JP4501730B2 - Variable cylinder internal combustion engine - Google Patents

Description

  The present invention divides a cylinder in a multi-cylinder internal combustion engine into a plurality of cylinder groups, and switches between a partial cylinder operation in which some cylinder groups are deactivated and an all cylinder operation in which all cylinder groups are operated according to the operating state. The present invention relates to a variable cylinder internal combustion engine.

  Conventionally, in a multi-cylinder internal combustion engine, fuel injection to some cylinders has been stopped in order to reduce fuel consumption in operating conditions that do not require much engine power, such as during idling or deceleration. Thus, partial cylinder operation is performed in which the engine is stopped (see, for example, Patent Document 1). In particular, in a V-type multi-cylinder internal combustion engine, it is known that cylinder deactivation and operation are controlled for each bank.

  Further, an internal combustion engine having an exhaust turbine driven supercharger (turbocharger, hereinafter referred to as “centrifugal supercharger”) driven by exhaust gas on an exhaust passage in the internal combustion engine is known (for example, , See Patent Document 2). This centrifugal supercharger uses the energy of exhaust gas discharged from the cylinder to rotate the turbine, compresses the air by a compressor attached to the same rotating shaft as the turbine, and feeds the compressed air into the cylinder. Device.

In the internal combustion engine that combines the above-described techniques, when the internal combustion engine is accelerated from the state in which the partial cylinder operation is performed, in the process in which the partial cylinder operation is released and the cylinders belonging to all banks operate. Since the rotational speed of the supercharger provided for the bank that has been stopped until then is low, the engine output of the internal combustion engine as a whole does not rise smoothly, and a step may be generated in the engine output. As a result, it may be difficult to obtain good acceleration performance.
JP-A-7-133716 JP-A-5-149142 JP-A-2-112619 Japanese Patent Laid-Open No. 1-216021

  The object of the present invention is to provide smooth engine output in the process of shifting from partial cylinder operation to full cylinder operation when the variable cylinder internal combustion engine is accelerated in a state where partial cylinder operation is performed. It is to provide a technology that can be raised.

  In order to achieve the above object, according to the present invention, when a variable cylinder internal combustion engine is accelerated from a state in which partial cylinder operation is performed, partial cylinder operation is performed before transition from partial cylinder operation to full cylinder operation. The main feature is that a part of the exhaust of the cylinder group that is operating in the engine is caused to flow into the exhaust passage of the cylinder group that is inactive and the turbocharger of the cylinder group that is inactive is driven by the exhaust. .

More specifically, a plurality of cylinders in the internal combustion engine are divided into two or more cylinder groups, and the partial cylinder operation for stopping fuel injection of the cylinders belonging to some cylinder groups according to the operation state of the internal combustion engine, and all the cylinders A variable-cylinder internal combustion engine that can be switched between all-cylinder operation for injecting fuel in cylinders belonging to a group,
A turbocharger provided for each cylinder group and driven by exhaust from each cylinder group;
An exhaust passage provided for each cylinder group and provided with a turbine of the supercharger;
A communication passage communicating the exhaust passages on the upstream side of the turbine;
A flow amount of exhaust gas that is provided in the communication passage and flows into the exhaust passage of the cylinder group in which fuel injection is stopped in the partial cylinder operation from the cylinder group in which fuel injection is performed in the partial cylinder operation through the communication passage A flow rate control means which is a valve for controlling
With
When the internal combustion engine is accelerated during the partial cylinder operation to switch from the partial cylinder operation to the full cylinder operation, the flow rate is changed before the partial cylinder operation is switched to the full cylinder operation. The flow rate of the exhaust gas in the communication path is increased by the control means.

  That is, in the variable cylinder internal combustion engine according to the present invention, an exhaust passage and a supercharger are provided for each cylinder group, and the upstream side of the turbine of the supercharger in the exhaust passage of each cylinder group is communicated by a communication passage. ing. The communication path is provided with a flow rate control means so that the amount of exhaust gas flowing through the communication path can be controlled. In the present invention, when the variable cylinder internal combustion engine is accelerated from the state where the partial cylinder operation is performed and shifts to the full cylinder operation, the communication path is changed before the shift from the partial cylinder operation to the full cylinder operation. The flow rate of exhaust gas flowing through is increased.

  By doing so, the exhaust of the cylinder group that is operating in the partial cylinder operation is caused to flow into the exhaust passage of the cylinder group that is deactivated in the partial cylinder operation, and the turbocharger of the deactivated cylinder group is driven in advance. Let me.

  In this way, when the operation of the cylinder belonging to the deactivated cylinder group is resumed by shifting from the partial cylinder operation to the full cylinder operation, the rotation of the turbocharger provided for the cylinder group is resumed. The number can be increased in advance, and the engine output of the entire internal combustion engine can be increased more smoothly. As a result, better acceleration performance can be obtained.

  Here, as the flow rate control means for controlling the flow rate of the exhaust gas in the communication path, a control valve or shutter provided in the communication path, which can close or open the communication path or change the opening degree. Etc. can be illustrated.

Further, in the present invention, an intake passage provided for each cylinder group and provided with a compressor of the supercharger of the cylinder group;
One end of the intake passage of the cylinder group in which fuel injection stops during the partial cylinder operation is connected to the downstream side of the compressor, and an intake outflow passage that causes the intake air flowing through the intake passage to flow out of the intake passage;
Second flow rate control means that is provided in the intake outflow passage and is a valve that controls the flow amount of the intake air flowing out from the intake passage of the cylinder group in which fuel injection is stopped in the partial cylinder operation through the intake outflow passage. When,
Further comprising
During the period when the flow rate control means is open and the flow rate of the exhaust gas in the communication passage is increased, the flow rate of the intake air in the intake flow path is opened by the second flow rate control means. May be increased.

  As described above, in the present invention, when shifting from the partial cylinder operation to the full cylinder operation, the exhaust amount in the cylinder group operating in the partial cylinder operation is increased by increasing the flow amount of the exhaust gas flowing through the communication path. However, the rotational speed of the supercharger provided for the cylinder group that has been stopped is increased. In this case, when the rotation speed of the supercharger starts to increase, the cylinders belonging to the cylinder group that has been stopped are not operating, so the intake air supercharged by the increase in the rotation speed of the supercharger is In some cases, the cylinder is not introduced into a cylinder belonging to the cylinder group that has been inhaling. In this case, since the intake air supercharged by the supercharger loses its place to go, the back pressure in the intake passage increases, which may hinder the increase in the rotational speed of the supercharger.

  Therefore, in the present invention, when an intake air outflow passage is provided on the downstream side of the compressor of the supercharger of the intake passage in the cylinder group that has been stopped in the partial cylinder operation, when the rotational speed of the supercharger increases. The second circulation amount control means increases the amount of intake air flowing through the intake outlet passage, thereby allowing the intake air supercharged by the supercharger to escape from the intake passage.

  If it does so, the raise of the back pressure in an intake passage can be suppressed, and it can suppress that the raise of the rotation speed of the said supercharger is inhibited. As a result, the rotational speed of the supercharger provided for the cylinder group that has been stopped in the partial cylinder operation can be more reliably increased. Examples of the second flow rate control means include a control valve and a shutter that are provided in the intake outflow passage and can close or open the intake outflow passage or change the opening degree.

  Here, the intake outflow passage may be connected to an intake passage of a cylinder group operating in the partial cylinder operation. By doing so, the second flow rate control means causes the second flow rate control means to pass through the intake outflow passage when the rotation speed of the supercharger provided for the cylinder group that has been stopped in the partial cylinder operation increases. By increasing the amount of intake air flowing, it is introduced into the intake passage of the operating cylinder group and discharged through the cylinders belonging to the operating cylinder group. As a result, it is possible to suppress an increase in the back pressure in the intake passage of the cylinder group that has been stopped in the partial cylinder operation, and the rotational speed of the supercharger provided for the cylinder group that has been stopped in the partial cylinder operation. It is possible to satisfactorily suppress the inhibition of the increase of

  Further, the intake outflow passage may be opened to the atmosphere at an end portion that is not connected to the intake passage. By doing so, the second flow rate control means causes the second flow rate control means to pass through the intake outflow passage when the rotation speed of the supercharger provided for the cylinder group that has been stopped in the partial cylinder operation increases. By increasing the amount of intake air that circulates, it is released into the atmosphere. Also by this, it is possible to satisfactorily inhibit the increase in the rotational speed of the supercharger provided for the cylinder group that has been stopped in the partial cylinder operation.

  The means for solving the problems in the present invention can be used in combination as much as possible.

  In the present invention, when the variable cylinder internal combustion engine is accelerated in a state where the partial cylinder operation is performed, the engine output is smoothly increased in the process of shifting from the partial cylinder operation to the full cylinder operation. be able to.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a variable cylinder internal combustion engine according to the present embodiment. A variable cylinder internal combustion engine 1 shown in FIG. 1 (hereinafter simply referred to as “internal combustion engine 1”) is a so-called V-type 8-cylinder internal combustion engine, and includes two banks 10 and 20. The bank 10 is provided with four cylinders 2a to 2d, and the bank 20 is provided with four cylinders 12a to 12d.

The two banks 10 and 20 of the internal combustion engine 1 are connected to intake branch pipes 3 and 13 provided for each bank, and the branch pipes of the intake branch pipes 3 and 13 are connected to the cylinders 2a to 2d and 12a. ˜12d combustion chamber is connected via an intake port (not shown). The intake branch pipes 3 and 13 are connected to the intake pipes 4 and 14 on the upstream side, and the intake pipes 4 and 14 include compressors 11a of centrifugal superchargers (turbochargers) 11 and 21 provided for each bank. And 21a are attached. Further, an intake throttle valve that adjusts the amount of intake air that flows through the intake pipes 4 and 14 and is introduced into the banks 10 and 20 at a portion of the intake pipes 4 and 14 that is located immediately upstream of the intake branch pipes 3 and 13. 7 and 17 are provided.

  On the other hand, the banks 10 and 20 are connected to exhaust branch pipes 5 and 15 provided for each bank, and the branch pipes of the exhaust branch pipes 5 and 15 are shown as combustion chambers of the cylinders 2a to 2d and 12a to 12d. Not connected through the exhaust port. The exhaust branch pipes 5 and 15 are connected to the exhaust pipes 6 and 16 on the downstream side, and the exhaust pipes 6 and 16 are connected to the turbines 11b and 21b of the centrifugal superchargers 11 and 21 provided for each bank. Is attached. Further, the exhaust pipes 6 and 16 are connected to a muffler (not shown) downstream.

  Further, the upstream portion of the turbine 11 b in the exhaust pipe 6 and the upstream portion of the turbine 21 b in the exhaust pipe 16 are communicated with each other by a communication pipe 30. The communication pipe 30 is provided with a control valve 32 that controls the amount of exhaust gas flowing through the communication pipe 30. On the other hand, the downstream portion of the compressor 11 a in the intake pipe 4 and the downstream portion of the compressor 21 a in the intake pipe 14 are communicated by the second communication pipe 31. The second communication pipe 31 is provided with a second control valve 33 that controls the amount of intake air flowing through the second communication pipe 31. Here, the control valve 32 corresponds to the flow rate control means in the present embodiment, and the second control valve 33 corresponds to the second flow rate control means. The communication pipe 30 corresponds to the communication path in this embodiment. Further, the second communication pipe 31 corresponds to an intake / outflow passage in the present embodiment.

  The internal combustion engine 1 configured as described above is provided with an electronic control unit (ECU) 40 for controlling the internal combustion engine 1. The ECU 40 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver. In addition to fuel injection valves and spark plugs (not shown) in the cylinders 2a to 2d and 12a to 12d belonging to the banks 10 and 20, the ECU 40 is connected to intake throttle valves 7 and 17 via electric wiring. In addition, the amount of intake air introduced into the banks 10 and 20 is controlled in addition to fuel supply and ignition in each of the cylinders 2a to 2d and 12a to 12d according to a command from the ECU 40. Further, a control valve 32 and a second control valve 33 are connected to the ECU 40, and the amount of exhaust gas flowing through the communication pipe 30 and the amount of intake air flowing through the second communication pipe 31 are controlled by commands of the ECU 40. The

  The ECU 40 includes a CPU, a ROM, a RAM, and the like. The ROM stores a program for performing various controls of the internal combustion engine 1 and a map storing data. Examples of programs stored in the ROM of the ECU 40 include a routine for switching between partial cylinder operation and all cylinder operation according to the operating state of the internal combustion engine 1 (description is omitted), and in this embodiment described later. A control valve opening change routine can be exemplified.

  The internal combustion engine 1 in this embodiment belongs to the cylinders 2a to 2d belonging to the bank 10 and the bank 20 when the ECU 40 detects that the partial cylinder operation condition is satisfied, for example, the operation state belongs to a predetermined low load operation state. Of the cylinders 12a to 12d, for example, the cylinders 2a to 2d belonging to the bank 10 are deactivated and the partial cylinder operation is performed. Specifically, the fuel injection from the fuel injection valves and the operation of the intake and exhaust valves in the cylinders 2a to 2d belonging to the bank 10 to be stopped are stopped. On the other hand, when the partial cylinder operation condition is no longer satisfied, such as when the operation state deviates from the low load operation state described above, the fuel injection from the fuel injection valves and the operation of the intake and exhaust valves in the cylinders 2a to 2d are resumed. The partial cylinder operation is canceled and the full cylinder operation is started.

Here, the predetermined low load operating state is an operating state region in which it is determined that the required load can be sufficiently satisfied only by operating the cylinder belonging to one bank, and is set experimentally in advance. Is. Further, in the future, in the partial cylinder operation, the description will be made on the assumption that the cylinders 2a to 2d belonging to the bank 10 are deactivated, but it is needless to say that the cylinders 12a to 12d belonging to the bank 20 may be deactivated.

  Next, a case will be described in which the internal combustion engine 1 is accelerated in a state where partial cylinder operation is performed by deactivating the cylinders 2a to 2d belonging to the bank 10 and shifts from partial cylinder operation to full cylinder operation. In this case, first, when an accelerator (not shown) is depressed, the amount of exhaust discharged from the cylinders 12a to 12d belonging to the bank 20 and the exhaust pressure increase. Then, the rotational speed of the centrifugal supercharger 21 increases, and the intake air to the cylinders 12a to 12d belonging to the bank 20 is supercharged. Thereafter, the operation of the fuel injection and intake / exhaust valves in the cylinders 2a to 2d belonging to the bank 10 is restarted by shifting from the partial cylinder operation to the full cylinder operation. As a result, the rotational speed of the centrifugal supercharger 11 starts to increase, and supercharging of the intake air introduced into the cylinders 2a to 2d belonging to the bank 10 is started.

  In this case, when the bank 10 resumes operation, the intake air introduced into the cylinders 2a to 2d belonging to the bank 10 is sufficiently large because the rotational speed of the centrifugal supercharger 11 is low when the partial cylinder operation is released. In some cases, the engine output of the internal combustion engine 1 as a whole may have a step difference. As a result, the engine output cannot be increased smoothly, and it may be difficult to obtain sufficient acceleration performance.

  Therefore, in the present embodiment, when the internal combustion engine 1 is requested to accelerate, when the partial cylinder operation is shifted to the full cylinder operation, the operation of the bank 10 that has been stopped in the partial cylinder operation is resumed. Before, the rotational speed of the centrifugal supercharger 11 was increased so that the intake air to the cylinders 2a to 2d belonging to the bank 10 could be sufficiently supercharged when the operation of the bank 10 was resumed.

  Specifically, the control valve 32 and the second control valve 33 are closed during the partial cylinder operation, and the acceleration requested by depressing the accelerator during the partial cylinder operation has a predetermined acceleration. When the acceleration is equal to or higher than the reference acceleration, the control valve 32 and the control valve 33 are opened.

  That is, when the internal combustion engine 1 is requested to accelerate beyond the reference acceleration, it is predicted that the operation state of the internal combustion engine 1 will deviate from a predetermined low load state and shift from partial cylinder operation to full cylinder operation. By opening the valve 32, a part of the exhaust from the cylinders 12a to 12d belonging to the bank 20 is introduced into the exhaust pipe 6 to drive the turbine 11b. Accordingly, before the operation of the cylinders 2a to 2d belonging to the bank 10 is resumed, the rotational speed of the centrifugal supercharger 10 can be increased, and the operation of the cylinders 2a to 2d belonging to the bank 10 is resumed. From the beginning, the intake air introduced into the cylinders 2a to 2d belonging to the bank 10 can be sufficiently supercharged. As a result, the engine output of the internal combustion engine 1 as a whole can be increased smoothly, and good acceleration performance can be obtained.

  At that time, the second control valve 33 is opened to introduce the intake air supercharged by the supercharger 11 into the intake pipe 14 via the second communication pipe 31. By doing so, before the operation of the cylinders 2a to 2d belonging to the bank 10 is resumed, the back pressure in the intake pipe 4 rises without the intake air supercharged by the compressor 11a being introduced into the cylinders 2a to 2d. It is possible to suppress the increase in the rotational speed of the centrifugal supercharger 11.

  FIG. 2 shows a control valve opening changing routine in the present embodiment. This routine is a program stored in the ROM in the ECU 40 and is executed every predetermined period while the internal combustion engine 1 is in operation.

  When this routine is executed, first, in S101, it is determined whether or not the internal combustion engine 1 is in partial cylinder operation. Specifically, the determination may be made by detecting the operation signals of the fuel injection valves in the cylinders 2a to 2d belonging to the bank 10, or the engine load of the internal combustion engine 1 based on the outputs of an accelerator position sensor and a crank position sensor (not shown). Alternatively, the engine speed may be detected and the determination may be made based on whether or not the operating state of the internal combustion engine 1 belongs to a predetermined low-load operating state.

  Here, when it is determined that the internal combustion engine 1 is not in partial cylinder operation, it is determined that the internal combustion engine 1 is in full cylinder operation and it is not necessary to open the control valve 32 and the second control valve 33. Therefore, the process proceeds to S106. In this case, in S106, the control valve 32 and the second control valve 33 are closed or the closed state is continued, and then this routine is ended. That is, during all cylinder operation, the control valve 32 and the second control valve 33 are closed. On the other hand, if it is determined in S101 that the internal combustion engine 1 is in partial cylinder operation, the process proceeds to S102.

  In S102, the accelerator depression amount in the internal combustion engine 1 is detected from the output of the accelerator position sensor. In S101, when the output signal of the accelerator position sensor is used to determine whether or not the partial cylinder is operating, the value detected at that time may be detected by reading it from the RAM. When the process of S102 ends, the process proceeds to S103.

  In S103, it is determined from the accelerator depression amount detected in S102 whether or not the acceleration required for the internal combustion engine 1 is greater than or equal to a reference acceleration. Here, the reference acceleration is an acceleration as a threshold value that is determined to shift from the partial cylinder operation to the full cylinder operation in the near future when the internal combustion engine 1 is requested to accelerate further during the partial cylinder operation. It is obtained experimentally in advance.

  If it is determined in S103 that the acceleration required for the internal combustion engine 1 is greater than or equal to the reference acceleration, the operation shifts from the partial cylinder operation to the full cylinder operation in the near future, and the cylinders 2a to 2d belonging to the bank 10 are operated. Therefore, the process proceeds to S104. On the other hand, if it is determined that the acceleration required for the internal combustion engine 1 is smaller than the reference acceleration, it is determined that the operation of the cylinders 2a to 2d belonging to the bank 10 will not be resumed for the time being, and the process proceeds to S105.

  In S104, the control valve 32 and the second control valve 33 are opened. Then, a part of the exhaust of the bank 20 that is already accelerated due to the accelerator being depressed can be introduced into the exhaust pipe 6, and the turbine 11b of the centrifugal supercharger 11 can be driven by the exhaust. At the same time, the intake air to be introduced into the cylinders 2 a to 2 d belonging to the bank 10 supercharged by the compressor 11 a can be introduced into the cylinders 12 a to 12 d belonging to the bank 20.

  As a result, the rotational speed of the supercharger 11 can be sufficiently increased before the operation of the cylinders 2a to 2d belonging to the bank 10 is resumed, and the engine output of the internal combustion engine 1 as a whole can be increased smoothly. it can.

  In S105, the control valve 32 and the second control valve 33 are closed or the closed state is continued. In this case, the acceleration request is met by an increase in the rotational speed of the supercharger 21 and an increase in the output of the cylinders 12a to 12d belonging to the bank 20. When the process of S104 or S105 ends, this routine ends.

As described above, in the present embodiment, when the acceleration required for the internal combustion engine 1 during the partial cylinder operation is smaller than the reference acceleration, the partial cylinder operation is continued,
The control valve 32 and the second control valve 33 are closed. In this case, the acceleration request is met by an increase in the rotational speed of the supercharger 21 and an increase in output in the cylinders 12a to 12d belonging to the bank 20. On the other hand, when the acceleration required for the internal combustion engine 1 during the partial cylinder operation is equal to or higher than the reference acceleration, the control valve 32 and the second control valve 33 are opened. In this case, first, the rotational speed of the supercharger 11 increases, and then the operation of the cylinders 2a to 2d belonging to the bank 10 is resumed.

  By so doing, when the internal combustion engine 1 is requested to accelerate, the engine output of the internal combustion engine 1 as a whole can be increased smoothly even when shifting from partial cylinder operation to full cylinder operation, and good acceleration is achieved. Performance can be obtained.

  In the control valve opening change routine in the present embodiment, whether to open the control valve 32 and the second control valve 33 is determined depending on whether the required acceleration is equal to or higher than the standardized speed. And the criterion for determining whether to open the second control valve 33 is not limited to this. For example, when the operating state of the internal combustion engine 1 becomes a boundary region between a predetermined low-load operating state and other operating states, it is expected that a transition from partial cylinder operation to full cylinder operation will occur in the near future. Judgment criteria may be used.

  Here, in this embodiment, when the control valve 32 and the second control valve 33 are opened, the respective control valves may be fully opened or not. For example, the final opening of the control valve 32 and the second control valve 33 may be changed according to the required acceleration. Further, the valve opening speed until the final opening is reached may be changed according to the time from the start of acceleration until the operation of the cylinders 2a to 2d belonging to the bank 10 is resumed. By doing so, the engine output as the whole internal combustion engine 1 can be raised more smoothly.

  Next, in this embodiment, when the rotational speed of the centrifugal supercharger 11 is increased before the shift from the partial cylinder operation to the full cylinder operation, the intake air supercharged by the compressor 11a is supplied to the second communication pipe. A mode in which the air is released into the atmosphere instead of being introduced into the cylinders 12a to 12d belonging to the bank 20 through the intake pipe 14 and the intake pipe 14 will be described. A schematic diagram of the internal combustion engine 1 according to this embodiment is shown in FIG. In FIG. 3, the intake pipes 4 and 14 are not connected by the second communication pipe 31. Instead, a discharge pipe 34 for discharging the intake air supercharged by the rotation of the compressor 11 a to the atmosphere is connected to the downstream portion of the compressor 11 a of the intake pipe 4. Further, the discharge pipe 34 is provided with a third control valve 35 that controls the flow rate of the intake air in the discharge pipe 34.

  In this aspect, when it is determined that the acceleration required for the internal combustion engine 1 is greater than or equal to the reference acceleration during partial cylinder operation, the control valve 32 and the third control valve 35 are opened. By doing so, a part of the exhaust from the cylinders 12a to 12d belonging to the bank 20 is introduced into the exhaust pipe 6 to drive the turbine 11b and to release the intake air supercharged by the compressor 11a to the atmosphere. .

  This also can suppress an increase in back pressure in the intake passage 4 on the downstream side of the compressor 11a. As a result, in the transition from the partial cylinder operation to the all cylinder operation, the rotational speed of the centrifugal supercharger 11 can be sufficiently increased before the operation of the cylinders 2a to 2d belonging to the bank 10 is resumed. 1 The engine output as a whole can be raised smoothly. In this embodiment, the discharge pipe 34 corresponds to the intake / outflow passage, and the third control valve 35 corresponds to the second flow rate control means.

Further, in this embodiment, as a substitute for the communication pipe 30 and the control valve 32 or in addition to the communication pipe 30 and the control valve 32, a wastegate valve for limiting the exhaust pressure in the turbine 21b of the centrifugal supercharger 21 and Further, a mode may be adopted in which a third communication pipe (not shown) for returning the exhaust gas escaped from the exhaust pipe 16 by the wastegate valve to the exhaust pipe 6 is provided. In this way, when the exhaust pressure in the turbine 21b of the centrifugal supercharger 21 becomes equal to or higher than a predetermined pressure during the partial cylinder operation, the wastegate valve is opened to circulate through the exhaust pipe 16. Part of the exhaust can be introduced into the exhaust pipe 6 via the third communication pipe. Here, the predetermined pressure is an exhaust pressure as a threshold value that causes a risk of damaging the turbine 21b of the centrifugal supercharger 21 when the exhaust pressure becomes higher than this, and is determined experimentally in advance.

  If it does so, the turbine 11b of the centrifugal supercharger 11 can be driven by the exhaust which should be discharge | released outside originally by opening a wastegate valve, and effective utilization of energy can be aimed at. Further, in the partial cylinder operation, when rapid acceleration is required such that the exhaust pressure increases as the waste gate valve opens, the rotational speed of the centrifugal supercharger 11 in the bank 10 that is at rest is automatically set. Can be raised.

It is a figure which shows schematic structure of the variable cylinder internal combustion engine in the Example of this invention. It is a flowchart which shows the control valve opening degree change routine in the Example of this invention. It is a figure which shows another aspect of the variable cylinder internal combustion engine in the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Variable cylinder internal combustion engine 2a, 2b, 2c, 2d ... Cylinder 3, 13 ... Intake branch pipe 4, 14 ... Intake pipe 5, 15 ... Exhaust branch pipe 6, 16, ... Exhaust pipes 7, 17 ... intake throttle valves 10, 20 ... banks 11, 21 ... centrifugal turbochargers 11a, 21a ... compressors 11b, 21b ... turbines 12a, 12b, 12c, 12d ... Cylinder 30 ... Communication pipe 31 ... Second communication pipe 32 ... Control valve 33 ... Second control valve 34 ... Drain pipe 35 ... Third control valve 40 ... ECU

Claims (4)

Partial cylinder operation in which a plurality of cylinders in an internal combustion engine are divided into two or more cylinder groups, and fuel injection of cylinders belonging to some cylinder groups is stopped according to the operating state of the internal combustion engine, and cylinders belonging to all cylinder groups A variable-cylinder internal combustion engine that can be switched to all-cylinder operation that performs fuel injection of
A turbocharger provided for each cylinder group and driven by exhaust from each cylinder group;
An exhaust passage provided for each cylinder group and provided with a turbine of the supercharger;
A communication passage communicating the exhaust passages on the upstream side of the turbine;
A flow amount of exhaust gas that is provided in the communication passage and flows into the exhaust passage of the cylinder group in which fuel injection is stopped in the partial cylinder operation from the cylinder group in which fuel injection is performed in the partial cylinder operation through the communication passage A flow rate control means which is a valve for controlling
With
When the internal combustion engine is accelerated during the partial cylinder operation to switch from the partial cylinder operation to the full cylinder operation, the flow rate is changed before the partial cylinder operation is switched to the full cylinder operation. A variable cylinder internal combustion engine characterized in that a flow rate of the exhaust gas in the communication path is increased by a control means. An intake passage provided for each cylinder group and provided with a compressor of the turbocharger of the cylinder group;
One end of the intake passage of the cylinder group in which fuel injection stops during the partial cylinder operation is connected to the downstream side of the compressor, and an intake outflow passage that causes the intake air flowing through the intake passage to flow out of the intake passage;
Second flow rate control means that is provided in the intake outflow passage and is a valve that controls the flow amount of the intake air flowing out from the intake passage of the cylinder group in which fuel injection is stopped in the partial cylinder operation through the intake outflow passage. When,
Further comprising
During the period when the flow rate control means is open and the flow rate of the exhaust gas in the communication passage is increased, the flow rate of the intake air in the intake flow path is opened by the second flow rate control means. The variable cylinder internal combustion engine according to claim 1, characterized in that is increased. The variable cylinder internal combustion engine according to claim 2, wherein the other end of the intake outflow passage is connected to an intake passage of a cylinder group in which fuel injection is performed during the partial cylinder operation.   The variable cylinder internal combustion engine according to claim 2, wherein the other end of the intake / outflow passage is opened to the atmosphere.

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