JP2018145848A - Engine system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine system capable of securing engine output by increasing an intake air amount of an engine even under an engine operation condition outside of an operation range of a supercharger, and enlarging the engine operation condition capable of being coped with a single supercharger.SOLUTION: An engine system 10 includes an engine 20, a plurality of intake ports 23, 24 connected to a combustion chamber of the engine 20, an intake passage 30 connected to each of the plurality of intake ports 23, 24, and a supercharger 50 for pressurizing the air flowing through the intake passage 30. The intake passage 30 has a first flow channel for guiding the pressurized air pressurized by the supercharger 50 to the plurality of intake ports 23, 24, and a second flow channel for guiding the air by natural intake to the second intake port 24. When an engine operation condition is outside of an operation range of the supercharger 50, the air by natural intake is guided to the second intake port 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine system including an engine and a supercharger that pressurizes air taken in by the engine.

  A supercharger is a device that increases the flow rate of air sucked into a combustion chamber of an engine by pressurizing air flowing through an intake passage of the engine system to increase the output of the engine. By improving the efficiency of the turbocharger, it can be expected that the entire engine system will be highly efficient. Here, the operating range of the supercharger differs depending on its capacity, and suitable operating conditions exist.

  Patent Document 1 discloses a turbocharging system that includes a high-pressure stage turbocharger and a low-pressure stage turbocharger, and the high-pressure stage turbocharger includes an electric motor that assists the driving force of the high-pressure stage compressor. A turbocharger system, which is an assist turbocharger, is described. According to Patent Document 1, it is possible to obtain a sufficient boost pressure by driving an electric motor even in a region where the engine speed is extremely low, and power performance in a region where the engine speed is extremely low (very low speed). Torque).

  Patent Document 2 includes a large turbocharger and a small turbocharger. The turbine of the small turbocharger is arranged upstream of the exhaust passage with respect to the turbine of the large turbocharger. A turbocharged engine, wherein the compressor of the turbocharger is disposed downstream of the intake passage relative to the compressor of the large turbocharger, and further includes assist drive means for assisting rotation of the compressor of the large turbocharger. Has been. According to Patent Document 2, the compressor of the large turbocharger is rotationally driven by the assist drive means to pressurize the intake air, and the pressurized intake air is further introduced into the compressor of the small turbocharger for further pressurization. Therefore, it is possible to efficiently perform supercharging while sharing it with both large and small turbochargers, and to obtain a high supercharging pressure as a whole even if the assist force by the assist drive means is not set so large It is said that you can.

JP 2012-97606 A JP 2011-58400 A

  For example, the normal engine rotation speed range is 3000 rpm or less, but in an engine system having a supercharger that is highly efficient for such low rotation conditions, the engine requires a high air volume. When the engine is operated under rotational conditions, there is a problem that the actual intake air amount of the engine does not increase and the engine output decreases due to reaching the upper limit of the operating flow rate of the supercharger. The technologies described in Patent Document 1 and Patent Document 2 both have a wide range of engine operating conditions by using a plurality of superchargers suitable for different engine operating conditions according to the engine operating conditions. It is intended to respond to.

  However, providing a plurality of superchargers in the engine system increases the cost per engine and complicates the mechanism for controlling the plurality of superchargers. Therefore, there is a demand for an engine system that can satisfy the required air amount of the engine under a wide range of engine operating conditions and achieve higher output and higher efficiency while having a simpler configuration.

  An object of the present invention is an engine system that includes an engine and a supercharger that pressurizes air taken in by the engine, and increases the intake air amount of the engine even under engine operating conditions outside the operating range of the supercharger. And providing an engine system capable of ensuring engine output.

  An engine system according to the present invention is provided in an engine, a plurality of intake ports connected to a combustion chamber of the engine, an intake passage connected to each of the plurality of intake ports, and the intake passage. An engine system comprising a supercharger that pressurizes flowing air, wherein the intake passage includes a first flow path that guides pressurized air pressurized by the supercharger to the plurality of intake ports, A second flow path for guiding air by intake air to at least one of the plurality of intake ports.

  In a preferred aspect, the apparatus further comprises a first gate valve provided in the first flow path and a second gate valve provided in the second flow path, and opens and closes the first gate valve and the second gate valve. And it is comprised so that the air led to the intake port connected with both the said 1st flow path and the said 2nd flow path may be switched to either one of the pressurized air by the said supercharger, and the air by natural intake.

  In another preferred aspect, when the required air amount of the engine is equal to or less than a predetermined value, the pressurized air from the supercharger is guided to an intake port communicating with both the first flow path and the second flow path. When the required air amount of the engine is larger than a predetermined value, air by natural intake is guided to an intake port communicating with both the first flow path and the second flow path.

  In another preferred aspect, the supercharger is a small supercharger.

  In another preferred aspect, the supercharger is a supercharger having high supercharging efficiency when the engine is operating at a low rotation condition.

  In another preferred aspect, the apparatus further includes a recirculation device that connects the exhaust passage of the combustion chamber and the intake passage to recirculate the exhaust gas.

  According to the engine system of the present invention, in the intake passage of the engine system, the first flow path that guides the pressurized air by the supercharger to the plurality of intake ports, and the air by natural intake to the at least one of the intake ports. When the engine operating conditions deviate from the operating range of the supercharger, the intake air amount of the engine is increased by guiding the air by natural intake to at least one intake port when the engine operating condition is outside the operating range of the supercharger. Output can be secured. As a result, it is possible to expand engine operating conditions that can be handled by a single supercharger.

It is a figure showing composition of an engine system concerning an example of this embodiment. It is a graph which shows an example of the compressor characteristic map of a supercharger. It is a graph which shows an example of the relationship between the rotation speed of an engine, and the air flow rate of each intake port. It is a graph which shows an example of the relationship between the rotation speed of an engine, and an output. It is a figure which shows the structure of the engine system which concerns on the modification of this embodiment. It is a figure which shows the structure of the conventional engine system.

  Hereinafter, an engine system according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an overall configuration of an engine system 10 according to the present embodiment. The engine system 10 includes an intake passage 30 through which intake air flows and an exhaust passage 60 through which exhaust flows. A supercharger 50 is provided in the intake passage 30, and the intake passage 30 is connected to a combustion chamber (not shown) of the engine 20 via a first intake port 23 and a second intake port 24.

  The engine 20 includes a piston therein, and a combustion chamber including an upper surface of the piston and an inner surface of the cylinder head is formed. For convenience of explanation, FIG. 1 shows an internal combustion engine having only one cylinder, but the engine used in the present invention has two or more cylinders, for example, a four-cylinder row engine. It may be.

  The intake passage 30 communicates with the combustion chamber via the first intake port 23 and the second intake port 24. The first intake port 23, the second intake port 24, and the combustion chamber are respectively connected to the first intake port. A valve 21 and a second intake valve 22 are provided. By opening and closing these intake valves, air taken from the atmosphere is supplied to the combustion chamber via the intake ports 23 and 24. The detailed structure of the intake passage 30 will be described later. In FIG. 1, the flow of intake and exhaust is indicated by white arrows. The engine 20 shown in FIG. 1 has two intake ports for one combustion chamber, but the number of intake ports is not limited to two, and three or more intake ports for one combustion chamber. You may have a port.

  The exhaust passage 60 is connected to the combustion chamber via the exhaust port 26. The exhaust port 26 is provided with an exhaust valve 25, and exhaust gas generated by combustion is discharged to the exhaust passage 60 through the exhaust port 26 by the operation of the exhaust valve 25.

  The engine system 10 according to the present embodiment includes a supercharger 50 that is provided in the intake passage 30 and pressurizes the air introduced into the combustion chamber. A turbocharger 50 shown in FIG. 1 is a turbocharger having a compressor 52 and a turbine 51. The compressor 52 is provided in a main intake pipe 32 described later, and the turbine 51 is provided in an exhaust passage 60.

  Exhaust gas discharged from the combustion chamber is guided to the turbine 51 through the exhaust port 26 and the exhaust passage 60. This exhaust gas flow serves as a power source for driving the turbine 51 and further for driving the compressor 52. The air flowing through the main intake pipe 32 is sucked into the compressor 52, compressed by driving the compressor 52, and sent out as pressurized air. An intercooler 53 is provided downstream of the compressor 52 to cool the pressurized air that has become hot immediately after compression. The cooled pressurized air is supplied into the combustion chamber of the engine 20 through the first intake port 23 and the second intake port 24.

  FIG. 2 is a graph showing an example of the compressor characteristic map of the supercharger 50, and shows the relationship between the intake air amount of the compressor 52 indicated by the horizontal axis and the compressor pressure ratio indicated by the vertical axis. The intake air amount and the supercharging pressure increase as the compressor rotational speed increases, but the compressor rotational speed has an upper limit, which limits the intake air amount and the supercharging pressure. A broken line Y shown in FIG. 2 indicates the upper limit of the operating range of the supercharger 50, and corresponds to the upper limit of the compressor rotation speed. The operating range of the supercharger 50 is limited to the lower left region of the broken line Y, and the supercharger 50 is not operated in the right and upper regions of the broken line Y. In addition, the upper limit of the compressor rotation speed of the supercharger 50 is determined, for example, in view of the compatibility between structural requirements such as strength against load and heat resistance and high efficiency.

  A region X indicated by hatching in FIG. 2 is a high efficiency region in which the supercharger 50 performs supercharging with a relatively high supercharging efficiency. When the intake air amount and the compressor pressure ratio of the supercharger 50 are within the region X, the supercharging efficiency is increased, and the efficiency of the entire engine system 10 is improved. Since the high efficiency region of the single supercharger 50 is not so wide, when selecting the supercharger 50 to be used for the engine system 10, considering the engine 20 displacement, the target engine operating conditions, etc. The supercharger 50 included in the region X is selected as much as possible for the operation of the supercharger 50 during the operation of the engine 20. For example, when targeting an engine system that operates under relatively low load conditions, the broken line Y moves to the low pressure / low flow rate side (lower left direction in FIG. 2), such as a small turbocharger with a small compressor capacity. A turbocharger with a relatively small compressor characteristic map range is selected.

  As will be described later, in the engine system 10 according to the present embodiment, the supercharger 50 that is set so that the supercharging efficiency becomes high when the engine 20 is operated under a low rotation condition, such as the small supercharger. It is particularly useful when used.

  The structure of the intake passage 30 provided in the engine system 10 according to the present embodiment will be described with reference to FIG.

  One common intake pipe 31 is provided on the most upstream side of the intake passage 30. The common intake pipe 31 is provided with an air intake (not shown) and an air cleaner (not shown) for removing dust and the like in order from the upstream side. The common intake pipe 31 branches into a main intake pipe 32 and a sub intake pipe 33 at the downstream end thereof.

  The main intake pipe 32 is provided with a first throttle valve 43, a compressor 52, an intercooler 53, and a first injector 45 in order from upstream to downstream. The compressor 52 and the intercooler 53 are as described above. The first throttle valve 43 is driven based on an output request from the driver, and controls the flow rate of air flowing through the main intake pipe 32 by adjusting the opening of the main intake pipe 32. The first injector 45, which is a fuel injection device, supplies fuel into the main intake pipe 32 and prepares an air-fuel mixture to be supplied to the combustion chamber. The main intake pipe 32 is provided with a flow meter (not shown) for detecting the air flow rate and an atmospheric pressure sensor (not shown) for detecting the air pressure. The main intake pipe 32 branches into a first intake port 23 and a pressurized air introduction pipe 34 at the downstream end thereof. The first intake port 23 guides pressurized air into the combustion chamber by opening and closing the first intake valve 21. The pressurized air introduction pipe 34 is connected to the upstream end of the second intake port 24 and guides the pressurized air flowing through the main intake pipe 32 to the second intake port 24. The pressurized air introduction pipe 34 is provided with a first gate valve 41, and by opening and closing the first gate valve 41, pressurized air from the supercharger 50 is introduced into or shut off from the second intake port 24.

  The auxiliary intake pipe 33 branches from the downstream end of the common intake pipe 31 with the main intake pipe 32 and is connected to the upstream end of the second intake port 24. Air that has not been pressurized by the supercharger 50 (hereinafter also referred to as “low pressure air”) is introduced into the second intake port 24 by natural intake through the auxiliary intake pipe 33. As shown in FIG. 1, the connecting portion between the auxiliary intake pipe 33 and the second intake port 24 is the downstream end of the pressurized air introduction pipe 34, in other words, the auxiliary intake pipe 33 and the pressurized air introduction pipe 34. Is the upstream end of the second intake port 24. The auxiliary intake pipe 33 is provided with a second gate valve 42. By opening and closing the second gate valve 42, low-pressure air is introduced into the second intake port 24 and shut off. The second intake port 24 is provided with a second throttle valve 44 and a second injector 46 in order from upstream to downstream.

  The intake passage 30 shown in FIG. 1 includes a first flow path that guides pressurized air pressurized by the supercharger 50 to the first intake port 23 and the second intake port 24, and air by natural intake as the second intake port. And a second flow path leading to 24. The first flow path is configured by the common intake pipe 31, the main intake pipe 32, and the pressurized air introduction pipe 34, and the second flow path is configured by the common intake pipe 31 and the auxiliary intake pipe 33.

  In the engine system 10 according to the present embodiment, by combining the opening and closing of the first gate valve 41 provided in the pressurized air introduction pipe 34 and the second gate valve 42 provided in the auxiliary intake pipe 33, the second intake port 24 and The air taken into the combustion chamber from the second intake valve 22 can be switched to either pressurized air or low pressure air by the supercharger 50. That is, by opening the first gate valve 41 and closing the second gate valve 42, the pressurized air from the supercharger 50 is guided to the second intake port 24 through the first flow path. Further, by closing the first gate valve 41 and opening the second gate valve 42, the low pressure air by natural intake is guided to the second intake port 24 through the second flow path. In the engine system 10, the first gate valve 41 and the second gate valve 42 are opened and closed based on instructions from the control unit 70.

  The second throttle valve 44 provided in the second intake port 24 has the same function as the first throttle valve 43 and is used when performing intake by natural intake through the second intake port 24. When the pressurized air is introduced into the second intake port 24, the amount of intake air is adjusted by the first throttle valve 43. Therefore, the second throttle valve 44 is controlled to maintain, for example, a fully open state. Similarly, the second injector 46 provided in the second intake port 24 has the same function as the first injector 45 and is used when intake by natural intake is performed via the second intake port 24. When the pressurized air is introduced into the second intake port 24, the fuel injection amount and the like are adjusted by the first injector 45. Therefore, the second injector 46 is controlled not to inject fuel, for example.

  The control unit 70 is a control device for controlling the engine system 10. The control unit 70 may be configured by a microcomputer, for example, and may be incorporated as a program in an electronic control unit (Electronic Control Unit: ECU). The control unit 70 includes a storage unit including a storage element such as a RAM and a ROM, a drive circuit for energizing each gate valve, and the like. The storage unit stores various control programs, data, maps, and the like, and the control unit 70 executes various controls by executing these control programs.

  The control unit 70 controls the opening and closing of the first gate valve 41 and the second gate valve 42 to switch the intake method to the second intake port 24. The opening and closing of the first gate valve 41 and the second gate valve 42 is controlled according to the required air amount of the engine 20. The control unit 70 outputs control signals for various actuators including, for example, the first injector 45, the second injector 46, the first throttle, the second throttle, the intake valve, and the exhaust valve 25, and controls them. The control unit 70 also receives various signals from various sensors including a flow meter, an intake pressure sensor, an accelerator opening sensor, and a crank angle sensor (engine speed sensor) provided in the intake passage 30.

  The required air amount of the engine 20 is a theoretical flow rate of the air sucked into the combustion chamber. For example, when the engine 20 is operated under a high load condition that requires a high output, the required air amount increases and a low output is sufficient. When operating under low load conditions, the required air volume is reduced. The required air amount is calculated by a predetermined map or function based on, for example, the engine speed, the opening of the first throttle, the atmospheric pressure (supercharging pressure) and the flow rate of the main intake pipe 32, and the like.

  Hereinafter, opening / closing control of the intake passage 30 and each gate valve in the engine system 10 according to the present embodiment will be described in detail with reference to FIGS. 2 to 4 and 6.

  FIG. 6 is a diagram showing a configuration of an example of a conventional engine system 90. About the engine system 90 shown in FIG. 6, the same code | symbol is attached | subjected to the structure similar to the engine system 10 shown in FIG. 1, or a corresponding structure, and the detailed description is abbreviate | omitted. The engine system 90 shown in FIG. 6 has only the main intake pipe 32 as the intake passage 20, and does not have the first gate valve 41, the second gate valve 42, the second throttle, and the second injector 46. 1 is different from the engine system 10 shown in FIG.

  In the conventional engine system 90, for example, as indicated by a point A in FIG. 2, when the required air amount of the engine 20 does not exceed the upper limit of the intake air amount of the supercharger 50, the supercharger 50 reduces the required air amount. Pressurized air can be supplied. On the other hand, as shown by a point B in FIG. 2, consider a case where the required air amount of the engine 20 exceeds the upper limit of the intake air amount of the supercharger 50. In this case, even if the pressurized air from the supercharger 50 is to be introduced into the combustion chamber from both the first intake port 23 and the second intake port 24, the required air amount exceeds the operating range of the supercharger 50. Actually, the pressurized air introduced into the combustion chamber is limited to the amount indicated by point C, and a flow rate higher than that cannot be supplied.

  FIG. 3 is a graph showing an example of the relationship between the engine speed and the air flow rate per actual time that actually flows through the intake ports 23 and 24. FIG. 4 is a graph showing an example of the relationship between the engine speed and the maximum load (torque) that can be output. 3 and 4, the characteristic of the conventional engine system 90 is indicated by a broken line, and the characteristic of the engine system 10 according to the present embodiment is indicated by a solid line. Further, points A to D in FIGS. 3 and 4 correspond to points A to D in FIG.

  As shown by the broken line in FIG. 3, in the conventional engine system 90, even if the rotational speed of the engine 20 is increased to satisfy the required air amount, the amount of pressurized air exceeding the upper limit of the intake air amount of the supercharger 50. Therefore, the air flow rate per real time actually flowing through the intake ports 23 and 24 remains constant. Since the air flow rate per real time is constant at the output of the engine 20, the air flow rate per cycle of the engine 20 decreases. As shown by the broken line in FIG. The maximum possible load is reduced.

  On the other hand, the engine system 10 according to the present embodiment includes the second flow path that allows natural intake through the second intake port 24, and compares the required air amount of the engine 20 with a predetermined reference value. The intake method from the second intake port 24 is switched by controlling the opening and closing of the first gate valve 41 and the second gate valve 42 according to the comparison result.

  Specifically, when the required air amount exceeds a predetermined reference value, the first gate valve 41 is closed, the second gate valve 42 is opened, and natural intake is performed via the second flow path and the second intake port 24. Air is introduced into the combustion chamber. As a result, even if the required air amount in the combustion chamber exceeds the upper limit of the intake air amount of the supercharger 50, natural intake is performed from the second intake port 24, and the pressurized air from the supercharger 50 is supplied to the first intake port. 23 only. The predetermined reference value to be compared with the required air amount is determined based on, for example, an upper limit (indicated by a broken line Y in FIG. 2) of the intake air amount of the supercharger 50.

  When natural intake is performed from the second intake port 24, the flow rate of low-pressure air increases in proportion to the engine speed, so that the flow rate of low-pressure air introduced from the second intake port 24 into the combustion chamber can be increased (see FIG. 3 (see solid line Q). On the other hand, since the flow rate of the pressurized air supplied by the supercharger 50 is sufficient to be introduced into the combustion chamber from the first intake port 23, the conventional engine system 90 indicated by point C as indicated by point D in FIG. Compared to the above, the intake air amount of the compressor 52 is much smaller. Therefore, the supercharger 50 can be operated within an operating range that does not exceed the upper limit of the compressor rotation speed, and the flow rate of the pressurized air introduced into the combustion chamber from the first intake port 23 can be increased (see the solid line P in FIG. 3). . Furthermore, as a result of the intake air amount of the engine 20 being increased by natural intake from the second intake port 24, the flow rate of the exhaust gas introduced into the turbine 51 is increased, and the compressor pressure ratio is increased. Thereby, compared with the conventional engine system 90, the flow volume of the pressurized air per one intake port also increases.

  As a result, in the engine system 10 according to the present embodiment, as shown by a solid line in FIG. 3, the actual air flow rate per actual time flows in both the first intake port 23 and the second intake port 24 as the engine rotation speed. Increases with increasing numbers. Further, as shown by a solid line in FIG. 4, the engine system 10 according to the present embodiment improves the maximum load that can be output by the engine 20 or suppresses the decrease even in the operation under a high load condition where the rotational speed is high. In addition, the maximum load that can be output can be remarkably improved with respect to the conventional engine system 90 indicated by a broken line in FIG.

  Further, in the engine system 10 according to this embodiment, when the required air amount is equal to or less than the predetermined reference value as a result of comparing the required air amount of the engine 20 with the predetermined reference value, the first gate valve 41 is opened. Then, the second gate valve 42 is closed, and pressurized air from the supercharger 50 is introduced into the combustion chamber from both the first intake port 23 and the second intake port 24. As a result, as long as the required air amount of the engine 20 does not exceed the upper limit of the intake air amount of the supercharger 50, supercharging by the supercharger 50 is performed to near the performance limit, and the maximum load that the engine 20 can output is increased. Can be increased.

  Hereinafter, the opening / closing control of each gate valve in the engine system 10 according to the present embodiment will be described more specifically. This control is repeatedly executed by the control unit 70 every predetermined time while the engine 20 is operating, for example.

  First, the required air amount of the engine 20 calculated based on the engine speed, the opening of the first throttle, the atmospheric pressure (supercharging pressure) and the flow rate of the main intake pipe 32, and the reference value stored in the storage unit Contrast with.

  As a result of the above comparison, when the required air amount is equal to or smaller than a predetermined reference value, the first gate valve 41 disposed in the main intake pipe 32 is opened, and the second gate valve 42 disposed in the auxiliary intake pipe 33 is opened. Closed. Further, the second throttle provided in the second intake port 24 is fully opened. As a result, the common intake pipe 31, the main intake pipe 32, the pressurized air introduction pipe 34, the first intake port 23, and the second intake port 24 are configured. A first flow path is formed through the first intake valve 21 and the second intake valve 22 to be introduced into the combustion chamber. The flow rate of the pressurized air supplied to the engine 20 is adjusted by the first throttle. The pressurized air after the metering is injected with fuel by the first injector 45 and is sucked into the combustion chamber from the first intake valve 21 and the second intake valve 22 as premixed air. As described above, by allowing the compressed air to be sucked into the combustion chamber from both the first intake port 23 and the second intake port 24, the engine can be operated under a highly efficient supercharging condition.

  As a result of the above comparison, when the required air amount exceeds a predetermined reference value, the first gate valve 41 disposed in the main intake pipe 32 is closed, and the second gate valve 42 disposed in the auxiliary intake pipe 33 is Open. Further, the second throttle provided in the second intake port 24 is fully opened. As a result, the first intake air that is constituted by the common intake pipe 31, the main intake pipe 32, and the pressurized air introduction pipe 34 and is pressurized by the compressor 52 of the supercharger 50 is introduced from the first intake port 23 into the combustion chamber. A flow path and a second flow path that is configured by the common intake pipe 31 and the auxiliary intake pipe 33 and guides low-pressure air that is natural intake air from the second intake port 24 into the combustion chamber are formed. As a result, the first intake port 23 and the second intake port 24 separate the flow path for introducing intake air.

  The flow rate of the pressurized air supplied from the first intake port 23 is adjusted by the first throttle, the fuel is injected by the first injector 45, and is sucked into the combustion chamber from the first intake valve 21 as premixed air. The The flow rate of the low-pressure air supplied from the second intake port 24 is adjusted by the second throttle, the fuel is injected by the second injector 46, and is sucked into the combustion chamber from the second intake valve 22 as premixed air. . In this way, pressurized air is sucked into the combustion chamber from the first intake port 23 and low-pressure air, which is natural intake air, is sucked into the combustion chamber from the second intake port 24, so that highly efficient supercharging conditions can be achieved. Engine operation is possible. As a result, the total amount of air flow supplied into the combustion chamber can be reduced even in engine operating conditions where the required air amount is high and the rotational speed is high compared to a conventional engine system 90 that does not have a bypass for naturally aspirating. The maximum load that can be output from the engine 20 can be greatly improved.

  The engine system 10 according to the present embodiment includes a supercharger 50 that is set to have a high supercharging efficiency when the engine 20 is operated under a low rotation condition, such as a small supercharger 50 having a small compressor capacity. This is particularly useful when using. In the conventional engine system 90, when the turbocharger 50 that is highly efficient for engine operation under a low rotation condition is used, the actual intake air of the engine 20 is obtained when the engine 20 is operated under a high rotation condition. There was a case where the engine output was reduced without increasing the amount. On the other hand, in the engine system 10 according to the present embodiment, even when the required air amount of the engine 20 is increased by performing natural intake at the second intake port 24 and supercharging only the first intake port 23. The actual intake air amount can be secured, and the engine output can be greatly improved as compared with the conventional engine system 90. In other words, even when using the supercharger 50 that achieves high efficiency under low rotation conditions, it is possible to improve engine output under high rotation / high load conditions such as when starting or accelerating. The usable range of the supercharger 50 can be expanded to the high rotation side.

  According to the present embodiment described above, the first flow path for guiding the pressurized air by the supercharger 50 to the plurality of intake ports 23 and 24 and the second flow path for guiding the air by natural intake to the second intake port 24. When the engine operating condition is such that the required air amount of the engine 20 increases and deviates from the operating range of the supercharger 50, air by natural intake is led to the second intake port 24, and supercharging is performed. The pressurized air from the machine 50 can be guided only to the first intake port 23. Thereby, the flow volume of the pressurized air which the supercharger 50 supplies is suppressed, and the driving | operation within the operating region of the supercharger 50 is enabled. Further, since the flow rate of the air guided from the second intake port 24 can be increased by natural intake, the total amount of intake air of the engine 20 is increased to satisfy the required air amount and ensure engine output. As a result, engine operating conditions that can be handled by a single supercharger 50 can be expanded.

  In the above description, the engine system 10 according to the present embodiment has been described based on an example in which the opening / closing control of each gate valve is performed according to the required air amount of the engine 20, but based on various numerical values other than the required air amount of the engine 20. Open / close control of each gate valve may be performed, for example, based on numerical values corresponding to or correlated with the required air amount, such as engine speed, pressure or flow rate in the main intake pipe 32, and the like. May be done. Further, in the engine system 10 according to the present embodiment, the opening / closing control of each gate valve by the control unit 70 is, for example, excessive speed such as the rotation speed of the compressor 52, the pressure ratio before and after the compressor 52, and the intake air amount of the compressor 52 You may perform based on the numerical value relevant to the driving | running state of the feeder 50. FIG.

  In the above description, the engine system 10 according to the present embodiment has been described with the turbocharger 50 having the compressor 52 and the turbine 51 as a turbocharger. For example, a mechanical supercharger or an electric supercharger may be used instead of the engine system 10 in which 50 is an exhaust turbine supercharger.

  FIG. 5 is a diagram showing a configuration of an engine system 80 according to a modification of the present embodiment. About the engine system 80 shown in FIG. 5, the same code | symbol is attached | subjected to the structure similar to the engine system 10 shown in FIG. 1, or a corresponding structure, and the detailed description is abbreviate | omitted.

  An engine system 80 shown in FIG. 5 includes an exhaust gas recirculation (EGR) device 81. The EGR device 81 includes an EGR introduction pipe 82, an EGR cooler 83 provided on the EGR introduction pipe 82, and an EGR valve 84. The EGR introduction pipe 82 is a flow path formed by branching the exhaust passage 60 from a flow path leading to the turbine 51 side. Thereby, a part of the exhaust gas discharged from the combustion chamber is led to the EGR introduction pipe 82 as EGR gas, and the rest is led to the turbine 51. The introduced high-temperature EGR gas is first cooled by the EGR cooler 83. The flow rate of the cooled EGR gas is adjusted by the EGR valve 84. The exhaust gas recirculation rate (EGR rate) of the engine 20 is controlled by adjusting the opening degree of the EGR valve 84 by the control unit 70. Next, the EGR gas is supplied to the second intake port 24 at the junction 85.

  Under the low rotation condition of the engine 20, the first gate valve 41 is opened, the second gate valve 42 is closed, and the second throttle is fully opened. As a result, a mixture of pressurized air, EGR gas, and fuel is drawn into the combustion chamber from both the first intake valve 21 and the second intake valve 22. Under the high rotation condition of the engine 20, the first gate valve 41 is closed and the second gate valve 42 is opened. As a result, a mixture of pressurized air and fuel is drawn into the combustion chamber from the first intake valve 21, and a mixture of low-pressure air, EGR and fuel is drawn into the combustion chamber from the second intake valve 22. . With such an EGR device 81, a part of the exhaust gas after combustion is sucked into the combustion chamber again, thereby suppressing the generation of nitrogen oxides (NOx) and the heat loss from the engine 20 due to the decrease in the combustion temperature. The fuel consumption rate can be improved by reducing the intake pipe negative pressure and the throttle loss.

10, 80, 90 Engine system, 20 Engine, 21 First intake valve, 22 Second intake valve, 23 First intake port, 24 Second intake port, 25 Exhaust valve, 26 Exhaust port, 30 Intake passage, 31 Common intake Pipe, 32 main intake pipe, 33 sub intake pipe, 34 pressurized air introduction pipe, 41 first gate valve, 42 second gate valve, 43 first throttle valve, 44 second throttle valve, 45 first injector, 46 first 2 injectors, 50 supercharger, 51 turbine, 52 compressor, 53 intercooler, 60 exhaust passage, 70 control unit, 81 exhaust gas recirculation device (EGR device), 82 EGR introduction pipe, 83 EGR cooler, 84 EGR valve, 85 Junction.

Claims (6)

Engine,
A plurality of intake ports connected to the combustion chamber of the engine;
An intake passage connected to each of the plurality of intake ports;
A supercharger provided in the intake passage and pressurizing air flowing through the intake passage;
An engine system comprising:
The intake passage is
A first flow path for guiding the pressurized air pressurized by the supercharger to the plurality of intake ports;
A second flow path for guiding air by natural intake to at least one of the plurality of intake ports;
Having an engine system. A first gate valve provided in the first flow path;
A second gate valve provided in the second flow path;
Further comprising
Air that opens and closes the first gate valve and the second gate valve and leads to an intake port that communicates with both the first flow path and the second flow path is generated by pressurized air and natural intake by the supercharger. Configured to switch to either air,
The engine system according to claim 1. When the required air amount of the engine is equal to or less than a predetermined value, the pressurized air by the supercharger is guided to an intake port communicating with both the first flow path and the second flow path,
When the required air amount of the engine is greater than a predetermined value, air by natural intake is led to an intake port communicating with both the first flow path and the second flow path.
The engine system according to claim 1 or 2. The supercharger is a small supercharger,
The engine system according to any one of claims 1 to 3. The supercharger is a supercharger having high supercharging efficiency when the operation of the engine is in a low rotation condition;
The engine system according to any one of claims 1 to 4. A recirculation device that connects the exhaust passage of the combustion chamber and the intake passage and recirculates the exhaust;
The engine system according to any one of claims 1 to 5.