JP2018168719A - Internal combustion engine - Google Patents

Abstract

To provide an internal combustion engine capable of suppressing a steep opening/closing action of an intake valve when performing an Atkinson cycle operation by quickly closing the intake valve in an intake process.SOLUTION: The present invention relates to an internal combustion engine comprising a valve opening/closing part for driving opening/closing of an intake valve which opens/closes an intake passage, a first exhaust valve which opens/closes a first exhaust passage, and a second exhaust valve which opens/closes a second exhaust passage. The valve opening/closing part has first valve timing in which the opening/closing of each of the valves is driven in such a manner that, exhaust air in a combustion chamber is exhausted to the first exhaust passage by opening the first exhaust valve in an exhaust process, an air-fuel mixture is supplied from the intake passage to the combustion chamber by opening the intake valve in an intake process, the intake valve is closed before an intake bottom dead point and a part of the air-fuel mixture in the combustion chamber is exhausted to the second exhaust passage by opening the second exhaust valve in a compression process. The first valve timing causes the air-fuel mixture flowing in the second exhaust passage to return to the intake passage.SELECTED DRAWING: Figure 3

Description

  The present invention relates to the technology of an internal combustion engine.

  Conventionally, by closing the closing timing of the intake valve in the intake process before the intake bottom dead center (by early closing of the intake valve), Atkinson reduces the actual compression ratio compared to the actual expansion ratio of the combustion chamber of the internal combustion engine Cycle operation is known. According to such an Atkinson cycle operation, the temperature in the combustion chamber in the compression process does not increase so much, so that the occurrence of knocking can be suppressed.

  Although it does not suppress the occurrence of knocking by performing Atkinson cycle operation, for example, Patent Document 1 discloses an intake passage that is independently connected to a combustion chamber and supplies an air-fuel mixture to the combustion chamber. An exhaust passage for exhausting the exhaust gas, a recirculation passage for recirculating exhaust from the combustion chamber to the intake passage, an intake valve for opening and closing the intake passage, a first exhaust valve for opening and closing the exhaust passage, and a second exhaust valve for opening and closing the recirculation passage And an internal combustion engine that returns exhaust gas from the combustion chamber to the intake passage through the recirculation passage when the opening and closing timing of the intake valve and the second exhaust valve overlap each other.

JP2015-209798A

  By the way, when performing an Atkinson cycle operation by quickly closing an intake valve in an intake process in a conventional internal combustion engine, in order to reduce the actual compression ratio of the combustion chamber and suppress the occurrence of knocking, a much shorter time than the normal operation And the same amount of air-fuel mixture needs to be supplied to the combustion chamber. That is, it is necessary to perform a sharp opening / closing operation of the intake valve so that the opening / closing period of the intake valve is made extremely shorter than that in the normal operation and the valve lift amount is made approximately the same. When performing such a sharp opening / closing operation of the intake valve, the supply pressure of the air-fuel mixture supplied to the combustion chamber may need to be set very high, or the pump loss of the combustion chamber may increase.

  Therefore, an object of the present invention is to provide an internal combustion engine capable of suppressing a sharp opening / closing operation of an intake valve when performing an Atkinson cycle operation by early closing of the intake valve in an intake process.

  The present invention includes an intake passage, a first exhaust passage and a second exhaust passage that are independently connected to a combustion chamber for burning an air-fuel mixture containing air and fuel, an intake valve for opening and closing the intake passage, and the first A first exhaust valve that opens and closes an exhaust passage, a second exhaust valve that opens and closes the second exhaust passage, and a valve opening and closing portion that opens and closes the intake valve, the first exhaust valve, and the second exhaust valve. The valve opening / closing part opens the first exhaust valve in the exhaust process, discharges the exhaust of the combustion chamber to the first exhaust passage, opens the intake valve in the intake process, and opens the intake passage from the intake passage. An air-fuel mixture is supplied to the combustion chamber, the intake valve is closed before the intake bottom dead center, the second exhaust valve is opened in the compression stroke, and a part of the air-fuel mixture in the combustion chamber is discharged to the second exhaust passage. Having a first valve timing for opening and closing each valve, Mixture flowing through the second exhaust passage by the valve timing, the engine, characterized in that return to the intake passage.

  Further, in the internal combustion engine, the valve opening / closing portion retards the opening / closing timing of the intake valve, advances the opening / closing timing of the second exhaust valve, and decreases the load of the internal combustion engine, It is preferable to perform at least one of increasing the operating angle of the valve and decreasing the operating angle of the second exhaust valve.

  The internal combustion engine further includes a second intake passage connected to the combustion chamber, the second exhaust valve opens and closes the second exhaust passage and the second intake passage, and the valve opening and closing portion In the step, the first exhaust valve is opened to exhaust the combustion chamber exhaust to the first exhaust passage. In the intake step, the intake valve and the second exhaust valve are opened, and the intake passage and the second intake valve are opened. A second valve timing for opening and closing each valve so as to supply an air-fuel mixture from a passage to the combustion chamber; in a predetermined high load region, the first valve timing is performed, and other than the high load region Then, it is preferable to perform the second valve timing.

  The internal combustion engine further includes a second intake passage connected to the combustion chamber, and a second intake valve that opens and closes the second intake passage, and the valve opening and closing portion includes the first exhaust valve in an exhaust process. And the exhaust gas in the combustion chamber is discharged into the first exhaust passage, and the intake valve and the second intake valve are opened in the intake step, and mixed into the combustion chamber from the intake passage and the second intake passage. A third valve timing for opening and closing each valve so as to supply air, the first valve timing is performed in a predetermined high load region, and the third valve timing is performed in a region other than the high load region. Preferably it is done.

  The internal combustion engine further includes a direct injection type fuel injector that directly injects fuel into the combustion chamber, and the closing timing of the second exhaust valve at the first valve timing is determined by fuel generated by the direct injection type fuel injector. It is preferable that it is before injection.

  According to the present invention, when performing an Atkinson cycle operation by early closing of an intake valve in an intake process, it is possible to suppress a sharp opening / closing operation of the intake valve.

It is a schematic structure figure showing an example of an internal-combustion engine concerning this embodiment. 2 is a partial schematic cross-sectional view showing a schematic configuration of a cylinder, an intake system, and an exhaust system. FIG. It is a figure which shows the 1st valve timing in the internal combustion engine of this embodiment. It is a figure which shows the valve timing of the Atkinson cycle driving | operation in the conventional internal combustion engine. It is a figure which shows the 1st valve timing which adjusted the opening / closing timing or operating angle of an intake valve or a 2nd exhaust valve with the fall of the load of an internal combustion engine. It is a schematic block diagram which shows another example of the internal combustion engine which concerns on this embodiment. It is a figure which shows the 2nd valve timing in the internal combustion engine of this embodiment. It is a schematic block diagram which shows another example of the internal combustion engine which concerns on this embodiment. It is a figure which shows the 3rd valve timing in the internal combustion engine of this embodiment.

  FIG. 1 is a schematic configuration diagram illustrating an example of an internal combustion engine according to the present embodiment. An internal combustion engine 100 shown in FIG. 1 is mounted on, for example, an automobile. An internal combustion engine 100 shown in FIG. 1 includes a cylinder 10, an intake passage 12, a first exhaust passage 14, a second exhaust passage 16, an exhaust recirculation passage 18, an intake valve 20, a first exhaust valve 22, a second exhaust valve 24, A feeder 28, an intercooler 30, an EGR cooler 32, a fuel injector 34, throttle valves 36a and 36b, an exhaust catalyst 38, an ECU 42, and a valve opening / closing unit (not shown) are provided. Although there is one cylinder 10 shown in FIG. The supercharger 28 includes a compressor 44 and a turbine 46. Although the internal combustion engine 100 shown in FIG. 1 includes a plug that performs spark ignition, the illustration thereof is omitted.

  The intake passage 12 and the first exhaust passage 14 are each connected to the cylinder 10. One end of the second exhaust passage 16 is connected to the cylinder 10, and the other end is connected to the intake passage 12 upstream from the compressor 44. One end of the exhaust gas recirculation passage 18 is connected to the first exhaust passage 14, and the other end is connected to the intake passage 12 downstream of the throttle valve 36a.

  The compressor 44 of the supercharger 28 is installed in the intake passage 12, and the turbine 46 of the supercharger 28 is installed in the first exhaust passage 14. The turbine 46 and the compressor 44 of the supercharger 28 are arranged on the same axis of the rotating shaft 48 and are integrally configured via the rotating shaft 48. The supercharger 28 uses the energy of the exhaust gas flowing through the first exhaust passage 14 to rotate the turbine 46, drives the compressor 44 with the rotational force of the turbine 46, and pressurizes the air flowing through the intake passage 12.

  The intercooler 30 is provided in the intake passage 12 downstream of the compressor 44 of the supercharger 28. By the intercooler 30, for example, air flowing through the intake passage 12 is heat-exchanged with cooling water and cooled.

  The fuel injector 34 is provided in the intake passage 12 downstream of the intercooler 30. Fuel is injected into the air flowing through the intake passage 12 by the fuel injector 34.

  The throttle valve 36 a is installed in the intake passage 12 downstream from the fuel injector 34. The flow rate of the air-fuel mixture flowing through the intake passage 12 is adjusted by the throttle valve 36a.

  The exhaust catalyst 38 is provided in the first exhaust passage 14 downstream of the turbine 46 of the supercharger 28. The exhaust catalyst 38 is, for example, a three-way catalyst or an oxidation catalyst, and purifies the exhaust gas flowing through the first exhaust passage 14.

  The EGR cooler 32 is provided in the exhaust gas recirculation passage 18. By the EGR cooler 32, for example, the exhaust gas (EGR gas) recirculated to the intake passage 12 is heat-exchanged with cooling water and cooled. The throttle valve 36 b is installed in the exhaust gas recirculation passage 18 downstream from the EGR cooler 32. The flow rate of the exhaust gas (EGR gas) flowing through the exhaust gas recirculation passage 18 is adjusted by the throttle valve 36b.

  Specific configurations of the intake system (the intake passage 12, the intake valve 20) and the exhaust system (the first exhaust passage 14, the second exhaust passage 16, the first exhaust valve 22, and the second exhaust valve 24) of the present embodiment will be described. .

  FIG. 2 is a partial schematic cross-sectional view showing a schematic configuration of a cylinder, an intake system, and an exhaust system. A piston 50 is disposed in the cylinder 10, and a combustion chamber 52 formed of an upper surface of the piston 50 and an inner peripheral wall of the cylinder 10 is formed. Although not shown, the piston 50 in the cylinder 10 is connected to the crankshaft via a crank mechanism. Although not shown, a crank angle sensor that detects the crank angle and the rotational speed of the internal combustion engine, a torque sensor that detects torque, a knocking sensor that detects knocking, and the like are provided in the vicinity of the crankshaft.

  The intake passage 12, the first exhaust passage 14, and the second exhaust passage 16 are independently connected to the upper portion of the combustion chamber 52. An intake valve 20 is installed in the intake passage 12, and the intake passage 12 is opened and closed by the intake valve 20. A first exhaust valve 22 is installed in the first exhaust passage 14, and the first exhaust passage 14 is opened and closed by the first exhaust valve 22. A second exhaust valve 24 is installed in the second exhaust passage 16, and the second exhaust passage 16 is opened and closed by the second exhaust valve 24.

  The valve opening / closing unit is configured to open and close the intake valve 20, the first exhaust valve 22, and the second exhaust valve 24 independently, and includes, for example, a cam shaft, a plurality of cams, a variable valve mechanism, and the like. (For example, refer to JP 2010-13940 A). Specifically, the camshaft rotates when the driving force is transmitted from the crankshaft via the timing belt. The plurality of cams are formed on the outer periphery of the cam shaft, and open and close the intake valve 20, the first exhaust valve 22, and the second exhaust valve 24 as the cam shaft rotates. The variable valve mechanism changes the opening / closing timing, lift amount, working angle, etc. of each valve by changing a cam provided on the cam shaft or a cam profile, for example.

  The valve opening / closing part opens the first exhaust valve 22 in the exhaust process to discharge the exhaust from the combustion chamber 52 to the first exhaust passage 14, and opens the intake valve 20 in the intake process to enter the combustion chamber 52 from the intake passage 12. Supply the air-fuel mixture, close the intake valve 20 before the intake bottom dead center, open the second exhaust valve 24 in the compression stroke, and discharge part of the air-fuel mixture in the combustion chamber 52 to the second exhaust passage 16. A first valve timing for opening and closing each valve is provided. Here, the intake bottom dead center refers to the crank angle at which the piston 50 has reached bottom dead center in the intake stroke. Note that the intake top dead center refers to the crank angle at which the piston 50 has reached top dead center in the intake process, and the exhaust top dead center refers to the crank angle at which the piston 50 has reached top dead center in the exhaust process, The exhaust bottom dead center is the crank angle at which the piston 50 has reached bottom dead center in the exhaust process. A specific example of the first valve timing will be described later.

  The ECU 42 is a well-known microcomputer configured by connecting a CPU, a RAM, a ROM, an A / D conversion element, a D / A conversion element, and the like with a bus. As shown in FIG. 1, the ECU 42 is electrically connected to a fuel injector 34, throttle valves 36a and 36b, and a spark plug (not shown). The ECU 42 acquires control information (data) such as the rotational speed of the internal combustion engine from the crank angle sensor, the torque of the internal combustion engine from the torque sensor, the knocking strength from the knock sensor, and the fuel injector based on the control information and the like 34, the throttle valves 36a and 36b and the spark plug are driven and controlled to adjust the fuel injection amount, the mixture flow rate, the exhaust flow rate, the ignition timing, and the like. Moreover, ECU42 is electrically connected with a valve opening / closing part, and controls the drive of a valve opening / closing part.

  Next, the operation of the internal combustion engine 100 will be described.

  In normal operation, a part of the exhaust gas combusted in the combustion chamber 52 of the cylinder 10 flows through the first exhaust passage 14 via the first exhaust valve 22, and rotates the turbine 46 of the supercharger 28. It is processed by the exhaust catalyst 38 and discharged out of the system. By the rotational drive of the turbine 46, the compressor 44 of the supercharger 28 is rotationally driven, and the air passing through the intake passage 12 is pressurized. The pressurized air is cooled by the intercooler 30 and then a predetermined amount of fuel is injected from the fuel injector 34. In addition, a part of the exhaust discharged from the cylinder 10 passes through the exhaust gas recirculation passage 18 and is cooled by the EGR cooler 32 to the intake passage 12 and then supplied to the intake passage 12. The flow rate of the air-fuel mixture (air and fuel) flowing through the intake passage 12 and the flow rate of exhaust gas passing through the exhaust gas recirculation passage 18 are adjusted by throttle valves 36a and 36b. The air-fuel mixture (air, fuel, exhaust gas mixture) flowing through the intake passage 12 is supplied to the combustion chamber 52 in the cylinder 10 via the intake valve 20. The air-fuel mixture in the combustion chamber 52 is ignited by a spark plug, and the piston 50 is driven by the pressure generated by the combustion of the air-fuel mixture. The air-fuel mixture combusted in the combustion chamber 52 is discharged to the first exhaust passage 14 through the first exhaust valve 22 as exhaust.

  For example, when the load of the internal combustion engine 100 increases and knocking occurs, it is preferable to perform the Atkinson cycle operation by early closing of the intake valve 20 in the intake process. In this case, the valve opening / closing section opens and closes the intake valve 20, the first exhaust valve 22, and the second exhaust valve 24 at the first valve timing. Specifically, the ECU 42 acquires torque (load) data and knocking strength data of the internal combustion engine 100 from the torque sensor and knock sensor, and if these values are equal to or greater than a preset threshold value, the ECU 42 A control signal is transmitted to the opening / closing section, and the valve opening / closing section drives each valve to open / close at the first valve timing.

  FIG. 3 is a diagram showing the first valve timing in the internal combustion engine of the present embodiment. In the figure, the vertical axis represents the valve lift amount, and the horizontal axis represents the crank angle of the piston 50. In addition, the opening / closing timing of each valve of FIG. 3 is an example, and is not limited to this.

  After the combustion in the combustion chamber 52, in the exhaust process, the first exhaust valve 22 is opened near the exhaust bottom dead center (crank angle 180 °), the piston 50 rises, and the exhaust top dead center (crank angle 360 °) To close the first exhaust valve 22. While the first exhaust valve 22 is open and the piston 50 is rising, the exhaust in the combustion chamber 52 is discharged from the first exhaust passage 14.

  In the intake process, the intake valve 20 is opened near the intake top dead center (crank angle near 360 °), the piston 50 is lowered, and the intake valve 20 is closed before the intake bottom dead center (before the crank angle 540 °). (See solid line in FIG. 3). By opening the intake valve 20, the air-fuel mixture (fuel, air, and exhaust) is supplied from the intake passage 12 into the combustion chamber 52. In addition, in order to suppress the occurrence of knocking, the intake valve 20 is quickly closed before the intake bottom dead center to reduce the actual compression ratio in the combustion chamber 52. In normal operation, for example, in the intake process, the intake valve 20 is opened near the intake top dead center, and the intake valve 20 is closed at the intake bottom dead center (see the broken line in FIG. 3).

  In the compression stroke in which the piston 50 moves up and the air-fuel mixture in the combustion chamber 52 is compressed, the second exhaust valve 24 is opened and closed, and a part of the air-fuel mixture in the combustion chamber 52 is exhausted to the second exhaust passage 16. Since the air-fuel mixture flowing through the second exhaust passage 16 is returned to the intake passage 12, fuel loss is suppressed. Further, in terms of preventing knocking, it is preferable to return the air-fuel mixture to the intake passage 12 upstream of the intercooler 30 to cool the air-fuel mixture.

  As described above, in the present embodiment, the second exhaust valve 24 is opened in the compression stroke, and a part of the air-fuel mixture in the combustion chamber 52 is exhausted. Even so, the reduction of the actual compression ratio in the combustion chamber 52 is ensured, and the occurrence of knocking is suppressed. That is, in the intake process, it is not necessary to make the opening / closing period of the intake valve 20 (the time from when the valve is opened until it is closed) extremely shorter than in the case of normal operation. Moreover, since the opening / closing period of the intake valve 20 can be lengthened to some extent, the valve lift amount can also be reduced. Therefore, when performing the Atkinson cycle operation by early closing of the intake valve 20 in the intake process, the rapid opening / closing operation of the intake valve 20 can be suppressed by driving the valves to open / close at the first valve timing as described above.

  FIG. 4 is a diagram showing valve timings of Atkinson cycle operation in a conventional internal combustion engine. When performing an Atkinson cycle operation in a conventional internal combustion engine, since a part of the air-fuel mixture in the combustion chamber is not exhausted during the compression stroke as in this embodiment, the intake valve opening / closing period indicated by the solid line in FIG. With this increase, it is necessary to make the time extremely shorter than in the case of the normal operation shown by the broken line in FIG. In order to supply the same amount of air-fuel mixture as that in the normal operation to the combustion chamber during a short opening / closing timing of the intake valve, it is necessary to set the valve lift to the same level as in the normal operation. Therefore, compared with the internal combustion engine of the present embodiment, the conventional internal combustion engine requires a sharp opening / closing operation of the intake valve when performing the Atkinson cycle operation by early closing of the intake valve in the intake process.

  The steep opening / closing operation of the intake valve requires that the supply pressure of the air-fuel mixture supplied to the combustion chamber (for example, the supercharging pressure of the supercharger) be set very high, or the pump loss of the combustion chamber increases. There is a case. However, in this embodiment, since a sharp opening / closing operation of the intake valve is suppressed, it is possible to reduce the supply pressure of the air-fuel mixture and the pump loss of the combustion chamber as compared with the conventional internal combustion engine.

  In the present embodiment, the opening / closing period of the intake valve 20 when the Atkinson cycle operation is performed at the first valve timing may be reduced by, for example, about 20% to 30% with respect to the opening / closing period of the intake valve 20 in the normal operation. The valve lift amount of the intake valve 20 can be reduced by, for example, 20% to 30% with respect to the valve lift amount of the intake valve 20 in normal operation. In the conventional internal combustion engine, the opening / closing period of the intake valve in the Atkinson cycle operation is reduced by, for example, 50% or more with respect to the opening / closing period of the intake valve in the normal operation, and the valve lift amount of the intake valve is, for example, the normal operation It is necessary to make it the same as the valve lift amount of the intake valve.

  FIG. 5 is a diagram illustrating a first valve timing in which the opening / closing timing or the operating angle of the intake valve or the second exhaust valve is adjusted in accordance with a decrease in the load of the internal combustion engine. Here, the working angle refers to an opening time area which is a value obtained by integrating the lift amount of each valve with time. That is, the increase in the working angle described below means that the lift amount and the opening / closing period are increased, and the reduction of the working angle means that the lift amount and the opening / closing period are reduced. In addition, the advance angle of the opening / closing timing described below means that the operating angle is not changed and the valve opening / closing timing is advanced, and the retarding of the opening / closing timing is not changed and the valve opening / closing timing is not changed. It means delaying the time.

  For example, when the ECU 42 acquires torque (load) data of the internal combustion engine 100 from the torque sensor and these values are equal to or less than a preset threshold value, a control signal is transmitted from the ECU 42 to the valve opening / closing unit, The valve opening / closing part changes the opening / closing timing or operating angle of the intake valve 20 and the second exhaust valve 24 as follows. For example, as shown in FIG. 5A, the opening / closing timing of the intake valve 20 is retarded. That is, the opening / closing timing of the intake valve 20 is shifted to the intake bottom dead center side (crank angle 540 ° side). However, since it is the first valve timing (Atkinson cycle operation), the intake valve 20 is closed before the intake bottom dead center. Further, for example, as shown in FIG. 5B, the opening / closing timing of the second exhaust valve 24 is advanced. That is, the opening / closing timing of the second exhaust valve 24 is shifted to the intake bottom dead center side (crank angle 540 ° side). Further, for example, as shown in FIG. 5C, the operating angle of the intake valve 20 is increased. In FIG. 5C, both the opening / closing period and the lift amount of the intake valve 20 are increased, but either one may be sufficient. Further, for example, as shown in FIG. 5D, the working angle of the second exhaust valve 24 is reduced. In FIG. 5D, both the opening / closing period and the lift amount of the second exhaust valve 24 are reduced, but either one may be sufficient. By adjusting the opening / closing timing or operating angle of the intake valve 20 and the second exhaust valve 24 as described above, the pump loss of the combustion chamber 52 and the supercharging pressure of the air-fuel mixture by the supercharger 28 can be further reduced. Although the reduction rate of the actual compression ratio of the internal combustion engine is alleviated by adjusting the opening / closing timing or the working angle of the intake valve 20 and the second exhaust valve 24 as described above, the load of the internal combustion engine is reduced and the occurrence rate of knocking is reduced. The impact on knocking is small.

  The adjustment of the opening / closing timing or the working angle of the intake valve 20 and the second exhaust valve 24 is not limited to the case where the adjustment is performed based on the preset threshold value as described above. You may carry out continuously. Further, although the torque data detected by the torque sensor is used as the load of the internal combustion engine 100, any data that can determine increase / decrease in the load of the internal combustion engine 100 may be used. For example, knocking intensity data detected by the knocking sensor May be used.

  FIG. 6 is a schematic configuration diagram illustrating another example of the internal combustion engine according to the present embodiment. In the internal combustion engine 200 shown in FIG. 6, the same components as those in the internal combustion engine 100 shown in FIG. The internal combustion engine 200 shown in FIG. 6 includes a second intake passage 54. One end of the second intake passage 54 is connected to the intake passage 12 downstream of the intercooler 30 and upstream of the throttle valve 36a. The other end of the second intake passage 54 joins the second exhaust passage 16 to form one pipe, and is connected to the combustion chamber 52 of the cylinder 10. The second exhaust valve 24 is provided in the pipe, and the second intake valve 54 and the second exhaust passage 16 are opened and closed by the second exhaust valve 24.

  The valve opening / closing part opens the first exhaust valve 22 in the above-described first valve timing and exhaust process, and exhausts the exhaust of the combustion chamber 52 to the first exhaust passage 14, and in the intake process, the intake valve 20 and the second exhaust And a second valve timing for opening and closing each valve so that the air-fuel mixture is supplied from the intake passage 12 and the second intake passage 54 to the combustion chamber 52 by opening the valve 24.

  The valve opening / closing section drives the valves to open and close at a first valve timing in a preset high load region, and drives the valves to open and close at a second valve timing outside the preset high load region. Here, the high load region is, for example, an operating state of the internal combustion engine in which the torque data detected from the torque sensor is equal to or higher than a threshold value, or an operating state of the internal combustion engine in which the knocking intensity data detected from the knocking sensor is equal to or higher than the threshold value. It is.

<Open / close drive of each valve by the first valve timing>
The ECU 42 acquires torque data or knocking strength data of the internal combustion engine 100 from the torque sensor or knock sensor, and when these values are equal to or greater than a preset threshold value, a control signal is transmitted from the ECU 42 to the valve opening / closing unit. The valve opening / closing unit drives each valve to open and close at the first valve timing. The opening / closing drive of each valve by the first valve timing is as described above, and the description thereof is omitted (see FIG. 3). Note that at the first valve timing, the second exhaust valve 24 is opened and closed during the compression stroke so that a part of the air-fuel mixture exhausted to the second exhaust passage 16 is communicated with the second exhaust passage 16. Since there is a case where the air-fuel mixture leaks to the passage 54 side or the air-fuel mixture flowing through the second intake passage 54 flows into the combustion chamber 52, a valve is installed in the second intake passage 54 so 2 It is desirable to keep the valve installed in the intake passage 54 closed.

<Open / close drive of each valve by the second valve timing>
When the ECU 42 acquires torque data or knocking strength data of the internal combustion engine 100 from the torque sensor or knocking sensor, and these values are less than a preset threshold value, a control signal is transmitted from the ECU 42 to the valve opening / closing unit. The valve opening / closing unit drives each valve to open and close at the second valve timing.

  FIG. 7 is a diagram showing the second valve timing in the internal combustion engine of the present embodiment. In the figure, the vertical axis represents the valve lift amount, and the horizontal axis represents the crank angle of the piston 50. In addition, the opening / closing timing of each valve of FIG. 7 is an example, and is not limited to this.

  After the combustion in the combustion chamber 52, in the exhaust process, the first exhaust valve 22 is opened near the exhaust bottom dead center (crank angle 180 °), the piston 50 rises, and the exhaust top dead center (crank angle 360 °) To close the first exhaust valve 22. While the first exhaust valve 22 is open and the piston 50 is rising, the exhaust in the combustion chamber 52 is discharged from the first exhaust passage 14.

  In the intake process, the intake valve 20 is opened near the intake top dead center (crank angle of 360 °), then the second exhaust valve 24 is opened, and the intake valve 20 is closed at the intake bottom dead center (crank angle of 540 °). The second exhaust valve 24 is closed after a predetermined time has elapsed from the intake bottom dead center. By opening the intake valve 20 and the second exhaust valve 24, the air-fuel mixture is supplied from the intake passage 12 and the second intake passage 54 into the combustion chamber 52. Note that at the second valve timing, a part of the air-fuel mixture flowing through the second intake passage 54 may leak to the second exhaust passage 16 side communicating with the second intake passage 54, so that the valve is connected to the second exhaust passage 16. It is desirable that the valve installed in the second exhaust passage 16 be closed during the second valve timing.

  Thus, by supplying the air-fuel mixture from the two intake passages 12 and the second intake passage 54 to the combustion chamber 52, the amount of air-fuel mixture supplied from each passage can be adjusted. Thermal efficiency can be improved. In particular, as shown in the figure, it is preferable to open the second exhaust valve 24 and supply the air-fuel mixture from the second intake passage 54 after the intake valve 20 is opened and the air-fuel mixture is supplied from the intake passage 12.

  FIG. 8 is a schematic configuration diagram illustrating another example of the internal combustion engine according to the present embodiment. In the internal combustion engine 300 shown in FIG. 8, the same components as those of the internal combustion engine 100 shown in FIG. The internal combustion engine 300 shown in FIG. 8 includes a second intake passage 54 and a second intake valve 56. One end of the second intake passage 54 is connected to the intake passage 12 downstream of the intercooler 30 and upstream of the throttle valve 36a. The other end of the second intake passage 54 is connected to the combustion chamber 52 of the cylinder 10. A second intake valve 56 is installed in the second intake passage 54, and the second intake passage 54 is opened and closed by the second intake valve 56.

  The valve opening / closing part opens the first exhaust valve 22 in the above-described first valve timing and exhaust process, and discharges the exhaust of the combustion chamber 52 to the first exhaust passage 14, and in the intake process, the intake valve 20 and the second intake valve And a third valve timing for opening and closing the valves so that the air-fuel mixture is supplied from the intake passage 12 and the second intake passage 54 to the combustion chamber 52. The valve opening / closing section drives the valves to open and close at a first valve timing in a preset high load region, and drives the valves to open and close at a third valve timing outside the preset high load region.

<Open / close drive of each valve by the first valve timing>
The ECU 42 acquires torque data or knocking strength data of the internal combustion engine 100 from the torque sensor or knock sensor, and when these values are equal to or greater than a preset threshold value, a control signal is transmitted from the ECU 42 to the valve opening / closing unit. The valve opening / closing unit drives each valve to open and close at the first valve timing. The opening / closing drive of each valve by the first valve timing is as described above, and the description thereof is omitted (see FIG. 3).

<Open / close drive of each valve at the third valve timing>
When the ECU 42 acquires torque data or knocking strength data of the internal combustion engine 100 from the torque sensor or knocking sensor, and these values are less than a preset threshold value, a control signal is transmitted from the ECU 42 to the valve opening / closing unit. The valve opening / closing section drives each valve to open and close at the third valve timing.

  FIG. 9 is a diagram showing the third valve timing in the internal combustion engine of the present embodiment. In the figure, the vertical axis represents the valve lift amount, and the horizontal axis represents the crank angle of the piston 50. In addition, the opening / closing timing of each valve of FIG. 9 is an example, and is not limited to this.

  After the combustion in the combustion chamber 52, in the exhaust process, the first exhaust valve 22 is opened near the exhaust bottom dead center (crank angle 180 °), the piston 50 rises, and the exhaust top dead center (crank angle 360 °) To close the first exhaust valve 22. While the first exhaust valve 22 is open and the piston 50 is rising, the exhaust in the combustion chamber 52 is discharged from the first exhaust passage 14.

  In the intake process, the intake valve 20 is opened near the intake top dead center (crank angle of 360 °), then the second intake valve 56 is opened, and the intake valve 20 is opened near the intake bottom dead center (crank angle of 540 °). The second intake valve 56 is closed after a predetermined time has elapsed from the intake bottom dead center. By opening the intake valve 20 and the second intake valve 56, the air-fuel mixture is supplied from the intake passage 12 and the second intake passage 54 into the combustion chamber 52.

  Thus, by supplying the air-fuel mixture from the two intake passages 12 and the second intake passage 54 to the combustion chamber 52, the amount of air-fuel mixture supplied from each passage can be adjusted. Thermal efficiency can be improved. In particular, as shown in the figure, it is preferable to open the second intake valve 56 and supply the air-fuel mixture from the second intake passage 54 after the intake valve 20 is opened and the air-fuel mixture is supplied from the intake passage 12.

  In the above embodiments, the internal combustion engine in which the fuel injector 34 is disposed in the intake passage 12 has been described. However, the fuel injector 34 may be a direct injection type fuel injector that directly injects fuel into the combustion chamber 52. In this case, it is preferable that the closing timing of the second exhaust valve 24 at the first valve timing is before fuel injection by the direct injection type fuel injector. As a result, the fuel injected by the direct injection fuel injector is suppressed from being discharged from the second exhaust passage 16 via the second exhaust valve 24.

  Further, in the present embodiment, the opening / closing drive of each valve is performed by the valve opening / closing unit using the cam as described above. However, the present invention is not necessarily limited to this, and for example, an electromagnetic drive system or the like may be used. The electromagnetically driven valve opening / closing unit includes, for example, an electric actuator installed in each valve and a drive circuit. A control signal for the valve timing of each valve is transmitted from the ECU 42 to the drive circuit. The drive circuit drives the electric actuator based on the control signal to drive the valves to open and close.

  10 cylinders, 12 intake passages, 14 first exhaust passages, 16 second exhaust passages, 18 exhaust recirculation passages, 20 intake valves, 22 first exhaust valves, 24 second exhaust valves, 28 superchargers, 30 intercoolers, 32 EGR Cooler, 34 Fuel injector, 36a, 36b Throttle valve, 38 Exhaust catalyst, 44 Compressor, 46 Turbine, 48 Rotating shaft, 50 Piston, 52 Combustion chamber, 54 Second intake passage, 56 Second intake valve, 100, 200, 300 Internal combustion engine.

Claims (5)

An intake passage, a first exhaust passage, and a second exhaust passage that are independently connected to a combustion chamber that burns an air-fuel mixture containing air and fuel;
An intake valve for opening and closing the intake passage; a first exhaust valve for opening and closing the first exhaust passage; a second exhaust valve for opening and closing the second exhaust passage;
A valve opening / closing unit that opens and closes the intake valve, the first exhaust valve, and the second exhaust valve;
The valve opening / closing part opens the first exhaust valve in the exhaust process, discharges the exhaust of the combustion chamber to the first exhaust passage, opens the intake valve in the intake process, and opens the intake chamber from the intake passage. So that the air-fuel mixture is supplied and the intake valve is closed before the intake bottom dead center, the second exhaust valve is opened in the compression stroke, and a part of the air-fuel mixture in the combustion chamber is discharged to the second exhaust passage. An internal combustion engine having a first valve timing for opening and closing each valve, and an air-fuel mixture flowing through the second exhaust passage at the first valve timing returns to the intake passage.   The valve opening / closing part retards the opening / closing timing of the intake valve, advances the opening / closing timing of the second exhaust valve, and increases the operating angle of the intake valve as the load of the internal combustion engine decreases. 2. The internal combustion engine according to claim 1, wherein at least one of reducing the operating angle of the second exhaust valve is performed. A second intake passage connected to the combustion chamber; the second exhaust valve opens and closes the second exhaust passage and the second intake passage;
The valve opening / closing part opens the first exhaust valve in the exhaust process, discharges the exhaust of the combustion chamber to the first exhaust passage, opens the intake valve and the second exhaust valve in the intake process, There is a second valve timing for opening and closing each valve so that air-fuel mixture is supplied from the intake passage and the second intake passage to the combustion chamber. In a predetermined high load region, the first valve timing is set. The internal combustion engine according to claim 1, wherein the second valve timing is performed outside the high load region. A second intake passage connected to the combustion chamber, and a second intake valve for opening and closing the second intake passage,
The valve opening / closing part opens the first exhaust valve in the exhaust process, discharges the exhaust of the combustion chamber to the first exhaust passage, opens the intake valve and the second intake valve in the intake process, A third valve timing for opening and closing each valve so as to supply an air-fuel mixture from the intake passage and the second intake passage to the combustion chamber. In a predetermined high load region, the first valve timing is set. The internal combustion engine according to claim 1, wherein the third valve timing is performed outside the high load region. A direct injection injector for directly injecting fuel into the combustion chamber;
5. The internal combustion engine according to claim 1, wherein the closing timing of the second exhaust valve at the first valve timing is before fuel injection by the direct injection injector.

Images