JP2006112277A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of accurately detecting dispersion of intake air quantity among cylinders with a simple detection structure. <P>SOLUTION: This internal combustion engine 10 includes two banks (A bank and B bank) composed of only cylinders in which lift operating angle of an intake valve does not overlap each other and intake air collecting passages 15a/15b having intake air branch passages 17a/17b individually connected to each cylinder #1-#4/#5-#8 collected and connected to are provided for each bank. Intake air pressure sensor 52a/52b detecting intake air pressure are provided in surge tanks 16a/16b provided in the intake air collecting passages 15a/15b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine having a plurality of cylinders, and more particularly to an internal combustion engine having a detection device that detects variations in the intake air amount among the cylinders.

  In a multi-cylinder internal combustion engine, the intake air amount of each cylinder may vary due to individual differences in the intake system members and changes over time. When the variation in the intake air amount becomes large, various inconveniences such as, for example, fluctuations in the engine rotation speed are caused. In order to avoid such inconvenience, various internal combustion engines provided with a device for detecting variations in intake air amount have been proposed.

  As an internal combustion engine having such a detection device, for example, the one described in Patent Document 1 is known. In this internal combustion engine, an in-cylinder pressure sensor for detecting the pressure in the cylinder is provided in each of the plurality of cylinders. Then, the intake air amount is obtained for each cylinder based on the in-cylinder pressure detected by the corresponding in-cylinder pressure sensor, and the intake air amount variation is detected.

Moreover, the thing of patent document 2 is also known as an internal combustion engine which has the said detection apparatus. In this internal combustion engine, an intake pressure sensor for detecting the pressure of intake air is provided in a portion (specifically, a surge tank) where the branch passages extending from the plurality of cylinders are gathered in the intake passage. . The intake pressure sensor detects the intake pressure at the timing of air intake in each cylinder, and the intake air amount is obtained for each cylinder from the intake pressure. As a result, the intake air amount variation between the cylinders is detected.
Japanese Patent Publication No. 7-3204 JP 2001-234798 A

  By the way, in the internal combustion engine described in Patent Document 1, the intake air amount of each cylinder can be obtained with high accuracy, and the intake air amount variation between the cylinders can be detected with high accuracy. it can. However, since it is necessary to provide in-cylinder pressure sensors for all the cylinders, this leads to a complicated configuration, and there is still room for improvement in this respect.

  On the other hand, in the internal combustion engine described in Patent Document 2, it is possible to detect the intake air amount for all the cylinders using only one intake pressure sensor for detecting the intake pressure in the surge tank. . However, in the surge tank of the internal combustion engine, intake pressure fluctuations due to air suction in each cylinder interfere with each other. With the described internal combustion engine, it is difficult to obtain high detection accuracy.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an internal combustion engine capable of accurately detecting variations in the intake air amount between cylinders with a simple detection structure.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
First, the invention according to claim 1 has a plurality of cylinder groups composed only of cylinders that can be in a state in which the valve opening periods of the intake valves do not overlap each other, and each cylinder group is provided for each cylinder. The gist of the present invention is to include a collecting passage in which branch passages connected separately are connected and a detection unit that detects an intake pressure of the collecting passage.

  According to this configuration, for each cylinder group, the suction of the collecting passage caused by the opening and closing of the intake valve of the predetermined cylinder is performed in a state where the influence of the pressure fluctuation due to the opening of the intake valve of the other cylinder is extremely small. Pressure fluctuation can be detected. Therefore, by comparing the magnitude of the intake pressure fluctuation for each cylinder, it is possible to accurately detect the variation in the intake air amount for each cylinder. In addition, unlike the case where a detection unit for detecting the intake pressure is provided for each cylinder, such a variation in intake air amount can be detected with high accuracy with a simple detection structure.

The internal combustion engine includes the internal combustion engines described in the following (A) and (B).
(A) An internal combustion engine in which the valve opening periods are set in advance so that the valve opening periods of the intake valves of the cylinders constituting the same cylinder group do not overlap in any operating region.
(B) An internal combustion engine in which the valve opening periods of the intake valves of the respective cylinders constituting the same cylinder group are switched between an overlapping state and a non-overlapping state according to the engine operating state.

  Further, the gist of the invention according to claim 2 is that, in the internal combustion engine according to claim 1, the cylinder group is constituted only by cylinders in which the valve opening periods of the exhaust valves do not overlap each other. .

  According to this configuration, for each cylinder group, detection of intake pressure fluctuations associated with the opening / closing valves of the predetermined cylinders while avoiding as much as possible the adverse effects of exhaust pressure fluctuations associated with the opening / closing valves of the exhaust valves of the other cylinders. Will be able to. Therefore, the variation in the intake air amount for each cylinder can be detected more accurately.

  According to a third aspect of the present invention, in the internal combustion engine of the first or second aspect, the valve opening period is set so that the lift amount becomes smaller as the valve opening period of the intake valve is set shorter. The gist is to further include a change mechanism that can be changed.

  In an internal combustion engine equipped with a mechanism for changing the intake valve opening period so that the lift amount becomes smaller as the intake valve opening period is set shorter, the internal combustion engine has an intake The shorter the valve opening period is set and the smaller the lift amount, the narrower the gap through which the intake air passes when the valve is opened. Also, during low load operation, such as during idle operation where the lift amount is set to be small, the greater the variation in the intake air amount of each cylinder, the more adverse effects such as increased fluctuations in engine rotation speed caused by it. It will be big. That is, in such an internal combustion engine, it can be said that the internal combustion engine is easily affected by the deposit adhesion to the intake valve or the like or the variation in the changing operation of the changing mechanism.

  In this regard, according to the above configuration, it is possible to accurately detect the intake air amount variation of the internal combustion engine including such a change mechanism. Further, in the case of the same configuration, it is possible to determine whether or not the operation of the change mechanism is normal by detecting the variation in the intake air amount among the cylinders. That is, when the opening period of the intake valve of the specific cylinder is different from the target period, the variation in intake air amount becomes large, and based on this, it is determined whether or not the changing mechanism is operating normally. be able to.

  According to a fourth aspect of the present invention, in the internal combustion engine according to the first or second aspect, a state in which the valve opening periods of the intake valves of the respective cylinders constituting the same cylinder group overlap with each other does not overlap. The change mechanism is further provided, and the detection unit performs the detection of the intake pressure when the change mechanism is changed to the non-overlapping state.

  According to this configuration, when the valve opening periods of the intake valves of the cylinders constituting the same cylinder group do not overlap through the operation of the change mechanism, the variation occurring in the intake air amount of the cylinders is detected. Therefore, accurate detection can be performed. Furthermore, in the case of the same configuration, it is possible to determine whether or not the operation of the change mechanism is normal by detecting the variation in the intake air amount between the cylinders. That is, when the opening period of the intake valve of the specific cylinder is different from the target period, the variation in intake air amount becomes large, and based on this, it is determined whether or not the changing mechanism is operating normally. be able to.

  In addition, as a change mechanism in the configuration, as in the configuration of claim 3, the valve opening period can be changed so that the lift amount becomes smaller as the valve opening period of the intake valve is set shorter. As described above, it is possible to accurately detect the intake air amount variation in an internal combustion engine that is easily affected by the deposit adhesion to the intake valve or the like and the change mechanism change operation variation as described above. Will be able to.

  In order to realize the configuration according to any one of claims 1 to 4 in an internal combustion engine having two banks, such as an internal combustion engine having a V-type or horizontally opposed cylinder arrangement, for example. As in the configuration described in Item 5, it is desirable to set a cylinder group for each bank and set an ignition order so that ignition is performed alternately for each bank. By comprising in this way, complication of the arrangement structure of a branch passage and a gathering passage can be suppressed as much as possible.

  Further, in the configuration according to claim 5, by providing, for each bank, a collective passage to which the branch passages of the exhaust system separately connected to each cylinder are connected. When embodying the configuration, it is possible to suppress as much as possible the complexity of the arrangement structure of the branch passages and the collecting passages.

Hereinafter, an embodiment embodying an internal combustion engine according to the present invention will be described.
The internal combustion engine according to the present embodiment is a V-type 8-cylinder internal combustion engine that includes an A bank and a B bank, and each bank includes four cylinders.

First, a schematic configuration of the internal combustion engine according to the present embodiment will be described.
Since the basic structure of each bank of the internal combustion engine is the same, only the basic structure of the A bank will be described here, and the description of the basic structure of the B bank will be omitted. Further, in the following description, the same components in each bank are given the same numbers as the reference numerals, and in order to distinguish them, “a” is added to the end of the components in the A bank, “B” is added to the end of B bank components. In addition, only the number is attached | subjected as a code | symbol about the component which does not need to distinguish for every bank.

FIG. 1 shows a schematic configuration of the A bank of the internal combustion engine according to the present embodiment.
As shown in FIG. 1, a throttle valve 12 is provided in the intake passage 11 of the internal combustion engine 10. A throttle motor 13 is connected to the throttle valve 12. Then, the opening degree of the throttle valve 12 (throttle opening degree TA) is adjusted through the drive control of the throttle motor 13, thereby adjusting the amount of air taken into each combustion chamber 14 through the intake passage 11.

  The intake passage 11 is branched into two passages on the downstream side of the throttle valve 12, one of which (the intake collective passage 15a) is connected to the A bank, and the other (the intake collective passage 15b) is connected to the B bank. Has been. A surge tank 16a is provided in the middle of the intake air collecting passage 15a. The intake manifold passage 15a is further branched into four intake branch passages 17a on the downstream side of the surge tank 16a. These intake branch passages 17a are connected to the respective cylinders # 1 to # 4 (only one cylinder is shown in the drawing). Each intake branch passage 17a is provided with a fuel injection valve 18 respectively. The fuel injection valve 18 injects fuel into the intake branch passage 17a.

  In each combustion chamber 14 of the internal combustion engine 10, ignition by an ignition plug 19 is performed on an air-fuel mixture composed of intake air and injected fuel. By this ignition operation, the air-fuel mixture burns, the piston 20 reciprocates, and the crankshaft 21 rotates. The combusted air-fuel mixture is sent as exhaust from each combustion chamber 14 to the exhaust passage 22 (specifically, the exhaust branch passage 23a), and an exhaust purification catalyst provided in the exhaust passage 22 (specifically, the exhaust collective passage 24a). After being purified through 25a, it is discharged to the outside.

  In the internal combustion engine 10, the intake branch passage 17a and the combustion chamber 14 are communicated and cut off by the opening and closing operation of the intake valve 30a, and the combustion chamber 14 and the exhaust branch passage 23a are communicated and opened by the opening and closing operation of the exhaust valve 32a. Blocked. Further, the intake valve 30a opens and closes with the rotation of the intake camshaft 34a to which the rotation of the crankshaft 21 is transmitted, and the exhaust valve 32a similarly rotates with the rotation of the exhaust camshaft 36a to which the rotation of the crankshaft 21 is transmitted. Open and close.

  An operating angle changing mechanism 38a is provided between the intake camshaft 34a and the intake valve 30a. The operating angle changing mechanism 38a variably sets the valve opening period (lift operating angle) of the intake valve 30a according to engine operating conditions, and operates through drive control of an actuator 40a such as an electric motor. FIG. 2 shows how the lift operating angle of the intake valve 30a is changed by the operation of the operating angle changing mechanism 38a. As can be seen from FIG. 2, by the operation of the operating angle changing mechanism 38a, the lift operating angle of the intake valve 30a changes in synchronization with the lift amount. For example, the lift amount decreases as the lift operating angle decreases. A reduction in the lift operating angle means that the opening timing and closing timing of the intake valve 30a approach each other, and means that the opening period of the intake valve 30a is shortened.

  In the present embodiment, the amount of intake air is adjusted through cooperative control of the opening degree control (throttle control) of the throttle valve 12 (FIG. 1) and the operation control of the operating angle changing mechanism 38a (lift operating angle variable control). Done. The intake air amount increases as the throttle opening TA increases and as the lift operating angle of the intake valve 30a increases. Therefore, in the above cooperative control, when the lift operating angle of the intake valve 30a is set large, the throttle opening degree TA is set relatively small, and conversely, when the lift operating angle is set small, the throttle opening degree TA is set. Throttle control and variable lift operation angle control are executed so as to set the pressure relatively large, and the intake air amount is adjusted to a desired amount. In this cooperative control, the lift operating angle and the throttle opening degree TA of the intake valve 30a are set larger as the engine load is larger.

  As described above, in the internal combustion engine 10, in addition to changing the throttle opening TA, the intake air amount is adjusted by changing the lift operating angle of the intake valve 30a. In this case, it is possible to operate the engine at a low output (low air amount) rather than reducing the intake air amount only by narrowing the throttle valve 12. This is due to the following reason.

  In the configuration in which the amount of intake air is adjusted by changing the lift operating angle, the degree of throttle by the throttle valve 12 is reduced, so that the pressure of intake air on the upstream side of the intake valve 30a increases. Therefore, when a predetermined amount of air is introduced into the combustion chamber 14, that is, when the final combustion chamber 14 pressure in the engine intake stroke becomes the same, the combustion chamber 14 pressure in the middle of the engine intake stroke becomes the throttle valve. This is because the configuration in which the lift operating angle is changed is higher than the configuration in which only 12 is reduced, and the pumping loss is reduced accordingly.

  In view of this point, in the cooperative control according to the present embodiment, the operating angle changing mechanism 38a is configured so that the lift operating angle becomes smaller than the configuration in which the intake air amount is reduced only by throttle the throttle valve 12. Is controlled. As a result, fuel efficiency is improved.

The internal combustion engine according to the present embodiment includes various sensors for detecting the operating state.
Examples of such various sensors include a crank sensor for detecting the rotation angle (crank angle) of the crankshaft 26, and a lift operating angle (more precisely, operating angle) of the intake valve 30a set by the operating angle changing mechanism 38a. An operating angle sensor is provided for detecting the operating amount of the changing mechanism 38a. In addition, an intake pressure sensor 52a for detecting the pressure (intake pressure) of the intake air in the surge tank 16a is also provided. In the present embodiment, the intake pressure sensor 52a (and the intake pressure sensor 52b) functions as a detection unit that detects the intake pressure in the collecting passage.

  The internal combustion engine 10 includes an electronic control device 50 configured to include, for example, a microcomputer. The electronic control device 50 takes in detection signals from various sensors and performs various calculations. Based on the calculation results, the throttle control, the lift working angle variable control, and the drive control of the fuel injection valve 18 (fuel injection control). And so on.

Next, schematic configurations of the intake system and the exhaust system of the internal combustion engine 10 will be described with reference to FIG.
In the present embodiment, the intake system and the exhaust system of the internal combustion engine 10 are configured as follows in order to accurately detect the intake air amount variation with a relatively simple detection structure.

  As shown in FIG. 3, in the internal combustion engine 10, the intake manifold passages 15a and 15b, the surge tanks 16a and 16b, the intake pressure sensors 52a and 52b in the intake system, and the exhaust collect passage in the exhaust system. 24a and 24b and exhaust purification catalysts 25a and 25b are provided separately for each bank.

  Further, in the internal combustion engine 10, the ignition order is set so that ignition is not performed continuously in the same bank, in other words, ignition is performed alternately in each bank. Specifically, as shown in the stroke diagram of the internal combustion engine 10 in FIG. 4, the ignition order is “cylinder # 5 (bank B) → cylinder # 1 (bank A) → cylinder # 6 (bank B) → cylinder. # 3 (A bank) → cylinder # 8 (B bank) → cylinder # 4 (A bank) → cylinder # 7 (B bank) → cylinder # 2 (A bank) ”. Thereby, each bank is comprised only by the cylinder which can be in the state which the lift action angle of mutual intake valve 30a, 30b does not overlap, respectively.

  Further, in the internal combustion engine 10, through the variable lift operation angle control, the lift operation angles of the plurality of intake valves 30a and 30b corresponding to the same bank are switched between the overlapping state and the non-overlapping state. It has become. Specifically, when the internal combustion engine 10 is in a high load operation, the lift operation angles of the plurality of intake valves 30a and 30b corresponding to the same bank are overlapped. For example, during a low load operation such as an idle operation, the lift operation angle is the same. Will not overlap. On the other hand, the plurality of exhaust valves 32a and 32b corresponding to the cylinders of the same bank are set in advance so that their lift operating angles do not overlap in any engine operating state.

  FIG. 5 shows the intake of the A bank during low load operation of the internal combustion engine 10 (specifically, when the lift operating angles of the plurality of intake valves 30a and 30b corresponding to the same bank are not overlapped). The graph shows (a) intake flow rate and (b) intake pressure transition in the system. FIG. 6 also shows the transition of (a) intake flow rate and (b) intake pressure in the intake system of the B bank during the low load operation of the internal combustion engine 10. 5 (a) and 6 (a), the solid line shows the transition of the air amounts Mca and Mcb taken into the cylinders from the surge tanks 16a and 16b, and the alternate long and short dash line shows the surge from the upstream side of the throttle valve 12. The transition of the air amounts Mta and Mtb flowing into the tanks 16a and 16b is shown.

  As shown in FIGS. 5 (a) and 6 (a), air amounts Mca and Mcb taken into the respective cylinders from the surge tanks 16a and 16b and flow into the surge tanks 16a and 16b from the upstream side of the throttle valve 12. Both the air quantities Mta and Mtb pulsate so as to increase once with the opening of the intake valves 30a and 30b in each cylinder and then decrease with the closing of the valves.

  Accordingly, as shown in FIGS. 5B and 6B, the intake pressure in the surge tanks 16a and 16b is also started as a result of opening the intake valves 30a and 30b in each cylinder. After pulsing, the air pulsates such that it rises due to the stop of air suction accompanying the closing of the intake valves 30a and 30b.

  In the present embodiment, the intake pressure fluctuation amounts (for example, “maximum value−minimum value”) associated with the opening / closing valves of the intake valves 30a and 30b are detected by the intake pressure sensors 52a and 52b, and the fluctuation amounts of the pressures are detected. By comparing, the intake air amount variation between the cylinders is detected.

  Note that, as a method for detecting such variation in intake air amount, a detection method based on the rotational fluctuation of the crankshaft 21, a detection method based on the exhaust air-fuel ratio, and the like are also conceivable. However, since these detection methods are affected by variations in the injection amounts of the fuel injection valves 18, it is difficult to ensure high detection accuracy. In this respect, since the detection method based on the variation amount of the intake pressure is not affected by the variation in the injection amount, it is possible to detect the variation in the intake air amount with relatively high accuracy.

  Here, if the lift operation angle of the intake valve overlaps, it is an influence on the intake pressure when the intake valve of the predetermined cylinder is opened, and the intake by the opening of the intake valve of the other cylinder that overlaps the intake valve. The effect of fluctuations in atmospheric pressure becomes extremely large. This also changes the pressure fluctuation amount, which causes a decrease in the accuracy in detecting the intake air amount based on the pressure fluctuation amount.

  Therefore, in the internal combustion engine 10 according to the present embodiment, the lift operating angles of the plurality of intake valves 30a and 30b corresponding to the same bank are changed to a state in which they do not overlap through the lift operating angle variable control. In this case, the intake pressure, and hence the fluctuation amount of the intake pressure, is detected. As a result, for each bank, the amount of fluctuation in intake pressure due to the opening and closing of the intake valves 30a, 30b of the predetermined cylinders under the condition that the influence of pressure fluctuations due to the opening of the intake valves 30a, 30b of the other cylinders is extremely small. Will be detected.

  Therefore, by comparing the variation amount of the intake pressure for each cylinder, it is possible to accurately detect the variation in the intake air amount for the cylinders. In addition, unlike the case where a detection unit for detecting the intake pressure is provided for each cylinder, such intake air amount variation has a relatively simple detection structure in which intake pressure sensors 52a and 52b are provided in the respective surge tanks 16a and 16b. Can be detected with high accuracy.

Further, in such a detection method based on the variation amount of the intake pressure, the variation in the intake air amount can be detected more accurately as the pulsation width of the intake pressure is larger.
FIG. 7 shows a comparative example A of the internal combustion engine 10 during operation of an internal combustion engine in which a surge tank common to all cylinders is provided and the lift operating angles of the intake valves are set to overlap. The graph shows (a) intake flow rate and (b) intake pressure transition in the intake system.

  In this embodiment, since the intake pressure is detected when the lift operating angles of the intake valves 30a corresponding to the same bank do not overlap, the pulsation width of the intake pressure (ΔPAa in FIG. 5, ΔPAb in FIG. 6). ) Is larger than the pulsation width of the intake pressure in the comparative example A (ΔPAi in FIG. 7). In the present embodiment, even when the pulsation width of the intake pressure is set to be large as described above, accurate detection of the intake air amount variation can be realized.

  On the other hand, during the operation of the internal combustion engine 10 (FIG. 3), the exhaust passage 22 is upstream of the exhaust purification catalysts 25a and 25b, that is, the exhaust branch passages 23a and 23b and the exhaust collecting passages 24a and 24b. The exhaust pressure in the interior also pulsates, similar to the intake pressure described above. Specifically, the exhaust valve 32a, 32b once rises with exhaust emission from the combustion chamber 14 due to the opening of the exhaust valves 32a, 32b, and then decreases with the stop of exhaust emission accompanying the closing of the exhaust valves 32a, 32b. It is pulsating.

  By the way, if the lift operating angle of each exhaust valve is set to overlap, it is an influence on the exhaust pressure when the exhaust valve of the predetermined cylinder is opened, and is due to the opening of the exhaust valve of the overlapping other cylinder. The influence on the exhaust pressure fluctuation becomes extremely large. This unnecessarily changes the amount of exhaust discharged from the predetermined cylinder to the exhaust passage and the amount of exhaust gas recirculated from the exhaust passage to the predetermined cylinder (so-called internal EGR amount). Since the relationship between the intake air amount and the intake air amount is changed, it becomes a factor that hinders improvement in detection accuracy of the intake air amount variation.

  On the other hand, in the internal combustion engine 10, the lift operating angles of the exhaust valves 32a and 32b corresponding to the respective cylinders in the same bank are set in advance so as not to overlap in any operating state. Therefore, each bank is associated with the opening / closing valves of the intake valves 30a, 30b of the predetermined cylinders in a situation where it is possible to avoid as much as possible the adverse effects due to the exhaust pressure fluctuations associated with the opening / closing valves of the exhaust valves 32a, 32b of the other cylinders. A fluctuation amount of the intake pressure is detected.

  On the other hand, in the internal combustion engine 10, the lift amount is set to be smaller as the lift operating angle of the intake valves 30a and 30b is set smaller through the operating angle changing mechanisms 38a and 38b. Therefore, as shown in FIG. 8, the relationship between the clearance through which the intake air passes (specifically, the clearance between the intake valve 30a and the valve seat S when the valve is opened) and the lift operating angle of the intake valve 30a is shown. As the lift working angle is set to be small and the lift amount is small, the same interval is narrowed.

  Further, as described above, in the cooperative control according to the present embodiment, the lift operating angle is smaller than that of the internal combustion engine (Comparative Example B) in which the intake air amount is reduced only by narrowing the throttle valve 12. Thus, the lift working angle variable control is executed.

  Therefore, as shown in FIG. 9, the intake valve 30a and its peripheral structure when the valve is opened are maintained in a comparatively large state in the comparative example B (FIG. 9 (b)). In the internal combustion engine 10 according to the present embodiment, for example, the gap is very small during low load operation such as during idling (FIG. 9A).

  The one-dot chain line in FIG. 8 indicates the relationship between the clearance and the lift operating angle of the intake valve 30a when the clearance changes due to individual differences in the operating angle changing mechanism 38a, deterioration over time, or deposit adhesion to the intake valve 30a. An example is shown.

  As is apparent from FIG. 8, the smaller the lift operating angle, the larger the ratio (change rate) of the gap change amount ΔCL to the entire gap. Therefore, in the internal combustion engine 10 in which the gap is set to be very small through the operation control of the operating angle changing mechanisms 38a and 38b, compared to the comparative example B, deposits are attached to the intake valves 30a and 30b. It can be said that the influence due to the above and the influence due to the variation in the variable operation of the working angle changing mechanisms 38a and 38b appear remarkably. Further, during low load operation of the internal combustion engine 10 such as during idle operation where the lift amount is set to be small as described above, the greater the variation in the intake air amount, the greater the adverse effects such as increased fluctuations in the engine rotational speed. Will also be big. According to the present embodiment, it is possible to accurately detect the intake air amount variation of the internal combustion engine 10 and to appropriately cope with this when the intake air amount variation becomes large. become.

  Further, according to the present embodiment, it is possible to determine whether or not the operation of the operating angle changing mechanisms 38a and 38b is normal through detection of variation in the intake air amount between the cylinders. That is, when the lift operating angle of the intake valve of the specific cylinder is different from the target lift operating angle, the variation of the intake air amount becomes large. Based on this, the operating angle changing mechanisms 38a and 38b operate normally. It can be determined whether or not.

As described above, according to the present embodiment, the effects described below can be obtained.
(1) Intake collecting passages 15a and 15b, surge tanks 16a and 16b, and intake pressure corresponding to each bank constituted only by cylinders in which the lift operating angles of the intake valves 30a and 30b can be non-overlapping. The sensors 52a and 52b are provided separately. Therefore, for each bank, the fluctuation amount of the intake pressure due to the opening and closing of the intake valves 30a, 30b of the predetermined cylinders under the condition that the influence of the pressure fluctuations due to the opening of the intake valves 30a, 30b of the other cylinders is extremely small. Can be detected. Therefore, by comparing the variation amount of the intake pressure for each cylinder, it is possible to accurately detect the variation in the intake air amount for each cylinder. In addition, unlike the case where a detection unit for detecting the intake pressure is provided for each cylinder, such intake air amount variation is provided with a relatively simple detection structure in which the intake tanks 52a and 52b are provided in the surge tanks 16a and 16b, respectively. Can be detected with high accuracy.

  (2) The lift operating angles of the exhaust valves 32a and 32b corresponding to the cylinders in the same bank are set so as not to overlap. Therefore, for each bank, the intake pressure fluctuations accompanying the opening / closing valves of the intake valves 30a, 30b of the predetermined cylinder are detected while avoiding as much as possible the adverse effects of the exhaust pressure fluctuations accompanying the opening / closing valves of the exhaust valves 32a, 32b of the other cylinders. As a result, the variation in the intake air amount can be detected more accurately.

  (3) In the internal combustion engine 10 in which the influence due to deposits on the intake valves 30a, 30b and the like and the influence due to the variation in the variable operation of the working angle changing mechanisms 38a, 38b appear remarkably, the variation in intake air amount is accurately detected. be able to.

  (4) When the lift operating angles of the plurality of intake valves 30a and 30b corresponding to the same bank are changed to a non-overlapping state through the operating angle changing mechanisms 38a and 38b, the fluctuation amount of the intake pressure is detected. Therefore, the intake air amount variation can be detected with high accuracy.

  (5) The internal combustion engine 10 has a V-type cylinder arrangement, and the ignition order is set so that the banks are alternately ignited. As a result, the intake manifold passages 15a and 15b, the surge tanks 16a and 16b, and the intake pressure sensors 52a and 52b correspond to a cylinder group composed of only cylinders that can be in a state where the valve opening periods of the intake valves do not overlap each other. Therefore, it is possible to suppress the complication of the arrangement structure as much as possible.

  Further, exhaust collecting passages 24a and 24b to which exhaust branch passages 23a and 23b connected to each cylinder are connected are provided for each bank. Therefore, when the exhaust collecting passages 24a and 24b are separately provided corresponding to the cylinder groups constituted only by the cylinders in which the lift operating angles of the exhaust valves 32a and 32b do not overlap, the exhaust branch passages 23a and 23b and the exhaust collecting passages are provided. This can be suppressed as much as possible even when the arrangement structure of the passages 24a and 24b is complicated.

The embodiment described above may be modified as follows.
In the above embodiment, in order to detect variations in the intake air amount, the intake pressure sensors 52a and 52b detect the amount of fluctuation in intake pressure associated with the opening / closing valves of the intake valves 30a and 30b. As the detected intake pressure fluctuation amount, the difference between the maximum value and the minimum value of the intake pressure (maximum value−minimum value), the ratio between the maximum value and the minimum value, and the crank angle change by a predetermined angle. You may make it detect the intake-pressure fluctuation amount in a predetermined period, or the change speed of intake pressure. In short, the value detected through the intake pressure sensors 52a and 52b can be arbitrarily changed as long as it is an aspect of the intake pressure fluctuation that can accurately detect the variation in the intake air amount through the comparison.

  The present invention is also applicable to an internal combustion engine in which lift operating angles are set such that lift operating angles of a plurality of exhaust valves corresponding to the same bank overlap. In this configuration, it is also possible to provide the internal combustion engine with an exhaust collecting passage common to both banks.

  The present invention can also be applied to an internal combustion engine set in advance so that the lift operating angles of a plurality of intake valves corresponding to the same bank do not overlap in any engine operating state.

  The present invention can be applied not only to an 8-cylinder internal combustion engine having a V-type cylinder arrangement, but also to an internal combustion engine such as a 4-cylinder, a 6-cylinder, a 10-cylinder, or a 12-cylinder having a V-type cylinder arrangement. It is.

  The present invention is not limited to an internal combustion engine having a V-type cylinder arrangement, but can be applied to an internal combustion engine having an in-line cylinder arrangement. In this case, for example, the internal combustion engine may be configured as follows. That is, first, all the cylinders of the internal combustion engine are divided into two or more cylinder groups configured by only cylinders that can be in a state where the lift operation angles of the intake valves do not overlap each other. An intake manifold passage, a surge tank, and an intake pressure sensor are provided for each cylinder group.

  As shown in FIG. 10, in an internal combustion engine having an in-line cylinder arrangement, the lift operating angle that can be set so that the lift operating angle of the intake valve does not overlap as the number of cylinders increases. The setting range (range shown by hatching in the figure) becomes narrower. Therefore, the greater the number of cylinders, the lower the degree of freedom for setting the intake valve lift operating angle.

  In this regard, if the ignition sequence of the internal combustion engine is set so that the cylinders constituting the same cylinder group are not continuously ignited, the settable range for the lift operating angle of the intake valve is increased. The degree of freedom for setting the lift operating angle can be maintained high. Furthermore, for each of these cylinder groups, by providing a collective passage where exhaust branch passages connected to each cylinder are connected to each other, the degree of freedom in setting the lift working angle of the exhaust valve is also improved. Can be kept high.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of one Embodiment which actualized the internal combustion engine concerning this invention. The graph which shows the change aspect of the lift working angle of an intake valve based on the action | operation of a working angle change mechanism. FIG. 2 is a schematic configuration diagram of an intake system and an exhaust system of the internal combustion engine according to the same embodiment. FIG. 3 is a stroke diagram of the internal combustion engine according to the same embodiment. The time chart which shows (a) transition of the intake flow rate in the A bank intake system during engine low load operation, and (b) transition of the intake pressure. The time chart which shows (a) transition of the intake flow rate in the intake system of B bank during engine low load operation, and (b) transition of the intake pressure. The time chart which shows (a) transition of the intake flow rate in the intake system of the internal combustion engine of the comparative example A, and (b) transition of the intake pressure. The graph which shows an example of the relationship between the gap | interval which intake air passes, and the lift working angle of an intake valve. (A) And (b) Sectional drawing which shows the intake valve at the time of valve opening, and its surrounding structure. The graph which shows the relationship between the number of cylinders of the internal combustion engine which has an in-line cylinder arrangement | sequence, and the setting range of the lift working angle of the intake valve which can be set so that it may not overlap.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Intake passage, 12 ... Throttle valve, 13 ... Throttle motor, 14 ... Combustion chamber, 15a, 15b ... Intake collecting passage, 16a, 16b ... Surge tank, 17a ... Intake branch passage, 18 ... Fuel injection Valve, 19 ... Spark plug, 20 ... Piston, 21 ... Crankshaft, 22 ... Exhaust passage, 23a, 23b ... Exhaust branch passage, 24a, 24b ... Exhaust collecting passage, 25a, 25b ... Exhaust purification catalyst, 26 ... Crankshaft, 30a, 30b ... intake valve, 32a, 32b ... exhaust valve, 34a ... intake camshaft, 36a ... exhaust camshaft, 38a, 38b ... working angle changing mechanism, 40a ... actuator, 50 ... electronic control unit, 52a, 52b ... suction Barometric sensor.

Claims (5)

There are a plurality of cylinder groups composed of only cylinders that can be in a state where the valve opening periods of the intake valves do not overlap each other, and for each cylinder group, a branch passage connected to each cylinder is gathered. An internal combustion engine comprising a collecting passage to be connected and a detection unit for detecting an intake pressure of the collecting passage. The internal combustion engine according to claim 1,
The internal combustion engine, wherein the cylinder group is configured only by cylinders whose valve opening periods of the exhaust valves do not overlap each other. The internal combustion engine according to claim 1 or 2,
An internal combustion engine, further comprising a change mechanism capable of changing the valve opening period so that the lift amount becomes smaller as the valve opening period of the intake valve is set shorter. The internal combustion engine according to claim 1 or 2,
The intake valve of each cylinder constituting the same cylinder group further includes a change mechanism that can be changed between a state in which the valve opening period overlaps and a state in which the valve opening period does not overlap,
The internal combustion engine, wherein the detection unit detects the intake pressure when the change mechanism is changed to the non-overlapping state. The internal combustion engine according to any one of claims 1 to 4,
The internal combustion engine has two banks, a cylinder group is set for each bank, and an ignition order is set so that ignition is performed alternately for each bank.

Images