JP2009185658A - Exhaust emission control device for multi-cylinder internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce exhaust emission of an engine in which cylinder deactivation is executed by inhibiting temperature of a catalytic converter from dropping and atmosphere of a catalyst from getting lean even if part of cylinders of a multi-cylinder internal combustion engine are deactivated. <P>SOLUTION: A V-type engine 1 deactivating a second bank 1b according to operation conditions is provided with an exhaust gas supply passage 31 for supplying combustion exhaust gas of a first bank 1a in which operation is continued to an intake system of the second bank 1b, and a control valve 32 opening and closing the exhaust gas supply passage 31. When the second bank 1b is deactivated, the control valve 32 is opened to introduce exhaust gas of the first bank 1a to each cylinder of the second bank 1b. Consequently, fresh air rate in each cylinder of the second bank 1b is reduced, temperature of gas flowing into the catalytic converter 13 from the second bank 1b is increased, and oxygen concentration is reduced. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust treatment device for a multi-cylinder internal combustion engine in which some cylinders are deactivated depending on operating conditions.

In Patent Document 1, when the engine operation required for driving the vehicle-mounted device is requested when the automobile is not capable of self-running or when the engine is stopped, the operating cylinder is obtained so that the necessary engine operation can be obtained. A control device for a multi-cylinder internal combustion engine that limits the number is disclosed.
JP 2002-206437 A

By the way, although the fuel injection is stopped for the cylinders which are deactivated due to the limitation on the number of operating cylinders as described above, the pistons of the deactivated cylinders are reciprocated to suck and discharge air. However, it is introduced into a catalytic converter for purifying exhaust gas that is interposed in the exhaust passage as it is or mixed with the combustion exhaust gas of the cylinder in which other operation is continued.
Here, when the cylinder deactivation period is long or when the outside air temperature is low, the catalyst temperature of the catalytic converter is lowered by the air passing through the deactivation cylinder, and furthermore, the catalyst is in a lean atmosphere, so that the conversion rate in the catalyst is reduced. There is a problem that the exhaust emission decreases and the exhaust emission increases.

  The present invention has been made in view of the above problems, and even when some cylinders of a multi-cylinder internal combustion engine are stopped, the temperature reduction of the catalytic converter and the leaning of the catalyst atmosphere can be suppressed, and the cylinder is stopped. The purpose is to reduce exhaust emissions in engines.

  Therefore, in the present invention, when some cylinders of a multi-cylinder internal combustion engine are deactivated, an exhaust supply passage for supplying combustion exhaust of other cylinders that are continuously operated to the intake system of the deactivated cylinders A control valve interposed in the exhaust supply passage and controlling the supply of combustion exhaust to the intake system of the deactivated cylinder, and when the partial cylinder is deactivated, the control valve is controlled to open and the Combustion exhaust is supplied to the intake system of the idle cylinder.

  According to the above invention, when some cylinders are deactivated, the combustion exhaust gas of the other cylinders that are continuously operated is supplied to the intake system of the deactivated cylinders. The amount of fresh air passing through the cylinder can be reduced, the temperature of the gas discharged from the idle cylinder can be increased, and the temperature reduction and lean atmosphere can be suppressed in the catalytic converter into which the gas discharged from the idle cylinder is introduced. Can be avoided.

Embodiments of the present invention will be described below.
FIG. 1 is a diagram showing an internal combustion engine for a vehicle in the first embodiment.
The internal combustion engine 1 shown in FIG. 1 is a V-type multi-cylinder engine composed of two banks (cylinder groups), a first bank (left bank) 1a and a second bank (right bank) 1b. Note that the number of cylinders of the internal combustion engine 1 may be a multi-cylinder having two or more cylinders.

Pistons 2 a and 2 b are provided in the cylinders of the banks 1 a and 1 b, and the reciprocating motion of the pistons 2 a and 2 b is converted into rotation of the crankshaft 4 by the connecting rod 3.
An intake passage 6a and an exhaust passage 7a are connected to the combustion chamber 5 of each cylinder of the first bank 1a (first cylinder group). When the intake valve 8a is opened, the intake passage 6a and the combustion chamber 5 communicate with each other. When the exhaust valve 9a is opened, the exhaust passage 7a and the combustion chamber 5 communicate with each other.

Similarly, an intake passage 6b and an exhaust passage 7b are connected to the combustion chamber 5 of each cylinder of the second bank 1b (second cylinder group). When the intake valve 8b is opened, the intake passage 6b and the combustion chamber 5 are opened. When the exhaust valve 9b is opened, the exhaust passage 7b and the combustion chamber 5 communicate with each other.
In the intake passages 6a and 6b, fuel injection valves 10a and 10b are provided for each cylinder.
The fuel injection valves 10a and 10b may be in-cylinder direct injection engines that directly inject fuel into the combustion chamber 5.

Further, throttle valves 11a and 11b are provided for each bank in the intake passages 6a and 6b on the upstream side of the fuel injection valves 10a and 10b, and the cylinders of the banks 1a and 1b are provided by the throttle valves 11a and 11b. The amount of air sucked in is adjusted.
The throttle valves 11a and 11b are electronically controlled throttles that are opened and closed by a throttle motor (not shown) provided for each bank.

The intake passages 6a and 6b join the intake passage 6 common to the banks 1a and 1b on the upstream side of the throttle valves 11a and 11b, and the intake passage 6 detects the intake air flow rate of the internal combustion engine 1. An air flow sensor 12 is provided.
Further, the exhaust passages 7a and 7b merge with a common exhaust passage 7 on the downstream side, and the exhaust passage 7 is provided with a catalytic converter 13 (underfloor catalyst) for purifying exhaust. The catalytic converter 13 purifies harmful components in the exhaust.

The catalytic converter 13 is, for example, of a three-way catalyst type, and has the action of oxidizing HC and CO in exhaust gas and reducing NOx.
Here, there is provided an exhaust supply passage (EGR passage) 31 that connects the exhaust passage 7a of the first bank 1a and the intake passage 6b on the downstream side of the throttle valve 11b of the second bank 1b. The combustion exhaust of the cylinders in the first bank 1a can be supplied to the intake system of the cylinders in the second bank 1b.

The exhaust supply passage 31 is provided with a control valve (EGR valve) 32 that controls the supply of combustion exhaust gas through the exhaust supply passage 31.
In the center of the cylinder head constituting the combustion chamber 5, spark plugs 15a and 15b are provided, respectively, and ignition plugs 16a and 16b with built-in power transistors are directly attached to the spark plugs 15a and 15b, respectively. .

Electromagnetic drive devices 18a and 18b (see Japanese Patent Application Laid-Open No. 2001-164949) are provided as valve operating mechanisms for opening and closing the intake valves 8a and 8b and the exhaust valves 9a and 9b.
The electromagnetic driving devices 18a and 18b urge the intake valves 8a and 8b and the exhaust valves 9a and 9b to intermediate positions of opening and closing operations by springs, and are opened and closed by electromagnetic force generated by the valve opening side electromagnetic coil and the valve closing side electromagnetic coil. It is a device to do.

In the electromagnetic drive devices 18a and 18b, the opening timing and closing timing of the intake valves 8a and 8b and the exhaust valves 9a and 9 can be controlled by changing the energization control timing to the valve opening side electromagnetic coil and valve closing side electromagnetic coil. The operating angles of the intake valves 8a and 8b and the exhaust valves 9a and 9b or the maximum lift amount during the valve opening can be changed, and can be fixed to the valve opened state.
Further, as a valve operating mechanism for opening and closing the intake valves 8a and 8b and the exhaust valves 9a and 9b, two types of cam pieces are provided on the camshaft instead of the electromagnetic drive devices 18a and 18b, and the cam pieces used for driving the valve By switching these, a variable valve timing / lift mechanism VVL (cam switching mechanism: see Japanese Patent Laid-Open No. 5-33621) that changes the valve opening / closing timing and the lift amount can be used.

In other words, the reference numerals 18a and 18b shown in FIG. 1 can be used as the variable valve timing / lift mechanism VVL in place of the electromagnetic driving device.
When the variable valve timing / lift mechanism VVL (cam switching mechanism) disclosed in JP-A-5-33621 is used, the maximum lift amount can be held by changing the shape of the high-speed cam. Specifically, as two types of cam pieces, a first cam set to a cam profile that opens and closes intake valves 8a and 8b and exhaust valves 9a and 9b in synchronization with engine rotation, and an intake valve And a second cam set to a cam profile that holds the exhaust valves 9a and 9b at the maximum lift amount.

  Further, as a valve operating mechanism for opening and closing the intake valves 8a and 8b and the exhaust valves 9a and 9b, instead of the electromagnetic driving devices 18a and 18b, Japanese Patent Application Laid-Open Nos. 2004-270608 and 2003-49672 are disclosed. It is possible to use variable operating angle lift mechanisms VEL28a and 28b that continuously change the maximum valve lift amount of the intake valves 8a and 8b and the exhaust valves 9a and 9b together with the valve operating angle (see FIG. 7). .

The system shown in FIG. 7 shows an example in which the valve operating system in the system shown in FIG. 6 to be described later is replaced with variable operating angle lift mechanisms VEL 28a and 28b. However, in the system shown in FIG. 1 and the system shown in FIG. It is possible to replace the driving devices 18a and 18b with variable operating angle lift mechanisms VEL28a and 28b.
The variable operating angle lift mechanism VEL is provided only on the intake valves 8a and 8b side, and the exhaust valves 9a and 9b can be opened and closed at a constant operating angle, lift amount, and valve timing based on a fixed cam profile.

  An engine control module (ECM) 30 incorporating a microcomputer is inputted with signals from various sensors, and the fuel injection valves 10a and 10b, the power transistor built-in ignition coil 16a, 16b, throttle valves 11a and 11b (throttle motor), control valve 32, electromagnetic drive devices 18a and 18b (or variable valve timing and lift mechanism VVL, variable operating angle lift mechanisms VEL 28a and 28b), and the like.

  In addition to the airflow sensor 12, the various sensors include a crank angle sensor 21 that outputs a reference crank angle signal REF for each reference angle position of the crankshaft 4 and a position signal POS for each unit angle, and an accelerator operated by the driver. Accelerator opening sensor 22 for detecting pedal depression amount (accelerator opening) ACC, water temperature sensor 23 for detecting cooling water temperature TW of internal combustion engine 1, and vehicle traveling speed VSP using internal combustion engine 1 as a drive source are detected. Oxygen in the exhaust gas is provided in a vehicle speed sensor 24, intake pressure sensors 25a and 25b for detecting pressure (intake pressure) PB in the intake passages 6a and 6b downstream of the throttle valves 11a and 11b, and the exhaust passages 7a and 7b, respectively. Oxygen sensors 29a and 29b that generate output AF corresponding to the concentration are provided.

The oxygen sensors 29a and 29b may be stoichiometric sensors whose output changes suddenly with the theoretical air-fuel ratio as a boundary, or so-called wide-area sensors that can detect the air-fuel ratio in a wide area.
In the control of the fuel injection valves 10a and 10b, the fuel injection amount is calculated based on the intake air flow rate, the engine rotational speed, the coolant temperature, etc., and the stroke of each cylinder is calculated for each fuel injection valve 10a and 10b. Accordingly, an injection pulse signal having a pulse width corresponding to the fuel injection amount is output.

Further, the ignition timing by the ignition plugs 15a, 15b is calculated from the engine load, the engine rotational speed, etc., and the energization start / interruption timing in the ignition coils 16a, 16b is determined from the ignition timing and the required energization time. Based on the above, an ignition signal for turning on / off the power transistor built in the ignition coils 16a, 16b is output.
Further, a target throttle opening is calculated based on the accelerator opening detected by the accelerator opening sensor 22, and the throttle motor is adjusted so that the opening of the throttle valves 11a and 11b approaches the target throttle opening. A drive signal is output.

Further, in this embodiment, when a predetermined cylinder deactivation condition is satisfied, the operation of each cylinder in the first bank (left bank) 1a is continued, while the operation for each cylinder in the second bank (right bank) 1b is continued. The fuel injection / ignition is stopped and stopped.
As described above, by stopping the operation of some cylinders (second bank 1b) of the internal combustion engine 1, the fuel efficiency is improved, and on-vehicle equipment (such as an air conditioner compressor and an alternator) driven by the internal combustion engine 1 is improved. Can be kept operational.

As the cylinder deactivation condition, for example, when the vehicle is stopped and the internal combustion engine 1 is in an idle state, the cylinder deactivation is performed, and / or when the internal combustion engine 1 travels with little change in speed from a low load to a medium load. Perform cylinder deactivation.
However, the operating conditions for stopping the second bank 1b are not limited to the above conditions.
Hereinafter, details of the deactivation control of the partial cylinders will be described.

The flowchart of FIG. 2 shows the procedure of the partial cylinder deactivation control, and is executed every certain minute time.
First, in step S101, the operating state of the internal combustion engine 1 is detected. The driving state includes various driving states (vehicle speed, idle driving, etc.) that are determined as the suspension conditions of the second bank 1b.

In step S102, it is determined whether or not the second bank 1b is at rest.
If not, the process proceeds to step S103, and it is determined whether or not a condition for stopping the operation of each cylinder in the second bank 1b is satisfied.
Specifically, the vehicle speed is within a predetermined range and the vehicle is traveling at a low and medium speed, the accelerator change is not more than a predetermined value, and there is no request for acceleration or deceleration, or the vehicle is stopped. Whether or not the internal combustion engine 1 is in an idle state is determined as a stop execution condition.

If the stop condition is not satisfied, the process returns to step S101 again so that the cylinders of both banks 1a and 1b are continuously operated normally.
On the other hand, if it is determined that the stop condition is satisfied, the process proceeds to step S104, and control for stopping the operation of each cylinder in the second bank 1b is executed.
Specifically, the fuel injection / ignition in each cylinder of the second bank 1b is stopped, and the intake / exhaust valves 8b, 9b of each cylinder in the second bank 1b are connected to the electromagnetic drive device (or variable valve timing / lift mechanism). VVL) 18b fixes the valve open state (opening increasing means), controls the opening of the control valve 32 (control means), and fully closes the throttle valve 11b of the second bank 1b.

By stopping the fuel injection / ignition in each cylinder of the second bank 1b, each cylinder of the second bank 1b is stopped, while fuel injection / ignition for each cylinder of the first bank 1a is normally continued. To improve fuel efficiency while continuing the engine operation required for driving on-vehicle equipment (air conditioner compressors, alternators, etc.).
Further, by fully closing the throttle valve 11b on the idle bank side, the pressure (intake pressure) in the intake passage 6b on the downstream side of the throttle valve 11b is set to a negative pressure, and further, the control valve 32 is set in such a negative pressure generation state. By opening, a large pressure difference is generated between the exhaust passage 7a on the first bank 1a side that is normally operated and the intake passage 6b on the downstream side of the throttle valve 11b, and the first bank 1a side on which the operation is continued is continued. The combustion exhaust gas in the exhaust passage 7a is introduced into the intake passage 6b (intake system) of the second bank 1b where the operation is stopped.

  Even in the cylinders of the second bank 1b that are stopped, the piston 2b reciprocates due to the rotation of the crankshaft 4 to perform pumping, but the combustion exhaust of the first bank 1a is guided to the intake passage 6b, The second bank 1b sucks in the combustion exhaust of the first bank 1a together with the fresh air, and the fresh air rate (oxygen concentration) in the intake gas of the second bank 1b decreases.

Furthermore, in the second bank 1b, the temperature of the gas flowing through the second bank 1b and flowing to the exhaust side as compared with the case where only the fresh air is sucked by mixing the high temperature combustion gas with the low temperature intake fresh air. Becomes higher.
Therefore, even if the gas that has passed through the idle cylinder of the second bank 1b is mixed with the combustion exhaust on the first bank 1a side, the exhaust air-fuel ratio can be prevented from being significantly leaned, and the exhaust temperature can be greatly reduced. Can be suppressed.

As a result, it is possible to suppress the temperature drop of the catalytic converter 13 introduced by the exhaust gas from each bank being joined, and further to prevent the atmosphere of the catalytic converter 13 from becoming lean and reducing the NOx reduction performance. Deterioration of exhaust emission can be prevented.
When the process of stopping each cylinder of the second bank 1b is executed in step S104, the process proceeds to step S105, and it is determined whether or not the intake pressure detected by the intake pressure sensor 25 substantially matches the atmospheric pressure.

If the intake pressure does not substantially coincide with the atmospheric pressure, the process proceeds to step S106, where the process of increasing the opening of the throttle valve 11b by a preset unit opening is performed, and then the process returns to step S105. Returning, the process of step S106 is repeated until the intake pressure substantially matches the atmospheric pressure (intake pressure control means).
As a result, the throttle valve 11b is controlled to the minimum opening that allows the pressure on the downstream side of the throttle valve 11b to be atmospheric pressure, and the amount of fresh air can be suppressed to the minimum while the combustion exhaust from the first bank 1a is sucked, and the throttle The pumping loss in the idle cylinder of the second bank 1b can be reduced by setting the pressure on the downstream side of the valve 11b to atmospheric pressure.

If the amount of fresh air is reduced, the temperature of the gas passing through the second bank 1b and reaching the catalytic converter 13 can be increased, and the oxygen concentration can be reduced, contributing to maintaining the conversion rate of the catalytic converter 13. Become.
The idle cylinders of the second bank 1b can also be fixed by fixing the intake / exhaust valves 8b, 9b of the respective cylinders of the second bank 1b to the open state by the electromagnetic drive device (or variable valve timing / lift mechanism VVL) 18b. The pumping loss can be reduced, and the improvement of fuel efficiency performance due to the suspension can be further enhanced.

Further, if the intake / exhaust valves 8b and 9b are fixed fully open, gas is blown back from the exhaust side into the combustion chamber 5 in the pumping operation of each cylinder of the second bank 1b, and this also increases the amount of fresh air. Decrease.
When the second bank 1b is stopped, only the fuel injection / ignition is stopped, and the intake / exhaust valves 8b and 9b can be normally opened and closed in synchronization with the engine rotation.

Further, in the case where variable operating angle lift mechanisms VEL28a, 28b are provided instead of the electromagnetic drive devices (or variable valve timing / lift mechanism VVL) 18a, 18b, the valve lift amount in the idle cylinder is controlled to the maximum. The pumping loss can be reduced.
That is, the control (opening increasing means) of the intake / exhaust valves 8b and 9b for reducing the pumping loss increases the opening area of the intake / exhaust valves 8b and 9b (the integrated value of the valve lift amount for each crank angle). It suffices to perform the process for increasing the opening area only for the intake valve 8b.

  When the pumping loss is reduced by the electromagnetic drive device (or variable valve timing / lift mechanism VVL) 18a, 18b or variable operating angle lift mechanism VEL28a, 28b, the maximum lift is set or the maximum lift is set. For example, in order to reduce pumping loss, a predetermined lift amount having a relatively large lift amount may be used in addition to the maximum lift.

  Further, when it is determined that the stop condition is satisfied, the fuel injection and ignition in the second bank 1b are not stopped at the same time. 15 is burned by spark ignition, and the injection is continued as it is for the cylinder in the middle of injection. The injected fuel is burned by spark ignition by the spark plug 15, and the combustion exhaust gas from the last combustion is discharged in the exhaust stroke. The intake / exhaust valves 8b and 9b are fixed to the open state.

When the second bank 1b is shifted to the sleep state as described above, the next time, it is determined in step S102 that the second bank 1b is in a sleep state, and the process proceeds to step S107.
In step S107, it is determined whether or not a stop condition for stopping the operation of each cylinder in the second bank 1b is satisfied, that is, the vehicle speed is within a predetermined range and the vehicle is traveling at a low and medium speed, and the accelerator change is predetermined. It is determined whether or not there is no request for acceleration or deceleration, or whether the internal combustion engine 1 is in an idling state while the vehicle is stopped, and each cylinder in the second bank 1b is subsequently deactivated. In the case, the process proceeds to step S108.

In step S108, as in step S105, it is determined whether or not the intake pressure detected by the intake pressure sensor 25 substantially matches the atmospheric pressure.
If the intake pressure is a negative pressure, the process proceeds to step S109, the process of increasing the opening of the throttle valve 11b by the unit opening is performed, and then the process returns to step S108 again so that the intake pressure is increased. The process of step S109 is repeated until it substantially matches the atmospheric pressure (intake pressure control means).

That is, when the state in which the cylinders in the second bank 1b are inactive continues, the intake pressure sensor 25 detects during the inactive operation so that the pressure downstream of the throttle valve 11b does not become negative due to changes in the operating conditions. The result is monitored, and as soon as the negative pressure is reached, the opening of the throttle valve 11b is increased to return to the atmospheric pressure state.
Therefore, the pressure downstream of the throttle valve 11b can be maintained in the atmospheric pressure state during the pause, and the effect of reducing the popping loss can be stably obtained.

In step S105 or step S108, when it is determined that the detection result of the intake pressure sensor 25 is substantially atmospheric pressure, the opening degree of the throttle valve 11b is controlled to decrease by a minute value, and still does not become negative pressure. In this case, the opening degree is further controlled to decrease, and when the negative pressure is reached, the opening degree is returned to the previous value, whereby the minimum opening degree that is atmospheric pressure can be maintained.
If the above control is performed, when the required opening for the atmospheric pressure decreases, the throttle opening is decreased accordingly, so that the amount of fresh air in the second bank 1b can be kept to a minimum. it can.

On the other hand, when it is determined in step S107 that the predetermined stop condition for stopping the operation of each cylinder in the second bank 1b is not satisfied and the operation of each cylinder in the second bank 1b is to be resumed, the process proceeds to step S110. move on.
In step S110, the intake and exhaust valves 8b and 9b of each cylinder in the second bank 1b are released and fixed so that they are opened and closed in synchronization with the engine rotation, and fuel injection and ignition in each cylinder in the second bank 1b are performed. Then, the control valve 32 is controlled to be closed (control means), and the throttle valve 11b of the second bank 1b is controlled to a normal target value.

In resuming the operation of each cylinder in the second bank 1b, the fuel injection / ignition is restarted in accordance with the ignition order after starting the fuel injection to the cylinder that first becomes the intake stroke under the normal throttle opening.
In addition, when the variable operating angle lift mechanisms VEL28a and 28b are provided and the variable valve operating angle lift mechanisms VEL28a and 28b increase the maximum valve lift amount of the intake and exhaust valves 8b and 9b during the suspension period, In step S110, the maximum valve lift is returned to the normal target value during operation.

In the system of FIG. 1, the throttle valves 11a and 11b are provided for each bank. However, as shown in FIG. 7, only one throttle valve 11 common to each bank can be provided. In this case, the opening degree of the throttle valve 11 is controlled according to the required air amount on the combustion bank side.
When only one throttle valve 11 common to each bank is provided, the intake pressure of the stop bank cannot be controlled independently, but the stop is performed because of low and medium loads, so the operation continues. It is possible to introduce the combustion exhaust gas in the exhaust passage 7a on the first bank 1a side into the intake passage 6b (intake system) of the second bank 1b in which the operation is stopped.

In the embodiment described later, only one throttle valve 11 common to the banks can be provided.
Incidentally, as shown in FIG. 3, a combination of exhaust supply passages 31a and 31b and control valves 32a and 32b for supplying combustion exhaust gas from one bank to the intake system of the other bank may be provided for each bank. it can.

In the system shown in FIG. 3, the control as shown in the flowchart of FIG. 2 is performed for each bank, the presence / absence of a stop request of the bank is determined, and the combustion exhaust of the other bank is determined when the bank is stopped. As a result, the reduction of the conversion rate in the catalytic converter 13 can be suppressed regardless of which bank is suspended.
The routine shown in the flowcharts of FIGS. 4 and 5 specifically shows the flow of control applied to the system of FIG. 3. Steps S202 to S206 and Steps S212 to S215 are performed in the second bank 1b. The control in the case of being paused is shown.

Here, each process of step S202 to step S206 corresponds to the part of step S102 and step S107 to step S110 in the flowchart of FIG. 2, and each process of step S212 to step S215 is the step in the flowchart of FIG. This corresponds to S103 to S106.
Then, if it is determined in step S212 that a suspension start request for the second bank 1b has been generated, the processing of steps S213 to 215 is executed, and if it is determined in step S202 that the second bank 1b is being suspended, step S203 is performed. Step S206 is executed.

On the other hand, Steps S207 to S211 and Steps S216 to S219 show control when the first bank 1a is suspended.
Here, each process of step 207 to step S211 corresponds to the part of step S102 and step S107 to step S110 in the flowchart of FIG. 2, and each process of step S216 to step S219 is the step in the flowchart of FIG. This corresponds to S103 to S106.

If it is determined in step S216 that the first bank 1a pause start request has been generated, the processing of steps S217 to 219 is executed. If it is determined in step S207 that the first bank 1a is paused, step S208 is executed. Step S211 is executed.
Switching the stop bank involves selecting a bank to be stopped every time a request for stopping some cylinders is generated, and fixing the stop bank until the stop request is interrupted, or a period during which a request for stopping some cylinders is generated. Includes a case where the banks to be alternately paused are switched.

In addition, for example, the pause bank can be switched while the request for pause of some cylinders is continued, for example, the pause bank can be switched at regular intervals, or the pause bank can be switched based on a temperature drop in the pause bank. .
Furthermore, the combustion exhaust of the bank in which the operation is continued can be supplied to the intake system of the bank to be stopped, and the exhaust of the bank to be stopped can be returned to the intake system of the bank to be stopped.

  FIG. 6 shows an embodiment provided with means for returning the exhaust of the second bank 1b to the intake system of the second bank 1b during the suspension when the suspension bank is the second bank 1b. A blowback passage 35 for returning the exhaust of the second bank 1b to the intake passage 6b of the second bank 1b, together with an exhaust supply passage 31 and a control valve 32 for taking into the intake system of the second bank 1b. A blowback control valve 36 interposed in the passage 35 is provided.

When the second bank 1b is suspended, the control valve 32 is opened and the blowback control valve 36 is opened in step S104 of FIG.
According to the above configuration, the exhaust of the second bank 1b is returned to the downstream side of the throttle valve 11b. Therefore, when the intake pressure of the second bank 1b is set to atmospheric pressure, the throttle valve 11b can be closed more. .

Accordingly, the amount of fresh air in the second bank 1b during the suspension can be further reduced, the temperature of the gas passing through the second bank 1b and reaching the catalytic converter 13 is further increased, and the oxygen concentration is further decreased. be able to.
The control of the blowback control valve 36 can be applied to a system including the variable operating angle lift mechanisms VEL 28a and 28b shown in FIG. 7 and exhibits the same effect.

  In addition, when the variable operating angle lift mechanism VEL28a, 28b is provided and the maximum valve lift amount of the intake / exhaust valves 8b, 9b is increased during the pause to reduce the pumping loss, the intake / exhaust valves 8b, 9b also during the pause. Is opened and closed in synchronism with engine rotation, the exhaust valve 9b is closed in the intake stroke, so that there is no blowback from the exhaust side, and the amount of fresh air tends to increase by inhaling only from the intake side. However, by connecting the intake / exhaust system of the second bank 1b as described above, as a result, blowback from the exhaust side is generated, and an increase in the amount of fresh air can be suppressed.

The internal combustion engine 1 is not limited to a V-type engine, and the present invention can be similarly applied to an in-line engine and a horizontally opposed engine having a plurality of cylinder groups having mutually independent exhaust systems.
In addition to the catalytic converter 13 common to all the cylinders, the present invention can also be applied to the case where a catalytic converter (so-called manifold catalyst) is provided in each of the exhaust passages 7a and 7b of each bank.

  Further, the combustion exhaust supply path by the exhaust passage 31 and the control valve 32 can be used as an exhaust gas recirculation device for lowering the combustion temperature, and in this case, the conversion rate of the catalytic converter 13 during the pause is maintained. Therefore, an increase in system cost can be avoided.

1 is a system diagram of a vehicle internal combustion engine in a first embodiment. The flowchart which shows the procedure of cylinder deactivation and exhaust supply control in 1st Embodiment. The system figure of the internal combustion engine for vehicles in 2nd Embodiment. The flowchart which shows the procedure of cylinder deactivation and exhaust supply control in 2nd Embodiment. The flowchart which shows the procedure of cylinder deactivation and exhaust supply control in 2nd Embodiment. The system figure of the internal combustion engine for vehicles in 3rd Embodiment. The system diagram of the internal combustion engine for vehicles provided with the variable working angle lift mechanism VEL.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 5 ... Combustion chamber, 6a, 6b ... Intake passage, 7a, 7b ... Exhaust passage, 8a, 8b ... Intake valve, 9a, 9b ... Exhaust valve, 10a, 10b ... Fuel injection valve, 11a, 11b ... Throttle valve, 13 ... catalytic converter, 18a, 18b ... electromagnetic drive, 24 ... vehicle speed sensor, 25a, 25b ... intake pressure sensor, 30 ... engine control module, 31 ... exhaust supply passage, 32 ... control valve, 35 ... blowback Passage, 36 ... Blowback control valve

Claims (5)

In a multi-cylinder internal combustion engine in which some cylinders are deactivated according to operating conditions and a catalytic converter for purifying exhaust from each cylinder is provided in an exhaust passage.
An exhaust supply passage for supplying combustion exhaust of other cylinders that continue to operate to the intake system of the cylinders to be deactivated when the some cylinders are deactivated;
A control valve that is interposed in the exhaust supply passage and controls the supply of combustion exhaust to the intake system of the idle cylinder;
Control means for opening the control valve to supply combustion exhaust to the intake system of the deactivated cylinder when the partial cylinder is deactivated;
An exhaust treatment device for a multi-cylinder internal combustion engine characterized by comprising:   2. An exhaust treatment device for a multi-cylinder internal combustion engine according to claim 1, further comprising an intake pressure control means for controlling the pressure in the intake passage of the deactivated cylinder to an atmospheric pressure when the partial cylinder is deactivated. . A throttle valve for controlling the amount of intake air for the cylinder in which the pause is performed;
When the deactivation of the partial cylinder is started, the control means controls the opening of the control valve, while the intake pressure control means once controls the throttle valve to fully close and then the throttle valve downstream 3. An exhaust treatment apparatus for a multi-cylinder internal combustion engine according to claim 2, wherein the throttle valve is controlled to be opened so that the pressure in the intake passage on the side of the exhaust pipe becomes atmospheric pressure.   4. An exhaust treatment apparatus for a multi-cylinder internal combustion engine according to claim 3, further comprising an opening increasing means for increasing an opening area of an intake / exhaust valve of the deactivated cylinder when the partial cylinder is deactivated.   A blowback passage for supplying the exhaust of the idle cylinder to the intake system of the idle cylinder and a blowback control valve interposed in the blowback passage are provided, and the control means includes the partial cylinder The exhaust processing device for a multi-cylinder internal combustion engine according to any one of claims 1 to 4, wherein when the engine is stopped, the control valve is controlled to open and the blowback control valve is controlled to open. .

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