, the blowdown gas whose internal EGR amount increases due to the influence of the blowdown gas generating cylinders # 4 and # 8 and their respective blowdown gases. Variations in the internal EGR amount between the inflow cylinders # 6 and # 2 can be reduced (preferably the same).

Here, the opening / closing operations of the respective exhaust pressure control means 38 _{# 57} and 38 _{# 48} are controlled by an electronic control unit (ECU) 39 shown in FIG. For this reason, even in the fourth embodiment, the valve opening degree corresponding to the engine speed and the load is obtained through experiments, simulations, and the like, and the corresponding relationship is prepared in advance as map data. Then, the electronic control unit 39 obtains the valve opening from the map data based on the engine speed and the load, and blowdown gas generating cylinders # 4, # 5, # 7, # 8 so as to be the valve opening. The exhaust pressure control means 38 _{# 48} , 38 _{# 57} , 38 _{# 57} , 38 _{# 48 according} to the above are controlled.

Similarly to the third embodiment, the electronic control unit 39 determines whether or not the exhaust pressure control means 38 _{# 57} and 38 _{# 48} need to be operated depending on whether or not the exhaust pressure control means is operating.

  The operation will be described below with reference to the flowchart of FIG.

  As in the third embodiment, the electronic control unit 39 according to the fourth embodiment determines whether or not the exhaust pressure control means is operating based on the engine speed information (step ST11). As a result, the exhaust pressure control means is determined. If it is not the operation region (that is, if it is a high-speed rotation region), the process returns to step ST11.

On the other hand, in the exhaust pressure control means operating region (that is, the low / medium speed rotation region), the electronic control unit 39 determines the corresponding blowdown gas generating cylinder # 4 based on the engine speed and load at that time. , # 5, # 7, # 8, the valve opening degree of the exhaust pressure control means 38 _{# 48} , 38 _{# 57} is obtained from the map data (step ST12).

Thereafter, the electronic control unit 39 adjusts the exhaust pressure control means 38 _{# 48} , 38 _{# 57} related to the blowdown gas generating cylinders # 4, # 5, # 7, # 8 so that the obtained valve opening is obtained. Is controlled (step ST13).

  As a result, as in the third embodiment, the exhaust pressure of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 to be controlled increases, and the amount of internal EGR increases due to the influence of the blowdown gas. Variations in the internal EGR amount between the blowdown gas inflow cylinders # 6, # 3, # 1, and # 2 can be reduced (preferably the same).

  Thereafter, the electronic control unit 39 returns to step ST11 and repeats the same operation.

  As described above, even in the fourth embodiment, the variation in the internal EGR amount between the respective cylinders described above becomes small (or becomes the same), so that the intake air charging efficiency (air-fuel ratio) between the cylinders is reduced. The variation is small (or uniform), which can improve the shaft torque. Further, the valve overlap period is expanded in such a state that the variation in the internal EGR amount between the cylinders is small (or a uniform state), and further, the state in which the variation in the intake air charging efficiency (air-fuel ratio) is small (or a uniform state). Therefore, the internal EGR amount can be increased by extending the valve overlap period, and the amount of HC and NOx emissions can be reduced and the fuel consumption rate can be reduced.

  Next, a fifth embodiment of the internal combustion engine according to the present invention will be described with reference to FIG. Here, reference numeral 41 in FIG. 11 shows the internal combustion engine of the fifth embodiment.

The internal combustion engine 41 of the fifth embodiment has a cylinder block 41a in which eight cylinders # 1 to # 8 are arranged in left and right banks and two cylinder heads in the same positional relationship as the internal combustion engine 11 of the second embodiment. This is a V-type 8-cylinder internal combustion engine that includes 41b _LH and 41b _RH , and in which each cylinder # 1 to # 8 is ignited in the same firing order.

Also in the fifth embodiment, as shown in FIG. 11, the intake manifolds 42 are disposed between the left and right banks, while the exhaust paths including the exhaust manifolds 43 _LH and 43 _RH are provided outside the engines of the respective banks. Is placed.

Here, the intake manifold 42 of the fifth embodiment includes first to eighth intake passages 42 _{# 1 to} 42 _{# 8} similar to the intake manifold 12 of the second embodiment, and the respective intake passages 42. Air whose intake amount is adjusted by the throttle valve 42a shown in FIG. 11 is guided to the cylinders # 1 to # 8 via _{# 1 to} 42 _{# 8} .

As for the exhaust path of the fifth embodiment, the exhaust manifold 43 _LH and the first and second catalytic devices 44 _LH and 45 _LH are provided on the left bank side, and further, after passing through the second catalytic device 45 _LH . A first exhaust pipe 46 _LH into which exhaust gas flows is provided. On the other hand, on the right bank side, an exhaust manifold 43 _RH and first and second catalytic devices 44 _RH and 45 _RH are provided, and further, a first exhaust into which exhaust gas after passing through the second catalytic device 45 _RH flows. A tube 46 _RH is provided.

Here, as the exhaust manifolds 43 _LH and 43 _RH of the fifth embodiment, the same 4-2-1 type as in the second embodiment is used. That is, on the left bank side, the first to fourth exhaust passages 43 _{# 1} , 43 _{# 3} , 43 _{# 5} , 43 _{# 7} and the first to third collective passages 43a ₁ , 43b ₁ , 43c ₁ An exhaust manifold 43 _LH is configured, and a first catalyst device 44 _LH is provided at the downstream end of the third collecting passage 43 c ₁ . On the other hand, in the right-bank, in the first and fourth exhaust passage 43 _# 2, 43 _# 4, 43 _# 6, 43 sets in a _{# 8} in the first third passage 43a _2, 43 b _2, 43c _{2 RH} exhaust manifold 43 is configured, _RH first catalyzer 44 is provided in the downstream end of the third collecting passage 43c _2.

  By the way, as described in the first embodiment, even in the V-type eight-cylinder internal combustion engine 41 of the fifth embodiment, if the valve overlap period is set, the first cylinder # 1, the third cylinder # 3, and the sixth cylinder When the cylinder # 6 and the second cylinder # 2 are in the valve overlap period, due to the influence of the blowdown gas of the seventh cylinder # 7, fifth cylinder # 5, fourth cylinder # 4 and eighth cylinder # 8, respectively. Exhaust interference can occur between the cylinders.

  Therefore, also in the fifth embodiment, there is provided blowdown gas generation cylinder exhaust pressure adjusting means for increasing the exhaust pressure of the blowdown gas generation cylinders # 4, # 5, # 7, and # 8.

Here, in the internal combustion engine 41 of the fifth embodiment, two catalyst devices 44 _LH , 45 _LH , 44 _RH , 45 _RH are disposed in each of the left and right banks, and each of the catalyst devices 44 _LH , 45 is provided. _LH , 44 _RH , and 45 _RH serve as exhaust gas passage resistance. For this reason, in the fifth embodiment, the first catalytic devices 44 _LH and 44 _RH on the upstream side are used as blowdown gas generating cylinder exhaust pressure adjusting means of the respective banks.

Specifically, in the fifth embodiment, the first catalyst device 44 _{LH in} the left bank is disposed on the second collecting passage 43b ₁ of the exhaust manifold 43 _LH , while the first catalyst device 44 _{RH in} the right bank is _installed . placed over the exhaust manifold 43 _RH second manifolds 43 b ₂ constituting the blowdown gas generating cylinder exhaust pressure adjusting means of the respective bank.

  As a result, the exhaust pressure of the above-described blowdown gas generating cylinders # 4, # 5, # 7, and # 8 is increased, and the internal EGR amount is increased. On the other hand, the pressure wave of the blowdown gas is attenuated and the positive pressure is increased. Since the arrival time of the pressure wave to the other cylinder can be delayed, the amount of exhaust gas discharged in the blowdown gas inflow cylinders # 6, # 3, # 1, and # 2 where the internal EGR amount increases due to the effect of the blowdown gas is To increase.

  For this reason, the variation in the internal EGR amount among the respective cylinders is reduced, so that the variation in the charging efficiency (air-fuel ratio) of the intake air is also reduced, thereby improving the shaft torque. Furthermore, such a state in which the variation in the internal EGR amount between the cylinders is small, and further, a state in which the variation in the intake air charging efficiency (air-fuel ratio) is small can be maintained even if the valve overlap period is expanded. By increasing the valve overlap period, the amount of internal EGR can be increased, and the amount of HC and NOx emissions can be reduced and the fuel consumption rate can be reduced.

Here, as described in the fifth embodiment, the first catalyst devices 44 _LH and 44 _RH can be arranged on the second collecting passages 43b ₁ and 43b ₂ , respectively. In order to make it more effective, internal EGR is caused by the influence of blowdown gas generating cylinders # 4, # 5, # 7, and # 8 and their respective blowdown gases by the first catalyst devices 44 _LH and 44 _RH . It is preferable that the internal EGR amount between the blowdown gas inflow cylinders # 6, # 3, # 1, and # 2 that increase the amount be uniform.

That is, the first catalyst devices 44 _LH and 44 _RH are set to the exhaust pressures of the blowdown gas generating cylinders # 4, # 5, # 7, and # 8 that can make the internal EGR amount uniform between the respective cylinders. Set the passage resistance to.

  As a result, the internal EGR amount between the cylinders is made uniform, so that the variation in intake air charging efficiency (air-fuel ratio) becomes uniform, and the shaft torque can be further improved. Further, since the uniform state of the internal EGR amount between the cylinders and the uniform state of the intake air charging efficiency (air-fuel ratio) can be maintained even if the valve overlap period is expanded, the valve overlap period is further increased. By increasing the internal EGR amount due to the expansion of the valve overlap period, it is possible to further reduce HC and NOx emissions and further reduce the fuel consumption rate.

In the fifth embodiment, the first catalyst devices 44 _LH and 44 _RH are used as the blowdown gas generating cylinder exhaust pressure adjusting means of the respective banks. However, the present invention is not limited to this.

For example, the pipe diameters of the respective second collecting passages 43b ₁ and 43b ₂ are made smaller than the pipe diameters of the exhaust passages 43 _{# 5} , 43 _{# 7} , 43 _{# 4} and 43 _{# 8} , or their respective second collecting passages. The blow-down gas generating cylinder exhaust pressure adjusting means may be configured by providing a throttle at 43b ₁ and 43b ₂ . Also, a so-called variable valve lift amount mechanism capable of varying the lift amount of the exhaust valve is provided in at least the blowdown gas generating cylinders # 4, # 5, # 7, and # 8, and the blowdown gas generating cylinders # 4, # 5, and so on. The lift amount of the exhaust valves of # 7 and # 8 is made smaller than the blowdown gas inflow cylinders # 6, # 3, # 1, and # 2 where the internal EGR amount increases due to the influence of the respective blowdown gases. Blowdown gas generating cylinder exhaust pressure adjusting means may be configured.

  In each of the first to fifth embodiments, the first cylinder # 1 → 8th cylinder # 8 → 7th cylinder # 7 → 3rd cylinder # 3 → 6th cylinder # 6 → 5th cylinder # 5 → 4th Although the case where the order of ignition of the cylinder # 4 → second cylinder # 2 is set as an example, the present invention can be applied to other ignition orders.

  For example, the firing order is 1st cylinder # 1 → 8th cylinder # 8 → 4th cylinder # 4 → 3rd cylinder # 3 → 6th cylinder # 6 → 5th cylinder # 5 → 7th cylinder # 7 → 2nd In the case of cylinder # 2, if the valve overlap period is set in this ignition order, the first cylinder # 1, the fifth cylinder # 5, the sixth cylinder # 6, and the eighth cylinder # 8 become blowdown gas generating cylinders. The seventh cylinder # 7, the third cylinder # 3, the fourth cylinder # 4 and the second cylinder # 2 are affected by the blowdown gas.

  Further, the ignition order is 1st cylinder # 1 → 2nd cylinder # 2 → 7th cylinder # 7 → 8th cylinder # 8 → 4th cylinder # 4 → 5th cylinder # 5 → 6th cylinder # 6 → 3rd cylinder In the case of # 3, if the valve overlap period is set in this ignition order, the third cylinder # 3, sixth cylinder # 6, seventh cylinder # 7 and eighth cylinder # 8 become blowdown gas generating cylinders. The fifth cylinder # 5, the fourth cylinder # 4, the first cylinder # 1, and the second cylinder # 2 are affected by the blowdown gas.

  For this reason, the present invention illustrated in each of the first to fifth embodiments is filled with intake air between a blowdown gas generating cylinder corresponding to the ignition order and a cylinder whose internal EGR amount increases due to the blowdown gas. The efficiency (air-fuel ratio) is configured to be uniform.

  As described above, the internal combustion engine according to the present invention has uniform intake air charging efficiency (air-fuel ratio) between a cylinder that generates blowdown gas and a cylinder that has an increased internal EGR amount due to the blowdown gas. This is useful as a technology for achieving the above.

1 is a diagram illustrating a configuration of a first embodiment of an internal combustion engine according to the present invention. FIG. FIG. 4 is a diagram showing an example of valve opening / closing timings of an intake valve and an exhaust valve in a V-type 8-cylinder internal combustion engine, and a blow-down gas generation cylinder when a valve overlap period is set and a blow affected by the blow-down gas It is a figure which shows the correspondence with a down gas inflow cylinder. FIG. 3 is a diagram showing an example of valve opening / closing timings of an intake valve and an exhaust valve in a V-type 8-cylinder internal combustion engine, and a blowdown gas generation cylinder when the valve overlap period is expanded by means such as a variable valve timing mechanism and the like It is a figure which shows the correspondence with the blowdown gas inflow cylinder which receives the influence of blowdown gas. It is explanatory drawing explaining the intake pressure control means action | operation area | region of Example 1. FIG. 3 is a flowchart illustrating a control operation of an intake pressure control unit according to the first embodiment. It is a figure which shows the pressure waveform of the exhaust pulsation of the cylinder which is in a valve overlap period, and an intake pulsation, Comprising: It is a figure which shows the difference in the pressure waveform of the intake pulsation when the intake pressure control means is fully opened and during operation. It is a figure which shows the structure of Example 2 of the internal combustion engine which concerns on this invention. It is a figure which shows the structure of Example 3 of the internal combustion engine which concerns on this invention. 10 is a flowchart illustrating a control operation of an exhaust pressure control unit according to a third embodiment. It is a figure which shows the pressure waveform of the exhaust pulsation and the intake pulsation of the cylinder which is in a valve overlap period, Comprising: It is a figure which shows the difference in the pressure waveform of an exhaust pulsation when the exhaust pressure control means is fully opened and at the time of operation. It is a figure which shows the structure of Example 4 of the internal combustion engine which concerns on this invention. It is a figure which shows the structure of Example 5 of the internal combustion engine which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake manifold 2 _# 1-2 _{# 8} 1st-8th intake passage 8 _{# 4} , 8 _{# 5} , 8 _{# 7} , 8 _{# 8} Intake pressure control means (flow-path on-off valve)
9 Electronic control unit (ECU)
DESCRIPTION OF SYMBOLS 11 Internal combustion engine 12 Intake manifold 12 _# 1-12 _{# 8} 1st-8th intake passage 18 _{# 4} , 18 _{# 5} , 18 _{# 7} , 18 _{# 8} Intake pressure control means (flow-path on-off valve)
19 Electronic control unit (ECU)
21 Internal combustion engine 23 _LH , 23 _RH Exhaust manifold 23 _{# 1} to 23 _{# 8} Exhaust passage 28 _{# 4} , 28 _{# 5} , 28 _{# 7} , 28 _{# 8} Exhaust pressure control means (blowdown gas generation cylinder exhaust pressure adjustment means)
29 Electronic control unit (ECU)
31 Internal combustion engine 33 _LH , 33 _RH Exhaust manifold 33 _{# 1 to} 33 _{# 8} Exhaust passage 33 _{b 1} , 33 _b 2 Second collecting passage 38 _{# 57} , 38 _{# 48} Exhaust pressure control means (blowdown gas generation cylinder exhaust pressure adjustment means)
39 Electronic control unit (ECU)
41 Internal combustion engine 43 _LH , 43 _RH Exhaust manifold 43 _{# 1} to 43 _{# 8} Exhaust passage 43 b ₁ , 43 b ₂ Second collecting passage 44 _LH , 44 _RH first catalyst device (blowdown gas generating cylinder exhaust pressure adjusting means)
# 1- # 8 1st cylinder-8th cylinder

Claims (1)

In an internal combustion engine that has two banks and each cylinder on the same bank explodes at unequal intervals,
The exhaust passage of the first cylinder whose valve overlap period does not overlap with the opening timing of the exhaust valves of the other cylinders can be opened and closed, and the exhaust pressure of the first cylinder is increased by reducing the valve opening. A flow path opening / closing valve capable of
By reducing the valve opening degree of the flow path opening / closing valve provided only on the exhaust passage of the first cylinder, the internal EGR amount in the first cylinder is reduced from when the valve opening degree of the flow path opening / closing valve is fully open. And the exhaust amount of exhaust gas in the second cylinder where the valve overlap period overlaps with the opening timing of the exhaust valves of the other cylinders is increased to increase the internal EGR between the first cylinder and the second cylinder. Control means for reducing variation in the amount or making the internal EGR amount uniform between the cylinders;
An internal combustion engine comprising:

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